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1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2007 Oracle.  All rights reserved.
4  */
5 
6 #include <linux/err.h>
7 #include <linux/uuid.h>
8 #include "ctree.h"
9 #include "transaction.h"
10 #include "disk-io.h"
11 #include "print-tree.h"
12 #include "qgroup.h"
13 #include "space-info.h"
14 
15 /*
16  * Read a root item from the tree. In case we detect a root item smaller then
17  * sizeof(root_item), we know it's an old version of the root structure and
18  * initialize all new fields to zero. The same happens if we detect mismatching
19  * generation numbers as then we know the root was once mounted with an older
20  * kernel that was not aware of the root item structure change.
21  */
btrfs_read_root_item(struct extent_buffer * eb,int slot,struct btrfs_root_item * item)22 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
23 				struct btrfs_root_item *item)
24 {
25 	u32 len;
26 	int need_reset = 0;
27 
28 	len = btrfs_item_size_nr(eb, slot);
29 	read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
30 			   min_t(u32, len, sizeof(*item)));
31 	if (len < sizeof(*item))
32 		need_reset = 1;
33 	if (!need_reset && btrfs_root_generation(item)
34 		!= btrfs_root_generation_v2(item)) {
35 		if (btrfs_root_generation_v2(item) != 0) {
36 			btrfs_warn(eb->fs_info,
37 					"mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
38 		}
39 		need_reset = 1;
40 	}
41 	if (need_reset) {
42 		memset(&item->generation_v2, 0,
43 			sizeof(*item) - offsetof(struct btrfs_root_item,
44 					generation_v2));
45 
46 		generate_random_guid(item->uuid);
47 	}
48 }
49 
50 /*
51  * btrfs_find_root - lookup the root by the key.
52  * root: the root of the root tree
53  * search_key: the key to search
54  * path: the path we search
55  * root_item: the root item of the tree we look for
56  * root_key: the root key of the tree we look for
57  *
58  * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
59  * of the search key, just lookup the root with the highest offset for a
60  * given objectid.
61  *
62  * If we find something return 0, otherwise > 0, < 0 on error.
63  */
btrfs_find_root(struct btrfs_root * root,const struct btrfs_key * search_key,struct btrfs_path * path,struct btrfs_root_item * root_item,struct btrfs_key * root_key)64 int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
65 		    struct btrfs_path *path, struct btrfs_root_item *root_item,
66 		    struct btrfs_key *root_key)
67 {
68 	struct btrfs_key found_key;
69 	struct extent_buffer *l;
70 	int ret;
71 	int slot;
72 
73 	ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
74 	if (ret < 0)
75 		return ret;
76 
77 	if (search_key->offset != -1ULL) {	/* the search key is exact */
78 		if (ret > 0)
79 			goto out;
80 	} else {
81 		BUG_ON(ret == 0);		/* Logical error */
82 		if (path->slots[0] == 0)
83 			goto out;
84 		path->slots[0]--;
85 		ret = 0;
86 	}
87 
88 	l = path->nodes[0];
89 	slot = path->slots[0];
90 
91 	btrfs_item_key_to_cpu(l, &found_key, slot);
92 	if (found_key.objectid != search_key->objectid ||
93 	    found_key.type != BTRFS_ROOT_ITEM_KEY) {
94 		ret = 1;
95 		goto out;
96 	}
97 
98 	if (root_item)
99 		btrfs_read_root_item(l, slot, root_item);
100 	if (root_key)
101 		memcpy(root_key, &found_key, sizeof(found_key));
102 out:
103 	btrfs_release_path(path);
104 	return ret;
105 }
106 
btrfs_set_root_node(struct btrfs_root_item * item,struct extent_buffer * node)107 void btrfs_set_root_node(struct btrfs_root_item *item,
108 			 struct extent_buffer *node)
109 {
110 	btrfs_set_root_bytenr(item, node->start);
111 	btrfs_set_root_level(item, btrfs_header_level(node));
112 	btrfs_set_root_generation(item, btrfs_header_generation(node));
113 }
114 
115 /*
116  * copy the data in 'item' into the btree
117  */
btrfs_update_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_key * key,struct btrfs_root_item * item)118 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
119 		      *root, struct btrfs_key *key, struct btrfs_root_item
120 		      *item)
121 {
122 	struct btrfs_fs_info *fs_info = root->fs_info;
123 	struct btrfs_path *path;
124 	struct extent_buffer *l;
125 	int ret;
126 	int slot;
127 	unsigned long ptr;
128 	u32 old_len;
129 
130 	path = btrfs_alloc_path();
131 	if (!path)
132 		return -ENOMEM;
133 
134 	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
135 	if (ret < 0)
136 		goto out;
137 
138 	if (ret > 0) {
139 		btrfs_crit(fs_info,
140 			"unable to find root key (%llu %u %llu) in tree %llu",
141 			key->objectid, key->type, key->offset,
142 			root->root_key.objectid);
143 		ret = -EUCLEAN;
144 		btrfs_abort_transaction(trans, ret);
145 		goto out;
146 	}
147 
148 	l = path->nodes[0];
149 	slot = path->slots[0];
150 	ptr = btrfs_item_ptr_offset(l, slot);
151 	old_len = btrfs_item_size_nr(l, slot);
152 
153 	/*
154 	 * If this is the first time we update the root item which originated
155 	 * from an older kernel, we need to enlarge the item size to make room
156 	 * for the added fields.
157 	 */
158 	if (old_len < sizeof(*item)) {
159 		btrfs_release_path(path);
160 		ret = btrfs_search_slot(trans, root, key, path,
161 				-1, 1);
162 		if (ret < 0) {
163 			btrfs_abort_transaction(trans, ret);
164 			goto out;
165 		}
166 
167 		ret = btrfs_del_item(trans, root, path);
168 		if (ret < 0) {
169 			btrfs_abort_transaction(trans, ret);
170 			goto out;
171 		}
172 		btrfs_release_path(path);
173 		ret = btrfs_insert_empty_item(trans, root, path,
174 				key, sizeof(*item));
175 		if (ret < 0) {
176 			btrfs_abort_transaction(trans, ret);
177 			goto out;
178 		}
179 		l = path->nodes[0];
180 		slot = path->slots[0];
181 		ptr = btrfs_item_ptr_offset(l, slot);
182 	}
183 
184 	/*
185 	 * Update generation_v2 so at the next mount we know the new root
186 	 * fields are valid.
187 	 */
188 	btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
189 
190 	write_extent_buffer(l, item, ptr, sizeof(*item));
191 	btrfs_mark_buffer_dirty(path->nodes[0]);
192 out:
193 	btrfs_free_path(path);
194 	return ret;
195 }
196 
btrfs_insert_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,const struct btrfs_key * key,struct btrfs_root_item * item)197 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
198 		      const struct btrfs_key *key, struct btrfs_root_item *item)
199 {
200 	/*
201 	 * Make sure generation v1 and v2 match. See update_root for details.
202 	 */
203 	btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
204 	return btrfs_insert_item(trans, root, key, item, sizeof(*item));
205 }
206 
btrfs_find_orphan_roots(struct btrfs_fs_info * fs_info)207 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
208 {
209 	struct btrfs_root *tree_root = fs_info->tree_root;
210 	struct extent_buffer *leaf;
211 	struct btrfs_path *path;
212 	struct btrfs_key key;
213 	struct btrfs_root *root;
214 	int err = 0;
215 	int ret;
216 
217 	path = btrfs_alloc_path();
218 	if (!path)
219 		return -ENOMEM;
220 
221 	key.objectid = BTRFS_ORPHAN_OBJECTID;
222 	key.type = BTRFS_ORPHAN_ITEM_KEY;
223 	key.offset = 0;
224 
225 	while (1) {
226 		u64 root_objectid;
227 
228 		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
229 		if (ret < 0) {
230 			err = ret;
231 			break;
232 		}
233 
234 		leaf = path->nodes[0];
235 		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
236 			ret = btrfs_next_leaf(tree_root, path);
237 			if (ret < 0)
238 				err = ret;
239 			if (ret != 0)
240 				break;
241 			leaf = path->nodes[0];
242 		}
243 
244 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
245 		btrfs_release_path(path);
246 
247 		if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
248 		    key.type != BTRFS_ORPHAN_ITEM_KEY)
249 			break;
250 
251 		root_objectid = key.offset;
252 		key.offset++;
253 
254 		root = btrfs_get_fs_root(fs_info, root_objectid, false);
255 		err = PTR_ERR_OR_ZERO(root);
256 		if (err && err != -ENOENT) {
257 			break;
258 		} else if (err == -ENOENT) {
259 			struct btrfs_trans_handle *trans;
260 
261 			btrfs_release_path(path);
262 
263 			trans = btrfs_join_transaction(tree_root);
264 			if (IS_ERR(trans)) {
265 				err = PTR_ERR(trans);
266 				btrfs_handle_fs_error(fs_info, err,
267 					    "Failed to start trans to delete orphan item");
268 				break;
269 			}
270 			err = btrfs_del_orphan_item(trans, tree_root,
271 						    root_objectid);
272 			btrfs_end_transaction(trans);
273 			if (err) {
274 				btrfs_handle_fs_error(fs_info, err,
275 					    "Failed to delete root orphan item");
276 				break;
277 			}
278 			continue;
279 		}
280 
281 		WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state));
282 		if (btrfs_root_refs(&root->root_item) == 0) {
283 			set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
284 			btrfs_add_dead_root(root);
285 		}
286 		btrfs_put_root(root);
287 	}
288 
289 	btrfs_free_path(path);
290 	return err;
291 }
292 
293 /* drop the root item for 'key' from the tree root */
btrfs_del_root(struct btrfs_trans_handle * trans,const struct btrfs_key * key)294 int btrfs_del_root(struct btrfs_trans_handle *trans,
295 		   const struct btrfs_key *key)
296 {
297 	struct btrfs_root *root = trans->fs_info->tree_root;
298 	struct btrfs_path *path;
299 	int ret;
300 
301 	path = btrfs_alloc_path();
302 	if (!path)
303 		return -ENOMEM;
304 	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
305 	if (ret < 0)
306 		goto out;
307 
308 	BUG_ON(ret != 0);
309 
310 	ret = btrfs_del_item(trans, root, path);
311 out:
312 	btrfs_free_path(path);
313 	return ret;
314 }
315 
btrfs_del_root_ref(struct btrfs_trans_handle * trans,u64 root_id,u64 ref_id,u64 dirid,u64 * sequence,const char * name,int name_len)316 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
317 		       u64 ref_id, u64 dirid, u64 *sequence, const char *name,
318 		       int name_len)
319 
320 {
321 	struct btrfs_root *tree_root = trans->fs_info->tree_root;
322 	struct btrfs_path *path;
323 	struct btrfs_root_ref *ref;
324 	struct extent_buffer *leaf;
325 	struct btrfs_key key;
326 	unsigned long ptr;
327 	int err = 0;
328 	int ret;
329 
330 	path = btrfs_alloc_path();
331 	if (!path)
332 		return -ENOMEM;
333 
334 	key.objectid = root_id;
335 	key.type = BTRFS_ROOT_BACKREF_KEY;
336 	key.offset = ref_id;
337 again:
338 	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
339 	if (ret < 0) {
340 		err = ret;
341 		goto out;
342 	} else if (ret == 0) {
343 		leaf = path->nodes[0];
344 		ref = btrfs_item_ptr(leaf, path->slots[0],
345 				     struct btrfs_root_ref);
346 		ptr = (unsigned long)(ref + 1);
347 		if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
348 		    (btrfs_root_ref_name_len(leaf, ref) != name_len) ||
349 		    memcmp_extent_buffer(leaf, name, ptr, name_len)) {
350 			err = -ENOENT;
351 			goto out;
352 		}
353 		*sequence = btrfs_root_ref_sequence(leaf, ref);
354 
355 		ret = btrfs_del_item(trans, tree_root, path);
356 		if (ret) {
357 			err = ret;
358 			goto out;
359 		}
360 	} else
361 		err = -ENOENT;
362 
363 	if (key.type == BTRFS_ROOT_BACKREF_KEY) {
364 		btrfs_release_path(path);
365 		key.objectid = ref_id;
366 		key.type = BTRFS_ROOT_REF_KEY;
367 		key.offset = root_id;
368 		goto again;
369 	}
370 
371 out:
372 	btrfs_free_path(path);
373 	return err;
374 }
375 
376 /*
377  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
378  * or BTRFS_ROOT_BACKREF_KEY.
379  *
380  * The dirid, sequence, name and name_len refer to the directory entry
381  * that is referencing the root.
382  *
383  * For a forward ref, the root_id is the id of the tree referencing
384  * the root and ref_id is the id of the subvol  or snapshot.
385  *
386  * For a back ref the root_id is the id of the subvol or snapshot and
387  * ref_id is the id of the tree referencing it.
388  *
389  * Will return 0, -ENOMEM, or anything from the CoW path
390  */
btrfs_add_root_ref(struct btrfs_trans_handle * trans,u64 root_id,u64 ref_id,u64 dirid,u64 sequence,const char * name,int name_len)391 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
392 		       u64 ref_id, u64 dirid, u64 sequence, const char *name,
393 		       int name_len)
394 {
395 	struct btrfs_root *tree_root = trans->fs_info->tree_root;
396 	struct btrfs_key key;
397 	int ret;
398 	struct btrfs_path *path;
399 	struct btrfs_root_ref *ref;
400 	struct extent_buffer *leaf;
401 	unsigned long ptr;
402 
403 	path = btrfs_alloc_path();
404 	if (!path)
405 		return -ENOMEM;
406 
407 	key.objectid = root_id;
408 	key.type = BTRFS_ROOT_BACKREF_KEY;
409 	key.offset = ref_id;
410 again:
411 	ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
412 				      sizeof(*ref) + name_len);
413 	if (ret) {
414 		btrfs_abort_transaction(trans, ret);
415 		btrfs_free_path(path);
416 		return ret;
417 	}
418 
419 	leaf = path->nodes[0];
420 	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
421 	btrfs_set_root_ref_dirid(leaf, ref, dirid);
422 	btrfs_set_root_ref_sequence(leaf, ref, sequence);
423 	btrfs_set_root_ref_name_len(leaf, ref, name_len);
424 	ptr = (unsigned long)(ref + 1);
425 	write_extent_buffer(leaf, name, ptr, name_len);
426 	btrfs_mark_buffer_dirty(leaf);
427 
428 	if (key.type == BTRFS_ROOT_BACKREF_KEY) {
429 		btrfs_release_path(path);
430 		key.objectid = ref_id;
431 		key.type = BTRFS_ROOT_REF_KEY;
432 		key.offset = root_id;
433 		goto again;
434 	}
435 
436 	btrfs_free_path(path);
437 	return 0;
438 }
439 
440 /*
441  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
442  * for subvolumes. To work around this problem, we steal a bit from
443  * root_item->inode_item->flags, and use it to indicate if those fields
444  * have been properly initialized.
445  */
btrfs_check_and_init_root_item(struct btrfs_root_item * root_item)446 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
447 {
448 	u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
449 
450 	if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
451 		inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
452 		btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
453 		btrfs_set_root_flags(root_item, 0);
454 		btrfs_set_root_limit(root_item, 0);
455 	}
456 }
457 
btrfs_update_root_times(struct btrfs_trans_handle * trans,struct btrfs_root * root)458 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
459 			     struct btrfs_root *root)
460 {
461 	struct btrfs_root_item *item = &root->root_item;
462 	struct timespec64 ct;
463 
464 	ktime_get_real_ts64(&ct);
465 	spin_lock(&root->root_item_lock);
466 	btrfs_set_root_ctransid(item, trans->transid);
467 	btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
468 	btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
469 	spin_unlock(&root->root_item_lock);
470 }
471 
472 /*
473  * btrfs_subvolume_reserve_metadata() - reserve space for subvolume operation
474  * root: the root of the parent directory
475  * rsv: block reservation
476  * items: the number of items that we need do reservation
477  * use_global_rsv: allow fallback to the global block reservation
478  *
479  * This function is used to reserve the space for snapshot/subvolume
480  * creation and deletion. Those operations are different with the
481  * common file/directory operations, they change two fs/file trees
482  * and root tree, the number of items that the qgroup reserves is
483  * different with the free space reservation. So we can not use
484  * the space reservation mechanism in start_transaction().
485  */
btrfs_subvolume_reserve_metadata(struct btrfs_root * root,struct btrfs_block_rsv * rsv,int items,bool use_global_rsv)486 int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
487 				     struct btrfs_block_rsv *rsv, int items,
488 				     bool use_global_rsv)
489 {
490 	u64 qgroup_num_bytes = 0;
491 	u64 num_bytes;
492 	int ret;
493 	struct btrfs_fs_info *fs_info = root->fs_info;
494 	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
495 
496 	if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
497 		/* One for parent inode, two for dir entries */
498 		qgroup_num_bytes = 3 * fs_info->nodesize;
499 		ret = btrfs_qgroup_reserve_meta_prealloc(root,
500 				qgroup_num_bytes, true);
501 		if (ret)
502 			return ret;
503 	}
504 
505 	num_bytes = btrfs_calc_insert_metadata_size(fs_info, items);
506 	rsv->space_info = btrfs_find_space_info(fs_info,
507 					    BTRFS_BLOCK_GROUP_METADATA);
508 	ret = btrfs_block_rsv_add(root, rsv, num_bytes,
509 				  BTRFS_RESERVE_FLUSH_ALL);
510 
511 	if (ret == -ENOSPC && use_global_rsv)
512 		ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, true);
513 
514 	if (ret && qgroup_num_bytes)
515 		btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
516 
517 	if (!ret) {
518 		spin_lock(&rsv->lock);
519 		rsv->qgroup_rsv_reserved += qgroup_num_bytes;
520 		spin_unlock(&rsv->lock);
521 	}
522 	return ret;
523 }
524 
btrfs_subvolume_release_metadata(struct btrfs_root * root,struct btrfs_block_rsv * rsv)525 void btrfs_subvolume_release_metadata(struct btrfs_root *root,
526 				      struct btrfs_block_rsv *rsv)
527 {
528 	struct btrfs_fs_info *fs_info = root->fs_info;
529 	u64 qgroup_to_release;
530 
531 	btrfs_block_rsv_release(fs_info, rsv, (u64)-1, &qgroup_to_release);
532 	btrfs_qgroup_convert_reserved_meta(root, qgroup_to_release);
533 }
534