1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 */
5
6 #include <linux/sched.h>
7 #include <linux/slab.h>
8 #include <linux/rbtree.h>
9 #include <linux/mm.h>
10 #include <linux/error-injection.h>
11 #include "ctree.h"
12 #include "disk-io.h"
13 #include "transaction.h"
14 #include "print-tree.h"
15 #include "locking.h"
16 #include "volumes.h"
17 #include "qgroup.h"
18 #include "tree-mod-log.h"
19 #include "tree-checker.h"
20
21 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
22 *root, struct btrfs_path *path, int level);
23 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
24 const struct btrfs_key *ins_key, struct btrfs_path *path,
25 int data_size, int extend);
26 static int push_node_left(struct btrfs_trans_handle *trans,
27 struct extent_buffer *dst,
28 struct extent_buffer *src, int empty);
29 static int balance_node_right(struct btrfs_trans_handle *trans,
30 struct extent_buffer *dst_buf,
31 struct extent_buffer *src_buf);
32 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
33 int level, int slot);
34
35 static const struct btrfs_csums {
36 u16 size;
37 const char name[10];
38 const char driver[12];
39 } btrfs_csums[] = {
40 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
41 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
42 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
43 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
44 .driver = "blake2b-256" },
45 };
46
btrfs_super_csum_size(const struct btrfs_super_block * s)47 int btrfs_super_csum_size(const struct btrfs_super_block *s)
48 {
49 u16 t = btrfs_super_csum_type(s);
50 /*
51 * csum type is validated at mount time
52 */
53 return btrfs_csums[t].size;
54 }
55
btrfs_super_csum_name(u16 csum_type)56 const char *btrfs_super_csum_name(u16 csum_type)
57 {
58 /* csum type is validated at mount time */
59 return btrfs_csums[csum_type].name;
60 }
61
62 /*
63 * Return driver name if defined, otherwise the name that's also a valid driver
64 * name
65 */
btrfs_super_csum_driver(u16 csum_type)66 const char *btrfs_super_csum_driver(u16 csum_type)
67 {
68 /* csum type is validated at mount time */
69 return btrfs_csums[csum_type].driver[0] ?
70 btrfs_csums[csum_type].driver :
71 btrfs_csums[csum_type].name;
72 }
73
btrfs_get_num_csums(void)74 size_t __attribute_const__ btrfs_get_num_csums(void)
75 {
76 return ARRAY_SIZE(btrfs_csums);
77 }
78
btrfs_alloc_path(void)79 struct btrfs_path *btrfs_alloc_path(void)
80 {
81 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
82 }
83
84 /* this also releases the path */
btrfs_free_path(struct btrfs_path * p)85 void btrfs_free_path(struct btrfs_path *p)
86 {
87 if (!p)
88 return;
89 btrfs_release_path(p);
90 kmem_cache_free(btrfs_path_cachep, p);
91 }
92
93 /*
94 * path release drops references on the extent buffers in the path
95 * and it drops any locks held by this path
96 *
97 * It is safe to call this on paths that no locks or extent buffers held.
98 */
btrfs_release_path(struct btrfs_path * p)99 noinline void btrfs_release_path(struct btrfs_path *p)
100 {
101 int i;
102
103 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
104 p->slots[i] = 0;
105 if (!p->nodes[i])
106 continue;
107 if (p->locks[i]) {
108 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
109 p->locks[i] = 0;
110 }
111 free_extent_buffer(p->nodes[i]);
112 p->nodes[i] = NULL;
113 }
114 }
115
116 /*
117 * We want the transaction abort to print stack trace only for errors where the
118 * cause could be a bug, eg. due to ENOSPC, and not for common errors that are
119 * caused by external factors.
120 */
abort_should_print_stack(int errno)121 bool __cold abort_should_print_stack(int errno)
122 {
123 switch (errno) {
124 case -EIO:
125 case -EROFS:
126 case -ENOMEM:
127 return false;
128 }
129 return true;
130 }
131
132 /*
133 * safely gets a reference on the root node of a tree. A lock
134 * is not taken, so a concurrent writer may put a different node
135 * at the root of the tree. See btrfs_lock_root_node for the
136 * looping required.
137 *
138 * The extent buffer returned by this has a reference taken, so
139 * it won't disappear. It may stop being the root of the tree
140 * at any time because there are no locks held.
141 */
btrfs_root_node(struct btrfs_root * root)142 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
143 {
144 struct extent_buffer *eb;
145
146 while (1) {
147 rcu_read_lock();
148 eb = rcu_dereference(root->node);
149
150 /*
151 * RCU really hurts here, we could free up the root node because
152 * it was COWed but we may not get the new root node yet so do
153 * the inc_not_zero dance and if it doesn't work then
154 * synchronize_rcu and try again.
155 */
156 if (atomic_inc_not_zero(&eb->refs)) {
157 rcu_read_unlock();
158 break;
159 }
160 rcu_read_unlock();
161 synchronize_rcu();
162 }
163 return eb;
164 }
165
166 /*
167 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
168 * just get put onto a simple dirty list. Transaction walks this list to make
169 * sure they get properly updated on disk.
170 */
add_root_to_dirty_list(struct btrfs_root * root)171 static void add_root_to_dirty_list(struct btrfs_root *root)
172 {
173 struct btrfs_fs_info *fs_info = root->fs_info;
174
175 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
176 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
177 return;
178
179 spin_lock(&fs_info->trans_lock);
180 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
181 /* Want the extent tree to be the last on the list */
182 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
183 list_move_tail(&root->dirty_list,
184 &fs_info->dirty_cowonly_roots);
185 else
186 list_move(&root->dirty_list,
187 &fs_info->dirty_cowonly_roots);
188 }
189 spin_unlock(&fs_info->trans_lock);
190 }
191
192 /*
193 * used by snapshot creation to make a copy of a root for a tree with
194 * a given objectid. The buffer with the new root node is returned in
195 * cow_ret, and this func returns zero on success or a negative error code.
196 */
btrfs_copy_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct extent_buffer * buf,struct extent_buffer ** cow_ret,u64 new_root_objectid)197 int btrfs_copy_root(struct btrfs_trans_handle *trans,
198 struct btrfs_root *root,
199 struct extent_buffer *buf,
200 struct extent_buffer **cow_ret, u64 new_root_objectid)
201 {
202 struct btrfs_fs_info *fs_info = root->fs_info;
203 struct extent_buffer *cow;
204 int ret = 0;
205 int level;
206 struct btrfs_disk_key disk_key;
207
208 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
209 trans->transid != fs_info->running_transaction->transid);
210 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
211 trans->transid != root->last_trans);
212
213 level = btrfs_header_level(buf);
214 if (level == 0)
215 btrfs_item_key(buf, &disk_key, 0);
216 else
217 btrfs_node_key(buf, &disk_key, 0);
218
219 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
220 &disk_key, level, buf->start, 0,
221 BTRFS_NESTING_NEW_ROOT);
222 if (IS_ERR(cow))
223 return PTR_ERR(cow);
224
225 copy_extent_buffer_full(cow, buf);
226 btrfs_set_header_bytenr(cow, cow->start);
227 btrfs_set_header_generation(cow, trans->transid);
228 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
229 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
230 BTRFS_HEADER_FLAG_RELOC);
231 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
232 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
233 else
234 btrfs_set_header_owner(cow, new_root_objectid);
235
236 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
237
238 WARN_ON(btrfs_header_generation(buf) > trans->transid);
239 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
240 ret = btrfs_inc_ref(trans, root, cow, 1);
241 else
242 ret = btrfs_inc_ref(trans, root, cow, 0);
243 if (ret) {
244 btrfs_tree_unlock(cow);
245 free_extent_buffer(cow);
246 btrfs_abort_transaction(trans, ret);
247 return ret;
248 }
249
250 btrfs_mark_buffer_dirty(cow);
251 *cow_ret = cow;
252 return 0;
253 }
254
255 /*
256 * check if the tree block can be shared by multiple trees
257 */
btrfs_block_can_be_shared(struct btrfs_root * root,struct extent_buffer * buf)258 int btrfs_block_can_be_shared(struct btrfs_root *root,
259 struct extent_buffer *buf)
260 {
261 /*
262 * Tree blocks not in shareable trees and tree roots are never shared.
263 * If a block was allocated after the last snapshot and the block was
264 * not allocated by tree relocation, we know the block is not shared.
265 */
266 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
267 buf != root->node && buf != root->commit_root &&
268 (btrfs_header_generation(buf) <=
269 btrfs_root_last_snapshot(&root->root_item) ||
270 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
271 return 1;
272
273 return 0;
274 }
275
update_ref_for_cow(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct extent_buffer * buf,struct extent_buffer * cow,int * last_ref)276 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
277 struct btrfs_root *root,
278 struct extent_buffer *buf,
279 struct extent_buffer *cow,
280 int *last_ref)
281 {
282 struct btrfs_fs_info *fs_info = root->fs_info;
283 u64 refs;
284 u64 owner;
285 u64 flags;
286 u64 new_flags = 0;
287 int ret;
288
289 /*
290 * Backrefs update rules:
291 *
292 * Always use full backrefs for extent pointers in tree block
293 * allocated by tree relocation.
294 *
295 * If a shared tree block is no longer referenced by its owner
296 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
297 * use full backrefs for extent pointers in tree block.
298 *
299 * If a tree block is been relocating
300 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
301 * use full backrefs for extent pointers in tree block.
302 * The reason for this is some operations (such as drop tree)
303 * are only allowed for blocks use full backrefs.
304 */
305
306 if (btrfs_block_can_be_shared(root, buf)) {
307 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
308 btrfs_header_level(buf), 1,
309 &refs, &flags);
310 if (ret)
311 return ret;
312 if (refs == 0) {
313 ret = -EROFS;
314 btrfs_handle_fs_error(fs_info, ret, NULL);
315 return ret;
316 }
317 } else {
318 refs = 1;
319 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
320 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
321 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
322 else
323 flags = 0;
324 }
325
326 owner = btrfs_header_owner(buf);
327 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
328 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
329
330 if (refs > 1) {
331 if ((owner == root->root_key.objectid ||
332 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
333 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
334 ret = btrfs_inc_ref(trans, root, buf, 1);
335 if (ret)
336 return ret;
337
338 if (root->root_key.objectid ==
339 BTRFS_TREE_RELOC_OBJECTID) {
340 ret = btrfs_dec_ref(trans, root, buf, 0);
341 if (ret)
342 return ret;
343 ret = btrfs_inc_ref(trans, root, cow, 1);
344 if (ret)
345 return ret;
346 }
347 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
348 } else {
349
350 if (root->root_key.objectid ==
351 BTRFS_TREE_RELOC_OBJECTID)
352 ret = btrfs_inc_ref(trans, root, cow, 1);
353 else
354 ret = btrfs_inc_ref(trans, root, cow, 0);
355 if (ret)
356 return ret;
357 }
358 if (new_flags != 0) {
359 int level = btrfs_header_level(buf);
360
361 ret = btrfs_set_disk_extent_flags(trans, buf,
362 new_flags, level);
363 if (ret)
364 return ret;
365 }
366 } else {
367 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
368 if (root->root_key.objectid ==
369 BTRFS_TREE_RELOC_OBJECTID)
370 ret = btrfs_inc_ref(trans, root, cow, 1);
371 else
372 ret = btrfs_inc_ref(trans, root, cow, 0);
373 if (ret)
374 return ret;
375 ret = btrfs_dec_ref(trans, root, buf, 1);
376 if (ret)
377 return ret;
378 }
379 btrfs_clean_tree_block(buf);
380 *last_ref = 1;
381 }
382 return 0;
383 }
384
385 /*
386 * does the dirty work in cow of a single block. The parent block (if
387 * supplied) is updated to point to the new cow copy. The new buffer is marked
388 * dirty and returned locked. If you modify the block it needs to be marked
389 * dirty again.
390 *
391 * search_start -- an allocation hint for the new block
392 *
393 * empty_size -- a hint that you plan on doing more cow. This is the size in
394 * bytes the allocator should try to find free next to the block it returns.
395 * This is just a hint and may be ignored by the allocator.
396 */
__btrfs_cow_block(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct extent_buffer * buf,struct extent_buffer * parent,int parent_slot,struct extent_buffer ** cow_ret,u64 search_start,u64 empty_size,enum btrfs_lock_nesting nest)397 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
398 struct btrfs_root *root,
399 struct extent_buffer *buf,
400 struct extent_buffer *parent, int parent_slot,
401 struct extent_buffer **cow_ret,
402 u64 search_start, u64 empty_size,
403 enum btrfs_lock_nesting nest)
404 {
405 struct btrfs_fs_info *fs_info = root->fs_info;
406 struct btrfs_disk_key disk_key;
407 struct extent_buffer *cow;
408 int level, ret;
409 int last_ref = 0;
410 int unlock_orig = 0;
411 u64 parent_start = 0;
412
413 if (*cow_ret == buf)
414 unlock_orig = 1;
415
416 btrfs_assert_tree_write_locked(buf);
417
418 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
419 trans->transid != fs_info->running_transaction->transid);
420 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
421 trans->transid != root->last_trans);
422
423 level = btrfs_header_level(buf);
424
425 if (level == 0)
426 btrfs_item_key(buf, &disk_key, 0);
427 else
428 btrfs_node_key(buf, &disk_key, 0);
429
430 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
431 parent_start = parent->start;
432
433 cow = btrfs_alloc_tree_block(trans, root, parent_start,
434 root->root_key.objectid, &disk_key, level,
435 search_start, empty_size, nest);
436 if (IS_ERR(cow))
437 return PTR_ERR(cow);
438
439 /* cow is set to blocking by btrfs_init_new_buffer */
440
441 copy_extent_buffer_full(cow, buf);
442 btrfs_set_header_bytenr(cow, cow->start);
443 btrfs_set_header_generation(cow, trans->transid);
444 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
445 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
446 BTRFS_HEADER_FLAG_RELOC);
447 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
448 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
449 else
450 btrfs_set_header_owner(cow, root->root_key.objectid);
451
452 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
453
454 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
455 if (ret) {
456 btrfs_tree_unlock(cow);
457 free_extent_buffer(cow);
458 btrfs_abort_transaction(trans, ret);
459 return ret;
460 }
461
462 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
463 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
464 if (ret) {
465 btrfs_tree_unlock(cow);
466 free_extent_buffer(cow);
467 btrfs_abort_transaction(trans, ret);
468 return ret;
469 }
470 }
471
472 if (buf == root->node) {
473 WARN_ON(parent && parent != buf);
474 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
475 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
476 parent_start = buf->start;
477
478 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
479 if (ret < 0) {
480 btrfs_tree_unlock(cow);
481 free_extent_buffer(cow);
482 btrfs_abort_transaction(trans, ret);
483 return ret;
484 }
485 atomic_inc(&cow->refs);
486 rcu_assign_pointer(root->node, cow);
487
488 btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
489 parent_start, last_ref);
490 free_extent_buffer(buf);
491 add_root_to_dirty_list(root);
492 } else {
493 WARN_ON(trans->transid != btrfs_header_generation(parent));
494 btrfs_tree_mod_log_insert_key(parent, parent_slot,
495 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
496 btrfs_set_node_blockptr(parent, parent_slot,
497 cow->start);
498 btrfs_set_node_ptr_generation(parent, parent_slot,
499 trans->transid);
500 btrfs_mark_buffer_dirty(parent);
501 if (last_ref) {
502 ret = btrfs_tree_mod_log_free_eb(buf);
503 if (ret) {
504 btrfs_tree_unlock(cow);
505 free_extent_buffer(cow);
506 btrfs_abort_transaction(trans, ret);
507 return ret;
508 }
509 }
510 btrfs_free_tree_block(trans, btrfs_root_id(root), buf,
511 parent_start, last_ref);
512 }
513 if (unlock_orig)
514 btrfs_tree_unlock(buf);
515 free_extent_buffer_stale(buf);
516 btrfs_mark_buffer_dirty(cow);
517 *cow_ret = cow;
518 return 0;
519 }
520
should_cow_block(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct extent_buffer * buf)521 static inline int should_cow_block(struct btrfs_trans_handle *trans,
522 struct btrfs_root *root,
523 struct extent_buffer *buf)
524 {
525 if (btrfs_is_testing(root->fs_info))
526 return 0;
527
528 /* Ensure we can see the FORCE_COW bit */
529 smp_mb__before_atomic();
530
531 /*
532 * We do not need to cow a block if
533 * 1) this block is not created or changed in this transaction;
534 * 2) this block does not belong to TREE_RELOC tree;
535 * 3) the root is not forced COW.
536 *
537 * What is forced COW:
538 * when we create snapshot during committing the transaction,
539 * after we've finished copying src root, we must COW the shared
540 * block to ensure the metadata consistency.
541 */
542 if (btrfs_header_generation(buf) == trans->transid &&
543 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
544 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
545 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
546 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
547 return 0;
548 return 1;
549 }
550
551 /*
552 * cows a single block, see __btrfs_cow_block for the real work.
553 * This version of it has extra checks so that a block isn't COWed more than
554 * once per transaction, as long as it hasn't been written yet
555 */
btrfs_cow_block(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct extent_buffer * buf,struct extent_buffer * parent,int parent_slot,struct extent_buffer ** cow_ret,enum btrfs_lock_nesting nest)556 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
557 struct btrfs_root *root, struct extent_buffer *buf,
558 struct extent_buffer *parent, int parent_slot,
559 struct extent_buffer **cow_ret,
560 enum btrfs_lock_nesting nest)
561 {
562 struct btrfs_fs_info *fs_info = root->fs_info;
563 u64 search_start;
564 int ret;
565
566 if (unlikely(test_bit(BTRFS_ROOT_DELETING, &root->state))) {
567 btrfs_abort_transaction(trans, -EUCLEAN);
568 btrfs_crit(fs_info,
569 "attempt to COW block %llu on root %llu that is being deleted",
570 buf->start, btrfs_root_id(root));
571 return -EUCLEAN;
572 }
573
574 /*
575 * COWing must happen through a running transaction, which always
576 * matches the current fs generation (it's a transaction with a state
577 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
578 * into error state to prevent the commit of any transaction.
579 */
580 if (unlikely(trans->transaction != fs_info->running_transaction ||
581 trans->transid != fs_info->generation)) {
582 btrfs_abort_transaction(trans, -EUCLEAN);
583 btrfs_crit(fs_info,
584 "unexpected transaction when attempting to COW block %llu on root %llu, transaction %llu running transaction %llu fs generation %llu",
585 buf->start, btrfs_root_id(root), trans->transid,
586 fs_info->running_transaction->transid,
587 fs_info->generation);
588 return -EUCLEAN;
589 }
590
591 if (!should_cow_block(trans, root, buf)) {
592 *cow_ret = buf;
593 return 0;
594 }
595
596 search_start = buf->start & ~((u64)SZ_1G - 1);
597
598 /*
599 * Before CoWing this block for later modification, check if it's
600 * the subtree root and do the delayed subtree trace if needed.
601 *
602 * Also We don't care about the error, as it's handled internally.
603 */
604 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
605 ret = __btrfs_cow_block(trans, root, buf, parent,
606 parent_slot, cow_ret, search_start, 0, nest);
607
608 trace_btrfs_cow_block(root, buf, *cow_ret);
609
610 return ret;
611 }
612 ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
613
614 /*
615 * helper function for defrag to decide if two blocks pointed to by a
616 * node are actually close by
617 */
close_blocks(u64 blocknr,u64 other,u32 blocksize)618 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
619 {
620 if (blocknr < other && other - (blocknr + blocksize) < 32768)
621 return 1;
622 if (blocknr > other && blocknr - (other + blocksize) < 32768)
623 return 1;
624 return 0;
625 }
626
627 #ifdef __LITTLE_ENDIAN
628
629 /*
630 * Compare two keys, on little-endian the disk order is same as CPU order and
631 * we can avoid the conversion.
632 */
comp_keys(const struct btrfs_disk_key * disk_key,const struct btrfs_key * k2)633 static int comp_keys(const struct btrfs_disk_key *disk_key,
634 const struct btrfs_key *k2)
635 {
636 const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
637
638 return btrfs_comp_cpu_keys(k1, k2);
639 }
640
641 #else
642
643 /*
644 * compare two keys in a memcmp fashion
645 */
comp_keys(const struct btrfs_disk_key * disk,const struct btrfs_key * k2)646 static int comp_keys(const struct btrfs_disk_key *disk,
647 const struct btrfs_key *k2)
648 {
649 struct btrfs_key k1;
650
651 btrfs_disk_key_to_cpu(&k1, disk);
652
653 return btrfs_comp_cpu_keys(&k1, k2);
654 }
655 #endif
656
657 /*
658 * same as comp_keys only with two btrfs_key's
659 */
btrfs_comp_cpu_keys(const struct btrfs_key * k1,const struct btrfs_key * k2)660 int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
661 {
662 if (k1->objectid > k2->objectid)
663 return 1;
664 if (k1->objectid < k2->objectid)
665 return -1;
666 if (k1->type > k2->type)
667 return 1;
668 if (k1->type < k2->type)
669 return -1;
670 if (k1->offset > k2->offset)
671 return 1;
672 if (k1->offset < k2->offset)
673 return -1;
674 return 0;
675 }
676
677 /*
678 * this is used by the defrag code to go through all the
679 * leaves pointed to by a node and reallocate them so that
680 * disk order is close to key order
681 */
btrfs_realloc_node(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct extent_buffer * parent,int start_slot,u64 * last_ret,struct btrfs_key * progress)682 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
683 struct btrfs_root *root, struct extent_buffer *parent,
684 int start_slot, u64 *last_ret,
685 struct btrfs_key *progress)
686 {
687 struct btrfs_fs_info *fs_info = root->fs_info;
688 struct extent_buffer *cur;
689 u64 blocknr;
690 u64 search_start = *last_ret;
691 u64 last_block = 0;
692 u64 other;
693 u32 parent_nritems;
694 int end_slot;
695 int i;
696 int err = 0;
697 u32 blocksize;
698 int progress_passed = 0;
699 struct btrfs_disk_key disk_key;
700
701 /*
702 * COWing must happen through a running transaction, which always
703 * matches the current fs generation (it's a transaction with a state
704 * less than TRANS_STATE_UNBLOCKED). If it doesn't, then turn the fs
705 * into error state to prevent the commit of any transaction.
706 */
707 if (unlikely(trans->transaction != fs_info->running_transaction ||
708 trans->transid != fs_info->generation)) {
709 btrfs_abort_transaction(trans, -EUCLEAN);
710 btrfs_crit(fs_info,
711 "unexpected transaction when attempting to reallocate parent %llu for root %llu, transaction %llu running transaction %llu fs generation %llu",
712 parent->start, btrfs_root_id(root), trans->transid,
713 fs_info->running_transaction->transid,
714 fs_info->generation);
715 return -EUCLEAN;
716 }
717
718 parent_nritems = btrfs_header_nritems(parent);
719 blocksize = fs_info->nodesize;
720 end_slot = parent_nritems - 1;
721
722 if (parent_nritems <= 1)
723 return 0;
724
725 for (i = start_slot; i <= end_slot; i++) {
726 int close = 1;
727
728 btrfs_node_key(parent, &disk_key, i);
729 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
730 continue;
731
732 progress_passed = 1;
733 blocknr = btrfs_node_blockptr(parent, i);
734 if (last_block == 0)
735 last_block = blocknr;
736
737 if (i > 0) {
738 other = btrfs_node_blockptr(parent, i - 1);
739 close = close_blocks(blocknr, other, blocksize);
740 }
741 if (!close && i < end_slot) {
742 other = btrfs_node_blockptr(parent, i + 1);
743 close = close_blocks(blocknr, other, blocksize);
744 }
745 if (close) {
746 last_block = blocknr;
747 continue;
748 }
749
750 cur = btrfs_read_node_slot(parent, i);
751 if (IS_ERR(cur))
752 return PTR_ERR(cur);
753 if (search_start == 0)
754 search_start = last_block;
755
756 btrfs_tree_lock(cur);
757 err = __btrfs_cow_block(trans, root, cur, parent, i,
758 &cur, search_start,
759 min(16 * blocksize,
760 (end_slot - i) * blocksize),
761 BTRFS_NESTING_COW);
762 if (err) {
763 btrfs_tree_unlock(cur);
764 free_extent_buffer(cur);
765 break;
766 }
767 search_start = cur->start;
768 last_block = cur->start;
769 *last_ret = search_start;
770 btrfs_tree_unlock(cur);
771 free_extent_buffer(cur);
772 }
773 return err;
774 }
775
776 /*
777 * Search for a key in the given extent_buffer.
778 *
779 * The lower boundary for the search is specified by the slot number @low. Use a
780 * value of 0 to search over the whole extent buffer.
781 *
782 * The slot in the extent buffer is returned via @slot. If the key exists in the
783 * extent buffer, then @slot will point to the slot where the key is, otherwise
784 * it points to the slot where you would insert the key.
785 *
786 * Slot may point to the total number of items (i.e. one position beyond the last
787 * key) if the key is bigger than the last key in the extent buffer.
788 */
generic_bin_search(struct extent_buffer * eb,int low,const struct btrfs_key * key,int * slot)789 static noinline int generic_bin_search(struct extent_buffer *eb, int low,
790 const struct btrfs_key *key, int *slot)
791 {
792 unsigned long p;
793 int item_size;
794 int high = btrfs_header_nritems(eb);
795 int ret;
796 const int key_size = sizeof(struct btrfs_disk_key);
797
798 if (low > high) {
799 btrfs_err(eb->fs_info,
800 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
801 __func__, low, high, eb->start,
802 btrfs_header_owner(eb), btrfs_header_level(eb));
803 return -EINVAL;
804 }
805
806 if (btrfs_header_level(eb) == 0) {
807 p = offsetof(struct btrfs_leaf, items);
808 item_size = sizeof(struct btrfs_item);
809 } else {
810 p = offsetof(struct btrfs_node, ptrs);
811 item_size = sizeof(struct btrfs_key_ptr);
812 }
813
814 while (low < high) {
815 unsigned long oip;
816 unsigned long offset;
817 struct btrfs_disk_key *tmp;
818 struct btrfs_disk_key unaligned;
819 int mid;
820
821 mid = (low + high) / 2;
822 offset = p + mid * item_size;
823 oip = offset_in_page(offset);
824
825 if (oip + key_size <= PAGE_SIZE) {
826 const unsigned long idx = get_eb_page_index(offset);
827 char *kaddr = page_address(eb->pages[idx]);
828
829 oip = get_eb_offset_in_page(eb, offset);
830 tmp = (struct btrfs_disk_key *)(kaddr + oip);
831 } else {
832 read_extent_buffer(eb, &unaligned, offset, key_size);
833 tmp = &unaligned;
834 }
835
836 ret = comp_keys(tmp, key);
837
838 if (ret < 0)
839 low = mid + 1;
840 else if (ret > 0)
841 high = mid;
842 else {
843 *slot = mid;
844 return 0;
845 }
846 }
847 *slot = low;
848 return 1;
849 }
850
851 /*
852 * Simple binary search on an extent buffer. Works for both leaves and nodes, and
853 * always searches over the whole range of keys (slot 0 to slot 'nritems - 1').
854 */
btrfs_bin_search(struct extent_buffer * eb,const struct btrfs_key * key,int * slot)855 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
856 int *slot)
857 {
858 return generic_bin_search(eb, 0, key, slot);
859 }
860
root_add_used(struct btrfs_root * root,u32 size)861 static void root_add_used(struct btrfs_root *root, u32 size)
862 {
863 spin_lock(&root->accounting_lock);
864 btrfs_set_root_used(&root->root_item,
865 btrfs_root_used(&root->root_item) + size);
866 spin_unlock(&root->accounting_lock);
867 }
868
root_sub_used(struct btrfs_root * root,u32 size)869 static void root_sub_used(struct btrfs_root *root, u32 size)
870 {
871 spin_lock(&root->accounting_lock);
872 btrfs_set_root_used(&root->root_item,
873 btrfs_root_used(&root->root_item) - size);
874 spin_unlock(&root->accounting_lock);
875 }
876
877 /* given a node and slot number, this reads the blocks it points to. The
878 * extent buffer is returned with a reference taken (but unlocked).
879 */
btrfs_read_node_slot(struct extent_buffer * parent,int slot)880 struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
881 int slot)
882 {
883 int level = btrfs_header_level(parent);
884 struct extent_buffer *eb;
885 struct btrfs_key first_key;
886
887 if (slot < 0 || slot >= btrfs_header_nritems(parent))
888 return ERR_PTR(-ENOENT);
889
890 BUG_ON(level == 0);
891
892 btrfs_node_key_to_cpu(parent, &first_key, slot);
893 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
894 btrfs_header_owner(parent),
895 btrfs_node_ptr_generation(parent, slot),
896 level - 1, &first_key);
897 if (IS_ERR(eb))
898 return eb;
899 if (!extent_buffer_uptodate(eb)) {
900 free_extent_buffer(eb);
901 return ERR_PTR(-EIO);
902 }
903
904 return eb;
905 }
906
907 /*
908 * node level balancing, used to make sure nodes are in proper order for
909 * item deletion. We balance from the top down, so we have to make sure
910 * that a deletion won't leave an node completely empty later on.
911 */
balance_level(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int level)912 static noinline int balance_level(struct btrfs_trans_handle *trans,
913 struct btrfs_root *root,
914 struct btrfs_path *path, int level)
915 {
916 struct btrfs_fs_info *fs_info = root->fs_info;
917 struct extent_buffer *right = NULL;
918 struct extent_buffer *mid;
919 struct extent_buffer *left = NULL;
920 struct extent_buffer *parent = NULL;
921 int ret = 0;
922 int wret;
923 int pslot;
924 int orig_slot = path->slots[level];
925 u64 orig_ptr;
926
927 ASSERT(level > 0);
928
929 mid = path->nodes[level];
930
931 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
932 WARN_ON(btrfs_header_generation(mid) != trans->transid);
933
934 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
935
936 if (level < BTRFS_MAX_LEVEL - 1) {
937 parent = path->nodes[level + 1];
938 pslot = path->slots[level + 1];
939 }
940
941 /*
942 * deal with the case where there is only one pointer in the root
943 * by promoting the node below to a root
944 */
945 if (!parent) {
946 struct extent_buffer *child;
947
948 if (btrfs_header_nritems(mid) != 1)
949 return 0;
950
951 /* promote the child to a root */
952 child = btrfs_read_node_slot(mid, 0);
953 if (IS_ERR(child)) {
954 ret = PTR_ERR(child);
955 btrfs_handle_fs_error(fs_info, ret, NULL);
956 goto enospc;
957 }
958
959 btrfs_tree_lock(child);
960 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
961 BTRFS_NESTING_COW);
962 if (ret) {
963 btrfs_tree_unlock(child);
964 free_extent_buffer(child);
965 goto enospc;
966 }
967
968 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
969 if (ret < 0) {
970 btrfs_tree_unlock(child);
971 free_extent_buffer(child);
972 btrfs_abort_transaction(trans, ret);
973 goto enospc;
974 }
975 rcu_assign_pointer(root->node, child);
976
977 add_root_to_dirty_list(root);
978 btrfs_tree_unlock(child);
979
980 path->locks[level] = 0;
981 path->nodes[level] = NULL;
982 btrfs_clean_tree_block(mid);
983 btrfs_tree_unlock(mid);
984 /* once for the path */
985 free_extent_buffer(mid);
986
987 root_sub_used(root, mid->len);
988 btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
989 /* once for the root ptr */
990 free_extent_buffer_stale(mid);
991 return 0;
992 }
993 if (btrfs_header_nritems(mid) >
994 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
995 return 0;
996
997 left = btrfs_read_node_slot(parent, pslot - 1);
998 if (IS_ERR(left))
999 left = NULL;
1000
1001 if (left) {
1002 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1003 wret = btrfs_cow_block(trans, root, left,
1004 parent, pslot - 1, &left,
1005 BTRFS_NESTING_LEFT_COW);
1006 if (wret) {
1007 ret = wret;
1008 goto enospc;
1009 }
1010 }
1011
1012 right = btrfs_read_node_slot(parent, pslot + 1);
1013 if (IS_ERR(right))
1014 right = NULL;
1015
1016 if (right) {
1017 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1018 wret = btrfs_cow_block(trans, root, right,
1019 parent, pslot + 1, &right,
1020 BTRFS_NESTING_RIGHT_COW);
1021 if (wret) {
1022 ret = wret;
1023 goto enospc;
1024 }
1025 }
1026
1027 /* first, try to make some room in the middle buffer */
1028 if (left) {
1029 orig_slot += btrfs_header_nritems(left);
1030 wret = push_node_left(trans, left, mid, 1);
1031 if (wret < 0)
1032 ret = wret;
1033 }
1034
1035 /*
1036 * then try to empty the right most buffer into the middle
1037 */
1038 if (right) {
1039 wret = push_node_left(trans, mid, right, 1);
1040 if (wret < 0 && wret != -ENOSPC)
1041 ret = wret;
1042 if (btrfs_header_nritems(right) == 0) {
1043 btrfs_clean_tree_block(right);
1044 btrfs_tree_unlock(right);
1045 del_ptr(root, path, level + 1, pslot + 1);
1046 root_sub_used(root, right->len);
1047 btrfs_free_tree_block(trans, btrfs_root_id(root), right,
1048 0, 1);
1049 free_extent_buffer_stale(right);
1050 right = NULL;
1051 } else {
1052 struct btrfs_disk_key right_key;
1053 btrfs_node_key(right, &right_key, 0);
1054 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1055 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1056 if (ret < 0) {
1057 btrfs_abort_transaction(trans, ret);
1058 goto enospc;
1059 }
1060 btrfs_set_node_key(parent, &right_key, pslot + 1);
1061 btrfs_mark_buffer_dirty(parent);
1062 }
1063 }
1064 if (btrfs_header_nritems(mid) == 1) {
1065 /*
1066 * we're not allowed to leave a node with one item in the
1067 * tree during a delete. A deletion from lower in the tree
1068 * could try to delete the only pointer in this node.
1069 * So, pull some keys from the left.
1070 * There has to be a left pointer at this point because
1071 * otherwise we would have pulled some pointers from the
1072 * right
1073 */
1074 if (!left) {
1075 ret = -EROFS;
1076 btrfs_handle_fs_error(fs_info, ret, NULL);
1077 goto enospc;
1078 }
1079 wret = balance_node_right(trans, mid, left);
1080 if (wret < 0) {
1081 ret = wret;
1082 goto enospc;
1083 }
1084 if (wret == 1) {
1085 wret = push_node_left(trans, left, mid, 1);
1086 if (wret < 0)
1087 ret = wret;
1088 }
1089 BUG_ON(wret == 1);
1090 }
1091 if (btrfs_header_nritems(mid) == 0) {
1092 btrfs_clean_tree_block(mid);
1093 btrfs_tree_unlock(mid);
1094 del_ptr(root, path, level + 1, pslot);
1095 root_sub_used(root, mid->len);
1096 btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
1097 free_extent_buffer_stale(mid);
1098 mid = NULL;
1099 } else {
1100 /* update the parent key to reflect our changes */
1101 struct btrfs_disk_key mid_key;
1102 btrfs_node_key(mid, &mid_key, 0);
1103 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1104 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1105 if (ret < 0) {
1106 btrfs_abort_transaction(trans, ret);
1107 goto enospc;
1108 }
1109 btrfs_set_node_key(parent, &mid_key, pslot);
1110 btrfs_mark_buffer_dirty(parent);
1111 }
1112
1113 /* update the path */
1114 if (left) {
1115 if (btrfs_header_nritems(left) > orig_slot) {
1116 atomic_inc(&left->refs);
1117 /* left was locked after cow */
1118 path->nodes[level] = left;
1119 path->slots[level + 1] -= 1;
1120 path->slots[level] = orig_slot;
1121 if (mid) {
1122 btrfs_tree_unlock(mid);
1123 free_extent_buffer(mid);
1124 }
1125 } else {
1126 orig_slot -= btrfs_header_nritems(left);
1127 path->slots[level] = orig_slot;
1128 }
1129 }
1130 /* double check we haven't messed things up */
1131 if (orig_ptr !=
1132 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1133 BUG();
1134 enospc:
1135 if (right) {
1136 btrfs_tree_unlock(right);
1137 free_extent_buffer(right);
1138 }
1139 if (left) {
1140 if (path->nodes[level] != left)
1141 btrfs_tree_unlock(left);
1142 free_extent_buffer(left);
1143 }
1144 return ret;
1145 }
1146
1147 /* Node balancing for insertion. Here we only split or push nodes around
1148 * when they are completely full. This is also done top down, so we
1149 * have to be pessimistic.
1150 */
push_nodes_for_insert(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int level)1151 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1152 struct btrfs_root *root,
1153 struct btrfs_path *path, int level)
1154 {
1155 struct btrfs_fs_info *fs_info = root->fs_info;
1156 struct extent_buffer *right = NULL;
1157 struct extent_buffer *mid;
1158 struct extent_buffer *left = NULL;
1159 struct extent_buffer *parent = NULL;
1160 int ret = 0;
1161 int wret;
1162 int pslot;
1163 int orig_slot = path->slots[level];
1164
1165 if (level == 0)
1166 return 1;
1167
1168 mid = path->nodes[level];
1169 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1170
1171 if (level < BTRFS_MAX_LEVEL - 1) {
1172 parent = path->nodes[level + 1];
1173 pslot = path->slots[level + 1];
1174 }
1175
1176 if (!parent)
1177 return 1;
1178
1179 left = btrfs_read_node_slot(parent, pslot - 1);
1180 if (IS_ERR(left))
1181 left = NULL;
1182
1183 /* first, try to make some room in the middle buffer */
1184 if (left) {
1185 u32 left_nr;
1186
1187 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1188
1189 left_nr = btrfs_header_nritems(left);
1190 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1191 wret = 1;
1192 } else {
1193 ret = btrfs_cow_block(trans, root, left, parent,
1194 pslot - 1, &left,
1195 BTRFS_NESTING_LEFT_COW);
1196 if (ret)
1197 wret = 1;
1198 else {
1199 wret = push_node_left(trans, left, mid, 0);
1200 }
1201 }
1202 if (wret < 0)
1203 ret = wret;
1204 if (wret == 0) {
1205 struct btrfs_disk_key disk_key;
1206 orig_slot += left_nr;
1207 btrfs_node_key(mid, &disk_key, 0);
1208 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1209 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1210 BUG_ON(ret < 0);
1211 btrfs_set_node_key(parent, &disk_key, pslot);
1212 btrfs_mark_buffer_dirty(parent);
1213 if (btrfs_header_nritems(left) > orig_slot) {
1214 path->nodes[level] = left;
1215 path->slots[level + 1] -= 1;
1216 path->slots[level] = orig_slot;
1217 btrfs_tree_unlock(mid);
1218 free_extent_buffer(mid);
1219 } else {
1220 orig_slot -=
1221 btrfs_header_nritems(left);
1222 path->slots[level] = orig_slot;
1223 btrfs_tree_unlock(left);
1224 free_extent_buffer(left);
1225 }
1226 return 0;
1227 }
1228 btrfs_tree_unlock(left);
1229 free_extent_buffer(left);
1230 }
1231 right = btrfs_read_node_slot(parent, pslot + 1);
1232 if (IS_ERR(right))
1233 right = NULL;
1234
1235 /*
1236 * then try to empty the right most buffer into the middle
1237 */
1238 if (right) {
1239 u32 right_nr;
1240
1241 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1242
1243 right_nr = btrfs_header_nritems(right);
1244 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1245 wret = 1;
1246 } else {
1247 ret = btrfs_cow_block(trans, root, right,
1248 parent, pslot + 1,
1249 &right, BTRFS_NESTING_RIGHT_COW);
1250 if (ret)
1251 wret = 1;
1252 else {
1253 wret = balance_node_right(trans, right, mid);
1254 }
1255 }
1256 if (wret < 0)
1257 ret = wret;
1258 if (wret == 0) {
1259 struct btrfs_disk_key disk_key;
1260
1261 btrfs_node_key(right, &disk_key, 0);
1262 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1263 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1264 BUG_ON(ret < 0);
1265 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1266 btrfs_mark_buffer_dirty(parent);
1267
1268 if (btrfs_header_nritems(mid) <= orig_slot) {
1269 path->nodes[level] = right;
1270 path->slots[level + 1] += 1;
1271 path->slots[level] = orig_slot -
1272 btrfs_header_nritems(mid);
1273 btrfs_tree_unlock(mid);
1274 free_extent_buffer(mid);
1275 } else {
1276 btrfs_tree_unlock(right);
1277 free_extent_buffer(right);
1278 }
1279 return 0;
1280 }
1281 btrfs_tree_unlock(right);
1282 free_extent_buffer(right);
1283 }
1284 return 1;
1285 }
1286
1287 /*
1288 * readahead one full node of leaves, finding things that are close
1289 * to the block in 'slot', and triggering ra on them.
1290 */
reada_for_search(struct btrfs_fs_info * fs_info,struct btrfs_path * path,int level,int slot,u64 objectid)1291 static void reada_for_search(struct btrfs_fs_info *fs_info,
1292 struct btrfs_path *path,
1293 int level, int slot, u64 objectid)
1294 {
1295 struct extent_buffer *node;
1296 struct btrfs_disk_key disk_key;
1297 u32 nritems;
1298 u64 search;
1299 u64 target;
1300 u64 nread = 0;
1301 u64 nread_max;
1302 u32 nr;
1303 u32 blocksize;
1304 u32 nscan = 0;
1305
1306 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1307 return;
1308
1309 if (!path->nodes[level])
1310 return;
1311
1312 node = path->nodes[level];
1313
1314 /*
1315 * Since the time between visiting leaves is much shorter than the time
1316 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1317 * much IO at once (possibly random).
1318 */
1319 if (path->reada == READA_FORWARD_ALWAYS) {
1320 if (level > 1)
1321 nread_max = node->fs_info->nodesize;
1322 else
1323 nread_max = SZ_128K;
1324 } else {
1325 nread_max = SZ_64K;
1326 }
1327
1328 search = btrfs_node_blockptr(node, slot);
1329 blocksize = fs_info->nodesize;
1330 if (path->reada != READA_FORWARD_ALWAYS) {
1331 struct extent_buffer *eb;
1332
1333 eb = find_extent_buffer(fs_info, search);
1334 if (eb) {
1335 free_extent_buffer(eb);
1336 return;
1337 }
1338 }
1339
1340 target = search;
1341
1342 nritems = btrfs_header_nritems(node);
1343 nr = slot;
1344
1345 while (1) {
1346 if (path->reada == READA_BACK) {
1347 if (nr == 0)
1348 break;
1349 nr--;
1350 } else if (path->reada == READA_FORWARD ||
1351 path->reada == READA_FORWARD_ALWAYS) {
1352 nr++;
1353 if (nr >= nritems)
1354 break;
1355 }
1356 if (path->reada == READA_BACK && objectid) {
1357 btrfs_node_key(node, &disk_key, nr);
1358 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1359 break;
1360 }
1361 search = btrfs_node_blockptr(node, nr);
1362 if (path->reada == READA_FORWARD_ALWAYS ||
1363 (search <= target && target - search <= 65536) ||
1364 (search > target && search - target <= 65536)) {
1365 btrfs_readahead_node_child(node, nr);
1366 nread += blocksize;
1367 }
1368 nscan++;
1369 if (nread > nread_max || nscan > 32)
1370 break;
1371 }
1372 }
1373
reada_for_balance(struct btrfs_path * path,int level)1374 static noinline void reada_for_balance(struct btrfs_path *path, int level)
1375 {
1376 struct extent_buffer *parent;
1377 int slot;
1378 int nritems;
1379
1380 parent = path->nodes[level + 1];
1381 if (!parent)
1382 return;
1383
1384 nritems = btrfs_header_nritems(parent);
1385 slot = path->slots[level + 1];
1386
1387 if (slot > 0)
1388 btrfs_readahead_node_child(parent, slot - 1);
1389 if (slot + 1 < nritems)
1390 btrfs_readahead_node_child(parent, slot + 1);
1391 }
1392
1393
1394 /*
1395 * when we walk down the tree, it is usually safe to unlock the higher layers
1396 * in the tree. The exceptions are when our path goes through slot 0, because
1397 * operations on the tree might require changing key pointers higher up in the
1398 * tree.
1399 *
1400 * callers might also have set path->keep_locks, which tells this code to keep
1401 * the lock if the path points to the last slot in the block. This is part of
1402 * walking through the tree, and selecting the next slot in the higher block.
1403 *
1404 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1405 * if lowest_unlock is 1, level 0 won't be unlocked
1406 */
unlock_up(struct btrfs_path * path,int level,int lowest_unlock,int min_write_lock_level,int * write_lock_level)1407 static noinline void unlock_up(struct btrfs_path *path, int level,
1408 int lowest_unlock, int min_write_lock_level,
1409 int *write_lock_level)
1410 {
1411 int i;
1412 int skip_level = level;
1413 bool check_skip = true;
1414
1415 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1416 if (!path->nodes[i])
1417 break;
1418 if (!path->locks[i])
1419 break;
1420
1421 if (check_skip) {
1422 if (path->slots[i] == 0) {
1423 skip_level = i + 1;
1424 continue;
1425 }
1426
1427 if (path->keep_locks) {
1428 u32 nritems;
1429
1430 nritems = btrfs_header_nritems(path->nodes[i]);
1431 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1432 skip_level = i + 1;
1433 continue;
1434 }
1435 }
1436 }
1437
1438 if (i >= lowest_unlock && i > skip_level) {
1439 check_skip = false;
1440 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
1441 path->locks[i] = 0;
1442 if (write_lock_level &&
1443 i > min_write_lock_level &&
1444 i <= *write_lock_level) {
1445 *write_lock_level = i - 1;
1446 }
1447 }
1448 }
1449 }
1450
1451 /*
1452 * Helper function for btrfs_search_slot() and other functions that do a search
1453 * on a btree. The goal is to find a tree block in the cache (the radix tree at
1454 * fs_info->buffer_radix), but if we can't find it, or it's not up to date, read
1455 * its pages from disk.
1456 *
1457 * Returns -EAGAIN, with the path unlocked, if the caller needs to repeat the
1458 * whole btree search, starting again from the current root node.
1459 */
1460 static int
read_block_for_search(struct btrfs_root * root,struct btrfs_path * p,struct extent_buffer ** eb_ret,int level,int slot,const struct btrfs_key * key)1461 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1462 struct extent_buffer **eb_ret, int level, int slot,
1463 const struct btrfs_key *key)
1464 {
1465 struct btrfs_fs_info *fs_info = root->fs_info;
1466 u64 blocknr;
1467 u64 gen;
1468 struct extent_buffer *tmp;
1469 struct btrfs_key first_key;
1470 int ret;
1471 int parent_level;
1472 bool unlock_up;
1473
1474 unlock_up = ((level + 1 < BTRFS_MAX_LEVEL) && p->locks[level + 1]);
1475 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1476 gen = btrfs_node_ptr_generation(*eb_ret, slot);
1477 parent_level = btrfs_header_level(*eb_ret);
1478 btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
1479
1480 /*
1481 * If we need to read an extent buffer from disk and we are holding locks
1482 * on upper level nodes, we unlock all the upper nodes before reading the
1483 * extent buffer, and then return -EAGAIN to the caller as it needs to
1484 * restart the search. We don't release the lock on the current level
1485 * because we need to walk this node to figure out which blocks to read.
1486 */
1487 tmp = find_extent_buffer(fs_info, blocknr);
1488 if (tmp) {
1489 if (p->reada == READA_FORWARD_ALWAYS)
1490 reada_for_search(fs_info, p, level, slot, key->objectid);
1491
1492 /* first we do an atomic uptodate check */
1493 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
1494 /*
1495 * Do extra check for first_key, eb can be stale due to
1496 * being cached, read from scrub, or have multiple
1497 * parents (shared tree blocks).
1498 */
1499 if (btrfs_verify_level_key(tmp,
1500 parent_level - 1, &first_key, gen)) {
1501 free_extent_buffer(tmp);
1502 return -EUCLEAN;
1503 }
1504 *eb_ret = tmp;
1505 return 0;
1506 }
1507
1508 if (p->nowait) {
1509 free_extent_buffer(tmp);
1510 return -EAGAIN;
1511 }
1512
1513 if (unlock_up)
1514 btrfs_unlock_up_safe(p, level + 1);
1515
1516 /* now we're allowed to do a blocking uptodate check */
1517 ret = btrfs_read_extent_buffer(tmp, gen, parent_level - 1, &first_key);
1518 if (ret) {
1519 free_extent_buffer(tmp);
1520 btrfs_release_path(p);
1521 return -EIO;
1522 }
1523 if (btrfs_check_eb_owner(tmp, root->root_key.objectid)) {
1524 free_extent_buffer(tmp);
1525 btrfs_release_path(p);
1526 return -EUCLEAN;
1527 }
1528
1529 if (unlock_up)
1530 ret = -EAGAIN;
1531
1532 goto out;
1533 } else if (p->nowait) {
1534 return -EAGAIN;
1535 }
1536
1537 if (unlock_up) {
1538 btrfs_unlock_up_safe(p, level + 1);
1539 ret = -EAGAIN;
1540 } else {
1541 ret = 0;
1542 }
1543
1544 if (p->reada != READA_NONE)
1545 reada_for_search(fs_info, p, level, slot, key->objectid);
1546
1547 tmp = read_tree_block(fs_info, blocknr, root->root_key.objectid,
1548 gen, parent_level - 1, &first_key);
1549 if (IS_ERR(tmp)) {
1550 btrfs_release_path(p);
1551 return PTR_ERR(tmp);
1552 }
1553 /*
1554 * If the read above didn't mark this buffer up to date,
1555 * it will never end up being up to date. Set ret to EIO now
1556 * and give up so that our caller doesn't loop forever
1557 * on our EAGAINs.
1558 */
1559 if (!extent_buffer_uptodate(tmp))
1560 ret = -EIO;
1561
1562 out:
1563 if (ret == 0) {
1564 *eb_ret = tmp;
1565 } else {
1566 free_extent_buffer(tmp);
1567 btrfs_release_path(p);
1568 }
1569
1570 return ret;
1571 }
1572
1573 /*
1574 * helper function for btrfs_search_slot. This does all of the checks
1575 * for node-level blocks and does any balancing required based on
1576 * the ins_len.
1577 *
1578 * If no extra work was required, zero is returned. If we had to
1579 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1580 * start over
1581 */
1582 static int
setup_nodes_for_search(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * p,struct extent_buffer * b,int level,int ins_len,int * write_lock_level)1583 setup_nodes_for_search(struct btrfs_trans_handle *trans,
1584 struct btrfs_root *root, struct btrfs_path *p,
1585 struct extent_buffer *b, int level, int ins_len,
1586 int *write_lock_level)
1587 {
1588 struct btrfs_fs_info *fs_info = root->fs_info;
1589 int ret = 0;
1590
1591 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1592 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1593
1594 if (*write_lock_level < level + 1) {
1595 *write_lock_level = level + 1;
1596 btrfs_release_path(p);
1597 return -EAGAIN;
1598 }
1599
1600 reada_for_balance(p, level);
1601 ret = split_node(trans, root, p, level);
1602
1603 b = p->nodes[level];
1604 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1605 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1606
1607 if (*write_lock_level < level + 1) {
1608 *write_lock_level = level + 1;
1609 btrfs_release_path(p);
1610 return -EAGAIN;
1611 }
1612
1613 reada_for_balance(p, level);
1614 ret = balance_level(trans, root, p, level);
1615 if (ret)
1616 return ret;
1617
1618 b = p->nodes[level];
1619 if (!b) {
1620 btrfs_release_path(p);
1621 return -EAGAIN;
1622 }
1623 BUG_ON(btrfs_header_nritems(b) == 1);
1624 }
1625 return ret;
1626 }
1627
btrfs_find_item(struct btrfs_root * fs_root,struct btrfs_path * path,u64 iobjectid,u64 ioff,u8 key_type,struct btrfs_key * found_key)1628 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1629 u64 iobjectid, u64 ioff, u8 key_type,
1630 struct btrfs_key *found_key)
1631 {
1632 int ret;
1633 struct btrfs_key key;
1634 struct extent_buffer *eb;
1635
1636 ASSERT(path);
1637 ASSERT(found_key);
1638
1639 key.type = key_type;
1640 key.objectid = iobjectid;
1641 key.offset = ioff;
1642
1643 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1644 if (ret < 0)
1645 return ret;
1646
1647 eb = path->nodes[0];
1648 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1649 ret = btrfs_next_leaf(fs_root, path);
1650 if (ret)
1651 return ret;
1652 eb = path->nodes[0];
1653 }
1654
1655 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1656 if (found_key->type != key.type ||
1657 found_key->objectid != key.objectid)
1658 return 1;
1659
1660 return 0;
1661 }
1662
btrfs_search_slot_get_root(struct btrfs_root * root,struct btrfs_path * p,int write_lock_level)1663 static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1664 struct btrfs_path *p,
1665 int write_lock_level)
1666 {
1667 struct extent_buffer *b;
1668 int root_lock = 0;
1669 int level = 0;
1670
1671 if (p->search_commit_root) {
1672 b = root->commit_root;
1673 atomic_inc(&b->refs);
1674 level = btrfs_header_level(b);
1675 /*
1676 * Ensure that all callers have set skip_locking when
1677 * p->search_commit_root = 1.
1678 */
1679 ASSERT(p->skip_locking == 1);
1680
1681 goto out;
1682 }
1683
1684 if (p->skip_locking) {
1685 b = btrfs_root_node(root);
1686 level = btrfs_header_level(b);
1687 goto out;
1688 }
1689
1690 /* We try very hard to do read locks on the root */
1691 root_lock = BTRFS_READ_LOCK;
1692
1693 /*
1694 * If the level is set to maximum, we can skip trying to get the read
1695 * lock.
1696 */
1697 if (write_lock_level < BTRFS_MAX_LEVEL) {
1698 /*
1699 * We don't know the level of the root node until we actually
1700 * have it read locked
1701 */
1702 if (p->nowait) {
1703 b = btrfs_try_read_lock_root_node(root);
1704 if (IS_ERR(b))
1705 return b;
1706 } else {
1707 b = btrfs_read_lock_root_node(root);
1708 }
1709 level = btrfs_header_level(b);
1710 if (level > write_lock_level)
1711 goto out;
1712
1713 /* Whoops, must trade for write lock */
1714 btrfs_tree_read_unlock(b);
1715 free_extent_buffer(b);
1716 }
1717
1718 b = btrfs_lock_root_node(root);
1719 root_lock = BTRFS_WRITE_LOCK;
1720
1721 /* The level might have changed, check again */
1722 level = btrfs_header_level(b);
1723
1724 out:
1725 /*
1726 * The root may have failed to write out at some point, and thus is no
1727 * longer valid, return an error in this case.
1728 */
1729 if (!extent_buffer_uptodate(b)) {
1730 if (root_lock)
1731 btrfs_tree_unlock_rw(b, root_lock);
1732 free_extent_buffer(b);
1733 return ERR_PTR(-EIO);
1734 }
1735
1736 p->nodes[level] = b;
1737 if (!p->skip_locking)
1738 p->locks[level] = root_lock;
1739 /*
1740 * Callers are responsible for dropping b's references.
1741 */
1742 return b;
1743 }
1744
1745 /*
1746 * Replace the extent buffer at the lowest level of the path with a cloned
1747 * version. The purpose is to be able to use it safely, after releasing the
1748 * commit root semaphore, even if relocation is happening in parallel, the
1749 * transaction used for relocation is committed and the extent buffer is
1750 * reallocated in the next transaction.
1751 *
1752 * This is used in a context where the caller does not prevent transaction
1753 * commits from happening, either by holding a transaction handle or holding
1754 * some lock, while it's doing searches through a commit root.
1755 * At the moment it's only used for send operations.
1756 */
finish_need_commit_sem_search(struct btrfs_path * path)1757 static int finish_need_commit_sem_search(struct btrfs_path *path)
1758 {
1759 const int i = path->lowest_level;
1760 const int slot = path->slots[i];
1761 struct extent_buffer *lowest = path->nodes[i];
1762 struct extent_buffer *clone;
1763
1764 ASSERT(path->need_commit_sem);
1765
1766 if (!lowest)
1767 return 0;
1768
1769 lockdep_assert_held_read(&lowest->fs_info->commit_root_sem);
1770
1771 clone = btrfs_clone_extent_buffer(lowest);
1772 if (!clone)
1773 return -ENOMEM;
1774
1775 btrfs_release_path(path);
1776 path->nodes[i] = clone;
1777 path->slots[i] = slot;
1778
1779 return 0;
1780 }
1781
search_for_key_slot(struct extent_buffer * eb,int search_low_slot,const struct btrfs_key * key,int prev_cmp,int * slot)1782 static inline int search_for_key_slot(struct extent_buffer *eb,
1783 int search_low_slot,
1784 const struct btrfs_key *key,
1785 int prev_cmp,
1786 int *slot)
1787 {
1788 /*
1789 * If a previous call to btrfs_bin_search() on a parent node returned an
1790 * exact match (prev_cmp == 0), we can safely assume the target key will
1791 * always be at slot 0 on lower levels, since each key pointer
1792 * (struct btrfs_key_ptr) refers to the lowest key accessible from the
1793 * subtree it points to. Thus we can skip searching lower levels.
1794 */
1795 if (prev_cmp == 0) {
1796 *slot = 0;
1797 return 0;
1798 }
1799
1800 return generic_bin_search(eb, search_low_slot, key, slot);
1801 }
1802
search_leaf(struct btrfs_trans_handle * trans,struct btrfs_root * root,const struct btrfs_key * key,struct btrfs_path * path,int ins_len,int prev_cmp)1803 static int search_leaf(struct btrfs_trans_handle *trans,
1804 struct btrfs_root *root,
1805 const struct btrfs_key *key,
1806 struct btrfs_path *path,
1807 int ins_len,
1808 int prev_cmp)
1809 {
1810 struct extent_buffer *leaf = path->nodes[0];
1811 int leaf_free_space = -1;
1812 int search_low_slot = 0;
1813 int ret;
1814 bool do_bin_search = true;
1815
1816 /*
1817 * If we are doing an insertion, the leaf has enough free space and the
1818 * destination slot for the key is not slot 0, then we can unlock our
1819 * write lock on the parent, and any other upper nodes, before doing the
1820 * binary search on the leaf (with search_for_key_slot()), allowing other
1821 * tasks to lock the parent and any other upper nodes.
1822 */
1823 if (ins_len > 0) {
1824 /*
1825 * Cache the leaf free space, since we will need it later and it
1826 * will not change until then.
1827 */
1828 leaf_free_space = btrfs_leaf_free_space(leaf);
1829
1830 /*
1831 * !path->locks[1] means we have a single node tree, the leaf is
1832 * the root of the tree.
1833 */
1834 if (path->locks[1] && leaf_free_space >= ins_len) {
1835 struct btrfs_disk_key first_key;
1836
1837 ASSERT(btrfs_header_nritems(leaf) > 0);
1838 btrfs_item_key(leaf, &first_key, 0);
1839
1840 /*
1841 * Doing the extra comparison with the first key is cheap,
1842 * taking into account that the first key is very likely
1843 * already in a cache line because it immediately follows
1844 * the extent buffer's header and we have recently accessed
1845 * the header's level field.
1846 */
1847 ret = comp_keys(&first_key, key);
1848 if (ret < 0) {
1849 /*
1850 * The first key is smaller than the key we want
1851 * to insert, so we are safe to unlock all upper
1852 * nodes and we have to do the binary search.
1853 *
1854 * We do use btrfs_unlock_up_safe() and not
1855 * unlock_up() because the later does not unlock
1856 * nodes with a slot of 0 - we can safely unlock
1857 * any node even if its slot is 0 since in this
1858 * case the key does not end up at slot 0 of the
1859 * leaf and there's no need to split the leaf.
1860 */
1861 btrfs_unlock_up_safe(path, 1);
1862 search_low_slot = 1;
1863 } else {
1864 /*
1865 * The first key is >= then the key we want to
1866 * insert, so we can skip the binary search as
1867 * the target key will be at slot 0.
1868 *
1869 * We can not unlock upper nodes when the key is
1870 * less than the first key, because we will need
1871 * to update the key at slot 0 of the parent node
1872 * and possibly of other upper nodes too.
1873 * If the key matches the first key, then we can
1874 * unlock all the upper nodes, using
1875 * btrfs_unlock_up_safe() instead of unlock_up()
1876 * as stated above.
1877 */
1878 if (ret == 0)
1879 btrfs_unlock_up_safe(path, 1);
1880 /*
1881 * ret is already 0 or 1, matching the result of
1882 * a btrfs_bin_search() call, so there is no need
1883 * to adjust it.
1884 */
1885 do_bin_search = false;
1886 path->slots[0] = 0;
1887 }
1888 }
1889 }
1890
1891 if (do_bin_search) {
1892 ret = search_for_key_slot(leaf, search_low_slot, key,
1893 prev_cmp, &path->slots[0]);
1894 if (ret < 0)
1895 return ret;
1896 }
1897
1898 if (ins_len > 0) {
1899 /*
1900 * Item key already exists. In this case, if we are allowed to
1901 * insert the item (for example, in dir_item case, item key
1902 * collision is allowed), it will be merged with the original
1903 * item. Only the item size grows, no new btrfs item will be
1904 * added. If search_for_extension is not set, ins_len already
1905 * accounts the size btrfs_item, deduct it here so leaf space
1906 * check will be correct.
1907 */
1908 if (ret == 0 && !path->search_for_extension) {
1909 ASSERT(ins_len >= sizeof(struct btrfs_item));
1910 ins_len -= sizeof(struct btrfs_item);
1911 }
1912
1913 ASSERT(leaf_free_space >= 0);
1914
1915 if (leaf_free_space < ins_len) {
1916 int err;
1917
1918 err = split_leaf(trans, root, key, path, ins_len,
1919 (ret == 0));
1920 ASSERT(err <= 0);
1921 if (WARN_ON(err > 0))
1922 err = -EUCLEAN;
1923 if (err)
1924 ret = err;
1925 }
1926 }
1927
1928 return ret;
1929 }
1930
1931 /*
1932 * btrfs_search_slot - look for a key in a tree and perform necessary
1933 * modifications to preserve tree invariants.
1934 *
1935 * @trans: Handle of transaction, used when modifying the tree
1936 * @p: Holds all btree nodes along the search path
1937 * @root: The root node of the tree
1938 * @key: The key we are looking for
1939 * @ins_len: Indicates purpose of search:
1940 * >0 for inserts it's size of item inserted (*)
1941 * <0 for deletions
1942 * 0 for plain searches, not modifying the tree
1943 *
1944 * (*) If size of item inserted doesn't include
1945 * sizeof(struct btrfs_item), then p->search_for_extension must
1946 * be set.
1947 * @cow: boolean should CoW operations be performed. Must always be 1
1948 * when modifying the tree.
1949 *
1950 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
1951 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
1952 *
1953 * If @key is found, 0 is returned and you can find the item in the leaf level
1954 * of the path (level 0)
1955 *
1956 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
1957 * points to the slot where it should be inserted
1958 *
1959 * If an error is encountered while searching the tree a negative error number
1960 * is returned
1961 */
btrfs_search_slot(struct btrfs_trans_handle * trans,struct btrfs_root * root,const struct btrfs_key * key,struct btrfs_path * p,int ins_len,int cow)1962 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1963 const struct btrfs_key *key, struct btrfs_path *p,
1964 int ins_len, int cow)
1965 {
1966 struct btrfs_fs_info *fs_info = root->fs_info;
1967 struct extent_buffer *b;
1968 int slot;
1969 int ret;
1970 int err;
1971 int level;
1972 int lowest_unlock = 1;
1973 /* everything at write_lock_level or lower must be write locked */
1974 int write_lock_level = 0;
1975 u8 lowest_level = 0;
1976 int min_write_lock_level;
1977 int prev_cmp;
1978
1979 lowest_level = p->lowest_level;
1980 WARN_ON(lowest_level && ins_len > 0);
1981 WARN_ON(p->nodes[0] != NULL);
1982 BUG_ON(!cow && ins_len);
1983
1984 /*
1985 * For now only allow nowait for read only operations. There's no
1986 * strict reason why we can't, we just only need it for reads so it's
1987 * only implemented for reads.
1988 */
1989 ASSERT(!p->nowait || !cow);
1990
1991 if (ins_len < 0) {
1992 lowest_unlock = 2;
1993
1994 /* when we are removing items, we might have to go up to level
1995 * two as we update tree pointers Make sure we keep write
1996 * for those levels as well
1997 */
1998 write_lock_level = 2;
1999 } else if (ins_len > 0) {
2000 /*
2001 * for inserting items, make sure we have a write lock on
2002 * level 1 so we can update keys
2003 */
2004 write_lock_level = 1;
2005 }
2006
2007 if (!cow)
2008 write_lock_level = -1;
2009
2010 if (cow && (p->keep_locks || p->lowest_level))
2011 write_lock_level = BTRFS_MAX_LEVEL;
2012
2013 min_write_lock_level = write_lock_level;
2014
2015 if (p->need_commit_sem) {
2016 ASSERT(p->search_commit_root);
2017 if (p->nowait) {
2018 if (!down_read_trylock(&fs_info->commit_root_sem))
2019 return -EAGAIN;
2020 } else {
2021 down_read(&fs_info->commit_root_sem);
2022 }
2023 }
2024
2025 again:
2026 prev_cmp = -1;
2027 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2028 if (IS_ERR(b)) {
2029 ret = PTR_ERR(b);
2030 goto done;
2031 }
2032
2033 while (b) {
2034 int dec = 0;
2035
2036 level = btrfs_header_level(b);
2037
2038 if (cow) {
2039 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2040
2041 /*
2042 * if we don't really need to cow this block
2043 * then we don't want to set the path blocking,
2044 * so we test it here
2045 */
2046 if (!should_cow_block(trans, root, b))
2047 goto cow_done;
2048
2049 /*
2050 * must have write locks on this node and the
2051 * parent
2052 */
2053 if (level > write_lock_level ||
2054 (level + 1 > write_lock_level &&
2055 level + 1 < BTRFS_MAX_LEVEL &&
2056 p->nodes[level + 1])) {
2057 write_lock_level = level + 1;
2058 btrfs_release_path(p);
2059 goto again;
2060 }
2061
2062 if (last_level)
2063 err = btrfs_cow_block(trans, root, b, NULL, 0,
2064 &b,
2065 BTRFS_NESTING_COW);
2066 else
2067 err = btrfs_cow_block(trans, root, b,
2068 p->nodes[level + 1],
2069 p->slots[level + 1], &b,
2070 BTRFS_NESTING_COW);
2071 if (err) {
2072 ret = err;
2073 goto done;
2074 }
2075 }
2076 cow_done:
2077 p->nodes[level] = b;
2078
2079 /*
2080 * we have a lock on b and as long as we aren't changing
2081 * the tree, there is no way to for the items in b to change.
2082 * It is safe to drop the lock on our parent before we
2083 * go through the expensive btree search on b.
2084 *
2085 * If we're inserting or deleting (ins_len != 0), then we might
2086 * be changing slot zero, which may require changing the parent.
2087 * So, we can't drop the lock until after we know which slot
2088 * we're operating on.
2089 */
2090 if (!ins_len && !p->keep_locks) {
2091 int u = level + 1;
2092
2093 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2094 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2095 p->locks[u] = 0;
2096 }
2097 }
2098
2099 if (level == 0) {
2100 if (ins_len > 0)
2101 ASSERT(write_lock_level >= 1);
2102
2103 ret = search_leaf(trans, root, key, p, ins_len, prev_cmp);
2104 if (!p->search_for_split)
2105 unlock_up(p, level, lowest_unlock,
2106 min_write_lock_level, NULL);
2107 goto done;
2108 }
2109
2110 ret = search_for_key_slot(b, 0, key, prev_cmp, &slot);
2111 if (ret < 0)
2112 goto done;
2113 prev_cmp = ret;
2114
2115 if (ret && slot > 0) {
2116 dec = 1;
2117 slot--;
2118 }
2119 p->slots[level] = slot;
2120 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2121 &write_lock_level);
2122 if (err == -EAGAIN)
2123 goto again;
2124 if (err) {
2125 ret = err;
2126 goto done;
2127 }
2128 b = p->nodes[level];
2129 slot = p->slots[level];
2130
2131 /*
2132 * Slot 0 is special, if we change the key we have to update
2133 * the parent pointer which means we must have a write lock on
2134 * the parent
2135 */
2136 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2137 write_lock_level = level + 1;
2138 btrfs_release_path(p);
2139 goto again;
2140 }
2141
2142 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2143 &write_lock_level);
2144
2145 if (level == lowest_level) {
2146 if (dec)
2147 p->slots[level]++;
2148 goto done;
2149 }
2150
2151 err = read_block_for_search(root, p, &b, level, slot, key);
2152 if (err == -EAGAIN)
2153 goto again;
2154 if (err) {
2155 ret = err;
2156 goto done;
2157 }
2158
2159 if (!p->skip_locking) {
2160 level = btrfs_header_level(b);
2161
2162 btrfs_maybe_reset_lockdep_class(root, b);
2163
2164 if (level <= write_lock_level) {
2165 btrfs_tree_lock(b);
2166 p->locks[level] = BTRFS_WRITE_LOCK;
2167 } else {
2168 if (p->nowait) {
2169 if (!btrfs_try_tree_read_lock(b)) {
2170 free_extent_buffer(b);
2171 ret = -EAGAIN;
2172 goto done;
2173 }
2174 } else {
2175 btrfs_tree_read_lock(b);
2176 }
2177 p->locks[level] = BTRFS_READ_LOCK;
2178 }
2179 p->nodes[level] = b;
2180 }
2181 }
2182 ret = 1;
2183 done:
2184 if (ret < 0 && !p->skip_release_on_error)
2185 btrfs_release_path(p);
2186
2187 if (p->need_commit_sem) {
2188 int ret2;
2189
2190 ret2 = finish_need_commit_sem_search(p);
2191 up_read(&fs_info->commit_root_sem);
2192 if (ret2)
2193 ret = ret2;
2194 }
2195
2196 return ret;
2197 }
2198 ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
2199
2200 /*
2201 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2202 * current state of the tree together with the operations recorded in the tree
2203 * modification log to search for the key in a previous version of this tree, as
2204 * denoted by the time_seq parameter.
2205 *
2206 * Naturally, there is no support for insert, delete or cow operations.
2207 *
2208 * The resulting path and return value will be set up as if we called
2209 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2210 */
btrfs_search_old_slot(struct btrfs_root * root,const struct btrfs_key * key,struct btrfs_path * p,u64 time_seq)2211 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2212 struct btrfs_path *p, u64 time_seq)
2213 {
2214 struct btrfs_fs_info *fs_info = root->fs_info;
2215 struct extent_buffer *b;
2216 int slot;
2217 int ret;
2218 int err;
2219 int level;
2220 int lowest_unlock = 1;
2221 u8 lowest_level = 0;
2222
2223 lowest_level = p->lowest_level;
2224 WARN_ON(p->nodes[0] != NULL);
2225 ASSERT(!p->nowait);
2226
2227 if (p->search_commit_root) {
2228 BUG_ON(time_seq);
2229 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2230 }
2231
2232 again:
2233 b = btrfs_get_old_root(root, time_seq);
2234 if (!b) {
2235 ret = -EIO;
2236 goto done;
2237 }
2238 level = btrfs_header_level(b);
2239 p->locks[level] = BTRFS_READ_LOCK;
2240
2241 while (b) {
2242 int dec = 0;
2243
2244 level = btrfs_header_level(b);
2245 p->nodes[level] = b;
2246
2247 /*
2248 * we have a lock on b and as long as we aren't changing
2249 * the tree, there is no way to for the items in b to change.
2250 * It is safe to drop the lock on our parent before we
2251 * go through the expensive btree search on b.
2252 */
2253 btrfs_unlock_up_safe(p, level + 1);
2254
2255 ret = btrfs_bin_search(b, key, &slot);
2256 if (ret < 0)
2257 goto done;
2258
2259 if (level == 0) {
2260 p->slots[level] = slot;
2261 unlock_up(p, level, lowest_unlock, 0, NULL);
2262 goto done;
2263 }
2264
2265 if (ret && slot > 0) {
2266 dec = 1;
2267 slot--;
2268 }
2269 p->slots[level] = slot;
2270 unlock_up(p, level, lowest_unlock, 0, NULL);
2271
2272 if (level == lowest_level) {
2273 if (dec)
2274 p->slots[level]++;
2275 goto done;
2276 }
2277
2278 err = read_block_for_search(root, p, &b, level, slot, key);
2279 if (err == -EAGAIN)
2280 goto again;
2281 if (err) {
2282 ret = err;
2283 goto done;
2284 }
2285
2286 level = btrfs_header_level(b);
2287 btrfs_tree_read_lock(b);
2288 b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
2289 if (!b) {
2290 ret = -ENOMEM;
2291 goto done;
2292 }
2293 p->locks[level] = BTRFS_READ_LOCK;
2294 p->nodes[level] = b;
2295 }
2296 ret = 1;
2297 done:
2298 if (ret < 0)
2299 btrfs_release_path(p);
2300
2301 return ret;
2302 }
2303
2304 /*
2305 * helper to use instead of search slot if no exact match is needed but
2306 * instead the next or previous item should be returned.
2307 * When find_higher is true, the next higher item is returned, the next lower
2308 * otherwise.
2309 * When return_any and find_higher are both true, and no higher item is found,
2310 * return the next lower instead.
2311 * When return_any is true and find_higher is false, and no lower item is found,
2312 * return the next higher instead.
2313 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2314 * < 0 on error
2315 */
btrfs_search_slot_for_read(struct btrfs_root * root,const struct btrfs_key * key,struct btrfs_path * p,int find_higher,int return_any)2316 int btrfs_search_slot_for_read(struct btrfs_root *root,
2317 const struct btrfs_key *key,
2318 struct btrfs_path *p, int find_higher,
2319 int return_any)
2320 {
2321 int ret;
2322 struct extent_buffer *leaf;
2323
2324 again:
2325 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2326 if (ret <= 0)
2327 return ret;
2328 /*
2329 * a return value of 1 means the path is at the position where the
2330 * item should be inserted. Normally this is the next bigger item,
2331 * but in case the previous item is the last in a leaf, path points
2332 * to the first free slot in the previous leaf, i.e. at an invalid
2333 * item.
2334 */
2335 leaf = p->nodes[0];
2336
2337 if (find_higher) {
2338 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2339 ret = btrfs_next_leaf(root, p);
2340 if (ret <= 0)
2341 return ret;
2342 if (!return_any)
2343 return 1;
2344 /*
2345 * no higher item found, return the next
2346 * lower instead
2347 */
2348 return_any = 0;
2349 find_higher = 0;
2350 btrfs_release_path(p);
2351 goto again;
2352 }
2353 } else {
2354 if (p->slots[0] == 0) {
2355 ret = btrfs_prev_leaf(root, p);
2356 if (ret < 0)
2357 return ret;
2358 if (!ret) {
2359 leaf = p->nodes[0];
2360 if (p->slots[0] == btrfs_header_nritems(leaf))
2361 p->slots[0]--;
2362 return 0;
2363 }
2364 if (!return_any)
2365 return 1;
2366 /*
2367 * no lower item found, return the next
2368 * higher instead
2369 */
2370 return_any = 0;
2371 find_higher = 1;
2372 btrfs_release_path(p);
2373 goto again;
2374 } else {
2375 --p->slots[0];
2376 }
2377 }
2378 return 0;
2379 }
2380
2381 /*
2382 * Execute search and call btrfs_previous_item to traverse backwards if the item
2383 * was not found.
2384 *
2385 * Return 0 if found, 1 if not found and < 0 if error.
2386 */
btrfs_search_backwards(struct btrfs_root * root,struct btrfs_key * key,struct btrfs_path * path)2387 int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2388 struct btrfs_path *path)
2389 {
2390 int ret;
2391
2392 ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2393 if (ret > 0)
2394 ret = btrfs_previous_item(root, path, key->objectid, key->type);
2395
2396 if (ret == 0)
2397 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2398
2399 return ret;
2400 }
2401
2402 /**
2403 * Search for a valid slot for the given path.
2404 *
2405 * @root: The root node of the tree.
2406 * @key: Will contain a valid item if found.
2407 * @path: The starting point to validate the slot.
2408 *
2409 * Return: 0 if the item is valid
2410 * 1 if not found
2411 * <0 if error.
2412 */
btrfs_get_next_valid_item(struct btrfs_root * root,struct btrfs_key * key,struct btrfs_path * path)2413 int btrfs_get_next_valid_item(struct btrfs_root *root, struct btrfs_key *key,
2414 struct btrfs_path *path)
2415 {
2416 while (1) {
2417 int ret;
2418 const int slot = path->slots[0];
2419 const struct extent_buffer *leaf = path->nodes[0];
2420
2421 /* This is where we start walking the path. */
2422 if (slot >= btrfs_header_nritems(leaf)) {
2423 /*
2424 * If we've reached the last slot in this leaf we need
2425 * to go to the next leaf and reset the path.
2426 */
2427 ret = btrfs_next_leaf(root, path);
2428 if (ret)
2429 return ret;
2430 continue;
2431 }
2432 /* Store the found, valid item in @key. */
2433 btrfs_item_key_to_cpu(leaf, key, slot);
2434 break;
2435 }
2436 return 0;
2437 }
2438
2439 /*
2440 * adjust the pointers going up the tree, starting at level
2441 * making sure the right key of each node is points to 'key'.
2442 * This is used after shifting pointers to the left, so it stops
2443 * fixing up pointers when a given leaf/node is not in slot 0 of the
2444 * higher levels
2445 *
2446 */
fixup_low_keys(struct btrfs_path * path,struct btrfs_disk_key * key,int level)2447 static void fixup_low_keys(struct btrfs_path *path,
2448 struct btrfs_disk_key *key, int level)
2449 {
2450 int i;
2451 struct extent_buffer *t;
2452 int ret;
2453
2454 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2455 int tslot = path->slots[i];
2456
2457 if (!path->nodes[i])
2458 break;
2459 t = path->nodes[i];
2460 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2461 BTRFS_MOD_LOG_KEY_REPLACE, GFP_ATOMIC);
2462 BUG_ON(ret < 0);
2463 btrfs_set_node_key(t, key, tslot);
2464 btrfs_mark_buffer_dirty(path->nodes[i]);
2465 if (tslot != 0)
2466 break;
2467 }
2468 }
2469
2470 /*
2471 * update item key.
2472 *
2473 * This function isn't completely safe. It's the caller's responsibility
2474 * that the new key won't break the order
2475 */
btrfs_set_item_key_safe(struct btrfs_fs_info * fs_info,struct btrfs_path * path,const struct btrfs_key * new_key)2476 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
2477 struct btrfs_path *path,
2478 const struct btrfs_key *new_key)
2479 {
2480 struct btrfs_disk_key disk_key;
2481 struct extent_buffer *eb;
2482 int slot;
2483
2484 eb = path->nodes[0];
2485 slot = path->slots[0];
2486 if (slot > 0) {
2487 btrfs_item_key(eb, &disk_key, slot - 1);
2488 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
2489 btrfs_crit(fs_info,
2490 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2491 slot, btrfs_disk_key_objectid(&disk_key),
2492 btrfs_disk_key_type(&disk_key),
2493 btrfs_disk_key_offset(&disk_key),
2494 new_key->objectid, new_key->type,
2495 new_key->offset);
2496 btrfs_print_leaf(eb);
2497 BUG();
2498 }
2499 }
2500 if (slot < btrfs_header_nritems(eb) - 1) {
2501 btrfs_item_key(eb, &disk_key, slot + 1);
2502 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
2503 btrfs_crit(fs_info,
2504 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2505 slot, btrfs_disk_key_objectid(&disk_key),
2506 btrfs_disk_key_type(&disk_key),
2507 btrfs_disk_key_offset(&disk_key),
2508 new_key->objectid, new_key->type,
2509 new_key->offset);
2510 btrfs_print_leaf(eb);
2511 BUG();
2512 }
2513 }
2514
2515 btrfs_cpu_key_to_disk(&disk_key, new_key);
2516 btrfs_set_item_key(eb, &disk_key, slot);
2517 btrfs_mark_buffer_dirty(eb);
2518 if (slot == 0)
2519 fixup_low_keys(path, &disk_key, 1);
2520 }
2521
2522 /*
2523 * Check key order of two sibling extent buffers.
2524 *
2525 * Return true if something is wrong.
2526 * Return false if everything is fine.
2527 *
2528 * Tree-checker only works inside one tree block, thus the following
2529 * corruption can not be detected by tree-checker:
2530 *
2531 * Leaf @left | Leaf @right
2532 * --------------------------------------------------------------
2533 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2534 *
2535 * Key f6 in leaf @left itself is valid, but not valid when the next
2536 * key in leaf @right is 7.
2537 * This can only be checked at tree block merge time.
2538 * And since tree checker has ensured all key order in each tree block
2539 * is correct, we only need to bother the last key of @left and the first
2540 * key of @right.
2541 */
check_sibling_keys(struct extent_buffer * left,struct extent_buffer * right)2542 static bool check_sibling_keys(struct extent_buffer *left,
2543 struct extent_buffer *right)
2544 {
2545 struct btrfs_key left_last;
2546 struct btrfs_key right_first;
2547 int level = btrfs_header_level(left);
2548 int nr_left = btrfs_header_nritems(left);
2549 int nr_right = btrfs_header_nritems(right);
2550
2551 /* No key to check in one of the tree blocks */
2552 if (!nr_left || !nr_right)
2553 return false;
2554
2555 if (level) {
2556 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2557 btrfs_node_key_to_cpu(right, &right_first, 0);
2558 } else {
2559 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2560 btrfs_item_key_to_cpu(right, &right_first, 0);
2561 }
2562
2563 if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
2564 btrfs_crit(left->fs_info,
2565 "bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2566 left_last.objectid, left_last.type,
2567 left_last.offset, right_first.objectid,
2568 right_first.type, right_first.offset);
2569 return true;
2570 }
2571 return false;
2572 }
2573
2574 /*
2575 * try to push data from one node into the next node left in the
2576 * tree.
2577 *
2578 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2579 * error, and > 0 if there was no room in the left hand block.
2580 */
push_node_left(struct btrfs_trans_handle * trans,struct extent_buffer * dst,struct extent_buffer * src,int empty)2581 static int push_node_left(struct btrfs_trans_handle *trans,
2582 struct extent_buffer *dst,
2583 struct extent_buffer *src, int empty)
2584 {
2585 struct btrfs_fs_info *fs_info = trans->fs_info;
2586 int push_items = 0;
2587 int src_nritems;
2588 int dst_nritems;
2589 int ret = 0;
2590
2591 src_nritems = btrfs_header_nritems(src);
2592 dst_nritems = btrfs_header_nritems(dst);
2593 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2594 WARN_ON(btrfs_header_generation(src) != trans->transid);
2595 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2596
2597 if (!empty && src_nritems <= 8)
2598 return 1;
2599
2600 if (push_items <= 0)
2601 return 1;
2602
2603 if (empty) {
2604 push_items = min(src_nritems, push_items);
2605 if (push_items < src_nritems) {
2606 /* leave at least 8 pointers in the node if
2607 * we aren't going to empty it
2608 */
2609 if (src_nritems - push_items < 8) {
2610 if (push_items <= 8)
2611 return 1;
2612 push_items -= 8;
2613 }
2614 }
2615 } else
2616 push_items = min(src_nritems - 8, push_items);
2617
2618 /* dst is the left eb, src is the middle eb */
2619 if (check_sibling_keys(dst, src)) {
2620 ret = -EUCLEAN;
2621 btrfs_abort_transaction(trans, ret);
2622 return ret;
2623 }
2624 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2625 if (ret) {
2626 btrfs_abort_transaction(trans, ret);
2627 return ret;
2628 }
2629 copy_extent_buffer(dst, src,
2630 btrfs_node_key_ptr_offset(dst_nritems),
2631 btrfs_node_key_ptr_offset(0),
2632 push_items * sizeof(struct btrfs_key_ptr));
2633
2634 if (push_items < src_nritems) {
2635 /*
2636 * Don't call btrfs_tree_mod_log_insert_move() here, key removal
2637 * was already fully logged by btrfs_tree_mod_log_eb_copy() above.
2638 */
2639 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
2640 btrfs_node_key_ptr_offset(push_items),
2641 (src_nritems - push_items) *
2642 sizeof(struct btrfs_key_ptr));
2643 }
2644 btrfs_set_header_nritems(src, src_nritems - push_items);
2645 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2646 btrfs_mark_buffer_dirty(src);
2647 btrfs_mark_buffer_dirty(dst);
2648
2649 return ret;
2650 }
2651
2652 /*
2653 * try to push data from one node into the next node right in the
2654 * tree.
2655 *
2656 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2657 * error, and > 0 if there was no room in the right hand block.
2658 *
2659 * this will only push up to 1/2 the contents of the left node over
2660 */
balance_node_right(struct btrfs_trans_handle * trans,struct extent_buffer * dst,struct extent_buffer * src)2661 static int balance_node_right(struct btrfs_trans_handle *trans,
2662 struct extent_buffer *dst,
2663 struct extent_buffer *src)
2664 {
2665 struct btrfs_fs_info *fs_info = trans->fs_info;
2666 int push_items = 0;
2667 int max_push;
2668 int src_nritems;
2669 int dst_nritems;
2670 int ret = 0;
2671
2672 WARN_ON(btrfs_header_generation(src) != trans->transid);
2673 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2674
2675 src_nritems = btrfs_header_nritems(src);
2676 dst_nritems = btrfs_header_nritems(dst);
2677 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2678 if (push_items <= 0)
2679 return 1;
2680
2681 if (src_nritems < 4)
2682 return 1;
2683
2684 max_push = src_nritems / 2 + 1;
2685 /* don't try to empty the node */
2686 if (max_push >= src_nritems)
2687 return 1;
2688
2689 if (max_push < push_items)
2690 push_items = max_push;
2691
2692 /* dst is the right eb, src is the middle eb */
2693 if (check_sibling_keys(src, dst)) {
2694 ret = -EUCLEAN;
2695 btrfs_abort_transaction(trans, ret);
2696 return ret;
2697 }
2698 ret = btrfs_tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
2699 BUG_ON(ret < 0);
2700 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2701 btrfs_node_key_ptr_offset(0),
2702 (dst_nritems) *
2703 sizeof(struct btrfs_key_ptr));
2704
2705 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2706 push_items);
2707 if (ret) {
2708 btrfs_abort_transaction(trans, ret);
2709 return ret;
2710 }
2711 copy_extent_buffer(dst, src,
2712 btrfs_node_key_ptr_offset(0),
2713 btrfs_node_key_ptr_offset(src_nritems - push_items),
2714 push_items * sizeof(struct btrfs_key_ptr));
2715
2716 btrfs_set_header_nritems(src, src_nritems - push_items);
2717 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2718
2719 btrfs_mark_buffer_dirty(src);
2720 btrfs_mark_buffer_dirty(dst);
2721
2722 return ret;
2723 }
2724
2725 /*
2726 * helper function to insert a new root level in the tree.
2727 * A new node is allocated, and a single item is inserted to
2728 * point to the existing root
2729 *
2730 * returns zero on success or < 0 on failure.
2731 */
insert_new_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int level)2732 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2733 struct btrfs_root *root,
2734 struct btrfs_path *path, int level)
2735 {
2736 struct btrfs_fs_info *fs_info = root->fs_info;
2737 u64 lower_gen;
2738 struct extent_buffer *lower;
2739 struct extent_buffer *c;
2740 struct extent_buffer *old;
2741 struct btrfs_disk_key lower_key;
2742 int ret;
2743
2744 BUG_ON(path->nodes[level]);
2745 BUG_ON(path->nodes[level-1] != root->node);
2746
2747 lower = path->nodes[level-1];
2748 if (level == 1)
2749 btrfs_item_key(lower, &lower_key, 0);
2750 else
2751 btrfs_node_key(lower, &lower_key, 0);
2752
2753 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2754 &lower_key, level, root->node->start, 0,
2755 BTRFS_NESTING_NEW_ROOT);
2756 if (IS_ERR(c))
2757 return PTR_ERR(c);
2758
2759 root_add_used(root, fs_info->nodesize);
2760
2761 btrfs_set_header_nritems(c, 1);
2762 btrfs_set_node_key(c, &lower_key, 0);
2763 btrfs_set_node_blockptr(c, 0, lower->start);
2764 lower_gen = btrfs_header_generation(lower);
2765 WARN_ON(lower_gen != trans->transid);
2766
2767 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2768
2769 btrfs_mark_buffer_dirty(c);
2770
2771 old = root->node;
2772 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2773 BUG_ON(ret < 0);
2774 rcu_assign_pointer(root->node, c);
2775
2776 /* the super has an extra ref to root->node */
2777 free_extent_buffer(old);
2778
2779 add_root_to_dirty_list(root);
2780 atomic_inc(&c->refs);
2781 path->nodes[level] = c;
2782 path->locks[level] = BTRFS_WRITE_LOCK;
2783 path->slots[level] = 0;
2784 return 0;
2785 }
2786
2787 /*
2788 * worker function to insert a single pointer in a node.
2789 * the node should have enough room for the pointer already
2790 *
2791 * slot and level indicate where you want the key to go, and
2792 * blocknr is the block the key points to.
2793 */
insert_ptr(struct btrfs_trans_handle * trans,struct btrfs_path * path,struct btrfs_disk_key * key,u64 bytenr,int slot,int level)2794 static void insert_ptr(struct btrfs_trans_handle *trans,
2795 struct btrfs_path *path,
2796 struct btrfs_disk_key *key, u64 bytenr,
2797 int slot, int level)
2798 {
2799 struct extent_buffer *lower;
2800 int nritems;
2801 int ret;
2802
2803 BUG_ON(!path->nodes[level]);
2804 btrfs_assert_tree_write_locked(path->nodes[level]);
2805 lower = path->nodes[level];
2806 nritems = btrfs_header_nritems(lower);
2807 BUG_ON(slot > nritems);
2808 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2809 if (slot != nritems) {
2810 if (level) {
2811 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2812 slot, nritems - slot);
2813 BUG_ON(ret < 0);
2814 }
2815 memmove_extent_buffer(lower,
2816 btrfs_node_key_ptr_offset(slot + 1),
2817 btrfs_node_key_ptr_offset(slot),
2818 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2819 }
2820 if (level) {
2821 ret = btrfs_tree_mod_log_insert_key(lower, slot,
2822 BTRFS_MOD_LOG_KEY_ADD, GFP_NOFS);
2823 BUG_ON(ret < 0);
2824 }
2825 btrfs_set_node_key(lower, key, slot);
2826 btrfs_set_node_blockptr(lower, slot, bytenr);
2827 WARN_ON(trans->transid == 0);
2828 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2829 btrfs_set_header_nritems(lower, nritems + 1);
2830 btrfs_mark_buffer_dirty(lower);
2831 }
2832
2833 /*
2834 * split the node at the specified level in path in two.
2835 * The path is corrected to point to the appropriate node after the split
2836 *
2837 * Before splitting this tries to make some room in the node by pushing
2838 * left and right, if either one works, it returns right away.
2839 *
2840 * returns 0 on success and < 0 on failure
2841 */
split_node(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int level)2842 static noinline int split_node(struct btrfs_trans_handle *trans,
2843 struct btrfs_root *root,
2844 struct btrfs_path *path, int level)
2845 {
2846 struct btrfs_fs_info *fs_info = root->fs_info;
2847 struct extent_buffer *c;
2848 struct extent_buffer *split;
2849 struct btrfs_disk_key disk_key;
2850 int mid;
2851 int ret;
2852 u32 c_nritems;
2853
2854 c = path->nodes[level];
2855 WARN_ON(btrfs_header_generation(c) != trans->transid);
2856 if (c == root->node) {
2857 /*
2858 * trying to split the root, lets make a new one
2859 *
2860 * tree mod log: We don't log_removal old root in
2861 * insert_new_root, because that root buffer will be kept as a
2862 * normal node. We are going to log removal of half of the
2863 * elements below with btrfs_tree_mod_log_eb_copy(). We're
2864 * holding a tree lock on the buffer, which is why we cannot
2865 * race with other tree_mod_log users.
2866 */
2867 ret = insert_new_root(trans, root, path, level + 1);
2868 if (ret)
2869 return ret;
2870 } else {
2871 ret = push_nodes_for_insert(trans, root, path, level);
2872 c = path->nodes[level];
2873 if (!ret && btrfs_header_nritems(c) <
2874 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
2875 return 0;
2876 if (ret < 0)
2877 return ret;
2878 }
2879
2880 c_nritems = btrfs_header_nritems(c);
2881 mid = (c_nritems + 1) / 2;
2882 btrfs_node_key(c, &disk_key, mid);
2883
2884 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2885 &disk_key, level, c->start, 0,
2886 BTRFS_NESTING_SPLIT);
2887 if (IS_ERR(split))
2888 return PTR_ERR(split);
2889
2890 root_add_used(root, fs_info->nodesize);
2891 ASSERT(btrfs_header_level(c) == level);
2892
2893 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
2894 if (ret) {
2895 btrfs_tree_unlock(split);
2896 free_extent_buffer(split);
2897 btrfs_abort_transaction(trans, ret);
2898 return ret;
2899 }
2900 copy_extent_buffer(split, c,
2901 btrfs_node_key_ptr_offset(0),
2902 btrfs_node_key_ptr_offset(mid),
2903 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2904 btrfs_set_header_nritems(split, c_nritems - mid);
2905 btrfs_set_header_nritems(c, mid);
2906
2907 btrfs_mark_buffer_dirty(c);
2908 btrfs_mark_buffer_dirty(split);
2909
2910 insert_ptr(trans, path, &disk_key, split->start,
2911 path->slots[level + 1] + 1, level + 1);
2912
2913 if (path->slots[level] >= mid) {
2914 path->slots[level] -= mid;
2915 btrfs_tree_unlock(c);
2916 free_extent_buffer(c);
2917 path->nodes[level] = split;
2918 path->slots[level + 1] += 1;
2919 } else {
2920 btrfs_tree_unlock(split);
2921 free_extent_buffer(split);
2922 }
2923 return 0;
2924 }
2925
2926 /*
2927 * how many bytes are required to store the items in a leaf. start
2928 * and nr indicate which items in the leaf to check. This totals up the
2929 * space used both by the item structs and the item data
2930 */
leaf_space_used(struct extent_buffer * l,int start,int nr)2931 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2932 {
2933 int data_len;
2934 int nritems = btrfs_header_nritems(l);
2935 int end = min(nritems, start + nr) - 1;
2936
2937 if (!nr)
2938 return 0;
2939 data_len = btrfs_item_offset(l, start) + btrfs_item_size(l, start);
2940 data_len = data_len - btrfs_item_offset(l, end);
2941 data_len += sizeof(struct btrfs_item) * nr;
2942 WARN_ON(data_len < 0);
2943 return data_len;
2944 }
2945
2946 /*
2947 * The space between the end of the leaf items and
2948 * the start of the leaf data. IOW, how much room
2949 * the leaf has left for both items and data
2950 */
btrfs_leaf_free_space(struct extent_buffer * leaf)2951 noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
2952 {
2953 struct btrfs_fs_info *fs_info = leaf->fs_info;
2954 int nritems = btrfs_header_nritems(leaf);
2955 int ret;
2956
2957 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
2958 if (ret < 0) {
2959 btrfs_crit(fs_info,
2960 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
2961 ret,
2962 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
2963 leaf_space_used(leaf, 0, nritems), nritems);
2964 }
2965 return ret;
2966 }
2967
2968 /*
2969 * min slot controls the lowest index we're willing to push to the
2970 * right. We'll push up to and including min_slot, but no lower
2971 */
__push_leaf_right(struct btrfs_path * path,int data_size,int empty,struct extent_buffer * right,int free_space,u32 left_nritems,u32 min_slot)2972 static noinline int __push_leaf_right(struct btrfs_path *path,
2973 int data_size, int empty,
2974 struct extent_buffer *right,
2975 int free_space, u32 left_nritems,
2976 u32 min_slot)
2977 {
2978 struct btrfs_fs_info *fs_info = right->fs_info;
2979 struct extent_buffer *left = path->nodes[0];
2980 struct extent_buffer *upper = path->nodes[1];
2981 struct btrfs_map_token token;
2982 struct btrfs_disk_key disk_key;
2983 int slot;
2984 u32 i;
2985 int push_space = 0;
2986 int push_items = 0;
2987 u32 nr;
2988 u32 right_nritems;
2989 u32 data_end;
2990 u32 this_item_size;
2991
2992 if (empty)
2993 nr = 0;
2994 else
2995 nr = max_t(u32, 1, min_slot);
2996
2997 if (path->slots[0] >= left_nritems)
2998 push_space += data_size;
2999
3000 slot = path->slots[1];
3001 i = left_nritems - 1;
3002 while (i >= nr) {
3003 if (!empty && push_items > 0) {
3004 if (path->slots[0] > i)
3005 break;
3006 if (path->slots[0] == i) {
3007 int space = btrfs_leaf_free_space(left);
3008
3009 if (space + push_space * 2 > free_space)
3010 break;
3011 }
3012 }
3013
3014 if (path->slots[0] == i)
3015 push_space += data_size;
3016
3017 this_item_size = btrfs_item_size(left, i);
3018 if (this_item_size + sizeof(struct btrfs_item) +
3019 push_space > free_space)
3020 break;
3021
3022 push_items++;
3023 push_space += this_item_size + sizeof(struct btrfs_item);
3024 if (i == 0)
3025 break;
3026 i--;
3027 }
3028
3029 if (push_items == 0)
3030 goto out_unlock;
3031
3032 WARN_ON(!empty && push_items == left_nritems);
3033
3034 /* push left to right */
3035 right_nritems = btrfs_header_nritems(right);
3036
3037 push_space = btrfs_item_data_end(left, left_nritems - push_items);
3038 push_space -= leaf_data_end(left);
3039
3040 /* make room in the right data area */
3041 data_end = leaf_data_end(right);
3042 memmove_extent_buffer(right,
3043 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3044 BTRFS_LEAF_DATA_OFFSET + data_end,
3045 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3046
3047 /* copy from the left data area */
3048 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3049 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3050 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3051 push_space);
3052
3053 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3054 btrfs_item_nr_offset(0),
3055 right_nritems * sizeof(struct btrfs_item));
3056
3057 /* copy the items from left to right */
3058 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3059 btrfs_item_nr_offset(left_nritems - push_items),
3060 push_items * sizeof(struct btrfs_item));
3061
3062 /* update the item pointers */
3063 btrfs_init_map_token(&token, right);
3064 right_nritems += push_items;
3065 btrfs_set_header_nritems(right, right_nritems);
3066 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3067 for (i = 0; i < right_nritems; i++) {
3068 push_space -= btrfs_token_item_size(&token, i);
3069 btrfs_set_token_item_offset(&token, i, push_space);
3070 }
3071
3072 left_nritems -= push_items;
3073 btrfs_set_header_nritems(left, left_nritems);
3074
3075 if (left_nritems)
3076 btrfs_mark_buffer_dirty(left);
3077 else
3078 btrfs_clean_tree_block(left);
3079
3080 btrfs_mark_buffer_dirty(right);
3081
3082 btrfs_item_key(right, &disk_key, 0);
3083 btrfs_set_node_key(upper, &disk_key, slot + 1);
3084 btrfs_mark_buffer_dirty(upper);
3085
3086 /* then fixup the leaf pointer in the path */
3087 if (path->slots[0] >= left_nritems) {
3088 path->slots[0] -= left_nritems;
3089 if (btrfs_header_nritems(path->nodes[0]) == 0)
3090 btrfs_clean_tree_block(path->nodes[0]);
3091 btrfs_tree_unlock(path->nodes[0]);
3092 free_extent_buffer(path->nodes[0]);
3093 path->nodes[0] = right;
3094 path->slots[1] += 1;
3095 } else {
3096 btrfs_tree_unlock(right);
3097 free_extent_buffer(right);
3098 }
3099 return 0;
3100
3101 out_unlock:
3102 btrfs_tree_unlock(right);
3103 free_extent_buffer(right);
3104 return 1;
3105 }
3106
3107 /*
3108 * push some data in the path leaf to the right, trying to free up at
3109 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3110 *
3111 * returns 1 if the push failed because the other node didn't have enough
3112 * room, 0 if everything worked out and < 0 if there were major errors.
3113 *
3114 * this will push starting from min_slot to the end of the leaf. It won't
3115 * push any slot lower than min_slot
3116 */
push_leaf_right(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int min_data_size,int data_size,int empty,u32 min_slot)3117 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3118 *root, struct btrfs_path *path,
3119 int min_data_size, int data_size,
3120 int empty, u32 min_slot)
3121 {
3122 struct extent_buffer *left = path->nodes[0];
3123 struct extent_buffer *right;
3124 struct extent_buffer *upper;
3125 int slot;
3126 int free_space;
3127 u32 left_nritems;
3128 int ret;
3129
3130 if (!path->nodes[1])
3131 return 1;
3132
3133 slot = path->slots[1];
3134 upper = path->nodes[1];
3135 if (slot >= btrfs_header_nritems(upper) - 1)
3136 return 1;
3137
3138 btrfs_assert_tree_write_locked(path->nodes[1]);
3139
3140 right = btrfs_read_node_slot(upper, slot + 1);
3141 /*
3142 * slot + 1 is not valid or we fail to read the right node,
3143 * no big deal, just return.
3144 */
3145 if (IS_ERR(right))
3146 return 1;
3147
3148 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
3149
3150 free_space = btrfs_leaf_free_space(right);
3151 if (free_space < data_size)
3152 goto out_unlock;
3153
3154 ret = btrfs_cow_block(trans, root, right, upper,
3155 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
3156 if (ret)
3157 goto out_unlock;
3158
3159 left_nritems = btrfs_header_nritems(left);
3160 if (left_nritems == 0)
3161 goto out_unlock;
3162
3163 if (check_sibling_keys(left, right)) {
3164 ret = -EUCLEAN;
3165 btrfs_abort_transaction(trans, ret);
3166 btrfs_tree_unlock(right);
3167 free_extent_buffer(right);
3168 return ret;
3169 }
3170 if (path->slots[0] == left_nritems && !empty) {
3171 /* Key greater than all keys in the leaf, right neighbor has
3172 * enough room for it and we're not emptying our leaf to delete
3173 * it, therefore use right neighbor to insert the new item and
3174 * no need to touch/dirty our left leaf. */
3175 btrfs_tree_unlock(left);
3176 free_extent_buffer(left);
3177 path->nodes[0] = right;
3178 path->slots[0] = 0;
3179 path->slots[1]++;
3180 return 0;
3181 }
3182
3183 return __push_leaf_right(path, min_data_size, empty,
3184 right, free_space, left_nritems, min_slot);
3185 out_unlock:
3186 btrfs_tree_unlock(right);
3187 free_extent_buffer(right);
3188 return 1;
3189 }
3190
3191 /*
3192 * push some data in the path leaf to the left, trying to free up at
3193 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3194 *
3195 * max_slot can put a limit on how far into the leaf we'll push items. The
3196 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3197 * items
3198 */
__push_leaf_left(struct btrfs_path * path,int data_size,int empty,struct extent_buffer * left,int free_space,u32 right_nritems,u32 max_slot)3199 static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
3200 int empty, struct extent_buffer *left,
3201 int free_space, u32 right_nritems,
3202 u32 max_slot)
3203 {
3204 struct btrfs_fs_info *fs_info = left->fs_info;
3205 struct btrfs_disk_key disk_key;
3206 struct extent_buffer *right = path->nodes[0];
3207 int i;
3208 int push_space = 0;
3209 int push_items = 0;
3210 u32 old_left_nritems;
3211 u32 nr;
3212 int ret = 0;
3213 u32 this_item_size;
3214 u32 old_left_item_size;
3215 struct btrfs_map_token token;
3216
3217 if (empty)
3218 nr = min(right_nritems, max_slot);
3219 else
3220 nr = min(right_nritems - 1, max_slot);
3221
3222 for (i = 0; i < nr; i++) {
3223 if (!empty && push_items > 0) {
3224 if (path->slots[0] < i)
3225 break;
3226 if (path->slots[0] == i) {
3227 int space = btrfs_leaf_free_space(right);
3228
3229 if (space + push_space * 2 > free_space)
3230 break;
3231 }
3232 }
3233
3234 if (path->slots[0] == i)
3235 push_space += data_size;
3236
3237 this_item_size = btrfs_item_size(right, i);
3238 if (this_item_size + sizeof(struct btrfs_item) + push_space >
3239 free_space)
3240 break;
3241
3242 push_items++;
3243 push_space += this_item_size + sizeof(struct btrfs_item);
3244 }
3245
3246 if (push_items == 0) {
3247 ret = 1;
3248 goto out;
3249 }
3250 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3251
3252 /* push data from right to left */
3253 copy_extent_buffer(left, right,
3254 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3255 btrfs_item_nr_offset(0),
3256 push_items * sizeof(struct btrfs_item));
3257
3258 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3259 btrfs_item_offset(right, push_items - 1);
3260
3261 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3262 leaf_data_end(left) - push_space,
3263 BTRFS_LEAF_DATA_OFFSET +
3264 btrfs_item_offset(right, push_items - 1),
3265 push_space);
3266 old_left_nritems = btrfs_header_nritems(left);
3267 BUG_ON(old_left_nritems <= 0);
3268
3269 btrfs_init_map_token(&token, left);
3270 old_left_item_size = btrfs_item_offset(left, old_left_nritems - 1);
3271 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3272 u32 ioff;
3273
3274 ioff = btrfs_token_item_offset(&token, i);
3275 btrfs_set_token_item_offset(&token, i,
3276 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
3277 }
3278 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3279
3280 /* fixup right node */
3281 if (push_items > right_nritems)
3282 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3283 right_nritems);
3284
3285 if (push_items < right_nritems) {
3286 push_space = btrfs_item_offset(right, push_items - 1) -
3287 leaf_data_end(right);
3288 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3289 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3290 BTRFS_LEAF_DATA_OFFSET +
3291 leaf_data_end(right), push_space);
3292
3293 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3294 btrfs_item_nr_offset(push_items),
3295 (btrfs_header_nritems(right) - push_items) *
3296 sizeof(struct btrfs_item));
3297 }
3298
3299 btrfs_init_map_token(&token, right);
3300 right_nritems -= push_items;
3301 btrfs_set_header_nritems(right, right_nritems);
3302 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3303 for (i = 0; i < right_nritems; i++) {
3304 push_space = push_space - btrfs_token_item_size(&token, i);
3305 btrfs_set_token_item_offset(&token, i, push_space);
3306 }
3307
3308 btrfs_mark_buffer_dirty(left);
3309 if (right_nritems)
3310 btrfs_mark_buffer_dirty(right);
3311 else
3312 btrfs_clean_tree_block(right);
3313
3314 btrfs_item_key(right, &disk_key, 0);
3315 fixup_low_keys(path, &disk_key, 1);
3316
3317 /* then fixup the leaf pointer in the path */
3318 if (path->slots[0] < push_items) {
3319 path->slots[0] += old_left_nritems;
3320 btrfs_tree_unlock(path->nodes[0]);
3321 free_extent_buffer(path->nodes[0]);
3322 path->nodes[0] = left;
3323 path->slots[1] -= 1;
3324 } else {
3325 btrfs_tree_unlock(left);
3326 free_extent_buffer(left);
3327 path->slots[0] -= push_items;
3328 }
3329 BUG_ON(path->slots[0] < 0);
3330 return ret;
3331 out:
3332 btrfs_tree_unlock(left);
3333 free_extent_buffer(left);
3334 return ret;
3335 }
3336
3337 /*
3338 * push some data in the path leaf to the left, trying to free up at
3339 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3340 *
3341 * max_slot can put a limit on how far into the leaf we'll push items. The
3342 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3343 * items
3344 */
push_leaf_left(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int min_data_size,int data_size,int empty,u32 max_slot)3345 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3346 *root, struct btrfs_path *path, int min_data_size,
3347 int data_size, int empty, u32 max_slot)
3348 {
3349 struct extent_buffer *right = path->nodes[0];
3350 struct extent_buffer *left;
3351 int slot;
3352 int free_space;
3353 u32 right_nritems;
3354 int ret = 0;
3355
3356 slot = path->slots[1];
3357 if (slot == 0)
3358 return 1;
3359 if (!path->nodes[1])
3360 return 1;
3361
3362 right_nritems = btrfs_header_nritems(right);
3363 if (right_nritems == 0)
3364 return 1;
3365
3366 btrfs_assert_tree_write_locked(path->nodes[1]);
3367
3368 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3369 /*
3370 * slot - 1 is not valid or we fail to read the left node,
3371 * no big deal, just return.
3372 */
3373 if (IS_ERR(left))
3374 return 1;
3375
3376 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
3377
3378 free_space = btrfs_leaf_free_space(left);
3379 if (free_space < data_size) {
3380 ret = 1;
3381 goto out;
3382 }
3383
3384 ret = btrfs_cow_block(trans, root, left,
3385 path->nodes[1], slot - 1, &left,
3386 BTRFS_NESTING_LEFT_COW);
3387 if (ret) {
3388 /* we hit -ENOSPC, but it isn't fatal here */
3389 if (ret == -ENOSPC)
3390 ret = 1;
3391 goto out;
3392 }
3393
3394 if (check_sibling_keys(left, right)) {
3395 ret = -EUCLEAN;
3396 btrfs_abort_transaction(trans, ret);
3397 goto out;
3398 }
3399 return __push_leaf_left(path, min_data_size,
3400 empty, left, free_space, right_nritems,
3401 max_slot);
3402 out:
3403 btrfs_tree_unlock(left);
3404 free_extent_buffer(left);
3405 return ret;
3406 }
3407
3408 /*
3409 * split the path's leaf in two, making sure there is at least data_size
3410 * available for the resulting leaf level of the path.
3411 */
copy_for_split(struct btrfs_trans_handle * trans,struct btrfs_path * path,struct extent_buffer * l,struct extent_buffer * right,int slot,int mid,int nritems)3412 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3413 struct btrfs_path *path,
3414 struct extent_buffer *l,
3415 struct extent_buffer *right,
3416 int slot, int mid, int nritems)
3417 {
3418 struct btrfs_fs_info *fs_info = trans->fs_info;
3419 int data_copy_size;
3420 int rt_data_off;
3421 int i;
3422 struct btrfs_disk_key disk_key;
3423 struct btrfs_map_token token;
3424
3425 nritems = nritems - mid;
3426 btrfs_set_header_nritems(right, nritems);
3427 data_copy_size = btrfs_item_data_end(l, mid) - leaf_data_end(l);
3428
3429 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3430 btrfs_item_nr_offset(mid),
3431 nritems * sizeof(struct btrfs_item));
3432
3433 copy_extent_buffer(right, l,
3434 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
3435 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
3436 leaf_data_end(l), data_copy_size);
3437
3438 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_data_end(l, mid);
3439
3440 btrfs_init_map_token(&token, right);
3441 for (i = 0; i < nritems; i++) {
3442 u32 ioff;
3443
3444 ioff = btrfs_token_item_offset(&token, i);
3445 btrfs_set_token_item_offset(&token, i, ioff + rt_data_off);
3446 }
3447
3448 btrfs_set_header_nritems(l, mid);
3449 btrfs_item_key(right, &disk_key, 0);
3450 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3451
3452 btrfs_mark_buffer_dirty(right);
3453 btrfs_mark_buffer_dirty(l);
3454 BUG_ON(path->slots[0] != slot);
3455
3456 if (mid <= slot) {
3457 btrfs_tree_unlock(path->nodes[0]);
3458 free_extent_buffer(path->nodes[0]);
3459 path->nodes[0] = right;
3460 path->slots[0] -= mid;
3461 path->slots[1] += 1;
3462 } else {
3463 btrfs_tree_unlock(right);
3464 free_extent_buffer(right);
3465 }
3466
3467 BUG_ON(path->slots[0] < 0);
3468 }
3469
3470 /*
3471 * double splits happen when we need to insert a big item in the middle
3472 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3473 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3474 * A B C
3475 *
3476 * We avoid this by trying to push the items on either side of our target
3477 * into the adjacent leaves. If all goes well we can avoid the double split
3478 * completely.
3479 */
push_for_double_split(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int data_size)3480 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3481 struct btrfs_root *root,
3482 struct btrfs_path *path,
3483 int data_size)
3484 {
3485 int ret;
3486 int progress = 0;
3487 int slot;
3488 u32 nritems;
3489 int space_needed = data_size;
3490
3491 slot = path->slots[0];
3492 if (slot < btrfs_header_nritems(path->nodes[0]))
3493 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3494
3495 /*
3496 * try to push all the items after our slot into the
3497 * right leaf
3498 */
3499 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3500 if (ret < 0)
3501 return ret;
3502
3503 if (ret == 0)
3504 progress++;
3505
3506 nritems = btrfs_header_nritems(path->nodes[0]);
3507 /*
3508 * our goal is to get our slot at the start or end of a leaf. If
3509 * we've done so we're done
3510 */
3511 if (path->slots[0] == 0 || path->slots[0] == nritems)
3512 return 0;
3513
3514 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3515 return 0;
3516
3517 /* try to push all the items before our slot into the next leaf */
3518 slot = path->slots[0];
3519 space_needed = data_size;
3520 if (slot > 0)
3521 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3522 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3523 if (ret < 0)
3524 return ret;
3525
3526 if (ret == 0)
3527 progress++;
3528
3529 if (progress)
3530 return 0;
3531 return 1;
3532 }
3533
3534 /*
3535 * split the path's leaf in two, making sure there is at least data_size
3536 * available for the resulting leaf level of the path.
3537 *
3538 * returns 0 if all went well and < 0 on failure.
3539 */
split_leaf(struct btrfs_trans_handle * trans,struct btrfs_root * root,const struct btrfs_key * ins_key,struct btrfs_path * path,int data_size,int extend)3540 static noinline int split_leaf(struct btrfs_trans_handle *trans,
3541 struct btrfs_root *root,
3542 const struct btrfs_key *ins_key,
3543 struct btrfs_path *path, int data_size,
3544 int extend)
3545 {
3546 struct btrfs_disk_key disk_key;
3547 struct extent_buffer *l;
3548 u32 nritems;
3549 int mid;
3550 int slot;
3551 struct extent_buffer *right;
3552 struct btrfs_fs_info *fs_info = root->fs_info;
3553 int ret = 0;
3554 int wret;
3555 int split;
3556 int num_doubles = 0;
3557 int tried_avoid_double = 0;
3558
3559 l = path->nodes[0];
3560 slot = path->slots[0];
3561 if (extend && data_size + btrfs_item_size(l, slot) +
3562 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3563 return -EOVERFLOW;
3564
3565 /* first try to make some room by pushing left and right */
3566 if (data_size && path->nodes[1]) {
3567 int space_needed = data_size;
3568
3569 if (slot < btrfs_header_nritems(l))
3570 space_needed -= btrfs_leaf_free_space(l);
3571
3572 wret = push_leaf_right(trans, root, path, space_needed,
3573 space_needed, 0, 0);
3574 if (wret < 0)
3575 return wret;
3576 if (wret) {
3577 space_needed = data_size;
3578 if (slot > 0)
3579 space_needed -= btrfs_leaf_free_space(l);
3580 wret = push_leaf_left(trans, root, path, space_needed,
3581 space_needed, 0, (u32)-1);
3582 if (wret < 0)
3583 return wret;
3584 }
3585 l = path->nodes[0];
3586
3587 /* did the pushes work? */
3588 if (btrfs_leaf_free_space(l) >= data_size)
3589 return 0;
3590 }
3591
3592 if (!path->nodes[1]) {
3593 ret = insert_new_root(trans, root, path, 1);
3594 if (ret)
3595 return ret;
3596 }
3597 again:
3598 split = 1;
3599 l = path->nodes[0];
3600 slot = path->slots[0];
3601 nritems = btrfs_header_nritems(l);
3602 mid = (nritems + 1) / 2;
3603
3604 if (mid <= slot) {
3605 if (nritems == 1 ||
3606 leaf_space_used(l, mid, nritems - mid) + data_size >
3607 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3608 if (slot >= nritems) {
3609 split = 0;
3610 } else {
3611 mid = slot;
3612 if (mid != nritems &&
3613 leaf_space_used(l, mid, nritems - mid) +
3614 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3615 if (data_size && !tried_avoid_double)
3616 goto push_for_double;
3617 split = 2;
3618 }
3619 }
3620 }
3621 } else {
3622 if (leaf_space_used(l, 0, mid) + data_size >
3623 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3624 if (!extend && data_size && slot == 0) {
3625 split = 0;
3626 } else if ((extend || !data_size) && slot == 0) {
3627 mid = 1;
3628 } else {
3629 mid = slot;
3630 if (mid != nritems &&
3631 leaf_space_used(l, mid, nritems - mid) +
3632 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3633 if (data_size && !tried_avoid_double)
3634 goto push_for_double;
3635 split = 2;
3636 }
3637 }
3638 }
3639 }
3640
3641 if (split == 0)
3642 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3643 else
3644 btrfs_item_key(l, &disk_key, mid);
3645
3646 /*
3647 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3648 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3649 * subclasses, which is 8 at the time of this patch, and we've maxed it
3650 * out. In the future we could add a
3651 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3652 * use BTRFS_NESTING_NEW_ROOT.
3653 */
3654 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3655 &disk_key, 0, l->start, 0,
3656 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3657 BTRFS_NESTING_SPLIT);
3658 if (IS_ERR(right))
3659 return PTR_ERR(right);
3660
3661 root_add_used(root, fs_info->nodesize);
3662
3663 if (split == 0) {
3664 if (mid <= slot) {
3665 btrfs_set_header_nritems(right, 0);
3666 insert_ptr(trans, path, &disk_key,
3667 right->start, path->slots[1] + 1, 1);
3668 btrfs_tree_unlock(path->nodes[0]);
3669 free_extent_buffer(path->nodes[0]);
3670 path->nodes[0] = right;
3671 path->slots[0] = 0;
3672 path->slots[1] += 1;
3673 } else {
3674 btrfs_set_header_nritems(right, 0);
3675 insert_ptr(trans, path, &disk_key,
3676 right->start, path->slots[1], 1);
3677 btrfs_tree_unlock(path->nodes[0]);
3678 free_extent_buffer(path->nodes[0]);
3679 path->nodes[0] = right;
3680 path->slots[0] = 0;
3681 if (path->slots[1] == 0)
3682 fixup_low_keys(path, &disk_key, 1);
3683 }
3684 /*
3685 * We create a new leaf 'right' for the required ins_len and
3686 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3687 * the content of ins_len to 'right'.
3688 */
3689 return ret;
3690 }
3691
3692 copy_for_split(trans, path, l, right, slot, mid, nritems);
3693
3694 if (split == 2) {
3695 BUG_ON(num_doubles != 0);
3696 num_doubles++;
3697 goto again;
3698 }
3699
3700 return 0;
3701
3702 push_for_double:
3703 push_for_double_split(trans, root, path, data_size);
3704 tried_avoid_double = 1;
3705 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3706 return 0;
3707 goto again;
3708 }
3709
setup_leaf_for_split(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int ins_len)3710 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3711 struct btrfs_root *root,
3712 struct btrfs_path *path, int ins_len)
3713 {
3714 struct btrfs_key key;
3715 struct extent_buffer *leaf;
3716 struct btrfs_file_extent_item *fi;
3717 u64 extent_len = 0;
3718 u32 item_size;
3719 int ret;
3720
3721 leaf = path->nodes[0];
3722 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3723
3724 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3725 key.type != BTRFS_EXTENT_CSUM_KEY);
3726
3727 if (btrfs_leaf_free_space(leaf) >= ins_len)
3728 return 0;
3729
3730 item_size = btrfs_item_size(leaf, path->slots[0]);
3731 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3732 fi = btrfs_item_ptr(leaf, path->slots[0],
3733 struct btrfs_file_extent_item);
3734 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3735 }
3736 btrfs_release_path(path);
3737
3738 path->keep_locks = 1;
3739 path->search_for_split = 1;
3740 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3741 path->search_for_split = 0;
3742 if (ret > 0)
3743 ret = -EAGAIN;
3744 if (ret < 0)
3745 goto err;
3746
3747 ret = -EAGAIN;
3748 leaf = path->nodes[0];
3749 /* if our item isn't there, return now */
3750 if (item_size != btrfs_item_size(leaf, path->slots[0]))
3751 goto err;
3752
3753 /* the leaf has changed, it now has room. return now */
3754 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3755 goto err;
3756
3757 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3758 fi = btrfs_item_ptr(leaf, path->slots[0],
3759 struct btrfs_file_extent_item);
3760 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3761 goto err;
3762 }
3763
3764 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3765 if (ret)
3766 goto err;
3767
3768 path->keep_locks = 0;
3769 btrfs_unlock_up_safe(path, 1);
3770 return 0;
3771 err:
3772 path->keep_locks = 0;
3773 return ret;
3774 }
3775
split_item(struct btrfs_path * path,const struct btrfs_key * new_key,unsigned long split_offset)3776 static noinline int split_item(struct btrfs_path *path,
3777 const struct btrfs_key *new_key,
3778 unsigned long split_offset)
3779 {
3780 struct extent_buffer *leaf;
3781 int orig_slot, slot;
3782 char *buf;
3783 u32 nritems;
3784 u32 item_size;
3785 u32 orig_offset;
3786 struct btrfs_disk_key disk_key;
3787
3788 leaf = path->nodes[0];
3789 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
3790
3791 orig_slot = path->slots[0];
3792 orig_offset = btrfs_item_offset(leaf, path->slots[0]);
3793 item_size = btrfs_item_size(leaf, path->slots[0]);
3794
3795 buf = kmalloc(item_size, GFP_NOFS);
3796 if (!buf)
3797 return -ENOMEM;
3798
3799 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3800 path->slots[0]), item_size);
3801
3802 slot = path->slots[0] + 1;
3803 nritems = btrfs_header_nritems(leaf);
3804 if (slot != nritems) {
3805 /* shift the items */
3806 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3807 btrfs_item_nr_offset(slot),
3808 (nritems - slot) * sizeof(struct btrfs_item));
3809 }
3810
3811 btrfs_cpu_key_to_disk(&disk_key, new_key);
3812 btrfs_set_item_key(leaf, &disk_key, slot);
3813
3814 btrfs_set_item_offset(leaf, slot, orig_offset);
3815 btrfs_set_item_size(leaf, slot, item_size - split_offset);
3816
3817 btrfs_set_item_offset(leaf, orig_slot,
3818 orig_offset + item_size - split_offset);
3819 btrfs_set_item_size(leaf, orig_slot, split_offset);
3820
3821 btrfs_set_header_nritems(leaf, nritems + 1);
3822
3823 /* write the data for the start of the original item */
3824 write_extent_buffer(leaf, buf,
3825 btrfs_item_ptr_offset(leaf, path->slots[0]),
3826 split_offset);
3827
3828 /* write the data for the new item */
3829 write_extent_buffer(leaf, buf + split_offset,
3830 btrfs_item_ptr_offset(leaf, slot),
3831 item_size - split_offset);
3832 btrfs_mark_buffer_dirty(leaf);
3833
3834 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
3835 kfree(buf);
3836 return 0;
3837 }
3838
3839 /*
3840 * This function splits a single item into two items,
3841 * giving 'new_key' to the new item and splitting the
3842 * old one at split_offset (from the start of the item).
3843 *
3844 * The path may be released by this operation. After
3845 * the split, the path is pointing to the old item. The
3846 * new item is going to be in the same node as the old one.
3847 *
3848 * Note, the item being split must be smaller enough to live alone on
3849 * a tree block with room for one extra struct btrfs_item
3850 *
3851 * This allows us to split the item in place, keeping a lock on the
3852 * leaf the entire time.
3853 */
btrfs_split_item(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,const struct btrfs_key * new_key,unsigned long split_offset)3854 int btrfs_split_item(struct btrfs_trans_handle *trans,
3855 struct btrfs_root *root,
3856 struct btrfs_path *path,
3857 const struct btrfs_key *new_key,
3858 unsigned long split_offset)
3859 {
3860 int ret;
3861 ret = setup_leaf_for_split(trans, root, path,
3862 sizeof(struct btrfs_item));
3863 if (ret)
3864 return ret;
3865
3866 ret = split_item(path, new_key, split_offset);
3867 return ret;
3868 }
3869
3870 /*
3871 * make the item pointed to by the path smaller. new_size indicates
3872 * how small to make it, and from_end tells us if we just chop bytes
3873 * off the end of the item or if we shift the item to chop bytes off
3874 * the front.
3875 */
btrfs_truncate_item(struct btrfs_path * path,u32 new_size,int from_end)3876 void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
3877 {
3878 int slot;
3879 struct extent_buffer *leaf;
3880 u32 nritems;
3881 unsigned int data_end;
3882 unsigned int old_data_start;
3883 unsigned int old_size;
3884 unsigned int size_diff;
3885 int i;
3886 struct btrfs_map_token token;
3887
3888 leaf = path->nodes[0];
3889 slot = path->slots[0];
3890
3891 old_size = btrfs_item_size(leaf, slot);
3892 if (old_size == new_size)
3893 return;
3894
3895 nritems = btrfs_header_nritems(leaf);
3896 data_end = leaf_data_end(leaf);
3897
3898 old_data_start = btrfs_item_offset(leaf, slot);
3899
3900 size_diff = old_size - new_size;
3901
3902 BUG_ON(slot < 0);
3903 BUG_ON(slot >= nritems);
3904
3905 /*
3906 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3907 */
3908 /* first correct the data pointers */
3909 btrfs_init_map_token(&token, leaf);
3910 for (i = slot; i < nritems; i++) {
3911 u32 ioff;
3912
3913 ioff = btrfs_token_item_offset(&token, i);
3914 btrfs_set_token_item_offset(&token, i, ioff + size_diff);
3915 }
3916
3917 /* shift the data */
3918 if (from_end) {
3919 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3920 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3921 data_end, old_data_start + new_size - data_end);
3922 } else {
3923 struct btrfs_disk_key disk_key;
3924 u64 offset;
3925
3926 btrfs_item_key(leaf, &disk_key, slot);
3927
3928 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3929 unsigned long ptr;
3930 struct btrfs_file_extent_item *fi;
3931
3932 fi = btrfs_item_ptr(leaf, slot,
3933 struct btrfs_file_extent_item);
3934 fi = (struct btrfs_file_extent_item *)(
3935 (unsigned long)fi - size_diff);
3936
3937 if (btrfs_file_extent_type(leaf, fi) ==
3938 BTRFS_FILE_EXTENT_INLINE) {
3939 ptr = btrfs_item_ptr_offset(leaf, slot);
3940 memmove_extent_buffer(leaf, ptr,
3941 (unsigned long)fi,
3942 BTRFS_FILE_EXTENT_INLINE_DATA_START);
3943 }
3944 }
3945
3946 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3947 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3948 data_end, old_data_start - data_end);
3949
3950 offset = btrfs_disk_key_offset(&disk_key);
3951 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3952 btrfs_set_item_key(leaf, &disk_key, slot);
3953 if (slot == 0)
3954 fixup_low_keys(path, &disk_key, 1);
3955 }
3956
3957 btrfs_set_item_size(leaf, slot, new_size);
3958 btrfs_mark_buffer_dirty(leaf);
3959
3960 if (btrfs_leaf_free_space(leaf) < 0) {
3961 btrfs_print_leaf(leaf);
3962 BUG();
3963 }
3964 }
3965
3966 /*
3967 * make the item pointed to by the path bigger, data_size is the added size.
3968 */
btrfs_extend_item(struct btrfs_path * path,u32 data_size)3969 void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
3970 {
3971 int slot;
3972 struct extent_buffer *leaf;
3973 u32 nritems;
3974 unsigned int data_end;
3975 unsigned int old_data;
3976 unsigned int old_size;
3977 int i;
3978 struct btrfs_map_token token;
3979
3980 leaf = path->nodes[0];
3981
3982 nritems = btrfs_header_nritems(leaf);
3983 data_end = leaf_data_end(leaf);
3984
3985 if (btrfs_leaf_free_space(leaf) < data_size) {
3986 btrfs_print_leaf(leaf);
3987 BUG();
3988 }
3989 slot = path->slots[0];
3990 old_data = btrfs_item_data_end(leaf, slot);
3991
3992 BUG_ON(slot < 0);
3993 if (slot >= nritems) {
3994 btrfs_print_leaf(leaf);
3995 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
3996 slot, nritems);
3997 BUG();
3998 }
3999
4000 /*
4001 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4002 */
4003 /* first correct the data pointers */
4004 btrfs_init_map_token(&token, leaf);
4005 for (i = slot; i < nritems; i++) {
4006 u32 ioff;
4007
4008 ioff = btrfs_token_item_offset(&token, i);
4009 btrfs_set_token_item_offset(&token, i, ioff - data_size);
4010 }
4011
4012 /* shift the data */
4013 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4014 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4015 data_end, old_data - data_end);
4016
4017 data_end = old_data;
4018 old_size = btrfs_item_size(leaf, slot);
4019 btrfs_set_item_size(leaf, slot, old_size + data_size);
4020 btrfs_mark_buffer_dirty(leaf);
4021
4022 if (btrfs_leaf_free_space(leaf) < 0) {
4023 btrfs_print_leaf(leaf);
4024 BUG();
4025 }
4026 }
4027
4028 /**
4029 * setup_items_for_insert - Helper called before inserting one or more items
4030 * to a leaf. Main purpose is to save stack depth by doing the bulk of the work
4031 * in a function that doesn't call btrfs_search_slot
4032 *
4033 * @root: root we are inserting items to
4034 * @path: points to the leaf/slot where we are going to insert new items
4035 * @batch: information about the batch of items to insert
4036 */
setup_items_for_insert(struct btrfs_root * root,struct btrfs_path * path,const struct btrfs_item_batch * batch)4037 static void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4038 const struct btrfs_item_batch *batch)
4039 {
4040 struct btrfs_fs_info *fs_info = root->fs_info;
4041 int i;
4042 u32 nritems;
4043 unsigned int data_end;
4044 struct btrfs_disk_key disk_key;
4045 struct extent_buffer *leaf;
4046 int slot;
4047 struct btrfs_map_token token;
4048 u32 total_size;
4049
4050 /*
4051 * Before anything else, update keys in the parent and other ancestors
4052 * if needed, then release the write locks on them, so that other tasks
4053 * can use them while we modify the leaf.
4054 */
4055 if (path->slots[0] == 0) {
4056 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[0]);
4057 fixup_low_keys(path, &disk_key, 1);
4058 }
4059 btrfs_unlock_up_safe(path, 1);
4060
4061 leaf = path->nodes[0];
4062 slot = path->slots[0];
4063
4064 nritems = btrfs_header_nritems(leaf);
4065 data_end = leaf_data_end(leaf);
4066 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4067
4068 if (btrfs_leaf_free_space(leaf) < total_size) {
4069 btrfs_print_leaf(leaf);
4070 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4071 total_size, btrfs_leaf_free_space(leaf));
4072 BUG();
4073 }
4074
4075 btrfs_init_map_token(&token, leaf);
4076 if (slot != nritems) {
4077 unsigned int old_data = btrfs_item_data_end(leaf, slot);
4078
4079 if (old_data < data_end) {
4080 btrfs_print_leaf(leaf);
4081 btrfs_crit(fs_info,
4082 "item at slot %d with data offset %u beyond data end of leaf %u",
4083 slot, old_data, data_end);
4084 BUG();
4085 }
4086 /*
4087 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4088 */
4089 /* first correct the data pointers */
4090 for (i = slot; i < nritems; i++) {
4091 u32 ioff;
4092
4093 ioff = btrfs_token_item_offset(&token, i);
4094 btrfs_set_token_item_offset(&token, i,
4095 ioff - batch->total_data_size);
4096 }
4097 /* shift the items */
4098 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + batch->nr),
4099 btrfs_item_nr_offset(slot),
4100 (nritems - slot) * sizeof(struct btrfs_item));
4101
4102 /* shift the data */
4103 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4104 data_end - batch->total_data_size,
4105 BTRFS_LEAF_DATA_OFFSET + data_end,
4106 old_data - data_end);
4107 data_end = old_data;
4108 }
4109
4110 /* setup the item for the new data */
4111 for (i = 0; i < batch->nr; i++) {
4112 btrfs_cpu_key_to_disk(&disk_key, &batch->keys[i]);
4113 btrfs_set_item_key(leaf, &disk_key, slot + i);
4114 data_end -= batch->data_sizes[i];
4115 btrfs_set_token_item_offset(&token, slot + i, data_end);
4116 btrfs_set_token_item_size(&token, slot + i, batch->data_sizes[i]);
4117 }
4118
4119 btrfs_set_header_nritems(leaf, nritems + batch->nr);
4120 btrfs_mark_buffer_dirty(leaf);
4121
4122 if (btrfs_leaf_free_space(leaf) < 0) {
4123 btrfs_print_leaf(leaf);
4124 BUG();
4125 }
4126 }
4127
4128 /*
4129 * Insert a new item into a leaf.
4130 *
4131 * @root: The root of the btree.
4132 * @path: A path pointing to the target leaf and slot.
4133 * @key: The key of the new item.
4134 * @data_size: The size of the data associated with the new key.
4135 */
btrfs_setup_item_for_insert(struct btrfs_root * root,struct btrfs_path * path,const struct btrfs_key * key,u32 data_size)4136 void btrfs_setup_item_for_insert(struct btrfs_root *root,
4137 struct btrfs_path *path,
4138 const struct btrfs_key *key,
4139 u32 data_size)
4140 {
4141 struct btrfs_item_batch batch;
4142
4143 batch.keys = key;
4144 batch.data_sizes = &data_size;
4145 batch.total_data_size = data_size;
4146 batch.nr = 1;
4147
4148 setup_items_for_insert(root, path, &batch);
4149 }
4150
4151 /*
4152 * Given a key and some data, insert items into the tree.
4153 * This does all the path init required, making room in the tree if needed.
4154 */
btrfs_insert_empty_items(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,const struct btrfs_item_batch * batch)4155 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4156 struct btrfs_root *root,
4157 struct btrfs_path *path,
4158 const struct btrfs_item_batch *batch)
4159 {
4160 int ret = 0;
4161 int slot;
4162 u32 total_size;
4163
4164 total_size = batch->total_data_size + (batch->nr * sizeof(struct btrfs_item));
4165 ret = btrfs_search_slot(trans, root, &batch->keys[0], path, total_size, 1);
4166 if (ret == 0)
4167 return -EEXIST;
4168 if (ret < 0)
4169 return ret;
4170
4171 slot = path->slots[0];
4172 BUG_ON(slot < 0);
4173
4174 setup_items_for_insert(root, path, batch);
4175 return 0;
4176 }
4177
4178 /*
4179 * Given a key and some data, insert an item into the tree.
4180 * This does all the path init required, making room in the tree if needed.
4181 */
btrfs_insert_item(struct btrfs_trans_handle * trans,struct btrfs_root * root,const struct btrfs_key * cpu_key,void * data,u32 data_size)4182 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4183 const struct btrfs_key *cpu_key, void *data,
4184 u32 data_size)
4185 {
4186 int ret = 0;
4187 struct btrfs_path *path;
4188 struct extent_buffer *leaf;
4189 unsigned long ptr;
4190
4191 path = btrfs_alloc_path();
4192 if (!path)
4193 return -ENOMEM;
4194 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4195 if (!ret) {
4196 leaf = path->nodes[0];
4197 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4198 write_extent_buffer(leaf, data, ptr, data_size);
4199 btrfs_mark_buffer_dirty(leaf);
4200 }
4201 btrfs_free_path(path);
4202 return ret;
4203 }
4204
4205 /*
4206 * This function duplicates an item, giving 'new_key' to the new item.
4207 * It guarantees both items live in the same tree leaf and the new item is
4208 * contiguous with the original item.
4209 *
4210 * This allows us to split a file extent in place, keeping a lock on the leaf
4211 * the entire time.
4212 */
btrfs_duplicate_item(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,const struct btrfs_key * new_key)4213 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4214 struct btrfs_root *root,
4215 struct btrfs_path *path,
4216 const struct btrfs_key *new_key)
4217 {
4218 struct extent_buffer *leaf;
4219 int ret;
4220 u32 item_size;
4221
4222 leaf = path->nodes[0];
4223 item_size = btrfs_item_size(leaf, path->slots[0]);
4224 ret = setup_leaf_for_split(trans, root, path,
4225 item_size + sizeof(struct btrfs_item));
4226 if (ret)
4227 return ret;
4228
4229 path->slots[0]++;
4230 btrfs_setup_item_for_insert(root, path, new_key, item_size);
4231 leaf = path->nodes[0];
4232 memcpy_extent_buffer(leaf,
4233 btrfs_item_ptr_offset(leaf, path->slots[0]),
4234 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4235 item_size);
4236 return 0;
4237 }
4238
4239 /*
4240 * delete the pointer from a given node.
4241 *
4242 * the tree should have been previously balanced so the deletion does not
4243 * empty a node.
4244 */
del_ptr(struct btrfs_root * root,struct btrfs_path * path,int level,int slot)4245 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4246 int level, int slot)
4247 {
4248 struct extent_buffer *parent = path->nodes[level];
4249 u32 nritems;
4250 int ret;
4251
4252 nritems = btrfs_header_nritems(parent);
4253 if (slot != nritems - 1) {
4254 if (level) {
4255 ret = btrfs_tree_mod_log_insert_move(parent, slot,
4256 slot + 1, nritems - slot - 1);
4257 BUG_ON(ret < 0);
4258 }
4259 memmove_extent_buffer(parent,
4260 btrfs_node_key_ptr_offset(slot),
4261 btrfs_node_key_ptr_offset(slot + 1),
4262 sizeof(struct btrfs_key_ptr) *
4263 (nritems - slot - 1));
4264 } else if (level) {
4265 ret = btrfs_tree_mod_log_insert_key(parent, slot,
4266 BTRFS_MOD_LOG_KEY_REMOVE, GFP_NOFS);
4267 BUG_ON(ret < 0);
4268 }
4269
4270 nritems--;
4271 btrfs_set_header_nritems(parent, nritems);
4272 if (nritems == 0 && parent == root->node) {
4273 BUG_ON(btrfs_header_level(root->node) != 1);
4274 /* just turn the root into a leaf and break */
4275 btrfs_set_header_level(root->node, 0);
4276 } else if (slot == 0) {
4277 struct btrfs_disk_key disk_key;
4278
4279 btrfs_node_key(parent, &disk_key, 0);
4280 fixup_low_keys(path, &disk_key, level + 1);
4281 }
4282 btrfs_mark_buffer_dirty(parent);
4283 }
4284
4285 /*
4286 * a helper function to delete the leaf pointed to by path->slots[1] and
4287 * path->nodes[1].
4288 *
4289 * This deletes the pointer in path->nodes[1] and frees the leaf
4290 * block extent. zero is returned if it all worked out, < 0 otherwise.
4291 *
4292 * The path must have already been setup for deleting the leaf, including
4293 * all the proper balancing. path->nodes[1] must be locked.
4294 */
btrfs_del_leaf(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,struct extent_buffer * leaf)4295 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4296 struct btrfs_root *root,
4297 struct btrfs_path *path,
4298 struct extent_buffer *leaf)
4299 {
4300 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4301 del_ptr(root, path, 1, path->slots[1]);
4302
4303 /*
4304 * btrfs_free_extent is expensive, we want to make sure we
4305 * aren't holding any locks when we call it
4306 */
4307 btrfs_unlock_up_safe(path, 0);
4308
4309 root_sub_used(root, leaf->len);
4310
4311 atomic_inc(&leaf->refs);
4312 btrfs_free_tree_block(trans, btrfs_root_id(root), leaf, 0, 1);
4313 free_extent_buffer_stale(leaf);
4314 }
4315 /*
4316 * delete the item at the leaf level in path. If that empties
4317 * the leaf, remove it from the tree
4318 */
btrfs_del_items(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,int slot,int nr)4319 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4320 struct btrfs_path *path, int slot, int nr)
4321 {
4322 struct btrfs_fs_info *fs_info = root->fs_info;
4323 struct extent_buffer *leaf;
4324 int ret = 0;
4325 int wret;
4326 u32 nritems;
4327
4328 leaf = path->nodes[0];
4329 nritems = btrfs_header_nritems(leaf);
4330
4331 if (slot + nr != nritems) {
4332 const u32 last_off = btrfs_item_offset(leaf, slot + nr - 1);
4333 const int data_end = leaf_data_end(leaf);
4334 struct btrfs_map_token token;
4335 u32 dsize = 0;
4336 int i;
4337
4338 for (i = 0; i < nr; i++)
4339 dsize += btrfs_item_size(leaf, slot + i);
4340
4341 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4342 data_end + dsize,
4343 BTRFS_LEAF_DATA_OFFSET + data_end,
4344 last_off - data_end);
4345
4346 btrfs_init_map_token(&token, leaf);
4347 for (i = slot + nr; i < nritems; i++) {
4348 u32 ioff;
4349
4350 ioff = btrfs_token_item_offset(&token, i);
4351 btrfs_set_token_item_offset(&token, i, ioff + dsize);
4352 }
4353
4354 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4355 btrfs_item_nr_offset(slot + nr),
4356 sizeof(struct btrfs_item) *
4357 (nritems - slot - nr));
4358 }
4359 btrfs_set_header_nritems(leaf, nritems - nr);
4360 nritems -= nr;
4361
4362 /* delete the leaf if we've emptied it */
4363 if (nritems == 0) {
4364 if (leaf == root->node) {
4365 btrfs_set_header_level(leaf, 0);
4366 } else {
4367 btrfs_clean_tree_block(leaf);
4368 btrfs_del_leaf(trans, root, path, leaf);
4369 }
4370 } else {
4371 int used = leaf_space_used(leaf, 0, nritems);
4372 if (slot == 0) {
4373 struct btrfs_disk_key disk_key;
4374
4375 btrfs_item_key(leaf, &disk_key, 0);
4376 fixup_low_keys(path, &disk_key, 1);
4377 }
4378
4379 /*
4380 * Try to delete the leaf if it is mostly empty. We do this by
4381 * trying to move all its items into its left and right neighbours.
4382 * If we can't move all the items, then we don't delete it - it's
4383 * not ideal, but future insertions might fill the leaf with more
4384 * items, or items from other leaves might be moved later into our
4385 * leaf due to deletions on those leaves.
4386 */
4387 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4388 u32 min_push_space;
4389
4390 /* push_leaf_left fixes the path.
4391 * make sure the path still points to our leaf
4392 * for possible call to del_ptr below
4393 */
4394 slot = path->slots[1];
4395 atomic_inc(&leaf->refs);
4396 /*
4397 * We want to be able to at least push one item to the
4398 * left neighbour leaf, and that's the first item.
4399 */
4400 min_push_space = sizeof(struct btrfs_item) +
4401 btrfs_item_size(leaf, 0);
4402 wret = push_leaf_left(trans, root, path, 0,
4403 min_push_space, 1, (u32)-1);
4404 if (wret < 0 && wret != -ENOSPC)
4405 ret = wret;
4406
4407 if (path->nodes[0] == leaf &&
4408 btrfs_header_nritems(leaf)) {
4409 /*
4410 * If we were not able to push all items from our
4411 * leaf to its left neighbour, then attempt to
4412 * either push all the remaining items to the
4413 * right neighbour or none. There's no advantage
4414 * in pushing only some items, instead of all, as
4415 * it's pointless to end up with a leaf having
4416 * too few items while the neighbours can be full
4417 * or nearly full.
4418 */
4419 nritems = btrfs_header_nritems(leaf);
4420 min_push_space = leaf_space_used(leaf, 0, nritems);
4421 wret = push_leaf_right(trans, root, path, 0,
4422 min_push_space, 1, 0);
4423 if (wret < 0 && wret != -ENOSPC)
4424 ret = wret;
4425 }
4426
4427 if (btrfs_header_nritems(leaf) == 0) {
4428 path->slots[1] = slot;
4429 btrfs_del_leaf(trans, root, path, leaf);
4430 free_extent_buffer(leaf);
4431 ret = 0;
4432 } else {
4433 /* if we're still in the path, make sure
4434 * we're dirty. Otherwise, one of the
4435 * push_leaf functions must have already
4436 * dirtied this buffer
4437 */
4438 if (path->nodes[0] == leaf)
4439 btrfs_mark_buffer_dirty(leaf);
4440 free_extent_buffer(leaf);
4441 }
4442 } else {
4443 btrfs_mark_buffer_dirty(leaf);
4444 }
4445 }
4446 return ret;
4447 }
4448
4449 /*
4450 * search the tree again to find a leaf with lesser keys
4451 * returns 0 if it found something or 1 if there are no lesser leaves.
4452 * returns < 0 on io errors.
4453 *
4454 * This may release the path, and so you may lose any locks held at the
4455 * time you call it.
4456 */
btrfs_prev_leaf(struct btrfs_root * root,struct btrfs_path * path)4457 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4458 {
4459 struct btrfs_key key;
4460 struct btrfs_key orig_key;
4461 struct btrfs_disk_key found_key;
4462 int ret;
4463
4464 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4465 orig_key = key;
4466
4467 if (key.offset > 0) {
4468 key.offset--;
4469 } else if (key.type > 0) {
4470 key.type--;
4471 key.offset = (u64)-1;
4472 } else if (key.objectid > 0) {
4473 key.objectid--;
4474 key.type = (u8)-1;
4475 key.offset = (u64)-1;
4476 } else {
4477 return 1;
4478 }
4479
4480 btrfs_release_path(path);
4481 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4482 if (ret <= 0)
4483 return ret;
4484
4485 /*
4486 * Previous key not found. Even if we were at slot 0 of the leaf we had
4487 * before releasing the path and calling btrfs_search_slot(), we now may
4488 * be in a slot pointing to the same original key - this can happen if
4489 * after we released the path, one of more items were moved from a
4490 * sibling leaf into the front of the leaf we had due to an insertion
4491 * (see push_leaf_right()).
4492 * If we hit this case and our slot is > 0 and just decrement the slot
4493 * so that the caller does not process the same key again, which may or
4494 * may not break the caller, depending on its logic.
4495 */
4496 if (path->slots[0] < btrfs_header_nritems(path->nodes[0])) {
4497 btrfs_item_key(path->nodes[0], &found_key, path->slots[0]);
4498 ret = comp_keys(&found_key, &orig_key);
4499 if (ret == 0) {
4500 if (path->slots[0] > 0) {
4501 path->slots[0]--;
4502 return 0;
4503 }
4504 /*
4505 * At slot 0, same key as before, it means orig_key is
4506 * the lowest, leftmost, key in the tree. We're done.
4507 */
4508 return 1;
4509 }
4510 }
4511
4512 btrfs_item_key(path->nodes[0], &found_key, 0);
4513 ret = comp_keys(&found_key, &key);
4514 /*
4515 * We might have had an item with the previous key in the tree right
4516 * before we released our path. And after we released our path, that
4517 * item might have been pushed to the first slot (0) of the leaf we
4518 * were holding due to a tree balance. Alternatively, an item with the
4519 * previous key can exist as the only element of a leaf (big fat item).
4520 * Therefore account for these 2 cases, so that our callers (like
4521 * btrfs_previous_item) don't miss an existing item with a key matching
4522 * the previous key we computed above.
4523 */
4524 if (ret <= 0)
4525 return 0;
4526 return 1;
4527 }
4528
4529 /*
4530 * A helper function to walk down the tree starting at min_key, and looking
4531 * for nodes or leaves that are have a minimum transaction id.
4532 * This is used by the btree defrag code, and tree logging
4533 *
4534 * This does not cow, but it does stuff the starting key it finds back
4535 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4536 * key and get a writable path.
4537 *
4538 * This honors path->lowest_level to prevent descent past a given level
4539 * of the tree.
4540 *
4541 * min_trans indicates the oldest transaction that you are interested
4542 * in walking through. Any nodes or leaves older than min_trans are
4543 * skipped over (without reading them).
4544 *
4545 * returns zero if something useful was found, < 0 on error and 1 if there
4546 * was nothing in the tree that matched the search criteria.
4547 */
btrfs_search_forward(struct btrfs_root * root,struct btrfs_key * min_key,struct btrfs_path * path,u64 min_trans)4548 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4549 struct btrfs_path *path,
4550 u64 min_trans)
4551 {
4552 struct extent_buffer *cur;
4553 struct btrfs_key found_key;
4554 int slot;
4555 int sret;
4556 u32 nritems;
4557 int level;
4558 int ret = 1;
4559 int keep_locks = path->keep_locks;
4560
4561 ASSERT(!path->nowait);
4562 path->keep_locks = 1;
4563 again:
4564 cur = btrfs_read_lock_root_node(root);
4565 level = btrfs_header_level(cur);
4566 WARN_ON(path->nodes[level]);
4567 path->nodes[level] = cur;
4568 path->locks[level] = BTRFS_READ_LOCK;
4569
4570 if (btrfs_header_generation(cur) < min_trans) {
4571 ret = 1;
4572 goto out;
4573 }
4574 while (1) {
4575 nritems = btrfs_header_nritems(cur);
4576 level = btrfs_header_level(cur);
4577 sret = btrfs_bin_search(cur, min_key, &slot);
4578 if (sret < 0) {
4579 ret = sret;
4580 goto out;
4581 }
4582
4583 /* at the lowest level, we're done, setup the path and exit */
4584 if (level == path->lowest_level) {
4585 if (slot >= nritems)
4586 goto find_next_key;
4587 ret = 0;
4588 path->slots[level] = slot;
4589 btrfs_item_key_to_cpu(cur, &found_key, slot);
4590 goto out;
4591 }
4592 if (sret && slot > 0)
4593 slot--;
4594 /*
4595 * check this node pointer against the min_trans parameters.
4596 * If it is too old, skip to the next one.
4597 */
4598 while (slot < nritems) {
4599 u64 gen;
4600
4601 gen = btrfs_node_ptr_generation(cur, slot);
4602 if (gen < min_trans) {
4603 slot++;
4604 continue;
4605 }
4606 break;
4607 }
4608 find_next_key:
4609 /*
4610 * we didn't find a candidate key in this node, walk forward
4611 * and find another one
4612 */
4613 if (slot >= nritems) {
4614 path->slots[level] = slot;
4615 sret = btrfs_find_next_key(root, path, min_key, level,
4616 min_trans);
4617 if (sret == 0) {
4618 btrfs_release_path(path);
4619 goto again;
4620 } else {
4621 goto out;
4622 }
4623 }
4624 /* save our key for returning back */
4625 btrfs_node_key_to_cpu(cur, &found_key, slot);
4626 path->slots[level] = slot;
4627 if (level == path->lowest_level) {
4628 ret = 0;
4629 goto out;
4630 }
4631 cur = btrfs_read_node_slot(cur, slot);
4632 if (IS_ERR(cur)) {
4633 ret = PTR_ERR(cur);
4634 goto out;
4635 }
4636
4637 btrfs_tree_read_lock(cur);
4638
4639 path->locks[level - 1] = BTRFS_READ_LOCK;
4640 path->nodes[level - 1] = cur;
4641 unlock_up(path, level, 1, 0, NULL);
4642 }
4643 out:
4644 path->keep_locks = keep_locks;
4645 if (ret == 0) {
4646 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4647 memcpy(min_key, &found_key, sizeof(found_key));
4648 }
4649 return ret;
4650 }
4651
4652 /*
4653 * this is similar to btrfs_next_leaf, but does not try to preserve
4654 * and fixup the path. It looks for and returns the next key in the
4655 * tree based on the current path and the min_trans parameters.
4656 *
4657 * 0 is returned if another key is found, < 0 if there are any errors
4658 * and 1 is returned if there are no higher keys in the tree
4659 *
4660 * path->keep_locks should be set to 1 on the search made before
4661 * calling this function.
4662 */
btrfs_find_next_key(struct btrfs_root * root,struct btrfs_path * path,struct btrfs_key * key,int level,u64 min_trans)4663 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4664 struct btrfs_key *key, int level, u64 min_trans)
4665 {
4666 int slot;
4667 struct extent_buffer *c;
4668
4669 WARN_ON(!path->keep_locks && !path->skip_locking);
4670 while (level < BTRFS_MAX_LEVEL) {
4671 if (!path->nodes[level])
4672 return 1;
4673
4674 slot = path->slots[level] + 1;
4675 c = path->nodes[level];
4676 next:
4677 if (slot >= btrfs_header_nritems(c)) {
4678 int ret;
4679 int orig_lowest;
4680 struct btrfs_key cur_key;
4681 if (level + 1 >= BTRFS_MAX_LEVEL ||
4682 !path->nodes[level + 1])
4683 return 1;
4684
4685 if (path->locks[level + 1] || path->skip_locking) {
4686 level++;
4687 continue;
4688 }
4689
4690 slot = btrfs_header_nritems(c) - 1;
4691 if (level == 0)
4692 btrfs_item_key_to_cpu(c, &cur_key, slot);
4693 else
4694 btrfs_node_key_to_cpu(c, &cur_key, slot);
4695
4696 orig_lowest = path->lowest_level;
4697 btrfs_release_path(path);
4698 path->lowest_level = level;
4699 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4700 0, 0);
4701 path->lowest_level = orig_lowest;
4702 if (ret < 0)
4703 return ret;
4704
4705 c = path->nodes[level];
4706 slot = path->slots[level];
4707 if (ret == 0)
4708 slot++;
4709 goto next;
4710 }
4711
4712 if (level == 0)
4713 btrfs_item_key_to_cpu(c, key, slot);
4714 else {
4715 u64 gen = btrfs_node_ptr_generation(c, slot);
4716
4717 if (gen < min_trans) {
4718 slot++;
4719 goto next;
4720 }
4721 btrfs_node_key_to_cpu(c, key, slot);
4722 }
4723 return 0;
4724 }
4725 return 1;
4726 }
4727
btrfs_next_old_leaf(struct btrfs_root * root,struct btrfs_path * path,u64 time_seq)4728 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4729 u64 time_seq)
4730 {
4731 int slot;
4732 int level;
4733 struct extent_buffer *c;
4734 struct extent_buffer *next;
4735 struct btrfs_fs_info *fs_info = root->fs_info;
4736 struct btrfs_key key;
4737 bool need_commit_sem = false;
4738 u32 nritems;
4739 int ret;
4740 int i;
4741
4742 /*
4743 * The nowait semantics are used only for write paths, where we don't
4744 * use the tree mod log and sequence numbers.
4745 */
4746 if (time_seq)
4747 ASSERT(!path->nowait);
4748
4749 nritems = btrfs_header_nritems(path->nodes[0]);
4750 if (nritems == 0)
4751 return 1;
4752
4753 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4754 again:
4755 level = 1;
4756 next = NULL;
4757 btrfs_release_path(path);
4758
4759 path->keep_locks = 1;
4760
4761 if (time_seq) {
4762 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4763 } else {
4764 if (path->need_commit_sem) {
4765 path->need_commit_sem = 0;
4766 need_commit_sem = true;
4767 if (path->nowait) {
4768 if (!down_read_trylock(&fs_info->commit_root_sem)) {
4769 ret = -EAGAIN;
4770 goto done;
4771 }
4772 } else {
4773 down_read(&fs_info->commit_root_sem);
4774 }
4775 }
4776 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4777 }
4778 path->keep_locks = 0;
4779
4780 if (ret < 0)
4781 goto done;
4782
4783 nritems = btrfs_header_nritems(path->nodes[0]);
4784 /*
4785 * by releasing the path above we dropped all our locks. A balance
4786 * could have added more items next to the key that used to be
4787 * at the very end of the block. So, check again here and
4788 * advance the path if there are now more items available.
4789 */
4790 if (nritems > 0 && path->slots[0] < nritems - 1) {
4791 if (ret == 0)
4792 path->slots[0]++;
4793 ret = 0;
4794 goto done;
4795 }
4796 /*
4797 * So the above check misses one case:
4798 * - after releasing the path above, someone has removed the item that
4799 * used to be at the very end of the block, and balance between leafs
4800 * gets another one with bigger key.offset to replace it.
4801 *
4802 * This one should be returned as well, or we can get leaf corruption
4803 * later(esp. in __btrfs_drop_extents()).
4804 *
4805 * And a bit more explanation about this check,
4806 * with ret > 0, the key isn't found, the path points to the slot
4807 * where it should be inserted, so the path->slots[0] item must be the
4808 * bigger one.
4809 */
4810 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4811 ret = 0;
4812 goto done;
4813 }
4814
4815 while (level < BTRFS_MAX_LEVEL) {
4816 if (!path->nodes[level]) {
4817 ret = 1;
4818 goto done;
4819 }
4820
4821 slot = path->slots[level] + 1;
4822 c = path->nodes[level];
4823 if (slot >= btrfs_header_nritems(c)) {
4824 level++;
4825 if (level == BTRFS_MAX_LEVEL) {
4826 ret = 1;
4827 goto done;
4828 }
4829 continue;
4830 }
4831
4832
4833 /*
4834 * Our current level is where we're going to start from, and to
4835 * make sure lockdep doesn't complain we need to drop our locks
4836 * and nodes from 0 to our current level.
4837 */
4838 for (i = 0; i < level; i++) {
4839 if (path->locks[level]) {
4840 btrfs_tree_read_unlock(path->nodes[i]);
4841 path->locks[i] = 0;
4842 }
4843 free_extent_buffer(path->nodes[i]);
4844 path->nodes[i] = NULL;
4845 }
4846
4847 next = c;
4848 ret = read_block_for_search(root, path, &next, level,
4849 slot, &key);
4850 if (ret == -EAGAIN && !path->nowait)
4851 goto again;
4852
4853 if (ret < 0) {
4854 btrfs_release_path(path);
4855 goto done;
4856 }
4857
4858 if (!path->skip_locking) {
4859 ret = btrfs_try_tree_read_lock(next);
4860 if (!ret && path->nowait) {
4861 ret = -EAGAIN;
4862 goto done;
4863 }
4864 if (!ret && time_seq) {
4865 /*
4866 * If we don't get the lock, we may be racing
4867 * with push_leaf_left, holding that lock while
4868 * itself waiting for the leaf we've currently
4869 * locked. To solve this situation, we give up
4870 * on our lock and cycle.
4871 */
4872 free_extent_buffer(next);
4873 btrfs_release_path(path);
4874 cond_resched();
4875 goto again;
4876 }
4877 if (!ret)
4878 btrfs_tree_read_lock(next);
4879 }
4880 break;
4881 }
4882 path->slots[level] = slot;
4883 while (1) {
4884 level--;
4885 path->nodes[level] = next;
4886 path->slots[level] = 0;
4887 if (!path->skip_locking)
4888 path->locks[level] = BTRFS_READ_LOCK;
4889 if (!level)
4890 break;
4891
4892 ret = read_block_for_search(root, path, &next, level,
4893 0, &key);
4894 if (ret == -EAGAIN && !path->nowait)
4895 goto again;
4896
4897 if (ret < 0) {
4898 btrfs_release_path(path);
4899 goto done;
4900 }
4901
4902 if (!path->skip_locking) {
4903 if (path->nowait) {
4904 if (!btrfs_try_tree_read_lock(next)) {
4905 ret = -EAGAIN;
4906 goto done;
4907 }
4908 } else {
4909 btrfs_tree_read_lock(next);
4910 }
4911 }
4912 }
4913 ret = 0;
4914 done:
4915 unlock_up(path, 0, 1, 0, NULL);
4916 if (need_commit_sem) {
4917 int ret2;
4918
4919 path->need_commit_sem = 1;
4920 ret2 = finish_need_commit_sem_search(path);
4921 up_read(&fs_info->commit_root_sem);
4922 if (ret2)
4923 ret = ret2;
4924 }
4925
4926 return ret;
4927 }
4928
4929 /*
4930 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4931 * searching until it gets past min_objectid or finds an item of 'type'
4932 *
4933 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4934 */
btrfs_previous_item(struct btrfs_root * root,struct btrfs_path * path,u64 min_objectid,int type)4935 int btrfs_previous_item(struct btrfs_root *root,
4936 struct btrfs_path *path, u64 min_objectid,
4937 int type)
4938 {
4939 struct btrfs_key found_key;
4940 struct extent_buffer *leaf;
4941 u32 nritems;
4942 int ret;
4943
4944 while (1) {
4945 if (path->slots[0] == 0) {
4946 ret = btrfs_prev_leaf(root, path);
4947 if (ret != 0)
4948 return ret;
4949 } else {
4950 path->slots[0]--;
4951 }
4952 leaf = path->nodes[0];
4953 nritems = btrfs_header_nritems(leaf);
4954 if (nritems == 0)
4955 return 1;
4956 if (path->slots[0] == nritems)
4957 path->slots[0]--;
4958
4959 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4960 if (found_key.objectid < min_objectid)
4961 break;
4962 if (found_key.type == type)
4963 return 0;
4964 if (found_key.objectid == min_objectid &&
4965 found_key.type < type)
4966 break;
4967 }
4968 return 1;
4969 }
4970
4971 /*
4972 * search in extent tree to find a previous Metadata/Data extent item with
4973 * min objecitd.
4974 *
4975 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4976 */
btrfs_previous_extent_item(struct btrfs_root * root,struct btrfs_path * path,u64 min_objectid)4977 int btrfs_previous_extent_item(struct btrfs_root *root,
4978 struct btrfs_path *path, u64 min_objectid)
4979 {
4980 struct btrfs_key found_key;
4981 struct extent_buffer *leaf;
4982 u32 nritems;
4983 int ret;
4984
4985 while (1) {
4986 if (path->slots[0] == 0) {
4987 ret = btrfs_prev_leaf(root, path);
4988 if (ret != 0)
4989 return ret;
4990 } else {
4991 path->slots[0]--;
4992 }
4993 leaf = path->nodes[0];
4994 nritems = btrfs_header_nritems(leaf);
4995 if (nritems == 0)
4996 return 1;
4997 if (path->slots[0] == nritems)
4998 path->slots[0]--;
4999
5000 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5001 if (found_key.objectid < min_objectid)
5002 break;
5003 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5004 found_key.type == BTRFS_METADATA_ITEM_KEY)
5005 return 0;
5006 if (found_key.objectid == min_objectid &&
5007 found_key.type < BTRFS_EXTENT_ITEM_KEY)
5008 break;
5009 }
5010 return 1;
5011 }
5012