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1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2012 Alexander Block.  All rights reserved.
4  */
5 
6 #include <linux/bsearch.h>
7 #include <linux/fs.h>
8 #include <linux/file.h>
9 #include <linux/sort.h>
10 #include <linux/mount.h>
11 #include <linux/xattr.h>
12 #include <linux/posix_acl_xattr.h>
13 #include <linux/radix-tree.h>
14 #include <linux/vmalloc.h>
15 #include <linux/string.h>
16 #include <linux/compat.h>
17 #include <linux/crc32c.h>
18 
19 #include "send.h"
20 #include "backref.h"
21 #include "locking.h"
22 #include "disk-io.h"
23 #include "btrfs_inode.h"
24 #include "transaction.h"
25 #include "compression.h"
26 #include "xattr.h"
27 #include "print-tree.h"
28 
29 /*
30  * Maximum number of references an extent can have in order for us to attempt to
31  * issue clone operations instead of write operations. This currently exists to
32  * avoid hitting limitations of the backreference walking code (taking a lot of
33  * time and using too much memory for extents with large number of references).
34  */
35 #define SEND_MAX_EXTENT_REFS	64
36 
37 /*
38  * A fs_path is a helper to dynamically build path names with unknown size.
39  * It reallocates the internal buffer on demand.
40  * It allows fast adding of path elements on the right side (normal path) and
41  * fast adding to the left side (reversed path). A reversed path can also be
42  * unreversed if needed.
43  */
44 struct fs_path {
45 	union {
46 		struct {
47 			char *start;
48 			char *end;
49 
50 			char *buf;
51 			unsigned short buf_len:15;
52 			unsigned short reversed:1;
53 			char inline_buf[];
54 		};
55 		/*
56 		 * Average path length does not exceed 200 bytes, we'll have
57 		 * better packing in the slab and higher chance to satisfy
58 		 * a allocation later during send.
59 		 */
60 		char pad[256];
61 	};
62 };
63 #define FS_PATH_INLINE_SIZE \
64 	(sizeof(struct fs_path) - offsetof(struct fs_path, inline_buf))
65 
66 
67 /* reused for each extent */
68 struct clone_root {
69 	struct btrfs_root *root;
70 	u64 ino;
71 	u64 offset;
72 
73 	u64 found_refs;
74 };
75 
76 #define SEND_CTX_MAX_NAME_CACHE_SIZE 128
77 #define SEND_CTX_NAME_CACHE_CLEAN_SIZE (SEND_CTX_MAX_NAME_CACHE_SIZE * 2)
78 
79 struct send_ctx {
80 	struct file *send_filp;
81 	loff_t send_off;
82 	char *send_buf;
83 	u32 send_size;
84 	u32 send_max_size;
85 	u64 total_send_size;
86 	u64 cmd_send_size[BTRFS_SEND_C_MAX + 1];
87 	u64 flags;	/* 'flags' member of btrfs_ioctl_send_args is u64 */
88 
89 	struct btrfs_root *send_root;
90 	struct btrfs_root *parent_root;
91 	struct clone_root *clone_roots;
92 	int clone_roots_cnt;
93 
94 	/* current state of the compare_tree call */
95 	struct btrfs_path *left_path;
96 	struct btrfs_path *right_path;
97 	struct btrfs_key *cmp_key;
98 
99 	/*
100 	 * Keep track of the generation of the last transaction that was used
101 	 * for relocating a block group. This is periodically checked in order
102 	 * to detect if a relocation happened since the last check, so that we
103 	 * don't operate on stale extent buffers for nodes (level >= 1) or on
104 	 * stale disk_bytenr values of file extent items.
105 	 */
106 	u64 last_reloc_trans;
107 
108 	/*
109 	 * infos of the currently processed inode. In case of deleted inodes,
110 	 * these are the values from the deleted inode.
111 	 */
112 	u64 cur_ino;
113 	u64 cur_inode_gen;
114 	int cur_inode_new;
115 	int cur_inode_new_gen;
116 	int cur_inode_deleted;
117 	u64 cur_inode_size;
118 	u64 cur_inode_mode;
119 	u64 cur_inode_rdev;
120 	u64 cur_inode_last_extent;
121 	u64 cur_inode_next_write_offset;
122 	bool ignore_cur_inode;
123 
124 	u64 send_progress;
125 
126 	struct list_head new_refs;
127 	struct list_head deleted_refs;
128 
129 	struct radix_tree_root name_cache;
130 	struct list_head name_cache_list;
131 	int name_cache_size;
132 
133 	struct file_ra_state ra;
134 
135 	/*
136 	 * We process inodes by their increasing order, so if before an
137 	 * incremental send we reverse the parent/child relationship of
138 	 * directories such that a directory with a lower inode number was
139 	 * the parent of a directory with a higher inode number, and the one
140 	 * becoming the new parent got renamed too, we can't rename/move the
141 	 * directory with lower inode number when we finish processing it - we
142 	 * must process the directory with higher inode number first, then
143 	 * rename/move it and then rename/move the directory with lower inode
144 	 * number. Example follows.
145 	 *
146 	 * Tree state when the first send was performed:
147 	 *
148 	 * .
149 	 * |-- a                   (ino 257)
150 	 *     |-- b               (ino 258)
151 	 *         |
152 	 *         |
153 	 *         |-- c           (ino 259)
154 	 *         |   |-- d       (ino 260)
155 	 *         |
156 	 *         |-- c2          (ino 261)
157 	 *
158 	 * Tree state when the second (incremental) send is performed:
159 	 *
160 	 * .
161 	 * |-- a                   (ino 257)
162 	 *     |-- b               (ino 258)
163 	 *         |-- c2          (ino 261)
164 	 *             |-- d2      (ino 260)
165 	 *                 |-- cc  (ino 259)
166 	 *
167 	 * The sequence of steps that lead to the second state was:
168 	 *
169 	 * mv /a/b/c/d /a/b/c2/d2
170 	 * mv /a/b/c /a/b/c2/d2/cc
171 	 *
172 	 * "c" has lower inode number, but we can't move it (2nd mv operation)
173 	 * before we move "d", which has higher inode number.
174 	 *
175 	 * So we just memorize which move/rename operations must be performed
176 	 * later when their respective parent is processed and moved/renamed.
177 	 */
178 
179 	/* Indexed by parent directory inode number. */
180 	struct rb_root pending_dir_moves;
181 
182 	/*
183 	 * Reverse index, indexed by the inode number of a directory that
184 	 * is waiting for the move/rename of its immediate parent before its
185 	 * own move/rename can be performed.
186 	 */
187 	struct rb_root waiting_dir_moves;
188 
189 	/*
190 	 * A directory that is going to be rm'ed might have a child directory
191 	 * which is in the pending directory moves index above. In this case,
192 	 * the directory can only be removed after the move/rename of its child
193 	 * is performed. Example:
194 	 *
195 	 * Parent snapshot:
196 	 *
197 	 * .                        (ino 256)
198 	 * |-- a/                   (ino 257)
199 	 *     |-- b/               (ino 258)
200 	 *         |-- c/           (ino 259)
201 	 *         |   |-- x/       (ino 260)
202 	 *         |
203 	 *         |-- y/           (ino 261)
204 	 *
205 	 * Send snapshot:
206 	 *
207 	 * .                        (ino 256)
208 	 * |-- a/                   (ino 257)
209 	 *     |-- b/               (ino 258)
210 	 *         |-- YY/          (ino 261)
211 	 *              |-- x/      (ino 260)
212 	 *
213 	 * Sequence of steps that lead to the send snapshot:
214 	 * rm -f /a/b/c/foo.txt
215 	 * mv /a/b/y /a/b/YY
216 	 * mv /a/b/c/x /a/b/YY
217 	 * rmdir /a/b/c
218 	 *
219 	 * When the child is processed, its move/rename is delayed until its
220 	 * parent is processed (as explained above), but all other operations
221 	 * like update utimes, chown, chgrp, etc, are performed and the paths
222 	 * that it uses for those operations must use the orphanized name of
223 	 * its parent (the directory we're going to rm later), so we need to
224 	 * memorize that name.
225 	 *
226 	 * Indexed by the inode number of the directory to be deleted.
227 	 */
228 	struct rb_root orphan_dirs;
229 };
230 
231 struct pending_dir_move {
232 	struct rb_node node;
233 	struct list_head list;
234 	u64 parent_ino;
235 	u64 ino;
236 	u64 gen;
237 	struct list_head update_refs;
238 };
239 
240 struct waiting_dir_move {
241 	struct rb_node node;
242 	u64 ino;
243 	/*
244 	 * There might be some directory that could not be removed because it
245 	 * was waiting for this directory inode to be moved first. Therefore
246 	 * after this directory is moved, we can try to rmdir the ino rmdir_ino.
247 	 */
248 	u64 rmdir_ino;
249 	u64 rmdir_gen;
250 	bool orphanized;
251 };
252 
253 struct orphan_dir_info {
254 	struct rb_node node;
255 	u64 ino;
256 	u64 gen;
257 	u64 last_dir_index_offset;
258 };
259 
260 struct name_cache_entry {
261 	struct list_head list;
262 	/*
263 	 * radix_tree has only 32bit entries but we need to handle 64bit inums.
264 	 * We use the lower 32bit of the 64bit inum to store it in the tree. If
265 	 * more then one inum would fall into the same entry, we use radix_list
266 	 * to store the additional entries. radix_list is also used to store
267 	 * entries where two entries have the same inum but different
268 	 * generations.
269 	 */
270 	struct list_head radix_list;
271 	u64 ino;
272 	u64 gen;
273 	u64 parent_ino;
274 	u64 parent_gen;
275 	int ret;
276 	int need_later_update;
277 	int name_len;
278 	char name[];
279 };
280 
281 #define ADVANCE							1
282 #define ADVANCE_ONLY_NEXT					-1
283 
284 enum btrfs_compare_tree_result {
285 	BTRFS_COMPARE_TREE_NEW,
286 	BTRFS_COMPARE_TREE_DELETED,
287 	BTRFS_COMPARE_TREE_CHANGED,
288 	BTRFS_COMPARE_TREE_SAME,
289 };
290 
291 __cold
inconsistent_snapshot_error(struct send_ctx * sctx,enum btrfs_compare_tree_result result,const char * what)292 static void inconsistent_snapshot_error(struct send_ctx *sctx,
293 					enum btrfs_compare_tree_result result,
294 					const char *what)
295 {
296 	const char *result_string;
297 
298 	switch (result) {
299 	case BTRFS_COMPARE_TREE_NEW:
300 		result_string = "new";
301 		break;
302 	case BTRFS_COMPARE_TREE_DELETED:
303 		result_string = "deleted";
304 		break;
305 	case BTRFS_COMPARE_TREE_CHANGED:
306 		result_string = "updated";
307 		break;
308 	case BTRFS_COMPARE_TREE_SAME:
309 		ASSERT(0);
310 		result_string = "unchanged";
311 		break;
312 	default:
313 		ASSERT(0);
314 		result_string = "unexpected";
315 	}
316 
317 	btrfs_err(sctx->send_root->fs_info,
318 		  "Send: inconsistent snapshot, found %s %s for inode %llu without updated inode item, send root is %llu, parent root is %llu",
319 		  result_string, what, sctx->cmp_key->objectid,
320 		  sctx->send_root->root_key.objectid,
321 		  (sctx->parent_root ?
322 		   sctx->parent_root->root_key.objectid : 0));
323 }
324 
325 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino);
326 
327 static struct waiting_dir_move *
328 get_waiting_dir_move(struct send_ctx *sctx, u64 ino);
329 
330 static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen);
331 
need_send_hole(struct send_ctx * sctx)332 static int need_send_hole(struct send_ctx *sctx)
333 {
334 	return (sctx->parent_root && !sctx->cur_inode_new &&
335 		!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted &&
336 		S_ISREG(sctx->cur_inode_mode));
337 }
338 
fs_path_reset(struct fs_path * p)339 static void fs_path_reset(struct fs_path *p)
340 {
341 	if (p->reversed) {
342 		p->start = p->buf + p->buf_len - 1;
343 		p->end = p->start;
344 		*p->start = 0;
345 	} else {
346 		p->start = p->buf;
347 		p->end = p->start;
348 		*p->start = 0;
349 	}
350 }
351 
fs_path_alloc(void)352 static struct fs_path *fs_path_alloc(void)
353 {
354 	struct fs_path *p;
355 
356 	p = kmalloc(sizeof(*p), GFP_KERNEL);
357 	if (!p)
358 		return NULL;
359 	p->reversed = 0;
360 	p->buf = p->inline_buf;
361 	p->buf_len = FS_PATH_INLINE_SIZE;
362 	fs_path_reset(p);
363 	return p;
364 }
365 
fs_path_alloc_reversed(void)366 static struct fs_path *fs_path_alloc_reversed(void)
367 {
368 	struct fs_path *p;
369 
370 	p = fs_path_alloc();
371 	if (!p)
372 		return NULL;
373 	p->reversed = 1;
374 	fs_path_reset(p);
375 	return p;
376 }
377 
fs_path_free(struct fs_path * p)378 static void fs_path_free(struct fs_path *p)
379 {
380 	if (!p)
381 		return;
382 	if (p->buf != p->inline_buf)
383 		kfree(p->buf);
384 	kfree(p);
385 }
386 
fs_path_len(struct fs_path * p)387 static int fs_path_len(struct fs_path *p)
388 {
389 	return p->end - p->start;
390 }
391 
fs_path_ensure_buf(struct fs_path * p,int len)392 static int fs_path_ensure_buf(struct fs_path *p, int len)
393 {
394 	char *tmp_buf;
395 	int path_len;
396 	int old_buf_len;
397 
398 	len++;
399 
400 	if (p->buf_len >= len)
401 		return 0;
402 
403 	if (len > PATH_MAX) {
404 		WARN_ON(1);
405 		return -ENOMEM;
406 	}
407 
408 	path_len = p->end - p->start;
409 	old_buf_len = p->buf_len;
410 
411 	/*
412 	 * First time the inline_buf does not suffice
413 	 */
414 	if (p->buf == p->inline_buf) {
415 		tmp_buf = kmalloc(len, GFP_KERNEL);
416 		if (tmp_buf)
417 			memcpy(tmp_buf, p->buf, old_buf_len);
418 	} else {
419 		tmp_buf = krealloc(p->buf, len, GFP_KERNEL);
420 	}
421 	if (!tmp_buf)
422 		return -ENOMEM;
423 	p->buf = tmp_buf;
424 	/*
425 	 * The real size of the buffer is bigger, this will let the fast path
426 	 * happen most of the time
427 	 */
428 	p->buf_len = ksize(p->buf);
429 
430 	if (p->reversed) {
431 		tmp_buf = p->buf + old_buf_len - path_len - 1;
432 		p->end = p->buf + p->buf_len - 1;
433 		p->start = p->end - path_len;
434 		memmove(p->start, tmp_buf, path_len + 1);
435 	} else {
436 		p->start = p->buf;
437 		p->end = p->start + path_len;
438 	}
439 	return 0;
440 }
441 
fs_path_prepare_for_add(struct fs_path * p,int name_len,char ** prepared)442 static int fs_path_prepare_for_add(struct fs_path *p, int name_len,
443 				   char **prepared)
444 {
445 	int ret;
446 	int new_len;
447 
448 	new_len = p->end - p->start + name_len;
449 	if (p->start != p->end)
450 		new_len++;
451 	ret = fs_path_ensure_buf(p, new_len);
452 	if (ret < 0)
453 		goto out;
454 
455 	if (p->reversed) {
456 		if (p->start != p->end)
457 			*--p->start = '/';
458 		p->start -= name_len;
459 		*prepared = p->start;
460 	} else {
461 		if (p->start != p->end)
462 			*p->end++ = '/';
463 		*prepared = p->end;
464 		p->end += name_len;
465 		*p->end = 0;
466 	}
467 
468 out:
469 	return ret;
470 }
471 
fs_path_add(struct fs_path * p,const char * name,int name_len)472 static int fs_path_add(struct fs_path *p, const char *name, int name_len)
473 {
474 	int ret;
475 	char *prepared;
476 
477 	ret = fs_path_prepare_for_add(p, name_len, &prepared);
478 	if (ret < 0)
479 		goto out;
480 	memcpy(prepared, name, name_len);
481 
482 out:
483 	return ret;
484 }
485 
fs_path_add_path(struct fs_path * p,struct fs_path * p2)486 static int fs_path_add_path(struct fs_path *p, struct fs_path *p2)
487 {
488 	int ret;
489 	char *prepared;
490 
491 	ret = fs_path_prepare_for_add(p, p2->end - p2->start, &prepared);
492 	if (ret < 0)
493 		goto out;
494 	memcpy(prepared, p2->start, p2->end - p2->start);
495 
496 out:
497 	return ret;
498 }
499 
fs_path_add_from_extent_buffer(struct fs_path * p,struct extent_buffer * eb,unsigned long off,int len)500 static int fs_path_add_from_extent_buffer(struct fs_path *p,
501 					  struct extent_buffer *eb,
502 					  unsigned long off, int len)
503 {
504 	int ret;
505 	char *prepared;
506 
507 	ret = fs_path_prepare_for_add(p, len, &prepared);
508 	if (ret < 0)
509 		goto out;
510 
511 	read_extent_buffer(eb, prepared, off, len);
512 
513 out:
514 	return ret;
515 }
516 
fs_path_copy(struct fs_path * p,struct fs_path * from)517 static int fs_path_copy(struct fs_path *p, struct fs_path *from)
518 {
519 	int ret;
520 
521 	p->reversed = from->reversed;
522 	fs_path_reset(p);
523 
524 	ret = fs_path_add_path(p, from);
525 
526 	return ret;
527 }
528 
529 
fs_path_unreverse(struct fs_path * p)530 static void fs_path_unreverse(struct fs_path *p)
531 {
532 	char *tmp;
533 	int len;
534 
535 	if (!p->reversed)
536 		return;
537 
538 	tmp = p->start;
539 	len = p->end - p->start;
540 	p->start = p->buf;
541 	p->end = p->start + len;
542 	memmove(p->start, tmp, len + 1);
543 	p->reversed = 0;
544 }
545 
alloc_path_for_send(void)546 static struct btrfs_path *alloc_path_for_send(void)
547 {
548 	struct btrfs_path *path;
549 
550 	path = btrfs_alloc_path();
551 	if (!path)
552 		return NULL;
553 	path->search_commit_root = 1;
554 	path->skip_locking = 1;
555 	path->need_commit_sem = 1;
556 	return path;
557 }
558 
write_buf(struct file * filp,const void * buf,u32 len,loff_t * off)559 static int write_buf(struct file *filp, const void *buf, u32 len, loff_t *off)
560 {
561 	int ret;
562 	u32 pos = 0;
563 
564 	while (pos < len) {
565 		ret = kernel_write(filp, buf + pos, len - pos, off);
566 		/* TODO handle that correctly */
567 		/*if (ret == -ERESTARTSYS) {
568 			continue;
569 		}*/
570 		if (ret < 0)
571 			return ret;
572 		if (ret == 0) {
573 			return -EIO;
574 		}
575 		pos += ret;
576 	}
577 
578 	return 0;
579 }
580 
tlv_put(struct send_ctx * sctx,u16 attr,const void * data,int len)581 static int tlv_put(struct send_ctx *sctx, u16 attr, const void *data, int len)
582 {
583 	struct btrfs_tlv_header *hdr;
584 	int total_len = sizeof(*hdr) + len;
585 	int left = sctx->send_max_size - sctx->send_size;
586 
587 	if (unlikely(left < total_len))
588 		return -EOVERFLOW;
589 
590 	hdr = (struct btrfs_tlv_header *) (sctx->send_buf + sctx->send_size);
591 	put_unaligned_le16(attr, &hdr->tlv_type);
592 	put_unaligned_le16(len, &hdr->tlv_len);
593 	memcpy(hdr + 1, data, len);
594 	sctx->send_size += total_len;
595 
596 	return 0;
597 }
598 
599 #define TLV_PUT_DEFINE_INT(bits) \
600 	static int tlv_put_u##bits(struct send_ctx *sctx,	 	\
601 			u##bits attr, u##bits value)			\
602 	{								\
603 		__le##bits __tmp = cpu_to_le##bits(value);		\
604 		return tlv_put(sctx, attr, &__tmp, sizeof(__tmp));	\
605 	}
606 
607 TLV_PUT_DEFINE_INT(64)
608 
tlv_put_string(struct send_ctx * sctx,u16 attr,const char * str,int len)609 static int tlv_put_string(struct send_ctx *sctx, u16 attr,
610 			  const char *str, int len)
611 {
612 	if (len == -1)
613 		len = strlen(str);
614 	return tlv_put(sctx, attr, str, len);
615 }
616 
tlv_put_uuid(struct send_ctx * sctx,u16 attr,const u8 * uuid)617 static int tlv_put_uuid(struct send_ctx *sctx, u16 attr,
618 			const u8 *uuid)
619 {
620 	return tlv_put(sctx, attr, uuid, BTRFS_UUID_SIZE);
621 }
622 
tlv_put_btrfs_timespec(struct send_ctx * sctx,u16 attr,struct extent_buffer * eb,struct btrfs_timespec * ts)623 static int tlv_put_btrfs_timespec(struct send_ctx *sctx, u16 attr,
624 				  struct extent_buffer *eb,
625 				  struct btrfs_timespec *ts)
626 {
627 	struct btrfs_timespec bts;
628 	read_extent_buffer(eb, &bts, (unsigned long)ts, sizeof(bts));
629 	return tlv_put(sctx, attr, &bts, sizeof(bts));
630 }
631 
632 
633 #define TLV_PUT(sctx, attrtype, data, attrlen) \
634 	do { \
635 		ret = tlv_put(sctx, attrtype, data, attrlen); \
636 		if (ret < 0) \
637 			goto tlv_put_failure; \
638 	} while (0)
639 
640 #define TLV_PUT_INT(sctx, attrtype, bits, value) \
641 	do { \
642 		ret = tlv_put_u##bits(sctx, attrtype, value); \
643 		if (ret < 0) \
644 			goto tlv_put_failure; \
645 	} while (0)
646 
647 #define TLV_PUT_U8(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 8, data)
648 #define TLV_PUT_U16(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 16, data)
649 #define TLV_PUT_U32(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 32, data)
650 #define TLV_PUT_U64(sctx, attrtype, data) TLV_PUT_INT(sctx, attrtype, 64, data)
651 #define TLV_PUT_STRING(sctx, attrtype, str, len) \
652 	do { \
653 		ret = tlv_put_string(sctx, attrtype, str, len); \
654 		if (ret < 0) \
655 			goto tlv_put_failure; \
656 	} while (0)
657 #define TLV_PUT_PATH(sctx, attrtype, p) \
658 	do { \
659 		ret = tlv_put_string(sctx, attrtype, p->start, \
660 			p->end - p->start); \
661 		if (ret < 0) \
662 			goto tlv_put_failure; \
663 	} while(0)
664 #define TLV_PUT_UUID(sctx, attrtype, uuid) \
665 	do { \
666 		ret = tlv_put_uuid(sctx, attrtype, uuid); \
667 		if (ret < 0) \
668 			goto tlv_put_failure; \
669 	} while (0)
670 #define TLV_PUT_BTRFS_TIMESPEC(sctx, attrtype, eb, ts) \
671 	do { \
672 		ret = tlv_put_btrfs_timespec(sctx, attrtype, eb, ts); \
673 		if (ret < 0) \
674 			goto tlv_put_failure; \
675 	} while (0)
676 
send_header(struct send_ctx * sctx)677 static int send_header(struct send_ctx *sctx)
678 {
679 	struct btrfs_stream_header hdr;
680 
681 	strcpy(hdr.magic, BTRFS_SEND_STREAM_MAGIC);
682 	hdr.version = cpu_to_le32(BTRFS_SEND_STREAM_VERSION);
683 
684 	return write_buf(sctx->send_filp, &hdr, sizeof(hdr),
685 					&sctx->send_off);
686 }
687 
688 /*
689  * For each command/item we want to send to userspace, we call this function.
690  */
begin_cmd(struct send_ctx * sctx,int cmd)691 static int begin_cmd(struct send_ctx *sctx, int cmd)
692 {
693 	struct btrfs_cmd_header *hdr;
694 
695 	if (WARN_ON(!sctx->send_buf))
696 		return -EINVAL;
697 
698 	BUG_ON(sctx->send_size);
699 
700 	sctx->send_size += sizeof(*hdr);
701 	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
702 	put_unaligned_le16(cmd, &hdr->cmd);
703 
704 	return 0;
705 }
706 
send_cmd(struct send_ctx * sctx)707 static int send_cmd(struct send_ctx *sctx)
708 {
709 	int ret;
710 	struct btrfs_cmd_header *hdr;
711 	u32 crc;
712 
713 	hdr = (struct btrfs_cmd_header *)sctx->send_buf;
714 	put_unaligned_le32(sctx->send_size - sizeof(*hdr), &hdr->len);
715 	put_unaligned_le32(0, &hdr->crc);
716 
717 	crc = btrfs_crc32c(0, (unsigned char *)sctx->send_buf, sctx->send_size);
718 	put_unaligned_le32(crc, &hdr->crc);
719 
720 	ret = write_buf(sctx->send_filp, sctx->send_buf, sctx->send_size,
721 					&sctx->send_off);
722 
723 	sctx->total_send_size += sctx->send_size;
724 	sctx->cmd_send_size[get_unaligned_le16(&hdr->cmd)] += sctx->send_size;
725 	sctx->send_size = 0;
726 
727 	return ret;
728 }
729 
730 /*
731  * Sends a move instruction to user space
732  */
send_rename(struct send_ctx * sctx,struct fs_path * from,struct fs_path * to)733 static int send_rename(struct send_ctx *sctx,
734 		     struct fs_path *from, struct fs_path *to)
735 {
736 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
737 	int ret;
738 
739 	btrfs_debug(fs_info, "send_rename %s -> %s", from->start, to->start);
740 
741 	ret = begin_cmd(sctx, BTRFS_SEND_C_RENAME);
742 	if (ret < 0)
743 		goto out;
744 
745 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, from);
746 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_TO, to);
747 
748 	ret = send_cmd(sctx);
749 
750 tlv_put_failure:
751 out:
752 	return ret;
753 }
754 
755 /*
756  * Sends a link instruction to user space
757  */
send_link(struct send_ctx * sctx,struct fs_path * path,struct fs_path * lnk)758 static int send_link(struct send_ctx *sctx,
759 		     struct fs_path *path, struct fs_path *lnk)
760 {
761 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
762 	int ret;
763 
764 	btrfs_debug(fs_info, "send_link %s -> %s", path->start, lnk->start);
765 
766 	ret = begin_cmd(sctx, BTRFS_SEND_C_LINK);
767 	if (ret < 0)
768 		goto out;
769 
770 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
771 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, lnk);
772 
773 	ret = send_cmd(sctx);
774 
775 tlv_put_failure:
776 out:
777 	return ret;
778 }
779 
780 /*
781  * Sends an unlink instruction to user space
782  */
send_unlink(struct send_ctx * sctx,struct fs_path * path)783 static int send_unlink(struct send_ctx *sctx, struct fs_path *path)
784 {
785 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
786 	int ret;
787 
788 	btrfs_debug(fs_info, "send_unlink %s", path->start);
789 
790 	ret = begin_cmd(sctx, BTRFS_SEND_C_UNLINK);
791 	if (ret < 0)
792 		goto out;
793 
794 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
795 
796 	ret = send_cmd(sctx);
797 
798 tlv_put_failure:
799 out:
800 	return ret;
801 }
802 
803 /*
804  * Sends a rmdir instruction to user space
805  */
send_rmdir(struct send_ctx * sctx,struct fs_path * path)806 static int send_rmdir(struct send_ctx *sctx, struct fs_path *path)
807 {
808 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
809 	int ret;
810 
811 	btrfs_debug(fs_info, "send_rmdir %s", path->start);
812 
813 	ret = begin_cmd(sctx, BTRFS_SEND_C_RMDIR);
814 	if (ret < 0)
815 		goto out;
816 
817 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
818 
819 	ret = send_cmd(sctx);
820 
821 tlv_put_failure:
822 out:
823 	return ret;
824 }
825 
826 /*
827  * Helper function to retrieve some fields from an inode item.
828  */
__get_inode_info(struct btrfs_root * root,struct btrfs_path * path,u64 ino,u64 * size,u64 * gen,u64 * mode,u64 * uid,u64 * gid,u64 * rdev)829 static int __get_inode_info(struct btrfs_root *root, struct btrfs_path *path,
830 			  u64 ino, u64 *size, u64 *gen, u64 *mode, u64 *uid,
831 			  u64 *gid, u64 *rdev)
832 {
833 	int ret;
834 	struct btrfs_inode_item *ii;
835 	struct btrfs_key key;
836 
837 	key.objectid = ino;
838 	key.type = BTRFS_INODE_ITEM_KEY;
839 	key.offset = 0;
840 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
841 	if (ret) {
842 		if (ret > 0)
843 			ret = -ENOENT;
844 		return ret;
845 	}
846 
847 	ii = btrfs_item_ptr(path->nodes[0], path->slots[0],
848 			struct btrfs_inode_item);
849 	if (size)
850 		*size = btrfs_inode_size(path->nodes[0], ii);
851 	if (gen)
852 		*gen = btrfs_inode_generation(path->nodes[0], ii);
853 	if (mode)
854 		*mode = btrfs_inode_mode(path->nodes[0], ii);
855 	if (uid)
856 		*uid = btrfs_inode_uid(path->nodes[0], ii);
857 	if (gid)
858 		*gid = btrfs_inode_gid(path->nodes[0], ii);
859 	if (rdev)
860 		*rdev = btrfs_inode_rdev(path->nodes[0], ii);
861 
862 	return ret;
863 }
864 
get_inode_info(struct btrfs_root * root,u64 ino,u64 * size,u64 * gen,u64 * mode,u64 * uid,u64 * gid,u64 * rdev)865 static int get_inode_info(struct btrfs_root *root,
866 			  u64 ino, u64 *size, u64 *gen,
867 			  u64 *mode, u64 *uid, u64 *gid,
868 			  u64 *rdev)
869 {
870 	struct btrfs_path *path;
871 	int ret;
872 
873 	path = alloc_path_for_send();
874 	if (!path)
875 		return -ENOMEM;
876 	ret = __get_inode_info(root, path, ino, size, gen, mode, uid, gid,
877 			       rdev);
878 	btrfs_free_path(path);
879 	return ret;
880 }
881 
882 typedef int (*iterate_inode_ref_t)(int num, u64 dir, int index,
883 				   struct fs_path *p,
884 				   void *ctx);
885 
886 /*
887  * Helper function to iterate the entries in ONE btrfs_inode_ref or
888  * btrfs_inode_extref.
889  * The iterate callback may return a non zero value to stop iteration. This can
890  * be a negative value for error codes or 1 to simply stop it.
891  *
892  * path must point to the INODE_REF or INODE_EXTREF when called.
893  */
iterate_inode_ref(struct btrfs_root * root,struct btrfs_path * path,struct btrfs_key * found_key,int resolve,iterate_inode_ref_t iterate,void * ctx)894 static int iterate_inode_ref(struct btrfs_root *root, struct btrfs_path *path,
895 			     struct btrfs_key *found_key, int resolve,
896 			     iterate_inode_ref_t iterate, void *ctx)
897 {
898 	struct extent_buffer *eb = path->nodes[0];
899 	struct btrfs_item *item;
900 	struct btrfs_inode_ref *iref;
901 	struct btrfs_inode_extref *extref;
902 	struct btrfs_path *tmp_path;
903 	struct fs_path *p;
904 	u32 cur = 0;
905 	u32 total;
906 	int slot = path->slots[0];
907 	u32 name_len;
908 	char *start;
909 	int ret = 0;
910 	int num = 0;
911 	int index;
912 	u64 dir;
913 	unsigned long name_off;
914 	unsigned long elem_size;
915 	unsigned long ptr;
916 
917 	p = fs_path_alloc_reversed();
918 	if (!p)
919 		return -ENOMEM;
920 
921 	tmp_path = alloc_path_for_send();
922 	if (!tmp_path) {
923 		fs_path_free(p);
924 		return -ENOMEM;
925 	}
926 
927 
928 	if (found_key->type == BTRFS_INODE_REF_KEY) {
929 		ptr = (unsigned long)btrfs_item_ptr(eb, slot,
930 						    struct btrfs_inode_ref);
931 		item = btrfs_item_nr(slot);
932 		total = btrfs_item_size(eb, item);
933 		elem_size = sizeof(*iref);
934 	} else {
935 		ptr = btrfs_item_ptr_offset(eb, slot);
936 		total = btrfs_item_size_nr(eb, slot);
937 		elem_size = sizeof(*extref);
938 	}
939 
940 	while (cur < total) {
941 		fs_path_reset(p);
942 
943 		if (found_key->type == BTRFS_INODE_REF_KEY) {
944 			iref = (struct btrfs_inode_ref *)(ptr + cur);
945 			name_len = btrfs_inode_ref_name_len(eb, iref);
946 			name_off = (unsigned long)(iref + 1);
947 			index = btrfs_inode_ref_index(eb, iref);
948 			dir = found_key->offset;
949 		} else {
950 			extref = (struct btrfs_inode_extref *)(ptr + cur);
951 			name_len = btrfs_inode_extref_name_len(eb, extref);
952 			name_off = (unsigned long)&extref->name;
953 			index = btrfs_inode_extref_index(eb, extref);
954 			dir = btrfs_inode_extref_parent(eb, extref);
955 		}
956 
957 		if (resolve) {
958 			start = btrfs_ref_to_path(root, tmp_path, name_len,
959 						  name_off, eb, dir,
960 						  p->buf, p->buf_len);
961 			if (IS_ERR(start)) {
962 				ret = PTR_ERR(start);
963 				goto out;
964 			}
965 			if (start < p->buf) {
966 				/* overflow , try again with larger buffer */
967 				ret = fs_path_ensure_buf(p,
968 						p->buf_len + p->buf - start);
969 				if (ret < 0)
970 					goto out;
971 				start = btrfs_ref_to_path(root, tmp_path,
972 							  name_len, name_off,
973 							  eb, dir,
974 							  p->buf, p->buf_len);
975 				if (IS_ERR(start)) {
976 					ret = PTR_ERR(start);
977 					goto out;
978 				}
979 				BUG_ON(start < p->buf);
980 			}
981 			p->start = start;
982 		} else {
983 			ret = fs_path_add_from_extent_buffer(p, eb, name_off,
984 							     name_len);
985 			if (ret < 0)
986 				goto out;
987 		}
988 
989 		cur += elem_size + name_len;
990 		ret = iterate(num, dir, index, p, ctx);
991 		if (ret)
992 			goto out;
993 		num++;
994 	}
995 
996 out:
997 	btrfs_free_path(tmp_path);
998 	fs_path_free(p);
999 	return ret;
1000 }
1001 
1002 typedef int (*iterate_dir_item_t)(int num, struct btrfs_key *di_key,
1003 				  const char *name, int name_len,
1004 				  const char *data, int data_len,
1005 				  u8 type, void *ctx);
1006 
1007 /*
1008  * Helper function to iterate the entries in ONE btrfs_dir_item.
1009  * The iterate callback may return a non zero value to stop iteration. This can
1010  * be a negative value for error codes or 1 to simply stop it.
1011  *
1012  * path must point to the dir item when called.
1013  */
iterate_dir_item(struct btrfs_root * root,struct btrfs_path * path,iterate_dir_item_t iterate,void * ctx)1014 static int iterate_dir_item(struct btrfs_root *root, struct btrfs_path *path,
1015 			    iterate_dir_item_t iterate, void *ctx)
1016 {
1017 	int ret = 0;
1018 	struct extent_buffer *eb;
1019 	struct btrfs_item *item;
1020 	struct btrfs_dir_item *di;
1021 	struct btrfs_key di_key;
1022 	char *buf = NULL;
1023 	int buf_len;
1024 	u32 name_len;
1025 	u32 data_len;
1026 	u32 cur;
1027 	u32 len;
1028 	u32 total;
1029 	int slot;
1030 	int num;
1031 	u8 type;
1032 
1033 	/*
1034 	 * Start with a small buffer (1 page). If later we end up needing more
1035 	 * space, which can happen for xattrs on a fs with a leaf size greater
1036 	 * then the page size, attempt to increase the buffer. Typically xattr
1037 	 * values are small.
1038 	 */
1039 	buf_len = PATH_MAX;
1040 	buf = kmalloc(buf_len, GFP_KERNEL);
1041 	if (!buf) {
1042 		ret = -ENOMEM;
1043 		goto out;
1044 	}
1045 
1046 	eb = path->nodes[0];
1047 	slot = path->slots[0];
1048 	item = btrfs_item_nr(slot);
1049 	di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
1050 	cur = 0;
1051 	len = 0;
1052 	total = btrfs_item_size(eb, item);
1053 
1054 	num = 0;
1055 	while (cur < total) {
1056 		name_len = btrfs_dir_name_len(eb, di);
1057 		data_len = btrfs_dir_data_len(eb, di);
1058 		type = btrfs_dir_type(eb, di);
1059 		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
1060 
1061 		if (type == BTRFS_FT_XATTR) {
1062 			if (name_len > XATTR_NAME_MAX) {
1063 				ret = -ENAMETOOLONG;
1064 				goto out;
1065 			}
1066 			if (name_len + data_len >
1067 					BTRFS_MAX_XATTR_SIZE(root->fs_info)) {
1068 				ret = -E2BIG;
1069 				goto out;
1070 			}
1071 		} else {
1072 			/*
1073 			 * Path too long
1074 			 */
1075 			if (name_len + data_len > PATH_MAX) {
1076 				ret = -ENAMETOOLONG;
1077 				goto out;
1078 			}
1079 		}
1080 
1081 		if (name_len + data_len > buf_len) {
1082 			buf_len = name_len + data_len;
1083 			if (is_vmalloc_addr(buf)) {
1084 				vfree(buf);
1085 				buf = NULL;
1086 			} else {
1087 				char *tmp = krealloc(buf, buf_len,
1088 						GFP_KERNEL | __GFP_NOWARN);
1089 
1090 				if (!tmp)
1091 					kfree(buf);
1092 				buf = tmp;
1093 			}
1094 			if (!buf) {
1095 				buf = kvmalloc(buf_len, GFP_KERNEL);
1096 				if (!buf) {
1097 					ret = -ENOMEM;
1098 					goto out;
1099 				}
1100 			}
1101 		}
1102 
1103 		read_extent_buffer(eb, buf, (unsigned long)(di + 1),
1104 				name_len + data_len);
1105 
1106 		len = sizeof(*di) + name_len + data_len;
1107 		di = (struct btrfs_dir_item *)((char *)di + len);
1108 		cur += len;
1109 
1110 		ret = iterate(num, &di_key, buf, name_len, buf + name_len,
1111 				data_len, type, ctx);
1112 		if (ret < 0)
1113 			goto out;
1114 		if (ret) {
1115 			ret = 0;
1116 			goto out;
1117 		}
1118 
1119 		num++;
1120 	}
1121 
1122 out:
1123 	kvfree(buf);
1124 	return ret;
1125 }
1126 
__copy_first_ref(int num,u64 dir,int index,struct fs_path * p,void * ctx)1127 static int __copy_first_ref(int num, u64 dir, int index,
1128 			    struct fs_path *p, void *ctx)
1129 {
1130 	int ret;
1131 	struct fs_path *pt = ctx;
1132 
1133 	ret = fs_path_copy(pt, p);
1134 	if (ret < 0)
1135 		return ret;
1136 
1137 	/* we want the first only */
1138 	return 1;
1139 }
1140 
1141 /*
1142  * Retrieve the first path of an inode. If an inode has more then one
1143  * ref/hardlink, this is ignored.
1144  */
get_inode_path(struct btrfs_root * root,u64 ino,struct fs_path * path)1145 static int get_inode_path(struct btrfs_root *root,
1146 			  u64 ino, struct fs_path *path)
1147 {
1148 	int ret;
1149 	struct btrfs_key key, found_key;
1150 	struct btrfs_path *p;
1151 
1152 	p = alloc_path_for_send();
1153 	if (!p)
1154 		return -ENOMEM;
1155 
1156 	fs_path_reset(path);
1157 
1158 	key.objectid = ino;
1159 	key.type = BTRFS_INODE_REF_KEY;
1160 	key.offset = 0;
1161 
1162 	ret = btrfs_search_slot_for_read(root, &key, p, 1, 0);
1163 	if (ret < 0)
1164 		goto out;
1165 	if (ret) {
1166 		ret = 1;
1167 		goto out;
1168 	}
1169 	btrfs_item_key_to_cpu(p->nodes[0], &found_key, p->slots[0]);
1170 	if (found_key.objectid != ino ||
1171 	    (found_key.type != BTRFS_INODE_REF_KEY &&
1172 	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
1173 		ret = -ENOENT;
1174 		goto out;
1175 	}
1176 
1177 	ret = iterate_inode_ref(root, p, &found_key, 1,
1178 				__copy_first_ref, path);
1179 	if (ret < 0)
1180 		goto out;
1181 	ret = 0;
1182 
1183 out:
1184 	btrfs_free_path(p);
1185 	return ret;
1186 }
1187 
1188 struct backref_ctx {
1189 	struct send_ctx *sctx;
1190 
1191 	/* number of total found references */
1192 	u64 found;
1193 
1194 	/*
1195 	 * used for clones found in send_root. clones found behind cur_objectid
1196 	 * and cur_offset are not considered as allowed clones.
1197 	 */
1198 	u64 cur_objectid;
1199 	u64 cur_offset;
1200 
1201 	/* may be truncated in case it's the last extent in a file */
1202 	u64 extent_len;
1203 
1204 	/* Just to check for bugs in backref resolving */
1205 	int found_itself;
1206 };
1207 
__clone_root_cmp_bsearch(const void * key,const void * elt)1208 static int __clone_root_cmp_bsearch(const void *key, const void *elt)
1209 {
1210 	u64 root = (u64)(uintptr_t)key;
1211 	const struct clone_root *cr = elt;
1212 
1213 	if (root < cr->root->root_key.objectid)
1214 		return -1;
1215 	if (root > cr->root->root_key.objectid)
1216 		return 1;
1217 	return 0;
1218 }
1219 
__clone_root_cmp_sort(const void * e1,const void * e2)1220 static int __clone_root_cmp_sort(const void *e1, const void *e2)
1221 {
1222 	const struct clone_root *cr1 = e1;
1223 	const struct clone_root *cr2 = e2;
1224 
1225 	if (cr1->root->root_key.objectid < cr2->root->root_key.objectid)
1226 		return -1;
1227 	if (cr1->root->root_key.objectid > cr2->root->root_key.objectid)
1228 		return 1;
1229 	return 0;
1230 }
1231 
1232 /*
1233  * Called for every backref that is found for the current extent.
1234  * Results are collected in sctx->clone_roots->ino/offset/found_refs
1235  */
__iterate_backrefs(u64 ino,u64 offset,u64 root,void * ctx_)1236 static int __iterate_backrefs(u64 ino, u64 offset, u64 root, void *ctx_)
1237 {
1238 	struct backref_ctx *bctx = ctx_;
1239 	struct clone_root *found;
1240 
1241 	/* First check if the root is in the list of accepted clone sources */
1242 	found = bsearch((void *)(uintptr_t)root, bctx->sctx->clone_roots,
1243 			bctx->sctx->clone_roots_cnt,
1244 			sizeof(struct clone_root),
1245 			__clone_root_cmp_bsearch);
1246 	if (!found)
1247 		return 0;
1248 
1249 	if (found->root == bctx->sctx->send_root &&
1250 	    ino == bctx->cur_objectid &&
1251 	    offset == bctx->cur_offset) {
1252 		bctx->found_itself = 1;
1253 	}
1254 
1255 	/*
1256 	 * Make sure we don't consider clones from send_root that are
1257 	 * behind the current inode/offset.
1258 	 */
1259 	if (found->root == bctx->sctx->send_root) {
1260 		/*
1261 		 * If the source inode was not yet processed we can't issue a
1262 		 * clone operation, as the source extent does not exist yet at
1263 		 * the destination of the stream.
1264 		 */
1265 		if (ino > bctx->cur_objectid)
1266 			return 0;
1267 		/*
1268 		 * We clone from the inode currently being sent as long as the
1269 		 * source extent is already processed, otherwise we could try
1270 		 * to clone from an extent that does not exist yet at the
1271 		 * destination of the stream.
1272 		 */
1273 		if (ino == bctx->cur_objectid &&
1274 		    offset + bctx->extent_len >
1275 		    bctx->sctx->cur_inode_next_write_offset)
1276 			return 0;
1277 	}
1278 
1279 	bctx->found++;
1280 	found->found_refs++;
1281 	if (ino < found->ino) {
1282 		found->ino = ino;
1283 		found->offset = offset;
1284 	} else if (found->ino == ino) {
1285 		/*
1286 		 * same extent found more then once in the same file.
1287 		 */
1288 		if (found->offset > offset + bctx->extent_len)
1289 			found->offset = offset;
1290 	}
1291 
1292 	return 0;
1293 }
1294 
1295 /*
1296  * Given an inode, offset and extent item, it finds a good clone for a clone
1297  * instruction. Returns -ENOENT when none could be found. The function makes
1298  * sure that the returned clone is usable at the point where sending is at the
1299  * moment. This means, that no clones are accepted which lie behind the current
1300  * inode+offset.
1301  *
1302  * path must point to the extent item when called.
1303  */
find_extent_clone(struct send_ctx * sctx,struct btrfs_path * path,u64 ino,u64 data_offset,u64 ino_size,struct clone_root ** found)1304 static int find_extent_clone(struct send_ctx *sctx,
1305 			     struct btrfs_path *path,
1306 			     u64 ino, u64 data_offset,
1307 			     u64 ino_size,
1308 			     struct clone_root **found)
1309 {
1310 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
1311 	int ret;
1312 	int extent_type;
1313 	u64 logical;
1314 	u64 disk_byte;
1315 	u64 num_bytes;
1316 	u64 extent_item_pos;
1317 	u64 flags = 0;
1318 	struct btrfs_file_extent_item *fi;
1319 	struct extent_buffer *eb = path->nodes[0];
1320 	struct backref_ctx backref_ctx = {0};
1321 	struct clone_root *cur_clone_root;
1322 	struct btrfs_key found_key;
1323 	struct btrfs_path *tmp_path;
1324 	struct btrfs_extent_item *ei;
1325 	int compressed;
1326 	u32 i;
1327 
1328 	tmp_path = alloc_path_for_send();
1329 	if (!tmp_path)
1330 		return -ENOMEM;
1331 
1332 	/* We only use this path under the commit sem */
1333 	tmp_path->need_commit_sem = 0;
1334 
1335 	if (data_offset >= ino_size) {
1336 		/*
1337 		 * There may be extents that lie behind the file's size.
1338 		 * I at least had this in combination with snapshotting while
1339 		 * writing large files.
1340 		 */
1341 		ret = 0;
1342 		goto out;
1343 	}
1344 
1345 	fi = btrfs_item_ptr(eb, path->slots[0],
1346 			struct btrfs_file_extent_item);
1347 	extent_type = btrfs_file_extent_type(eb, fi);
1348 	if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
1349 		ret = -ENOENT;
1350 		goto out;
1351 	}
1352 	compressed = btrfs_file_extent_compression(eb, fi);
1353 
1354 	num_bytes = btrfs_file_extent_num_bytes(eb, fi);
1355 	disk_byte = btrfs_file_extent_disk_bytenr(eb, fi);
1356 	if (disk_byte == 0) {
1357 		ret = -ENOENT;
1358 		goto out;
1359 	}
1360 	logical = disk_byte + btrfs_file_extent_offset(eb, fi);
1361 
1362 	down_read(&fs_info->commit_root_sem);
1363 	ret = extent_from_logical(fs_info, disk_byte, tmp_path,
1364 				  &found_key, &flags);
1365 	up_read(&fs_info->commit_root_sem);
1366 
1367 	if (ret < 0)
1368 		goto out;
1369 	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
1370 		ret = -EIO;
1371 		goto out;
1372 	}
1373 
1374 	ei = btrfs_item_ptr(tmp_path->nodes[0], tmp_path->slots[0],
1375 			    struct btrfs_extent_item);
1376 	/*
1377 	 * Backreference walking (iterate_extent_inodes() below) is currently
1378 	 * too expensive when an extent has a large number of references, both
1379 	 * in time spent and used memory. So for now just fallback to write
1380 	 * operations instead of clone operations when an extent has more than
1381 	 * a certain amount of references.
1382 	 */
1383 	if (btrfs_extent_refs(tmp_path->nodes[0], ei) > SEND_MAX_EXTENT_REFS) {
1384 		ret = -ENOENT;
1385 		goto out;
1386 	}
1387 	btrfs_release_path(tmp_path);
1388 
1389 	/*
1390 	 * Setup the clone roots.
1391 	 */
1392 	for (i = 0; i < sctx->clone_roots_cnt; i++) {
1393 		cur_clone_root = sctx->clone_roots + i;
1394 		cur_clone_root->ino = (u64)-1;
1395 		cur_clone_root->offset = 0;
1396 		cur_clone_root->found_refs = 0;
1397 	}
1398 
1399 	backref_ctx.sctx = sctx;
1400 	backref_ctx.found = 0;
1401 	backref_ctx.cur_objectid = ino;
1402 	backref_ctx.cur_offset = data_offset;
1403 	backref_ctx.found_itself = 0;
1404 	backref_ctx.extent_len = num_bytes;
1405 
1406 	/*
1407 	 * The last extent of a file may be too large due to page alignment.
1408 	 * We need to adjust extent_len in this case so that the checks in
1409 	 * __iterate_backrefs work.
1410 	 */
1411 	if (data_offset + num_bytes >= ino_size)
1412 		backref_ctx.extent_len = ino_size - data_offset;
1413 
1414 	/*
1415 	 * Now collect all backrefs.
1416 	 */
1417 	if (compressed == BTRFS_COMPRESS_NONE)
1418 		extent_item_pos = logical - found_key.objectid;
1419 	else
1420 		extent_item_pos = 0;
1421 	ret = iterate_extent_inodes(fs_info, found_key.objectid,
1422 				    extent_item_pos, 1, __iterate_backrefs,
1423 				    &backref_ctx, false);
1424 
1425 	if (ret < 0)
1426 		goto out;
1427 
1428 	down_read(&fs_info->commit_root_sem);
1429 	if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
1430 		/*
1431 		 * A transaction commit for a transaction in which block group
1432 		 * relocation was done just happened.
1433 		 * The disk_bytenr of the file extent item we processed is
1434 		 * possibly stale, referring to the extent's location before
1435 		 * relocation. So act as if we haven't found any clone sources
1436 		 * and fallback to write commands, which will read the correct
1437 		 * data from the new extent location. Otherwise we will fail
1438 		 * below because we haven't found our own back reference or we
1439 		 * could be getting incorrect sources in case the old extent
1440 		 * was already reallocated after the relocation.
1441 		 */
1442 		up_read(&fs_info->commit_root_sem);
1443 		ret = -ENOENT;
1444 		goto out;
1445 	}
1446 	up_read(&fs_info->commit_root_sem);
1447 
1448 	if (!backref_ctx.found_itself) {
1449 		/* found a bug in backref code? */
1450 		ret = -EIO;
1451 		btrfs_err(fs_info,
1452 			  "did not find backref in send_root. inode=%llu, offset=%llu, disk_byte=%llu found extent=%llu",
1453 			  ino, data_offset, disk_byte, found_key.objectid);
1454 		goto out;
1455 	}
1456 
1457 	btrfs_debug(fs_info,
1458 		    "find_extent_clone: data_offset=%llu, ino=%llu, num_bytes=%llu, logical=%llu",
1459 		    data_offset, ino, num_bytes, logical);
1460 
1461 	if (!backref_ctx.found)
1462 		btrfs_debug(fs_info, "no clones found");
1463 
1464 	cur_clone_root = NULL;
1465 	for (i = 0; i < sctx->clone_roots_cnt; i++) {
1466 		if (sctx->clone_roots[i].found_refs) {
1467 			if (!cur_clone_root)
1468 				cur_clone_root = sctx->clone_roots + i;
1469 			else if (sctx->clone_roots[i].root == sctx->send_root)
1470 				/* prefer clones from send_root over others */
1471 				cur_clone_root = sctx->clone_roots + i;
1472 		}
1473 
1474 	}
1475 
1476 	if (cur_clone_root) {
1477 		*found = cur_clone_root;
1478 		ret = 0;
1479 	} else {
1480 		ret = -ENOENT;
1481 	}
1482 
1483 out:
1484 	btrfs_free_path(tmp_path);
1485 	return ret;
1486 }
1487 
read_symlink(struct btrfs_root * root,u64 ino,struct fs_path * dest)1488 static int read_symlink(struct btrfs_root *root,
1489 			u64 ino,
1490 			struct fs_path *dest)
1491 {
1492 	int ret;
1493 	struct btrfs_path *path;
1494 	struct btrfs_key key;
1495 	struct btrfs_file_extent_item *ei;
1496 	u8 type;
1497 	u8 compression;
1498 	unsigned long off;
1499 	int len;
1500 
1501 	path = alloc_path_for_send();
1502 	if (!path)
1503 		return -ENOMEM;
1504 
1505 	key.objectid = ino;
1506 	key.type = BTRFS_EXTENT_DATA_KEY;
1507 	key.offset = 0;
1508 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
1509 	if (ret < 0)
1510 		goto out;
1511 	if (ret) {
1512 		/*
1513 		 * An empty symlink inode. Can happen in rare error paths when
1514 		 * creating a symlink (transaction committed before the inode
1515 		 * eviction handler removed the symlink inode items and a crash
1516 		 * happened in between or the subvol was snapshoted in between).
1517 		 * Print an informative message to dmesg/syslog so that the user
1518 		 * can delete the symlink.
1519 		 */
1520 		btrfs_err(root->fs_info,
1521 			  "Found empty symlink inode %llu at root %llu",
1522 			  ino, root->root_key.objectid);
1523 		ret = -EIO;
1524 		goto out;
1525 	}
1526 
1527 	ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
1528 			struct btrfs_file_extent_item);
1529 	type = btrfs_file_extent_type(path->nodes[0], ei);
1530 	compression = btrfs_file_extent_compression(path->nodes[0], ei);
1531 	BUG_ON(type != BTRFS_FILE_EXTENT_INLINE);
1532 	BUG_ON(compression);
1533 
1534 	off = btrfs_file_extent_inline_start(ei);
1535 	len = btrfs_file_extent_ram_bytes(path->nodes[0], ei);
1536 
1537 	ret = fs_path_add_from_extent_buffer(dest, path->nodes[0], off, len);
1538 
1539 out:
1540 	btrfs_free_path(path);
1541 	return ret;
1542 }
1543 
1544 /*
1545  * Helper function to generate a file name that is unique in the root of
1546  * send_root and parent_root. This is used to generate names for orphan inodes.
1547  */
gen_unique_name(struct send_ctx * sctx,u64 ino,u64 gen,struct fs_path * dest)1548 static int gen_unique_name(struct send_ctx *sctx,
1549 			   u64 ino, u64 gen,
1550 			   struct fs_path *dest)
1551 {
1552 	int ret = 0;
1553 	struct btrfs_path *path;
1554 	struct btrfs_dir_item *di;
1555 	char tmp[64];
1556 	int len;
1557 	u64 idx = 0;
1558 
1559 	path = alloc_path_for_send();
1560 	if (!path)
1561 		return -ENOMEM;
1562 
1563 	while (1) {
1564 		len = snprintf(tmp, sizeof(tmp), "o%llu-%llu-%llu",
1565 				ino, gen, idx);
1566 		ASSERT(len < sizeof(tmp));
1567 
1568 		di = btrfs_lookup_dir_item(NULL, sctx->send_root,
1569 				path, BTRFS_FIRST_FREE_OBJECTID,
1570 				tmp, strlen(tmp), 0);
1571 		btrfs_release_path(path);
1572 		if (IS_ERR(di)) {
1573 			ret = PTR_ERR(di);
1574 			goto out;
1575 		}
1576 		if (di) {
1577 			/* not unique, try again */
1578 			idx++;
1579 			continue;
1580 		}
1581 
1582 		if (!sctx->parent_root) {
1583 			/* unique */
1584 			ret = 0;
1585 			break;
1586 		}
1587 
1588 		di = btrfs_lookup_dir_item(NULL, sctx->parent_root,
1589 				path, BTRFS_FIRST_FREE_OBJECTID,
1590 				tmp, strlen(tmp), 0);
1591 		btrfs_release_path(path);
1592 		if (IS_ERR(di)) {
1593 			ret = PTR_ERR(di);
1594 			goto out;
1595 		}
1596 		if (di) {
1597 			/* not unique, try again */
1598 			idx++;
1599 			continue;
1600 		}
1601 		/* unique */
1602 		break;
1603 	}
1604 
1605 	ret = fs_path_add(dest, tmp, strlen(tmp));
1606 
1607 out:
1608 	btrfs_free_path(path);
1609 	return ret;
1610 }
1611 
1612 enum inode_state {
1613 	inode_state_no_change,
1614 	inode_state_will_create,
1615 	inode_state_did_create,
1616 	inode_state_will_delete,
1617 	inode_state_did_delete,
1618 };
1619 
get_cur_inode_state(struct send_ctx * sctx,u64 ino,u64 gen)1620 static int get_cur_inode_state(struct send_ctx *sctx, u64 ino, u64 gen)
1621 {
1622 	int ret;
1623 	int left_ret;
1624 	int right_ret;
1625 	u64 left_gen;
1626 	u64 right_gen;
1627 
1628 	ret = get_inode_info(sctx->send_root, ino, NULL, &left_gen, NULL, NULL,
1629 			NULL, NULL);
1630 	if (ret < 0 && ret != -ENOENT)
1631 		goto out;
1632 	left_ret = ret;
1633 
1634 	if (!sctx->parent_root) {
1635 		right_ret = -ENOENT;
1636 	} else {
1637 		ret = get_inode_info(sctx->parent_root, ino, NULL, &right_gen,
1638 				NULL, NULL, NULL, NULL);
1639 		if (ret < 0 && ret != -ENOENT)
1640 			goto out;
1641 		right_ret = ret;
1642 	}
1643 
1644 	if (!left_ret && !right_ret) {
1645 		if (left_gen == gen && right_gen == gen) {
1646 			ret = inode_state_no_change;
1647 		} else if (left_gen == gen) {
1648 			if (ino < sctx->send_progress)
1649 				ret = inode_state_did_create;
1650 			else
1651 				ret = inode_state_will_create;
1652 		} else if (right_gen == gen) {
1653 			if (ino < sctx->send_progress)
1654 				ret = inode_state_did_delete;
1655 			else
1656 				ret = inode_state_will_delete;
1657 		} else  {
1658 			ret = -ENOENT;
1659 		}
1660 	} else if (!left_ret) {
1661 		if (left_gen == gen) {
1662 			if (ino < sctx->send_progress)
1663 				ret = inode_state_did_create;
1664 			else
1665 				ret = inode_state_will_create;
1666 		} else {
1667 			ret = -ENOENT;
1668 		}
1669 	} else if (!right_ret) {
1670 		if (right_gen == gen) {
1671 			if (ino < sctx->send_progress)
1672 				ret = inode_state_did_delete;
1673 			else
1674 				ret = inode_state_will_delete;
1675 		} else {
1676 			ret = -ENOENT;
1677 		}
1678 	} else {
1679 		ret = -ENOENT;
1680 	}
1681 
1682 out:
1683 	return ret;
1684 }
1685 
is_inode_existent(struct send_ctx * sctx,u64 ino,u64 gen)1686 static int is_inode_existent(struct send_ctx *sctx, u64 ino, u64 gen)
1687 {
1688 	int ret;
1689 
1690 	if (ino == BTRFS_FIRST_FREE_OBJECTID)
1691 		return 1;
1692 
1693 	ret = get_cur_inode_state(sctx, ino, gen);
1694 	if (ret < 0)
1695 		goto out;
1696 
1697 	if (ret == inode_state_no_change ||
1698 	    ret == inode_state_did_create ||
1699 	    ret == inode_state_will_delete)
1700 		ret = 1;
1701 	else
1702 		ret = 0;
1703 
1704 out:
1705 	return ret;
1706 }
1707 
1708 /*
1709  * Helper function to lookup a dir item in a dir.
1710  */
lookup_dir_item_inode(struct btrfs_root * root,u64 dir,const char * name,int name_len,u64 * found_inode,u8 * found_type)1711 static int lookup_dir_item_inode(struct btrfs_root *root,
1712 				 u64 dir, const char *name, int name_len,
1713 				 u64 *found_inode,
1714 				 u8 *found_type)
1715 {
1716 	int ret = 0;
1717 	struct btrfs_dir_item *di;
1718 	struct btrfs_key key;
1719 	struct btrfs_path *path;
1720 
1721 	path = alloc_path_for_send();
1722 	if (!path)
1723 		return -ENOMEM;
1724 
1725 	di = btrfs_lookup_dir_item(NULL, root, path,
1726 			dir, name, name_len, 0);
1727 	if (IS_ERR_OR_NULL(di)) {
1728 		ret = di ? PTR_ERR(di) : -ENOENT;
1729 		goto out;
1730 	}
1731 	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
1732 	if (key.type == BTRFS_ROOT_ITEM_KEY) {
1733 		ret = -ENOENT;
1734 		goto out;
1735 	}
1736 	*found_inode = key.objectid;
1737 	*found_type = btrfs_dir_type(path->nodes[0], di);
1738 
1739 out:
1740 	btrfs_free_path(path);
1741 	return ret;
1742 }
1743 
1744 /*
1745  * Looks up the first btrfs_inode_ref of a given ino. It returns the parent dir,
1746  * generation of the parent dir and the name of the dir entry.
1747  */
get_first_ref(struct btrfs_root * root,u64 ino,u64 * dir,u64 * dir_gen,struct fs_path * name)1748 static int get_first_ref(struct btrfs_root *root, u64 ino,
1749 			 u64 *dir, u64 *dir_gen, struct fs_path *name)
1750 {
1751 	int ret;
1752 	struct btrfs_key key;
1753 	struct btrfs_key found_key;
1754 	struct btrfs_path *path;
1755 	int len;
1756 	u64 parent_dir;
1757 
1758 	path = alloc_path_for_send();
1759 	if (!path)
1760 		return -ENOMEM;
1761 
1762 	key.objectid = ino;
1763 	key.type = BTRFS_INODE_REF_KEY;
1764 	key.offset = 0;
1765 
1766 	ret = btrfs_search_slot_for_read(root, &key, path, 1, 0);
1767 	if (ret < 0)
1768 		goto out;
1769 	if (!ret)
1770 		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
1771 				path->slots[0]);
1772 	if (ret || found_key.objectid != ino ||
1773 	    (found_key.type != BTRFS_INODE_REF_KEY &&
1774 	     found_key.type != BTRFS_INODE_EXTREF_KEY)) {
1775 		ret = -ENOENT;
1776 		goto out;
1777 	}
1778 
1779 	if (found_key.type == BTRFS_INODE_REF_KEY) {
1780 		struct btrfs_inode_ref *iref;
1781 		iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1782 				      struct btrfs_inode_ref);
1783 		len = btrfs_inode_ref_name_len(path->nodes[0], iref);
1784 		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
1785 						     (unsigned long)(iref + 1),
1786 						     len);
1787 		parent_dir = found_key.offset;
1788 	} else {
1789 		struct btrfs_inode_extref *extref;
1790 		extref = btrfs_item_ptr(path->nodes[0], path->slots[0],
1791 					struct btrfs_inode_extref);
1792 		len = btrfs_inode_extref_name_len(path->nodes[0], extref);
1793 		ret = fs_path_add_from_extent_buffer(name, path->nodes[0],
1794 					(unsigned long)&extref->name, len);
1795 		parent_dir = btrfs_inode_extref_parent(path->nodes[0], extref);
1796 	}
1797 	if (ret < 0)
1798 		goto out;
1799 	btrfs_release_path(path);
1800 
1801 	if (dir_gen) {
1802 		ret = get_inode_info(root, parent_dir, NULL, dir_gen, NULL,
1803 				     NULL, NULL, NULL);
1804 		if (ret < 0)
1805 			goto out;
1806 	}
1807 
1808 	*dir = parent_dir;
1809 
1810 out:
1811 	btrfs_free_path(path);
1812 	return ret;
1813 }
1814 
is_first_ref(struct btrfs_root * root,u64 ino,u64 dir,const char * name,int name_len)1815 static int is_first_ref(struct btrfs_root *root,
1816 			u64 ino, u64 dir,
1817 			const char *name, int name_len)
1818 {
1819 	int ret;
1820 	struct fs_path *tmp_name;
1821 	u64 tmp_dir;
1822 
1823 	tmp_name = fs_path_alloc();
1824 	if (!tmp_name)
1825 		return -ENOMEM;
1826 
1827 	ret = get_first_ref(root, ino, &tmp_dir, NULL, tmp_name);
1828 	if (ret < 0)
1829 		goto out;
1830 
1831 	if (dir != tmp_dir || name_len != fs_path_len(tmp_name)) {
1832 		ret = 0;
1833 		goto out;
1834 	}
1835 
1836 	ret = !memcmp(tmp_name->start, name, name_len);
1837 
1838 out:
1839 	fs_path_free(tmp_name);
1840 	return ret;
1841 }
1842 
1843 /*
1844  * Used by process_recorded_refs to determine if a new ref would overwrite an
1845  * already existing ref. In case it detects an overwrite, it returns the
1846  * inode/gen in who_ino/who_gen.
1847  * When an overwrite is detected, process_recorded_refs does proper orphanizing
1848  * to make sure later references to the overwritten inode are possible.
1849  * Orphanizing is however only required for the first ref of an inode.
1850  * process_recorded_refs does an additional is_first_ref check to see if
1851  * orphanizing is really required.
1852  */
will_overwrite_ref(struct send_ctx * sctx,u64 dir,u64 dir_gen,const char * name,int name_len,u64 * who_ino,u64 * who_gen,u64 * who_mode)1853 static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
1854 			      const char *name, int name_len,
1855 			      u64 *who_ino, u64 *who_gen, u64 *who_mode)
1856 {
1857 	int ret = 0;
1858 	u64 gen;
1859 	u64 other_inode = 0;
1860 	u8 other_type = 0;
1861 
1862 	if (!sctx->parent_root)
1863 		goto out;
1864 
1865 	ret = is_inode_existent(sctx, dir, dir_gen);
1866 	if (ret <= 0)
1867 		goto out;
1868 
1869 	/*
1870 	 * If we have a parent root we need to verify that the parent dir was
1871 	 * not deleted and then re-created, if it was then we have no overwrite
1872 	 * and we can just unlink this entry.
1873 	 */
1874 	if (sctx->parent_root && dir != BTRFS_FIRST_FREE_OBJECTID) {
1875 		ret = get_inode_info(sctx->parent_root, dir, NULL, &gen, NULL,
1876 				     NULL, NULL, NULL);
1877 		if (ret < 0 && ret != -ENOENT)
1878 			goto out;
1879 		if (ret) {
1880 			ret = 0;
1881 			goto out;
1882 		}
1883 		if (gen != dir_gen)
1884 			goto out;
1885 	}
1886 
1887 	ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
1888 			&other_inode, &other_type);
1889 	if (ret < 0 && ret != -ENOENT)
1890 		goto out;
1891 	if (ret) {
1892 		ret = 0;
1893 		goto out;
1894 	}
1895 
1896 	/*
1897 	 * Check if the overwritten ref was already processed. If yes, the ref
1898 	 * was already unlinked/moved, so we can safely assume that we will not
1899 	 * overwrite anything at this point in time.
1900 	 */
1901 	if (other_inode > sctx->send_progress ||
1902 	    is_waiting_for_move(sctx, other_inode)) {
1903 		ret = get_inode_info(sctx->parent_root, other_inode, NULL,
1904 				who_gen, who_mode, NULL, NULL, NULL);
1905 		if (ret < 0)
1906 			goto out;
1907 
1908 		ret = 1;
1909 		*who_ino = other_inode;
1910 	} else {
1911 		ret = 0;
1912 	}
1913 
1914 out:
1915 	return ret;
1916 }
1917 
1918 /*
1919  * Checks if the ref was overwritten by an already processed inode. This is
1920  * used by __get_cur_name_and_parent to find out if the ref was orphanized and
1921  * thus the orphan name needs be used.
1922  * process_recorded_refs also uses it to avoid unlinking of refs that were
1923  * overwritten.
1924  */
did_overwrite_ref(struct send_ctx * sctx,u64 dir,u64 dir_gen,u64 ino,u64 ino_gen,const char * name,int name_len)1925 static int did_overwrite_ref(struct send_ctx *sctx,
1926 			    u64 dir, u64 dir_gen,
1927 			    u64 ino, u64 ino_gen,
1928 			    const char *name, int name_len)
1929 {
1930 	int ret = 0;
1931 	u64 gen;
1932 	u64 ow_inode;
1933 	u8 other_type;
1934 
1935 	if (!sctx->parent_root)
1936 		goto out;
1937 
1938 	ret = is_inode_existent(sctx, dir, dir_gen);
1939 	if (ret <= 0)
1940 		goto out;
1941 
1942 	if (dir != BTRFS_FIRST_FREE_OBJECTID) {
1943 		ret = get_inode_info(sctx->send_root, dir, NULL, &gen, NULL,
1944 				     NULL, NULL, NULL);
1945 		if (ret < 0 && ret != -ENOENT)
1946 			goto out;
1947 		if (ret) {
1948 			ret = 0;
1949 			goto out;
1950 		}
1951 		if (gen != dir_gen)
1952 			goto out;
1953 	}
1954 
1955 	/* check if the ref was overwritten by another ref */
1956 	ret = lookup_dir_item_inode(sctx->send_root, dir, name, name_len,
1957 			&ow_inode, &other_type);
1958 	if (ret < 0 && ret != -ENOENT)
1959 		goto out;
1960 	if (ret) {
1961 		/* was never and will never be overwritten */
1962 		ret = 0;
1963 		goto out;
1964 	}
1965 
1966 	ret = get_inode_info(sctx->send_root, ow_inode, NULL, &gen, NULL, NULL,
1967 			NULL, NULL);
1968 	if (ret < 0)
1969 		goto out;
1970 
1971 	if (ow_inode == ino && gen == ino_gen) {
1972 		ret = 0;
1973 		goto out;
1974 	}
1975 
1976 	/*
1977 	 * We know that it is or will be overwritten. Check this now.
1978 	 * The current inode being processed might have been the one that caused
1979 	 * inode 'ino' to be orphanized, therefore check if ow_inode matches
1980 	 * the current inode being processed.
1981 	 */
1982 	if ((ow_inode < sctx->send_progress) ||
1983 	    (ino != sctx->cur_ino && ow_inode == sctx->cur_ino &&
1984 	     gen == sctx->cur_inode_gen))
1985 		ret = 1;
1986 	else
1987 		ret = 0;
1988 
1989 out:
1990 	return ret;
1991 }
1992 
1993 /*
1994  * Same as did_overwrite_ref, but also checks if it is the first ref of an inode
1995  * that got overwritten. This is used by process_recorded_refs to determine
1996  * if it has to use the path as returned by get_cur_path or the orphan name.
1997  */
did_overwrite_first_ref(struct send_ctx * sctx,u64 ino,u64 gen)1998 static int did_overwrite_first_ref(struct send_ctx *sctx, u64 ino, u64 gen)
1999 {
2000 	int ret = 0;
2001 	struct fs_path *name = NULL;
2002 	u64 dir;
2003 	u64 dir_gen;
2004 
2005 	if (!sctx->parent_root)
2006 		goto out;
2007 
2008 	name = fs_path_alloc();
2009 	if (!name)
2010 		return -ENOMEM;
2011 
2012 	ret = get_first_ref(sctx->parent_root, ino, &dir, &dir_gen, name);
2013 	if (ret < 0)
2014 		goto out;
2015 
2016 	ret = did_overwrite_ref(sctx, dir, dir_gen, ino, gen,
2017 			name->start, fs_path_len(name));
2018 
2019 out:
2020 	fs_path_free(name);
2021 	return ret;
2022 }
2023 
2024 /*
2025  * Insert a name cache entry. On 32bit kernels the radix tree index is 32bit,
2026  * so we need to do some special handling in case we have clashes. This function
2027  * takes care of this with the help of name_cache_entry::radix_list.
2028  * In case of error, nce is kfreed.
2029  */
name_cache_insert(struct send_ctx * sctx,struct name_cache_entry * nce)2030 static int name_cache_insert(struct send_ctx *sctx,
2031 			     struct name_cache_entry *nce)
2032 {
2033 	int ret = 0;
2034 	struct list_head *nce_head;
2035 
2036 	nce_head = radix_tree_lookup(&sctx->name_cache,
2037 			(unsigned long)nce->ino);
2038 	if (!nce_head) {
2039 		nce_head = kmalloc(sizeof(*nce_head), GFP_KERNEL);
2040 		if (!nce_head) {
2041 			kfree(nce);
2042 			return -ENOMEM;
2043 		}
2044 		INIT_LIST_HEAD(nce_head);
2045 
2046 		ret = radix_tree_insert(&sctx->name_cache, nce->ino, nce_head);
2047 		if (ret < 0) {
2048 			kfree(nce_head);
2049 			kfree(nce);
2050 			return ret;
2051 		}
2052 	}
2053 	list_add_tail(&nce->radix_list, nce_head);
2054 	list_add_tail(&nce->list, &sctx->name_cache_list);
2055 	sctx->name_cache_size++;
2056 
2057 	return ret;
2058 }
2059 
name_cache_delete(struct send_ctx * sctx,struct name_cache_entry * nce)2060 static void name_cache_delete(struct send_ctx *sctx,
2061 			      struct name_cache_entry *nce)
2062 {
2063 	struct list_head *nce_head;
2064 
2065 	nce_head = radix_tree_lookup(&sctx->name_cache,
2066 			(unsigned long)nce->ino);
2067 	if (!nce_head) {
2068 		btrfs_err(sctx->send_root->fs_info,
2069 	      "name_cache_delete lookup failed ino %llu cache size %d, leaking memory",
2070 			nce->ino, sctx->name_cache_size);
2071 	}
2072 
2073 	list_del(&nce->radix_list);
2074 	list_del(&nce->list);
2075 	sctx->name_cache_size--;
2076 
2077 	/*
2078 	 * We may not get to the final release of nce_head if the lookup fails
2079 	 */
2080 	if (nce_head && list_empty(nce_head)) {
2081 		radix_tree_delete(&sctx->name_cache, (unsigned long)nce->ino);
2082 		kfree(nce_head);
2083 	}
2084 }
2085 
name_cache_search(struct send_ctx * sctx,u64 ino,u64 gen)2086 static struct name_cache_entry *name_cache_search(struct send_ctx *sctx,
2087 						    u64 ino, u64 gen)
2088 {
2089 	struct list_head *nce_head;
2090 	struct name_cache_entry *cur;
2091 
2092 	nce_head = radix_tree_lookup(&sctx->name_cache, (unsigned long)ino);
2093 	if (!nce_head)
2094 		return NULL;
2095 
2096 	list_for_each_entry(cur, nce_head, radix_list) {
2097 		if (cur->ino == ino && cur->gen == gen)
2098 			return cur;
2099 	}
2100 	return NULL;
2101 }
2102 
2103 /*
2104  * Remove some entries from the beginning of name_cache_list.
2105  */
name_cache_clean_unused(struct send_ctx * sctx)2106 static void name_cache_clean_unused(struct send_ctx *sctx)
2107 {
2108 	struct name_cache_entry *nce;
2109 
2110 	if (sctx->name_cache_size < SEND_CTX_NAME_CACHE_CLEAN_SIZE)
2111 		return;
2112 
2113 	while (sctx->name_cache_size > SEND_CTX_MAX_NAME_CACHE_SIZE) {
2114 		nce = list_entry(sctx->name_cache_list.next,
2115 				struct name_cache_entry, list);
2116 		name_cache_delete(sctx, nce);
2117 		kfree(nce);
2118 	}
2119 }
2120 
name_cache_free(struct send_ctx * sctx)2121 static void name_cache_free(struct send_ctx *sctx)
2122 {
2123 	struct name_cache_entry *nce;
2124 
2125 	while (!list_empty(&sctx->name_cache_list)) {
2126 		nce = list_entry(sctx->name_cache_list.next,
2127 				struct name_cache_entry, list);
2128 		name_cache_delete(sctx, nce);
2129 		kfree(nce);
2130 	}
2131 }
2132 
2133 /*
2134  * Used by get_cur_path for each ref up to the root.
2135  * Returns 0 if it succeeded.
2136  * Returns 1 if the inode is not existent or got overwritten. In that case, the
2137  * name is an orphan name. This instructs get_cur_path to stop iterating. If 1
2138  * is returned, parent_ino/parent_gen are not guaranteed to be valid.
2139  * Returns <0 in case of error.
2140  */
__get_cur_name_and_parent(struct send_ctx * sctx,u64 ino,u64 gen,u64 * parent_ino,u64 * parent_gen,struct fs_path * dest)2141 static int __get_cur_name_and_parent(struct send_ctx *sctx,
2142 				     u64 ino, u64 gen,
2143 				     u64 *parent_ino,
2144 				     u64 *parent_gen,
2145 				     struct fs_path *dest)
2146 {
2147 	int ret;
2148 	int nce_ret;
2149 	struct name_cache_entry *nce = NULL;
2150 
2151 	/*
2152 	 * First check if we already did a call to this function with the same
2153 	 * ino/gen. If yes, check if the cache entry is still up-to-date. If yes
2154 	 * return the cached result.
2155 	 */
2156 	nce = name_cache_search(sctx, ino, gen);
2157 	if (nce) {
2158 		if (ino < sctx->send_progress && nce->need_later_update) {
2159 			name_cache_delete(sctx, nce);
2160 			kfree(nce);
2161 			nce = NULL;
2162 		} else {
2163 			/*
2164 			 * Removes the entry from the list and adds it back to
2165 			 * the end.  This marks the entry as recently used so
2166 			 * that name_cache_clean_unused does not remove it.
2167 			 */
2168 			list_move_tail(&nce->list, &sctx->name_cache_list);
2169 
2170 			*parent_ino = nce->parent_ino;
2171 			*parent_gen = nce->parent_gen;
2172 			ret = fs_path_add(dest, nce->name, nce->name_len);
2173 			if (ret < 0)
2174 				goto out;
2175 			ret = nce->ret;
2176 			goto out;
2177 		}
2178 	}
2179 
2180 	/*
2181 	 * If the inode is not existent yet, add the orphan name and return 1.
2182 	 * This should only happen for the parent dir that we determine in
2183 	 * __record_new_ref
2184 	 */
2185 	ret = is_inode_existent(sctx, ino, gen);
2186 	if (ret < 0)
2187 		goto out;
2188 
2189 	if (!ret) {
2190 		ret = gen_unique_name(sctx, ino, gen, dest);
2191 		if (ret < 0)
2192 			goto out;
2193 		ret = 1;
2194 		goto out_cache;
2195 	}
2196 
2197 	/*
2198 	 * Depending on whether the inode was already processed or not, use
2199 	 * send_root or parent_root for ref lookup.
2200 	 */
2201 	if (ino < sctx->send_progress)
2202 		ret = get_first_ref(sctx->send_root, ino,
2203 				    parent_ino, parent_gen, dest);
2204 	else
2205 		ret = get_first_ref(sctx->parent_root, ino,
2206 				    parent_ino, parent_gen, dest);
2207 	if (ret < 0)
2208 		goto out;
2209 
2210 	/*
2211 	 * Check if the ref was overwritten by an inode's ref that was processed
2212 	 * earlier. If yes, treat as orphan and return 1.
2213 	 */
2214 	ret = did_overwrite_ref(sctx, *parent_ino, *parent_gen, ino, gen,
2215 			dest->start, dest->end - dest->start);
2216 	if (ret < 0)
2217 		goto out;
2218 	if (ret) {
2219 		fs_path_reset(dest);
2220 		ret = gen_unique_name(sctx, ino, gen, dest);
2221 		if (ret < 0)
2222 			goto out;
2223 		ret = 1;
2224 	}
2225 
2226 out_cache:
2227 	/*
2228 	 * Store the result of the lookup in the name cache.
2229 	 */
2230 	nce = kmalloc(sizeof(*nce) + fs_path_len(dest) + 1, GFP_KERNEL);
2231 	if (!nce) {
2232 		ret = -ENOMEM;
2233 		goto out;
2234 	}
2235 
2236 	nce->ino = ino;
2237 	nce->gen = gen;
2238 	nce->parent_ino = *parent_ino;
2239 	nce->parent_gen = *parent_gen;
2240 	nce->name_len = fs_path_len(dest);
2241 	nce->ret = ret;
2242 	strcpy(nce->name, dest->start);
2243 
2244 	if (ino < sctx->send_progress)
2245 		nce->need_later_update = 0;
2246 	else
2247 		nce->need_later_update = 1;
2248 
2249 	nce_ret = name_cache_insert(sctx, nce);
2250 	if (nce_ret < 0)
2251 		ret = nce_ret;
2252 	name_cache_clean_unused(sctx);
2253 
2254 out:
2255 	return ret;
2256 }
2257 
2258 /*
2259  * Magic happens here. This function returns the first ref to an inode as it
2260  * would look like while receiving the stream at this point in time.
2261  * We walk the path up to the root. For every inode in between, we check if it
2262  * was already processed/sent. If yes, we continue with the parent as found
2263  * in send_root. If not, we continue with the parent as found in parent_root.
2264  * If we encounter an inode that was deleted at this point in time, we use the
2265  * inodes "orphan" name instead of the real name and stop. Same with new inodes
2266  * that were not created yet and overwritten inodes/refs.
2267  *
2268  * When do we have orphan inodes:
2269  * 1. When an inode is freshly created and thus no valid refs are available yet
2270  * 2. When a directory lost all it's refs (deleted) but still has dir items
2271  *    inside which were not processed yet (pending for move/delete). If anyone
2272  *    tried to get the path to the dir items, it would get a path inside that
2273  *    orphan directory.
2274  * 3. When an inode is moved around or gets new links, it may overwrite the ref
2275  *    of an unprocessed inode. If in that case the first ref would be
2276  *    overwritten, the overwritten inode gets "orphanized". Later when we
2277  *    process this overwritten inode, it is restored at a new place by moving
2278  *    the orphan inode.
2279  *
2280  * sctx->send_progress tells this function at which point in time receiving
2281  * would be.
2282  */
get_cur_path(struct send_ctx * sctx,u64 ino,u64 gen,struct fs_path * dest)2283 static int get_cur_path(struct send_ctx *sctx, u64 ino, u64 gen,
2284 			struct fs_path *dest)
2285 {
2286 	int ret = 0;
2287 	struct fs_path *name = NULL;
2288 	u64 parent_inode = 0;
2289 	u64 parent_gen = 0;
2290 	int stop = 0;
2291 
2292 	name = fs_path_alloc();
2293 	if (!name) {
2294 		ret = -ENOMEM;
2295 		goto out;
2296 	}
2297 
2298 	dest->reversed = 1;
2299 	fs_path_reset(dest);
2300 
2301 	while (!stop && ino != BTRFS_FIRST_FREE_OBJECTID) {
2302 		struct waiting_dir_move *wdm;
2303 
2304 		fs_path_reset(name);
2305 
2306 		if (is_waiting_for_rm(sctx, ino, gen)) {
2307 			ret = gen_unique_name(sctx, ino, gen, name);
2308 			if (ret < 0)
2309 				goto out;
2310 			ret = fs_path_add_path(dest, name);
2311 			break;
2312 		}
2313 
2314 		wdm = get_waiting_dir_move(sctx, ino);
2315 		if (wdm && wdm->orphanized) {
2316 			ret = gen_unique_name(sctx, ino, gen, name);
2317 			stop = 1;
2318 		} else if (wdm) {
2319 			ret = get_first_ref(sctx->parent_root, ino,
2320 					    &parent_inode, &parent_gen, name);
2321 		} else {
2322 			ret = __get_cur_name_and_parent(sctx, ino, gen,
2323 							&parent_inode,
2324 							&parent_gen, name);
2325 			if (ret)
2326 				stop = 1;
2327 		}
2328 
2329 		if (ret < 0)
2330 			goto out;
2331 
2332 		ret = fs_path_add_path(dest, name);
2333 		if (ret < 0)
2334 			goto out;
2335 
2336 		ino = parent_inode;
2337 		gen = parent_gen;
2338 	}
2339 
2340 out:
2341 	fs_path_free(name);
2342 	if (!ret)
2343 		fs_path_unreverse(dest);
2344 	return ret;
2345 }
2346 
2347 /*
2348  * Sends a BTRFS_SEND_C_SUBVOL command/item to userspace
2349  */
send_subvol_begin(struct send_ctx * sctx)2350 static int send_subvol_begin(struct send_ctx *sctx)
2351 {
2352 	int ret;
2353 	struct btrfs_root *send_root = sctx->send_root;
2354 	struct btrfs_root *parent_root = sctx->parent_root;
2355 	struct btrfs_path *path;
2356 	struct btrfs_key key;
2357 	struct btrfs_root_ref *ref;
2358 	struct extent_buffer *leaf;
2359 	char *name = NULL;
2360 	int namelen;
2361 
2362 	path = btrfs_alloc_path();
2363 	if (!path)
2364 		return -ENOMEM;
2365 
2366 	name = kmalloc(BTRFS_PATH_NAME_MAX, GFP_KERNEL);
2367 	if (!name) {
2368 		btrfs_free_path(path);
2369 		return -ENOMEM;
2370 	}
2371 
2372 	key.objectid = send_root->root_key.objectid;
2373 	key.type = BTRFS_ROOT_BACKREF_KEY;
2374 	key.offset = 0;
2375 
2376 	ret = btrfs_search_slot_for_read(send_root->fs_info->tree_root,
2377 				&key, path, 1, 0);
2378 	if (ret < 0)
2379 		goto out;
2380 	if (ret) {
2381 		ret = -ENOENT;
2382 		goto out;
2383 	}
2384 
2385 	leaf = path->nodes[0];
2386 	btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
2387 	if (key.type != BTRFS_ROOT_BACKREF_KEY ||
2388 	    key.objectid != send_root->root_key.objectid) {
2389 		ret = -ENOENT;
2390 		goto out;
2391 	}
2392 	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
2393 	namelen = btrfs_root_ref_name_len(leaf, ref);
2394 	read_extent_buffer(leaf, name, (unsigned long)(ref + 1), namelen);
2395 	btrfs_release_path(path);
2396 
2397 	if (parent_root) {
2398 		ret = begin_cmd(sctx, BTRFS_SEND_C_SNAPSHOT);
2399 		if (ret < 0)
2400 			goto out;
2401 	} else {
2402 		ret = begin_cmd(sctx, BTRFS_SEND_C_SUBVOL);
2403 		if (ret < 0)
2404 			goto out;
2405 	}
2406 
2407 	TLV_PUT_STRING(sctx, BTRFS_SEND_A_PATH, name, namelen);
2408 
2409 	if (!btrfs_is_empty_uuid(sctx->send_root->root_item.received_uuid))
2410 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
2411 			    sctx->send_root->root_item.received_uuid);
2412 	else
2413 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_UUID,
2414 			    sctx->send_root->root_item.uuid);
2415 
2416 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CTRANSID,
2417 		    btrfs_root_ctransid(&sctx->send_root->root_item));
2418 	if (parent_root) {
2419 		if (!btrfs_is_empty_uuid(parent_root->root_item.received_uuid))
2420 			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
2421 				     parent_root->root_item.received_uuid);
2422 		else
2423 			TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
2424 				     parent_root->root_item.uuid);
2425 		TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
2426 			    btrfs_root_ctransid(&sctx->parent_root->root_item));
2427 	}
2428 
2429 	ret = send_cmd(sctx);
2430 
2431 tlv_put_failure:
2432 out:
2433 	btrfs_free_path(path);
2434 	kfree(name);
2435 	return ret;
2436 }
2437 
send_truncate(struct send_ctx * sctx,u64 ino,u64 gen,u64 size)2438 static int send_truncate(struct send_ctx *sctx, u64 ino, u64 gen, u64 size)
2439 {
2440 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2441 	int ret = 0;
2442 	struct fs_path *p;
2443 
2444 	btrfs_debug(fs_info, "send_truncate %llu size=%llu", ino, size);
2445 
2446 	p = fs_path_alloc();
2447 	if (!p)
2448 		return -ENOMEM;
2449 
2450 	ret = begin_cmd(sctx, BTRFS_SEND_C_TRUNCATE);
2451 	if (ret < 0)
2452 		goto out;
2453 
2454 	ret = get_cur_path(sctx, ino, gen, p);
2455 	if (ret < 0)
2456 		goto out;
2457 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2458 	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, size);
2459 
2460 	ret = send_cmd(sctx);
2461 
2462 tlv_put_failure:
2463 out:
2464 	fs_path_free(p);
2465 	return ret;
2466 }
2467 
send_chmod(struct send_ctx * sctx,u64 ino,u64 gen,u64 mode)2468 static int send_chmod(struct send_ctx *sctx, u64 ino, u64 gen, u64 mode)
2469 {
2470 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2471 	int ret = 0;
2472 	struct fs_path *p;
2473 
2474 	btrfs_debug(fs_info, "send_chmod %llu mode=%llu", ino, mode);
2475 
2476 	p = fs_path_alloc();
2477 	if (!p)
2478 		return -ENOMEM;
2479 
2480 	ret = begin_cmd(sctx, BTRFS_SEND_C_CHMOD);
2481 	if (ret < 0)
2482 		goto out;
2483 
2484 	ret = get_cur_path(sctx, ino, gen, p);
2485 	if (ret < 0)
2486 		goto out;
2487 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2488 	TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode & 07777);
2489 
2490 	ret = send_cmd(sctx);
2491 
2492 tlv_put_failure:
2493 out:
2494 	fs_path_free(p);
2495 	return ret;
2496 }
2497 
send_chown(struct send_ctx * sctx,u64 ino,u64 gen,u64 uid,u64 gid)2498 static int send_chown(struct send_ctx *sctx, u64 ino, u64 gen, u64 uid, u64 gid)
2499 {
2500 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2501 	int ret = 0;
2502 	struct fs_path *p;
2503 
2504 	btrfs_debug(fs_info, "send_chown %llu uid=%llu, gid=%llu",
2505 		    ino, uid, gid);
2506 
2507 	p = fs_path_alloc();
2508 	if (!p)
2509 		return -ENOMEM;
2510 
2511 	ret = begin_cmd(sctx, BTRFS_SEND_C_CHOWN);
2512 	if (ret < 0)
2513 		goto out;
2514 
2515 	ret = get_cur_path(sctx, ino, gen, p);
2516 	if (ret < 0)
2517 		goto out;
2518 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2519 	TLV_PUT_U64(sctx, BTRFS_SEND_A_UID, uid);
2520 	TLV_PUT_U64(sctx, BTRFS_SEND_A_GID, gid);
2521 
2522 	ret = send_cmd(sctx);
2523 
2524 tlv_put_failure:
2525 out:
2526 	fs_path_free(p);
2527 	return ret;
2528 }
2529 
send_utimes(struct send_ctx * sctx,u64 ino,u64 gen)2530 static int send_utimes(struct send_ctx *sctx, u64 ino, u64 gen)
2531 {
2532 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2533 	int ret = 0;
2534 	struct fs_path *p = NULL;
2535 	struct btrfs_inode_item *ii;
2536 	struct btrfs_path *path = NULL;
2537 	struct extent_buffer *eb;
2538 	struct btrfs_key key;
2539 	int slot;
2540 
2541 	btrfs_debug(fs_info, "send_utimes %llu", ino);
2542 
2543 	p = fs_path_alloc();
2544 	if (!p)
2545 		return -ENOMEM;
2546 
2547 	path = alloc_path_for_send();
2548 	if (!path) {
2549 		ret = -ENOMEM;
2550 		goto out;
2551 	}
2552 
2553 	key.objectid = ino;
2554 	key.type = BTRFS_INODE_ITEM_KEY;
2555 	key.offset = 0;
2556 	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
2557 	if (ret > 0)
2558 		ret = -ENOENT;
2559 	if (ret < 0)
2560 		goto out;
2561 
2562 	eb = path->nodes[0];
2563 	slot = path->slots[0];
2564 	ii = btrfs_item_ptr(eb, slot, struct btrfs_inode_item);
2565 
2566 	ret = begin_cmd(sctx, BTRFS_SEND_C_UTIMES);
2567 	if (ret < 0)
2568 		goto out;
2569 
2570 	ret = get_cur_path(sctx, ino, gen, p);
2571 	if (ret < 0)
2572 		goto out;
2573 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2574 	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_ATIME, eb, &ii->atime);
2575 	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_MTIME, eb, &ii->mtime);
2576 	TLV_PUT_BTRFS_TIMESPEC(sctx, BTRFS_SEND_A_CTIME, eb, &ii->ctime);
2577 	/* TODO Add otime support when the otime patches get into upstream */
2578 
2579 	ret = send_cmd(sctx);
2580 
2581 tlv_put_failure:
2582 out:
2583 	fs_path_free(p);
2584 	btrfs_free_path(path);
2585 	return ret;
2586 }
2587 
2588 /*
2589  * Sends a BTRFS_SEND_C_MKXXX or SYMLINK command to user space. We don't have
2590  * a valid path yet because we did not process the refs yet. So, the inode
2591  * is created as orphan.
2592  */
send_create_inode(struct send_ctx * sctx,u64 ino)2593 static int send_create_inode(struct send_ctx *sctx, u64 ino)
2594 {
2595 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
2596 	int ret = 0;
2597 	struct fs_path *p;
2598 	int cmd;
2599 	u64 gen;
2600 	u64 mode;
2601 	u64 rdev;
2602 
2603 	btrfs_debug(fs_info, "send_create_inode %llu", ino);
2604 
2605 	p = fs_path_alloc();
2606 	if (!p)
2607 		return -ENOMEM;
2608 
2609 	if (ino != sctx->cur_ino) {
2610 		ret = get_inode_info(sctx->send_root, ino, NULL, &gen, &mode,
2611 				     NULL, NULL, &rdev);
2612 		if (ret < 0)
2613 			goto out;
2614 	} else {
2615 		gen = sctx->cur_inode_gen;
2616 		mode = sctx->cur_inode_mode;
2617 		rdev = sctx->cur_inode_rdev;
2618 	}
2619 
2620 	if (S_ISREG(mode)) {
2621 		cmd = BTRFS_SEND_C_MKFILE;
2622 	} else if (S_ISDIR(mode)) {
2623 		cmd = BTRFS_SEND_C_MKDIR;
2624 	} else if (S_ISLNK(mode)) {
2625 		cmd = BTRFS_SEND_C_SYMLINK;
2626 	} else if (S_ISCHR(mode) || S_ISBLK(mode)) {
2627 		cmd = BTRFS_SEND_C_MKNOD;
2628 	} else if (S_ISFIFO(mode)) {
2629 		cmd = BTRFS_SEND_C_MKFIFO;
2630 	} else if (S_ISSOCK(mode)) {
2631 		cmd = BTRFS_SEND_C_MKSOCK;
2632 	} else {
2633 		btrfs_warn(sctx->send_root->fs_info, "unexpected inode type %o",
2634 				(int)(mode & S_IFMT));
2635 		ret = -EOPNOTSUPP;
2636 		goto out;
2637 	}
2638 
2639 	ret = begin_cmd(sctx, cmd);
2640 	if (ret < 0)
2641 		goto out;
2642 
2643 	ret = gen_unique_name(sctx, ino, gen, p);
2644 	if (ret < 0)
2645 		goto out;
2646 
2647 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
2648 	TLV_PUT_U64(sctx, BTRFS_SEND_A_INO, ino);
2649 
2650 	if (S_ISLNK(mode)) {
2651 		fs_path_reset(p);
2652 		ret = read_symlink(sctx->send_root, ino, p);
2653 		if (ret < 0)
2654 			goto out;
2655 		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH_LINK, p);
2656 	} else if (S_ISCHR(mode) || S_ISBLK(mode) ||
2657 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
2658 		TLV_PUT_U64(sctx, BTRFS_SEND_A_RDEV, new_encode_dev(rdev));
2659 		TLV_PUT_U64(sctx, BTRFS_SEND_A_MODE, mode);
2660 	}
2661 
2662 	ret = send_cmd(sctx);
2663 	if (ret < 0)
2664 		goto out;
2665 
2666 
2667 tlv_put_failure:
2668 out:
2669 	fs_path_free(p);
2670 	return ret;
2671 }
2672 
2673 /*
2674  * We need some special handling for inodes that get processed before the parent
2675  * directory got created. See process_recorded_refs for details.
2676  * This function does the check if we already created the dir out of order.
2677  */
did_create_dir(struct send_ctx * sctx,u64 dir)2678 static int did_create_dir(struct send_ctx *sctx, u64 dir)
2679 {
2680 	int ret = 0;
2681 	struct btrfs_path *path = NULL;
2682 	struct btrfs_key key;
2683 	struct btrfs_key found_key;
2684 	struct btrfs_key di_key;
2685 	struct extent_buffer *eb;
2686 	struct btrfs_dir_item *di;
2687 	int slot;
2688 
2689 	path = alloc_path_for_send();
2690 	if (!path) {
2691 		ret = -ENOMEM;
2692 		goto out;
2693 	}
2694 
2695 	key.objectid = dir;
2696 	key.type = BTRFS_DIR_INDEX_KEY;
2697 	key.offset = 0;
2698 	ret = btrfs_search_slot(NULL, sctx->send_root, &key, path, 0, 0);
2699 	if (ret < 0)
2700 		goto out;
2701 
2702 	while (1) {
2703 		eb = path->nodes[0];
2704 		slot = path->slots[0];
2705 		if (slot >= btrfs_header_nritems(eb)) {
2706 			ret = btrfs_next_leaf(sctx->send_root, path);
2707 			if (ret < 0) {
2708 				goto out;
2709 			} else if (ret > 0) {
2710 				ret = 0;
2711 				break;
2712 			}
2713 			continue;
2714 		}
2715 
2716 		btrfs_item_key_to_cpu(eb, &found_key, slot);
2717 		if (found_key.objectid != key.objectid ||
2718 		    found_key.type != key.type) {
2719 			ret = 0;
2720 			goto out;
2721 		}
2722 
2723 		di = btrfs_item_ptr(eb, slot, struct btrfs_dir_item);
2724 		btrfs_dir_item_key_to_cpu(eb, di, &di_key);
2725 
2726 		if (di_key.type != BTRFS_ROOT_ITEM_KEY &&
2727 		    di_key.objectid < sctx->send_progress) {
2728 			ret = 1;
2729 			goto out;
2730 		}
2731 
2732 		path->slots[0]++;
2733 	}
2734 
2735 out:
2736 	btrfs_free_path(path);
2737 	return ret;
2738 }
2739 
2740 /*
2741  * Only creates the inode if it is:
2742  * 1. Not a directory
2743  * 2. Or a directory which was not created already due to out of order
2744  *    directories. See did_create_dir and process_recorded_refs for details.
2745  */
send_create_inode_if_needed(struct send_ctx * sctx)2746 static int send_create_inode_if_needed(struct send_ctx *sctx)
2747 {
2748 	int ret;
2749 
2750 	if (S_ISDIR(sctx->cur_inode_mode)) {
2751 		ret = did_create_dir(sctx, sctx->cur_ino);
2752 		if (ret < 0)
2753 			goto out;
2754 		if (ret) {
2755 			ret = 0;
2756 			goto out;
2757 		}
2758 	}
2759 
2760 	ret = send_create_inode(sctx, sctx->cur_ino);
2761 	if (ret < 0)
2762 		goto out;
2763 
2764 out:
2765 	return ret;
2766 }
2767 
2768 struct recorded_ref {
2769 	struct list_head list;
2770 	char *name;
2771 	struct fs_path *full_path;
2772 	u64 dir;
2773 	u64 dir_gen;
2774 	int name_len;
2775 };
2776 
set_ref_path(struct recorded_ref * ref,struct fs_path * path)2777 static void set_ref_path(struct recorded_ref *ref, struct fs_path *path)
2778 {
2779 	ref->full_path = path;
2780 	ref->name = (char *)kbasename(ref->full_path->start);
2781 	ref->name_len = ref->full_path->end - ref->name;
2782 }
2783 
2784 /*
2785  * We need to process new refs before deleted refs, but compare_tree gives us
2786  * everything mixed. So we first record all refs and later process them.
2787  * This function is a helper to record one ref.
2788  */
__record_ref(struct list_head * head,u64 dir,u64 dir_gen,struct fs_path * path)2789 static int __record_ref(struct list_head *head, u64 dir,
2790 		      u64 dir_gen, struct fs_path *path)
2791 {
2792 	struct recorded_ref *ref;
2793 
2794 	ref = kmalloc(sizeof(*ref), GFP_KERNEL);
2795 	if (!ref)
2796 		return -ENOMEM;
2797 
2798 	ref->dir = dir;
2799 	ref->dir_gen = dir_gen;
2800 	set_ref_path(ref, path);
2801 	list_add_tail(&ref->list, head);
2802 	return 0;
2803 }
2804 
dup_ref(struct recorded_ref * ref,struct list_head * list)2805 static int dup_ref(struct recorded_ref *ref, struct list_head *list)
2806 {
2807 	struct recorded_ref *new;
2808 
2809 	new = kmalloc(sizeof(*ref), GFP_KERNEL);
2810 	if (!new)
2811 		return -ENOMEM;
2812 
2813 	new->dir = ref->dir;
2814 	new->dir_gen = ref->dir_gen;
2815 	new->full_path = NULL;
2816 	INIT_LIST_HEAD(&new->list);
2817 	list_add_tail(&new->list, list);
2818 	return 0;
2819 }
2820 
__free_recorded_refs(struct list_head * head)2821 static void __free_recorded_refs(struct list_head *head)
2822 {
2823 	struct recorded_ref *cur;
2824 
2825 	while (!list_empty(head)) {
2826 		cur = list_entry(head->next, struct recorded_ref, list);
2827 		fs_path_free(cur->full_path);
2828 		list_del(&cur->list);
2829 		kfree(cur);
2830 	}
2831 }
2832 
free_recorded_refs(struct send_ctx * sctx)2833 static void free_recorded_refs(struct send_ctx *sctx)
2834 {
2835 	__free_recorded_refs(&sctx->new_refs);
2836 	__free_recorded_refs(&sctx->deleted_refs);
2837 }
2838 
2839 /*
2840  * Renames/moves a file/dir to its orphan name. Used when the first
2841  * ref of an unprocessed inode gets overwritten and for all non empty
2842  * directories.
2843  */
orphanize_inode(struct send_ctx * sctx,u64 ino,u64 gen,struct fs_path * path)2844 static int orphanize_inode(struct send_ctx *sctx, u64 ino, u64 gen,
2845 			  struct fs_path *path)
2846 {
2847 	int ret;
2848 	struct fs_path *orphan;
2849 
2850 	orphan = fs_path_alloc();
2851 	if (!orphan)
2852 		return -ENOMEM;
2853 
2854 	ret = gen_unique_name(sctx, ino, gen, orphan);
2855 	if (ret < 0)
2856 		goto out;
2857 
2858 	ret = send_rename(sctx, path, orphan);
2859 
2860 out:
2861 	fs_path_free(orphan);
2862 	return ret;
2863 }
2864 
add_orphan_dir_info(struct send_ctx * sctx,u64 dir_ino,u64 dir_gen)2865 static struct orphan_dir_info *add_orphan_dir_info(struct send_ctx *sctx,
2866 						   u64 dir_ino, u64 dir_gen)
2867 {
2868 	struct rb_node **p = &sctx->orphan_dirs.rb_node;
2869 	struct rb_node *parent = NULL;
2870 	struct orphan_dir_info *entry, *odi;
2871 
2872 	while (*p) {
2873 		parent = *p;
2874 		entry = rb_entry(parent, struct orphan_dir_info, node);
2875 		if (dir_ino < entry->ino)
2876 			p = &(*p)->rb_left;
2877 		else if (dir_ino > entry->ino)
2878 			p = &(*p)->rb_right;
2879 		else if (dir_gen < entry->gen)
2880 			p = &(*p)->rb_left;
2881 		else if (dir_gen > entry->gen)
2882 			p = &(*p)->rb_right;
2883 		else
2884 			return entry;
2885 	}
2886 
2887 	odi = kmalloc(sizeof(*odi), GFP_KERNEL);
2888 	if (!odi)
2889 		return ERR_PTR(-ENOMEM);
2890 	odi->ino = dir_ino;
2891 	odi->gen = dir_gen;
2892 	odi->last_dir_index_offset = 0;
2893 
2894 	rb_link_node(&odi->node, parent, p);
2895 	rb_insert_color(&odi->node, &sctx->orphan_dirs);
2896 	return odi;
2897 }
2898 
get_orphan_dir_info(struct send_ctx * sctx,u64 dir_ino,u64 gen)2899 static struct orphan_dir_info *get_orphan_dir_info(struct send_ctx *sctx,
2900 						   u64 dir_ino, u64 gen)
2901 {
2902 	struct rb_node *n = sctx->orphan_dirs.rb_node;
2903 	struct orphan_dir_info *entry;
2904 
2905 	while (n) {
2906 		entry = rb_entry(n, struct orphan_dir_info, node);
2907 		if (dir_ino < entry->ino)
2908 			n = n->rb_left;
2909 		else if (dir_ino > entry->ino)
2910 			n = n->rb_right;
2911 		else if (gen < entry->gen)
2912 			n = n->rb_left;
2913 		else if (gen > entry->gen)
2914 			n = n->rb_right;
2915 		else
2916 			return entry;
2917 	}
2918 	return NULL;
2919 }
2920 
is_waiting_for_rm(struct send_ctx * sctx,u64 dir_ino,u64 gen)2921 static int is_waiting_for_rm(struct send_ctx *sctx, u64 dir_ino, u64 gen)
2922 {
2923 	struct orphan_dir_info *odi = get_orphan_dir_info(sctx, dir_ino, gen);
2924 
2925 	return odi != NULL;
2926 }
2927 
free_orphan_dir_info(struct send_ctx * sctx,struct orphan_dir_info * odi)2928 static void free_orphan_dir_info(struct send_ctx *sctx,
2929 				 struct orphan_dir_info *odi)
2930 {
2931 	if (!odi)
2932 		return;
2933 	rb_erase(&odi->node, &sctx->orphan_dirs);
2934 	kfree(odi);
2935 }
2936 
2937 /*
2938  * Returns 1 if a directory can be removed at this point in time.
2939  * We check this by iterating all dir items and checking if the inode behind
2940  * the dir item was already processed.
2941  */
can_rmdir(struct send_ctx * sctx,u64 dir,u64 dir_gen,u64 send_progress)2942 static int can_rmdir(struct send_ctx *sctx, u64 dir, u64 dir_gen,
2943 		     u64 send_progress)
2944 {
2945 	int ret = 0;
2946 	struct btrfs_root *root = sctx->parent_root;
2947 	struct btrfs_path *path;
2948 	struct btrfs_key key;
2949 	struct btrfs_key found_key;
2950 	struct btrfs_key loc;
2951 	struct btrfs_dir_item *di;
2952 	struct orphan_dir_info *odi = NULL;
2953 
2954 	/*
2955 	 * Don't try to rmdir the top/root subvolume dir.
2956 	 */
2957 	if (dir == BTRFS_FIRST_FREE_OBJECTID)
2958 		return 0;
2959 
2960 	path = alloc_path_for_send();
2961 	if (!path)
2962 		return -ENOMEM;
2963 
2964 	key.objectid = dir;
2965 	key.type = BTRFS_DIR_INDEX_KEY;
2966 	key.offset = 0;
2967 
2968 	odi = get_orphan_dir_info(sctx, dir, dir_gen);
2969 	if (odi)
2970 		key.offset = odi->last_dir_index_offset;
2971 
2972 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
2973 	if (ret < 0)
2974 		goto out;
2975 
2976 	while (1) {
2977 		struct waiting_dir_move *dm;
2978 
2979 		if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
2980 			ret = btrfs_next_leaf(root, path);
2981 			if (ret < 0)
2982 				goto out;
2983 			else if (ret > 0)
2984 				break;
2985 			continue;
2986 		}
2987 		btrfs_item_key_to_cpu(path->nodes[0], &found_key,
2988 				      path->slots[0]);
2989 		if (found_key.objectid != key.objectid ||
2990 		    found_key.type != key.type)
2991 			break;
2992 
2993 		di = btrfs_item_ptr(path->nodes[0], path->slots[0],
2994 				struct btrfs_dir_item);
2995 		btrfs_dir_item_key_to_cpu(path->nodes[0], di, &loc);
2996 
2997 		dm = get_waiting_dir_move(sctx, loc.objectid);
2998 		if (dm) {
2999 			odi = add_orphan_dir_info(sctx, dir, dir_gen);
3000 			if (IS_ERR(odi)) {
3001 				ret = PTR_ERR(odi);
3002 				goto out;
3003 			}
3004 			odi->gen = dir_gen;
3005 			odi->last_dir_index_offset = found_key.offset;
3006 			dm->rmdir_ino = dir;
3007 			dm->rmdir_gen = dir_gen;
3008 			ret = 0;
3009 			goto out;
3010 		}
3011 
3012 		if (loc.objectid > send_progress) {
3013 			odi = add_orphan_dir_info(sctx, dir, dir_gen);
3014 			if (IS_ERR(odi)) {
3015 				ret = PTR_ERR(odi);
3016 				goto out;
3017 			}
3018 			odi->gen = dir_gen;
3019 			odi->last_dir_index_offset = found_key.offset;
3020 			ret = 0;
3021 			goto out;
3022 		}
3023 
3024 		path->slots[0]++;
3025 	}
3026 	free_orphan_dir_info(sctx, odi);
3027 
3028 	ret = 1;
3029 
3030 out:
3031 	btrfs_free_path(path);
3032 	return ret;
3033 }
3034 
is_waiting_for_move(struct send_ctx * sctx,u64 ino)3035 static int is_waiting_for_move(struct send_ctx *sctx, u64 ino)
3036 {
3037 	struct waiting_dir_move *entry = get_waiting_dir_move(sctx, ino);
3038 
3039 	return entry != NULL;
3040 }
3041 
add_waiting_dir_move(struct send_ctx * sctx,u64 ino,bool orphanized)3042 static int add_waiting_dir_move(struct send_ctx *sctx, u64 ino, bool orphanized)
3043 {
3044 	struct rb_node **p = &sctx->waiting_dir_moves.rb_node;
3045 	struct rb_node *parent = NULL;
3046 	struct waiting_dir_move *entry, *dm;
3047 
3048 	dm = kmalloc(sizeof(*dm), GFP_KERNEL);
3049 	if (!dm)
3050 		return -ENOMEM;
3051 	dm->ino = ino;
3052 	dm->rmdir_ino = 0;
3053 	dm->rmdir_gen = 0;
3054 	dm->orphanized = orphanized;
3055 
3056 	while (*p) {
3057 		parent = *p;
3058 		entry = rb_entry(parent, struct waiting_dir_move, node);
3059 		if (ino < entry->ino) {
3060 			p = &(*p)->rb_left;
3061 		} else if (ino > entry->ino) {
3062 			p = &(*p)->rb_right;
3063 		} else {
3064 			kfree(dm);
3065 			return -EEXIST;
3066 		}
3067 	}
3068 
3069 	rb_link_node(&dm->node, parent, p);
3070 	rb_insert_color(&dm->node, &sctx->waiting_dir_moves);
3071 	return 0;
3072 }
3073 
3074 static struct waiting_dir_move *
get_waiting_dir_move(struct send_ctx * sctx,u64 ino)3075 get_waiting_dir_move(struct send_ctx *sctx, u64 ino)
3076 {
3077 	struct rb_node *n = sctx->waiting_dir_moves.rb_node;
3078 	struct waiting_dir_move *entry;
3079 
3080 	while (n) {
3081 		entry = rb_entry(n, struct waiting_dir_move, node);
3082 		if (ino < entry->ino)
3083 			n = n->rb_left;
3084 		else if (ino > entry->ino)
3085 			n = n->rb_right;
3086 		else
3087 			return entry;
3088 	}
3089 	return NULL;
3090 }
3091 
free_waiting_dir_move(struct send_ctx * sctx,struct waiting_dir_move * dm)3092 static void free_waiting_dir_move(struct send_ctx *sctx,
3093 				  struct waiting_dir_move *dm)
3094 {
3095 	if (!dm)
3096 		return;
3097 	rb_erase(&dm->node, &sctx->waiting_dir_moves);
3098 	kfree(dm);
3099 }
3100 
add_pending_dir_move(struct send_ctx * sctx,u64 ino,u64 ino_gen,u64 parent_ino,struct list_head * new_refs,struct list_head * deleted_refs,const bool is_orphan)3101 static int add_pending_dir_move(struct send_ctx *sctx,
3102 				u64 ino,
3103 				u64 ino_gen,
3104 				u64 parent_ino,
3105 				struct list_head *new_refs,
3106 				struct list_head *deleted_refs,
3107 				const bool is_orphan)
3108 {
3109 	struct rb_node **p = &sctx->pending_dir_moves.rb_node;
3110 	struct rb_node *parent = NULL;
3111 	struct pending_dir_move *entry = NULL, *pm;
3112 	struct recorded_ref *cur;
3113 	int exists = 0;
3114 	int ret;
3115 
3116 	pm = kmalloc(sizeof(*pm), GFP_KERNEL);
3117 	if (!pm)
3118 		return -ENOMEM;
3119 	pm->parent_ino = parent_ino;
3120 	pm->ino = ino;
3121 	pm->gen = ino_gen;
3122 	INIT_LIST_HEAD(&pm->list);
3123 	INIT_LIST_HEAD(&pm->update_refs);
3124 	RB_CLEAR_NODE(&pm->node);
3125 
3126 	while (*p) {
3127 		parent = *p;
3128 		entry = rb_entry(parent, struct pending_dir_move, node);
3129 		if (parent_ino < entry->parent_ino) {
3130 			p = &(*p)->rb_left;
3131 		} else if (parent_ino > entry->parent_ino) {
3132 			p = &(*p)->rb_right;
3133 		} else {
3134 			exists = 1;
3135 			break;
3136 		}
3137 	}
3138 
3139 	list_for_each_entry(cur, deleted_refs, list) {
3140 		ret = dup_ref(cur, &pm->update_refs);
3141 		if (ret < 0)
3142 			goto out;
3143 	}
3144 	list_for_each_entry(cur, new_refs, list) {
3145 		ret = dup_ref(cur, &pm->update_refs);
3146 		if (ret < 0)
3147 			goto out;
3148 	}
3149 
3150 	ret = add_waiting_dir_move(sctx, pm->ino, is_orphan);
3151 	if (ret)
3152 		goto out;
3153 
3154 	if (exists) {
3155 		list_add_tail(&pm->list, &entry->list);
3156 	} else {
3157 		rb_link_node(&pm->node, parent, p);
3158 		rb_insert_color(&pm->node, &sctx->pending_dir_moves);
3159 	}
3160 	ret = 0;
3161 out:
3162 	if (ret) {
3163 		__free_recorded_refs(&pm->update_refs);
3164 		kfree(pm);
3165 	}
3166 	return ret;
3167 }
3168 
get_pending_dir_moves(struct send_ctx * sctx,u64 parent_ino)3169 static struct pending_dir_move *get_pending_dir_moves(struct send_ctx *sctx,
3170 						      u64 parent_ino)
3171 {
3172 	struct rb_node *n = sctx->pending_dir_moves.rb_node;
3173 	struct pending_dir_move *entry;
3174 
3175 	while (n) {
3176 		entry = rb_entry(n, struct pending_dir_move, node);
3177 		if (parent_ino < entry->parent_ino)
3178 			n = n->rb_left;
3179 		else if (parent_ino > entry->parent_ino)
3180 			n = n->rb_right;
3181 		else
3182 			return entry;
3183 	}
3184 	return NULL;
3185 }
3186 
path_loop(struct send_ctx * sctx,struct fs_path * name,u64 ino,u64 gen,u64 * ancestor_ino)3187 static int path_loop(struct send_ctx *sctx, struct fs_path *name,
3188 		     u64 ino, u64 gen, u64 *ancestor_ino)
3189 {
3190 	int ret = 0;
3191 	u64 parent_inode = 0;
3192 	u64 parent_gen = 0;
3193 	u64 start_ino = ino;
3194 
3195 	*ancestor_ino = 0;
3196 	while (ino != BTRFS_FIRST_FREE_OBJECTID) {
3197 		fs_path_reset(name);
3198 
3199 		if (is_waiting_for_rm(sctx, ino, gen))
3200 			break;
3201 		if (is_waiting_for_move(sctx, ino)) {
3202 			if (*ancestor_ino == 0)
3203 				*ancestor_ino = ino;
3204 			ret = get_first_ref(sctx->parent_root, ino,
3205 					    &parent_inode, &parent_gen, name);
3206 		} else {
3207 			ret = __get_cur_name_and_parent(sctx, ino, gen,
3208 							&parent_inode,
3209 							&parent_gen, name);
3210 			if (ret > 0) {
3211 				ret = 0;
3212 				break;
3213 			}
3214 		}
3215 		if (ret < 0)
3216 			break;
3217 		if (parent_inode == start_ino) {
3218 			ret = 1;
3219 			if (*ancestor_ino == 0)
3220 				*ancestor_ino = ino;
3221 			break;
3222 		}
3223 		ino = parent_inode;
3224 		gen = parent_gen;
3225 	}
3226 	return ret;
3227 }
3228 
apply_dir_move(struct send_ctx * sctx,struct pending_dir_move * pm)3229 static int apply_dir_move(struct send_ctx *sctx, struct pending_dir_move *pm)
3230 {
3231 	struct fs_path *from_path = NULL;
3232 	struct fs_path *to_path = NULL;
3233 	struct fs_path *name = NULL;
3234 	u64 orig_progress = sctx->send_progress;
3235 	struct recorded_ref *cur;
3236 	u64 parent_ino, parent_gen;
3237 	struct waiting_dir_move *dm = NULL;
3238 	u64 rmdir_ino = 0;
3239 	u64 rmdir_gen;
3240 	u64 ancestor;
3241 	bool is_orphan;
3242 	int ret;
3243 
3244 	name = fs_path_alloc();
3245 	from_path = fs_path_alloc();
3246 	if (!name || !from_path) {
3247 		ret = -ENOMEM;
3248 		goto out;
3249 	}
3250 
3251 	dm = get_waiting_dir_move(sctx, pm->ino);
3252 	ASSERT(dm);
3253 	rmdir_ino = dm->rmdir_ino;
3254 	rmdir_gen = dm->rmdir_gen;
3255 	is_orphan = dm->orphanized;
3256 	free_waiting_dir_move(sctx, dm);
3257 
3258 	if (is_orphan) {
3259 		ret = gen_unique_name(sctx, pm->ino,
3260 				      pm->gen, from_path);
3261 	} else {
3262 		ret = get_first_ref(sctx->parent_root, pm->ino,
3263 				    &parent_ino, &parent_gen, name);
3264 		if (ret < 0)
3265 			goto out;
3266 		ret = get_cur_path(sctx, parent_ino, parent_gen,
3267 				   from_path);
3268 		if (ret < 0)
3269 			goto out;
3270 		ret = fs_path_add_path(from_path, name);
3271 	}
3272 	if (ret < 0)
3273 		goto out;
3274 
3275 	sctx->send_progress = sctx->cur_ino + 1;
3276 	ret = path_loop(sctx, name, pm->ino, pm->gen, &ancestor);
3277 	if (ret < 0)
3278 		goto out;
3279 	if (ret) {
3280 		LIST_HEAD(deleted_refs);
3281 		ASSERT(ancestor > BTRFS_FIRST_FREE_OBJECTID);
3282 		ret = add_pending_dir_move(sctx, pm->ino, pm->gen, ancestor,
3283 					   &pm->update_refs, &deleted_refs,
3284 					   is_orphan);
3285 		if (ret < 0)
3286 			goto out;
3287 		if (rmdir_ino) {
3288 			dm = get_waiting_dir_move(sctx, pm->ino);
3289 			ASSERT(dm);
3290 			dm->rmdir_ino = rmdir_ino;
3291 			dm->rmdir_gen = rmdir_gen;
3292 		}
3293 		goto out;
3294 	}
3295 	fs_path_reset(name);
3296 	to_path = name;
3297 	name = NULL;
3298 	ret = get_cur_path(sctx, pm->ino, pm->gen, to_path);
3299 	if (ret < 0)
3300 		goto out;
3301 
3302 	ret = send_rename(sctx, from_path, to_path);
3303 	if (ret < 0)
3304 		goto out;
3305 
3306 	if (rmdir_ino) {
3307 		struct orphan_dir_info *odi;
3308 		u64 gen;
3309 
3310 		odi = get_orphan_dir_info(sctx, rmdir_ino, rmdir_gen);
3311 		if (!odi) {
3312 			/* already deleted */
3313 			goto finish;
3314 		}
3315 		gen = odi->gen;
3316 
3317 		ret = can_rmdir(sctx, rmdir_ino, gen, sctx->cur_ino);
3318 		if (ret < 0)
3319 			goto out;
3320 		if (!ret)
3321 			goto finish;
3322 
3323 		name = fs_path_alloc();
3324 		if (!name) {
3325 			ret = -ENOMEM;
3326 			goto out;
3327 		}
3328 		ret = get_cur_path(sctx, rmdir_ino, gen, name);
3329 		if (ret < 0)
3330 			goto out;
3331 		ret = send_rmdir(sctx, name);
3332 		if (ret < 0)
3333 			goto out;
3334 	}
3335 
3336 finish:
3337 	ret = send_utimes(sctx, pm->ino, pm->gen);
3338 	if (ret < 0)
3339 		goto out;
3340 
3341 	/*
3342 	 * After rename/move, need to update the utimes of both new parent(s)
3343 	 * and old parent(s).
3344 	 */
3345 	list_for_each_entry(cur, &pm->update_refs, list) {
3346 		/*
3347 		 * The parent inode might have been deleted in the send snapshot
3348 		 */
3349 		ret = get_inode_info(sctx->send_root, cur->dir, NULL,
3350 				     NULL, NULL, NULL, NULL, NULL);
3351 		if (ret == -ENOENT) {
3352 			ret = 0;
3353 			continue;
3354 		}
3355 		if (ret < 0)
3356 			goto out;
3357 
3358 		ret = send_utimes(sctx, cur->dir, cur->dir_gen);
3359 		if (ret < 0)
3360 			goto out;
3361 	}
3362 
3363 out:
3364 	fs_path_free(name);
3365 	fs_path_free(from_path);
3366 	fs_path_free(to_path);
3367 	sctx->send_progress = orig_progress;
3368 
3369 	return ret;
3370 }
3371 
free_pending_move(struct send_ctx * sctx,struct pending_dir_move * m)3372 static void free_pending_move(struct send_ctx *sctx, struct pending_dir_move *m)
3373 {
3374 	if (!list_empty(&m->list))
3375 		list_del(&m->list);
3376 	if (!RB_EMPTY_NODE(&m->node))
3377 		rb_erase(&m->node, &sctx->pending_dir_moves);
3378 	__free_recorded_refs(&m->update_refs);
3379 	kfree(m);
3380 }
3381 
tail_append_pending_moves(struct send_ctx * sctx,struct pending_dir_move * moves,struct list_head * stack)3382 static void tail_append_pending_moves(struct send_ctx *sctx,
3383 				      struct pending_dir_move *moves,
3384 				      struct list_head *stack)
3385 {
3386 	if (list_empty(&moves->list)) {
3387 		list_add_tail(&moves->list, stack);
3388 	} else {
3389 		LIST_HEAD(list);
3390 		list_splice_init(&moves->list, &list);
3391 		list_add_tail(&moves->list, stack);
3392 		list_splice_tail(&list, stack);
3393 	}
3394 	if (!RB_EMPTY_NODE(&moves->node)) {
3395 		rb_erase(&moves->node, &sctx->pending_dir_moves);
3396 		RB_CLEAR_NODE(&moves->node);
3397 	}
3398 }
3399 
apply_children_dir_moves(struct send_ctx * sctx)3400 static int apply_children_dir_moves(struct send_ctx *sctx)
3401 {
3402 	struct pending_dir_move *pm;
3403 	struct list_head stack;
3404 	u64 parent_ino = sctx->cur_ino;
3405 	int ret = 0;
3406 
3407 	pm = get_pending_dir_moves(sctx, parent_ino);
3408 	if (!pm)
3409 		return 0;
3410 
3411 	INIT_LIST_HEAD(&stack);
3412 	tail_append_pending_moves(sctx, pm, &stack);
3413 
3414 	while (!list_empty(&stack)) {
3415 		pm = list_first_entry(&stack, struct pending_dir_move, list);
3416 		parent_ino = pm->ino;
3417 		ret = apply_dir_move(sctx, pm);
3418 		free_pending_move(sctx, pm);
3419 		if (ret)
3420 			goto out;
3421 		pm = get_pending_dir_moves(sctx, parent_ino);
3422 		if (pm)
3423 			tail_append_pending_moves(sctx, pm, &stack);
3424 	}
3425 	return 0;
3426 
3427 out:
3428 	while (!list_empty(&stack)) {
3429 		pm = list_first_entry(&stack, struct pending_dir_move, list);
3430 		free_pending_move(sctx, pm);
3431 	}
3432 	return ret;
3433 }
3434 
3435 /*
3436  * We might need to delay a directory rename even when no ancestor directory
3437  * (in the send root) with a higher inode number than ours (sctx->cur_ino) was
3438  * renamed. This happens when we rename a directory to the old name (the name
3439  * in the parent root) of some other unrelated directory that got its rename
3440  * delayed due to some ancestor with higher number that got renamed.
3441  *
3442  * Example:
3443  *
3444  * Parent snapshot:
3445  * .                                       (ino 256)
3446  * |---- a/                                (ino 257)
3447  * |     |---- file                        (ino 260)
3448  * |
3449  * |---- b/                                (ino 258)
3450  * |---- c/                                (ino 259)
3451  *
3452  * Send snapshot:
3453  * .                                       (ino 256)
3454  * |---- a/                                (ino 258)
3455  * |---- x/                                (ino 259)
3456  *       |---- y/                          (ino 257)
3457  *             |----- file                 (ino 260)
3458  *
3459  * Here we can not rename 258 from 'b' to 'a' without the rename of inode 257
3460  * from 'a' to 'x/y' happening first, which in turn depends on the rename of
3461  * inode 259 from 'c' to 'x'. So the order of rename commands the send stream
3462  * must issue is:
3463  *
3464  * 1 - rename 259 from 'c' to 'x'
3465  * 2 - rename 257 from 'a' to 'x/y'
3466  * 3 - rename 258 from 'b' to 'a'
3467  *
3468  * Returns 1 if the rename of sctx->cur_ino needs to be delayed, 0 if it can
3469  * be done right away and < 0 on error.
3470  */
wait_for_dest_dir_move(struct send_ctx * sctx,struct recorded_ref * parent_ref,const bool is_orphan)3471 static int wait_for_dest_dir_move(struct send_ctx *sctx,
3472 				  struct recorded_ref *parent_ref,
3473 				  const bool is_orphan)
3474 {
3475 	struct btrfs_fs_info *fs_info = sctx->parent_root->fs_info;
3476 	struct btrfs_path *path;
3477 	struct btrfs_key key;
3478 	struct btrfs_key di_key;
3479 	struct btrfs_dir_item *di;
3480 	u64 left_gen;
3481 	u64 right_gen;
3482 	int ret = 0;
3483 	struct waiting_dir_move *wdm;
3484 
3485 	if (RB_EMPTY_ROOT(&sctx->waiting_dir_moves))
3486 		return 0;
3487 
3488 	path = alloc_path_for_send();
3489 	if (!path)
3490 		return -ENOMEM;
3491 
3492 	key.objectid = parent_ref->dir;
3493 	key.type = BTRFS_DIR_ITEM_KEY;
3494 	key.offset = btrfs_name_hash(parent_ref->name, parent_ref->name_len);
3495 
3496 	ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0);
3497 	if (ret < 0) {
3498 		goto out;
3499 	} else if (ret > 0) {
3500 		ret = 0;
3501 		goto out;
3502 	}
3503 
3504 	di = btrfs_match_dir_item_name(fs_info, path, parent_ref->name,
3505 				       parent_ref->name_len);
3506 	if (!di) {
3507 		ret = 0;
3508 		goto out;
3509 	}
3510 	/*
3511 	 * di_key.objectid has the number of the inode that has a dentry in the
3512 	 * parent directory with the same name that sctx->cur_ino is being
3513 	 * renamed to. We need to check if that inode is in the send root as
3514 	 * well and if it is currently marked as an inode with a pending rename,
3515 	 * if it is, we need to delay the rename of sctx->cur_ino as well, so
3516 	 * that it happens after that other inode is renamed.
3517 	 */
3518 	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &di_key);
3519 	if (di_key.type != BTRFS_INODE_ITEM_KEY) {
3520 		ret = 0;
3521 		goto out;
3522 	}
3523 
3524 	ret = get_inode_info(sctx->parent_root, di_key.objectid, NULL,
3525 			     &left_gen, NULL, NULL, NULL, NULL);
3526 	if (ret < 0)
3527 		goto out;
3528 	ret = get_inode_info(sctx->send_root, di_key.objectid, NULL,
3529 			     &right_gen, NULL, NULL, NULL, NULL);
3530 	if (ret < 0) {
3531 		if (ret == -ENOENT)
3532 			ret = 0;
3533 		goto out;
3534 	}
3535 
3536 	/* Different inode, no need to delay the rename of sctx->cur_ino */
3537 	if (right_gen != left_gen) {
3538 		ret = 0;
3539 		goto out;
3540 	}
3541 
3542 	wdm = get_waiting_dir_move(sctx, di_key.objectid);
3543 	if (wdm && !wdm->orphanized) {
3544 		ret = add_pending_dir_move(sctx,
3545 					   sctx->cur_ino,
3546 					   sctx->cur_inode_gen,
3547 					   di_key.objectid,
3548 					   &sctx->new_refs,
3549 					   &sctx->deleted_refs,
3550 					   is_orphan);
3551 		if (!ret)
3552 			ret = 1;
3553 	}
3554 out:
3555 	btrfs_free_path(path);
3556 	return ret;
3557 }
3558 
3559 /*
3560  * Check if inode ino2, or any of its ancestors, is inode ino1.
3561  * Return 1 if true, 0 if false and < 0 on error.
3562  */
check_ino_in_path(struct btrfs_root * root,const u64 ino1,const u64 ino1_gen,const u64 ino2,const u64 ino2_gen,struct fs_path * fs_path)3563 static int check_ino_in_path(struct btrfs_root *root,
3564 			     const u64 ino1,
3565 			     const u64 ino1_gen,
3566 			     const u64 ino2,
3567 			     const u64 ino2_gen,
3568 			     struct fs_path *fs_path)
3569 {
3570 	u64 ino = ino2;
3571 
3572 	if (ino1 == ino2)
3573 		return ino1_gen == ino2_gen;
3574 
3575 	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
3576 		u64 parent;
3577 		u64 parent_gen;
3578 		int ret;
3579 
3580 		fs_path_reset(fs_path);
3581 		ret = get_first_ref(root, ino, &parent, &parent_gen, fs_path);
3582 		if (ret < 0)
3583 			return ret;
3584 		if (parent == ino1)
3585 			return parent_gen == ino1_gen;
3586 		ino = parent;
3587 	}
3588 	return 0;
3589 }
3590 
3591 /*
3592  * Check if ino ino1 is an ancestor of inode ino2 in the given root for any
3593  * possible path (in case ino2 is not a directory and has multiple hard links).
3594  * Return 1 if true, 0 if false and < 0 on error.
3595  */
is_ancestor(struct btrfs_root * root,const u64 ino1,const u64 ino1_gen,const u64 ino2,struct fs_path * fs_path)3596 static int is_ancestor(struct btrfs_root *root,
3597 		       const u64 ino1,
3598 		       const u64 ino1_gen,
3599 		       const u64 ino2,
3600 		       struct fs_path *fs_path)
3601 {
3602 	bool free_fs_path = false;
3603 	int ret = 0;
3604 	struct btrfs_path *path = NULL;
3605 	struct btrfs_key key;
3606 
3607 	if (!fs_path) {
3608 		fs_path = fs_path_alloc();
3609 		if (!fs_path)
3610 			return -ENOMEM;
3611 		free_fs_path = true;
3612 	}
3613 
3614 	path = alloc_path_for_send();
3615 	if (!path) {
3616 		ret = -ENOMEM;
3617 		goto out;
3618 	}
3619 
3620 	key.objectid = ino2;
3621 	key.type = BTRFS_INODE_REF_KEY;
3622 	key.offset = 0;
3623 
3624 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
3625 	if (ret < 0)
3626 		goto out;
3627 
3628 	while (true) {
3629 		struct extent_buffer *leaf = path->nodes[0];
3630 		int slot = path->slots[0];
3631 		u32 cur_offset = 0;
3632 		u32 item_size;
3633 
3634 		if (slot >= btrfs_header_nritems(leaf)) {
3635 			ret = btrfs_next_leaf(root, path);
3636 			if (ret < 0)
3637 				goto out;
3638 			if (ret > 0)
3639 				break;
3640 			continue;
3641 		}
3642 
3643 		btrfs_item_key_to_cpu(leaf, &key, slot);
3644 		if (key.objectid != ino2)
3645 			break;
3646 		if (key.type != BTRFS_INODE_REF_KEY &&
3647 		    key.type != BTRFS_INODE_EXTREF_KEY)
3648 			break;
3649 
3650 		item_size = btrfs_item_size_nr(leaf, slot);
3651 		while (cur_offset < item_size) {
3652 			u64 parent;
3653 			u64 parent_gen;
3654 
3655 			if (key.type == BTRFS_INODE_EXTREF_KEY) {
3656 				unsigned long ptr;
3657 				struct btrfs_inode_extref *extref;
3658 
3659 				ptr = btrfs_item_ptr_offset(leaf, slot);
3660 				extref = (struct btrfs_inode_extref *)
3661 					(ptr + cur_offset);
3662 				parent = btrfs_inode_extref_parent(leaf,
3663 								   extref);
3664 				cur_offset += sizeof(*extref);
3665 				cur_offset += btrfs_inode_extref_name_len(leaf,
3666 								  extref);
3667 			} else {
3668 				parent = key.offset;
3669 				cur_offset = item_size;
3670 			}
3671 
3672 			ret = get_inode_info(root, parent, NULL, &parent_gen,
3673 					     NULL, NULL, NULL, NULL);
3674 			if (ret < 0)
3675 				goto out;
3676 			ret = check_ino_in_path(root, ino1, ino1_gen,
3677 						parent, parent_gen, fs_path);
3678 			if (ret)
3679 				goto out;
3680 		}
3681 		path->slots[0]++;
3682 	}
3683 	ret = 0;
3684  out:
3685 	btrfs_free_path(path);
3686 	if (free_fs_path)
3687 		fs_path_free(fs_path);
3688 	return ret;
3689 }
3690 
wait_for_parent_move(struct send_ctx * sctx,struct recorded_ref * parent_ref,const bool is_orphan)3691 static int wait_for_parent_move(struct send_ctx *sctx,
3692 				struct recorded_ref *parent_ref,
3693 				const bool is_orphan)
3694 {
3695 	int ret = 0;
3696 	u64 ino = parent_ref->dir;
3697 	u64 ino_gen = parent_ref->dir_gen;
3698 	u64 parent_ino_before, parent_ino_after;
3699 	struct fs_path *path_before = NULL;
3700 	struct fs_path *path_after = NULL;
3701 	int len1, len2;
3702 
3703 	path_after = fs_path_alloc();
3704 	path_before = fs_path_alloc();
3705 	if (!path_after || !path_before) {
3706 		ret = -ENOMEM;
3707 		goto out;
3708 	}
3709 
3710 	/*
3711 	 * Our current directory inode may not yet be renamed/moved because some
3712 	 * ancestor (immediate or not) has to be renamed/moved first. So find if
3713 	 * such ancestor exists and make sure our own rename/move happens after
3714 	 * that ancestor is processed to avoid path build infinite loops (done
3715 	 * at get_cur_path()).
3716 	 */
3717 	while (ino > BTRFS_FIRST_FREE_OBJECTID) {
3718 		u64 parent_ino_after_gen;
3719 
3720 		if (is_waiting_for_move(sctx, ino)) {
3721 			/*
3722 			 * If the current inode is an ancestor of ino in the
3723 			 * parent root, we need to delay the rename of the
3724 			 * current inode, otherwise don't delayed the rename
3725 			 * because we can end up with a circular dependency
3726 			 * of renames, resulting in some directories never
3727 			 * getting the respective rename operations issued in
3728 			 * the send stream or getting into infinite path build
3729 			 * loops.
3730 			 */
3731 			ret = is_ancestor(sctx->parent_root,
3732 					  sctx->cur_ino, sctx->cur_inode_gen,
3733 					  ino, path_before);
3734 			if (ret)
3735 				break;
3736 		}
3737 
3738 		fs_path_reset(path_before);
3739 		fs_path_reset(path_after);
3740 
3741 		ret = get_first_ref(sctx->send_root, ino, &parent_ino_after,
3742 				    &parent_ino_after_gen, path_after);
3743 		if (ret < 0)
3744 			goto out;
3745 		ret = get_first_ref(sctx->parent_root, ino, &parent_ino_before,
3746 				    NULL, path_before);
3747 		if (ret < 0 && ret != -ENOENT) {
3748 			goto out;
3749 		} else if (ret == -ENOENT) {
3750 			ret = 0;
3751 			break;
3752 		}
3753 
3754 		len1 = fs_path_len(path_before);
3755 		len2 = fs_path_len(path_after);
3756 		if (ino > sctx->cur_ino &&
3757 		    (parent_ino_before != parent_ino_after || len1 != len2 ||
3758 		     memcmp(path_before->start, path_after->start, len1))) {
3759 			u64 parent_ino_gen;
3760 
3761 			ret = get_inode_info(sctx->parent_root, ino, NULL,
3762 					     &parent_ino_gen, NULL, NULL, NULL,
3763 					     NULL);
3764 			if (ret < 0)
3765 				goto out;
3766 			if (ino_gen == parent_ino_gen) {
3767 				ret = 1;
3768 				break;
3769 			}
3770 		}
3771 		ino = parent_ino_after;
3772 		ino_gen = parent_ino_after_gen;
3773 	}
3774 
3775 out:
3776 	fs_path_free(path_before);
3777 	fs_path_free(path_after);
3778 
3779 	if (ret == 1) {
3780 		ret = add_pending_dir_move(sctx,
3781 					   sctx->cur_ino,
3782 					   sctx->cur_inode_gen,
3783 					   ino,
3784 					   &sctx->new_refs,
3785 					   &sctx->deleted_refs,
3786 					   is_orphan);
3787 		if (!ret)
3788 			ret = 1;
3789 	}
3790 
3791 	return ret;
3792 }
3793 
update_ref_path(struct send_ctx * sctx,struct recorded_ref * ref)3794 static int update_ref_path(struct send_ctx *sctx, struct recorded_ref *ref)
3795 {
3796 	int ret;
3797 	struct fs_path *new_path;
3798 
3799 	/*
3800 	 * Our reference's name member points to its full_path member string, so
3801 	 * we use here a new path.
3802 	 */
3803 	new_path = fs_path_alloc();
3804 	if (!new_path)
3805 		return -ENOMEM;
3806 
3807 	ret = get_cur_path(sctx, ref->dir, ref->dir_gen, new_path);
3808 	if (ret < 0) {
3809 		fs_path_free(new_path);
3810 		return ret;
3811 	}
3812 	ret = fs_path_add(new_path, ref->name, ref->name_len);
3813 	if (ret < 0) {
3814 		fs_path_free(new_path);
3815 		return ret;
3816 	}
3817 
3818 	fs_path_free(ref->full_path);
3819 	set_ref_path(ref, new_path);
3820 
3821 	return 0;
3822 }
3823 
3824 /*
3825  * When processing the new references for an inode we may orphanize an existing
3826  * directory inode because its old name conflicts with one of the new references
3827  * of the current inode. Later, when processing another new reference of our
3828  * inode, we might need to orphanize another inode, but the path we have in the
3829  * reference reflects the pre-orphanization name of the directory we previously
3830  * orphanized. For example:
3831  *
3832  * parent snapshot looks like:
3833  *
3834  * .                                     (ino 256)
3835  * |----- f1                             (ino 257)
3836  * |----- f2                             (ino 258)
3837  * |----- d1/                            (ino 259)
3838  *        |----- d2/                     (ino 260)
3839  *
3840  * send snapshot looks like:
3841  *
3842  * .                                     (ino 256)
3843  * |----- d1                             (ino 258)
3844  * |----- f2/                            (ino 259)
3845  *        |----- f2_link/                (ino 260)
3846  *        |       |----- f1              (ino 257)
3847  *        |
3848  *        |----- d2                      (ino 258)
3849  *
3850  * When processing inode 257 we compute the name for inode 259 as "d1", and we
3851  * cache it in the name cache. Later when we start processing inode 258, when
3852  * collecting all its new references we set a full path of "d1/d2" for its new
3853  * reference with name "d2". When we start processing the new references we
3854  * start by processing the new reference with name "d1", and this results in
3855  * orphanizing inode 259, since its old reference causes a conflict. Then we
3856  * move on the next new reference, with name "d2", and we find out we must
3857  * orphanize inode 260, as its old reference conflicts with ours - but for the
3858  * orphanization we use a source path corresponding to the path we stored in the
3859  * new reference, which is "d1/d2" and not "o259-6-0/d2" - this makes the
3860  * receiver fail since the path component "d1/" no longer exists, it was renamed
3861  * to "o259-6-0/" when processing the previous new reference. So in this case we
3862  * must recompute the path in the new reference and use it for the new
3863  * orphanization operation.
3864  */
refresh_ref_path(struct send_ctx * sctx,struct recorded_ref * ref)3865 static int refresh_ref_path(struct send_ctx *sctx, struct recorded_ref *ref)
3866 {
3867 	char *name;
3868 	int ret;
3869 
3870 	name = kmemdup(ref->name, ref->name_len, GFP_KERNEL);
3871 	if (!name)
3872 		return -ENOMEM;
3873 
3874 	fs_path_reset(ref->full_path);
3875 	ret = get_cur_path(sctx, ref->dir, ref->dir_gen, ref->full_path);
3876 	if (ret < 0)
3877 		goto out;
3878 
3879 	ret = fs_path_add(ref->full_path, name, ref->name_len);
3880 	if (ret < 0)
3881 		goto out;
3882 
3883 	/* Update the reference's base name pointer. */
3884 	set_ref_path(ref, ref->full_path);
3885 out:
3886 	kfree(name);
3887 	return ret;
3888 }
3889 
3890 /*
3891  * This does all the move/link/unlink/rmdir magic.
3892  */
process_recorded_refs(struct send_ctx * sctx,int * pending_move)3893 static int process_recorded_refs(struct send_ctx *sctx, int *pending_move)
3894 {
3895 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
3896 	int ret = 0;
3897 	struct recorded_ref *cur;
3898 	struct recorded_ref *cur2;
3899 	struct list_head check_dirs;
3900 	struct fs_path *valid_path = NULL;
3901 	u64 ow_inode = 0;
3902 	u64 ow_gen;
3903 	u64 ow_mode;
3904 	int did_overwrite = 0;
3905 	int is_orphan = 0;
3906 	u64 last_dir_ino_rm = 0;
3907 	bool can_rename = true;
3908 	bool orphanized_dir = false;
3909 	bool orphanized_ancestor = false;
3910 
3911 	btrfs_debug(fs_info, "process_recorded_refs %llu", sctx->cur_ino);
3912 
3913 	/*
3914 	 * This should never happen as the root dir always has the same ref
3915 	 * which is always '..'
3916 	 */
3917 	BUG_ON(sctx->cur_ino <= BTRFS_FIRST_FREE_OBJECTID);
3918 	INIT_LIST_HEAD(&check_dirs);
3919 
3920 	valid_path = fs_path_alloc();
3921 	if (!valid_path) {
3922 		ret = -ENOMEM;
3923 		goto out;
3924 	}
3925 
3926 	/*
3927 	 * First, check if the first ref of the current inode was overwritten
3928 	 * before. If yes, we know that the current inode was already orphanized
3929 	 * and thus use the orphan name. If not, we can use get_cur_path to
3930 	 * get the path of the first ref as it would like while receiving at
3931 	 * this point in time.
3932 	 * New inodes are always orphan at the beginning, so force to use the
3933 	 * orphan name in this case.
3934 	 * The first ref is stored in valid_path and will be updated if it
3935 	 * gets moved around.
3936 	 */
3937 	if (!sctx->cur_inode_new) {
3938 		ret = did_overwrite_first_ref(sctx, sctx->cur_ino,
3939 				sctx->cur_inode_gen);
3940 		if (ret < 0)
3941 			goto out;
3942 		if (ret)
3943 			did_overwrite = 1;
3944 	}
3945 	if (sctx->cur_inode_new || did_overwrite) {
3946 		ret = gen_unique_name(sctx, sctx->cur_ino,
3947 				sctx->cur_inode_gen, valid_path);
3948 		if (ret < 0)
3949 			goto out;
3950 		is_orphan = 1;
3951 	} else {
3952 		ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen,
3953 				valid_path);
3954 		if (ret < 0)
3955 			goto out;
3956 	}
3957 
3958 	/*
3959 	 * Before doing any rename and link operations, do a first pass on the
3960 	 * new references to orphanize any unprocessed inodes that may have a
3961 	 * reference that conflicts with one of the new references of the current
3962 	 * inode. This needs to happen first because a new reference may conflict
3963 	 * with the old reference of a parent directory, so we must make sure
3964 	 * that the path used for link and rename commands don't use an
3965 	 * orphanized name when an ancestor was not yet orphanized.
3966 	 *
3967 	 * Example:
3968 	 *
3969 	 * Parent snapshot:
3970 	 *
3971 	 * .                                                      (ino 256)
3972 	 * |----- testdir/                                        (ino 259)
3973 	 * |          |----- a                                    (ino 257)
3974 	 * |
3975 	 * |----- b                                               (ino 258)
3976 	 *
3977 	 * Send snapshot:
3978 	 *
3979 	 * .                                                      (ino 256)
3980 	 * |----- testdir_2/                                      (ino 259)
3981 	 * |          |----- a                                    (ino 260)
3982 	 * |
3983 	 * |----- testdir                                         (ino 257)
3984 	 * |----- b                                               (ino 257)
3985 	 * |----- b2                                              (ino 258)
3986 	 *
3987 	 * Processing the new reference for inode 257 with name "b" may happen
3988 	 * before processing the new reference with name "testdir". If so, we
3989 	 * must make sure that by the time we send a link command to create the
3990 	 * hard link "b", inode 259 was already orphanized, since the generated
3991 	 * path in "valid_path" already contains the orphanized name for 259.
3992 	 * We are processing inode 257, so only later when processing 259 we do
3993 	 * the rename operation to change its temporary (orphanized) name to
3994 	 * "testdir_2".
3995 	 */
3996 	list_for_each_entry(cur, &sctx->new_refs, list) {
3997 		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
3998 		if (ret < 0)
3999 			goto out;
4000 		if (ret == inode_state_will_create)
4001 			continue;
4002 
4003 		/*
4004 		 * Check if this new ref would overwrite the first ref of another
4005 		 * unprocessed inode. If yes, orphanize the overwritten inode.
4006 		 * If we find an overwritten ref that is not the first ref,
4007 		 * simply unlink it.
4008 		 */
4009 		ret = will_overwrite_ref(sctx, cur->dir, cur->dir_gen,
4010 				cur->name, cur->name_len,
4011 				&ow_inode, &ow_gen, &ow_mode);
4012 		if (ret < 0)
4013 			goto out;
4014 		if (ret) {
4015 			ret = is_first_ref(sctx->parent_root,
4016 					   ow_inode, cur->dir, cur->name,
4017 					   cur->name_len);
4018 			if (ret < 0)
4019 				goto out;
4020 			if (ret) {
4021 				struct name_cache_entry *nce;
4022 				struct waiting_dir_move *wdm;
4023 
4024 				if (orphanized_dir) {
4025 					ret = refresh_ref_path(sctx, cur);
4026 					if (ret < 0)
4027 						goto out;
4028 				}
4029 
4030 				ret = orphanize_inode(sctx, ow_inode, ow_gen,
4031 						cur->full_path);
4032 				if (ret < 0)
4033 					goto out;
4034 				if (S_ISDIR(ow_mode))
4035 					orphanized_dir = true;
4036 
4037 				/*
4038 				 * If ow_inode has its rename operation delayed
4039 				 * make sure that its orphanized name is used in
4040 				 * the source path when performing its rename
4041 				 * operation.
4042 				 */
4043 				if (is_waiting_for_move(sctx, ow_inode)) {
4044 					wdm = get_waiting_dir_move(sctx,
4045 								   ow_inode);
4046 					ASSERT(wdm);
4047 					wdm->orphanized = true;
4048 				}
4049 
4050 				/*
4051 				 * Make sure we clear our orphanized inode's
4052 				 * name from the name cache. This is because the
4053 				 * inode ow_inode might be an ancestor of some
4054 				 * other inode that will be orphanized as well
4055 				 * later and has an inode number greater than
4056 				 * sctx->send_progress. We need to prevent
4057 				 * future name lookups from using the old name
4058 				 * and get instead the orphan name.
4059 				 */
4060 				nce = name_cache_search(sctx, ow_inode, ow_gen);
4061 				if (nce) {
4062 					name_cache_delete(sctx, nce);
4063 					kfree(nce);
4064 				}
4065 
4066 				/*
4067 				 * ow_inode might currently be an ancestor of
4068 				 * cur_ino, therefore compute valid_path (the
4069 				 * current path of cur_ino) again because it
4070 				 * might contain the pre-orphanization name of
4071 				 * ow_inode, which is no longer valid.
4072 				 */
4073 				ret = is_ancestor(sctx->parent_root,
4074 						  ow_inode, ow_gen,
4075 						  sctx->cur_ino, NULL);
4076 				if (ret > 0) {
4077 					orphanized_ancestor = true;
4078 					fs_path_reset(valid_path);
4079 					ret = get_cur_path(sctx, sctx->cur_ino,
4080 							   sctx->cur_inode_gen,
4081 							   valid_path);
4082 				}
4083 				if (ret < 0)
4084 					goto out;
4085 			} else {
4086 				/*
4087 				 * If we previously orphanized a directory that
4088 				 * collided with a new reference that we already
4089 				 * processed, recompute the current path because
4090 				 * that directory may be part of the path.
4091 				 */
4092 				if (orphanized_dir) {
4093 					ret = refresh_ref_path(sctx, cur);
4094 					if (ret < 0)
4095 						goto out;
4096 				}
4097 				ret = send_unlink(sctx, cur->full_path);
4098 				if (ret < 0)
4099 					goto out;
4100 			}
4101 		}
4102 
4103 	}
4104 
4105 	list_for_each_entry(cur, &sctx->new_refs, list) {
4106 		/*
4107 		 * We may have refs where the parent directory does not exist
4108 		 * yet. This happens if the parent directories inum is higher
4109 		 * than the current inum. To handle this case, we create the
4110 		 * parent directory out of order. But we need to check if this
4111 		 * did already happen before due to other refs in the same dir.
4112 		 */
4113 		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
4114 		if (ret < 0)
4115 			goto out;
4116 		if (ret == inode_state_will_create) {
4117 			ret = 0;
4118 			/*
4119 			 * First check if any of the current inodes refs did
4120 			 * already create the dir.
4121 			 */
4122 			list_for_each_entry(cur2, &sctx->new_refs, list) {
4123 				if (cur == cur2)
4124 					break;
4125 				if (cur2->dir == cur->dir) {
4126 					ret = 1;
4127 					break;
4128 				}
4129 			}
4130 
4131 			/*
4132 			 * If that did not happen, check if a previous inode
4133 			 * did already create the dir.
4134 			 */
4135 			if (!ret)
4136 				ret = did_create_dir(sctx, cur->dir);
4137 			if (ret < 0)
4138 				goto out;
4139 			if (!ret) {
4140 				ret = send_create_inode(sctx, cur->dir);
4141 				if (ret < 0)
4142 					goto out;
4143 			}
4144 		}
4145 
4146 		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root) {
4147 			ret = wait_for_dest_dir_move(sctx, cur, is_orphan);
4148 			if (ret < 0)
4149 				goto out;
4150 			if (ret == 1) {
4151 				can_rename = false;
4152 				*pending_move = 1;
4153 			}
4154 		}
4155 
4156 		if (S_ISDIR(sctx->cur_inode_mode) && sctx->parent_root &&
4157 		    can_rename) {
4158 			ret = wait_for_parent_move(sctx, cur, is_orphan);
4159 			if (ret < 0)
4160 				goto out;
4161 			if (ret == 1) {
4162 				can_rename = false;
4163 				*pending_move = 1;
4164 			}
4165 		}
4166 
4167 		/*
4168 		 * link/move the ref to the new place. If we have an orphan
4169 		 * inode, move it and update valid_path. If not, link or move
4170 		 * it depending on the inode mode.
4171 		 */
4172 		if (is_orphan && can_rename) {
4173 			ret = send_rename(sctx, valid_path, cur->full_path);
4174 			if (ret < 0)
4175 				goto out;
4176 			is_orphan = 0;
4177 			ret = fs_path_copy(valid_path, cur->full_path);
4178 			if (ret < 0)
4179 				goto out;
4180 		} else if (can_rename) {
4181 			if (S_ISDIR(sctx->cur_inode_mode)) {
4182 				/*
4183 				 * Dirs can't be linked, so move it. For moved
4184 				 * dirs, we always have one new and one deleted
4185 				 * ref. The deleted ref is ignored later.
4186 				 */
4187 				ret = send_rename(sctx, valid_path,
4188 						  cur->full_path);
4189 				if (!ret)
4190 					ret = fs_path_copy(valid_path,
4191 							   cur->full_path);
4192 				if (ret < 0)
4193 					goto out;
4194 			} else {
4195 				/*
4196 				 * We might have previously orphanized an inode
4197 				 * which is an ancestor of our current inode,
4198 				 * so our reference's full path, which was
4199 				 * computed before any such orphanizations, must
4200 				 * be updated.
4201 				 */
4202 				if (orphanized_dir) {
4203 					ret = update_ref_path(sctx, cur);
4204 					if (ret < 0)
4205 						goto out;
4206 				}
4207 				ret = send_link(sctx, cur->full_path,
4208 						valid_path);
4209 				if (ret < 0)
4210 					goto out;
4211 			}
4212 		}
4213 		ret = dup_ref(cur, &check_dirs);
4214 		if (ret < 0)
4215 			goto out;
4216 	}
4217 
4218 	if (S_ISDIR(sctx->cur_inode_mode) && sctx->cur_inode_deleted) {
4219 		/*
4220 		 * Check if we can already rmdir the directory. If not,
4221 		 * orphanize it. For every dir item inside that gets deleted
4222 		 * later, we do this check again and rmdir it then if possible.
4223 		 * See the use of check_dirs for more details.
4224 		 */
4225 		ret = can_rmdir(sctx, sctx->cur_ino, sctx->cur_inode_gen,
4226 				sctx->cur_ino);
4227 		if (ret < 0)
4228 			goto out;
4229 		if (ret) {
4230 			ret = send_rmdir(sctx, valid_path);
4231 			if (ret < 0)
4232 				goto out;
4233 		} else if (!is_orphan) {
4234 			ret = orphanize_inode(sctx, sctx->cur_ino,
4235 					sctx->cur_inode_gen, valid_path);
4236 			if (ret < 0)
4237 				goto out;
4238 			is_orphan = 1;
4239 		}
4240 
4241 		list_for_each_entry(cur, &sctx->deleted_refs, list) {
4242 			ret = dup_ref(cur, &check_dirs);
4243 			if (ret < 0)
4244 				goto out;
4245 		}
4246 	} else if (S_ISDIR(sctx->cur_inode_mode) &&
4247 		   !list_empty(&sctx->deleted_refs)) {
4248 		/*
4249 		 * We have a moved dir. Add the old parent to check_dirs
4250 		 */
4251 		cur = list_entry(sctx->deleted_refs.next, struct recorded_ref,
4252 				list);
4253 		ret = dup_ref(cur, &check_dirs);
4254 		if (ret < 0)
4255 			goto out;
4256 	} else if (!S_ISDIR(sctx->cur_inode_mode)) {
4257 		/*
4258 		 * We have a non dir inode. Go through all deleted refs and
4259 		 * unlink them if they were not already overwritten by other
4260 		 * inodes.
4261 		 */
4262 		list_for_each_entry(cur, &sctx->deleted_refs, list) {
4263 			ret = did_overwrite_ref(sctx, cur->dir, cur->dir_gen,
4264 					sctx->cur_ino, sctx->cur_inode_gen,
4265 					cur->name, cur->name_len);
4266 			if (ret < 0)
4267 				goto out;
4268 			if (!ret) {
4269 				/*
4270 				 * If we orphanized any ancestor before, we need
4271 				 * to recompute the full path for deleted names,
4272 				 * since any such path was computed before we
4273 				 * processed any references and orphanized any
4274 				 * ancestor inode.
4275 				 */
4276 				if (orphanized_ancestor) {
4277 					ret = update_ref_path(sctx, cur);
4278 					if (ret < 0)
4279 						goto out;
4280 				}
4281 				ret = send_unlink(sctx, cur->full_path);
4282 				if (ret < 0)
4283 					goto out;
4284 			}
4285 			ret = dup_ref(cur, &check_dirs);
4286 			if (ret < 0)
4287 				goto out;
4288 		}
4289 		/*
4290 		 * If the inode is still orphan, unlink the orphan. This may
4291 		 * happen when a previous inode did overwrite the first ref
4292 		 * of this inode and no new refs were added for the current
4293 		 * inode. Unlinking does not mean that the inode is deleted in
4294 		 * all cases. There may still be links to this inode in other
4295 		 * places.
4296 		 */
4297 		if (is_orphan) {
4298 			ret = send_unlink(sctx, valid_path);
4299 			if (ret < 0)
4300 				goto out;
4301 		}
4302 	}
4303 
4304 	/*
4305 	 * We did collect all parent dirs where cur_inode was once located. We
4306 	 * now go through all these dirs and check if they are pending for
4307 	 * deletion and if it's finally possible to perform the rmdir now.
4308 	 * We also update the inode stats of the parent dirs here.
4309 	 */
4310 	list_for_each_entry(cur, &check_dirs, list) {
4311 		/*
4312 		 * In case we had refs into dirs that were not processed yet,
4313 		 * we don't need to do the utime and rmdir logic for these dirs.
4314 		 * The dir will be processed later.
4315 		 */
4316 		if (cur->dir > sctx->cur_ino)
4317 			continue;
4318 
4319 		ret = get_cur_inode_state(sctx, cur->dir, cur->dir_gen);
4320 		if (ret < 0)
4321 			goto out;
4322 
4323 		if (ret == inode_state_did_create ||
4324 		    ret == inode_state_no_change) {
4325 			/* TODO delayed utimes */
4326 			ret = send_utimes(sctx, cur->dir, cur->dir_gen);
4327 			if (ret < 0)
4328 				goto out;
4329 		} else if (ret == inode_state_did_delete &&
4330 			   cur->dir != last_dir_ino_rm) {
4331 			ret = can_rmdir(sctx, cur->dir, cur->dir_gen,
4332 					sctx->cur_ino);
4333 			if (ret < 0)
4334 				goto out;
4335 			if (ret) {
4336 				ret = get_cur_path(sctx, cur->dir,
4337 						   cur->dir_gen, valid_path);
4338 				if (ret < 0)
4339 					goto out;
4340 				ret = send_rmdir(sctx, valid_path);
4341 				if (ret < 0)
4342 					goto out;
4343 				last_dir_ino_rm = cur->dir;
4344 			}
4345 		}
4346 	}
4347 
4348 	ret = 0;
4349 
4350 out:
4351 	__free_recorded_refs(&check_dirs);
4352 	free_recorded_refs(sctx);
4353 	fs_path_free(valid_path);
4354 	return ret;
4355 }
4356 
record_ref(struct btrfs_root * root,u64 dir,struct fs_path * name,void * ctx,struct list_head * refs)4357 static int record_ref(struct btrfs_root *root, u64 dir, struct fs_path *name,
4358 		      void *ctx, struct list_head *refs)
4359 {
4360 	int ret = 0;
4361 	struct send_ctx *sctx = ctx;
4362 	struct fs_path *p;
4363 	u64 gen;
4364 
4365 	p = fs_path_alloc();
4366 	if (!p)
4367 		return -ENOMEM;
4368 
4369 	ret = get_inode_info(root, dir, NULL, &gen, NULL, NULL,
4370 			NULL, NULL);
4371 	if (ret < 0)
4372 		goto out;
4373 
4374 	ret = get_cur_path(sctx, dir, gen, p);
4375 	if (ret < 0)
4376 		goto out;
4377 	ret = fs_path_add_path(p, name);
4378 	if (ret < 0)
4379 		goto out;
4380 
4381 	ret = __record_ref(refs, dir, gen, p);
4382 
4383 out:
4384 	if (ret)
4385 		fs_path_free(p);
4386 	return ret;
4387 }
4388 
__record_new_ref(int num,u64 dir,int index,struct fs_path * name,void * ctx)4389 static int __record_new_ref(int num, u64 dir, int index,
4390 			    struct fs_path *name,
4391 			    void *ctx)
4392 {
4393 	struct send_ctx *sctx = ctx;
4394 	return record_ref(sctx->send_root, dir, name, ctx, &sctx->new_refs);
4395 }
4396 
4397 
__record_deleted_ref(int num,u64 dir,int index,struct fs_path * name,void * ctx)4398 static int __record_deleted_ref(int num, u64 dir, int index,
4399 				struct fs_path *name,
4400 				void *ctx)
4401 {
4402 	struct send_ctx *sctx = ctx;
4403 	return record_ref(sctx->parent_root, dir, name, ctx,
4404 			  &sctx->deleted_refs);
4405 }
4406 
record_new_ref(struct send_ctx * sctx)4407 static int record_new_ref(struct send_ctx *sctx)
4408 {
4409 	int ret;
4410 
4411 	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
4412 				sctx->cmp_key, 0, __record_new_ref, sctx);
4413 	if (ret < 0)
4414 		goto out;
4415 	ret = 0;
4416 
4417 out:
4418 	return ret;
4419 }
4420 
record_deleted_ref(struct send_ctx * sctx)4421 static int record_deleted_ref(struct send_ctx *sctx)
4422 {
4423 	int ret;
4424 
4425 	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
4426 				sctx->cmp_key, 0, __record_deleted_ref, sctx);
4427 	if (ret < 0)
4428 		goto out;
4429 	ret = 0;
4430 
4431 out:
4432 	return ret;
4433 }
4434 
4435 struct find_ref_ctx {
4436 	u64 dir;
4437 	u64 dir_gen;
4438 	struct btrfs_root *root;
4439 	struct fs_path *name;
4440 	int found_idx;
4441 };
4442 
__find_iref(int num,u64 dir,int index,struct fs_path * name,void * ctx_)4443 static int __find_iref(int num, u64 dir, int index,
4444 		       struct fs_path *name,
4445 		       void *ctx_)
4446 {
4447 	struct find_ref_ctx *ctx = ctx_;
4448 	u64 dir_gen;
4449 	int ret;
4450 
4451 	if (dir == ctx->dir && fs_path_len(name) == fs_path_len(ctx->name) &&
4452 	    strncmp(name->start, ctx->name->start, fs_path_len(name)) == 0) {
4453 		/*
4454 		 * To avoid doing extra lookups we'll only do this if everything
4455 		 * else matches.
4456 		 */
4457 		ret = get_inode_info(ctx->root, dir, NULL, &dir_gen, NULL,
4458 				     NULL, NULL, NULL);
4459 		if (ret)
4460 			return ret;
4461 		if (dir_gen != ctx->dir_gen)
4462 			return 0;
4463 		ctx->found_idx = num;
4464 		return 1;
4465 	}
4466 	return 0;
4467 }
4468 
find_iref(struct btrfs_root * root,struct btrfs_path * path,struct btrfs_key * key,u64 dir,u64 dir_gen,struct fs_path * name)4469 static int find_iref(struct btrfs_root *root,
4470 		     struct btrfs_path *path,
4471 		     struct btrfs_key *key,
4472 		     u64 dir, u64 dir_gen, struct fs_path *name)
4473 {
4474 	int ret;
4475 	struct find_ref_ctx ctx;
4476 
4477 	ctx.dir = dir;
4478 	ctx.name = name;
4479 	ctx.dir_gen = dir_gen;
4480 	ctx.found_idx = -1;
4481 	ctx.root = root;
4482 
4483 	ret = iterate_inode_ref(root, path, key, 0, __find_iref, &ctx);
4484 	if (ret < 0)
4485 		return ret;
4486 
4487 	if (ctx.found_idx == -1)
4488 		return -ENOENT;
4489 
4490 	return ctx.found_idx;
4491 }
4492 
__record_changed_new_ref(int num,u64 dir,int index,struct fs_path * name,void * ctx)4493 static int __record_changed_new_ref(int num, u64 dir, int index,
4494 				    struct fs_path *name,
4495 				    void *ctx)
4496 {
4497 	u64 dir_gen;
4498 	int ret;
4499 	struct send_ctx *sctx = ctx;
4500 
4501 	ret = get_inode_info(sctx->send_root, dir, NULL, &dir_gen, NULL,
4502 			     NULL, NULL, NULL);
4503 	if (ret)
4504 		return ret;
4505 
4506 	ret = find_iref(sctx->parent_root, sctx->right_path,
4507 			sctx->cmp_key, dir, dir_gen, name);
4508 	if (ret == -ENOENT)
4509 		ret = __record_new_ref(num, dir, index, name, sctx);
4510 	else if (ret > 0)
4511 		ret = 0;
4512 
4513 	return ret;
4514 }
4515 
__record_changed_deleted_ref(int num,u64 dir,int index,struct fs_path * name,void * ctx)4516 static int __record_changed_deleted_ref(int num, u64 dir, int index,
4517 					struct fs_path *name,
4518 					void *ctx)
4519 {
4520 	u64 dir_gen;
4521 	int ret;
4522 	struct send_ctx *sctx = ctx;
4523 
4524 	ret = get_inode_info(sctx->parent_root, dir, NULL, &dir_gen, NULL,
4525 			     NULL, NULL, NULL);
4526 	if (ret)
4527 		return ret;
4528 
4529 	ret = find_iref(sctx->send_root, sctx->left_path, sctx->cmp_key,
4530 			dir, dir_gen, name);
4531 	if (ret == -ENOENT)
4532 		ret = __record_deleted_ref(num, dir, index, name, sctx);
4533 	else if (ret > 0)
4534 		ret = 0;
4535 
4536 	return ret;
4537 }
4538 
record_changed_ref(struct send_ctx * sctx)4539 static int record_changed_ref(struct send_ctx *sctx)
4540 {
4541 	int ret = 0;
4542 
4543 	ret = iterate_inode_ref(sctx->send_root, sctx->left_path,
4544 			sctx->cmp_key, 0, __record_changed_new_ref, sctx);
4545 	if (ret < 0)
4546 		goto out;
4547 	ret = iterate_inode_ref(sctx->parent_root, sctx->right_path,
4548 			sctx->cmp_key, 0, __record_changed_deleted_ref, sctx);
4549 	if (ret < 0)
4550 		goto out;
4551 	ret = 0;
4552 
4553 out:
4554 	return ret;
4555 }
4556 
4557 /*
4558  * Record and process all refs at once. Needed when an inode changes the
4559  * generation number, which means that it was deleted and recreated.
4560  */
process_all_refs(struct send_ctx * sctx,enum btrfs_compare_tree_result cmd)4561 static int process_all_refs(struct send_ctx *sctx,
4562 			    enum btrfs_compare_tree_result cmd)
4563 {
4564 	int ret;
4565 	struct btrfs_root *root;
4566 	struct btrfs_path *path;
4567 	struct btrfs_key key;
4568 	struct btrfs_key found_key;
4569 	struct extent_buffer *eb;
4570 	int slot;
4571 	iterate_inode_ref_t cb;
4572 	int pending_move = 0;
4573 
4574 	path = alloc_path_for_send();
4575 	if (!path)
4576 		return -ENOMEM;
4577 
4578 	if (cmd == BTRFS_COMPARE_TREE_NEW) {
4579 		root = sctx->send_root;
4580 		cb = __record_new_ref;
4581 	} else if (cmd == BTRFS_COMPARE_TREE_DELETED) {
4582 		root = sctx->parent_root;
4583 		cb = __record_deleted_ref;
4584 	} else {
4585 		btrfs_err(sctx->send_root->fs_info,
4586 				"Wrong command %d in process_all_refs", cmd);
4587 		ret = -EINVAL;
4588 		goto out;
4589 	}
4590 
4591 	key.objectid = sctx->cmp_key->objectid;
4592 	key.type = BTRFS_INODE_REF_KEY;
4593 	key.offset = 0;
4594 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4595 	if (ret < 0)
4596 		goto out;
4597 
4598 	while (1) {
4599 		eb = path->nodes[0];
4600 		slot = path->slots[0];
4601 		if (slot >= btrfs_header_nritems(eb)) {
4602 			ret = btrfs_next_leaf(root, path);
4603 			if (ret < 0)
4604 				goto out;
4605 			else if (ret > 0)
4606 				break;
4607 			continue;
4608 		}
4609 
4610 		btrfs_item_key_to_cpu(eb, &found_key, slot);
4611 
4612 		if (found_key.objectid != key.objectid ||
4613 		    (found_key.type != BTRFS_INODE_REF_KEY &&
4614 		     found_key.type != BTRFS_INODE_EXTREF_KEY))
4615 			break;
4616 
4617 		ret = iterate_inode_ref(root, path, &found_key, 0, cb, sctx);
4618 		if (ret < 0)
4619 			goto out;
4620 
4621 		path->slots[0]++;
4622 	}
4623 	btrfs_release_path(path);
4624 
4625 	/*
4626 	 * We don't actually care about pending_move as we are simply
4627 	 * re-creating this inode and will be rename'ing it into place once we
4628 	 * rename the parent directory.
4629 	 */
4630 	ret = process_recorded_refs(sctx, &pending_move);
4631 out:
4632 	btrfs_free_path(path);
4633 	return ret;
4634 }
4635 
send_set_xattr(struct send_ctx * sctx,struct fs_path * path,const char * name,int name_len,const char * data,int data_len)4636 static int send_set_xattr(struct send_ctx *sctx,
4637 			  struct fs_path *path,
4638 			  const char *name, int name_len,
4639 			  const char *data, int data_len)
4640 {
4641 	int ret = 0;
4642 
4643 	ret = begin_cmd(sctx, BTRFS_SEND_C_SET_XATTR);
4644 	if (ret < 0)
4645 		goto out;
4646 
4647 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
4648 	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
4649 	TLV_PUT(sctx, BTRFS_SEND_A_XATTR_DATA, data, data_len);
4650 
4651 	ret = send_cmd(sctx);
4652 
4653 tlv_put_failure:
4654 out:
4655 	return ret;
4656 }
4657 
send_remove_xattr(struct send_ctx * sctx,struct fs_path * path,const char * name,int name_len)4658 static int send_remove_xattr(struct send_ctx *sctx,
4659 			  struct fs_path *path,
4660 			  const char *name, int name_len)
4661 {
4662 	int ret = 0;
4663 
4664 	ret = begin_cmd(sctx, BTRFS_SEND_C_REMOVE_XATTR);
4665 	if (ret < 0)
4666 		goto out;
4667 
4668 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
4669 	TLV_PUT_STRING(sctx, BTRFS_SEND_A_XATTR_NAME, name, name_len);
4670 
4671 	ret = send_cmd(sctx);
4672 
4673 tlv_put_failure:
4674 out:
4675 	return ret;
4676 }
4677 
__process_new_xattr(int num,struct btrfs_key * di_key,const char * name,int name_len,const char * data,int data_len,u8 type,void * ctx)4678 static int __process_new_xattr(int num, struct btrfs_key *di_key,
4679 			       const char *name, int name_len,
4680 			       const char *data, int data_len,
4681 			       u8 type, void *ctx)
4682 {
4683 	int ret;
4684 	struct send_ctx *sctx = ctx;
4685 	struct fs_path *p;
4686 	struct posix_acl_xattr_header dummy_acl;
4687 
4688 	/* Capabilities are emitted by finish_inode_if_needed */
4689 	if (!strncmp(name, XATTR_NAME_CAPS, name_len))
4690 		return 0;
4691 
4692 	p = fs_path_alloc();
4693 	if (!p)
4694 		return -ENOMEM;
4695 
4696 	/*
4697 	 * This hack is needed because empty acls are stored as zero byte
4698 	 * data in xattrs. Problem with that is, that receiving these zero byte
4699 	 * acls will fail later. To fix this, we send a dummy acl list that
4700 	 * only contains the version number and no entries.
4701 	 */
4702 	if (!strncmp(name, XATTR_NAME_POSIX_ACL_ACCESS, name_len) ||
4703 	    !strncmp(name, XATTR_NAME_POSIX_ACL_DEFAULT, name_len)) {
4704 		if (data_len == 0) {
4705 			dummy_acl.a_version =
4706 					cpu_to_le32(POSIX_ACL_XATTR_VERSION);
4707 			data = (char *)&dummy_acl;
4708 			data_len = sizeof(dummy_acl);
4709 		}
4710 	}
4711 
4712 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4713 	if (ret < 0)
4714 		goto out;
4715 
4716 	ret = send_set_xattr(sctx, p, name, name_len, data, data_len);
4717 
4718 out:
4719 	fs_path_free(p);
4720 	return ret;
4721 }
4722 
__process_deleted_xattr(int num,struct btrfs_key * di_key,const char * name,int name_len,const char * data,int data_len,u8 type,void * ctx)4723 static int __process_deleted_xattr(int num, struct btrfs_key *di_key,
4724 				   const char *name, int name_len,
4725 				   const char *data, int data_len,
4726 				   u8 type, void *ctx)
4727 {
4728 	int ret;
4729 	struct send_ctx *sctx = ctx;
4730 	struct fs_path *p;
4731 
4732 	p = fs_path_alloc();
4733 	if (!p)
4734 		return -ENOMEM;
4735 
4736 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
4737 	if (ret < 0)
4738 		goto out;
4739 
4740 	ret = send_remove_xattr(sctx, p, name, name_len);
4741 
4742 out:
4743 	fs_path_free(p);
4744 	return ret;
4745 }
4746 
process_new_xattr(struct send_ctx * sctx)4747 static int process_new_xattr(struct send_ctx *sctx)
4748 {
4749 	int ret = 0;
4750 
4751 	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
4752 			       __process_new_xattr, sctx);
4753 
4754 	return ret;
4755 }
4756 
process_deleted_xattr(struct send_ctx * sctx)4757 static int process_deleted_xattr(struct send_ctx *sctx)
4758 {
4759 	return iterate_dir_item(sctx->parent_root, sctx->right_path,
4760 				__process_deleted_xattr, sctx);
4761 }
4762 
4763 struct find_xattr_ctx {
4764 	const char *name;
4765 	int name_len;
4766 	int found_idx;
4767 	char *found_data;
4768 	int found_data_len;
4769 };
4770 
__find_xattr(int num,struct btrfs_key * di_key,const char * name,int name_len,const char * data,int data_len,u8 type,void * vctx)4771 static int __find_xattr(int num, struct btrfs_key *di_key,
4772 			const char *name, int name_len,
4773 			const char *data, int data_len,
4774 			u8 type, void *vctx)
4775 {
4776 	struct find_xattr_ctx *ctx = vctx;
4777 
4778 	if (name_len == ctx->name_len &&
4779 	    strncmp(name, ctx->name, name_len) == 0) {
4780 		ctx->found_idx = num;
4781 		ctx->found_data_len = data_len;
4782 		ctx->found_data = kmemdup(data, data_len, GFP_KERNEL);
4783 		if (!ctx->found_data)
4784 			return -ENOMEM;
4785 		return 1;
4786 	}
4787 	return 0;
4788 }
4789 
find_xattr(struct btrfs_root * root,struct btrfs_path * path,struct btrfs_key * key,const char * name,int name_len,char ** data,int * data_len)4790 static int find_xattr(struct btrfs_root *root,
4791 		      struct btrfs_path *path,
4792 		      struct btrfs_key *key,
4793 		      const char *name, int name_len,
4794 		      char **data, int *data_len)
4795 {
4796 	int ret;
4797 	struct find_xattr_ctx ctx;
4798 
4799 	ctx.name = name;
4800 	ctx.name_len = name_len;
4801 	ctx.found_idx = -1;
4802 	ctx.found_data = NULL;
4803 	ctx.found_data_len = 0;
4804 
4805 	ret = iterate_dir_item(root, path, __find_xattr, &ctx);
4806 	if (ret < 0)
4807 		return ret;
4808 
4809 	if (ctx.found_idx == -1)
4810 		return -ENOENT;
4811 	if (data) {
4812 		*data = ctx.found_data;
4813 		*data_len = ctx.found_data_len;
4814 	} else {
4815 		kfree(ctx.found_data);
4816 	}
4817 	return ctx.found_idx;
4818 }
4819 
4820 
__process_changed_new_xattr(int num,struct btrfs_key * di_key,const char * name,int name_len,const char * data,int data_len,u8 type,void * ctx)4821 static int __process_changed_new_xattr(int num, struct btrfs_key *di_key,
4822 				       const char *name, int name_len,
4823 				       const char *data, int data_len,
4824 				       u8 type, void *ctx)
4825 {
4826 	int ret;
4827 	struct send_ctx *sctx = ctx;
4828 	char *found_data = NULL;
4829 	int found_data_len  = 0;
4830 
4831 	ret = find_xattr(sctx->parent_root, sctx->right_path,
4832 			 sctx->cmp_key, name, name_len, &found_data,
4833 			 &found_data_len);
4834 	if (ret == -ENOENT) {
4835 		ret = __process_new_xattr(num, di_key, name, name_len, data,
4836 				data_len, type, ctx);
4837 	} else if (ret >= 0) {
4838 		if (data_len != found_data_len ||
4839 		    memcmp(data, found_data, data_len)) {
4840 			ret = __process_new_xattr(num, di_key, name, name_len,
4841 					data, data_len, type, ctx);
4842 		} else {
4843 			ret = 0;
4844 		}
4845 	}
4846 
4847 	kfree(found_data);
4848 	return ret;
4849 }
4850 
__process_changed_deleted_xattr(int num,struct btrfs_key * di_key,const char * name,int name_len,const char * data,int data_len,u8 type,void * ctx)4851 static int __process_changed_deleted_xattr(int num, struct btrfs_key *di_key,
4852 					   const char *name, int name_len,
4853 					   const char *data, int data_len,
4854 					   u8 type, void *ctx)
4855 {
4856 	int ret;
4857 	struct send_ctx *sctx = ctx;
4858 
4859 	ret = find_xattr(sctx->send_root, sctx->left_path, sctx->cmp_key,
4860 			 name, name_len, NULL, NULL);
4861 	if (ret == -ENOENT)
4862 		ret = __process_deleted_xattr(num, di_key, name, name_len, data,
4863 				data_len, type, ctx);
4864 	else if (ret >= 0)
4865 		ret = 0;
4866 
4867 	return ret;
4868 }
4869 
process_changed_xattr(struct send_ctx * sctx)4870 static int process_changed_xattr(struct send_ctx *sctx)
4871 {
4872 	int ret = 0;
4873 
4874 	ret = iterate_dir_item(sctx->send_root, sctx->left_path,
4875 			__process_changed_new_xattr, sctx);
4876 	if (ret < 0)
4877 		goto out;
4878 	ret = iterate_dir_item(sctx->parent_root, sctx->right_path,
4879 			__process_changed_deleted_xattr, sctx);
4880 
4881 out:
4882 	return ret;
4883 }
4884 
process_all_new_xattrs(struct send_ctx * sctx)4885 static int process_all_new_xattrs(struct send_ctx *sctx)
4886 {
4887 	int ret;
4888 	struct btrfs_root *root;
4889 	struct btrfs_path *path;
4890 	struct btrfs_key key;
4891 	struct btrfs_key found_key;
4892 	struct extent_buffer *eb;
4893 	int slot;
4894 
4895 	path = alloc_path_for_send();
4896 	if (!path)
4897 		return -ENOMEM;
4898 
4899 	root = sctx->send_root;
4900 
4901 	key.objectid = sctx->cmp_key->objectid;
4902 	key.type = BTRFS_XATTR_ITEM_KEY;
4903 	key.offset = 0;
4904 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4905 	if (ret < 0)
4906 		goto out;
4907 
4908 	while (1) {
4909 		eb = path->nodes[0];
4910 		slot = path->slots[0];
4911 		if (slot >= btrfs_header_nritems(eb)) {
4912 			ret = btrfs_next_leaf(root, path);
4913 			if (ret < 0) {
4914 				goto out;
4915 			} else if (ret > 0) {
4916 				ret = 0;
4917 				break;
4918 			}
4919 			continue;
4920 		}
4921 
4922 		btrfs_item_key_to_cpu(eb, &found_key, slot);
4923 		if (found_key.objectid != key.objectid ||
4924 		    found_key.type != key.type) {
4925 			ret = 0;
4926 			goto out;
4927 		}
4928 
4929 		ret = iterate_dir_item(root, path, __process_new_xattr, sctx);
4930 		if (ret < 0)
4931 			goto out;
4932 
4933 		path->slots[0]++;
4934 	}
4935 
4936 out:
4937 	btrfs_free_path(path);
4938 	return ret;
4939 }
4940 
max_send_read_size(const struct send_ctx * sctx)4941 static inline u64 max_send_read_size(const struct send_ctx *sctx)
4942 {
4943 	return sctx->send_max_size - SZ_16K;
4944 }
4945 
put_data_header(struct send_ctx * sctx,u32 len)4946 static int put_data_header(struct send_ctx *sctx, u32 len)
4947 {
4948 	struct btrfs_tlv_header *hdr;
4949 
4950 	if (sctx->send_max_size - sctx->send_size < sizeof(*hdr) + len)
4951 		return -EOVERFLOW;
4952 	hdr = (struct btrfs_tlv_header *)(sctx->send_buf + sctx->send_size);
4953 	put_unaligned_le16(BTRFS_SEND_A_DATA, &hdr->tlv_type);
4954 	put_unaligned_le16(len, &hdr->tlv_len);
4955 	sctx->send_size += sizeof(*hdr);
4956 	return 0;
4957 }
4958 
put_file_data(struct send_ctx * sctx,u64 offset,u32 len)4959 static int put_file_data(struct send_ctx *sctx, u64 offset, u32 len)
4960 {
4961 	struct btrfs_root *root = sctx->send_root;
4962 	struct btrfs_fs_info *fs_info = root->fs_info;
4963 	struct inode *inode;
4964 	struct page *page;
4965 	pgoff_t index = offset >> PAGE_SHIFT;
4966 	pgoff_t last_index;
4967 	unsigned pg_offset = offset_in_page(offset);
4968 	int ret;
4969 
4970 	ret = put_data_header(sctx, len);
4971 	if (ret)
4972 		return ret;
4973 
4974 	inode = btrfs_iget(fs_info->sb, sctx->cur_ino, root);
4975 	if (IS_ERR(inode))
4976 		return PTR_ERR(inode);
4977 
4978 	last_index = (offset + len - 1) >> PAGE_SHIFT;
4979 
4980 	/* initial readahead */
4981 	memset(&sctx->ra, 0, sizeof(struct file_ra_state));
4982 	file_ra_state_init(&sctx->ra, inode->i_mapping);
4983 
4984 	while (index <= last_index) {
4985 		unsigned cur_len = min_t(unsigned, len,
4986 					 PAGE_SIZE - pg_offset);
4987 
4988 		page = find_lock_page(inode->i_mapping, index);
4989 		if (!page) {
4990 			page_cache_sync_readahead(inode->i_mapping, &sctx->ra,
4991 				NULL, index, last_index + 1 - index);
4992 
4993 			page = find_or_create_page(inode->i_mapping, index,
4994 					GFP_KERNEL);
4995 			if (!page) {
4996 				ret = -ENOMEM;
4997 				break;
4998 			}
4999 		}
5000 
5001 		if (PageReadahead(page)) {
5002 			page_cache_async_readahead(inode->i_mapping, &sctx->ra,
5003 				NULL, page, index, last_index + 1 - index);
5004 		}
5005 
5006 		if (!PageUptodate(page)) {
5007 			btrfs_readpage(NULL, page);
5008 			lock_page(page);
5009 			if (!PageUptodate(page)) {
5010 				unlock_page(page);
5011 				btrfs_err(fs_info,
5012 			"send: IO error at offset %llu for inode %llu root %llu",
5013 					page_offset(page), sctx->cur_ino,
5014 					sctx->send_root->root_key.objectid);
5015 				put_page(page);
5016 				ret = -EIO;
5017 				break;
5018 			}
5019 		}
5020 
5021 		memcpy_from_page(sctx->send_buf + sctx->send_size, page,
5022 				 pg_offset, cur_len);
5023 		unlock_page(page);
5024 		put_page(page);
5025 		index++;
5026 		pg_offset = 0;
5027 		len -= cur_len;
5028 		sctx->send_size += cur_len;
5029 	}
5030 	iput(inode);
5031 	return ret;
5032 }
5033 
5034 /*
5035  * Read some bytes from the current inode/file and send a write command to
5036  * user space.
5037  */
send_write(struct send_ctx * sctx,u64 offset,u32 len)5038 static int send_write(struct send_ctx *sctx, u64 offset, u32 len)
5039 {
5040 	struct btrfs_fs_info *fs_info = sctx->send_root->fs_info;
5041 	int ret = 0;
5042 	struct fs_path *p;
5043 
5044 	p = fs_path_alloc();
5045 	if (!p)
5046 		return -ENOMEM;
5047 
5048 	btrfs_debug(fs_info, "send_write offset=%llu, len=%d", offset, len);
5049 
5050 	ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
5051 	if (ret < 0)
5052 		goto out;
5053 
5054 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5055 	if (ret < 0)
5056 		goto out;
5057 
5058 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5059 	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5060 	ret = put_file_data(sctx, offset, len);
5061 	if (ret < 0)
5062 		goto out;
5063 
5064 	ret = send_cmd(sctx);
5065 
5066 tlv_put_failure:
5067 out:
5068 	fs_path_free(p);
5069 	return ret;
5070 }
5071 
5072 /*
5073  * Send a clone command to user space.
5074  */
send_clone(struct send_ctx * sctx,u64 offset,u32 len,struct clone_root * clone_root)5075 static int send_clone(struct send_ctx *sctx,
5076 		      u64 offset, u32 len,
5077 		      struct clone_root *clone_root)
5078 {
5079 	int ret = 0;
5080 	struct fs_path *p;
5081 	u64 gen;
5082 
5083 	btrfs_debug(sctx->send_root->fs_info,
5084 		    "send_clone offset=%llu, len=%d, clone_root=%llu, clone_inode=%llu, clone_offset=%llu",
5085 		    offset, len, clone_root->root->root_key.objectid,
5086 		    clone_root->ino, clone_root->offset);
5087 
5088 	p = fs_path_alloc();
5089 	if (!p)
5090 		return -ENOMEM;
5091 
5092 	ret = begin_cmd(sctx, BTRFS_SEND_C_CLONE);
5093 	if (ret < 0)
5094 		goto out;
5095 
5096 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5097 	if (ret < 0)
5098 		goto out;
5099 
5100 	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5101 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_LEN, len);
5102 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5103 
5104 	if (clone_root->root == sctx->send_root) {
5105 		ret = get_inode_info(sctx->send_root, clone_root->ino, NULL,
5106 				&gen, NULL, NULL, NULL, NULL);
5107 		if (ret < 0)
5108 			goto out;
5109 		ret = get_cur_path(sctx, clone_root->ino, gen, p);
5110 	} else {
5111 		ret = get_inode_path(clone_root->root, clone_root->ino, p);
5112 	}
5113 	if (ret < 0)
5114 		goto out;
5115 
5116 	/*
5117 	 * If the parent we're using has a received_uuid set then use that as
5118 	 * our clone source as that is what we will look for when doing a
5119 	 * receive.
5120 	 *
5121 	 * This covers the case that we create a snapshot off of a received
5122 	 * subvolume and then use that as the parent and try to receive on a
5123 	 * different host.
5124 	 */
5125 	if (!btrfs_is_empty_uuid(clone_root->root->root_item.received_uuid))
5126 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
5127 			     clone_root->root->root_item.received_uuid);
5128 	else
5129 		TLV_PUT_UUID(sctx, BTRFS_SEND_A_CLONE_UUID,
5130 			     clone_root->root->root_item.uuid);
5131 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_CTRANSID,
5132 		    btrfs_root_ctransid(&clone_root->root->root_item));
5133 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_CLONE_PATH, p);
5134 	TLV_PUT_U64(sctx, BTRFS_SEND_A_CLONE_OFFSET,
5135 			clone_root->offset);
5136 
5137 	ret = send_cmd(sctx);
5138 
5139 tlv_put_failure:
5140 out:
5141 	fs_path_free(p);
5142 	return ret;
5143 }
5144 
5145 /*
5146  * Send an update extent command to user space.
5147  */
send_update_extent(struct send_ctx * sctx,u64 offset,u32 len)5148 static int send_update_extent(struct send_ctx *sctx,
5149 			      u64 offset, u32 len)
5150 {
5151 	int ret = 0;
5152 	struct fs_path *p;
5153 
5154 	p = fs_path_alloc();
5155 	if (!p)
5156 		return -ENOMEM;
5157 
5158 	ret = begin_cmd(sctx, BTRFS_SEND_C_UPDATE_EXTENT);
5159 	if (ret < 0)
5160 		goto out;
5161 
5162 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5163 	if (ret < 0)
5164 		goto out;
5165 
5166 	TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5167 	TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5168 	TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, len);
5169 
5170 	ret = send_cmd(sctx);
5171 
5172 tlv_put_failure:
5173 out:
5174 	fs_path_free(p);
5175 	return ret;
5176 }
5177 
send_hole(struct send_ctx * sctx,u64 end)5178 static int send_hole(struct send_ctx *sctx, u64 end)
5179 {
5180 	struct fs_path *p = NULL;
5181 	u64 read_size = max_send_read_size(sctx);
5182 	u64 offset = sctx->cur_inode_last_extent;
5183 	int ret = 0;
5184 
5185 	/*
5186 	 * A hole that starts at EOF or beyond it. Since we do not yet support
5187 	 * fallocate (for extent preallocation and hole punching), sending a
5188 	 * write of zeroes starting at EOF or beyond would later require issuing
5189 	 * a truncate operation which would undo the write and achieve nothing.
5190 	 */
5191 	if (offset >= sctx->cur_inode_size)
5192 		return 0;
5193 
5194 	/*
5195 	 * Don't go beyond the inode's i_size due to prealloc extents that start
5196 	 * after the i_size.
5197 	 */
5198 	end = min_t(u64, end, sctx->cur_inode_size);
5199 
5200 	if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
5201 		return send_update_extent(sctx, offset, end - offset);
5202 
5203 	p = fs_path_alloc();
5204 	if (!p)
5205 		return -ENOMEM;
5206 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, p);
5207 	if (ret < 0)
5208 		goto tlv_put_failure;
5209 	while (offset < end) {
5210 		u64 len = min(end - offset, read_size);
5211 
5212 		ret = begin_cmd(sctx, BTRFS_SEND_C_WRITE);
5213 		if (ret < 0)
5214 			break;
5215 		TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, p);
5216 		TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
5217 		ret = put_data_header(sctx, len);
5218 		if (ret < 0)
5219 			break;
5220 		memset(sctx->send_buf + sctx->send_size, 0, len);
5221 		sctx->send_size += len;
5222 		ret = send_cmd(sctx);
5223 		if (ret < 0)
5224 			break;
5225 		offset += len;
5226 	}
5227 	sctx->cur_inode_next_write_offset = offset;
5228 tlv_put_failure:
5229 	fs_path_free(p);
5230 	return ret;
5231 }
5232 
send_extent_data(struct send_ctx * sctx,const u64 offset,const u64 len)5233 static int send_extent_data(struct send_ctx *sctx,
5234 			    const u64 offset,
5235 			    const u64 len)
5236 {
5237 	u64 read_size = max_send_read_size(sctx);
5238 	u64 sent = 0;
5239 
5240 	if (sctx->flags & BTRFS_SEND_FLAG_NO_FILE_DATA)
5241 		return send_update_extent(sctx, offset, len);
5242 
5243 	while (sent < len) {
5244 		u64 size = min(len - sent, read_size);
5245 		int ret;
5246 
5247 		ret = send_write(sctx, offset + sent, size);
5248 		if (ret < 0)
5249 			return ret;
5250 		sent += size;
5251 	}
5252 	return 0;
5253 }
5254 
5255 /*
5256  * Search for a capability xattr related to sctx->cur_ino. If the capability is
5257  * found, call send_set_xattr function to emit it.
5258  *
5259  * Return 0 if there isn't a capability, or when the capability was emitted
5260  * successfully, or < 0 if an error occurred.
5261  */
send_capabilities(struct send_ctx * sctx)5262 static int send_capabilities(struct send_ctx *sctx)
5263 {
5264 	struct fs_path *fspath = NULL;
5265 	struct btrfs_path *path;
5266 	struct btrfs_dir_item *di;
5267 	struct extent_buffer *leaf;
5268 	unsigned long data_ptr;
5269 	char *buf = NULL;
5270 	int buf_len;
5271 	int ret = 0;
5272 
5273 	path = alloc_path_for_send();
5274 	if (!path)
5275 		return -ENOMEM;
5276 
5277 	di = btrfs_lookup_xattr(NULL, sctx->send_root, path, sctx->cur_ino,
5278 				XATTR_NAME_CAPS, strlen(XATTR_NAME_CAPS), 0);
5279 	if (!di) {
5280 		/* There is no xattr for this inode */
5281 		goto out;
5282 	} else if (IS_ERR(di)) {
5283 		ret = PTR_ERR(di);
5284 		goto out;
5285 	}
5286 
5287 	leaf = path->nodes[0];
5288 	buf_len = btrfs_dir_data_len(leaf, di);
5289 
5290 	fspath = fs_path_alloc();
5291 	buf = kmalloc(buf_len, GFP_KERNEL);
5292 	if (!fspath || !buf) {
5293 		ret = -ENOMEM;
5294 		goto out;
5295 	}
5296 
5297 	ret = get_cur_path(sctx, sctx->cur_ino, sctx->cur_inode_gen, fspath);
5298 	if (ret < 0)
5299 		goto out;
5300 
5301 	data_ptr = (unsigned long)(di + 1) + btrfs_dir_name_len(leaf, di);
5302 	read_extent_buffer(leaf, buf, data_ptr, buf_len);
5303 
5304 	ret = send_set_xattr(sctx, fspath, XATTR_NAME_CAPS,
5305 			strlen(XATTR_NAME_CAPS), buf, buf_len);
5306 out:
5307 	kfree(buf);
5308 	fs_path_free(fspath);
5309 	btrfs_free_path(path);
5310 	return ret;
5311 }
5312 
clone_range(struct send_ctx * sctx,struct clone_root * clone_root,const u64 disk_byte,u64 data_offset,u64 offset,u64 len)5313 static int clone_range(struct send_ctx *sctx,
5314 		       struct clone_root *clone_root,
5315 		       const u64 disk_byte,
5316 		       u64 data_offset,
5317 		       u64 offset,
5318 		       u64 len)
5319 {
5320 	struct btrfs_path *path;
5321 	struct btrfs_key key;
5322 	int ret;
5323 	u64 clone_src_i_size = 0;
5324 
5325 	/*
5326 	 * Prevent cloning from a zero offset with a length matching the sector
5327 	 * size because in some scenarios this will make the receiver fail.
5328 	 *
5329 	 * For example, if in the source filesystem the extent at offset 0
5330 	 * has a length of sectorsize and it was written using direct IO, then
5331 	 * it can never be an inline extent (even if compression is enabled).
5332 	 * Then this extent can be cloned in the original filesystem to a non
5333 	 * zero file offset, but it may not be possible to clone in the
5334 	 * destination filesystem because it can be inlined due to compression
5335 	 * on the destination filesystem (as the receiver's write operations are
5336 	 * always done using buffered IO). The same happens when the original
5337 	 * filesystem does not have compression enabled but the destination
5338 	 * filesystem has.
5339 	 */
5340 	if (clone_root->offset == 0 &&
5341 	    len == sctx->send_root->fs_info->sectorsize)
5342 		return send_extent_data(sctx, offset, len);
5343 
5344 	path = alloc_path_for_send();
5345 	if (!path)
5346 		return -ENOMEM;
5347 
5348 	/*
5349 	 * There are inodes that have extents that lie behind its i_size. Don't
5350 	 * accept clones from these extents.
5351 	 */
5352 	ret = __get_inode_info(clone_root->root, path, clone_root->ino,
5353 			       &clone_src_i_size, NULL, NULL, NULL, NULL, NULL);
5354 	btrfs_release_path(path);
5355 	if (ret < 0)
5356 		goto out;
5357 
5358 	/*
5359 	 * We can't send a clone operation for the entire range if we find
5360 	 * extent items in the respective range in the source file that
5361 	 * refer to different extents or if we find holes.
5362 	 * So check for that and do a mix of clone and regular write/copy
5363 	 * operations if needed.
5364 	 *
5365 	 * Example:
5366 	 *
5367 	 * mkfs.btrfs -f /dev/sda
5368 	 * mount /dev/sda /mnt
5369 	 * xfs_io -f -c "pwrite -S 0xaa 0K 100K" /mnt/foo
5370 	 * cp --reflink=always /mnt/foo /mnt/bar
5371 	 * xfs_io -c "pwrite -S 0xbb 50K 50K" /mnt/foo
5372 	 * btrfs subvolume snapshot -r /mnt /mnt/snap
5373 	 *
5374 	 * If when we send the snapshot and we are processing file bar (which
5375 	 * has a higher inode number than foo) we blindly send a clone operation
5376 	 * for the [0, 100K[ range from foo to bar, the receiver ends up getting
5377 	 * a file bar that matches the content of file foo - iow, doesn't match
5378 	 * the content from bar in the original filesystem.
5379 	 */
5380 	key.objectid = clone_root->ino;
5381 	key.type = BTRFS_EXTENT_DATA_KEY;
5382 	key.offset = clone_root->offset;
5383 	ret = btrfs_search_slot(NULL, clone_root->root, &key, path, 0, 0);
5384 	if (ret < 0)
5385 		goto out;
5386 	if (ret > 0 && path->slots[0] > 0) {
5387 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0] - 1);
5388 		if (key.objectid == clone_root->ino &&
5389 		    key.type == BTRFS_EXTENT_DATA_KEY)
5390 			path->slots[0]--;
5391 	}
5392 
5393 	while (true) {
5394 		struct extent_buffer *leaf = path->nodes[0];
5395 		int slot = path->slots[0];
5396 		struct btrfs_file_extent_item *ei;
5397 		u8 type;
5398 		u64 ext_len;
5399 		u64 clone_len;
5400 		u64 clone_data_offset;
5401 		bool crossed_src_i_size = false;
5402 
5403 		if (slot >= btrfs_header_nritems(leaf)) {
5404 			ret = btrfs_next_leaf(clone_root->root, path);
5405 			if (ret < 0)
5406 				goto out;
5407 			else if (ret > 0)
5408 				break;
5409 			continue;
5410 		}
5411 
5412 		btrfs_item_key_to_cpu(leaf, &key, slot);
5413 
5414 		/*
5415 		 * We might have an implicit trailing hole (NO_HOLES feature
5416 		 * enabled). We deal with it after leaving this loop.
5417 		 */
5418 		if (key.objectid != clone_root->ino ||
5419 		    key.type != BTRFS_EXTENT_DATA_KEY)
5420 			break;
5421 
5422 		ei = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
5423 		type = btrfs_file_extent_type(leaf, ei);
5424 		if (type == BTRFS_FILE_EXTENT_INLINE) {
5425 			ext_len = btrfs_file_extent_ram_bytes(leaf, ei);
5426 			ext_len = PAGE_ALIGN(ext_len);
5427 		} else {
5428 			ext_len = btrfs_file_extent_num_bytes(leaf, ei);
5429 		}
5430 
5431 		if (key.offset + ext_len <= clone_root->offset)
5432 			goto next;
5433 
5434 		if (key.offset > clone_root->offset) {
5435 			/* Implicit hole, NO_HOLES feature enabled. */
5436 			u64 hole_len = key.offset - clone_root->offset;
5437 
5438 			if (hole_len > len)
5439 				hole_len = len;
5440 			ret = send_extent_data(sctx, offset, hole_len);
5441 			if (ret < 0)
5442 				goto out;
5443 
5444 			len -= hole_len;
5445 			if (len == 0)
5446 				break;
5447 			offset += hole_len;
5448 			clone_root->offset += hole_len;
5449 			data_offset += hole_len;
5450 		}
5451 
5452 		if (key.offset >= clone_root->offset + len)
5453 			break;
5454 
5455 		if (key.offset >= clone_src_i_size)
5456 			break;
5457 
5458 		if (key.offset + ext_len > clone_src_i_size) {
5459 			ext_len = clone_src_i_size - key.offset;
5460 			crossed_src_i_size = true;
5461 		}
5462 
5463 		clone_data_offset = btrfs_file_extent_offset(leaf, ei);
5464 		if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte) {
5465 			clone_root->offset = key.offset;
5466 			if (clone_data_offset < data_offset &&
5467 				clone_data_offset + ext_len > data_offset) {
5468 				u64 extent_offset;
5469 
5470 				extent_offset = data_offset - clone_data_offset;
5471 				ext_len -= extent_offset;
5472 				clone_data_offset += extent_offset;
5473 				clone_root->offset += extent_offset;
5474 			}
5475 		}
5476 
5477 		clone_len = min_t(u64, ext_len, len);
5478 
5479 		if (btrfs_file_extent_disk_bytenr(leaf, ei) == disk_byte &&
5480 		    clone_data_offset == data_offset) {
5481 			const u64 src_end = clone_root->offset + clone_len;
5482 			const u64 sectorsize = SZ_64K;
5483 
5484 			/*
5485 			 * We can't clone the last block, when its size is not
5486 			 * sector size aligned, into the middle of a file. If we
5487 			 * do so, the receiver will get a failure (-EINVAL) when
5488 			 * trying to clone or will silently corrupt the data in
5489 			 * the destination file if it's on a kernel without the
5490 			 * fix introduced by commit ac765f83f1397646
5491 			 * ("Btrfs: fix data corruption due to cloning of eof
5492 			 * block).
5493 			 *
5494 			 * So issue a clone of the aligned down range plus a
5495 			 * regular write for the eof block, if we hit that case.
5496 			 *
5497 			 * Also, we use the maximum possible sector size, 64K,
5498 			 * because we don't know what's the sector size of the
5499 			 * filesystem that receives the stream, so we have to
5500 			 * assume the largest possible sector size.
5501 			 */
5502 			if (src_end == clone_src_i_size &&
5503 			    !IS_ALIGNED(src_end, sectorsize) &&
5504 			    offset + clone_len < sctx->cur_inode_size) {
5505 				u64 slen;
5506 
5507 				slen = ALIGN_DOWN(src_end - clone_root->offset,
5508 						  sectorsize);
5509 				if (slen > 0) {
5510 					ret = send_clone(sctx, offset, slen,
5511 							 clone_root);
5512 					if (ret < 0)
5513 						goto out;
5514 				}
5515 				ret = send_extent_data(sctx, offset + slen,
5516 						       clone_len - slen);
5517 			} else {
5518 				ret = send_clone(sctx, offset, clone_len,
5519 						 clone_root);
5520 			}
5521 		} else if (crossed_src_i_size && clone_len < len) {
5522 			/*
5523 			 * If we are at i_size of the clone source inode and we
5524 			 * can not clone from it, terminate the loop. This is
5525 			 * to avoid sending two write operations, one with a
5526 			 * length matching clone_len and the final one after
5527 			 * this loop with a length of len - clone_len.
5528 			 *
5529 			 * When using encoded writes (BTRFS_SEND_FLAG_COMPRESSED
5530 			 * was passed to the send ioctl), this helps avoid
5531 			 * sending an encoded write for an offset that is not
5532 			 * sector size aligned, in case the i_size of the source
5533 			 * inode is not sector size aligned. That will make the
5534 			 * receiver fallback to decompression of the data and
5535 			 * writing it using regular buffered IO, therefore while
5536 			 * not incorrect, it's not optimal due decompression and
5537 			 * possible re-compression at the receiver.
5538 			 */
5539 			break;
5540 		} else {
5541 			ret = send_extent_data(sctx, offset, clone_len);
5542 		}
5543 
5544 		if (ret < 0)
5545 			goto out;
5546 
5547 		len -= clone_len;
5548 		if (len == 0)
5549 			break;
5550 		offset += clone_len;
5551 		clone_root->offset += clone_len;
5552 
5553 		/*
5554 		 * If we are cloning from the file we are currently processing,
5555 		 * and using the send root as the clone root, we must stop once
5556 		 * the current clone offset reaches the current eof of the file
5557 		 * at the receiver, otherwise we would issue an invalid clone
5558 		 * operation (source range going beyond eof) and cause the
5559 		 * receiver to fail. So if we reach the current eof, bail out
5560 		 * and fallback to a regular write.
5561 		 */
5562 		if (clone_root->root == sctx->send_root &&
5563 		    clone_root->ino == sctx->cur_ino &&
5564 		    clone_root->offset >= sctx->cur_inode_next_write_offset)
5565 			break;
5566 
5567 		data_offset += clone_len;
5568 next:
5569 		path->slots[0]++;
5570 	}
5571 
5572 	if (len > 0)
5573 		ret = send_extent_data(sctx, offset, len);
5574 	else
5575 		ret = 0;
5576 out:
5577 	btrfs_free_path(path);
5578 	return ret;
5579 }
5580 
send_write_or_clone(struct send_ctx * sctx,struct btrfs_path * path,struct btrfs_key * key,struct clone_root * clone_root)5581 static int send_write_or_clone(struct send_ctx *sctx,
5582 			       struct btrfs_path *path,
5583 			       struct btrfs_key *key,
5584 			       struct clone_root *clone_root)
5585 {
5586 	int ret = 0;
5587 	u64 offset = key->offset;
5588 	u64 end;
5589 	u64 bs = sctx->send_root->fs_info->sb->s_blocksize;
5590 
5591 	end = min_t(u64, btrfs_file_extent_end(path), sctx->cur_inode_size);
5592 	if (offset >= end)
5593 		return 0;
5594 
5595 	if (clone_root && IS_ALIGNED(end, bs)) {
5596 		struct btrfs_file_extent_item *ei;
5597 		u64 disk_byte;
5598 		u64 data_offset;
5599 
5600 		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
5601 				    struct btrfs_file_extent_item);
5602 		disk_byte = btrfs_file_extent_disk_bytenr(path->nodes[0], ei);
5603 		data_offset = btrfs_file_extent_offset(path->nodes[0], ei);
5604 		ret = clone_range(sctx, clone_root, disk_byte, data_offset,
5605 				  offset, end - offset);
5606 	} else {
5607 		ret = send_extent_data(sctx, offset, end - offset);
5608 	}
5609 	sctx->cur_inode_next_write_offset = end;
5610 	return ret;
5611 }
5612 
is_extent_unchanged(struct send_ctx * sctx,struct btrfs_path * left_path,struct btrfs_key * ekey)5613 static int is_extent_unchanged(struct send_ctx *sctx,
5614 			       struct btrfs_path *left_path,
5615 			       struct btrfs_key *ekey)
5616 {
5617 	int ret = 0;
5618 	struct btrfs_key key;
5619 	struct btrfs_path *path = NULL;
5620 	struct extent_buffer *eb;
5621 	int slot;
5622 	struct btrfs_key found_key;
5623 	struct btrfs_file_extent_item *ei;
5624 	u64 left_disknr;
5625 	u64 right_disknr;
5626 	u64 left_offset;
5627 	u64 right_offset;
5628 	u64 left_offset_fixed;
5629 	u64 left_len;
5630 	u64 right_len;
5631 	u64 left_gen;
5632 	u64 right_gen;
5633 	u8 left_type;
5634 	u8 right_type;
5635 
5636 	path = alloc_path_for_send();
5637 	if (!path)
5638 		return -ENOMEM;
5639 
5640 	eb = left_path->nodes[0];
5641 	slot = left_path->slots[0];
5642 	ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
5643 	left_type = btrfs_file_extent_type(eb, ei);
5644 
5645 	if (left_type != BTRFS_FILE_EXTENT_REG) {
5646 		ret = 0;
5647 		goto out;
5648 	}
5649 	left_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
5650 	left_len = btrfs_file_extent_num_bytes(eb, ei);
5651 	left_offset = btrfs_file_extent_offset(eb, ei);
5652 	left_gen = btrfs_file_extent_generation(eb, ei);
5653 
5654 	/*
5655 	 * Following comments will refer to these graphics. L is the left
5656 	 * extents which we are checking at the moment. 1-8 are the right
5657 	 * extents that we iterate.
5658 	 *
5659 	 *       |-----L-----|
5660 	 * |-1-|-2a-|-3-|-4-|-5-|-6-|
5661 	 *
5662 	 *       |-----L-----|
5663 	 * |--1--|-2b-|...(same as above)
5664 	 *
5665 	 * Alternative situation. Happens on files where extents got split.
5666 	 *       |-----L-----|
5667 	 * |-----------7-----------|-6-|
5668 	 *
5669 	 * Alternative situation. Happens on files which got larger.
5670 	 *       |-----L-----|
5671 	 * |-8-|
5672 	 * Nothing follows after 8.
5673 	 */
5674 
5675 	key.objectid = ekey->objectid;
5676 	key.type = BTRFS_EXTENT_DATA_KEY;
5677 	key.offset = ekey->offset;
5678 	ret = btrfs_search_slot_for_read(sctx->parent_root, &key, path, 0, 0);
5679 	if (ret < 0)
5680 		goto out;
5681 	if (ret) {
5682 		ret = 0;
5683 		goto out;
5684 	}
5685 
5686 	/*
5687 	 * Handle special case where the right side has no extents at all.
5688 	 */
5689 	eb = path->nodes[0];
5690 	slot = path->slots[0];
5691 	btrfs_item_key_to_cpu(eb, &found_key, slot);
5692 	if (found_key.objectid != key.objectid ||
5693 	    found_key.type != key.type) {
5694 		/* If we're a hole then just pretend nothing changed */
5695 		ret = (left_disknr) ? 0 : 1;
5696 		goto out;
5697 	}
5698 
5699 	/*
5700 	 * We're now on 2a, 2b or 7.
5701 	 */
5702 	key = found_key;
5703 	while (key.offset < ekey->offset + left_len) {
5704 		ei = btrfs_item_ptr(eb, slot, struct btrfs_file_extent_item);
5705 		right_type = btrfs_file_extent_type(eb, ei);
5706 		if (right_type != BTRFS_FILE_EXTENT_REG &&
5707 		    right_type != BTRFS_FILE_EXTENT_INLINE) {
5708 			ret = 0;
5709 			goto out;
5710 		}
5711 
5712 		if (right_type == BTRFS_FILE_EXTENT_INLINE) {
5713 			right_len = btrfs_file_extent_ram_bytes(eb, ei);
5714 			right_len = PAGE_ALIGN(right_len);
5715 		} else {
5716 			right_len = btrfs_file_extent_num_bytes(eb, ei);
5717 		}
5718 
5719 		/*
5720 		 * Are we at extent 8? If yes, we know the extent is changed.
5721 		 * This may only happen on the first iteration.
5722 		 */
5723 		if (found_key.offset + right_len <= ekey->offset) {
5724 			/* If we're a hole just pretend nothing changed */
5725 			ret = (left_disknr) ? 0 : 1;
5726 			goto out;
5727 		}
5728 
5729 		/*
5730 		 * We just wanted to see if when we have an inline extent, what
5731 		 * follows it is a regular extent (wanted to check the above
5732 		 * condition for inline extents too). This should normally not
5733 		 * happen but it's possible for example when we have an inline
5734 		 * compressed extent representing data with a size matching
5735 		 * the page size (currently the same as sector size).
5736 		 */
5737 		if (right_type == BTRFS_FILE_EXTENT_INLINE) {
5738 			ret = 0;
5739 			goto out;
5740 		}
5741 
5742 		right_disknr = btrfs_file_extent_disk_bytenr(eb, ei);
5743 		right_offset = btrfs_file_extent_offset(eb, ei);
5744 		right_gen = btrfs_file_extent_generation(eb, ei);
5745 
5746 		left_offset_fixed = left_offset;
5747 		if (key.offset < ekey->offset) {
5748 			/* Fix the right offset for 2a and 7. */
5749 			right_offset += ekey->offset - key.offset;
5750 		} else {
5751 			/* Fix the left offset for all behind 2a and 2b */
5752 			left_offset_fixed += key.offset - ekey->offset;
5753 		}
5754 
5755 		/*
5756 		 * Check if we have the same extent.
5757 		 */
5758 		if (left_disknr != right_disknr ||
5759 		    left_offset_fixed != right_offset ||
5760 		    left_gen != right_gen) {
5761 			ret = 0;
5762 			goto out;
5763 		}
5764 
5765 		/*
5766 		 * Go to the next extent.
5767 		 */
5768 		ret = btrfs_next_item(sctx->parent_root, path);
5769 		if (ret < 0)
5770 			goto out;
5771 		if (!ret) {
5772 			eb = path->nodes[0];
5773 			slot = path->slots[0];
5774 			btrfs_item_key_to_cpu(eb, &found_key, slot);
5775 		}
5776 		if (ret || found_key.objectid != key.objectid ||
5777 		    found_key.type != key.type) {
5778 			key.offset += right_len;
5779 			break;
5780 		}
5781 		if (found_key.offset != key.offset + right_len) {
5782 			ret = 0;
5783 			goto out;
5784 		}
5785 		key = found_key;
5786 	}
5787 
5788 	/*
5789 	 * We're now behind the left extent (treat as unchanged) or at the end
5790 	 * of the right side (treat as changed).
5791 	 */
5792 	if (key.offset >= ekey->offset + left_len)
5793 		ret = 1;
5794 	else
5795 		ret = 0;
5796 
5797 
5798 out:
5799 	btrfs_free_path(path);
5800 	return ret;
5801 }
5802 
get_last_extent(struct send_ctx * sctx,u64 offset)5803 static int get_last_extent(struct send_ctx *sctx, u64 offset)
5804 {
5805 	struct btrfs_path *path;
5806 	struct btrfs_root *root = sctx->send_root;
5807 	struct btrfs_key key;
5808 	int ret;
5809 
5810 	path = alloc_path_for_send();
5811 	if (!path)
5812 		return -ENOMEM;
5813 
5814 	sctx->cur_inode_last_extent = 0;
5815 
5816 	key.objectid = sctx->cur_ino;
5817 	key.type = BTRFS_EXTENT_DATA_KEY;
5818 	key.offset = offset;
5819 	ret = btrfs_search_slot_for_read(root, &key, path, 0, 1);
5820 	if (ret < 0)
5821 		goto out;
5822 	ret = 0;
5823 	btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
5824 	if (key.objectid != sctx->cur_ino || key.type != BTRFS_EXTENT_DATA_KEY)
5825 		goto out;
5826 
5827 	sctx->cur_inode_last_extent = btrfs_file_extent_end(path);
5828 out:
5829 	btrfs_free_path(path);
5830 	return ret;
5831 }
5832 
range_is_hole_in_parent(struct send_ctx * sctx,const u64 start,const u64 end)5833 static int range_is_hole_in_parent(struct send_ctx *sctx,
5834 				   const u64 start,
5835 				   const u64 end)
5836 {
5837 	struct btrfs_path *path;
5838 	struct btrfs_key key;
5839 	struct btrfs_root *root = sctx->parent_root;
5840 	u64 search_start = start;
5841 	int ret;
5842 
5843 	path = alloc_path_for_send();
5844 	if (!path)
5845 		return -ENOMEM;
5846 
5847 	key.objectid = sctx->cur_ino;
5848 	key.type = BTRFS_EXTENT_DATA_KEY;
5849 	key.offset = search_start;
5850 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5851 	if (ret < 0)
5852 		goto out;
5853 	if (ret > 0 && path->slots[0] > 0)
5854 		path->slots[0]--;
5855 
5856 	while (search_start < end) {
5857 		struct extent_buffer *leaf = path->nodes[0];
5858 		int slot = path->slots[0];
5859 		struct btrfs_file_extent_item *fi;
5860 		u64 extent_end;
5861 
5862 		if (slot >= btrfs_header_nritems(leaf)) {
5863 			ret = btrfs_next_leaf(root, path);
5864 			if (ret < 0)
5865 				goto out;
5866 			else if (ret > 0)
5867 				break;
5868 			continue;
5869 		}
5870 
5871 		btrfs_item_key_to_cpu(leaf, &key, slot);
5872 		if (key.objectid < sctx->cur_ino ||
5873 		    key.type < BTRFS_EXTENT_DATA_KEY)
5874 			goto next;
5875 		if (key.objectid > sctx->cur_ino ||
5876 		    key.type > BTRFS_EXTENT_DATA_KEY ||
5877 		    key.offset >= end)
5878 			break;
5879 
5880 		fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
5881 		extent_end = btrfs_file_extent_end(path);
5882 		if (extent_end <= start)
5883 			goto next;
5884 		if (btrfs_file_extent_disk_bytenr(leaf, fi) == 0) {
5885 			search_start = extent_end;
5886 			goto next;
5887 		}
5888 		ret = 0;
5889 		goto out;
5890 next:
5891 		path->slots[0]++;
5892 	}
5893 	ret = 1;
5894 out:
5895 	btrfs_free_path(path);
5896 	return ret;
5897 }
5898 
maybe_send_hole(struct send_ctx * sctx,struct btrfs_path * path,struct btrfs_key * key)5899 static int maybe_send_hole(struct send_ctx *sctx, struct btrfs_path *path,
5900 			   struct btrfs_key *key)
5901 {
5902 	int ret = 0;
5903 
5904 	if (sctx->cur_ino != key->objectid || !need_send_hole(sctx))
5905 		return 0;
5906 
5907 	if (sctx->cur_inode_last_extent == (u64)-1) {
5908 		ret = get_last_extent(sctx, key->offset - 1);
5909 		if (ret)
5910 			return ret;
5911 	}
5912 
5913 	if (path->slots[0] == 0 &&
5914 	    sctx->cur_inode_last_extent < key->offset) {
5915 		/*
5916 		 * We might have skipped entire leafs that contained only
5917 		 * file extent items for our current inode. These leafs have
5918 		 * a generation number smaller (older) than the one in the
5919 		 * current leaf and the leaf our last extent came from, and
5920 		 * are located between these 2 leafs.
5921 		 */
5922 		ret = get_last_extent(sctx, key->offset - 1);
5923 		if (ret)
5924 			return ret;
5925 	}
5926 
5927 	if (sctx->cur_inode_last_extent < key->offset) {
5928 		ret = range_is_hole_in_parent(sctx,
5929 					      sctx->cur_inode_last_extent,
5930 					      key->offset);
5931 		if (ret < 0)
5932 			return ret;
5933 		else if (ret == 0)
5934 			ret = send_hole(sctx, key->offset);
5935 		else
5936 			ret = 0;
5937 	}
5938 	sctx->cur_inode_last_extent = btrfs_file_extent_end(path);
5939 	return ret;
5940 }
5941 
process_extent(struct send_ctx * sctx,struct btrfs_path * path,struct btrfs_key * key)5942 static int process_extent(struct send_ctx *sctx,
5943 			  struct btrfs_path *path,
5944 			  struct btrfs_key *key)
5945 {
5946 	struct clone_root *found_clone = NULL;
5947 	int ret = 0;
5948 
5949 	if (S_ISLNK(sctx->cur_inode_mode))
5950 		return 0;
5951 
5952 	if (sctx->parent_root && !sctx->cur_inode_new) {
5953 		ret = is_extent_unchanged(sctx, path, key);
5954 		if (ret < 0)
5955 			goto out;
5956 		if (ret) {
5957 			ret = 0;
5958 			goto out_hole;
5959 		}
5960 	} else {
5961 		struct btrfs_file_extent_item *ei;
5962 		u8 type;
5963 
5964 		ei = btrfs_item_ptr(path->nodes[0], path->slots[0],
5965 				    struct btrfs_file_extent_item);
5966 		type = btrfs_file_extent_type(path->nodes[0], ei);
5967 		if (type == BTRFS_FILE_EXTENT_PREALLOC ||
5968 		    type == BTRFS_FILE_EXTENT_REG) {
5969 			/*
5970 			 * The send spec does not have a prealloc command yet,
5971 			 * so just leave a hole for prealloc'ed extents until
5972 			 * we have enough commands queued up to justify rev'ing
5973 			 * the send spec.
5974 			 */
5975 			if (type == BTRFS_FILE_EXTENT_PREALLOC) {
5976 				ret = 0;
5977 				goto out;
5978 			}
5979 
5980 			/* Have a hole, just skip it. */
5981 			if (btrfs_file_extent_disk_bytenr(path->nodes[0], ei) == 0) {
5982 				ret = 0;
5983 				goto out;
5984 			}
5985 		}
5986 	}
5987 
5988 	ret = find_extent_clone(sctx, path, key->objectid, key->offset,
5989 			sctx->cur_inode_size, &found_clone);
5990 	if (ret != -ENOENT && ret < 0)
5991 		goto out;
5992 
5993 	ret = send_write_or_clone(sctx, path, key, found_clone);
5994 	if (ret)
5995 		goto out;
5996 out_hole:
5997 	ret = maybe_send_hole(sctx, path, key);
5998 out:
5999 	return ret;
6000 }
6001 
process_all_extents(struct send_ctx * sctx)6002 static int process_all_extents(struct send_ctx *sctx)
6003 {
6004 	int ret;
6005 	struct btrfs_root *root;
6006 	struct btrfs_path *path;
6007 	struct btrfs_key key;
6008 	struct btrfs_key found_key;
6009 	struct extent_buffer *eb;
6010 	int slot;
6011 
6012 	root = sctx->send_root;
6013 	path = alloc_path_for_send();
6014 	if (!path)
6015 		return -ENOMEM;
6016 
6017 	key.objectid = sctx->cmp_key->objectid;
6018 	key.type = BTRFS_EXTENT_DATA_KEY;
6019 	key.offset = 0;
6020 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
6021 	if (ret < 0)
6022 		goto out;
6023 
6024 	while (1) {
6025 		eb = path->nodes[0];
6026 		slot = path->slots[0];
6027 
6028 		if (slot >= btrfs_header_nritems(eb)) {
6029 			ret = btrfs_next_leaf(root, path);
6030 			if (ret < 0) {
6031 				goto out;
6032 			} else if (ret > 0) {
6033 				ret = 0;
6034 				break;
6035 			}
6036 			continue;
6037 		}
6038 
6039 		btrfs_item_key_to_cpu(eb, &found_key, slot);
6040 
6041 		if (found_key.objectid != key.objectid ||
6042 		    found_key.type != key.type) {
6043 			ret = 0;
6044 			goto out;
6045 		}
6046 
6047 		ret = process_extent(sctx, path, &found_key);
6048 		if (ret < 0)
6049 			goto out;
6050 
6051 		path->slots[0]++;
6052 	}
6053 
6054 out:
6055 	btrfs_free_path(path);
6056 	return ret;
6057 }
6058 
process_recorded_refs_if_needed(struct send_ctx * sctx,int at_end,int * pending_move,int * refs_processed)6059 static int process_recorded_refs_if_needed(struct send_ctx *sctx, int at_end,
6060 					   int *pending_move,
6061 					   int *refs_processed)
6062 {
6063 	int ret = 0;
6064 
6065 	if (sctx->cur_ino == 0)
6066 		goto out;
6067 	if (!at_end && sctx->cur_ino == sctx->cmp_key->objectid &&
6068 	    sctx->cmp_key->type <= BTRFS_INODE_EXTREF_KEY)
6069 		goto out;
6070 	if (list_empty(&sctx->new_refs) && list_empty(&sctx->deleted_refs))
6071 		goto out;
6072 
6073 	ret = process_recorded_refs(sctx, pending_move);
6074 	if (ret < 0)
6075 		goto out;
6076 
6077 	*refs_processed = 1;
6078 out:
6079 	return ret;
6080 }
6081 
finish_inode_if_needed(struct send_ctx * sctx,int at_end)6082 static int finish_inode_if_needed(struct send_ctx *sctx, int at_end)
6083 {
6084 	int ret = 0;
6085 	u64 left_mode;
6086 	u64 left_uid;
6087 	u64 left_gid;
6088 	u64 right_mode;
6089 	u64 right_uid;
6090 	u64 right_gid;
6091 	int need_chmod = 0;
6092 	int need_chown = 0;
6093 	int need_truncate = 1;
6094 	int pending_move = 0;
6095 	int refs_processed = 0;
6096 
6097 	if (sctx->ignore_cur_inode)
6098 		return 0;
6099 
6100 	ret = process_recorded_refs_if_needed(sctx, at_end, &pending_move,
6101 					      &refs_processed);
6102 	if (ret < 0)
6103 		goto out;
6104 
6105 	/*
6106 	 * We have processed the refs and thus need to advance send_progress.
6107 	 * Now, calls to get_cur_xxx will take the updated refs of the current
6108 	 * inode into account.
6109 	 *
6110 	 * On the other hand, if our current inode is a directory and couldn't
6111 	 * be moved/renamed because its parent was renamed/moved too and it has
6112 	 * a higher inode number, we can only move/rename our current inode
6113 	 * after we moved/renamed its parent. Therefore in this case operate on
6114 	 * the old path (pre move/rename) of our current inode, and the
6115 	 * move/rename will be performed later.
6116 	 */
6117 	if (refs_processed && !pending_move)
6118 		sctx->send_progress = sctx->cur_ino + 1;
6119 
6120 	if (sctx->cur_ino == 0 || sctx->cur_inode_deleted)
6121 		goto out;
6122 	if (!at_end && sctx->cmp_key->objectid == sctx->cur_ino)
6123 		goto out;
6124 
6125 	ret = get_inode_info(sctx->send_root, sctx->cur_ino, NULL, NULL,
6126 			&left_mode, &left_uid, &left_gid, NULL);
6127 	if (ret < 0)
6128 		goto out;
6129 
6130 	if (!sctx->parent_root || sctx->cur_inode_new) {
6131 		need_chown = 1;
6132 		if (!S_ISLNK(sctx->cur_inode_mode))
6133 			need_chmod = 1;
6134 		if (sctx->cur_inode_next_write_offset == sctx->cur_inode_size)
6135 			need_truncate = 0;
6136 	} else {
6137 		u64 old_size;
6138 
6139 		ret = get_inode_info(sctx->parent_root, sctx->cur_ino,
6140 				&old_size, NULL, &right_mode, &right_uid,
6141 				&right_gid, NULL);
6142 		if (ret < 0)
6143 			goto out;
6144 
6145 		if (left_uid != right_uid || left_gid != right_gid)
6146 			need_chown = 1;
6147 		if (!S_ISLNK(sctx->cur_inode_mode) && left_mode != right_mode)
6148 			need_chmod = 1;
6149 		if ((old_size == sctx->cur_inode_size) ||
6150 		    (sctx->cur_inode_size > old_size &&
6151 		     sctx->cur_inode_next_write_offset == sctx->cur_inode_size))
6152 			need_truncate = 0;
6153 	}
6154 
6155 	if (S_ISREG(sctx->cur_inode_mode)) {
6156 		if (need_send_hole(sctx)) {
6157 			if (sctx->cur_inode_last_extent == (u64)-1 ||
6158 			    sctx->cur_inode_last_extent <
6159 			    sctx->cur_inode_size) {
6160 				ret = get_last_extent(sctx, (u64)-1);
6161 				if (ret)
6162 					goto out;
6163 			}
6164 			if (sctx->cur_inode_last_extent <
6165 			    sctx->cur_inode_size) {
6166 				ret = send_hole(sctx, sctx->cur_inode_size);
6167 				if (ret)
6168 					goto out;
6169 			}
6170 		}
6171 		if (need_truncate) {
6172 			ret = send_truncate(sctx, sctx->cur_ino,
6173 					    sctx->cur_inode_gen,
6174 					    sctx->cur_inode_size);
6175 			if (ret < 0)
6176 				goto out;
6177 		}
6178 	}
6179 
6180 	if (need_chown) {
6181 		ret = send_chown(sctx, sctx->cur_ino, sctx->cur_inode_gen,
6182 				left_uid, left_gid);
6183 		if (ret < 0)
6184 			goto out;
6185 	}
6186 	if (need_chmod) {
6187 		ret = send_chmod(sctx, sctx->cur_ino, sctx->cur_inode_gen,
6188 				left_mode);
6189 		if (ret < 0)
6190 			goto out;
6191 	}
6192 
6193 	ret = send_capabilities(sctx);
6194 	if (ret < 0)
6195 		goto out;
6196 
6197 	/*
6198 	 * If other directory inodes depended on our current directory
6199 	 * inode's move/rename, now do their move/rename operations.
6200 	 */
6201 	if (!is_waiting_for_move(sctx, sctx->cur_ino)) {
6202 		ret = apply_children_dir_moves(sctx);
6203 		if (ret)
6204 			goto out;
6205 		/*
6206 		 * Need to send that every time, no matter if it actually
6207 		 * changed between the two trees as we have done changes to
6208 		 * the inode before. If our inode is a directory and it's
6209 		 * waiting to be moved/renamed, we will send its utimes when
6210 		 * it's moved/renamed, therefore we don't need to do it here.
6211 		 */
6212 		sctx->send_progress = sctx->cur_ino + 1;
6213 		ret = send_utimes(sctx, sctx->cur_ino, sctx->cur_inode_gen);
6214 		if (ret < 0)
6215 			goto out;
6216 	}
6217 
6218 out:
6219 	return ret;
6220 }
6221 
6222 struct parent_paths_ctx {
6223 	struct list_head *refs;
6224 	struct send_ctx *sctx;
6225 };
6226 
record_parent_ref(int num,u64 dir,int index,struct fs_path * name,void * ctx)6227 static int record_parent_ref(int num, u64 dir, int index, struct fs_path *name,
6228 			     void *ctx)
6229 {
6230 	struct parent_paths_ctx *ppctx = ctx;
6231 
6232 	return record_ref(ppctx->sctx->parent_root, dir, name, ppctx->sctx,
6233 			  ppctx->refs);
6234 }
6235 
6236 /*
6237  * Issue unlink operations for all paths of the current inode found in the
6238  * parent snapshot.
6239  */
btrfs_unlink_all_paths(struct send_ctx * sctx)6240 static int btrfs_unlink_all_paths(struct send_ctx *sctx)
6241 {
6242 	LIST_HEAD(deleted_refs);
6243 	struct btrfs_path *path;
6244 	struct btrfs_key key;
6245 	struct parent_paths_ctx ctx;
6246 	int ret;
6247 
6248 	path = alloc_path_for_send();
6249 	if (!path)
6250 		return -ENOMEM;
6251 
6252 	key.objectid = sctx->cur_ino;
6253 	key.type = BTRFS_INODE_REF_KEY;
6254 	key.offset = 0;
6255 	ret = btrfs_search_slot(NULL, sctx->parent_root, &key, path, 0, 0);
6256 	if (ret < 0)
6257 		goto out;
6258 
6259 	ctx.refs = &deleted_refs;
6260 	ctx.sctx = sctx;
6261 
6262 	while (true) {
6263 		struct extent_buffer *eb = path->nodes[0];
6264 		int slot = path->slots[0];
6265 
6266 		if (slot >= btrfs_header_nritems(eb)) {
6267 			ret = btrfs_next_leaf(sctx->parent_root, path);
6268 			if (ret < 0)
6269 				goto out;
6270 			else if (ret > 0)
6271 				break;
6272 			continue;
6273 		}
6274 
6275 		btrfs_item_key_to_cpu(eb, &key, slot);
6276 		if (key.objectid != sctx->cur_ino)
6277 			break;
6278 		if (key.type != BTRFS_INODE_REF_KEY &&
6279 		    key.type != BTRFS_INODE_EXTREF_KEY)
6280 			break;
6281 
6282 		ret = iterate_inode_ref(sctx->parent_root, path, &key, 1,
6283 					record_parent_ref, &ctx);
6284 		if (ret < 0)
6285 			goto out;
6286 
6287 		path->slots[0]++;
6288 	}
6289 
6290 	while (!list_empty(&deleted_refs)) {
6291 		struct recorded_ref *ref;
6292 
6293 		ref = list_first_entry(&deleted_refs, struct recorded_ref, list);
6294 		ret = send_unlink(sctx, ref->full_path);
6295 		if (ret < 0)
6296 			goto out;
6297 		fs_path_free(ref->full_path);
6298 		list_del(&ref->list);
6299 		kfree(ref);
6300 	}
6301 	ret = 0;
6302 out:
6303 	btrfs_free_path(path);
6304 	if (ret)
6305 		__free_recorded_refs(&deleted_refs);
6306 	return ret;
6307 }
6308 
changed_inode(struct send_ctx * sctx,enum btrfs_compare_tree_result result)6309 static int changed_inode(struct send_ctx *sctx,
6310 			 enum btrfs_compare_tree_result result)
6311 {
6312 	int ret = 0;
6313 	struct btrfs_key *key = sctx->cmp_key;
6314 	struct btrfs_inode_item *left_ii = NULL;
6315 	struct btrfs_inode_item *right_ii = NULL;
6316 	u64 left_gen = 0;
6317 	u64 right_gen = 0;
6318 
6319 	sctx->cur_ino = key->objectid;
6320 	sctx->cur_inode_new_gen = 0;
6321 	sctx->cur_inode_last_extent = (u64)-1;
6322 	sctx->cur_inode_next_write_offset = 0;
6323 	sctx->ignore_cur_inode = false;
6324 
6325 	/*
6326 	 * Set send_progress to current inode. This will tell all get_cur_xxx
6327 	 * functions that the current inode's refs are not updated yet. Later,
6328 	 * when process_recorded_refs is finished, it is set to cur_ino + 1.
6329 	 */
6330 	sctx->send_progress = sctx->cur_ino;
6331 
6332 	if (result == BTRFS_COMPARE_TREE_NEW ||
6333 	    result == BTRFS_COMPARE_TREE_CHANGED) {
6334 		left_ii = btrfs_item_ptr(sctx->left_path->nodes[0],
6335 				sctx->left_path->slots[0],
6336 				struct btrfs_inode_item);
6337 		left_gen = btrfs_inode_generation(sctx->left_path->nodes[0],
6338 				left_ii);
6339 	} else {
6340 		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
6341 				sctx->right_path->slots[0],
6342 				struct btrfs_inode_item);
6343 		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
6344 				right_ii);
6345 	}
6346 	if (result == BTRFS_COMPARE_TREE_CHANGED) {
6347 		right_ii = btrfs_item_ptr(sctx->right_path->nodes[0],
6348 				sctx->right_path->slots[0],
6349 				struct btrfs_inode_item);
6350 
6351 		right_gen = btrfs_inode_generation(sctx->right_path->nodes[0],
6352 				right_ii);
6353 
6354 		/*
6355 		 * The cur_ino = root dir case is special here. We can't treat
6356 		 * the inode as deleted+reused because it would generate a
6357 		 * stream that tries to delete/mkdir the root dir.
6358 		 */
6359 		if (left_gen != right_gen &&
6360 		    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
6361 			sctx->cur_inode_new_gen = 1;
6362 	}
6363 
6364 	/*
6365 	 * Normally we do not find inodes with a link count of zero (orphans)
6366 	 * because the most common case is to create a snapshot and use it
6367 	 * for a send operation. However other less common use cases involve
6368 	 * using a subvolume and send it after turning it to RO mode just
6369 	 * after deleting all hard links of a file while holding an open
6370 	 * file descriptor against it or turning a RO snapshot into RW mode,
6371 	 * keep an open file descriptor against a file, delete it and then
6372 	 * turn the snapshot back to RO mode before using it for a send
6373 	 * operation. So if we find such cases, ignore the inode and all its
6374 	 * items completely if it's a new inode, or if it's a changed inode
6375 	 * make sure all its previous paths (from the parent snapshot) are all
6376 	 * unlinked and all other the inode items are ignored.
6377 	 */
6378 	if (result == BTRFS_COMPARE_TREE_NEW ||
6379 	    result == BTRFS_COMPARE_TREE_CHANGED) {
6380 		u32 nlinks;
6381 
6382 		nlinks = btrfs_inode_nlink(sctx->left_path->nodes[0], left_ii);
6383 		if (nlinks == 0) {
6384 			sctx->ignore_cur_inode = true;
6385 			if (result == BTRFS_COMPARE_TREE_CHANGED)
6386 				ret = btrfs_unlink_all_paths(sctx);
6387 			goto out;
6388 		}
6389 	}
6390 
6391 	if (result == BTRFS_COMPARE_TREE_NEW) {
6392 		sctx->cur_inode_gen = left_gen;
6393 		sctx->cur_inode_new = 1;
6394 		sctx->cur_inode_deleted = 0;
6395 		sctx->cur_inode_size = btrfs_inode_size(
6396 				sctx->left_path->nodes[0], left_ii);
6397 		sctx->cur_inode_mode = btrfs_inode_mode(
6398 				sctx->left_path->nodes[0], left_ii);
6399 		sctx->cur_inode_rdev = btrfs_inode_rdev(
6400 				sctx->left_path->nodes[0], left_ii);
6401 		if (sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID)
6402 			ret = send_create_inode_if_needed(sctx);
6403 	} else if (result == BTRFS_COMPARE_TREE_DELETED) {
6404 		sctx->cur_inode_gen = right_gen;
6405 		sctx->cur_inode_new = 0;
6406 		sctx->cur_inode_deleted = 1;
6407 		sctx->cur_inode_size = btrfs_inode_size(
6408 				sctx->right_path->nodes[0], right_ii);
6409 		sctx->cur_inode_mode = btrfs_inode_mode(
6410 				sctx->right_path->nodes[0], right_ii);
6411 	} else if (result == BTRFS_COMPARE_TREE_CHANGED) {
6412 		/*
6413 		 * We need to do some special handling in case the inode was
6414 		 * reported as changed with a changed generation number. This
6415 		 * means that the original inode was deleted and new inode
6416 		 * reused the same inum. So we have to treat the old inode as
6417 		 * deleted and the new one as new.
6418 		 */
6419 		if (sctx->cur_inode_new_gen) {
6420 			/*
6421 			 * First, process the inode as if it was deleted.
6422 			 */
6423 			sctx->cur_inode_gen = right_gen;
6424 			sctx->cur_inode_new = 0;
6425 			sctx->cur_inode_deleted = 1;
6426 			sctx->cur_inode_size = btrfs_inode_size(
6427 					sctx->right_path->nodes[0], right_ii);
6428 			sctx->cur_inode_mode = btrfs_inode_mode(
6429 					sctx->right_path->nodes[0], right_ii);
6430 			ret = process_all_refs(sctx,
6431 					BTRFS_COMPARE_TREE_DELETED);
6432 			if (ret < 0)
6433 				goto out;
6434 
6435 			/*
6436 			 * Now process the inode as if it was new.
6437 			 */
6438 			sctx->cur_inode_gen = left_gen;
6439 			sctx->cur_inode_new = 1;
6440 			sctx->cur_inode_deleted = 0;
6441 			sctx->cur_inode_size = btrfs_inode_size(
6442 					sctx->left_path->nodes[0], left_ii);
6443 			sctx->cur_inode_mode = btrfs_inode_mode(
6444 					sctx->left_path->nodes[0], left_ii);
6445 			sctx->cur_inode_rdev = btrfs_inode_rdev(
6446 					sctx->left_path->nodes[0], left_ii);
6447 			ret = send_create_inode_if_needed(sctx);
6448 			if (ret < 0)
6449 				goto out;
6450 
6451 			ret = process_all_refs(sctx, BTRFS_COMPARE_TREE_NEW);
6452 			if (ret < 0)
6453 				goto out;
6454 			/*
6455 			 * Advance send_progress now as we did not get into
6456 			 * process_recorded_refs_if_needed in the new_gen case.
6457 			 */
6458 			sctx->send_progress = sctx->cur_ino + 1;
6459 
6460 			/*
6461 			 * Now process all extents and xattrs of the inode as if
6462 			 * they were all new.
6463 			 */
6464 			ret = process_all_extents(sctx);
6465 			if (ret < 0)
6466 				goto out;
6467 			ret = process_all_new_xattrs(sctx);
6468 			if (ret < 0)
6469 				goto out;
6470 		} else {
6471 			sctx->cur_inode_gen = left_gen;
6472 			sctx->cur_inode_new = 0;
6473 			sctx->cur_inode_new_gen = 0;
6474 			sctx->cur_inode_deleted = 0;
6475 			sctx->cur_inode_size = btrfs_inode_size(
6476 					sctx->left_path->nodes[0], left_ii);
6477 			sctx->cur_inode_mode = btrfs_inode_mode(
6478 					sctx->left_path->nodes[0], left_ii);
6479 		}
6480 	}
6481 
6482 out:
6483 	return ret;
6484 }
6485 
6486 /*
6487  * We have to process new refs before deleted refs, but compare_trees gives us
6488  * the new and deleted refs mixed. To fix this, we record the new/deleted refs
6489  * first and later process them in process_recorded_refs.
6490  * For the cur_inode_new_gen case, we skip recording completely because
6491  * changed_inode did already initiate processing of refs. The reason for this is
6492  * that in this case, compare_tree actually compares the refs of 2 different
6493  * inodes. To fix this, process_all_refs is used in changed_inode to handle all
6494  * refs of the right tree as deleted and all refs of the left tree as new.
6495  */
changed_ref(struct send_ctx * sctx,enum btrfs_compare_tree_result result)6496 static int changed_ref(struct send_ctx *sctx,
6497 		       enum btrfs_compare_tree_result result)
6498 {
6499 	int ret = 0;
6500 
6501 	if (sctx->cur_ino != sctx->cmp_key->objectid) {
6502 		inconsistent_snapshot_error(sctx, result, "reference");
6503 		return -EIO;
6504 	}
6505 
6506 	if (!sctx->cur_inode_new_gen &&
6507 	    sctx->cur_ino != BTRFS_FIRST_FREE_OBJECTID) {
6508 		if (result == BTRFS_COMPARE_TREE_NEW)
6509 			ret = record_new_ref(sctx);
6510 		else if (result == BTRFS_COMPARE_TREE_DELETED)
6511 			ret = record_deleted_ref(sctx);
6512 		else if (result == BTRFS_COMPARE_TREE_CHANGED)
6513 			ret = record_changed_ref(sctx);
6514 	}
6515 
6516 	return ret;
6517 }
6518 
6519 /*
6520  * Process new/deleted/changed xattrs. We skip processing in the
6521  * cur_inode_new_gen case because changed_inode did already initiate processing
6522  * of xattrs. The reason is the same as in changed_ref
6523  */
changed_xattr(struct send_ctx * sctx,enum btrfs_compare_tree_result result)6524 static int changed_xattr(struct send_ctx *sctx,
6525 			 enum btrfs_compare_tree_result result)
6526 {
6527 	int ret = 0;
6528 
6529 	if (sctx->cur_ino != sctx->cmp_key->objectid) {
6530 		inconsistent_snapshot_error(sctx, result, "xattr");
6531 		return -EIO;
6532 	}
6533 
6534 	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
6535 		if (result == BTRFS_COMPARE_TREE_NEW)
6536 			ret = process_new_xattr(sctx);
6537 		else if (result == BTRFS_COMPARE_TREE_DELETED)
6538 			ret = process_deleted_xattr(sctx);
6539 		else if (result == BTRFS_COMPARE_TREE_CHANGED)
6540 			ret = process_changed_xattr(sctx);
6541 	}
6542 
6543 	return ret;
6544 }
6545 
6546 /*
6547  * Process new/deleted/changed extents. We skip processing in the
6548  * cur_inode_new_gen case because changed_inode did already initiate processing
6549  * of extents. The reason is the same as in changed_ref
6550  */
changed_extent(struct send_ctx * sctx,enum btrfs_compare_tree_result result)6551 static int changed_extent(struct send_ctx *sctx,
6552 			  enum btrfs_compare_tree_result result)
6553 {
6554 	int ret = 0;
6555 
6556 	/*
6557 	 * We have found an extent item that changed without the inode item
6558 	 * having changed. This can happen either after relocation (where the
6559 	 * disk_bytenr of an extent item is replaced at
6560 	 * relocation.c:replace_file_extents()) or after deduplication into a
6561 	 * file in both the parent and send snapshots (where an extent item can
6562 	 * get modified or replaced with a new one). Note that deduplication
6563 	 * updates the inode item, but it only changes the iversion (sequence
6564 	 * field in the inode item) of the inode, so if a file is deduplicated
6565 	 * the same amount of times in both the parent and send snapshots, its
6566 	 * iversion becomes the same in both snapshots, whence the inode item is
6567 	 * the same on both snapshots.
6568 	 */
6569 	if (sctx->cur_ino != sctx->cmp_key->objectid)
6570 		return 0;
6571 
6572 	if (!sctx->cur_inode_new_gen && !sctx->cur_inode_deleted) {
6573 		if (result != BTRFS_COMPARE_TREE_DELETED)
6574 			ret = process_extent(sctx, sctx->left_path,
6575 					sctx->cmp_key);
6576 	}
6577 
6578 	return ret;
6579 }
6580 
dir_changed(struct send_ctx * sctx,u64 dir)6581 static int dir_changed(struct send_ctx *sctx, u64 dir)
6582 {
6583 	u64 orig_gen, new_gen;
6584 	int ret;
6585 
6586 	ret = get_inode_info(sctx->send_root, dir, NULL, &new_gen, NULL, NULL,
6587 			     NULL, NULL);
6588 	if (ret)
6589 		return ret;
6590 
6591 	ret = get_inode_info(sctx->parent_root, dir, NULL, &orig_gen, NULL,
6592 			     NULL, NULL, NULL);
6593 	if (ret)
6594 		return ret;
6595 
6596 	return (orig_gen != new_gen) ? 1 : 0;
6597 }
6598 
compare_refs(struct send_ctx * sctx,struct btrfs_path * path,struct btrfs_key * key)6599 static int compare_refs(struct send_ctx *sctx, struct btrfs_path *path,
6600 			struct btrfs_key *key)
6601 {
6602 	struct btrfs_inode_extref *extref;
6603 	struct extent_buffer *leaf;
6604 	u64 dirid = 0, last_dirid = 0;
6605 	unsigned long ptr;
6606 	u32 item_size;
6607 	u32 cur_offset = 0;
6608 	int ref_name_len;
6609 	int ret = 0;
6610 
6611 	/* Easy case, just check this one dirid */
6612 	if (key->type == BTRFS_INODE_REF_KEY) {
6613 		dirid = key->offset;
6614 
6615 		ret = dir_changed(sctx, dirid);
6616 		goto out;
6617 	}
6618 
6619 	leaf = path->nodes[0];
6620 	item_size = btrfs_item_size_nr(leaf, path->slots[0]);
6621 	ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
6622 	while (cur_offset < item_size) {
6623 		extref = (struct btrfs_inode_extref *)(ptr +
6624 						       cur_offset);
6625 		dirid = btrfs_inode_extref_parent(leaf, extref);
6626 		ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
6627 		cur_offset += ref_name_len + sizeof(*extref);
6628 		if (dirid == last_dirid)
6629 			continue;
6630 		ret = dir_changed(sctx, dirid);
6631 		if (ret)
6632 			break;
6633 		last_dirid = dirid;
6634 	}
6635 out:
6636 	return ret;
6637 }
6638 
6639 /*
6640  * Updates compare related fields in sctx and simply forwards to the actual
6641  * changed_xxx functions.
6642  */
changed_cb(struct btrfs_path * left_path,struct btrfs_path * right_path,struct btrfs_key * key,enum btrfs_compare_tree_result result,struct send_ctx * sctx)6643 static int changed_cb(struct btrfs_path *left_path,
6644 		      struct btrfs_path *right_path,
6645 		      struct btrfs_key *key,
6646 		      enum btrfs_compare_tree_result result,
6647 		      struct send_ctx *sctx)
6648 {
6649 	int ret = 0;
6650 
6651 	/*
6652 	 * We can not hold the commit root semaphore here. This is because in
6653 	 * the case of sending and receiving to the same filesystem, using a
6654 	 * pipe, could result in a deadlock:
6655 	 *
6656 	 * 1) The task running send blocks on the pipe because it's full;
6657 	 *
6658 	 * 2) The task running receive, which is the only consumer of the pipe,
6659 	 *    is waiting for a transaction commit (for example due to a space
6660 	 *    reservation when doing a write or triggering a transaction commit
6661 	 *    when creating a subvolume);
6662 	 *
6663 	 * 3) The transaction is waiting to write lock the commit root semaphore,
6664 	 *    but can not acquire it since it's being held at 1).
6665 	 *
6666 	 * Down this call chain we write to the pipe through kernel_write().
6667 	 * The same type of problem can also happen when sending to a file that
6668 	 * is stored in the same filesystem - when reserving space for a write
6669 	 * into the file, we can trigger a transaction commit.
6670 	 *
6671 	 * Our caller has supplied us with clones of leaves from the send and
6672 	 * parent roots, so we're safe here from a concurrent relocation and
6673 	 * further reallocation of metadata extents while we are here. Below we
6674 	 * also assert that the leaves are clones.
6675 	 */
6676 	lockdep_assert_not_held(&sctx->send_root->fs_info->commit_root_sem);
6677 
6678 	/*
6679 	 * We always have a send root, so left_path is never NULL. We will not
6680 	 * have a leaf when we have reached the end of the send root but have
6681 	 * not yet reached the end of the parent root.
6682 	 */
6683 	if (left_path->nodes[0])
6684 		ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
6685 				&left_path->nodes[0]->bflags));
6686 	/*
6687 	 * When doing a full send we don't have a parent root, so right_path is
6688 	 * NULL. When doing an incremental send, we may have reached the end of
6689 	 * the parent root already, so we don't have a leaf at right_path.
6690 	 */
6691 	if (right_path && right_path->nodes[0])
6692 		ASSERT(test_bit(EXTENT_BUFFER_UNMAPPED,
6693 				&right_path->nodes[0]->bflags));
6694 
6695 	if (result == BTRFS_COMPARE_TREE_SAME) {
6696 		if (key->type == BTRFS_INODE_REF_KEY ||
6697 		    key->type == BTRFS_INODE_EXTREF_KEY) {
6698 			ret = compare_refs(sctx, left_path, key);
6699 			if (!ret)
6700 				return 0;
6701 			if (ret < 0)
6702 				return ret;
6703 		} else if (key->type == BTRFS_EXTENT_DATA_KEY) {
6704 			return maybe_send_hole(sctx, left_path, key);
6705 		} else {
6706 			return 0;
6707 		}
6708 		result = BTRFS_COMPARE_TREE_CHANGED;
6709 		ret = 0;
6710 	}
6711 
6712 	sctx->left_path = left_path;
6713 	sctx->right_path = right_path;
6714 	sctx->cmp_key = key;
6715 
6716 	ret = finish_inode_if_needed(sctx, 0);
6717 	if (ret < 0)
6718 		goto out;
6719 
6720 	/* Ignore non-FS objects */
6721 	if (key->objectid == BTRFS_FREE_INO_OBJECTID ||
6722 	    key->objectid == BTRFS_FREE_SPACE_OBJECTID)
6723 		goto out;
6724 
6725 	if (key->type == BTRFS_INODE_ITEM_KEY) {
6726 		ret = changed_inode(sctx, result);
6727 	} else if (!sctx->ignore_cur_inode) {
6728 		if (key->type == BTRFS_INODE_REF_KEY ||
6729 		    key->type == BTRFS_INODE_EXTREF_KEY)
6730 			ret = changed_ref(sctx, result);
6731 		else if (key->type == BTRFS_XATTR_ITEM_KEY)
6732 			ret = changed_xattr(sctx, result);
6733 		else if (key->type == BTRFS_EXTENT_DATA_KEY)
6734 			ret = changed_extent(sctx, result);
6735 	}
6736 
6737 out:
6738 	return ret;
6739 }
6740 
search_key_again(const struct send_ctx * sctx,struct btrfs_root * root,struct btrfs_path * path,const struct btrfs_key * key)6741 static int search_key_again(const struct send_ctx *sctx,
6742 			    struct btrfs_root *root,
6743 			    struct btrfs_path *path,
6744 			    const struct btrfs_key *key)
6745 {
6746 	int ret;
6747 
6748 	if (!path->need_commit_sem)
6749 		lockdep_assert_held_read(&root->fs_info->commit_root_sem);
6750 
6751 	/*
6752 	 * Roots used for send operations are readonly and no one can add,
6753 	 * update or remove keys from them, so we should be able to find our
6754 	 * key again. The only exception is deduplication, which can operate on
6755 	 * readonly roots and add, update or remove keys to/from them - but at
6756 	 * the moment we don't allow it to run in parallel with send.
6757 	 */
6758 	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
6759 	ASSERT(ret <= 0);
6760 	if (ret > 0) {
6761 		btrfs_print_tree(path->nodes[path->lowest_level], false);
6762 		btrfs_err(root->fs_info,
6763 "send: key (%llu %u %llu) not found in %s root %llu, lowest_level %d, slot %d",
6764 			  key->objectid, key->type, key->offset,
6765 			  (root == sctx->parent_root ? "parent" : "send"),
6766 			  root->root_key.objectid, path->lowest_level,
6767 			  path->slots[path->lowest_level]);
6768 		return -EUCLEAN;
6769 	}
6770 
6771 	return ret;
6772 }
6773 
full_send_tree(struct send_ctx * sctx)6774 static int full_send_tree(struct send_ctx *sctx)
6775 {
6776 	int ret;
6777 	struct btrfs_root *send_root = sctx->send_root;
6778 	struct btrfs_key key;
6779 	struct btrfs_fs_info *fs_info = send_root->fs_info;
6780 	struct btrfs_path *path;
6781 
6782 	path = alloc_path_for_send();
6783 	if (!path)
6784 		return -ENOMEM;
6785 	path->reada = READA_FORWARD_ALWAYS;
6786 
6787 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
6788 	key.type = BTRFS_INODE_ITEM_KEY;
6789 	key.offset = 0;
6790 
6791 	down_read(&fs_info->commit_root_sem);
6792 	sctx->last_reloc_trans = fs_info->last_reloc_trans;
6793 	up_read(&fs_info->commit_root_sem);
6794 
6795 	ret = btrfs_search_slot_for_read(send_root, &key, path, 1, 0);
6796 	if (ret < 0)
6797 		goto out;
6798 	if (ret)
6799 		goto out_finish;
6800 
6801 	while (1) {
6802 		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
6803 
6804 		ret = changed_cb(path, NULL, &key,
6805 				 BTRFS_COMPARE_TREE_NEW, sctx);
6806 		if (ret < 0)
6807 			goto out;
6808 
6809 		down_read(&fs_info->commit_root_sem);
6810 		if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
6811 			sctx->last_reloc_trans = fs_info->last_reloc_trans;
6812 			up_read(&fs_info->commit_root_sem);
6813 			/*
6814 			 * A transaction used for relocating a block group was
6815 			 * committed or is about to finish its commit. Release
6816 			 * our path (leaf) and restart the search, so that we
6817 			 * avoid operating on any file extent items that are
6818 			 * stale, with a disk_bytenr that reflects a pre
6819 			 * relocation value. This way we avoid as much as
6820 			 * possible to fallback to regular writes when checking
6821 			 * if we can clone file ranges.
6822 			 */
6823 			btrfs_release_path(path);
6824 			ret = search_key_again(sctx, send_root, path, &key);
6825 			if (ret < 0)
6826 				goto out;
6827 		} else {
6828 			up_read(&fs_info->commit_root_sem);
6829 		}
6830 
6831 		ret = btrfs_next_item(send_root, path);
6832 		if (ret < 0)
6833 			goto out;
6834 		if (ret) {
6835 			ret  = 0;
6836 			break;
6837 		}
6838 	}
6839 
6840 out_finish:
6841 	ret = finish_inode_if_needed(sctx, 1);
6842 
6843 out:
6844 	btrfs_free_path(path);
6845 	return ret;
6846 }
6847 
replace_node_with_clone(struct btrfs_path * path,int level)6848 static int replace_node_with_clone(struct btrfs_path *path, int level)
6849 {
6850 	struct extent_buffer *clone;
6851 
6852 	clone = btrfs_clone_extent_buffer(path->nodes[level]);
6853 	if (!clone)
6854 		return -ENOMEM;
6855 
6856 	free_extent_buffer(path->nodes[level]);
6857 	path->nodes[level] = clone;
6858 
6859 	return 0;
6860 }
6861 
tree_move_down(struct btrfs_path * path,int * level,u64 reada_min_gen)6862 static int tree_move_down(struct btrfs_path *path, int *level, u64 reada_min_gen)
6863 {
6864 	struct extent_buffer *eb;
6865 	struct extent_buffer *parent = path->nodes[*level];
6866 	int slot = path->slots[*level];
6867 	const int nritems = btrfs_header_nritems(parent);
6868 	u64 reada_max;
6869 	u64 reada_done = 0;
6870 
6871 	lockdep_assert_held_read(&parent->fs_info->commit_root_sem);
6872 
6873 	BUG_ON(*level == 0);
6874 	eb = btrfs_read_node_slot(parent, slot);
6875 	if (IS_ERR(eb))
6876 		return PTR_ERR(eb);
6877 
6878 	/*
6879 	 * Trigger readahead for the next leaves we will process, so that it is
6880 	 * very likely that when we need them they are already in memory and we
6881 	 * will not block on disk IO. For nodes we only do readahead for one,
6882 	 * since the time window between processing nodes is typically larger.
6883 	 */
6884 	reada_max = (*level == 1 ? SZ_128K : eb->fs_info->nodesize);
6885 
6886 	for (slot++; slot < nritems && reada_done < reada_max; slot++) {
6887 		if (btrfs_node_ptr_generation(parent, slot) > reada_min_gen) {
6888 			btrfs_readahead_node_child(parent, slot);
6889 			reada_done += eb->fs_info->nodesize;
6890 		}
6891 	}
6892 
6893 	path->nodes[*level - 1] = eb;
6894 	path->slots[*level - 1] = 0;
6895 	(*level)--;
6896 
6897 	if (*level == 0)
6898 		return replace_node_with_clone(path, 0);
6899 
6900 	return 0;
6901 }
6902 
tree_move_next_or_upnext(struct btrfs_path * path,int * level,int root_level)6903 static int tree_move_next_or_upnext(struct btrfs_path *path,
6904 				    int *level, int root_level)
6905 {
6906 	int ret = 0;
6907 	int nritems;
6908 	nritems = btrfs_header_nritems(path->nodes[*level]);
6909 
6910 	path->slots[*level]++;
6911 
6912 	while (path->slots[*level] >= nritems) {
6913 		if (*level == root_level) {
6914 			path->slots[*level] = nritems - 1;
6915 			return -1;
6916 		}
6917 
6918 		/* move upnext */
6919 		path->slots[*level] = 0;
6920 		free_extent_buffer(path->nodes[*level]);
6921 		path->nodes[*level] = NULL;
6922 		(*level)++;
6923 		path->slots[*level]++;
6924 
6925 		nritems = btrfs_header_nritems(path->nodes[*level]);
6926 		ret = 1;
6927 	}
6928 	return ret;
6929 }
6930 
6931 /*
6932  * Returns 1 if it had to move up and next. 0 is returned if it moved only next
6933  * or down.
6934  */
tree_advance(struct btrfs_path * path,int * level,int root_level,int allow_down,struct btrfs_key * key,u64 reada_min_gen)6935 static int tree_advance(struct btrfs_path *path,
6936 			int *level, int root_level,
6937 			int allow_down,
6938 			struct btrfs_key *key,
6939 			u64 reada_min_gen)
6940 {
6941 	int ret;
6942 
6943 	if (*level == 0 || !allow_down) {
6944 		ret = tree_move_next_or_upnext(path, level, root_level);
6945 	} else {
6946 		ret = tree_move_down(path, level, reada_min_gen);
6947 	}
6948 
6949 	/*
6950 	 * Even if we have reached the end of a tree, ret is -1, update the key
6951 	 * anyway, so that in case we need to restart due to a block group
6952 	 * relocation, we can assert that the last key of the root node still
6953 	 * exists in the tree.
6954 	 */
6955 	if (*level == 0)
6956 		btrfs_item_key_to_cpu(path->nodes[*level], key,
6957 				      path->slots[*level]);
6958 	else
6959 		btrfs_node_key_to_cpu(path->nodes[*level], key,
6960 				      path->slots[*level]);
6961 
6962 	return ret;
6963 }
6964 
tree_compare_item(struct btrfs_path * left_path,struct btrfs_path * right_path,char * tmp_buf)6965 static int tree_compare_item(struct btrfs_path *left_path,
6966 			     struct btrfs_path *right_path,
6967 			     char *tmp_buf)
6968 {
6969 	int cmp;
6970 	int len1, len2;
6971 	unsigned long off1, off2;
6972 
6973 	len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
6974 	len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
6975 	if (len1 != len2)
6976 		return 1;
6977 
6978 	off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
6979 	off2 = btrfs_item_ptr_offset(right_path->nodes[0],
6980 				right_path->slots[0]);
6981 
6982 	read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
6983 
6984 	cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
6985 	if (cmp)
6986 		return 1;
6987 	return 0;
6988 }
6989 
6990 /*
6991  * A transaction used for relocating a block group was committed or is about to
6992  * finish its commit. Release our paths and restart the search, so that we are
6993  * not using stale extent buffers:
6994  *
6995  * 1) For levels > 0, we are only holding references of extent buffers, without
6996  *    any locks on them, which does not prevent them from having been relocated
6997  *    and reallocated after the last time we released the commit root semaphore.
6998  *    The exception are the root nodes, for which we always have a clone, see
6999  *    the comment at btrfs_compare_trees();
7000  *
7001  * 2) For leaves, level 0, we are holding copies (clones) of extent buffers, so
7002  *    we are safe from the concurrent relocation and reallocation. However they
7003  *    can have file extent items with a pre relocation disk_bytenr value, so we
7004  *    restart the start from the current commit roots and clone the new leaves so
7005  *    that we get the post relocation disk_bytenr values. Not doing so, could
7006  *    make us clone the wrong data in case there are new extents using the old
7007  *    disk_bytenr that happen to be shared.
7008  */
restart_after_relocation(struct btrfs_path * left_path,struct btrfs_path * right_path,const struct btrfs_key * left_key,const struct btrfs_key * right_key,int left_level,int right_level,const struct send_ctx * sctx)7009 static int restart_after_relocation(struct btrfs_path *left_path,
7010 				    struct btrfs_path *right_path,
7011 				    const struct btrfs_key *left_key,
7012 				    const struct btrfs_key *right_key,
7013 				    int left_level,
7014 				    int right_level,
7015 				    const struct send_ctx *sctx)
7016 {
7017 	int root_level;
7018 	int ret;
7019 
7020 	lockdep_assert_held_read(&sctx->send_root->fs_info->commit_root_sem);
7021 
7022 	btrfs_release_path(left_path);
7023 	btrfs_release_path(right_path);
7024 
7025 	/*
7026 	 * Since keys can not be added or removed to/from our roots because they
7027 	 * are readonly and we do not allow deduplication to run in parallel
7028 	 * (which can add, remove or change keys), the layout of the trees should
7029 	 * not change.
7030 	 */
7031 	left_path->lowest_level = left_level;
7032 	ret = search_key_again(sctx, sctx->send_root, left_path, left_key);
7033 	if (ret < 0)
7034 		return ret;
7035 
7036 	right_path->lowest_level = right_level;
7037 	ret = search_key_again(sctx, sctx->parent_root, right_path, right_key);
7038 	if (ret < 0)
7039 		return ret;
7040 
7041 	/*
7042 	 * If the lowest level nodes are leaves, clone them so that they can be
7043 	 * safely used by changed_cb() while not under the protection of the
7044 	 * commit root semaphore, even if relocation and reallocation happens in
7045 	 * parallel.
7046 	 */
7047 	if (left_level == 0) {
7048 		ret = replace_node_with_clone(left_path, 0);
7049 		if (ret < 0)
7050 			return ret;
7051 	}
7052 
7053 	if (right_level == 0) {
7054 		ret = replace_node_with_clone(right_path, 0);
7055 		if (ret < 0)
7056 			return ret;
7057 	}
7058 
7059 	/*
7060 	 * Now clone the root nodes (unless they happen to be the leaves we have
7061 	 * already cloned). This is to protect against concurrent snapshotting of
7062 	 * the send and parent roots (see the comment at btrfs_compare_trees()).
7063 	 */
7064 	root_level = btrfs_header_level(sctx->send_root->commit_root);
7065 	if (root_level > 0) {
7066 		ret = replace_node_with_clone(left_path, root_level);
7067 		if (ret < 0)
7068 			return ret;
7069 	}
7070 
7071 	root_level = btrfs_header_level(sctx->parent_root->commit_root);
7072 	if (root_level > 0) {
7073 		ret = replace_node_with_clone(right_path, root_level);
7074 		if (ret < 0)
7075 			return ret;
7076 	}
7077 
7078 	return 0;
7079 }
7080 
7081 /*
7082  * This function compares two trees and calls the provided callback for
7083  * every changed/new/deleted item it finds.
7084  * If shared tree blocks are encountered, whole subtrees are skipped, making
7085  * the compare pretty fast on snapshotted subvolumes.
7086  *
7087  * This currently works on commit roots only. As commit roots are read only,
7088  * we don't do any locking. The commit roots are protected with transactions.
7089  * Transactions are ended and rejoined when a commit is tried in between.
7090  *
7091  * This function checks for modifications done to the trees while comparing.
7092  * If it detects a change, it aborts immediately.
7093  */
btrfs_compare_trees(struct btrfs_root * left_root,struct btrfs_root * right_root,struct send_ctx * sctx)7094 static int btrfs_compare_trees(struct btrfs_root *left_root,
7095 			struct btrfs_root *right_root, struct send_ctx *sctx)
7096 {
7097 	struct btrfs_fs_info *fs_info = left_root->fs_info;
7098 	int ret;
7099 	int cmp;
7100 	struct btrfs_path *left_path = NULL;
7101 	struct btrfs_path *right_path = NULL;
7102 	struct btrfs_key left_key;
7103 	struct btrfs_key right_key;
7104 	char *tmp_buf = NULL;
7105 	int left_root_level;
7106 	int right_root_level;
7107 	int left_level;
7108 	int right_level;
7109 	int left_end_reached = 0;
7110 	int right_end_reached = 0;
7111 	int advance_left = 0;
7112 	int advance_right = 0;
7113 	u64 left_blockptr;
7114 	u64 right_blockptr;
7115 	u64 left_gen;
7116 	u64 right_gen;
7117 	u64 reada_min_gen;
7118 
7119 	left_path = btrfs_alloc_path();
7120 	if (!left_path) {
7121 		ret = -ENOMEM;
7122 		goto out;
7123 	}
7124 	right_path = btrfs_alloc_path();
7125 	if (!right_path) {
7126 		ret = -ENOMEM;
7127 		goto out;
7128 	}
7129 
7130 	tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
7131 	if (!tmp_buf) {
7132 		ret = -ENOMEM;
7133 		goto out;
7134 	}
7135 
7136 	left_path->search_commit_root = 1;
7137 	left_path->skip_locking = 1;
7138 	right_path->search_commit_root = 1;
7139 	right_path->skip_locking = 1;
7140 
7141 	/*
7142 	 * Strategy: Go to the first items of both trees. Then do
7143 	 *
7144 	 * If both trees are at level 0
7145 	 *   Compare keys of current items
7146 	 *     If left < right treat left item as new, advance left tree
7147 	 *       and repeat
7148 	 *     If left > right treat right item as deleted, advance right tree
7149 	 *       and repeat
7150 	 *     If left == right do deep compare of items, treat as changed if
7151 	 *       needed, advance both trees and repeat
7152 	 * If both trees are at the same level but not at level 0
7153 	 *   Compare keys of current nodes/leafs
7154 	 *     If left < right advance left tree and repeat
7155 	 *     If left > right advance right tree and repeat
7156 	 *     If left == right compare blockptrs of the next nodes/leafs
7157 	 *       If they match advance both trees but stay at the same level
7158 	 *         and repeat
7159 	 *       If they don't match advance both trees while allowing to go
7160 	 *         deeper and repeat
7161 	 * If tree levels are different
7162 	 *   Advance the tree that needs it and repeat
7163 	 *
7164 	 * Advancing a tree means:
7165 	 *   If we are at level 0, try to go to the next slot. If that's not
7166 	 *   possible, go one level up and repeat. Stop when we found a level
7167 	 *   where we could go to the next slot. We may at this point be on a
7168 	 *   node or a leaf.
7169 	 *
7170 	 *   If we are not at level 0 and not on shared tree blocks, go one
7171 	 *   level deeper.
7172 	 *
7173 	 *   If we are not at level 0 and on shared tree blocks, go one slot to
7174 	 *   the right if possible or go up and right.
7175 	 */
7176 
7177 	down_read(&fs_info->commit_root_sem);
7178 	left_level = btrfs_header_level(left_root->commit_root);
7179 	left_root_level = left_level;
7180 	/*
7181 	 * We clone the root node of the send and parent roots to prevent races
7182 	 * with snapshot creation of these roots. Snapshot creation COWs the
7183 	 * root node of a tree, so after the transaction is committed the old
7184 	 * extent can be reallocated while this send operation is still ongoing.
7185 	 * So we clone them, under the commit root semaphore, to be race free.
7186 	 */
7187 	left_path->nodes[left_level] =
7188 			btrfs_clone_extent_buffer(left_root->commit_root);
7189 	if (!left_path->nodes[left_level]) {
7190 		ret = -ENOMEM;
7191 		goto out_unlock;
7192 	}
7193 
7194 	right_level = btrfs_header_level(right_root->commit_root);
7195 	right_root_level = right_level;
7196 	right_path->nodes[right_level] =
7197 			btrfs_clone_extent_buffer(right_root->commit_root);
7198 	if (!right_path->nodes[right_level]) {
7199 		ret = -ENOMEM;
7200 		goto out_unlock;
7201 	}
7202 	/*
7203 	 * Our right root is the parent root, while the left root is the "send"
7204 	 * root. We know that all new nodes/leaves in the left root must have
7205 	 * a generation greater than the right root's generation, so we trigger
7206 	 * readahead for those nodes and leaves of the left root, as we know we
7207 	 * will need to read them at some point.
7208 	 */
7209 	reada_min_gen = btrfs_header_generation(right_root->commit_root);
7210 
7211 	if (left_level == 0)
7212 		btrfs_item_key_to_cpu(left_path->nodes[left_level],
7213 				&left_key, left_path->slots[left_level]);
7214 	else
7215 		btrfs_node_key_to_cpu(left_path->nodes[left_level],
7216 				&left_key, left_path->slots[left_level]);
7217 	if (right_level == 0)
7218 		btrfs_item_key_to_cpu(right_path->nodes[right_level],
7219 				&right_key, right_path->slots[right_level]);
7220 	else
7221 		btrfs_node_key_to_cpu(right_path->nodes[right_level],
7222 				&right_key, right_path->slots[right_level]);
7223 
7224 	sctx->last_reloc_trans = fs_info->last_reloc_trans;
7225 
7226 	while (1) {
7227 		if (need_resched() ||
7228 		    rwsem_is_contended(&fs_info->commit_root_sem)) {
7229 			up_read(&fs_info->commit_root_sem);
7230 			cond_resched();
7231 			down_read(&fs_info->commit_root_sem);
7232 		}
7233 
7234 		if (fs_info->last_reloc_trans > sctx->last_reloc_trans) {
7235 			ret = restart_after_relocation(left_path, right_path,
7236 						       &left_key, &right_key,
7237 						       left_level, right_level,
7238 						       sctx);
7239 			if (ret < 0)
7240 				goto out_unlock;
7241 			sctx->last_reloc_trans = fs_info->last_reloc_trans;
7242 		}
7243 
7244 		if (advance_left && !left_end_reached) {
7245 			ret = tree_advance(left_path, &left_level,
7246 					left_root_level,
7247 					advance_left != ADVANCE_ONLY_NEXT,
7248 					&left_key, reada_min_gen);
7249 			if (ret == -1)
7250 				left_end_reached = ADVANCE;
7251 			else if (ret < 0)
7252 				goto out_unlock;
7253 			advance_left = 0;
7254 		}
7255 		if (advance_right && !right_end_reached) {
7256 			ret = tree_advance(right_path, &right_level,
7257 					right_root_level,
7258 					advance_right != ADVANCE_ONLY_NEXT,
7259 					&right_key, reada_min_gen);
7260 			if (ret == -1)
7261 				right_end_reached = ADVANCE;
7262 			else if (ret < 0)
7263 				goto out_unlock;
7264 			advance_right = 0;
7265 		}
7266 
7267 		if (left_end_reached && right_end_reached) {
7268 			ret = 0;
7269 			goto out_unlock;
7270 		} else if (left_end_reached) {
7271 			if (right_level == 0) {
7272 				up_read(&fs_info->commit_root_sem);
7273 				ret = changed_cb(left_path, right_path,
7274 						&right_key,
7275 						BTRFS_COMPARE_TREE_DELETED,
7276 						sctx);
7277 				if (ret < 0)
7278 					goto out;
7279 				down_read(&fs_info->commit_root_sem);
7280 			}
7281 			advance_right = ADVANCE;
7282 			continue;
7283 		} else if (right_end_reached) {
7284 			if (left_level == 0) {
7285 				up_read(&fs_info->commit_root_sem);
7286 				ret = changed_cb(left_path, right_path,
7287 						&left_key,
7288 						BTRFS_COMPARE_TREE_NEW,
7289 						sctx);
7290 				if (ret < 0)
7291 					goto out;
7292 				down_read(&fs_info->commit_root_sem);
7293 			}
7294 			advance_left = ADVANCE;
7295 			continue;
7296 		}
7297 
7298 		if (left_level == 0 && right_level == 0) {
7299 			up_read(&fs_info->commit_root_sem);
7300 			cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
7301 			if (cmp < 0) {
7302 				ret = changed_cb(left_path, right_path,
7303 						&left_key,
7304 						BTRFS_COMPARE_TREE_NEW,
7305 						sctx);
7306 				advance_left = ADVANCE;
7307 			} else if (cmp > 0) {
7308 				ret = changed_cb(left_path, right_path,
7309 						&right_key,
7310 						BTRFS_COMPARE_TREE_DELETED,
7311 						sctx);
7312 				advance_right = ADVANCE;
7313 			} else {
7314 				enum btrfs_compare_tree_result result;
7315 
7316 				WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
7317 				ret = tree_compare_item(left_path, right_path,
7318 							tmp_buf);
7319 				if (ret)
7320 					result = BTRFS_COMPARE_TREE_CHANGED;
7321 				else
7322 					result = BTRFS_COMPARE_TREE_SAME;
7323 				ret = changed_cb(left_path, right_path,
7324 						 &left_key, result, sctx);
7325 				advance_left = ADVANCE;
7326 				advance_right = ADVANCE;
7327 			}
7328 
7329 			if (ret < 0)
7330 				goto out;
7331 			down_read(&fs_info->commit_root_sem);
7332 		} else if (left_level == right_level) {
7333 			cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
7334 			if (cmp < 0) {
7335 				advance_left = ADVANCE;
7336 			} else if (cmp > 0) {
7337 				advance_right = ADVANCE;
7338 			} else {
7339 				left_blockptr = btrfs_node_blockptr(
7340 						left_path->nodes[left_level],
7341 						left_path->slots[left_level]);
7342 				right_blockptr = btrfs_node_blockptr(
7343 						right_path->nodes[right_level],
7344 						right_path->slots[right_level]);
7345 				left_gen = btrfs_node_ptr_generation(
7346 						left_path->nodes[left_level],
7347 						left_path->slots[left_level]);
7348 				right_gen = btrfs_node_ptr_generation(
7349 						right_path->nodes[right_level],
7350 						right_path->slots[right_level]);
7351 				if (left_blockptr == right_blockptr &&
7352 				    left_gen == right_gen) {
7353 					/*
7354 					 * As we're on a shared block, don't
7355 					 * allow to go deeper.
7356 					 */
7357 					advance_left = ADVANCE_ONLY_NEXT;
7358 					advance_right = ADVANCE_ONLY_NEXT;
7359 				} else {
7360 					advance_left = ADVANCE;
7361 					advance_right = ADVANCE;
7362 				}
7363 			}
7364 		} else if (left_level < right_level) {
7365 			advance_right = ADVANCE;
7366 		} else {
7367 			advance_left = ADVANCE;
7368 		}
7369 	}
7370 
7371 out_unlock:
7372 	up_read(&fs_info->commit_root_sem);
7373 out:
7374 	btrfs_free_path(left_path);
7375 	btrfs_free_path(right_path);
7376 	kvfree(tmp_buf);
7377 	return ret;
7378 }
7379 
send_subvol(struct send_ctx * sctx)7380 static int send_subvol(struct send_ctx *sctx)
7381 {
7382 	int ret;
7383 
7384 	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_STREAM_HEADER)) {
7385 		ret = send_header(sctx);
7386 		if (ret < 0)
7387 			goto out;
7388 	}
7389 
7390 	ret = send_subvol_begin(sctx);
7391 	if (ret < 0)
7392 		goto out;
7393 
7394 	if (sctx->parent_root) {
7395 		ret = btrfs_compare_trees(sctx->send_root, sctx->parent_root, sctx);
7396 		if (ret < 0)
7397 			goto out;
7398 		ret = finish_inode_if_needed(sctx, 1);
7399 		if (ret < 0)
7400 			goto out;
7401 	} else {
7402 		ret = full_send_tree(sctx);
7403 		if (ret < 0)
7404 			goto out;
7405 	}
7406 
7407 out:
7408 	free_recorded_refs(sctx);
7409 	return ret;
7410 }
7411 
7412 /*
7413  * If orphan cleanup did remove any orphans from a root, it means the tree
7414  * was modified and therefore the commit root is not the same as the current
7415  * root anymore. This is a problem, because send uses the commit root and
7416  * therefore can see inode items that don't exist in the current root anymore,
7417  * and for example make calls to btrfs_iget, which will do tree lookups based
7418  * on the current root and not on the commit root. Those lookups will fail,
7419  * returning a -ESTALE error, and making send fail with that error. So make
7420  * sure a send does not see any orphans we have just removed, and that it will
7421  * see the same inodes regardless of whether a transaction commit happened
7422  * before it started (meaning that the commit root will be the same as the
7423  * current root) or not.
7424  */
ensure_commit_roots_uptodate(struct send_ctx * sctx)7425 static int ensure_commit_roots_uptodate(struct send_ctx *sctx)
7426 {
7427 	int i;
7428 	struct btrfs_trans_handle *trans = NULL;
7429 
7430 again:
7431 	if (sctx->parent_root &&
7432 	    sctx->parent_root->node != sctx->parent_root->commit_root)
7433 		goto commit_trans;
7434 
7435 	for (i = 0; i < sctx->clone_roots_cnt; i++)
7436 		if (sctx->clone_roots[i].root->node !=
7437 		    sctx->clone_roots[i].root->commit_root)
7438 			goto commit_trans;
7439 
7440 	if (trans)
7441 		return btrfs_end_transaction(trans);
7442 
7443 	return 0;
7444 
7445 commit_trans:
7446 	/* Use any root, all fs roots will get their commit roots updated. */
7447 	if (!trans) {
7448 		trans = btrfs_join_transaction(sctx->send_root);
7449 		if (IS_ERR(trans))
7450 			return PTR_ERR(trans);
7451 		goto again;
7452 	}
7453 
7454 	return btrfs_commit_transaction(trans);
7455 }
7456 
7457 /*
7458  * Make sure any existing dellaloc is flushed for any root used by a send
7459  * operation so that we do not miss any data and we do not race with writeback
7460  * finishing and changing a tree while send is using the tree. This could
7461  * happen if a subvolume is in RW mode, has delalloc, is turned to RO mode and
7462  * a send operation then uses the subvolume.
7463  * After flushing delalloc ensure_commit_roots_uptodate() must be called.
7464  */
flush_delalloc_roots(struct send_ctx * sctx)7465 static int flush_delalloc_roots(struct send_ctx *sctx)
7466 {
7467 	struct btrfs_root *root = sctx->parent_root;
7468 	int ret;
7469 	int i;
7470 
7471 	if (root) {
7472 		ret = btrfs_start_delalloc_snapshot(root, false);
7473 		if (ret)
7474 			return ret;
7475 		btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
7476 	}
7477 
7478 	for (i = 0; i < sctx->clone_roots_cnt; i++) {
7479 		root = sctx->clone_roots[i].root;
7480 		ret = btrfs_start_delalloc_snapshot(root, false);
7481 		if (ret)
7482 			return ret;
7483 		btrfs_wait_ordered_extents(root, U64_MAX, 0, U64_MAX);
7484 	}
7485 
7486 	return 0;
7487 }
7488 
btrfs_root_dec_send_in_progress(struct btrfs_root * root)7489 static void btrfs_root_dec_send_in_progress(struct btrfs_root* root)
7490 {
7491 	spin_lock(&root->root_item_lock);
7492 	root->send_in_progress--;
7493 	/*
7494 	 * Not much left to do, we don't know why it's unbalanced and
7495 	 * can't blindly reset it to 0.
7496 	 */
7497 	if (root->send_in_progress < 0)
7498 		btrfs_err(root->fs_info,
7499 			  "send_in_progress unbalanced %d root %llu",
7500 			  root->send_in_progress, root->root_key.objectid);
7501 	spin_unlock(&root->root_item_lock);
7502 }
7503 
dedupe_in_progress_warn(const struct btrfs_root * root)7504 static void dedupe_in_progress_warn(const struct btrfs_root *root)
7505 {
7506 	btrfs_warn_rl(root->fs_info,
7507 "cannot use root %llu for send while deduplications on it are in progress (%d in progress)",
7508 		      root->root_key.objectid, root->dedupe_in_progress);
7509 }
7510 
btrfs_ioctl_send(struct file * mnt_file,struct btrfs_ioctl_send_args * arg)7511 long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
7512 {
7513 	int ret = 0;
7514 	struct btrfs_root *send_root = BTRFS_I(file_inode(mnt_file))->root;
7515 	struct btrfs_fs_info *fs_info = send_root->fs_info;
7516 	struct btrfs_root *clone_root;
7517 	struct send_ctx *sctx = NULL;
7518 	u32 i;
7519 	u64 *clone_sources_tmp = NULL;
7520 	int clone_sources_to_rollback = 0;
7521 	size_t alloc_size;
7522 	int sort_clone_roots = 0;
7523 
7524 	if (!capable(CAP_SYS_ADMIN))
7525 		return -EPERM;
7526 
7527 	/*
7528 	 * The subvolume must remain read-only during send, protect against
7529 	 * making it RW. This also protects against deletion.
7530 	 */
7531 	spin_lock(&send_root->root_item_lock);
7532 	if (btrfs_root_readonly(send_root) && send_root->dedupe_in_progress) {
7533 		dedupe_in_progress_warn(send_root);
7534 		spin_unlock(&send_root->root_item_lock);
7535 		return -EAGAIN;
7536 	}
7537 	send_root->send_in_progress++;
7538 	spin_unlock(&send_root->root_item_lock);
7539 
7540 	/*
7541 	 * Userspace tools do the checks and warn the user if it's
7542 	 * not RO.
7543 	 */
7544 	if (!btrfs_root_readonly(send_root)) {
7545 		ret = -EPERM;
7546 		goto out;
7547 	}
7548 
7549 	/*
7550 	 * Check that we don't overflow at later allocations, we request
7551 	 * clone_sources_count + 1 items, and compare to unsigned long inside
7552 	 * access_ok. Also set an upper limit for allocation size so this can't
7553 	 * easily exhaust memory. Max number of clone sources is about 200K.
7554 	 */
7555 	if (arg->clone_sources_count > SZ_8M / sizeof(struct clone_root)) {
7556 		ret = -EINVAL;
7557 		goto out;
7558 	}
7559 
7560 	if (arg->flags & ~BTRFS_SEND_FLAG_MASK) {
7561 		ret = -EOPNOTSUPP;
7562 		goto out;
7563 	}
7564 
7565 	sctx = kzalloc(sizeof(struct send_ctx), GFP_KERNEL);
7566 	if (!sctx) {
7567 		ret = -ENOMEM;
7568 		goto out;
7569 	}
7570 
7571 	INIT_LIST_HEAD(&sctx->new_refs);
7572 	INIT_LIST_HEAD(&sctx->deleted_refs);
7573 	INIT_RADIX_TREE(&sctx->name_cache, GFP_KERNEL);
7574 	INIT_LIST_HEAD(&sctx->name_cache_list);
7575 
7576 	sctx->flags = arg->flags;
7577 
7578 	sctx->send_filp = fget(arg->send_fd);
7579 	if (!sctx->send_filp || !(sctx->send_filp->f_mode & FMODE_WRITE)) {
7580 		ret = -EBADF;
7581 		goto out;
7582 	}
7583 
7584 	sctx->send_root = send_root;
7585 	/*
7586 	 * Unlikely but possible, if the subvolume is marked for deletion but
7587 	 * is slow to remove the directory entry, send can still be started
7588 	 */
7589 	if (btrfs_root_dead(sctx->send_root)) {
7590 		ret = -EPERM;
7591 		goto out;
7592 	}
7593 
7594 	sctx->clone_roots_cnt = arg->clone_sources_count;
7595 
7596 	sctx->send_max_size = BTRFS_SEND_BUF_SIZE;
7597 	sctx->send_buf = kvmalloc(sctx->send_max_size, GFP_KERNEL);
7598 	if (!sctx->send_buf) {
7599 		ret = -ENOMEM;
7600 		goto out;
7601 	}
7602 
7603 	sctx->pending_dir_moves = RB_ROOT;
7604 	sctx->waiting_dir_moves = RB_ROOT;
7605 	sctx->orphan_dirs = RB_ROOT;
7606 
7607 	sctx->clone_roots = kvcalloc(sizeof(*sctx->clone_roots),
7608 				     arg->clone_sources_count + 1,
7609 				     GFP_KERNEL);
7610 	if (!sctx->clone_roots) {
7611 		ret = -ENOMEM;
7612 		goto out;
7613 	}
7614 
7615 	alloc_size = array_size(sizeof(*arg->clone_sources),
7616 				arg->clone_sources_count);
7617 
7618 	if (arg->clone_sources_count) {
7619 		clone_sources_tmp = kvmalloc(alloc_size, GFP_KERNEL);
7620 		if (!clone_sources_tmp) {
7621 			ret = -ENOMEM;
7622 			goto out;
7623 		}
7624 
7625 		ret = copy_from_user(clone_sources_tmp, arg->clone_sources,
7626 				alloc_size);
7627 		if (ret) {
7628 			ret = -EFAULT;
7629 			goto out;
7630 		}
7631 
7632 		for (i = 0; i < arg->clone_sources_count; i++) {
7633 			clone_root = btrfs_get_fs_root(fs_info,
7634 						clone_sources_tmp[i], true);
7635 			if (IS_ERR(clone_root)) {
7636 				ret = PTR_ERR(clone_root);
7637 				goto out;
7638 			}
7639 			spin_lock(&clone_root->root_item_lock);
7640 			if (!btrfs_root_readonly(clone_root) ||
7641 			    btrfs_root_dead(clone_root)) {
7642 				spin_unlock(&clone_root->root_item_lock);
7643 				btrfs_put_root(clone_root);
7644 				ret = -EPERM;
7645 				goto out;
7646 			}
7647 			if (clone_root->dedupe_in_progress) {
7648 				dedupe_in_progress_warn(clone_root);
7649 				spin_unlock(&clone_root->root_item_lock);
7650 				btrfs_put_root(clone_root);
7651 				ret = -EAGAIN;
7652 				goto out;
7653 			}
7654 			clone_root->send_in_progress++;
7655 			spin_unlock(&clone_root->root_item_lock);
7656 
7657 			sctx->clone_roots[i].root = clone_root;
7658 			clone_sources_to_rollback = i + 1;
7659 		}
7660 		kvfree(clone_sources_tmp);
7661 		clone_sources_tmp = NULL;
7662 	}
7663 
7664 	if (arg->parent_root) {
7665 		sctx->parent_root = btrfs_get_fs_root(fs_info, arg->parent_root,
7666 						      true);
7667 		if (IS_ERR(sctx->parent_root)) {
7668 			ret = PTR_ERR(sctx->parent_root);
7669 			goto out;
7670 		}
7671 
7672 		spin_lock(&sctx->parent_root->root_item_lock);
7673 		sctx->parent_root->send_in_progress++;
7674 		if (!btrfs_root_readonly(sctx->parent_root) ||
7675 				btrfs_root_dead(sctx->parent_root)) {
7676 			spin_unlock(&sctx->parent_root->root_item_lock);
7677 			ret = -EPERM;
7678 			goto out;
7679 		}
7680 		if (sctx->parent_root->dedupe_in_progress) {
7681 			dedupe_in_progress_warn(sctx->parent_root);
7682 			spin_unlock(&sctx->parent_root->root_item_lock);
7683 			ret = -EAGAIN;
7684 			goto out;
7685 		}
7686 		spin_unlock(&sctx->parent_root->root_item_lock);
7687 	}
7688 
7689 	/*
7690 	 * Clones from send_root are allowed, but only if the clone source
7691 	 * is behind the current send position. This is checked while searching
7692 	 * for possible clone sources.
7693 	 */
7694 	sctx->clone_roots[sctx->clone_roots_cnt++].root =
7695 		btrfs_grab_root(sctx->send_root);
7696 
7697 	/* We do a bsearch later */
7698 	sort(sctx->clone_roots, sctx->clone_roots_cnt,
7699 			sizeof(*sctx->clone_roots), __clone_root_cmp_sort,
7700 			NULL);
7701 	sort_clone_roots = 1;
7702 
7703 	ret = flush_delalloc_roots(sctx);
7704 	if (ret)
7705 		goto out;
7706 
7707 	ret = ensure_commit_roots_uptodate(sctx);
7708 	if (ret)
7709 		goto out;
7710 
7711 	ret = send_subvol(sctx);
7712 	if (ret < 0)
7713 		goto out;
7714 
7715 	if (!(sctx->flags & BTRFS_SEND_FLAG_OMIT_END_CMD)) {
7716 		ret = begin_cmd(sctx, BTRFS_SEND_C_END);
7717 		if (ret < 0)
7718 			goto out;
7719 		ret = send_cmd(sctx);
7720 		if (ret < 0)
7721 			goto out;
7722 	}
7723 
7724 out:
7725 	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->pending_dir_moves));
7726 	while (sctx && !RB_EMPTY_ROOT(&sctx->pending_dir_moves)) {
7727 		struct rb_node *n;
7728 		struct pending_dir_move *pm;
7729 
7730 		n = rb_first(&sctx->pending_dir_moves);
7731 		pm = rb_entry(n, struct pending_dir_move, node);
7732 		while (!list_empty(&pm->list)) {
7733 			struct pending_dir_move *pm2;
7734 
7735 			pm2 = list_first_entry(&pm->list,
7736 					       struct pending_dir_move, list);
7737 			free_pending_move(sctx, pm2);
7738 		}
7739 		free_pending_move(sctx, pm);
7740 	}
7741 
7742 	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves));
7743 	while (sctx && !RB_EMPTY_ROOT(&sctx->waiting_dir_moves)) {
7744 		struct rb_node *n;
7745 		struct waiting_dir_move *dm;
7746 
7747 		n = rb_first(&sctx->waiting_dir_moves);
7748 		dm = rb_entry(n, struct waiting_dir_move, node);
7749 		rb_erase(&dm->node, &sctx->waiting_dir_moves);
7750 		kfree(dm);
7751 	}
7752 
7753 	WARN_ON(sctx && !ret && !RB_EMPTY_ROOT(&sctx->orphan_dirs));
7754 	while (sctx && !RB_EMPTY_ROOT(&sctx->orphan_dirs)) {
7755 		struct rb_node *n;
7756 		struct orphan_dir_info *odi;
7757 
7758 		n = rb_first(&sctx->orphan_dirs);
7759 		odi = rb_entry(n, struct orphan_dir_info, node);
7760 		free_orphan_dir_info(sctx, odi);
7761 	}
7762 
7763 	if (sort_clone_roots) {
7764 		for (i = 0; i < sctx->clone_roots_cnt; i++) {
7765 			btrfs_root_dec_send_in_progress(
7766 					sctx->clone_roots[i].root);
7767 			btrfs_put_root(sctx->clone_roots[i].root);
7768 		}
7769 	} else {
7770 		for (i = 0; sctx && i < clone_sources_to_rollback; i++) {
7771 			btrfs_root_dec_send_in_progress(
7772 					sctx->clone_roots[i].root);
7773 			btrfs_put_root(sctx->clone_roots[i].root);
7774 		}
7775 
7776 		btrfs_root_dec_send_in_progress(send_root);
7777 	}
7778 	if (sctx && !IS_ERR_OR_NULL(sctx->parent_root)) {
7779 		btrfs_root_dec_send_in_progress(sctx->parent_root);
7780 		btrfs_put_root(sctx->parent_root);
7781 	}
7782 
7783 	kvfree(clone_sources_tmp);
7784 
7785 	if (sctx) {
7786 		if (sctx->send_filp)
7787 			fput(sctx->send_filp);
7788 
7789 		kvfree(sctx->clone_roots);
7790 		kvfree(sctx->send_buf);
7791 
7792 		name_cache_free(sctx);
7793 
7794 		kfree(sctx);
7795 	}
7796 
7797 	return ret;
7798 }
7799