1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2007,2008 Oracle. All rights reserved.
6 #include <linux/sched.h>
7 #include <linux/slab.h>
8 #include <linux/rbtree.h>
12 #include "transaction.h"
13 #include "print-tree.h"
17 #include "tree-mod-log.h"
19 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
20 *root, struct btrfs_path *path, int level);
21 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
22 const struct btrfs_key *ins_key, struct btrfs_path *path,
23 int data_size, int extend);
24 static int push_node_left(struct btrfs_trans_handle *trans,
25 struct extent_buffer *dst,
26 struct extent_buffer *src, int empty);
27 static int balance_node_right(struct btrfs_trans_handle *trans,
28 struct extent_buffer *dst_buf,
29 struct extent_buffer *src_buf);
30 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
33 static const struct btrfs_csums {
36 const char driver[12];
38 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
39 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
40 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
41 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
42 .driver = "blake2b-256" },
45 int btrfs_super_csum_size(const struct btrfs_super_block *s)
47 u16 t = btrfs_super_csum_type(s);
49 * csum type is validated at mount time
51 return btrfs_csums[t].size;
54 const char *btrfs_super_csum_name(u16 csum_type)
56 /* csum type is validated at mount time */
57 return btrfs_csums[csum_type].name;
61 * Return driver name if defined, otherwise the name that's also a valid driver
64 const char *btrfs_super_csum_driver(u16 csum_type)
66 /* csum type is validated at mount time */
67 return btrfs_csums[csum_type].driver[0] ?
68 btrfs_csums[csum_type].driver :
69 btrfs_csums[csum_type].name;
72 size_t __attribute_const__ btrfs_get_num_csums(void)
74 return ARRAY_SIZE(btrfs_csums);
77 struct btrfs_path *btrfs_alloc_path(void)
79 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
82 /* this also releases the path */
83 void btrfs_free_path(struct btrfs_path *p)
87 btrfs_release_path(p);
88 kmem_cache_free(btrfs_path_cachep, p);
92 * path release drops references on the extent buffers in the path
93 * and it drops any locks held by this path
95 * It is safe to call this on paths that no locks or extent buffers held.
97 noinline void btrfs_release_path(struct btrfs_path *p)
101 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
106 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
109 free_extent_buffer(p->nodes[i]);
115 * safely gets a reference on the root node of a tree. A lock
116 * is not taken, so a concurrent writer may put a different node
117 * at the root of the tree. See btrfs_lock_root_node for the
120 * The extent buffer returned by this has a reference taken, so
121 * it won't disappear. It may stop being the root of the tree
122 * at any time because there are no locks held.
124 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
126 struct extent_buffer *eb;
130 eb = rcu_dereference(root->node);
133 * RCU really hurts here, we could free up the root node because
134 * it was COWed but we may not get the new root node yet so do
135 * the inc_not_zero dance and if it doesn't work then
136 * synchronize_rcu and try again.
138 if (atomic_inc_not_zero(&eb->refs)) {
149 * Cowonly root (not-shareable trees, everything not subvolume or reloc roots),
150 * just get put onto a simple dirty list. Transaction walks this list to make
151 * sure they get properly updated on disk.
153 static void add_root_to_dirty_list(struct btrfs_root *root)
155 struct btrfs_fs_info *fs_info = root->fs_info;
157 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
158 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
161 spin_lock(&fs_info->trans_lock);
162 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
163 /* Want the extent tree to be the last on the list */
164 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
165 list_move_tail(&root->dirty_list,
166 &fs_info->dirty_cowonly_roots);
168 list_move(&root->dirty_list,
169 &fs_info->dirty_cowonly_roots);
171 spin_unlock(&fs_info->trans_lock);
175 * used by snapshot creation to make a copy of a root for a tree with
176 * a given objectid. The buffer with the new root node is returned in
177 * cow_ret, and this func returns zero on success or a negative error code.
179 int btrfs_copy_root(struct btrfs_trans_handle *trans,
180 struct btrfs_root *root,
181 struct extent_buffer *buf,
182 struct extent_buffer **cow_ret, u64 new_root_objectid)
184 struct btrfs_fs_info *fs_info = root->fs_info;
185 struct extent_buffer *cow;
188 struct btrfs_disk_key disk_key;
190 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
191 trans->transid != fs_info->running_transaction->transid);
192 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
193 trans->transid != root->last_trans);
195 level = btrfs_header_level(buf);
197 btrfs_item_key(buf, &disk_key, 0);
199 btrfs_node_key(buf, &disk_key, 0);
201 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
202 &disk_key, level, buf->start, 0,
203 BTRFS_NESTING_NEW_ROOT);
207 copy_extent_buffer_full(cow, buf);
208 btrfs_set_header_bytenr(cow, cow->start);
209 btrfs_set_header_generation(cow, trans->transid);
210 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
211 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
212 BTRFS_HEADER_FLAG_RELOC);
213 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
214 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
216 btrfs_set_header_owner(cow, new_root_objectid);
218 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
220 WARN_ON(btrfs_header_generation(buf) > trans->transid);
221 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
222 ret = btrfs_inc_ref(trans, root, cow, 1);
224 ret = btrfs_inc_ref(trans, root, cow, 0);
226 btrfs_tree_unlock(cow);
227 free_extent_buffer(cow);
228 btrfs_abort_transaction(trans, ret);
232 btrfs_mark_buffer_dirty(cow);
238 * check if the tree block can be shared by multiple trees
240 int btrfs_block_can_be_shared(struct btrfs_root *root,
241 struct extent_buffer *buf)
244 * Tree blocks not in shareable trees and tree roots are never shared.
245 * If a block was allocated after the last snapshot and the block was
246 * not allocated by tree relocation, we know the block is not shared.
248 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
249 buf != root->node && buf != root->commit_root &&
250 (btrfs_header_generation(buf) <=
251 btrfs_root_last_snapshot(&root->root_item) ||
252 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
258 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
259 struct btrfs_root *root,
260 struct extent_buffer *buf,
261 struct extent_buffer *cow,
264 struct btrfs_fs_info *fs_info = root->fs_info;
272 * Backrefs update rules:
274 * Always use full backrefs for extent pointers in tree block
275 * allocated by tree relocation.
277 * If a shared tree block is no longer referenced by its owner
278 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
279 * use full backrefs for extent pointers in tree block.
281 * If a tree block is been relocating
282 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
283 * use full backrefs for extent pointers in tree block.
284 * The reason for this is some operations (such as drop tree)
285 * are only allowed for blocks use full backrefs.
288 if (btrfs_block_can_be_shared(root, buf)) {
289 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
290 btrfs_header_level(buf), 1,
296 btrfs_handle_fs_error(fs_info, ret, NULL);
301 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
302 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
303 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
308 owner = btrfs_header_owner(buf);
309 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
310 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
313 if ((owner == root->root_key.objectid ||
314 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
315 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
316 ret = btrfs_inc_ref(trans, root, buf, 1);
320 if (root->root_key.objectid ==
321 BTRFS_TREE_RELOC_OBJECTID) {
322 ret = btrfs_dec_ref(trans, root, buf, 0);
325 ret = btrfs_inc_ref(trans, root, cow, 1);
329 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
332 if (root->root_key.objectid ==
333 BTRFS_TREE_RELOC_OBJECTID)
334 ret = btrfs_inc_ref(trans, root, cow, 1);
336 ret = btrfs_inc_ref(trans, root, cow, 0);
340 if (new_flags != 0) {
341 int level = btrfs_header_level(buf);
343 ret = btrfs_set_disk_extent_flags(trans, buf,
344 new_flags, level, 0);
349 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
350 if (root->root_key.objectid ==
351 BTRFS_TREE_RELOC_OBJECTID)
352 ret = btrfs_inc_ref(trans, root, cow, 1);
354 ret = btrfs_inc_ref(trans, root, cow, 0);
357 ret = btrfs_dec_ref(trans, root, buf, 1);
361 btrfs_clean_tree_block(buf);
368 * does the dirty work in cow of a single block. The parent block (if
369 * supplied) is updated to point to the new cow copy. The new buffer is marked
370 * dirty and returned locked. If you modify the block it needs to be marked
373 * search_start -- an allocation hint for the new block
375 * empty_size -- a hint that you plan on doing more cow. This is the size in
376 * bytes the allocator should try to find free next to the block it returns.
377 * This is just a hint and may be ignored by the allocator.
379 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
380 struct btrfs_root *root,
381 struct extent_buffer *buf,
382 struct extent_buffer *parent, int parent_slot,
383 struct extent_buffer **cow_ret,
384 u64 search_start, u64 empty_size,
385 enum btrfs_lock_nesting nest)
387 struct btrfs_fs_info *fs_info = root->fs_info;
388 struct btrfs_disk_key disk_key;
389 struct extent_buffer *cow;
393 u64 parent_start = 0;
398 btrfs_assert_tree_locked(buf);
400 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
401 trans->transid != fs_info->running_transaction->transid);
402 WARN_ON(test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
403 trans->transid != root->last_trans);
405 level = btrfs_header_level(buf);
408 btrfs_item_key(buf, &disk_key, 0);
410 btrfs_node_key(buf, &disk_key, 0);
412 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
413 parent_start = parent->start;
415 cow = btrfs_alloc_tree_block(trans, root, parent_start,
416 root->root_key.objectid, &disk_key, level,
417 search_start, empty_size, nest);
421 /* cow is set to blocking by btrfs_init_new_buffer */
423 copy_extent_buffer_full(cow, buf);
424 btrfs_set_header_bytenr(cow, cow->start);
425 btrfs_set_header_generation(cow, trans->transid);
426 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
427 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
428 BTRFS_HEADER_FLAG_RELOC);
429 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
430 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
432 btrfs_set_header_owner(cow, root->root_key.objectid);
434 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
436 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
438 btrfs_tree_unlock(cow);
439 free_extent_buffer(cow);
440 btrfs_abort_transaction(trans, ret);
444 if (test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) {
445 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
447 btrfs_tree_unlock(cow);
448 free_extent_buffer(cow);
449 btrfs_abort_transaction(trans, ret);
454 if (buf == root->node) {
455 WARN_ON(parent && parent != buf);
456 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
457 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
458 parent_start = buf->start;
460 atomic_inc(&cow->refs);
461 ret = btrfs_tree_mod_log_insert_root(root->node, cow, true);
463 rcu_assign_pointer(root->node, cow);
465 btrfs_free_tree_block(trans, root, buf, parent_start,
467 free_extent_buffer(buf);
468 add_root_to_dirty_list(root);
470 WARN_ON(trans->transid != btrfs_header_generation(parent));
471 btrfs_tree_mod_log_insert_key(parent, parent_slot,
472 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
473 btrfs_set_node_blockptr(parent, parent_slot,
475 btrfs_set_node_ptr_generation(parent, parent_slot,
477 btrfs_mark_buffer_dirty(parent);
479 ret = btrfs_tree_mod_log_free_eb(buf);
481 btrfs_tree_unlock(cow);
482 free_extent_buffer(cow);
483 btrfs_abort_transaction(trans, ret);
487 btrfs_free_tree_block(trans, root, buf, parent_start,
491 btrfs_tree_unlock(buf);
492 free_extent_buffer_stale(buf);
493 btrfs_mark_buffer_dirty(cow);
498 static inline int should_cow_block(struct btrfs_trans_handle *trans,
499 struct btrfs_root *root,
500 struct extent_buffer *buf)
502 if (btrfs_is_testing(root->fs_info))
505 /* Ensure we can see the FORCE_COW bit */
506 smp_mb__before_atomic();
509 * We do not need to cow a block if
510 * 1) this block is not created or changed in this transaction;
511 * 2) this block does not belong to TREE_RELOC tree;
512 * 3) the root is not forced COW.
514 * What is forced COW:
515 * when we create snapshot during committing the transaction,
516 * after we've finished copying src root, we must COW the shared
517 * block to ensure the metadata consistency.
519 if (btrfs_header_generation(buf) == trans->transid &&
520 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
521 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
522 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
523 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
529 * cows a single block, see __btrfs_cow_block for the real work.
530 * This version of it has extra checks so that a block isn't COWed more than
531 * once per transaction, as long as it hasn't been written yet
533 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
534 struct btrfs_root *root, struct extent_buffer *buf,
535 struct extent_buffer *parent, int parent_slot,
536 struct extent_buffer **cow_ret,
537 enum btrfs_lock_nesting nest)
539 struct btrfs_fs_info *fs_info = root->fs_info;
543 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
545 "COW'ing blocks on a fs root that's being dropped");
547 if (trans->transaction != fs_info->running_transaction)
548 WARN(1, KERN_CRIT "trans %llu running %llu\n",
550 fs_info->running_transaction->transid);
552 if (trans->transid != fs_info->generation)
553 WARN(1, KERN_CRIT "trans %llu running %llu\n",
554 trans->transid, fs_info->generation);
556 if (!should_cow_block(trans, root, buf)) {
561 search_start = buf->start & ~((u64)SZ_1G - 1);
564 * Before CoWing this block for later modification, check if it's
565 * the subtree root and do the delayed subtree trace if needed.
567 * Also We don't care about the error, as it's handled internally.
569 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
570 ret = __btrfs_cow_block(trans, root, buf, parent,
571 parent_slot, cow_ret, search_start, 0, nest);
573 trace_btrfs_cow_block(root, buf, *cow_ret);
577 ALLOW_ERROR_INJECTION(btrfs_cow_block, ERRNO);
580 * helper function for defrag to decide if two blocks pointed to by a
581 * node are actually close by
583 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
585 if (blocknr < other && other - (blocknr + blocksize) < 32768)
587 if (blocknr > other && blocknr - (other + blocksize) < 32768)
592 #ifdef __LITTLE_ENDIAN
595 * Compare two keys, on little-endian the disk order is same as CPU order and
596 * we can avoid the conversion.
598 static int comp_keys(const struct btrfs_disk_key *disk_key,
599 const struct btrfs_key *k2)
601 const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key;
603 return btrfs_comp_cpu_keys(k1, k2);
609 * compare two keys in a memcmp fashion
611 static int comp_keys(const struct btrfs_disk_key *disk,
612 const struct btrfs_key *k2)
616 btrfs_disk_key_to_cpu(&k1, disk);
618 return btrfs_comp_cpu_keys(&k1, k2);
623 * same as comp_keys only with two btrfs_key's
625 int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
627 if (k1->objectid > k2->objectid)
629 if (k1->objectid < k2->objectid)
631 if (k1->type > k2->type)
633 if (k1->type < k2->type)
635 if (k1->offset > k2->offset)
637 if (k1->offset < k2->offset)
643 * this is used by the defrag code to go through all the
644 * leaves pointed to by a node and reallocate them so that
645 * disk order is close to key order
647 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
648 struct btrfs_root *root, struct extent_buffer *parent,
649 int start_slot, u64 *last_ret,
650 struct btrfs_key *progress)
652 struct btrfs_fs_info *fs_info = root->fs_info;
653 struct extent_buffer *cur;
655 u64 search_start = *last_ret;
663 int progress_passed = 0;
664 struct btrfs_disk_key disk_key;
666 WARN_ON(trans->transaction != fs_info->running_transaction);
667 WARN_ON(trans->transid != fs_info->generation);
669 parent_nritems = btrfs_header_nritems(parent);
670 blocksize = fs_info->nodesize;
671 end_slot = parent_nritems - 1;
673 if (parent_nritems <= 1)
676 for (i = start_slot; i <= end_slot; i++) {
679 btrfs_node_key(parent, &disk_key, i);
680 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
684 blocknr = btrfs_node_blockptr(parent, i);
686 last_block = blocknr;
689 other = btrfs_node_blockptr(parent, i - 1);
690 close = close_blocks(blocknr, other, blocksize);
692 if (!close && i < end_slot) {
693 other = btrfs_node_blockptr(parent, i + 1);
694 close = close_blocks(blocknr, other, blocksize);
697 last_block = blocknr;
701 cur = btrfs_read_node_slot(parent, i);
704 if (search_start == 0)
705 search_start = last_block;
707 btrfs_tree_lock(cur);
708 err = __btrfs_cow_block(trans, root, cur, parent, i,
711 (end_slot - i) * blocksize),
714 btrfs_tree_unlock(cur);
715 free_extent_buffer(cur);
718 search_start = cur->start;
719 last_block = cur->start;
720 *last_ret = search_start;
721 btrfs_tree_unlock(cur);
722 free_extent_buffer(cur);
728 * search for key in the extent_buffer. The items start at offset p,
729 * and they are item_size apart.
731 * the slot in the array is returned via slot, and it points to
732 * the place where you would insert key if it is not found in
735 * Slot may point to total number of items if the key is bigger than
738 static noinline int generic_bin_search(struct extent_buffer *eb,
739 unsigned long p, int item_size,
740 const struct btrfs_key *key, int *slot)
743 int high = btrfs_header_nritems(eb);
745 const int key_size = sizeof(struct btrfs_disk_key);
748 btrfs_err(eb->fs_info,
749 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
750 __func__, low, high, eb->start,
751 btrfs_header_owner(eb), btrfs_header_level(eb));
757 unsigned long offset;
758 struct btrfs_disk_key *tmp;
759 struct btrfs_disk_key unaligned;
762 mid = (low + high) / 2;
763 offset = p + mid * item_size;
764 oip = offset_in_page(offset);
766 if (oip + key_size <= PAGE_SIZE) {
767 const unsigned long idx = get_eb_page_index(offset);
768 char *kaddr = page_address(eb->pages[idx]);
770 oip = get_eb_offset_in_page(eb, offset);
771 tmp = (struct btrfs_disk_key *)(kaddr + oip);
773 read_extent_buffer(eb, &unaligned, offset, key_size);
777 ret = comp_keys(tmp, key);
793 * simple bin_search frontend that does the right thing for
796 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
799 if (btrfs_header_level(eb) == 0)
800 return generic_bin_search(eb,
801 offsetof(struct btrfs_leaf, items),
802 sizeof(struct btrfs_item), key, slot);
804 return generic_bin_search(eb,
805 offsetof(struct btrfs_node, ptrs),
806 sizeof(struct btrfs_key_ptr), key, slot);
809 static void root_add_used(struct btrfs_root *root, u32 size)
811 spin_lock(&root->accounting_lock);
812 btrfs_set_root_used(&root->root_item,
813 btrfs_root_used(&root->root_item) + size);
814 spin_unlock(&root->accounting_lock);
817 static void root_sub_used(struct btrfs_root *root, u32 size)
819 spin_lock(&root->accounting_lock);
820 btrfs_set_root_used(&root->root_item,
821 btrfs_root_used(&root->root_item) - size);
822 spin_unlock(&root->accounting_lock);
825 /* given a node and slot number, this reads the blocks it points to. The
826 * extent buffer is returned with a reference taken (but unlocked).
828 struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
831 int level = btrfs_header_level(parent);
832 struct extent_buffer *eb;
833 struct btrfs_key first_key;
835 if (slot < 0 || slot >= btrfs_header_nritems(parent))
836 return ERR_PTR(-ENOENT);
840 btrfs_node_key_to_cpu(parent, &first_key, slot);
841 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
842 btrfs_header_owner(parent),
843 btrfs_node_ptr_generation(parent, slot),
844 level - 1, &first_key);
845 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
846 free_extent_buffer(eb);
854 * node level balancing, used to make sure nodes are in proper order for
855 * item deletion. We balance from the top down, so we have to make sure
856 * that a deletion won't leave an node completely empty later on.
858 static noinline int balance_level(struct btrfs_trans_handle *trans,
859 struct btrfs_root *root,
860 struct btrfs_path *path, int level)
862 struct btrfs_fs_info *fs_info = root->fs_info;
863 struct extent_buffer *right = NULL;
864 struct extent_buffer *mid;
865 struct extent_buffer *left = NULL;
866 struct extent_buffer *parent = NULL;
870 int orig_slot = path->slots[level];
875 mid = path->nodes[level];
877 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK);
878 WARN_ON(btrfs_header_generation(mid) != trans->transid);
880 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
882 if (level < BTRFS_MAX_LEVEL - 1) {
883 parent = path->nodes[level + 1];
884 pslot = path->slots[level + 1];
888 * deal with the case where there is only one pointer in the root
889 * by promoting the node below to a root
892 struct extent_buffer *child;
894 if (btrfs_header_nritems(mid) != 1)
897 /* promote the child to a root */
898 child = btrfs_read_node_slot(mid, 0);
900 ret = PTR_ERR(child);
901 btrfs_handle_fs_error(fs_info, ret, NULL);
905 btrfs_tree_lock(child);
906 ret = btrfs_cow_block(trans, root, child, mid, 0, &child,
909 btrfs_tree_unlock(child);
910 free_extent_buffer(child);
914 ret = btrfs_tree_mod_log_insert_root(root->node, child, true);
916 rcu_assign_pointer(root->node, child);
918 add_root_to_dirty_list(root);
919 btrfs_tree_unlock(child);
921 path->locks[level] = 0;
922 path->nodes[level] = NULL;
923 btrfs_clean_tree_block(mid);
924 btrfs_tree_unlock(mid);
925 /* once for the path */
926 free_extent_buffer(mid);
928 root_sub_used(root, mid->len);
929 btrfs_free_tree_block(trans, root, mid, 0, 1);
930 /* once for the root ptr */
931 free_extent_buffer_stale(mid);
934 if (btrfs_header_nritems(mid) >
935 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
938 left = btrfs_read_node_slot(parent, pslot - 1);
943 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
944 wret = btrfs_cow_block(trans, root, left,
945 parent, pslot - 1, &left,
946 BTRFS_NESTING_LEFT_COW);
953 right = btrfs_read_node_slot(parent, pslot + 1);
958 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
959 wret = btrfs_cow_block(trans, root, right,
960 parent, pslot + 1, &right,
961 BTRFS_NESTING_RIGHT_COW);
968 /* first, try to make some room in the middle buffer */
970 orig_slot += btrfs_header_nritems(left);
971 wret = push_node_left(trans, left, mid, 1);
977 * then try to empty the right most buffer into the middle
980 wret = push_node_left(trans, mid, right, 1);
981 if (wret < 0 && wret != -ENOSPC)
983 if (btrfs_header_nritems(right) == 0) {
984 btrfs_clean_tree_block(right);
985 btrfs_tree_unlock(right);
986 del_ptr(root, path, level + 1, pslot + 1);
987 root_sub_used(root, right->len);
988 btrfs_free_tree_block(trans, root, right, 0, 1);
989 free_extent_buffer_stale(right);
992 struct btrfs_disk_key right_key;
993 btrfs_node_key(right, &right_key, 0);
994 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
995 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
997 btrfs_set_node_key(parent, &right_key, pslot + 1);
998 btrfs_mark_buffer_dirty(parent);
1001 if (btrfs_header_nritems(mid) == 1) {
1003 * we're not allowed to leave a node with one item in the
1004 * tree during a delete. A deletion from lower in the tree
1005 * could try to delete the only pointer in this node.
1006 * So, pull some keys from the left.
1007 * There has to be a left pointer at this point because
1008 * otherwise we would have pulled some pointers from the
1013 btrfs_handle_fs_error(fs_info, ret, NULL);
1016 wret = balance_node_right(trans, mid, left);
1022 wret = push_node_left(trans, left, mid, 1);
1028 if (btrfs_header_nritems(mid) == 0) {
1029 btrfs_clean_tree_block(mid);
1030 btrfs_tree_unlock(mid);
1031 del_ptr(root, path, level + 1, pslot);
1032 root_sub_used(root, mid->len);
1033 btrfs_free_tree_block(trans, root, mid, 0, 1);
1034 free_extent_buffer_stale(mid);
1037 /* update the parent key to reflect our changes */
1038 struct btrfs_disk_key mid_key;
1039 btrfs_node_key(mid, &mid_key, 0);
1040 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1041 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1043 btrfs_set_node_key(parent, &mid_key, pslot);
1044 btrfs_mark_buffer_dirty(parent);
1047 /* update the path */
1049 if (btrfs_header_nritems(left) > orig_slot) {
1050 atomic_inc(&left->refs);
1051 /* left was locked after cow */
1052 path->nodes[level] = left;
1053 path->slots[level + 1] -= 1;
1054 path->slots[level] = orig_slot;
1056 btrfs_tree_unlock(mid);
1057 free_extent_buffer(mid);
1060 orig_slot -= btrfs_header_nritems(left);
1061 path->slots[level] = orig_slot;
1064 /* double check we haven't messed things up */
1066 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1070 btrfs_tree_unlock(right);
1071 free_extent_buffer(right);
1074 if (path->nodes[level] != left)
1075 btrfs_tree_unlock(left);
1076 free_extent_buffer(left);
1081 /* Node balancing for insertion. Here we only split or push nodes around
1082 * when they are completely full. This is also done top down, so we
1083 * have to be pessimistic.
1085 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1086 struct btrfs_root *root,
1087 struct btrfs_path *path, int level)
1089 struct btrfs_fs_info *fs_info = root->fs_info;
1090 struct extent_buffer *right = NULL;
1091 struct extent_buffer *mid;
1092 struct extent_buffer *left = NULL;
1093 struct extent_buffer *parent = NULL;
1097 int orig_slot = path->slots[level];
1102 mid = path->nodes[level];
1103 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1105 if (level < BTRFS_MAX_LEVEL - 1) {
1106 parent = path->nodes[level + 1];
1107 pslot = path->slots[level + 1];
1113 left = btrfs_read_node_slot(parent, pslot - 1);
1117 /* first, try to make some room in the middle buffer */
1121 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
1123 left_nr = btrfs_header_nritems(left);
1124 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1127 ret = btrfs_cow_block(trans, root, left, parent,
1129 BTRFS_NESTING_LEFT_COW);
1133 wret = push_node_left(trans, left, mid, 0);
1139 struct btrfs_disk_key disk_key;
1140 orig_slot += left_nr;
1141 btrfs_node_key(mid, &disk_key, 0);
1142 ret = btrfs_tree_mod_log_insert_key(parent, pslot,
1143 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1145 btrfs_set_node_key(parent, &disk_key, pslot);
1146 btrfs_mark_buffer_dirty(parent);
1147 if (btrfs_header_nritems(left) > orig_slot) {
1148 path->nodes[level] = left;
1149 path->slots[level + 1] -= 1;
1150 path->slots[level] = orig_slot;
1151 btrfs_tree_unlock(mid);
1152 free_extent_buffer(mid);
1155 btrfs_header_nritems(left);
1156 path->slots[level] = orig_slot;
1157 btrfs_tree_unlock(left);
1158 free_extent_buffer(left);
1162 btrfs_tree_unlock(left);
1163 free_extent_buffer(left);
1165 right = btrfs_read_node_slot(parent, pslot + 1);
1170 * then try to empty the right most buffer into the middle
1175 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
1177 right_nr = btrfs_header_nritems(right);
1178 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
1181 ret = btrfs_cow_block(trans, root, right,
1183 &right, BTRFS_NESTING_RIGHT_COW);
1187 wret = balance_node_right(trans, right, mid);
1193 struct btrfs_disk_key disk_key;
1195 btrfs_node_key(right, &disk_key, 0);
1196 ret = btrfs_tree_mod_log_insert_key(parent, pslot + 1,
1197 BTRFS_MOD_LOG_KEY_REPLACE, GFP_NOFS);
1199 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1200 btrfs_mark_buffer_dirty(parent);
1202 if (btrfs_header_nritems(mid) <= orig_slot) {
1203 path->nodes[level] = right;
1204 path->slots[level + 1] += 1;
1205 path->slots[level] = orig_slot -
1206 btrfs_header_nritems(mid);
1207 btrfs_tree_unlock(mid);
1208 free_extent_buffer(mid);
1210 btrfs_tree_unlock(right);
1211 free_extent_buffer(right);
1215 btrfs_tree_unlock(right);
1216 free_extent_buffer(right);
1222 * readahead one full node of leaves, finding things that are close
1223 * to the block in 'slot', and triggering ra on them.
1225 static void reada_for_search(struct btrfs_fs_info *fs_info,
1226 struct btrfs_path *path,
1227 int level, int slot, u64 objectid)
1229 struct extent_buffer *node;
1230 struct btrfs_disk_key disk_key;
1240 if (level != 1 && path->reada != READA_FORWARD_ALWAYS)
1243 if (!path->nodes[level])
1246 node = path->nodes[level];
1249 * Since the time between visiting leaves is much shorter than the time
1250 * between visiting nodes, limit read ahead of nodes to 1, to avoid too
1251 * much IO at once (possibly random).
1253 if (path->reada == READA_FORWARD_ALWAYS) {
1255 nread_max = node->fs_info->nodesize;
1257 nread_max = SZ_128K;
1262 search = btrfs_node_blockptr(node, slot);
1263 blocksize = fs_info->nodesize;
1264 if (path->reada != READA_FORWARD_ALWAYS) {
1265 struct extent_buffer *eb;
1267 eb = find_extent_buffer(fs_info, search);
1269 free_extent_buffer(eb);
1276 nritems = btrfs_header_nritems(node);
1280 if (path->reada == READA_BACK) {
1284 } else if (path->reada == READA_FORWARD ||
1285 path->reada == READA_FORWARD_ALWAYS) {
1290 if (path->reada == READA_BACK && objectid) {
1291 btrfs_node_key(node, &disk_key, nr);
1292 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1295 search = btrfs_node_blockptr(node, nr);
1296 if (path->reada == READA_FORWARD_ALWAYS ||
1297 (search <= target && target - search <= 65536) ||
1298 (search > target && search - target <= 65536)) {
1299 btrfs_readahead_node_child(node, nr);
1303 if (nread > nread_max || nscan > 32)
1308 static noinline void reada_for_balance(struct btrfs_path *path, int level)
1310 struct extent_buffer *parent;
1314 parent = path->nodes[level + 1];
1318 nritems = btrfs_header_nritems(parent);
1319 slot = path->slots[level + 1];
1322 btrfs_readahead_node_child(parent, slot - 1);
1323 if (slot + 1 < nritems)
1324 btrfs_readahead_node_child(parent, slot + 1);
1329 * when we walk down the tree, it is usually safe to unlock the higher layers
1330 * in the tree. The exceptions are when our path goes through slot 0, because
1331 * operations on the tree might require changing key pointers higher up in the
1334 * callers might also have set path->keep_locks, which tells this code to keep
1335 * the lock if the path points to the last slot in the block. This is part of
1336 * walking through the tree, and selecting the next slot in the higher block.
1338 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
1339 * if lowest_unlock is 1, level 0 won't be unlocked
1341 static noinline void unlock_up(struct btrfs_path *path, int level,
1342 int lowest_unlock, int min_write_lock_level,
1343 int *write_lock_level)
1346 int skip_level = level;
1348 struct extent_buffer *t;
1350 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1351 if (!path->nodes[i])
1353 if (!path->locks[i])
1355 if (!no_skips && path->slots[i] == 0) {
1359 if (!no_skips && path->keep_locks) {
1362 nritems = btrfs_header_nritems(t);
1363 if (nritems < 1 || path->slots[i] >= nritems - 1) {
1368 if (skip_level < i && i >= lowest_unlock)
1372 if (i >= lowest_unlock && i > skip_level) {
1373 btrfs_tree_unlock_rw(t, path->locks[i]);
1375 if (write_lock_level &&
1376 i > min_write_lock_level &&
1377 i <= *write_lock_level) {
1378 *write_lock_level = i - 1;
1385 * helper function for btrfs_search_slot. The goal is to find a block
1386 * in cache without setting the path to blocking. If we find the block
1387 * we return zero and the path is unchanged.
1389 * If we can't find the block, we set the path blocking and do some
1390 * reada. -EAGAIN is returned and the search must be repeated.
1393 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
1394 struct extent_buffer **eb_ret, int level, int slot,
1395 const struct btrfs_key *key)
1397 struct btrfs_fs_info *fs_info = root->fs_info;
1400 struct extent_buffer *tmp;
1401 struct btrfs_key first_key;
1405 blocknr = btrfs_node_blockptr(*eb_ret, slot);
1406 gen = btrfs_node_ptr_generation(*eb_ret, slot);
1407 parent_level = btrfs_header_level(*eb_ret);
1408 btrfs_node_key_to_cpu(*eb_ret, &first_key, slot);
1410 tmp = find_extent_buffer(fs_info, blocknr);
1412 if (p->reada == READA_FORWARD_ALWAYS)
1413 reada_for_search(fs_info, p, level, slot, key->objectid);
1415 /* first we do an atomic uptodate check */
1416 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
1418 * Do extra check for first_key, eb can be stale due to
1419 * being cached, read from scrub, or have multiple
1420 * parents (shared tree blocks).
1422 if (btrfs_verify_level_key(tmp,
1423 parent_level - 1, &first_key, gen)) {
1424 free_extent_buffer(tmp);
1431 /* now we're allowed to do a blocking uptodate check */
1432 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
1437 free_extent_buffer(tmp);
1438 btrfs_release_path(p);
1443 * reduce lock contention at high levels
1444 * of the btree by dropping locks before
1445 * we read. Don't release the lock on the current
1446 * level because we need to walk this node to figure
1447 * out which blocks to read.
1449 btrfs_unlock_up_safe(p, level + 1);
1451 if (p->reada != READA_NONE)
1452 reada_for_search(fs_info, p, level, slot, key->objectid);
1455 tmp = read_tree_block(fs_info, blocknr, root->root_key.objectid,
1456 gen, parent_level - 1, &first_key);
1459 * If the read above didn't mark this buffer up to date,
1460 * it will never end up being up to date. Set ret to EIO now
1461 * and give up so that our caller doesn't loop forever
1464 if (!extent_buffer_uptodate(tmp))
1466 free_extent_buffer(tmp);
1471 btrfs_release_path(p);
1476 * helper function for btrfs_search_slot. This does all of the checks
1477 * for node-level blocks and does any balancing required based on
1480 * If no extra work was required, zero is returned. If we had to
1481 * drop the path, -EAGAIN is returned and btrfs_search_slot must
1485 setup_nodes_for_search(struct btrfs_trans_handle *trans,
1486 struct btrfs_root *root, struct btrfs_path *p,
1487 struct extent_buffer *b, int level, int ins_len,
1488 int *write_lock_level)
1490 struct btrfs_fs_info *fs_info = root->fs_info;
1493 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
1494 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
1496 if (*write_lock_level < level + 1) {
1497 *write_lock_level = level + 1;
1498 btrfs_release_path(p);
1502 reada_for_balance(p, level);
1503 ret = split_node(trans, root, p, level);
1505 b = p->nodes[level];
1506 } else if (ins_len < 0 && btrfs_header_nritems(b) <
1507 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
1509 if (*write_lock_level < level + 1) {
1510 *write_lock_level = level + 1;
1511 btrfs_release_path(p);
1515 reada_for_balance(p, level);
1516 ret = balance_level(trans, root, p, level);
1520 b = p->nodes[level];
1522 btrfs_release_path(p);
1525 BUG_ON(btrfs_header_nritems(b) == 1);
1530 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
1531 u64 iobjectid, u64 ioff, u8 key_type,
1532 struct btrfs_key *found_key)
1535 struct btrfs_key key;
1536 struct extent_buffer *eb;
1541 key.type = key_type;
1542 key.objectid = iobjectid;
1545 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1549 eb = path->nodes[0];
1550 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
1551 ret = btrfs_next_leaf(fs_root, path);
1554 eb = path->nodes[0];
1557 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
1558 if (found_key->type != key.type ||
1559 found_key->objectid != key.objectid)
1565 static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
1566 struct btrfs_path *p,
1567 int write_lock_level)
1569 struct btrfs_fs_info *fs_info = root->fs_info;
1570 struct extent_buffer *b;
1574 /* We try very hard to do read locks on the root */
1575 root_lock = BTRFS_READ_LOCK;
1577 if (p->search_commit_root) {
1579 * The commit roots are read only so we always do read locks,
1580 * and we always must hold the commit_root_sem when doing
1581 * searches on them, the only exception is send where we don't
1582 * want to block transaction commits for a long time, so
1583 * we need to clone the commit root in order to avoid races
1584 * with transaction commits that create a snapshot of one of
1585 * the roots used by a send operation.
1587 if (p->need_commit_sem) {
1588 down_read(&fs_info->commit_root_sem);
1589 b = btrfs_clone_extent_buffer(root->commit_root);
1590 up_read(&fs_info->commit_root_sem);
1592 return ERR_PTR(-ENOMEM);
1595 b = root->commit_root;
1596 atomic_inc(&b->refs);
1598 level = btrfs_header_level(b);
1600 * Ensure that all callers have set skip_locking when
1601 * p->search_commit_root = 1.
1603 ASSERT(p->skip_locking == 1);
1608 if (p->skip_locking) {
1609 b = btrfs_root_node(root);
1610 level = btrfs_header_level(b);
1615 * If the level is set to maximum, we can skip trying to get the read
1618 if (write_lock_level < BTRFS_MAX_LEVEL) {
1620 * We don't know the level of the root node until we actually
1621 * have it read locked
1623 b = btrfs_read_lock_root_node(root);
1624 level = btrfs_header_level(b);
1625 if (level > write_lock_level)
1628 /* Whoops, must trade for write lock */
1629 btrfs_tree_read_unlock(b);
1630 free_extent_buffer(b);
1633 b = btrfs_lock_root_node(root);
1634 root_lock = BTRFS_WRITE_LOCK;
1636 /* The level might have changed, check again */
1637 level = btrfs_header_level(b);
1640 p->nodes[level] = b;
1641 if (!p->skip_locking)
1642 p->locks[level] = root_lock;
1644 * Callers are responsible for dropping b's references.
1651 * btrfs_search_slot - look for a key in a tree and perform necessary
1652 * modifications to preserve tree invariants.
1654 * @trans: Handle of transaction, used when modifying the tree
1655 * @p: Holds all btree nodes along the search path
1656 * @root: The root node of the tree
1657 * @key: The key we are looking for
1658 * @ins_len: Indicates purpose of search:
1659 * >0 for inserts it's size of item inserted (*)
1661 * 0 for plain searches, not modifying the tree
1663 * (*) If size of item inserted doesn't include
1664 * sizeof(struct btrfs_item), then p->search_for_extension must
1666 * @cow: boolean should CoW operations be performed. Must always be 1
1667 * when modifying the tree.
1669 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
1670 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
1672 * If @key is found, 0 is returned and you can find the item in the leaf level
1673 * of the path (level 0)
1675 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
1676 * points to the slot where it should be inserted
1678 * If an error is encountered while searching the tree a negative error number
1681 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1682 const struct btrfs_key *key, struct btrfs_path *p,
1683 int ins_len, int cow)
1685 struct extent_buffer *b;
1690 int lowest_unlock = 1;
1691 /* everything at write_lock_level or lower must be write locked */
1692 int write_lock_level = 0;
1693 u8 lowest_level = 0;
1694 int min_write_lock_level;
1697 lowest_level = p->lowest_level;
1698 WARN_ON(lowest_level && ins_len > 0);
1699 WARN_ON(p->nodes[0] != NULL);
1700 BUG_ON(!cow && ins_len);
1705 /* when we are removing items, we might have to go up to level
1706 * two as we update tree pointers Make sure we keep write
1707 * for those levels as well
1709 write_lock_level = 2;
1710 } else if (ins_len > 0) {
1712 * for inserting items, make sure we have a write lock on
1713 * level 1 so we can update keys
1715 write_lock_level = 1;
1719 write_lock_level = -1;
1721 if (cow && (p->keep_locks || p->lowest_level))
1722 write_lock_level = BTRFS_MAX_LEVEL;
1724 min_write_lock_level = write_lock_level;
1728 b = btrfs_search_slot_get_root(root, p, write_lock_level);
1737 level = btrfs_header_level(b);
1740 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
1743 * if we don't really need to cow this block
1744 * then we don't want to set the path blocking,
1745 * so we test it here
1747 if (!should_cow_block(trans, root, b))
1751 * must have write locks on this node and the
1754 if (level > write_lock_level ||
1755 (level + 1 > write_lock_level &&
1756 level + 1 < BTRFS_MAX_LEVEL &&
1757 p->nodes[level + 1])) {
1758 write_lock_level = level + 1;
1759 btrfs_release_path(p);
1764 err = btrfs_cow_block(trans, root, b, NULL, 0,
1768 err = btrfs_cow_block(trans, root, b,
1769 p->nodes[level + 1],
1770 p->slots[level + 1], &b,
1778 p->nodes[level] = b;
1780 * Leave path with blocking locks to avoid massive
1781 * lock context switch, this is made on purpose.
1785 * we have a lock on b and as long as we aren't changing
1786 * the tree, there is no way to for the items in b to change.
1787 * It is safe to drop the lock on our parent before we
1788 * go through the expensive btree search on b.
1790 * If we're inserting or deleting (ins_len != 0), then we might
1791 * be changing slot zero, which may require changing the parent.
1792 * So, we can't drop the lock until after we know which slot
1793 * we're operating on.
1795 if (!ins_len && !p->keep_locks) {
1798 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
1799 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
1805 * If btrfs_bin_search returns an exact match (prev_cmp == 0)
1806 * we can safely assume the target key will always be in slot 0
1807 * on lower levels due to the invariants BTRFS' btree provides,
1808 * namely that a btrfs_key_ptr entry always points to the
1809 * lowest key in the child node, thus we can skip searching
1812 if (prev_cmp == 0) {
1816 ret = btrfs_bin_search(b, key, &slot);
1823 p->slots[level] = slot;
1825 * Item key already exists. In this case, if we are
1826 * allowed to insert the item (for example, in dir_item
1827 * case, item key collision is allowed), it will be
1828 * merged with the original item. Only the item size
1829 * grows, no new btrfs item will be added. If
1830 * search_for_extension is not set, ins_len already
1831 * accounts the size btrfs_item, deduct it here so leaf
1832 * space check will be correct.
1834 if (ret == 0 && ins_len > 0 && !p->search_for_extension) {
1835 ASSERT(ins_len >= sizeof(struct btrfs_item));
1836 ins_len -= sizeof(struct btrfs_item);
1839 btrfs_leaf_free_space(b) < ins_len) {
1840 if (write_lock_level < 1) {
1841 write_lock_level = 1;
1842 btrfs_release_path(p);
1846 err = split_leaf(trans, root, key,
1847 p, ins_len, ret == 0);
1855 if (!p->search_for_split)
1856 unlock_up(p, level, lowest_unlock,
1857 min_write_lock_level, NULL);
1860 if (ret && slot > 0) {
1864 p->slots[level] = slot;
1865 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
1873 b = p->nodes[level];
1874 slot = p->slots[level];
1877 * Slot 0 is special, if we change the key we have to update
1878 * the parent pointer which means we must have a write lock on
1881 if (slot == 0 && ins_len && write_lock_level < level + 1) {
1882 write_lock_level = level + 1;
1883 btrfs_release_path(p);
1887 unlock_up(p, level, lowest_unlock, min_write_lock_level,
1890 if (level == lowest_level) {
1896 err = read_block_for_search(root, p, &b, level, slot, key);
1904 if (!p->skip_locking) {
1905 level = btrfs_header_level(b);
1906 if (level <= write_lock_level) {
1908 p->locks[level] = BTRFS_WRITE_LOCK;
1910 btrfs_tree_read_lock(b);
1911 p->locks[level] = BTRFS_READ_LOCK;
1913 p->nodes[level] = b;
1918 if (ret < 0 && !p->skip_release_on_error)
1919 btrfs_release_path(p);
1922 ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO);
1925 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
1926 * current state of the tree together with the operations recorded in the tree
1927 * modification log to search for the key in a previous version of this tree, as
1928 * denoted by the time_seq parameter.
1930 * Naturally, there is no support for insert, delete or cow operations.
1932 * The resulting path and return value will be set up as if we called
1933 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
1935 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
1936 struct btrfs_path *p, u64 time_seq)
1938 struct btrfs_fs_info *fs_info = root->fs_info;
1939 struct extent_buffer *b;
1944 int lowest_unlock = 1;
1945 u8 lowest_level = 0;
1947 lowest_level = p->lowest_level;
1948 WARN_ON(p->nodes[0] != NULL);
1950 if (p->search_commit_root) {
1952 return btrfs_search_slot(NULL, root, key, p, 0, 0);
1956 b = btrfs_get_old_root(root, time_seq);
1961 level = btrfs_header_level(b);
1962 p->locks[level] = BTRFS_READ_LOCK;
1967 level = btrfs_header_level(b);
1968 p->nodes[level] = b;
1971 * we have a lock on b and as long as we aren't changing
1972 * the tree, there is no way to for the items in b to change.
1973 * It is safe to drop the lock on our parent before we
1974 * go through the expensive btree search on b.
1976 btrfs_unlock_up_safe(p, level + 1);
1978 ret = btrfs_bin_search(b, key, &slot);
1983 p->slots[level] = slot;
1984 unlock_up(p, level, lowest_unlock, 0, NULL);
1988 if (ret && slot > 0) {
1992 p->slots[level] = slot;
1993 unlock_up(p, level, lowest_unlock, 0, NULL);
1995 if (level == lowest_level) {
2001 err = read_block_for_search(root, p, &b, level, slot, key);
2009 level = btrfs_header_level(b);
2010 btrfs_tree_read_lock(b);
2011 b = btrfs_tree_mod_log_rewind(fs_info, p, b, time_seq);
2016 p->locks[level] = BTRFS_READ_LOCK;
2017 p->nodes[level] = b;
2022 btrfs_release_path(p);
2028 * helper to use instead of search slot if no exact match is needed but
2029 * instead the next or previous item should be returned.
2030 * When find_higher is true, the next higher item is returned, the next lower
2032 * When return_any and find_higher are both true, and no higher item is found,
2033 * return the next lower instead.
2034 * When return_any is true and find_higher is false, and no lower item is found,
2035 * return the next higher instead.
2036 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2039 int btrfs_search_slot_for_read(struct btrfs_root *root,
2040 const struct btrfs_key *key,
2041 struct btrfs_path *p, int find_higher,
2045 struct extent_buffer *leaf;
2048 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2052 * a return value of 1 means the path is at the position where the
2053 * item should be inserted. Normally this is the next bigger item,
2054 * but in case the previous item is the last in a leaf, path points
2055 * to the first free slot in the previous leaf, i.e. at an invalid
2061 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2062 ret = btrfs_next_leaf(root, p);
2068 * no higher item found, return the next
2073 btrfs_release_path(p);
2077 if (p->slots[0] == 0) {
2078 ret = btrfs_prev_leaf(root, p);
2083 if (p->slots[0] == btrfs_header_nritems(leaf))
2090 * no lower item found, return the next
2095 btrfs_release_path(p);
2105 * Execute search and call btrfs_previous_item to traverse backwards if the item
2108 * Return 0 if found, 1 if not found and < 0 if error.
2110 int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,
2111 struct btrfs_path *path)
2115 ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
2117 ret = btrfs_previous_item(root, path, key->objectid, key->type);
2120 btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);
2126 * adjust the pointers going up the tree, starting at level
2127 * making sure the right key of each node is points to 'key'.
2128 * This is used after shifting pointers to the left, so it stops
2129 * fixing up pointers when a given leaf/node is not in slot 0 of the
2133 static void fixup_low_keys(struct btrfs_path *path,
2134 struct btrfs_disk_key *key, int level)
2137 struct extent_buffer *t;
2140 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2141 int tslot = path->slots[i];
2143 if (!path->nodes[i])
2146 ret = btrfs_tree_mod_log_insert_key(t, tslot,
2147 BTRFS_MOD_LOG_KEY_REPLACE, GFP_ATOMIC);
2149 btrfs_set_node_key(t, key, tslot);
2150 btrfs_mark_buffer_dirty(path->nodes[i]);
2159 * This function isn't completely safe. It's the caller's responsibility
2160 * that the new key won't break the order
2162 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
2163 struct btrfs_path *path,
2164 const struct btrfs_key *new_key)
2166 struct btrfs_disk_key disk_key;
2167 struct extent_buffer *eb;
2170 eb = path->nodes[0];
2171 slot = path->slots[0];
2173 btrfs_item_key(eb, &disk_key, slot - 1);
2174 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
2176 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2177 slot, btrfs_disk_key_objectid(&disk_key),
2178 btrfs_disk_key_type(&disk_key),
2179 btrfs_disk_key_offset(&disk_key),
2180 new_key->objectid, new_key->type,
2182 btrfs_print_leaf(eb);
2186 if (slot < btrfs_header_nritems(eb) - 1) {
2187 btrfs_item_key(eb, &disk_key, slot + 1);
2188 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
2190 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
2191 slot, btrfs_disk_key_objectid(&disk_key),
2192 btrfs_disk_key_type(&disk_key),
2193 btrfs_disk_key_offset(&disk_key),
2194 new_key->objectid, new_key->type,
2196 btrfs_print_leaf(eb);
2201 btrfs_cpu_key_to_disk(&disk_key, new_key);
2202 btrfs_set_item_key(eb, &disk_key, slot);
2203 btrfs_mark_buffer_dirty(eb);
2205 fixup_low_keys(path, &disk_key, 1);
2209 * Check key order of two sibling extent buffers.
2211 * Return true if something is wrong.
2212 * Return false if everything is fine.
2214 * Tree-checker only works inside one tree block, thus the following
2215 * corruption can not be detected by tree-checker:
2217 * Leaf @left | Leaf @right
2218 * --------------------------------------------------------------
2219 * | 1 | 2 | 3 | 4 | 5 | f6 | | 7 | 8 |
2221 * Key f6 in leaf @left itself is valid, but not valid when the next
2222 * key in leaf @right is 7.
2223 * This can only be checked at tree block merge time.
2224 * And since tree checker has ensured all key order in each tree block
2225 * is correct, we only need to bother the last key of @left and the first
2228 static bool check_sibling_keys(struct extent_buffer *left,
2229 struct extent_buffer *right)
2231 struct btrfs_key left_last;
2232 struct btrfs_key right_first;
2233 int level = btrfs_header_level(left);
2234 int nr_left = btrfs_header_nritems(left);
2235 int nr_right = btrfs_header_nritems(right);
2237 /* No key to check in one of the tree blocks */
2238 if (!nr_left || !nr_right)
2242 btrfs_node_key_to_cpu(left, &left_last, nr_left - 1);
2243 btrfs_node_key_to_cpu(right, &right_first, 0);
2245 btrfs_item_key_to_cpu(left, &left_last, nr_left - 1);
2246 btrfs_item_key_to_cpu(right, &right_first, 0);
2249 if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
2250 btrfs_crit(left->fs_info,
2251 "bad key order, sibling blocks, left last (%llu %u %llu) right first (%llu %u %llu)",
2252 left_last.objectid, left_last.type,
2253 left_last.offset, right_first.objectid,
2254 right_first.type, right_first.offset);
2261 * try to push data from one node into the next node left in the
2264 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2265 * error, and > 0 if there was no room in the left hand block.
2267 static int push_node_left(struct btrfs_trans_handle *trans,
2268 struct extent_buffer *dst,
2269 struct extent_buffer *src, int empty)
2271 struct btrfs_fs_info *fs_info = trans->fs_info;
2277 src_nritems = btrfs_header_nritems(src);
2278 dst_nritems = btrfs_header_nritems(dst);
2279 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2280 WARN_ON(btrfs_header_generation(src) != trans->transid);
2281 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2283 if (!empty && src_nritems <= 8)
2286 if (push_items <= 0)
2290 push_items = min(src_nritems, push_items);
2291 if (push_items < src_nritems) {
2292 /* leave at least 8 pointers in the node if
2293 * we aren't going to empty it
2295 if (src_nritems - push_items < 8) {
2296 if (push_items <= 8)
2302 push_items = min(src_nritems - 8, push_items);
2304 /* dst is the left eb, src is the middle eb */
2305 if (check_sibling_keys(dst, src)) {
2307 btrfs_abort_transaction(trans, ret);
2310 ret = btrfs_tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
2312 btrfs_abort_transaction(trans, ret);
2315 copy_extent_buffer(dst, src,
2316 btrfs_node_key_ptr_offset(dst_nritems),
2317 btrfs_node_key_ptr_offset(0),
2318 push_items * sizeof(struct btrfs_key_ptr));
2320 if (push_items < src_nritems) {
2322 * Don't call btrfs_tree_mod_log_insert_move() here, key removal
2323 * was already fully logged by btrfs_tree_mod_log_eb_copy() above.
2325 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
2326 btrfs_node_key_ptr_offset(push_items),
2327 (src_nritems - push_items) *
2328 sizeof(struct btrfs_key_ptr));
2330 btrfs_set_header_nritems(src, src_nritems - push_items);
2331 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2332 btrfs_mark_buffer_dirty(src);
2333 btrfs_mark_buffer_dirty(dst);
2339 * try to push data from one node into the next node right in the
2342 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
2343 * error, and > 0 if there was no room in the right hand block.
2345 * this will only push up to 1/2 the contents of the left node over
2347 static int balance_node_right(struct btrfs_trans_handle *trans,
2348 struct extent_buffer *dst,
2349 struct extent_buffer *src)
2351 struct btrfs_fs_info *fs_info = trans->fs_info;
2358 WARN_ON(btrfs_header_generation(src) != trans->transid);
2359 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2361 src_nritems = btrfs_header_nritems(src);
2362 dst_nritems = btrfs_header_nritems(dst);
2363 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
2364 if (push_items <= 0)
2367 if (src_nritems < 4)
2370 max_push = src_nritems / 2 + 1;
2371 /* don't try to empty the node */
2372 if (max_push >= src_nritems)
2375 if (max_push < push_items)
2376 push_items = max_push;
2378 /* dst is the right eb, src is the middle eb */
2379 if (check_sibling_keys(src, dst)) {
2381 btrfs_abort_transaction(trans, ret);
2384 ret = btrfs_tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
2386 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
2387 btrfs_node_key_ptr_offset(0),
2389 sizeof(struct btrfs_key_ptr));
2391 ret = btrfs_tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
2394 btrfs_abort_transaction(trans, ret);
2397 copy_extent_buffer(dst, src,
2398 btrfs_node_key_ptr_offset(0),
2399 btrfs_node_key_ptr_offset(src_nritems - push_items),
2400 push_items * sizeof(struct btrfs_key_ptr));
2402 btrfs_set_header_nritems(src, src_nritems - push_items);
2403 btrfs_set_header_nritems(dst, dst_nritems + push_items);
2405 btrfs_mark_buffer_dirty(src);
2406 btrfs_mark_buffer_dirty(dst);
2412 * helper function to insert a new root level in the tree.
2413 * A new node is allocated, and a single item is inserted to
2414 * point to the existing root
2416 * returns zero on success or < 0 on failure.
2418 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
2419 struct btrfs_root *root,
2420 struct btrfs_path *path, int level)
2422 struct btrfs_fs_info *fs_info = root->fs_info;
2424 struct extent_buffer *lower;
2425 struct extent_buffer *c;
2426 struct extent_buffer *old;
2427 struct btrfs_disk_key lower_key;
2430 BUG_ON(path->nodes[level]);
2431 BUG_ON(path->nodes[level-1] != root->node);
2433 lower = path->nodes[level-1];
2435 btrfs_item_key(lower, &lower_key, 0);
2437 btrfs_node_key(lower, &lower_key, 0);
2439 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2440 &lower_key, level, root->node->start, 0,
2441 BTRFS_NESTING_NEW_ROOT);
2445 root_add_used(root, fs_info->nodesize);
2447 btrfs_set_header_nritems(c, 1);
2448 btrfs_set_node_key(c, &lower_key, 0);
2449 btrfs_set_node_blockptr(c, 0, lower->start);
2450 lower_gen = btrfs_header_generation(lower);
2451 WARN_ON(lower_gen != trans->transid);
2453 btrfs_set_node_ptr_generation(c, 0, lower_gen);
2455 btrfs_mark_buffer_dirty(c);
2458 ret = btrfs_tree_mod_log_insert_root(root->node, c, false);
2460 rcu_assign_pointer(root->node, c);
2462 /* the super has an extra ref to root->node */
2463 free_extent_buffer(old);
2465 add_root_to_dirty_list(root);
2466 atomic_inc(&c->refs);
2467 path->nodes[level] = c;
2468 path->locks[level] = BTRFS_WRITE_LOCK;
2469 path->slots[level] = 0;
2474 * worker function to insert a single pointer in a node.
2475 * the node should have enough room for the pointer already
2477 * slot and level indicate where you want the key to go, and
2478 * blocknr is the block the key points to.
2480 static void insert_ptr(struct btrfs_trans_handle *trans,
2481 struct btrfs_path *path,
2482 struct btrfs_disk_key *key, u64 bytenr,
2483 int slot, int level)
2485 struct extent_buffer *lower;
2489 BUG_ON(!path->nodes[level]);
2490 btrfs_assert_tree_locked(path->nodes[level]);
2491 lower = path->nodes[level];
2492 nritems = btrfs_header_nritems(lower);
2493 BUG_ON(slot > nritems);
2494 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
2495 if (slot != nritems) {
2497 ret = btrfs_tree_mod_log_insert_move(lower, slot + 1,
2498 slot, nritems - slot);
2501 memmove_extent_buffer(lower,
2502 btrfs_node_key_ptr_offset(slot + 1),
2503 btrfs_node_key_ptr_offset(slot),
2504 (nritems - slot) * sizeof(struct btrfs_key_ptr));
2507 ret = btrfs_tree_mod_log_insert_key(lower, slot,
2508 BTRFS_MOD_LOG_KEY_ADD, GFP_NOFS);
2511 btrfs_set_node_key(lower, key, slot);
2512 btrfs_set_node_blockptr(lower, slot, bytenr);
2513 WARN_ON(trans->transid == 0);
2514 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
2515 btrfs_set_header_nritems(lower, nritems + 1);
2516 btrfs_mark_buffer_dirty(lower);
2520 * split the node at the specified level in path in two.
2521 * The path is corrected to point to the appropriate node after the split
2523 * Before splitting this tries to make some room in the node by pushing
2524 * left and right, if either one works, it returns right away.
2526 * returns 0 on success and < 0 on failure
2528 static noinline int split_node(struct btrfs_trans_handle *trans,
2529 struct btrfs_root *root,
2530 struct btrfs_path *path, int level)
2532 struct btrfs_fs_info *fs_info = root->fs_info;
2533 struct extent_buffer *c;
2534 struct extent_buffer *split;
2535 struct btrfs_disk_key disk_key;
2540 c = path->nodes[level];
2541 WARN_ON(btrfs_header_generation(c) != trans->transid);
2542 if (c == root->node) {
2544 * trying to split the root, lets make a new one
2546 * tree mod log: We don't log_removal old root in
2547 * insert_new_root, because that root buffer will be kept as a
2548 * normal node. We are going to log removal of half of the
2549 * elements below with btrfs_tree_mod_log_eb_copy(). We're
2550 * holding a tree lock on the buffer, which is why we cannot
2551 * race with other tree_mod_log users.
2553 ret = insert_new_root(trans, root, path, level + 1);
2557 ret = push_nodes_for_insert(trans, root, path, level);
2558 c = path->nodes[level];
2559 if (!ret && btrfs_header_nritems(c) <
2560 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
2566 c_nritems = btrfs_header_nritems(c);
2567 mid = (c_nritems + 1) / 2;
2568 btrfs_node_key(c, &disk_key, mid);
2570 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
2571 &disk_key, level, c->start, 0,
2572 BTRFS_NESTING_SPLIT);
2574 return PTR_ERR(split);
2576 root_add_used(root, fs_info->nodesize);
2577 ASSERT(btrfs_header_level(c) == level);
2579 ret = btrfs_tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
2581 btrfs_abort_transaction(trans, ret);
2584 copy_extent_buffer(split, c,
2585 btrfs_node_key_ptr_offset(0),
2586 btrfs_node_key_ptr_offset(mid),
2587 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
2588 btrfs_set_header_nritems(split, c_nritems - mid);
2589 btrfs_set_header_nritems(c, mid);
2591 btrfs_mark_buffer_dirty(c);
2592 btrfs_mark_buffer_dirty(split);
2594 insert_ptr(trans, path, &disk_key, split->start,
2595 path->slots[level + 1] + 1, level + 1);
2597 if (path->slots[level] >= mid) {
2598 path->slots[level] -= mid;
2599 btrfs_tree_unlock(c);
2600 free_extent_buffer(c);
2601 path->nodes[level] = split;
2602 path->slots[level + 1] += 1;
2604 btrfs_tree_unlock(split);
2605 free_extent_buffer(split);
2611 * how many bytes are required to store the items in a leaf. start
2612 * and nr indicate which items in the leaf to check. This totals up the
2613 * space used both by the item structs and the item data
2615 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
2617 struct btrfs_item *start_item;
2618 struct btrfs_item *end_item;
2620 int nritems = btrfs_header_nritems(l);
2621 int end = min(nritems, start + nr) - 1;
2625 start_item = btrfs_item_nr(start);
2626 end_item = btrfs_item_nr(end);
2627 data_len = btrfs_item_offset(l, start_item) +
2628 btrfs_item_size(l, start_item);
2629 data_len = data_len - btrfs_item_offset(l, end_item);
2630 data_len += sizeof(struct btrfs_item) * nr;
2631 WARN_ON(data_len < 0);
2636 * The space between the end of the leaf items and
2637 * the start of the leaf data. IOW, how much room
2638 * the leaf has left for both items and data
2640 noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
2642 struct btrfs_fs_info *fs_info = leaf->fs_info;
2643 int nritems = btrfs_header_nritems(leaf);
2646 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
2649 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
2651 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
2652 leaf_space_used(leaf, 0, nritems), nritems);
2658 * min slot controls the lowest index we're willing to push to the
2659 * right. We'll push up to and including min_slot, but no lower
2661 static noinline int __push_leaf_right(struct btrfs_path *path,
2662 int data_size, int empty,
2663 struct extent_buffer *right,
2664 int free_space, u32 left_nritems,
2667 struct btrfs_fs_info *fs_info = right->fs_info;
2668 struct extent_buffer *left = path->nodes[0];
2669 struct extent_buffer *upper = path->nodes[1];
2670 struct btrfs_map_token token;
2671 struct btrfs_disk_key disk_key;
2676 struct btrfs_item *item;
2685 nr = max_t(u32, 1, min_slot);
2687 if (path->slots[0] >= left_nritems)
2688 push_space += data_size;
2690 slot = path->slots[1];
2691 i = left_nritems - 1;
2693 item = btrfs_item_nr(i);
2695 if (!empty && push_items > 0) {
2696 if (path->slots[0] > i)
2698 if (path->slots[0] == i) {
2699 int space = btrfs_leaf_free_space(left);
2701 if (space + push_space * 2 > free_space)
2706 if (path->slots[0] == i)
2707 push_space += data_size;
2709 this_item_size = btrfs_item_size(left, item);
2710 if (this_item_size + sizeof(*item) + push_space > free_space)
2714 push_space += this_item_size + sizeof(*item);
2720 if (push_items == 0)
2723 WARN_ON(!empty && push_items == left_nritems);
2725 /* push left to right */
2726 right_nritems = btrfs_header_nritems(right);
2728 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
2729 push_space -= leaf_data_end(left);
2731 /* make room in the right data area */
2732 data_end = leaf_data_end(right);
2733 memmove_extent_buffer(right,
2734 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
2735 BTRFS_LEAF_DATA_OFFSET + data_end,
2736 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
2738 /* copy from the left data area */
2739 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
2740 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
2741 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
2744 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
2745 btrfs_item_nr_offset(0),
2746 right_nritems * sizeof(struct btrfs_item));
2748 /* copy the items from left to right */
2749 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
2750 btrfs_item_nr_offset(left_nritems - push_items),
2751 push_items * sizeof(struct btrfs_item));
2753 /* update the item pointers */
2754 btrfs_init_map_token(&token, right);
2755 right_nritems += push_items;
2756 btrfs_set_header_nritems(right, right_nritems);
2757 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
2758 for (i = 0; i < right_nritems; i++) {
2759 item = btrfs_item_nr(i);
2760 push_space -= btrfs_token_item_size(&token, item);
2761 btrfs_set_token_item_offset(&token, item, push_space);
2764 left_nritems -= push_items;
2765 btrfs_set_header_nritems(left, left_nritems);
2768 btrfs_mark_buffer_dirty(left);
2770 btrfs_clean_tree_block(left);
2772 btrfs_mark_buffer_dirty(right);
2774 btrfs_item_key(right, &disk_key, 0);
2775 btrfs_set_node_key(upper, &disk_key, slot + 1);
2776 btrfs_mark_buffer_dirty(upper);
2778 /* then fixup the leaf pointer in the path */
2779 if (path->slots[0] >= left_nritems) {
2780 path->slots[0] -= left_nritems;
2781 if (btrfs_header_nritems(path->nodes[0]) == 0)
2782 btrfs_clean_tree_block(path->nodes[0]);
2783 btrfs_tree_unlock(path->nodes[0]);
2784 free_extent_buffer(path->nodes[0]);
2785 path->nodes[0] = right;
2786 path->slots[1] += 1;
2788 btrfs_tree_unlock(right);
2789 free_extent_buffer(right);
2794 btrfs_tree_unlock(right);
2795 free_extent_buffer(right);
2800 * push some data in the path leaf to the right, trying to free up at
2801 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2803 * returns 1 if the push failed because the other node didn't have enough
2804 * room, 0 if everything worked out and < 0 if there were major errors.
2806 * this will push starting from min_slot to the end of the leaf. It won't
2807 * push any slot lower than min_slot
2809 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
2810 *root, struct btrfs_path *path,
2811 int min_data_size, int data_size,
2812 int empty, u32 min_slot)
2814 struct extent_buffer *left = path->nodes[0];
2815 struct extent_buffer *right;
2816 struct extent_buffer *upper;
2822 if (!path->nodes[1])
2825 slot = path->slots[1];
2826 upper = path->nodes[1];
2827 if (slot >= btrfs_header_nritems(upper) - 1)
2830 btrfs_assert_tree_locked(path->nodes[1]);
2832 right = btrfs_read_node_slot(upper, slot + 1);
2834 * slot + 1 is not valid or we fail to read the right node,
2835 * no big deal, just return.
2840 __btrfs_tree_lock(right, BTRFS_NESTING_RIGHT);
2842 free_space = btrfs_leaf_free_space(right);
2843 if (free_space < data_size)
2846 /* cow and double check */
2847 ret = btrfs_cow_block(trans, root, right, upper,
2848 slot + 1, &right, BTRFS_NESTING_RIGHT_COW);
2852 free_space = btrfs_leaf_free_space(right);
2853 if (free_space < data_size)
2856 left_nritems = btrfs_header_nritems(left);
2857 if (left_nritems == 0)
2860 if (check_sibling_keys(left, right)) {
2862 btrfs_tree_unlock(right);
2863 free_extent_buffer(right);
2866 if (path->slots[0] == left_nritems && !empty) {
2867 /* Key greater than all keys in the leaf, right neighbor has
2868 * enough room for it and we're not emptying our leaf to delete
2869 * it, therefore use right neighbor to insert the new item and
2870 * no need to touch/dirty our left leaf. */
2871 btrfs_tree_unlock(left);
2872 free_extent_buffer(left);
2873 path->nodes[0] = right;
2879 return __push_leaf_right(path, min_data_size, empty,
2880 right, free_space, left_nritems, min_slot);
2882 btrfs_tree_unlock(right);
2883 free_extent_buffer(right);
2888 * push some data in the path leaf to the left, trying to free up at
2889 * least data_size bytes. returns zero if the push worked, nonzero otherwise
2891 * max_slot can put a limit on how far into the leaf we'll push items. The
2892 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
2895 static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
2896 int empty, struct extent_buffer *left,
2897 int free_space, u32 right_nritems,
2900 struct btrfs_fs_info *fs_info = left->fs_info;
2901 struct btrfs_disk_key disk_key;
2902 struct extent_buffer *right = path->nodes[0];
2906 struct btrfs_item *item;
2907 u32 old_left_nritems;
2911 u32 old_left_item_size;
2912 struct btrfs_map_token token;
2915 nr = min(right_nritems, max_slot);
2917 nr = min(right_nritems - 1, max_slot);
2919 for (i = 0; i < nr; i++) {
2920 item = btrfs_item_nr(i);
2922 if (!empty && push_items > 0) {
2923 if (path->slots[0] < i)
2925 if (path->slots[0] == i) {
2926 int space = btrfs_leaf_free_space(right);
2928 if (space + push_space * 2 > free_space)
2933 if (path->slots[0] == i)
2934 push_space += data_size;
2936 this_item_size = btrfs_item_size(right, item);
2937 if (this_item_size + sizeof(*item) + push_space > free_space)
2941 push_space += this_item_size + sizeof(*item);
2944 if (push_items == 0) {
2948 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
2950 /* push data from right to left */
2951 copy_extent_buffer(left, right,
2952 btrfs_item_nr_offset(btrfs_header_nritems(left)),
2953 btrfs_item_nr_offset(0),
2954 push_items * sizeof(struct btrfs_item));
2956 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
2957 btrfs_item_offset_nr(right, push_items - 1);
2959 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
2960 leaf_data_end(left) - push_space,
2961 BTRFS_LEAF_DATA_OFFSET +
2962 btrfs_item_offset_nr(right, push_items - 1),
2964 old_left_nritems = btrfs_header_nritems(left);
2965 BUG_ON(old_left_nritems <= 0);
2967 btrfs_init_map_token(&token, left);
2968 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
2969 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
2972 item = btrfs_item_nr(i);
2974 ioff = btrfs_token_item_offset(&token, item);
2975 btrfs_set_token_item_offset(&token, item,
2976 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size));
2978 btrfs_set_header_nritems(left, old_left_nritems + push_items);
2980 /* fixup right node */
2981 if (push_items > right_nritems)
2982 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
2985 if (push_items < right_nritems) {
2986 push_space = btrfs_item_offset_nr(right, push_items - 1) -
2987 leaf_data_end(right);
2988 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
2989 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
2990 BTRFS_LEAF_DATA_OFFSET +
2991 leaf_data_end(right), push_space);
2993 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
2994 btrfs_item_nr_offset(push_items),
2995 (btrfs_header_nritems(right) - push_items) *
2996 sizeof(struct btrfs_item));
2999 btrfs_init_map_token(&token, right);
3000 right_nritems -= push_items;
3001 btrfs_set_header_nritems(right, right_nritems);
3002 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3003 for (i = 0; i < right_nritems; i++) {
3004 item = btrfs_item_nr(i);
3006 push_space = push_space - btrfs_token_item_size(&token, item);
3007 btrfs_set_token_item_offset(&token, item, push_space);
3010 btrfs_mark_buffer_dirty(left);
3012 btrfs_mark_buffer_dirty(right);
3014 btrfs_clean_tree_block(right);
3016 btrfs_item_key(right, &disk_key, 0);
3017 fixup_low_keys(path, &disk_key, 1);
3019 /* then fixup the leaf pointer in the path */
3020 if (path->slots[0] < push_items) {
3021 path->slots[0] += old_left_nritems;
3022 btrfs_tree_unlock(path->nodes[0]);
3023 free_extent_buffer(path->nodes[0]);
3024 path->nodes[0] = left;
3025 path->slots[1] -= 1;
3027 btrfs_tree_unlock(left);
3028 free_extent_buffer(left);
3029 path->slots[0] -= push_items;
3031 BUG_ON(path->slots[0] < 0);
3034 btrfs_tree_unlock(left);
3035 free_extent_buffer(left);
3040 * push some data in the path leaf to the left, trying to free up at
3041 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3043 * max_slot can put a limit on how far into the leaf we'll push items. The
3044 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3047 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3048 *root, struct btrfs_path *path, int min_data_size,
3049 int data_size, int empty, u32 max_slot)
3051 struct extent_buffer *right = path->nodes[0];
3052 struct extent_buffer *left;
3058 slot = path->slots[1];
3061 if (!path->nodes[1])
3064 right_nritems = btrfs_header_nritems(right);
3065 if (right_nritems == 0)
3068 btrfs_assert_tree_locked(path->nodes[1]);
3070 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
3072 * slot - 1 is not valid or we fail to read the left node,
3073 * no big deal, just return.
3078 __btrfs_tree_lock(left, BTRFS_NESTING_LEFT);
3080 free_space = btrfs_leaf_free_space(left);
3081 if (free_space < data_size) {
3086 /* cow and double check */
3087 ret = btrfs_cow_block(trans, root, left,
3088 path->nodes[1], slot - 1, &left,
3089 BTRFS_NESTING_LEFT_COW);
3091 /* we hit -ENOSPC, but it isn't fatal here */
3097 free_space = btrfs_leaf_free_space(left);
3098 if (free_space < data_size) {
3103 if (check_sibling_keys(left, right)) {
3107 return __push_leaf_left(path, min_data_size,
3108 empty, left, free_space, right_nritems,
3111 btrfs_tree_unlock(left);
3112 free_extent_buffer(left);
3117 * split the path's leaf in two, making sure there is at least data_size
3118 * available for the resulting leaf level of the path.
3120 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3121 struct btrfs_path *path,
3122 struct extent_buffer *l,
3123 struct extent_buffer *right,
3124 int slot, int mid, int nritems)
3126 struct btrfs_fs_info *fs_info = trans->fs_info;
3130 struct btrfs_disk_key disk_key;
3131 struct btrfs_map_token token;
3133 nritems = nritems - mid;
3134 btrfs_set_header_nritems(right, nritems);
3135 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
3137 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3138 btrfs_item_nr_offset(mid),
3139 nritems * sizeof(struct btrfs_item));
3141 copy_extent_buffer(right, l,
3142 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
3143 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
3144 leaf_data_end(l), data_copy_size);
3146 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
3148 btrfs_init_map_token(&token, right);
3149 for (i = 0; i < nritems; i++) {
3150 struct btrfs_item *item = btrfs_item_nr(i);
3153 ioff = btrfs_token_item_offset(&token, item);
3154 btrfs_set_token_item_offset(&token, item, ioff + rt_data_off);
3157 btrfs_set_header_nritems(l, mid);
3158 btrfs_item_key(right, &disk_key, 0);
3159 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
3161 btrfs_mark_buffer_dirty(right);
3162 btrfs_mark_buffer_dirty(l);
3163 BUG_ON(path->slots[0] != slot);
3166 btrfs_tree_unlock(path->nodes[0]);
3167 free_extent_buffer(path->nodes[0]);
3168 path->nodes[0] = right;
3169 path->slots[0] -= mid;
3170 path->slots[1] += 1;
3172 btrfs_tree_unlock(right);
3173 free_extent_buffer(right);
3176 BUG_ON(path->slots[0] < 0);
3180 * double splits happen when we need to insert a big item in the middle
3181 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3182 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3185 * We avoid this by trying to push the items on either side of our target
3186 * into the adjacent leaves. If all goes well we can avoid the double split
3189 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3190 struct btrfs_root *root,
3191 struct btrfs_path *path,
3198 int space_needed = data_size;
3200 slot = path->slots[0];
3201 if (slot < btrfs_header_nritems(path->nodes[0]))
3202 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3205 * try to push all the items after our slot into the
3208 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
3215 nritems = btrfs_header_nritems(path->nodes[0]);
3217 * our goal is to get our slot at the start or end of a leaf. If
3218 * we've done so we're done
3220 if (path->slots[0] == 0 || path->slots[0] == nritems)
3223 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3226 /* try to push all the items before our slot into the next leaf */
3227 slot = path->slots[0];
3228 space_needed = data_size;
3230 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
3231 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
3244 * split the path's leaf in two, making sure there is at least data_size
3245 * available for the resulting leaf level of the path.
3247 * returns 0 if all went well and < 0 on failure.
3249 static noinline int split_leaf(struct btrfs_trans_handle *trans,
3250 struct btrfs_root *root,
3251 const struct btrfs_key *ins_key,
3252 struct btrfs_path *path, int data_size,
3255 struct btrfs_disk_key disk_key;
3256 struct extent_buffer *l;
3260 struct extent_buffer *right;
3261 struct btrfs_fs_info *fs_info = root->fs_info;
3265 int num_doubles = 0;
3266 int tried_avoid_double = 0;
3269 slot = path->slots[0];
3270 if (extend && data_size + btrfs_item_size_nr(l, slot) +
3271 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
3274 /* first try to make some room by pushing left and right */
3275 if (data_size && path->nodes[1]) {
3276 int space_needed = data_size;
3278 if (slot < btrfs_header_nritems(l))
3279 space_needed -= btrfs_leaf_free_space(l);
3281 wret = push_leaf_right(trans, root, path, space_needed,
3282 space_needed, 0, 0);
3286 space_needed = data_size;
3288 space_needed -= btrfs_leaf_free_space(l);
3289 wret = push_leaf_left(trans, root, path, space_needed,
3290 space_needed, 0, (u32)-1);
3296 /* did the pushes work? */
3297 if (btrfs_leaf_free_space(l) >= data_size)
3301 if (!path->nodes[1]) {
3302 ret = insert_new_root(trans, root, path, 1);
3309 slot = path->slots[0];
3310 nritems = btrfs_header_nritems(l);
3311 mid = (nritems + 1) / 2;
3315 leaf_space_used(l, mid, nritems - mid) + data_size >
3316 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3317 if (slot >= nritems) {
3321 if (mid != nritems &&
3322 leaf_space_used(l, mid, nritems - mid) +
3323 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3324 if (data_size && !tried_avoid_double)
3325 goto push_for_double;
3331 if (leaf_space_used(l, 0, mid) + data_size >
3332 BTRFS_LEAF_DATA_SIZE(fs_info)) {
3333 if (!extend && data_size && slot == 0) {
3335 } else if ((extend || !data_size) && slot == 0) {
3339 if (mid != nritems &&
3340 leaf_space_used(l, mid, nritems - mid) +
3341 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
3342 if (data_size && !tried_avoid_double)
3343 goto push_for_double;
3351 btrfs_cpu_key_to_disk(&disk_key, ins_key);
3353 btrfs_item_key(l, &disk_key, mid);
3356 * We have to about BTRFS_NESTING_NEW_ROOT here if we've done a double
3357 * split, because we're only allowed to have MAX_LOCKDEP_SUBCLASSES
3358 * subclasses, which is 8 at the time of this patch, and we've maxed it
3359 * out. In the future we could add a
3360 * BTRFS_NESTING_SPLIT_THE_SPLITTENING if we need to, but for now just
3361 * use BTRFS_NESTING_NEW_ROOT.
3363 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3364 &disk_key, 0, l->start, 0,
3365 num_doubles ? BTRFS_NESTING_NEW_ROOT :
3366 BTRFS_NESTING_SPLIT);
3368 return PTR_ERR(right);
3370 root_add_used(root, fs_info->nodesize);
3374 btrfs_set_header_nritems(right, 0);
3375 insert_ptr(trans, path, &disk_key,
3376 right->start, path->slots[1] + 1, 1);
3377 btrfs_tree_unlock(path->nodes[0]);
3378 free_extent_buffer(path->nodes[0]);
3379 path->nodes[0] = right;
3381 path->slots[1] += 1;
3383 btrfs_set_header_nritems(right, 0);
3384 insert_ptr(trans, path, &disk_key,
3385 right->start, path->slots[1], 1);
3386 btrfs_tree_unlock(path->nodes[0]);
3387 free_extent_buffer(path->nodes[0]);
3388 path->nodes[0] = right;
3390 if (path->slots[1] == 0)
3391 fixup_low_keys(path, &disk_key, 1);
3394 * We create a new leaf 'right' for the required ins_len and
3395 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
3396 * the content of ins_len to 'right'.
3401 copy_for_split(trans, path, l, right, slot, mid, nritems);
3404 BUG_ON(num_doubles != 0);
3412 push_for_double_split(trans, root, path, data_size);
3413 tried_avoid_double = 1;
3414 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
3419 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
3420 struct btrfs_root *root,
3421 struct btrfs_path *path, int ins_len)
3423 struct btrfs_key key;
3424 struct extent_buffer *leaf;
3425 struct btrfs_file_extent_item *fi;
3430 leaf = path->nodes[0];
3431 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
3433 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
3434 key.type != BTRFS_EXTENT_CSUM_KEY);
3436 if (btrfs_leaf_free_space(leaf) >= ins_len)
3439 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3440 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3441 fi = btrfs_item_ptr(leaf, path->slots[0],
3442 struct btrfs_file_extent_item);
3443 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
3445 btrfs_release_path(path);
3447 path->keep_locks = 1;
3448 path->search_for_split = 1;
3449 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
3450 path->search_for_split = 0;
3457 leaf = path->nodes[0];
3458 /* if our item isn't there, return now */
3459 if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
3462 /* the leaf has changed, it now has room. return now */
3463 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
3466 if (key.type == BTRFS_EXTENT_DATA_KEY) {
3467 fi = btrfs_item_ptr(leaf, path->slots[0],
3468 struct btrfs_file_extent_item);
3469 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
3473 ret = split_leaf(trans, root, &key, path, ins_len, 1);
3477 path->keep_locks = 0;
3478 btrfs_unlock_up_safe(path, 1);
3481 path->keep_locks = 0;
3485 static noinline int split_item(struct btrfs_path *path,
3486 const struct btrfs_key *new_key,
3487 unsigned long split_offset)
3489 struct extent_buffer *leaf;
3490 struct btrfs_item *item;
3491 struct btrfs_item *new_item;
3497 struct btrfs_disk_key disk_key;
3499 leaf = path->nodes[0];
3500 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
3502 item = btrfs_item_nr(path->slots[0]);
3503 orig_offset = btrfs_item_offset(leaf, item);
3504 item_size = btrfs_item_size(leaf, item);
3506 buf = kmalloc(item_size, GFP_NOFS);
3510 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
3511 path->slots[0]), item_size);
3513 slot = path->slots[0] + 1;
3514 nritems = btrfs_header_nritems(leaf);
3515 if (slot != nritems) {
3516 /* shift the items */
3517 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
3518 btrfs_item_nr_offset(slot),
3519 (nritems - slot) * sizeof(struct btrfs_item));
3522 btrfs_cpu_key_to_disk(&disk_key, new_key);
3523 btrfs_set_item_key(leaf, &disk_key, slot);
3525 new_item = btrfs_item_nr(slot);
3527 btrfs_set_item_offset(leaf, new_item, orig_offset);
3528 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
3530 btrfs_set_item_offset(leaf, item,
3531 orig_offset + item_size - split_offset);
3532 btrfs_set_item_size(leaf, item, split_offset);
3534 btrfs_set_header_nritems(leaf, nritems + 1);
3536 /* write the data for the start of the original item */
3537 write_extent_buffer(leaf, buf,
3538 btrfs_item_ptr_offset(leaf, path->slots[0]),
3541 /* write the data for the new item */
3542 write_extent_buffer(leaf, buf + split_offset,
3543 btrfs_item_ptr_offset(leaf, slot),
3544 item_size - split_offset);
3545 btrfs_mark_buffer_dirty(leaf);
3547 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
3553 * This function splits a single item into two items,
3554 * giving 'new_key' to the new item and splitting the
3555 * old one at split_offset (from the start of the item).
3557 * The path may be released by this operation. After
3558 * the split, the path is pointing to the old item. The
3559 * new item is going to be in the same node as the old one.
3561 * Note, the item being split must be smaller enough to live alone on
3562 * a tree block with room for one extra struct btrfs_item
3564 * This allows us to split the item in place, keeping a lock on the
3565 * leaf the entire time.
3567 int btrfs_split_item(struct btrfs_trans_handle *trans,
3568 struct btrfs_root *root,
3569 struct btrfs_path *path,
3570 const struct btrfs_key *new_key,
3571 unsigned long split_offset)
3574 ret = setup_leaf_for_split(trans, root, path,
3575 sizeof(struct btrfs_item));
3579 ret = split_item(path, new_key, split_offset);
3584 * This function duplicate a item, giving 'new_key' to the new item.
3585 * It guarantees both items live in the same tree leaf and the new item
3586 * is contiguous with the original item.
3588 * This allows us to split file extent in place, keeping a lock on the
3589 * leaf the entire time.
3591 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
3592 struct btrfs_root *root,
3593 struct btrfs_path *path,
3594 const struct btrfs_key *new_key)
3596 struct extent_buffer *leaf;
3600 leaf = path->nodes[0];
3601 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
3602 ret = setup_leaf_for_split(trans, root, path,
3603 item_size + sizeof(struct btrfs_item));
3608 setup_items_for_insert(root, path, new_key, &item_size, 1);
3609 leaf = path->nodes[0];
3610 memcpy_extent_buffer(leaf,
3611 btrfs_item_ptr_offset(leaf, path->slots[0]),
3612 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
3618 * make the item pointed to by the path smaller. new_size indicates
3619 * how small to make it, and from_end tells us if we just chop bytes
3620 * off the end of the item or if we shift the item to chop bytes off
3623 void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
3626 struct extent_buffer *leaf;
3627 struct btrfs_item *item;
3629 unsigned int data_end;
3630 unsigned int old_data_start;
3631 unsigned int old_size;
3632 unsigned int size_diff;
3634 struct btrfs_map_token token;
3636 leaf = path->nodes[0];
3637 slot = path->slots[0];
3639 old_size = btrfs_item_size_nr(leaf, slot);
3640 if (old_size == new_size)
3643 nritems = btrfs_header_nritems(leaf);
3644 data_end = leaf_data_end(leaf);
3646 old_data_start = btrfs_item_offset_nr(leaf, slot);
3648 size_diff = old_size - new_size;
3651 BUG_ON(slot >= nritems);
3654 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3656 /* first correct the data pointers */
3657 btrfs_init_map_token(&token, leaf);
3658 for (i = slot; i < nritems; i++) {
3660 item = btrfs_item_nr(i);
3662 ioff = btrfs_token_item_offset(&token, item);
3663 btrfs_set_token_item_offset(&token, item, ioff + size_diff);
3666 /* shift the data */
3668 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3669 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3670 data_end, old_data_start + new_size - data_end);
3672 struct btrfs_disk_key disk_key;
3675 btrfs_item_key(leaf, &disk_key, slot);
3677 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
3679 struct btrfs_file_extent_item *fi;
3681 fi = btrfs_item_ptr(leaf, slot,
3682 struct btrfs_file_extent_item);
3683 fi = (struct btrfs_file_extent_item *)(
3684 (unsigned long)fi - size_diff);
3686 if (btrfs_file_extent_type(leaf, fi) ==
3687 BTRFS_FILE_EXTENT_INLINE) {
3688 ptr = btrfs_item_ptr_offset(leaf, slot);
3689 memmove_extent_buffer(leaf, ptr,
3691 BTRFS_FILE_EXTENT_INLINE_DATA_START);
3695 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3696 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
3697 data_end, old_data_start - data_end);
3699 offset = btrfs_disk_key_offset(&disk_key);
3700 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
3701 btrfs_set_item_key(leaf, &disk_key, slot);
3703 fixup_low_keys(path, &disk_key, 1);
3706 item = btrfs_item_nr(slot);
3707 btrfs_set_item_size(leaf, item, new_size);
3708 btrfs_mark_buffer_dirty(leaf);
3710 if (btrfs_leaf_free_space(leaf) < 0) {
3711 btrfs_print_leaf(leaf);
3717 * make the item pointed to by the path bigger, data_size is the added size.
3719 void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
3722 struct extent_buffer *leaf;
3723 struct btrfs_item *item;
3725 unsigned int data_end;
3726 unsigned int old_data;
3727 unsigned int old_size;
3729 struct btrfs_map_token token;
3731 leaf = path->nodes[0];
3733 nritems = btrfs_header_nritems(leaf);
3734 data_end = leaf_data_end(leaf);
3736 if (btrfs_leaf_free_space(leaf) < data_size) {
3737 btrfs_print_leaf(leaf);
3740 slot = path->slots[0];
3741 old_data = btrfs_item_end_nr(leaf, slot);
3744 if (slot >= nritems) {
3745 btrfs_print_leaf(leaf);
3746 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
3752 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3754 /* first correct the data pointers */
3755 btrfs_init_map_token(&token, leaf);
3756 for (i = slot; i < nritems; i++) {
3758 item = btrfs_item_nr(i);
3760 ioff = btrfs_token_item_offset(&token, item);
3761 btrfs_set_token_item_offset(&token, item, ioff - data_size);
3764 /* shift the data */
3765 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3766 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
3767 data_end, old_data - data_end);
3769 data_end = old_data;
3770 old_size = btrfs_item_size_nr(leaf, slot);
3771 item = btrfs_item_nr(slot);
3772 btrfs_set_item_size(leaf, item, old_size + data_size);
3773 btrfs_mark_buffer_dirty(leaf);
3775 if (btrfs_leaf_free_space(leaf) < 0) {
3776 btrfs_print_leaf(leaf);
3782 * setup_items_for_insert - Helper called before inserting one or more items
3783 * to a leaf. Main purpose is to save stack depth by doing the bulk of the work
3784 * in a function that doesn't call btrfs_search_slot
3786 * @root: root we are inserting items to
3787 * @path: points to the leaf/slot where we are going to insert new items
3788 * @cpu_key: array of keys for items to be inserted
3789 * @data_size: size of the body of each item we are going to insert
3790 * @nr: size of @cpu_key/@data_size arrays
3792 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
3793 const struct btrfs_key *cpu_key, u32 *data_size,
3796 struct btrfs_fs_info *fs_info = root->fs_info;
3797 struct btrfs_item *item;
3800 unsigned int data_end;
3801 struct btrfs_disk_key disk_key;
3802 struct extent_buffer *leaf;
3804 struct btrfs_map_token token;
3808 for (i = 0; i < nr; i++)
3809 total_data += data_size[i];
3810 total_size = total_data + (nr * sizeof(struct btrfs_item));
3812 if (path->slots[0] == 0) {
3813 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
3814 fixup_low_keys(path, &disk_key, 1);
3816 btrfs_unlock_up_safe(path, 1);
3818 leaf = path->nodes[0];
3819 slot = path->slots[0];
3821 nritems = btrfs_header_nritems(leaf);
3822 data_end = leaf_data_end(leaf);
3824 if (btrfs_leaf_free_space(leaf) < total_size) {
3825 btrfs_print_leaf(leaf);
3826 btrfs_crit(fs_info, "not enough freespace need %u have %d",
3827 total_size, btrfs_leaf_free_space(leaf));
3831 btrfs_init_map_token(&token, leaf);
3832 if (slot != nritems) {
3833 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
3835 if (old_data < data_end) {
3836 btrfs_print_leaf(leaf);
3838 "item at slot %d with data offset %u beyond data end of leaf %u",
3839 slot, old_data, data_end);
3843 * item0..itemN ... dataN.offset..dataN.size .. data0.size
3845 /* first correct the data pointers */
3846 for (i = slot; i < nritems; i++) {
3849 item = btrfs_item_nr(i);
3850 ioff = btrfs_token_item_offset(&token, item);
3851 btrfs_set_token_item_offset(&token, item,
3854 /* shift the items */
3855 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
3856 btrfs_item_nr_offset(slot),
3857 (nritems - slot) * sizeof(struct btrfs_item));
3859 /* shift the data */
3860 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
3861 data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
3862 data_end, old_data - data_end);
3863 data_end = old_data;
3866 /* setup the item for the new data */
3867 for (i = 0; i < nr; i++) {
3868 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
3869 btrfs_set_item_key(leaf, &disk_key, slot + i);
3870 item = btrfs_item_nr(slot + i);
3871 data_end -= data_size[i];
3872 btrfs_set_token_item_offset(&token, item, data_end);
3873 btrfs_set_token_item_size(&token, item, data_size[i]);
3876 btrfs_set_header_nritems(leaf, nritems + nr);
3877 btrfs_mark_buffer_dirty(leaf);
3879 if (btrfs_leaf_free_space(leaf) < 0) {
3880 btrfs_print_leaf(leaf);
3886 * Given a key and some data, insert items into the tree.
3887 * This does all the path init required, making room in the tree if needed.
3889 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
3890 struct btrfs_root *root,
3891 struct btrfs_path *path,
3892 const struct btrfs_key *cpu_key, u32 *data_size,
3901 for (i = 0; i < nr; i++)
3902 total_data += data_size[i];
3904 total_size = total_data + (nr * sizeof(struct btrfs_item));
3905 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
3911 slot = path->slots[0];
3914 setup_items_for_insert(root, path, cpu_key, data_size, nr);
3919 * Given a key and some data, insert an item into the tree.
3920 * This does all the path init required, making room in the tree if needed.
3922 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
3923 const struct btrfs_key *cpu_key, void *data,
3927 struct btrfs_path *path;
3928 struct extent_buffer *leaf;
3931 path = btrfs_alloc_path();
3934 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
3936 leaf = path->nodes[0];
3937 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
3938 write_extent_buffer(leaf, data, ptr, data_size);
3939 btrfs_mark_buffer_dirty(leaf);
3941 btrfs_free_path(path);
3946 * delete the pointer from a given node.
3948 * the tree should have been previously balanced so the deletion does not
3951 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
3952 int level, int slot)
3954 struct extent_buffer *parent = path->nodes[level];
3958 nritems = btrfs_header_nritems(parent);
3959 if (slot != nritems - 1) {
3961 ret = btrfs_tree_mod_log_insert_move(parent, slot,
3962 slot + 1, nritems - slot - 1);
3965 memmove_extent_buffer(parent,
3966 btrfs_node_key_ptr_offset(slot),
3967 btrfs_node_key_ptr_offset(slot + 1),
3968 sizeof(struct btrfs_key_ptr) *
3969 (nritems - slot - 1));
3971 ret = btrfs_tree_mod_log_insert_key(parent, slot,
3972 BTRFS_MOD_LOG_KEY_REMOVE, GFP_NOFS);
3977 btrfs_set_header_nritems(parent, nritems);
3978 if (nritems == 0 && parent == root->node) {
3979 BUG_ON(btrfs_header_level(root->node) != 1);
3980 /* just turn the root into a leaf and break */
3981 btrfs_set_header_level(root->node, 0);
3982 } else if (slot == 0) {
3983 struct btrfs_disk_key disk_key;
3985 btrfs_node_key(parent, &disk_key, 0);
3986 fixup_low_keys(path, &disk_key, level + 1);
3988 btrfs_mark_buffer_dirty(parent);
3992 * a helper function to delete the leaf pointed to by path->slots[1] and
3995 * This deletes the pointer in path->nodes[1] and frees the leaf
3996 * block extent. zero is returned if it all worked out, < 0 otherwise.
3998 * The path must have already been setup for deleting the leaf, including
3999 * all the proper balancing. path->nodes[1] must be locked.
4001 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4002 struct btrfs_root *root,
4003 struct btrfs_path *path,
4004 struct extent_buffer *leaf)
4006 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4007 del_ptr(root, path, 1, path->slots[1]);
4010 * btrfs_free_extent is expensive, we want to make sure we
4011 * aren't holding any locks when we call it
4013 btrfs_unlock_up_safe(path, 0);
4015 root_sub_used(root, leaf->len);
4017 atomic_inc(&leaf->refs);
4018 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4019 free_extent_buffer_stale(leaf);
4022 * delete the item at the leaf level in path. If that empties
4023 * the leaf, remove it from the tree
4025 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4026 struct btrfs_path *path, int slot, int nr)
4028 struct btrfs_fs_info *fs_info = root->fs_info;
4029 struct extent_buffer *leaf;
4030 struct btrfs_item *item;
4038 leaf = path->nodes[0];
4039 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4041 for (i = 0; i < nr; i++)
4042 dsize += btrfs_item_size_nr(leaf, slot + i);
4044 nritems = btrfs_header_nritems(leaf);
4046 if (slot + nr != nritems) {
4047 int data_end = leaf_data_end(leaf);
4048 struct btrfs_map_token token;
4050 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4052 BTRFS_LEAF_DATA_OFFSET + data_end,
4053 last_off - data_end);
4055 btrfs_init_map_token(&token, leaf);
4056 for (i = slot + nr; i < nritems; i++) {
4059 item = btrfs_item_nr(i);
4060 ioff = btrfs_token_item_offset(&token, item);
4061 btrfs_set_token_item_offset(&token, item, ioff + dsize);
4064 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4065 btrfs_item_nr_offset(slot + nr),
4066 sizeof(struct btrfs_item) *
4067 (nritems - slot - nr));
4069 btrfs_set_header_nritems(leaf, nritems - nr);
4072 /* delete the leaf if we've emptied it */
4074 if (leaf == root->node) {
4075 btrfs_set_header_level(leaf, 0);
4077 btrfs_clean_tree_block(leaf);
4078 btrfs_del_leaf(trans, root, path, leaf);
4081 int used = leaf_space_used(leaf, 0, nritems);
4083 struct btrfs_disk_key disk_key;
4085 btrfs_item_key(leaf, &disk_key, 0);
4086 fixup_low_keys(path, &disk_key, 1);
4089 /* delete the leaf if it is mostly empty */
4090 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
4091 /* push_leaf_left fixes the path.
4092 * make sure the path still points to our leaf
4093 * for possible call to del_ptr below
4095 slot = path->slots[1];
4096 atomic_inc(&leaf->refs);
4098 wret = push_leaf_left(trans, root, path, 1, 1,
4100 if (wret < 0 && wret != -ENOSPC)
4103 if (path->nodes[0] == leaf &&
4104 btrfs_header_nritems(leaf)) {
4105 wret = push_leaf_right(trans, root, path, 1,
4107 if (wret < 0 && wret != -ENOSPC)
4111 if (btrfs_header_nritems(leaf) == 0) {
4112 path->slots[1] = slot;
4113 btrfs_del_leaf(trans, root, path, leaf);
4114 free_extent_buffer(leaf);
4117 /* if we're still in the path, make sure
4118 * we're dirty. Otherwise, one of the
4119 * push_leaf functions must have already
4120 * dirtied this buffer
4122 if (path->nodes[0] == leaf)
4123 btrfs_mark_buffer_dirty(leaf);
4124 free_extent_buffer(leaf);
4127 btrfs_mark_buffer_dirty(leaf);
4134 * search the tree again to find a leaf with lesser keys
4135 * returns 0 if it found something or 1 if there are no lesser leaves.
4136 * returns < 0 on io errors.
4138 * This may release the path, and so you may lose any locks held at the
4141 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4143 struct btrfs_key key;
4144 struct btrfs_disk_key found_key;
4147 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4149 if (key.offset > 0) {
4151 } else if (key.type > 0) {
4153 key.offset = (u64)-1;
4154 } else if (key.objectid > 0) {
4157 key.offset = (u64)-1;
4162 btrfs_release_path(path);
4163 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4166 btrfs_item_key(path->nodes[0], &found_key, 0);
4167 ret = comp_keys(&found_key, &key);
4169 * We might have had an item with the previous key in the tree right
4170 * before we released our path. And after we released our path, that
4171 * item might have been pushed to the first slot (0) of the leaf we
4172 * were holding due to a tree balance. Alternatively, an item with the
4173 * previous key can exist as the only element of a leaf (big fat item).
4174 * Therefore account for these 2 cases, so that our callers (like
4175 * btrfs_previous_item) don't miss an existing item with a key matching
4176 * the previous key we computed above.
4184 * A helper function to walk down the tree starting at min_key, and looking
4185 * for nodes or leaves that are have a minimum transaction id.
4186 * This is used by the btree defrag code, and tree logging
4188 * This does not cow, but it does stuff the starting key it finds back
4189 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4190 * key and get a writable path.
4192 * This honors path->lowest_level to prevent descent past a given level
4195 * min_trans indicates the oldest transaction that you are interested
4196 * in walking through. Any nodes or leaves older than min_trans are
4197 * skipped over (without reading them).
4199 * returns zero if something useful was found, < 0 on error and 1 if there
4200 * was nothing in the tree that matched the search criteria.
4202 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4203 struct btrfs_path *path,
4206 struct extent_buffer *cur;
4207 struct btrfs_key found_key;
4213 int keep_locks = path->keep_locks;
4215 path->keep_locks = 1;
4217 cur = btrfs_read_lock_root_node(root);
4218 level = btrfs_header_level(cur);
4219 WARN_ON(path->nodes[level]);
4220 path->nodes[level] = cur;
4221 path->locks[level] = BTRFS_READ_LOCK;
4223 if (btrfs_header_generation(cur) < min_trans) {
4228 nritems = btrfs_header_nritems(cur);
4229 level = btrfs_header_level(cur);
4230 sret = btrfs_bin_search(cur, min_key, &slot);
4236 /* at the lowest level, we're done, setup the path and exit */
4237 if (level == path->lowest_level) {
4238 if (slot >= nritems)
4241 path->slots[level] = slot;
4242 btrfs_item_key_to_cpu(cur, &found_key, slot);
4245 if (sret && slot > 0)
4248 * check this node pointer against the min_trans parameters.
4249 * If it is too old, skip to the next one.
4251 while (slot < nritems) {
4254 gen = btrfs_node_ptr_generation(cur, slot);
4255 if (gen < min_trans) {
4263 * we didn't find a candidate key in this node, walk forward
4264 * and find another one
4266 if (slot >= nritems) {
4267 path->slots[level] = slot;
4268 sret = btrfs_find_next_key(root, path, min_key, level,
4271 btrfs_release_path(path);
4277 /* save our key for returning back */
4278 btrfs_node_key_to_cpu(cur, &found_key, slot);
4279 path->slots[level] = slot;
4280 if (level == path->lowest_level) {
4284 cur = btrfs_read_node_slot(cur, slot);
4290 btrfs_tree_read_lock(cur);
4292 path->locks[level - 1] = BTRFS_READ_LOCK;
4293 path->nodes[level - 1] = cur;
4294 unlock_up(path, level, 1, 0, NULL);
4297 path->keep_locks = keep_locks;
4299 btrfs_unlock_up_safe(path, path->lowest_level + 1);
4300 memcpy(min_key, &found_key, sizeof(found_key));
4306 * this is similar to btrfs_next_leaf, but does not try to preserve
4307 * and fixup the path. It looks for and returns the next key in the
4308 * tree based on the current path and the min_trans parameters.
4310 * 0 is returned if another key is found, < 0 if there are any errors
4311 * and 1 is returned if there are no higher keys in the tree
4313 * path->keep_locks should be set to 1 on the search made before
4314 * calling this function.
4316 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
4317 struct btrfs_key *key, int level, u64 min_trans)
4320 struct extent_buffer *c;
4322 WARN_ON(!path->keep_locks && !path->skip_locking);
4323 while (level < BTRFS_MAX_LEVEL) {
4324 if (!path->nodes[level])
4327 slot = path->slots[level] + 1;
4328 c = path->nodes[level];
4330 if (slot >= btrfs_header_nritems(c)) {
4333 struct btrfs_key cur_key;
4334 if (level + 1 >= BTRFS_MAX_LEVEL ||
4335 !path->nodes[level + 1])
4338 if (path->locks[level + 1] || path->skip_locking) {
4343 slot = btrfs_header_nritems(c) - 1;
4345 btrfs_item_key_to_cpu(c, &cur_key, slot);
4347 btrfs_node_key_to_cpu(c, &cur_key, slot);
4349 orig_lowest = path->lowest_level;
4350 btrfs_release_path(path);
4351 path->lowest_level = level;
4352 ret = btrfs_search_slot(NULL, root, &cur_key, path,
4354 path->lowest_level = orig_lowest;
4358 c = path->nodes[level];
4359 slot = path->slots[level];
4366 btrfs_item_key_to_cpu(c, key, slot);
4368 u64 gen = btrfs_node_ptr_generation(c, slot);
4370 if (gen < min_trans) {
4374 btrfs_node_key_to_cpu(c, key, slot);
4381 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
4386 struct extent_buffer *c;
4387 struct extent_buffer *next;
4388 struct btrfs_key key;
4393 nritems = btrfs_header_nritems(path->nodes[0]);
4397 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
4401 btrfs_release_path(path);
4403 path->keep_locks = 1;
4406 ret = btrfs_search_old_slot(root, &key, path, time_seq);
4408 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4409 path->keep_locks = 0;
4414 nritems = btrfs_header_nritems(path->nodes[0]);
4416 * by releasing the path above we dropped all our locks. A balance
4417 * could have added more items next to the key that used to be
4418 * at the very end of the block. So, check again here and
4419 * advance the path if there are now more items available.
4421 if (nritems > 0 && path->slots[0] < nritems - 1) {
4428 * So the above check misses one case:
4429 * - after releasing the path above, someone has removed the item that
4430 * used to be at the very end of the block, and balance between leafs
4431 * gets another one with bigger key.offset to replace it.
4433 * This one should be returned as well, or we can get leaf corruption
4434 * later(esp. in __btrfs_drop_extents()).
4436 * And a bit more explanation about this check,
4437 * with ret > 0, the key isn't found, the path points to the slot
4438 * where it should be inserted, so the path->slots[0] item must be the
4441 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
4446 while (level < BTRFS_MAX_LEVEL) {
4447 if (!path->nodes[level]) {
4452 slot = path->slots[level] + 1;
4453 c = path->nodes[level];
4454 if (slot >= btrfs_header_nritems(c)) {
4456 if (level == BTRFS_MAX_LEVEL) {
4465 * Our current level is where we're going to start from, and to
4466 * make sure lockdep doesn't complain we need to drop our locks
4467 * and nodes from 0 to our current level.
4469 for (i = 0; i < level; i++) {
4470 if (path->locks[level]) {
4471 btrfs_tree_read_unlock(path->nodes[i]);
4474 free_extent_buffer(path->nodes[i]);
4475 path->nodes[i] = NULL;
4479 ret = read_block_for_search(root, path, &next, level,
4485 btrfs_release_path(path);
4489 if (!path->skip_locking) {
4490 ret = btrfs_try_tree_read_lock(next);
4491 if (!ret && time_seq) {
4493 * If we don't get the lock, we may be racing
4494 * with push_leaf_left, holding that lock while
4495 * itself waiting for the leaf we've currently
4496 * locked. To solve this situation, we give up
4497 * on our lock and cycle.
4499 free_extent_buffer(next);
4500 btrfs_release_path(path);
4505 btrfs_tree_read_lock(next);
4509 path->slots[level] = slot;
4512 path->nodes[level] = next;
4513 path->slots[level] = 0;
4514 if (!path->skip_locking)
4515 path->locks[level] = BTRFS_READ_LOCK;
4519 ret = read_block_for_search(root, path, &next, level,
4525 btrfs_release_path(path);
4529 if (!path->skip_locking)
4530 btrfs_tree_read_lock(next);
4534 unlock_up(path, 0, 1, 0, NULL);
4540 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
4541 * searching until it gets past min_objectid or finds an item of 'type'
4543 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4545 int btrfs_previous_item(struct btrfs_root *root,
4546 struct btrfs_path *path, u64 min_objectid,
4549 struct btrfs_key found_key;
4550 struct extent_buffer *leaf;
4555 if (path->slots[0] == 0) {
4556 ret = btrfs_prev_leaf(root, path);
4562 leaf = path->nodes[0];
4563 nritems = btrfs_header_nritems(leaf);
4566 if (path->slots[0] == nritems)
4569 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4570 if (found_key.objectid < min_objectid)
4572 if (found_key.type == type)
4574 if (found_key.objectid == min_objectid &&
4575 found_key.type < type)
4582 * search in extent tree to find a previous Metadata/Data extent item with
4585 * returns 0 if something is found, 1 if nothing was found and < 0 on error
4587 int btrfs_previous_extent_item(struct btrfs_root *root,
4588 struct btrfs_path *path, u64 min_objectid)
4590 struct btrfs_key found_key;
4591 struct extent_buffer *leaf;
4596 if (path->slots[0] == 0) {
4597 ret = btrfs_prev_leaf(root, path);
4603 leaf = path->nodes[0];
4604 nritems = btrfs_header_nritems(leaf);
4607 if (path->slots[0] == nritems)
4610 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
4611 if (found_key.objectid < min_objectid)
4613 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
4614 found_key.type == BTRFS_METADATA_ITEM_KEY)
4616 if (found_key.objectid == min_objectid &&
4617 found_key.type < BTRFS_EXTENT_ITEM_KEY)