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"
18 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
19 *root, struct btrfs_path *path, int level);
20 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root *root,
21 const struct btrfs_key *ins_key, struct btrfs_path *path,
22 int data_size, int extend);
23 static int push_node_left(struct btrfs_trans_handle *trans,
24 struct extent_buffer *dst,
25 struct extent_buffer *src, int empty);
26 static int balance_node_right(struct btrfs_trans_handle *trans,
27 struct extent_buffer *dst_buf,
28 struct extent_buffer *src_buf);
29 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
32 static const struct btrfs_csums {
37 [BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
38 [BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
39 [BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
40 [BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
41 .driver = "blake2b-256" },
44 int btrfs_super_csum_size(const struct btrfs_super_block *s)
46 u16 t = btrfs_super_csum_type(s);
48 * csum type is validated at mount time
50 return btrfs_csums[t].size;
53 const char *btrfs_super_csum_name(u16 csum_type)
55 /* csum type is validated at mount time */
56 return btrfs_csums[csum_type].name;
60 * Return driver name if defined, otherwise the name that's also a valid driver
63 const char *btrfs_super_csum_driver(u16 csum_type)
65 /* csum type is validated at mount time */
66 return btrfs_csums[csum_type].driver ?:
67 btrfs_csums[csum_type].name;
70 size_t __const btrfs_get_num_csums(void)
72 return ARRAY_SIZE(btrfs_csums);
75 struct btrfs_path *btrfs_alloc_path(void)
77 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
80 /* this also releases the path */
81 void btrfs_free_path(struct btrfs_path *p)
85 btrfs_release_path(p);
86 kmem_cache_free(btrfs_path_cachep, p);
90 * path release drops references on the extent buffers in the path
91 * and it drops any locks held by this path
93 * It is safe to call this on paths that no locks or extent buffers held.
95 noinline void btrfs_release_path(struct btrfs_path *p)
99 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
104 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
107 free_extent_buffer(p->nodes[i]);
113 * safely gets a reference on the root node of a tree. A lock
114 * is not taken, so a concurrent writer may put a different node
115 * at the root of the tree. See btrfs_lock_root_node for the
118 * The extent buffer returned by this has a reference taken, so
119 * it won't disappear. It may stop being the root of the tree
120 * at any time because there are no locks held.
122 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
124 struct extent_buffer *eb;
128 eb = rcu_dereference(root->node);
131 * RCU really hurts here, we could free up the root node because
132 * it was COWed but we may not get the new root node yet so do
133 * the inc_not_zero dance and if it doesn't work then
134 * synchronize_rcu and try again.
136 if (atomic_inc_not_zero(&eb->refs)) {
146 /* loop around taking references on and locking the root node of the
147 * tree until you end up with a lock on the root. A locked buffer
148 * is returned, with a reference held.
150 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
152 struct extent_buffer *eb;
155 eb = btrfs_root_node(root);
157 if (eb == root->node)
159 btrfs_tree_unlock(eb);
160 free_extent_buffer(eb);
165 /* loop around taking references on and locking the root node of the
166 * tree until you end up with a lock on the root. A locked buffer
167 * is returned, with a reference held.
169 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
171 struct extent_buffer *eb;
174 eb = btrfs_root_node(root);
175 btrfs_tree_read_lock(eb);
176 if (eb == root->node)
178 btrfs_tree_read_unlock(eb);
179 free_extent_buffer(eb);
184 /* cowonly root (everything not a reference counted cow subvolume), just get
185 * put onto a simple dirty list. transaction.c walks this to make sure they
186 * get properly updated on disk.
188 static void add_root_to_dirty_list(struct btrfs_root *root)
190 struct btrfs_fs_info *fs_info = root->fs_info;
192 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
193 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
196 spin_lock(&fs_info->trans_lock);
197 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
198 /* Want the extent tree to be the last on the list */
199 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
200 list_move_tail(&root->dirty_list,
201 &fs_info->dirty_cowonly_roots);
203 list_move(&root->dirty_list,
204 &fs_info->dirty_cowonly_roots);
206 spin_unlock(&fs_info->trans_lock);
210 * used by snapshot creation to make a copy of a root for a tree with
211 * a given objectid. The buffer with the new root node is returned in
212 * cow_ret, and this func returns zero on success or a negative error code.
214 int btrfs_copy_root(struct btrfs_trans_handle *trans,
215 struct btrfs_root *root,
216 struct extent_buffer *buf,
217 struct extent_buffer **cow_ret, u64 new_root_objectid)
219 struct btrfs_fs_info *fs_info = root->fs_info;
220 struct extent_buffer *cow;
223 struct btrfs_disk_key disk_key;
225 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
226 trans->transid != fs_info->running_transaction->transid);
227 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
228 trans->transid != root->last_trans);
230 level = btrfs_header_level(buf);
232 btrfs_item_key(buf, &disk_key, 0);
234 btrfs_node_key(buf, &disk_key, 0);
236 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
237 &disk_key, level, buf->start, 0);
241 copy_extent_buffer_full(cow, buf);
242 btrfs_set_header_bytenr(cow, cow->start);
243 btrfs_set_header_generation(cow, trans->transid);
244 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
245 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
246 BTRFS_HEADER_FLAG_RELOC);
247 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
248 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
250 btrfs_set_header_owner(cow, new_root_objectid);
252 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
254 WARN_ON(btrfs_header_generation(buf) > trans->transid);
255 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
256 ret = btrfs_inc_ref(trans, root, cow, 1);
258 ret = btrfs_inc_ref(trans, root, cow, 0);
263 btrfs_mark_buffer_dirty(cow);
272 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
273 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
275 MOD_LOG_ROOT_REPLACE,
278 struct tree_mod_root {
283 struct tree_mod_elem {
289 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
292 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
295 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
296 struct btrfs_disk_key key;
299 /* this is used for op == MOD_LOG_MOVE_KEYS */
305 /* this is used for op == MOD_LOG_ROOT_REPLACE */
306 struct tree_mod_root old_root;
310 * Pull a new tree mod seq number for our operation.
312 static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
314 return atomic64_inc_return(&fs_info->tree_mod_seq);
318 * This adds a new blocker to the tree mod log's blocker list if the @elem
319 * passed does not already have a sequence number set. So when a caller expects
320 * to record tree modifications, it should ensure to set elem->seq to zero
321 * before calling btrfs_get_tree_mod_seq.
322 * Returns a fresh, unused tree log modification sequence number, even if no new
325 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
326 struct seq_list *elem)
328 write_lock(&fs_info->tree_mod_log_lock);
329 spin_lock(&fs_info->tree_mod_seq_lock);
331 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
332 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
334 spin_unlock(&fs_info->tree_mod_seq_lock);
335 write_unlock(&fs_info->tree_mod_log_lock);
340 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
341 struct seq_list *elem)
343 struct rb_root *tm_root;
344 struct rb_node *node;
345 struct rb_node *next;
346 struct seq_list *cur_elem;
347 struct tree_mod_elem *tm;
348 u64 min_seq = (u64)-1;
349 u64 seq_putting = elem->seq;
354 spin_lock(&fs_info->tree_mod_seq_lock);
355 list_del(&elem->list);
358 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
359 if (cur_elem->seq < min_seq) {
360 if (seq_putting > cur_elem->seq) {
362 * blocker with lower sequence number exists, we
363 * cannot remove anything from the log
365 spin_unlock(&fs_info->tree_mod_seq_lock);
368 min_seq = cur_elem->seq;
371 spin_unlock(&fs_info->tree_mod_seq_lock);
374 * anything that's lower than the lowest existing (read: blocked)
375 * sequence number can be removed from the tree.
377 write_lock(&fs_info->tree_mod_log_lock);
378 tm_root = &fs_info->tree_mod_log;
379 for (node = rb_first(tm_root); node; node = next) {
380 next = rb_next(node);
381 tm = rb_entry(node, struct tree_mod_elem, node);
382 if (tm->seq > min_seq)
384 rb_erase(node, tm_root);
387 write_unlock(&fs_info->tree_mod_log_lock);
391 * key order of the log:
392 * node/leaf start address -> sequence
394 * The 'start address' is the logical address of the *new* root node
395 * for root replace operations, or the logical address of the affected
396 * block for all other operations.
399 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
401 struct rb_root *tm_root;
402 struct rb_node **new;
403 struct rb_node *parent = NULL;
404 struct tree_mod_elem *cur;
406 lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
408 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
410 tm_root = &fs_info->tree_mod_log;
411 new = &tm_root->rb_node;
413 cur = rb_entry(*new, struct tree_mod_elem, node);
415 if (cur->logical < tm->logical)
416 new = &((*new)->rb_left);
417 else if (cur->logical > tm->logical)
418 new = &((*new)->rb_right);
419 else if (cur->seq < tm->seq)
420 new = &((*new)->rb_left);
421 else if (cur->seq > tm->seq)
422 new = &((*new)->rb_right);
427 rb_link_node(&tm->node, parent, new);
428 rb_insert_color(&tm->node, tm_root);
433 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
434 * returns zero with the tree_mod_log_lock acquired. The caller must hold
435 * this until all tree mod log insertions are recorded in the rb tree and then
436 * write unlock fs_info::tree_mod_log_lock.
438 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
439 struct extent_buffer *eb) {
441 if (list_empty(&(fs_info)->tree_mod_seq_list))
443 if (eb && btrfs_header_level(eb) == 0)
446 write_lock(&fs_info->tree_mod_log_lock);
447 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
448 write_unlock(&fs_info->tree_mod_log_lock);
455 /* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
456 static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
457 struct extent_buffer *eb)
460 if (list_empty(&(fs_info)->tree_mod_seq_list))
462 if (eb && btrfs_header_level(eb) == 0)
468 static struct tree_mod_elem *
469 alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
470 enum mod_log_op op, gfp_t flags)
472 struct tree_mod_elem *tm;
474 tm = kzalloc(sizeof(*tm), flags);
478 tm->logical = eb->start;
479 if (op != MOD_LOG_KEY_ADD) {
480 btrfs_node_key(eb, &tm->key, slot);
481 tm->blockptr = btrfs_node_blockptr(eb, slot);
485 tm->generation = btrfs_node_ptr_generation(eb, slot);
486 RB_CLEAR_NODE(&tm->node);
491 static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
492 enum mod_log_op op, gfp_t flags)
494 struct tree_mod_elem *tm;
497 if (!tree_mod_need_log(eb->fs_info, eb))
500 tm = alloc_tree_mod_elem(eb, slot, op, flags);
504 if (tree_mod_dont_log(eb->fs_info, eb)) {
509 ret = __tree_mod_log_insert(eb->fs_info, tm);
510 write_unlock(&eb->fs_info->tree_mod_log_lock);
517 static noinline int tree_mod_log_insert_move(struct extent_buffer *eb,
518 int dst_slot, int src_slot, int nr_items)
520 struct tree_mod_elem *tm = NULL;
521 struct tree_mod_elem **tm_list = NULL;
526 if (!tree_mod_need_log(eb->fs_info, eb))
529 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
533 tm = kzalloc(sizeof(*tm), GFP_NOFS);
539 tm->logical = eb->start;
541 tm->move.dst_slot = dst_slot;
542 tm->move.nr_items = nr_items;
543 tm->op = MOD_LOG_MOVE_KEYS;
545 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
546 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
547 MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
554 if (tree_mod_dont_log(eb->fs_info, eb))
559 * When we override something during the move, we log these removals.
560 * This can only happen when we move towards the beginning of the
561 * buffer, i.e. dst_slot < src_slot.
563 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
564 ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]);
569 ret = __tree_mod_log_insert(eb->fs_info, tm);
572 write_unlock(&eb->fs_info->tree_mod_log_lock);
577 for (i = 0; i < nr_items; i++) {
578 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
579 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
583 write_unlock(&eb->fs_info->tree_mod_log_lock);
591 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
592 struct tree_mod_elem **tm_list,
598 for (i = nritems - 1; i >= 0; i--) {
599 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
601 for (j = nritems - 1; j > i; j--)
602 rb_erase(&tm_list[j]->node,
603 &fs_info->tree_mod_log);
611 static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root,
612 struct extent_buffer *new_root, int log_removal)
614 struct btrfs_fs_info *fs_info = old_root->fs_info;
615 struct tree_mod_elem *tm = NULL;
616 struct tree_mod_elem **tm_list = NULL;
621 if (!tree_mod_need_log(fs_info, NULL))
624 if (log_removal && btrfs_header_level(old_root) > 0) {
625 nritems = btrfs_header_nritems(old_root);
626 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
632 for (i = 0; i < nritems; i++) {
633 tm_list[i] = alloc_tree_mod_elem(old_root, i,
634 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
642 tm = kzalloc(sizeof(*tm), GFP_NOFS);
648 tm->logical = new_root->start;
649 tm->old_root.logical = old_root->start;
650 tm->old_root.level = btrfs_header_level(old_root);
651 tm->generation = btrfs_header_generation(old_root);
652 tm->op = MOD_LOG_ROOT_REPLACE;
654 if (tree_mod_dont_log(fs_info, NULL))
658 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
660 ret = __tree_mod_log_insert(fs_info, tm);
662 write_unlock(&fs_info->tree_mod_log_lock);
671 for (i = 0; i < nritems; i++)
680 static struct tree_mod_elem *
681 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
684 struct rb_root *tm_root;
685 struct rb_node *node;
686 struct tree_mod_elem *cur = NULL;
687 struct tree_mod_elem *found = NULL;
689 read_lock(&fs_info->tree_mod_log_lock);
690 tm_root = &fs_info->tree_mod_log;
691 node = tm_root->rb_node;
693 cur = rb_entry(node, struct tree_mod_elem, node);
694 if (cur->logical < start) {
695 node = node->rb_left;
696 } else if (cur->logical > start) {
697 node = node->rb_right;
698 } else if (cur->seq < min_seq) {
699 node = node->rb_left;
700 } else if (!smallest) {
701 /* we want the node with the highest seq */
703 BUG_ON(found->seq > cur->seq);
705 node = node->rb_left;
706 } else if (cur->seq > min_seq) {
707 /* we want the node with the smallest seq */
709 BUG_ON(found->seq < cur->seq);
711 node = node->rb_right;
717 read_unlock(&fs_info->tree_mod_log_lock);
723 * this returns the element from the log with the smallest time sequence
724 * value that's in the log (the oldest log item). any element with a time
725 * sequence lower than min_seq will be ignored.
727 static struct tree_mod_elem *
728 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
731 return __tree_mod_log_search(fs_info, start, min_seq, 1);
735 * this returns the element from the log with the largest time sequence
736 * value that's in the log (the most recent log item). any element with
737 * a time sequence lower than min_seq will be ignored.
739 static struct tree_mod_elem *
740 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
742 return __tree_mod_log_search(fs_info, start, min_seq, 0);
745 static noinline int tree_mod_log_eb_copy(struct extent_buffer *dst,
746 struct extent_buffer *src, unsigned long dst_offset,
747 unsigned long src_offset, int nr_items)
749 struct btrfs_fs_info *fs_info = dst->fs_info;
751 struct tree_mod_elem **tm_list = NULL;
752 struct tree_mod_elem **tm_list_add, **tm_list_rem;
756 if (!tree_mod_need_log(fs_info, NULL))
759 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
762 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
767 tm_list_add = tm_list;
768 tm_list_rem = tm_list + nr_items;
769 for (i = 0; i < nr_items; i++) {
770 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
771 MOD_LOG_KEY_REMOVE, GFP_NOFS);
772 if (!tm_list_rem[i]) {
777 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
778 MOD_LOG_KEY_ADD, GFP_NOFS);
779 if (!tm_list_add[i]) {
785 if (tree_mod_dont_log(fs_info, NULL))
789 for (i = 0; i < nr_items; i++) {
790 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
793 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
798 write_unlock(&fs_info->tree_mod_log_lock);
804 for (i = 0; i < nr_items * 2; i++) {
805 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
806 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
810 write_unlock(&fs_info->tree_mod_log_lock);
816 static noinline int tree_mod_log_free_eb(struct extent_buffer *eb)
818 struct tree_mod_elem **tm_list = NULL;
823 if (btrfs_header_level(eb) == 0)
826 if (!tree_mod_need_log(eb->fs_info, NULL))
829 nritems = btrfs_header_nritems(eb);
830 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
834 for (i = 0; i < nritems; i++) {
835 tm_list[i] = alloc_tree_mod_elem(eb, i,
836 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
843 if (tree_mod_dont_log(eb->fs_info, eb))
846 ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
847 write_unlock(&eb->fs_info->tree_mod_log_lock);
855 for (i = 0; i < nritems; i++)
863 * check if the tree block can be shared by multiple trees
865 int btrfs_block_can_be_shared(struct btrfs_root *root,
866 struct extent_buffer *buf)
869 * Tree blocks not in reference counted trees and tree roots
870 * are never shared. If a block was allocated after the last
871 * snapshot and the block was not allocated by tree relocation,
872 * we know the block is not shared.
874 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
875 buf != root->node && buf != root->commit_root &&
876 (btrfs_header_generation(buf) <=
877 btrfs_root_last_snapshot(&root->root_item) ||
878 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
884 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
885 struct btrfs_root *root,
886 struct extent_buffer *buf,
887 struct extent_buffer *cow,
890 struct btrfs_fs_info *fs_info = root->fs_info;
898 * Backrefs update rules:
900 * Always use full backrefs for extent pointers in tree block
901 * allocated by tree relocation.
903 * If a shared tree block is no longer referenced by its owner
904 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
905 * use full backrefs for extent pointers in tree block.
907 * If a tree block is been relocating
908 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
909 * use full backrefs for extent pointers in tree block.
910 * The reason for this is some operations (such as drop tree)
911 * are only allowed for blocks use full backrefs.
914 if (btrfs_block_can_be_shared(root, buf)) {
915 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
916 btrfs_header_level(buf), 1,
922 btrfs_handle_fs_error(fs_info, ret, NULL);
927 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
928 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
929 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
934 owner = btrfs_header_owner(buf);
935 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
936 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
939 if ((owner == root->root_key.objectid ||
940 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
941 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
942 ret = btrfs_inc_ref(trans, root, buf, 1);
946 if (root->root_key.objectid ==
947 BTRFS_TREE_RELOC_OBJECTID) {
948 ret = btrfs_dec_ref(trans, root, buf, 0);
951 ret = btrfs_inc_ref(trans, root, cow, 1);
955 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
958 if (root->root_key.objectid ==
959 BTRFS_TREE_RELOC_OBJECTID)
960 ret = btrfs_inc_ref(trans, root, cow, 1);
962 ret = btrfs_inc_ref(trans, root, cow, 0);
966 if (new_flags != 0) {
967 int level = btrfs_header_level(buf);
969 ret = btrfs_set_disk_extent_flags(trans,
972 new_flags, level, 0);
977 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
978 if (root->root_key.objectid ==
979 BTRFS_TREE_RELOC_OBJECTID)
980 ret = btrfs_inc_ref(trans, root, cow, 1);
982 ret = btrfs_inc_ref(trans, root, cow, 0);
985 ret = btrfs_dec_ref(trans, root, buf, 1);
989 btrfs_clean_tree_block(buf);
995 static struct extent_buffer *alloc_tree_block_no_bg_flush(
996 struct btrfs_trans_handle *trans,
997 struct btrfs_root *root,
999 const struct btrfs_disk_key *disk_key,
1004 struct btrfs_fs_info *fs_info = root->fs_info;
1005 struct extent_buffer *ret;
1008 * If we are COWing a node/leaf from the extent, chunk, device or free
1009 * space trees, make sure that we do not finish block group creation of
1010 * pending block groups. We do this to avoid a deadlock.
1011 * COWing can result in allocation of a new chunk, and flushing pending
1012 * block groups (btrfs_create_pending_block_groups()) can be triggered
1013 * when finishing allocation of a new chunk. Creation of a pending block
1014 * group modifies the extent, chunk, device and free space trees,
1015 * therefore we could deadlock with ourselves since we are holding a
1016 * lock on an extent buffer that btrfs_create_pending_block_groups() may
1018 * For similar reasons, we also need to delay flushing pending block
1019 * groups when splitting a leaf or node, from one of those trees, since
1020 * we are holding a write lock on it and its parent or when inserting a
1021 * new root node for one of those trees.
1023 if (root == fs_info->extent_root ||
1024 root == fs_info->chunk_root ||
1025 root == fs_info->dev_root ||
1026 root == fs_info->free_space_root)
1027 trans->can_flush_pending_bgs = false;
1029 ret = btrfs_alloc_tree_block(trans, root, parent_start,
1030 root->root_key.objectid, disk_key, level,
1032 trans->can_flush_pending_bgs = true;
1038 * does the dirty work in cow of a single block. The parent block (if
1039 * supplied) is updated to point to the new cow copy. The new buffer is marked
1040 * dirty and returned locked. If you modify the block it needs to be marked
1043 * search_start -- an allocation hint for the new block
1045 * empty_size -- a hint that you plan on doing more cow. This is the size in
1046 * bytes the allocator should try to find free next to the block it returns.
1047 * This is just a hint and may be ignored by the allocator.
1049 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1050 struct btrfs_root *root,
1051 struct extent_buffer *buf,
1052 struct extent_buffer *parent, int parent_slot,
1053 struct extent_buffer **cow_ret,
1054 u64 search_start, u64 empty_size)
1056 struct btrfs_fs_info *fs_info = root->fs_info;
1057 struct btrfs_disk_key disk_key;
1058 struct extent_buffer *cow;
1061 int unlock_orig = 0;
1062 u64 parent_start = 0;
1064 if (*cow_ret == buf)
1067 btrfs_assert_tree_locked(buf);
1069 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1070 trans->transid != fs_info->running_transaction->transid);
1071 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1072 trans->transid != root->last_trans);
1074 level = btrfs_header_level(buf);
1077 btrfs_item_key(buf, &disk_key, 0);
1079 btrfs_node_key(buf, &disk_key, 0);
1081 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1082 parent_start = parent->start;
1084 cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
1085 level, search_start, empty_size);
1087 return PTR_ERR(cow);
1089 /* cow is set to blocking by btrfs_init_new_buffer */
1091 copy_extent_buffer_full(cow, buf);
1092 btrfs_set_header_bytenr(cow, cow->start);
1093 btrfs_set_header_generation(cow, trans->transid);
1094 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1095 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1096 BTRFS_HEADER_FLAG_RELOC);
1097 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1098 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1100 btrfs_set_header_owner(cow, root->root_key.objectid);
1102 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
1104 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1106 btrfs_abort_transaction(trans, ret);
1110 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
1111 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1113 btrfs_abort_transaction(trans, ret);
1118 if (buf == root->node) {
1119 WARN_ON(parent && parent != buf);
1120 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1121 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1122 parent_start = buf->start;
1124 atomic_inc(&cow->refs);
1125 ret = tree_mod_log_insert_root(root->node, cow, 1);
1127 rcu_assign_pointer(root->node, cow);
1129 btrfs_free_tree_block(trans, root, buf, parent_start,
1131 free_extent_buffer(buf);
1132 add_root_to_dirty_list(root);
1134 WARN_ON(trans->transid != btrfs_header_generation(parent));
1135 tree_mod_log_insert_key(parent, parent_slot,
1136 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1137 btrfs_set_node_blockptr(parent, parent_slot,
1139 btrfs_set_node_ptr_generation(parent, parent_slot,
1141 btrfs_mark_buffer_dirty(parent);
1143 ret = tree_mod_log_free_eb(buf);
1145 btrfs_abort_transaction(trans, ret);
1149 btrfs_free_tree_block(trans, root, buf, parent_start,
1153 btrfs_tree_unlock(buf);
1154 free_extent_buffer_stale(buf);
1155 btrfs_mark_buffer_dirty(cow);
1161 * returns the logical address of the oldest predecessor of the given root.
1162 * entries older than time_seq are ignored.
1164 static struct tree_mod_elem *__tree_mod_log_oldest_root(
1165 struct extent_buffer *eb_root, u64 time_seq)
1167 struct tree_mod_elem *tm;
1168 struct tree_mod_elem *found = NULL;
1169 u64 root_logical = eb_root->start;
1176 * the very last operation that's logged for a root is the
1177 * replacement operation (if it is replaced at all). this has
1178 * the logical address of the *new* root, making it the very
1179 * first operation that's logged for this root.
1182 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
1187 * if there are no tree operation for the oldest root, we simply
1188 * return it. this should only happen if that (old) root is at
1195 * if there's an operation that's not a root replacement, we
1196 * found the oldest version of our root. normally, we'll find a
1197 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1199 if (tm->op != MOD_LOG_ROOT_REPLACE)
1203 root_logical = tm->old_root.logical;
1207 /* if there's no old root to return, return what we found instead */
1215 * tm is a pointer to the first operation to rewind within eb. then, all
1216 * previous operations will be rewound (until we reach something older than
1220 __tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1221 u64 time_seq, struct tree_mod_elem *first_tm)
1224 struct rb_node *next;
1225 struct tree_mod_elem *tm = first_tm;
1226 unsigned long o_dst;
1227 unsigned long o_src;
1228 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1230 n = btrfs_header_nritems(eb);
1231 read_lock(&fs_info->tree_mod_log_lock);
1232 while (tm && tm->seq >= time_seq) {
1234 * all the operations are recorded with the operator used for
1235 * the modification. as we're going backwards, we do the
1236 * opposite of each operation here.
1239 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1240 BUG_ON(tm->slot < n);
1242 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1243 case MOD_LOG_KEY_REMOVE:
1244 btrfs_set_node_key(eb, &tm->key, tm->slot);
1245 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1246 btrfs_set_node_ptr_generation(eb, tm->slot,
1250 case MOD_LOG_KEY_REPLACE:
1251 BUG_ON(tm->slot >= n);
1252 btrfs_set_node_key(eb, &tm->key, tm->slot);
1253 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1254 btrfs_set_node_ptr_generation(eb, tm->slot,
1257 case MOD_LOG_KEY_ADD:
1258 /* if a move operation is needed it's in the log */
1261 case MOD_LOG_MOVE_KEYS:
1262 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1263 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1264 memmove_extent_buffer(eb, o_dst, o_src,
1265 tm->move.nr_items * p_size);
1267 case MOD_LOG_ROOT_REPLACE:
1269 * this operation is special. for roots, this must be
1270 * handled explicitly before rewinding.
1271 * for non-roots, this operation may exist if the node
1272 * was a root: root A -> child B; then A gets empty and
1273 * B is promoted to the new root. in the mod log, we'll
1274 * have a root-replace operation for B, a tree block
1275 * that is no root. we simply ignore that operation.
1279 next = rb_next(&tm->node);
1282 tm = rb_entry(next, struct tree_mod_elem, node);
1283 if (tm->logical != first_tm->logical)
1286 read_unlock(&fs_info->tree_mod_log_lock);
1287 btrfs_set_header_nritems(eb, n);
1291 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1292 * is returned. If rewind operations happen, a fresh buffer is returned. The
1293 * returned buffer is always read-locked. If the returned buffer is not the
1294 * input buffer, the lock on the input buffer is released and the input buffer
1295 * is freed (its refcount is decremented).
1297 static struct extent_buffer *
1298 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1299 struct extent_buffer *eb, u64 time_seq)
1301 struct extent_buffer *eb_rewin;
1302 struct tree_mod_elem *tm;
1307 if (btrfs_header_level(eb) == 0)
1310 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1314 btrfs_set_path_blocking(path);
1315 btrfs_set_lock_blocking_read(eb);
1317 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1318 BUG_ON(tm->slot != 0);
1319 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1321 btrfs_tree_read_unlock_blocking(eb);
1322 free_extent_buffer(eb);
1325 btrfs_set_header_bytenr(eb_rewin, eb->start);
1326 btrfs_set_header_backref_rev(eb_rewin,
1327 btrfs_header_backref_rev(eb));
1328 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1329 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1331 eb_rewin = btrfs_clone_extent_buffer(eb);
1333 btrfs_tree_read_unlock_blocking(eb);
1334 free_extent_buffer(eb);
1339 btrfs_tree_read_unlock_blocking(eb);
1340 free_extent_buffer(eb);
1342 btrfs_tree_read_lock(eb_rewin);
1343 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1344 WARN_ON(btrfs_header_nritems(eb_rewin) >
1345 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1351 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1352 * value. If there are no changes, the current root->root_node is returned. If
1353 * anything changed in between, there's a fresh buffer allocated on which the
1354 * rewind operations are done. In any case, the returned buffer is read locked.
1355 * Returns NULL on error (with no locks held).
1357 static inline struct extent_buffer *
1358 get_old_root(struct btrfs_root *root, u64 time_seq)
1360 struct btrfs_fs_info *fs_info = root->fs_info;
1361 struct tree_mod_elem *tm;
1362 struct extent_buffer *eb = NULL;
1363 struct extent_buffer *eb_root;
1364 u64 eb_root_owner = 0;
1365 struct extent_buffer *old;
1366 struct tree_mod_root *old_root = NULL;
1367 u64 old_generation = 0;
1371 eb_root = btrfs_read_lock_root_node(root);
1372 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1376 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1377 old_root = &tm->old_root;
1378 old_generation = tm->generation;
1379 logical = old_root->logical;
1380 level = old_root->level;
1382 logical = eb_root->start;
1383 level = btrfs_header_level(eb_root);
1386 tm = tree_mod_log_search(fs_info, logical, time_seq);
1387 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1388 btrfs_tree_read_unlock(eb_root);
1389 free_extent_buffer(eb_root);
1390 old = read_tree_block(fs_info, logical, 0, level, NULL);
1391 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1393 free_extent_buffer(old);
1395 "failed to read tree block %llu from get_old_root",
1398 eb = btrfs_clone_extent_buffer(old);
1399 free_extent_buffer(old);
1401 } else if (old_root) {
1402 eb_root_owner = btrfs_header_owner(eb_root);
1403 btrfs_tree_read_unlock(eb_root);
1404 free_extent_buffer(eb_root);
1405 eb = alloc_dummy_extent_buffer(fs_info, logical);
1407 btrfs_set_lock_blocking_read(eb_root);
1408 eb = btrfs_clone_extent_buffer(eb_root);
1409 btrfs_tree_read_unlock_blocking(eb_root);
1410 free_extent_buffer(eb_root);
1415 btrfs_tree_read_lock(eb);
1417 btrfs_set_header_bytenr(eb, eb->start);
1418 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1419 btrfs_set_header_owner(eb, eb_root_owner);
1420 btrfs_set_header_level(eb, old_root->level);
1421 btrfs_set_header_generation(eb, old_generation);
1424 __tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1426 WARN_ON(btrfs_header_level(eb) != 0);
1427 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1432 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1434 struct tree_mod_elem *tm;
1436 struct extent_buffer *eb_root = btrfs_root_node(root);
1438 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1439 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1440 level = tm->old_root.level;
1442 level = btrfs_header_level(eb_root);
1444 free_extent_buffer(eb_root);
1449 static inline int should_cow_block(struct btrfs_trans_handle *trans,
1450 struct btrfs_root *root,
1451 struct extent_buffer *buf)
1453 if (btrfs_is_testing(root->fs_info))
1456 /* Ensure we can see the FORCE_COW bit */
1457 smp_mb__before_atomic();
1460 * We do not need to cow a block if
1461 * 1) this block is not created or changed in this transaction;
1462 * 2) this block does not belong to TREE_RELOC tree;
1463 * 3) the root is not forced COW.
1465 * What is forced COW:
1466 * when we create snapshot during committing the transaction,
1467 * after we've finished copying src root, we must COW the shared
1468 * block to ensure the metadata consistency.
1470 if (btrfs_header_generation(buf) == trans->transid &&
1471 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1472 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1473 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1474 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1480 * cows a single block, see __btrfs_cow_block for the real work.
1481 * This version of it has extra checks so that a block isn't COWed more than
1482 * once per transaction, as long as it hasn't been written yet
1484 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1485 struct btrfs_root *root, struct extent_buffer *buf,
1486 struct extent_buffer *parent, int parent_slot,
1487 struct extent_buffer **cow_ret)
1489 struct btrfs_fs_info *fs_info = root->fs_info;
1493 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
1495 "COW'ing blocks on a fs root that's being dropped");
1497 if (trans->transaction != fs_info->running_transaction)
1498 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1500 fs_info->running_transaction->transid);
1502 if (trans->transid != fs_info->generation)
1503 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1504 trans->transid, fs_info->generation);
1506 if (!should_cow_block(trans, root, buf)) {
1507 trans->dirty = true;
1512 search_start = buf->start & ~((u64)SZ_1G - 1);
1515 btrfs_set_lock_blocking_write(parent);
1516 btrfs_set_lock_blocking_write(buf);
1519 * Before CoWing this block for later modification, check if it's
1520 * the subtree root and do the delayed subtree trace if needed.
1522 * Also We don't care about the error, as it's handled internally.
1524 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
1525 ret = __btrfs_cow_block(trans, root, buf, parent,
1526 parent_slot, cow_ret, search_start, 0);
1528 trace_btrfs_cow_block(root, buf, *cow_ret);
1534 * helper function for defrag to decide if two blocks pointed to by a
1535 * node are actually close by
1537 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1539 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1541 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1547 * compare two keys in a memcmp fashion
1549 static int comp_keys(const struct btrfs_disk_key *disk,
1550 const struct btrfs_key *k2)
1552 struct btrfs_key k1;
1554 btrfs_disk_key_to_cpu(&k1, disk);
1556 return btrfs_comp_cpu_keys(&k1, k2);
1560 * same as comp_keys only with two btrfs_key's
1562 int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1564 if (k1->objectid > k2->objectid)
1566 if (k1->objectid < k2->objectid)
1568 if (k1->type > k2->type)
1570 if (k1->type < k2->type)
1572 if (k1->offset > k2->offset)
1574 if (k1->offset < k2->offset)
1580 * this is used by the defrag code to go through all the
1581 * leaves pointed to by a node and reallocate them so that
1582 * disk order is close to key order
1584 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1585 struct btrfs_root *root, struct extent_buffer *parent,
1586 int start_slot, u64 *last_ret,
1587 struct btrfs_key *progress)
1589 struct btrfs_fs_info *fs_info = root->fs_info;
1590 struct extent_buffer *cur;
1593 u64 search_start = *last_ret;
1603 int progress_passed = 0;
1604 struct btrfs_disk_key disk_key;
1606 parent_level = btrfs_header_level(parent);
1608 WARN_ON(trans->transaction != fs_info->running_transaction);
1609 WARN_ON(trans->transid != fs_info->generation);
1611 parent_nritems = btrfs_header_nritems(parent);
1612 blocksize = fs_info->nodesize;
1613 end_slot = parent_nritems - 1;
1615 if (parent_nritems <= 1)
1618 btrfs_set_lock_blocking_write(parent);
1620 for (i = start_slot; i <= end_slot; i++) {
1621 struct btrfs_key first_key;
1624 btrfs_node_key(parent, &disk_key, i);
1625 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1628 progress_passed = 1;
1629 blocknr = btrfs_node_blockptr(parent, i);
1630 gen = btrfs_node_ptr_generation(parent, i);
1631 btrfs_node_key_to_cpu(parent, &first_key, i);
1632 if (last_block == 0)
1633 last_block = blocknr;
1636 other = btrfs_node_blockptr(parent, i - 1);
1637 close = close_blocks(blocknr, other, blocksize);
1639 if (!close && i < end_slot) {
1640 other = btrfs_node_blockptr(parent, i + 1);
1641 close = close_blocks(blocknr, other, blocksize);
1644 last_block = blocknr;
1648 cur = find_extent_buffer(fs_info, blocknr);
1650 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1653 if (!cur || !uptodate) {
1655 cur = read_tree_block(fs_info, blocknr, gen,
1659 return PTR_ERR(cur);
1660 } else if (!extent_buffer_uptodate(cur)) {
1661 free_extent_buffer(cur);
1664 } else if (!uptodate) {
1665 err = btrfs_read_buffer(cur, gen,
1666 parent_level - 1,&first_key);
1668 free_extent_buffer(cur);
1673 if (search_start == 0)
1674 search_start = last_block;
1676 btrfs_tree_lock(cur);
1677 btrfs_set_lock_blocking_write(cur);
1678 err = __btrfs_cow_block(trans, root, cur, parent, i,
1681 (end_slot - i) * blocksize));
1683 btrfs_tree_unlock(cur);
1684 free_extent_buffer(cur);
1687 search_start = cur->start;
1688 last_block = cur->start;
1689 *last_ret = search_start;
1690 btrfs_tree_unlock(cur);
1691 free_extent_buffer(cur);
1697 * search for key in the extent_buffer. The items start at offset p,
1698 * and they are item_size apart. There are 'max' items in p.
1700 * the slot in the array is returned via slot, and it points to
1701 * the place where you would insert key if it is not found in
1704 * slot may point to max if the key is bigger than all of the keys
1706 static noinline int generic_bin_search(struct extent_buffer *eb,
1707 unsigned long p, int item_size,
1708 const struct btrfs_key *key,
1715 struct btrfs_disk_key *tmp = NULL;
1716 struct btrfs_disk_key unaligned;
1717 unsigned long offset;
1719 unsigned long map_start = 0;
1720 unsigned long map_len = 0;
1724 btrfs_err(eb->fs_info,
1725 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1726 __func__, low, high, eb->start,
1727 btrfs_header_owner(eb), btrfs_header_level(eb));
1731 while (low < high) {
1732 mid = (low + high) / 2;
1733 offset = p + mid * item_size;
1735 if (!kaddr || offset < map_start ||
1736 (offset + sizeof(struct btrfs_disk_key)) >
1737 map_start + map_len) {
1739 err = map_private_extent_buffer(eb, offset,
1740 sizeof(struct btrfs_disk_key),
1741 &kaddr, &map_start, &map_len);
1744 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1746 } else if (err == 1) {
1747 read_extent_buffer(eb, &unaligned,
1748 offset, sizeof(unaligned));
1755 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1758 ret = comp_keys(tmp, key);
1774 * simple bin_search frontend that does the right thing for
1777 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1778 int level, int *slot)
1781 return generic_bin_search(eb,
1782 offsetof(struct btrfs_leaf, items),
1783 sizeof(struct btrfs_item),
1784 key, btrfs_header_nritems(eb),
1787 return generic_bin_search(eb,
1788 offsetof(struct btrfs_node, ptrs),
1789 sizeof(struct btrfs_key_ptr),
1790 key, btrfs_header_nritems(eb),
1794 static void root_add_used(struct btrfs_root *root, u32 size)
1796 spin_lock(&root->accounting_lock);
1797 btrfs_set_root_used(&root->root_item,
1798 btrfs_root_used(&root->root_item) + size);
1799 spin_unlock(&root->accounting_lock);
1802 static void root_sub_used(struct btrfs_root *root, u32 size)
1804 spin_lock(&root->accounting_lock);
1805 btrfs_set_root_used(&root->root_item,
1806 btrfs_root_used(&root->root_item) - size);
1807 spin_unlock(&root->accounting_lock);
1810 /* given a node and slot number, this reads the blocks it points to. The
1811 * extent buffer is returned with a reference taken (but unlocked).
1813 struct extent_buffer *btrfs_read_node_slot(struct extent_buffer *parent,
1816 int level = btrfs_header_level(parent);
1817 struct extent_buffer *eb;
1818 struct btrfs_key first_key;
1820 if (slot < 0 || slot >= btrfs_header_nritems(parent))
1821 return ERR_PTR(-ENOENT);
1825 btrfs_node_key_to_cpu(parent, &first_key, slot);
1826 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
1827 btrfs_node_ptr_generation(parent, slot),
1828 level - 1, &first_key);
1829 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1830 free_extent_buffer(eb);
1838 * node level balancing, used to make sure nodes are in proper order for
1839 * item deletion. We balance from the top down, so we have to make sure
1840 * that a deletion won't leave an node completely empty later on.
1842 static noinline int balance_level(struct btrfs_trans_handle *trans,
1843 struct btrfs_root *root,
1844 struct btrfs_path *path, int level)
1846 struct btrfs_fs_info *fs_info = root->fs_info;
1847 struct extent_buffer *right = NULL;
1848 struct extent_buffer *mid;
1849 struct extent_buffer *left = NULL;
1850 struct extent_buffer *parent = NULL;
1854 int orig_slot = path->slots[level];
1859 mid = path->nodes[level];
1861 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1862 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1863 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1865 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1867 if (level < BTRFS_MAX_LEVEL - 1) {
1868 parent = path->nodes[level + 1];
1869 pslot = path->slots[level + 1];
1873 * deal with the case where there is only one pointer in the root
1874 * by promoting the node below to a root
1877 struct extent_buffer *child;
1879 if (btrfs_header_nritems(mid) != 1)
1882 /* promote the child to a root */
1883 child = btrfs_read_node_slot(mid, 0);
1884 if (IS_ERR(child)) {
1885 ret = PTR_ERR(child);
1886 btrfs_handle_fs_error(fs_info, ret, NULL);
1890 btrfs_tree_lock(child);
1891 btrfs_set_lock_blocking_write(child);
1892 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1894 btrfs_tree_unlock(child);
1895 free_extent_buffer(child);
1899 ret = tree_mod_log_insert_root(root->node, child, 1);
1901 rcu_assign_pointer(root->node, child);
1903 add_root_to_dirty_list(root);
1904 btrfs_tree_unlock(child);
1906 path->locks[level] = 0;
1907 path->nodes[level] = NULL;
1908 btrfs_clean_tree_block(mid);
1909 btrfs_tree_unlock(mid);
1910 /* once for the path */
1911 free_extent_buffer(mid);
1913 root_sub_used(root, mid->len);
1914 btrfs_free_tree_block(trans, root, mid, 0, 1);
1915 /* once for the root ptr */
1916 free_extent_buffer_stale(mid);
1919 if (btrfs_header_nritems(mid) >
1920 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1923 left = btrfs_read_node_slot(parent, pslot - 1);
1928 btrfs_tree_lock(left);
1929 btrfs_set_lock_blocking_write(left);
1930 wret = btrfs_cow_block(trans, root, left,
1931 parent, pslot - 1, &left);
1938 right = btrfs_read_node_slot(parent, pslot + 1);
1943 btrfs_tree_lock(right);
1944 btrfs_set_lock_blocking_write(right);
1945 wret = btrfs_cow_block(trans, root, right,
1946 parent, pslot + 1, &right);
1953 /* first, try to make some room in the middle buffer */
1955 orig_slot += btrfs_header_nritems(left);
1956 wret = push_node_left(trans, left, mid, 1);
1962 * then try to empty the right most buffer into the middle
1965 wret = push_node_left(trans, mid, right, 1);
1966 if (wret < 0 && wret != -ENOSPC)
1968 if (btrfs_header_nritems(right) == 0) {
1969 btrfs_clean_tree_block(right);
1970 btrfs_tree_unlock(right);
1971 del_ptr(root, path, level + 1, pslot + 1);
1972 root_sub_used(root, right->len);
1973 btrfs_free_tree_block(trans, root, right, 0, 1);
1974 free_extent_buffer_stale(right);
1977 struct btrfs_disk_key right_key;
1978 btrfs_node_key(right, &right_key, 0);
1979 ret = tree_mod_log_insert_key(parent, pslot + 1,
1980 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1982 btrfs_set_node_key(parent, &right_key, pslot + 1);
1983 btrfs_mark_buffer_dirty(parent);
1986 if (btrfs_header_nritems(mid) == 1) {
1988 * we're not allowed to leave a node with one item in the
1989 * tree during a delete. A deletion from lower in the tree
1990 * could try to delete the only pointer in this node.
1991 * So, pull some keys from the left.
1992 * There has to be a left pointer at this point because
1993 * otherwise we would have pulled some pointers from the
1998 btrfs_handle_fs_error(fs_info, ret, NULL);
2001 wret = balance_node_right(trans, mid, left);
2007 wret = push_node_left(trans, left, mid, 1);
2013 if (btrfs_header_nritems(mid) == 0) {
2014 btrfs_clean_tree_block(mid);
2015 btrfs_tree_unlock(mid);
2016 del_ptr(root, path, level + 1, pslot);
2017 root_sub_used(root, mid->len);
2018 btrfs_free_tree_block(trans, root, mid, 0, 1);
2019 free_extent_buffer_stale(mid);
2022 /* update the parent key to reflect our changes */
2023 struct btrfs_disk_key mid_key;
2024 btrfs_node_key(mid, &mid_key, 0);
2025 ret = tree_mod_log_insert_key(parent, pslot,
2026 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2028 btrfs_set_node_key(parent, &mid_key, pslot);
2029 btrfs_mark_buffer_dirty(parent);
2032 /* update the path */
2034 if (btrfs_header_nritems(left) > orig_slot) {
2035 atomic_inc(&left->refs);
2036 /* left was locked after cow */
2037 path->nodes[level] = left;
2038 path->slots[level + 1] -= 1;
2039 path->slots[level] = orig_slot;
2041 btrfs_tree_unlock(mid);
2042 free_extent_buffer(mid);
2045 orig_slot -= btrfs_header_nritems(left);
2046 path->slots[level] = orig_slot;
2049 /* double check we haven't messed things up */
2051 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2055 btrfs_tree_unlock(right);
2056 free_extent_buffer(right);
2059 if (path->nodes[level] != left)
2060 btrfs_tree_unlock(left);
2061 free_extent_buffer(left);
2066 /* Node balancing for insertion. Here we only split or push nodes around
2067 * when they are completely full. This is also done top down, so we
2068 * have to be pessimistic.
2070 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2071 struct btrfs_root *root,
2072 struct btrfs_path *path, int level)
2074 struct btrfs_fs_info *fs_info = root->fs_info;
2075 struct extent_buffer *right = NULL;
2076 struct extent_buffer *mid;
2077 struct extent_buffer *left = NULL;
2078 struct extent_buffer *parent = NULL;
2082 int orig_slot = path->slots[level];
2087 mid = path->nodes[level];
2088 WARN_ON(btrfs_header_generation(mid) != trans->transid);
2090 if (level < BTRFS_MAX_LEVEL - 1) {
2091 parent = path->nodes[level + 1];
2092 pslot = path->slots[level + 1];
2098 left = btrfs_read_node_slot(parent, pslot - 1);
2102 /* first, try to make some room in the middle buffer */
2106 btrfs_tree_lock(left);
2107 btrfs_set_lock_blocking_write(left);
2109 left_nr = btrfs_header_nritems(left);
2110 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2113 ret = btrfs_cow_block(trans, root, left, parent,
2118 wret = push_node_left(trans, left, mid, 0);
2124 struct btrfs_disk_key disk_key;
2125 orig_slot += left_nr;
2126 btrfs_node_key(mid, &disk_key, 0);
2127 ret = tree_mod_log_insert_key(parent, pslot,
2128 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2130 btrfs_set_node_key(parent, &disk_key, pslot);
2131 btrfs_mark_buffer_dirty(parent);
2132 if (btrfs_header_nritems(left) > orig_slot) {
2133 path->nodes[level] = left;
2134 path->slots[level + 1] -= 1;
2135 path->slots[level] = orig_slot;
2136 btrfs_tree_unlock(mid);
2137 free_extent_buffer(mid);
2140 btrfs_header_nritems(left);
2141 path->slots[level] = orig_slot;
2142 btrfs_tree_unlock(left);
2143 free_extent_buffer(left);
2147 btrfs_tree_unlock(left);
2148 free_extent_buffer(left);
2150 right = btrfs_read_node_slot(parent, pslot + 1);
2155 * then try to empty the right most buffer into the middle
2160 btrfs_tree_lock(right);
2161 btrfs_set_lock_blocking_write(right);
2163 right_nr = btrfs_header_nritems(right);
2164 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2167 ret = btrfs_cow_block(trans, root, right,
2173 wret = balance_node_right(trans, right, mid);
2179 struct btrfs_disk_key disk_key;
2181 btrfs_node_key(right, &disk_key, 0);
2182 ret = tree_mod_log_insert_key(parent, pslot + 1,
2183 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2185 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2186 btrfs_mark_buffer_dirty(parent);
2188 if (btrfs_header_nritems(mid) <= orig_slot) {
2189 path->nodes[level] = right;
2190 path->slots[level + 1] += 1;
2191 path->slots[level] = orig_slot -
2192 btrfs_header_nritems(mid);
2193 btrfs_tree_unlock(mid);
2194 free_extent_buffer(mid);
2196 btrfs_tree_unlock(right);
2197 free_extent_buffer(right);
2201 btrfs_tree_unlock(right);
2202 free_extent_buffer(right);
2208 * readahead one full node of leaves, finding things that are close
2209 * to the block in 'slot', and triggering ra on them.
2211 static void reada_for_search(struct btrfs_fs_info *fs_info,
2212 struct btrfs_path *path,
2213 int level, int slot, u64 objectid)
2215 struct extent_buffer *node;
2216 struct btrfs_disk_key disk_key;
2221 struct extent_buffer *eb;
2229 if (!path->nodes[level])
2232 node = path->nodes[level];
2234 search = btrfs_node_blockptr(node, slot);
2235 blocksize = fs_info->nodesize;
2236 eb = find_extent_buffer(fs_info, search);
2238 free_extent_buffer(eb);
2244 nritems = btrfs_header_nritems(node);
2248 if (path->reada == READA_BACK) {
2252 } else if (path->reada == READA_FORWARD) {
2257 if (path->reada == READA_BACK && objectid) {
2258 btrfs_node_key(node, &disk_key, nr);
2259 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2262 search = btrfs_node_blockptr(node, nr);
2263 if ((search <= target && target - search <= 65536) ||
2264 (search > target && search - target <= 65536)) {
2265 readahead_tree_block(fs_info, search);
2269 if ((nread > 65536 || nscan > 32))
2274 static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2275 struct btrfs_path *path, int level)
2279 struct extent_buffer *parent;
2280 struct extent_buffer *eb;
2285 parent = path->nodes[level + 1];
2289 nritems = btrfs_header_nritems(parent);
2290 slot = path->slots[level + 1];
2293 block1 = btrfs_node_blockptr(parent, slot - 1);
2294 gen = btrfs_node_ptr_generation(parent, slot - 1);
2295 eb = find_extent_buffer(fs_info, block1);
2297 * if we get -eagain from btrfs_buffer_uptodate, we
2298 * don't want to return eagain here. That will loop
2301 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2303 free_extent_buffer(eb);
2305 if (slot + 1 < nritems) {
2306 block2 = btrfs_node_blockptr(parent, slot + 1);
2307 gen = btrfs_node_ptr_generation(parent, slot + 1);
2308 eb = find_extent_buffer(fs_info, block2);
2309 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2311 free_extent_buffer(eb);
2315 readahead_tree_block(fs_info, block1);
2317 readahead_tree_block(fs_info, block2);
2322 * when we walk down the tree, it is usually safe to unlock the higher layers
2323 * in the tree. The exceptions are when our path goes through slot 0, because
2324 * operations on the tree might require changing key pointers higher up in the
2327 * callers might also have set path->keep_locks, which tells this code to keep
2328 * the lock if the path points to the last slot in the block. This is part of
2329 * walking through the tree, and selecting the next slot in the higher block.
2331 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2332 * if lowest_unlock is 1, level 0 won't be unlocked
2334 static noinline void unlock_up(struct btrfs_path *path, int level,
2335 int lowest_unlock, int min_write_lock_level,
2336 int *write_lock_level)
2339 int skip_level = level;
2341 struct extent_buffer *t;
2343 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2344 if (!path->nodes[i])
2346 if (!path->locks[i])
2348 if (!no_skips && path->slots[i] == 0) {
2352 if (!no_skips && path->keep_locks) {
2355 nritems = btrfs_header_nritems(t);
2356 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2361 if (skip_level < i && i >= lowest_unlock)
2365 if (i >= lowest_unlock && i > skip_level) {
2366 btrfs_tree_unlock_rw(t, path->locks[i]);
2368 if (write_lock_level &&
2369 i > min_write_lock_level &&
2370 i <= *write_lock_level) {
2371 *write_lock_level = i - 1;
2378 * helper function for btrfs_search_slot. The goal is to find a block
2379 * in cache without setting the path to blocking. If we find the block
2380 * we return zero and the path is unchanged.
2382 * If we can't find the block, we set the path blocking and do some
2383 * reada. -EAGAIN is returned and the search must be repeated.
2386 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2387 struct extent_buffer **eb_ret, int level, int slot,
2388 const struct btrfs_key *key)
2390 struct btrfs_fs_info *fs_info = root->fs_info;
2393 struct extent_buffer *b = *eb_ret;
2394 struct extent_buffer *tmp;
2395 struct btrfs_key first_key;
2399 blocknr = btrfs_node_blockptr(b, slot);
2400 gen = btrfs_node_ptr_generation(b, slot);
2401 parent_level = btrfs_header_level(b);
2402 btrfs_node_key_to_cpu(b, &first_key, slot);
2404 tmp = find_extent_buffer(fs_info, blocknr);
2406 /* first we do an atomic uptodate check */
2407 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2409 * Do extra check for first_key, eb can be stale due to
2410 * being cached, read from scrub, or have multiple
2411 * parents (shared tree blocks).
2413 if (btrfs_verify_level_key(tmp,
2414 parent_level - 1, &first_key, gen)) {
2415 free_extent_buffer(tmp);
2422 /* the pages were up to date, but we failed
2423 * the generation number check. Do a full
2424 * read for the generation number that is correct.
2425 * We must do this without dropping locks so
2426 * we can trust our generation number
2428 btrfs_set_path_blocking(p);
2430 /* now we're allowed to do a blocking uptodate check */
2431 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
2436 free_extent_buffer(tmp);
2437 btrfs_release_path(p);
2442 * reduce lock contention at high levels
2443 * of the btree by dropping locks before
2444 * we read. Don't release the lock on the current
2445 * level because we need to walk this node to figure
2446 * out which blocks to read.
2448 btrfs_unlock_up_safe(p, level + 1);
2449 btrfs_set_path_blocking(p);
2451 if (p->reada != READA_NONE)
2452 reada_for_search(fs_info, p, level, slot, key->objectid);
2455 tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
2459 * If the read above didn't mark this buffer up to date,
2460 * it will never end up being up to date. Set ret to EIO now
2461 * and give up so that our caller doesn't loop forever
2464 if (!extent_buffer_uptodate(tmp))
2466 free_extent_buffer(tmp);
2471 btrfs_release_path(p);
2476 * helper function for btrfs_search_slot. This does all of the checks
2477 * for node-level blocks and does any balancing required based on
2480 * If no extra work was required, zero is returned. If we had to
2481 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2485 setup_nodes_for_search(struct btrfs_trans_handle *trans,
2486 struct btrfs_root *root, struct btrfs_path *p,
2487 struct extent_buffer *b, int level, int ins_len,
2488 int *write_lock_level)
2490 struct btrfs_fs_info *fs_info = root->fs_info;
2493 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2494 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2497 if (*write_lock_level < level + 1) {
2498 *write_lock_level = level + 1;
2499 btrfs_release_path(p);
2503 btrfs_set_path_blocking(p);
2504 reada_for_balance(fs_info, p, level);
2505 sret = split_node(trans, root, p, level);
2512 b = p->nodes[level];
2513 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2514 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2517 if (*write_lock_level < level + 1) {
2518 *write_lock_level = level + 1;
2519 btrfs_release_path(p);
2523 btrfs_set_path_blocking(p);
2524 reada_for_balance(fs_info, p, level);
2525 sret = balance_level(trans, root, p, level);
2531 b = p->nodes[level];
2533 btrfs_release_path(p);
2536 BUG_ON(btrfs_header_nritems(b) == 1);
2546 static int key_search(struct extent_buffer *b, const struct btrfs_key *key,
2547 int level, int *prev_cmp, int *slot)
2549 if (*prev_cmp != 0) {
2550 *prev_cmp = btrfs_bin_search(b, key, level, slot);
2559 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2560 u64 iobjectid, u64 ioff, u8 key_type,
2561 struct btrfs_key *found_key)
2564 struct btrfs_key key;
2565 struct extent_buffer *eb;
2570 key.type = key_type;
2571 key.objectid = iobjectid;
2574 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2578 eb = path->nodes[0];
2579 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2580 ret = btrfs_next_leaf(fs_root, path);
2583 eb = path->nodes[0];
2586 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2587 if (found_key->type != key.type ||
2588 found_key->objectid != key.objectid)
2594 static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
2595 struct btrfs_path *p,
2596 int write_lock_level)
2598 struct btrfs_fs_info *fs_info = root->fs_info;
2599 struct extent_buffer *b;
2603 /* We try very hard to do read locks on the root */
2604 root_lock = BTRFS_READ_LOCK;
2606 if (p->search_commit_root) {
2608 * The commit roots are read only so we always do read locks,
2609 * and we always must hold the commit_root_sem when doing
2610 * searches on them, the only exception is send where we don't
2611 * want to block transaction commits for a long time, so
2612 * we need to clone the commit root in order to avoid races
2613 * with transaction commits that create a snapshot of one of
2614 * the roots used by a send operation.
2616 if (p->need_commit_sem) {
2617 down_read(&fs_info->commit_root_sem);
2618 b = btrfs_clone_extent_buffer(root->commit_root);
2619 up_read(&fs_info->commit_root_sem);
2621 return ERR_PTR(-ENOMEM);
2624 b = root->commit_root;
2625 atomic_inc(&b->refs);
2627 level = btrfs_header_level(b);
2629 * Ensure that all callers have set skip_locking when
2630 * p->search_commit_root = 1.
2632 ASSERT(p->skip_locking == 1);
2637 if (p->skip_locking) {
2638 b = btrfs_root_node(root);
2639 level = btrfs_header_level(b);
2644 * If the level is set to maximum, we can skip trying to get the read
2647 if (write_lock_level < BTRFS_MAX_LEVEL) {
2649 * We don't know the level of the root node until we actually
2650 * have it read locked
2652 b = btrfs_read_lock_root_node(root);
2653 level = btrfs_header_level(b);
2654 if (level > write_lock_level)
2657 /* Whoops, must trade for write lock */
2658 btrfs_tree_read_unlock(b);
2659 free_extent_buffer(b);
2662 b = btrfs_lock_root_node(root);
2663 root_lock = BTRFS_WRITE_LOCK;
2665 /* The level might have changed, check again */
2666 level = btrfs_header_level(b);
2669 p->nodes[level] = b;
2670 if (!p->skip_locking)
2671 p->locks[level] = root_lock;
2673 * Callers are responsible for dropping b's references.
2680 * btrfs_search_slot - look for a key in a tree and perform necessary
2681 * modifications to preserve tree invariants.
2683 * @trans: Handle of transaction, used when modifying the tree
2684 * @p: Holds all btree nodes along the search path
2685 * @root: The root node of the tree
2686 * @key: The key we are looking for
2687 * @ins_len: Indicates purpose of search, for inserts it is 1, for
2688 * deletions it's -1. 0 for plain searches
2689 * @cow: boolean should CoW operations be performed. Must always be 1
2690 * when modifying the tree.
2692 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2693 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2695 * If @key is found, 0 is returned and you can find the item in the leaf level
2696 * of the path (level 0)
2698 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2699 * points to the slot where it should be inserted
2701 * If an error is encountered while searching the tree a negative error number
2704 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2705 const struct btrfs_key *key, struct btrfs_path *p,
2706 int ins_len, int cow)
2708 struct extent_buffer *b;
2713 int lowest_unlock = 1;
2714 /* everything at write_lock_level or lower must be write locked */
2715 int write_lock_level = 0;
2716 u8 lowest_level = 0;
2717 int min_write_lock_level;
2720 lowest_level = p->lowest_level;
2721 WARN_ON(lowest_level && ins_len > 0);
2722 WARN_ON(p->nodes[0] != NULL);
2723 BUG_ON(!cow && ins_len);
2728 /* when we are removing items, we might have to go up to level
2729 * two as we update tree pointers Make sure we keep write
2730 * for those levels as well
2732 write_lock_level = 2;
2733 } else if (ins_len > 0) {
2735 * for inserting items, make sure we have a write lock on
2736 * level 1 so we can update keys
2738 write_lock_level = 1;
2742 write_lock_level = -1;
2744 if (cow && (p->keep_locks || p->lowest_level))
2745 write_lock_level = BTRFS_MAX_LEVEL;
2747 min_write_lock_level = write_lock_level;
2751 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2760 level = btrfs_header_level(b);
2763 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2766 * if we don't really need to cow this block
2767 * then we don't want to set the path blocking,
2768 * so we test it here
2770 if (!should_cow_block(trans, root, b)) {
2771 trans->dirty = true;
2776 * must have write locks on this node and the
2779 if (level > write_lock_level ||
2780 (level + 1 > write_lock_level &&
2781 level + 1 < BTRFS_MAX_LEVEL &&
2782 p->nodes[level + 1])) {
2783 write_lock_level = level + 1;
2784 btrfs_release_path(p);
2788 btrfs_set_path_blocking(p);
2790 err = btrfs_cow_block(trans, root, b, NULL, 0,
2793 err = btrfs_cow_block(trans, root, b,
2794 p->nodes[level + 1],
2795 p->slots[level + 1], &b);
2802 p->nodes[level] = b;
2804 * Leave path with blocking locks to avoid massive
2805 * lock context switch, this is made on purpose.
2809 * we have a lock on b and as long as we aren't changing
2810 * the tree, there is no way to for the items in b to change.
2811 * It is safe to drop the lock on our parent before we
2812 * go through the expensive btree search on b.
2814 * If we're inserting or deleting (ins_len != 0), then we might
2815 * be changing slot zero, which may require changing the parent.
2816 * So, we can't drop the lock until after we know which slot
2817 * we're operating on.
2819 if (!ins_len && !p->keep_locks) {
2822 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2823 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2828 ret = key_search(b, key, level, &prev_cmp, &slot);
2833 p->slots[level] = slot;
2835 btrfs_leaf_free_space(b) < ins_len) {
2836 if (write_lock_level < 1) {
2837 write_lock_level = 1;
2838 btrfs_release_path(p);
2842 btrfs_set_path_blocking(p);
2843 err = split_leaf(trans, root, key,
2844 p, ins_len, ret == 0);
2852 if (!p->search_for_split)
2853 unlock_up(p, level, lowest_unlock,
2854 min_write_lock_level, NULL);
2857 if (ret && slot > 0) {
2861 p->slots[level] = slot;
2862 err = setup_nodes_for_search(trans, root, p, b, level, ins_len,
2870 b = p->nodes[level];
2871 slot = p->slots[level];
2874 * Slot 0 is special, if we change the key we have to update
2875 * the parent pointer which means we must have a write lock on
2878 if (slot == 0 && ins_len && write_lock_level < level + 1) {
2879 write_lock_level = level + 1;
2880 btrfs_release_path(p);
2884 unlock_up(p, level, lowest_unlock, min_write_lock_level,
2887 if (level == lowest_level) {
2893 err = read_block_for_search(root, p, &b, level, slot, key);
2901 if (!p->skip_locking) {
2902 level = btrfs_header_level(b);
2903 if (level <= write_lock_level) {
2904 if (!btrfs_try_tree_write_lock(b)) {
2905 btrfs_set_path_blocking(p);
2908 p->locks[level] = BTRFS_WRITE_LOCK;
2910 if (!btrfs_tree_read_lock_atomic(b)) {
2911 btrfs_set_path_blocking(p);
2912 btrfs_tree_read_lock(b);
2914 p->locks[level] = BTRFS_READ_LOCK;
2916 p->nodes[level] = b;
2922 * we don't really know what they plan on doing with the path
2923 * from here on, so for now just mark it as blocking
2925 if (!p->leave_spinning)
2926 btrfs_set_path_blocking(p);
2927 if (ret < 0 && !p->skip_release_on_error)
2928 btrfs_release_path(p);
2933 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2934 * current state of the tree together with the operations recorded in the tree
2935 * modification log to search for the key in a previous version of this tree, as
2936 * denoted by the time_seq parameter.
2938 * Naturally, there is no support for insert, delete or cow operations.
2940 * The resulting path and return value will be set up as if we called
2941 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2943 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2944 struct btrfs_path *p, u64 time_seq)
2946 struct btrfs_fs_info *fs_info = root->fs_info;
2947 struct extent_buffer *b;
2952 int lowest_unlock = 1;
2953 u8 lowest_level = 0;
2956 lowest_level = p->lowest_level;
2957 WARN_ON(p->nodes[0] != NULL);
2959 if (p->search_commit_root) {
2961 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2965 b = get_old_root(root, time_seq);
2970 level = btrfs_header_level(b);
2971 p->locks[level] = BTRFS_READ_LOCK;
2976 level = btrfs_header_level(b);
2977 p->nodes[level] = b;
2980 * we have a lock on b and as long as we aren't changing
2981 * the tree, there is no way to for the items in b to change.
2982 * It is safe to drop the lock on our parent before we
2983 * go through the expensive btree search on b.
2985 btrfs_unlock_up_safe(p, level + 1);
2988 * Since we can unwind ebs we want to do a real search every
2992 ret = key_search(b, key, level, &prev_cmp, &slot);
2997 p->slots[level] = slot;
2998 unlock_up(p, level, lowest_unlock, 0, NULL);
3002 if (ret && slot > 0) {
3006 p->slots[level] = slot;
3007 unlock_up(p, level, lowest_unlock, 0, NULL);
3009 if (level == lowest_level) {
3015 err = read_block_for_search(root, p, &b, level, slot, key);
3023 level = btrfs_header_level(b);
3024 if (!btrfs_tree_read_lock_atomic(b)) {
3025 btrfs_set_path_blocking(p);
3026 btrfs_tree_read_lock(b);
3028 b = tree_mod_log_rewind(fs_info, p, b, time_seq);
3033 p->locks[level] = BTRFS_READ_LOCK;
3034 p->nodes[level] = b;
3038 if (!p->leave_spinning)
3039 btrfs_set_path_blocking(p);
3041 btrfs_release_path(p);
3047 * helper to use instead of search slot if no exact match is needed but
3048 * instead the next or previous item should be returned.
3049 * When find_higher is true, the next higher item is returned, the next lower
3051 * When return_any and find_higher are both true, and no higher item is found,
3052 * return the next lower instead.
3053 * When return_any is true and find_higher is false, and no lower item is found,
3054 * return the next higher instead.
3055 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3058 int btrfs_search_slot_for_read(struct btrfs_root *root,
3059 const struct btrfs_key *key,
3060 struct btrfs_path *p, int find_higher,
3064 struct extent_buffer *leaf;
3067 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3071 * a return value of 1 means the path is at the position where the
3072 * item should be inserted. Normally this is the next bigger item,
3073 * but in case the previous item is the last in a leaf, path points
3074 * to the first free slot in the previous leaf, i.e. at an invalid
3080 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3081 ret = btrfs_next_leaf(root, p);
3087 * no higher item found, return the next
3092 btrfs_release_path(p);
3096 if (p->slots[0] == 0) {
3097 ret = btrfs_prev_leaf(root, p);
3102 if (p->slots[0] == btrfs_header_nritems(leaf))
3109 * no lower item found, return the next
3114 btrfs_release_path(p);
3124 * adjust the pointers going up the tree, starting at level
3125 * making sure the right key of each node is points to 'key'.
3126 * This is used after shifting pointers to the left, so it stops
3127 * fixing up pointers when a given leaf/node is not in slot 0 of the
3131 static void fixup_low_keys(struct btrfs_path *path,
3132 struct btrfs_disk_key *key, int level)
3135 struct extent_buffer *t;
3138 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3139 int tslot = path->slots[i];
3141 if (!path->nodes[i])
3144 ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE,
3147 btrfs_set_node_key(t, key, tslot);
3148 btrfs_mark_buffer_dirty(path->nodes[i]);
3157 * This function isn't completely safe. It's the caller's responsibility
3158 * that the new key won't break the order
3160 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3161 struct btrfs_path *path,
3162 const struct btrfs_key *new_key)
3164 struct btrfs_disk_key disk_key;
3165 struct extent_buffer *eb;
3168 eb = path->nodes[0];
3169 slot = path->slots[0];
3171 btrfs_item_key(eb, &disk_key, slot - 1);
3172 if (unlikely(comp_keys(&disk_key, new_key) >= 0)) {
3174 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3175 slot, btrfs_disk_key_objectid(&disk_key),
3176 btrfs_disk_key_type(&disk_key),
3177 btrfs_disk_key_offset(&disk_key),
3178 new_key->objectid, new_key->type,
3180 btrfs_print_leaf(eb);
3184 if (slot < btrfs_header_nritems(eb) - 1) {
3185 btrfs_item_key(eb, &disk_key, slot + 1);
3186 if (unlikely(comp_keys(&disk_key, new_key) <= 0)) {
3188 "slot %u key (%llu %u %llu) new key (%llu %u %llu)",
3189 slot, btrfs_disk_key_objectid(&disk_key),
3190 btrfs_disk_key_type(&disk_key),
3191 btrfs_disk_key_offset(&disk_key),
3192 new_key->objectid, new_key->type,
3194 btrfs_print_leaf(eb);
3199 btrfs_cpu_key_to_disk(&disk_key, new_key);
3200 btrfs_set_item_key(eb, &disk_key, slot);
3201 btrfs_mark_buffer_dirty(eb);
3203 fixup_low_keys(path, &disk_key, 1);
3207 * try to push data from one node into the next node left in the
3210 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3211 * error, and > 0 if there was no room in the left hand block.
3213 static int push_node_left(struct btrfs_trans_handle *trans,
3214 struct extent_buffer *dst,
3215 struct extent_buffer *src, int empty)
3217 struct btrfs_fs_info *fs_info = trans->fs_info;
3223 src_nritems = btrfs_header_nritems(src);
3224 dst_nritems = btrfs_header_nritems(dst);
3225 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3226 WARN_ON(btrfs_header_generation(src) != trans->transid);
3227 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3229 if (!empty && src_nritems <= 8)
3232 if (push_items <= 0)
3236 push_items = min(src_nritems, push_items);
3237 if (push_items < src_nritems) {
3238 /* leave at least 8 pointers in the node if
3239 * we aren't going to empty it
3241 if (src_nritems - push_items < 8) {
3242 if (push_items <= 8)
3248 push_items = min(src_nritems - 8, push_items);
3250 ret = tree_mod_log_eb_copy(dst, src, dst_nritems, 0, push_items);
3252 btrfs_abort_transaction(trans, ret);
3255 copy_extent_buffer(dst, src,
3256 btrfs_node_key_ptr_offset(dst_nritems),
3257 btrfs_node_key_ptr_offset(0),
3258 push_items * sizeof(struct btrfs_key_ptr));
3260 if (push_items < src_nritems) {
3262 * Don't call tree_mod_log_insert_move here, key removal was
3263 * already fully logged by tree_mod_log_eb_copy above.
3265 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3266 btrfs_node_key_ptr_offset(push_items),
3267 (src_nritems - push_items) *
3268 sizeof(struct btrfs_key_ptr));
3270 btrfs_set_header_nritems(src, src_nritems - push_items);
3271 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3272 btrfs_mark_buffer_dirty(src);
3273 btrfs_mark_buffer_dirty(dst);
3279 * try to push data from one node into the next node right in the
3282 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3283 * error, and > 0 if there was no room in the right hand block.
3285 * this will only push up to 1/2 the contents of the left node over
3287 static int balance_node_right(struct btrfs_trans_handle *trans,
3288 struct extent_buffer *dst,
3289 struct extent_buffer *src)
3291 struct btrfs_fs_info *fs_info = trans->fs_info;
3298 WARN_ON(btrfs_header_generation(src) != trans->transid);
3299 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3301 src_nritems = btrfs_header_nritems(src);
3302 dst_nritems = btrfs_header_nritems(dst);
3303 push_items = BTRFS_NODEPTRS_PER_BLOCK(fs_info) - dst_nritems;
3304 if (push_items <= 0)
3307 if (src_nritems < 4)
3310 max_push = src_nritems / 2 + 1;
3311 /* don't try to empty the node */
3312 if (max_push >= src_nritems)
3315 if (max_push < push_items)
3316 push_items = max_push;
3318 ret = tree_mod_log_insert_move(dst, push_items, 0, dst_nritems);
3320 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3321 btrfs_node_key_ptr_offset(0),
3323 sizeof(struct btrfs_key_ptr));
3325 ret = tree_mod_log_eb_copy(dst, src, 0, src_nritems - push_items,
3328 btrfs_abort_transaction(trans, ret);
3331 copy_extent_buffer(dst, src,
3332 btrfs_node_key_ptr_offset(0),
3333 btrfs_node_key_ptr_offset(src_nritems - push_items),
3334 push_items * sizeof(struct btrfs_key_ptr));
3336 btrfs_set_header_nritems(src, src_nritems - push_items);
3337 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3339 btrfs_mark_buffer_dirty(src);
3340 btrfs_mark_buffer_dirty(dst);
3346 * helper function to insert a new root level in the tree.
3347 * A new node is allocated, and a single item is inserted to
3348 * point to the existing root
3350 * returns zero on success or < 0 on failure.
3352 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3353 struct btrfs_root *root,
3354 struct btrfs_path *path, int level)
3356 struct btrfs_fs_info *fs_info = root->fs_info;
3358 struct extent_buffer *lower;
3359 struct extent_buffer *c;
3360 struct extent_buffer *old;
3361 struct btrfs_disk_key lower_key;
3364 BUG_ON(path->nodes[level]);
3365 BUG_ON(path->nodes[level-1] != root->node);
3367 lower = path->nodes[level-1];
3369 btrfs_item_key(lower, &lower_key, 0);
3371 btrfs_node_key(lower, &lower_key, 0);
3373 c = alloc_tree_block_no_bg_flush(trans, root, 0, &lower_key, level,
3374 root->node->start, 0);
3378 root_add_used(root, fs_info->nodesize);
3380 btrfs_set_header_nritems(c, 1);
3381 btrfs_set_node_key(c, &lower_key, 0);
3382 btrfs_set_node_blockptr(c, 0, lower->start);
3383 lower_gen = btrfs_header_generation(lower);
3384 WARN_ON(lower_gen != trans->transid);
3386 btrfs_set_node_ptr_generation(c, 0, lower_gen);
3388 btrfs_mark_buffer_dirty(c);
3391 ret = tree_mod_log_insert_root(root->node, c, 0);
3393 rcu_assign_pointer(root->node, c);
3395 /* the super has an extra ref to root->node */
3396 free_extent_buffer(old);
3398 add_root_to_dirty_list(root);
3399 atomic_inc(&c->refs);
3400 path->nodes[level] = c;
3401 path->locks[level] = BTRFS_WRITE_LOCK_BLOCKING;
3402 path->slots[level] = 0;
3407 * worker function to insert a single pointer in a node.
3408 * the node should have enough room for the pointer already
3410 * slot and level indicate where you want the key to go, and
3411 * blocknr is the block the key points to.
3413 static void insert_ptr(struct btrfs_trans_handle *trans,
3414 struct btrfs_path *path,
3415 struct btrfs_disk_key *key, u64 bytenr,
3416 int slot, int level)
3418 struct extent_buffer *lower;
3422 BUG_ON(!path->nodes[level]);
3423 btrfs_assert_tree_locked(path->nodes[level]);
3424 lower = path->nodes[level];
3425 nritems = btrfs_header_nritems(lower);
3426 BUG_ON(slot > nritems);
3427 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(trans->fs_info));
3428 if (slot != nritems) {
3430 ret = tree_mod_log_insert_move(lower, slot + 1, slot,
3434 memmove_extent_buffer(lower,
3435 btrfs_node_key_ptr_offset(slot + 1),
3436 btrfs_node_key_ptr_offset(slot),
3437 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3440 ret = tree_mod_log_insert_key(lower, slot, MOD_LOG_KEY_ADD,
3444 btrfs_set_node_key(lower, key, slot);
3445 btrfs_set_node_blockptr(lower, slot, bytenr);
3446 WARN_ON(trans->transid == 0);
3447 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3448 btrfs_set_header_nritems(lower, nritems + 1);
3449 btrfs_mark_buffer_dirty(lower);
3453 * split the node at the specified level in path in two.
3454 * The path is corrected to point to the appropriate node after the split
3456 * Before splitting this tries to make some room in the node by pushing
3457 * left and right, if either one works, it returns right away.
3459 * returns 0 on success and < 0 on failure
3461 static noinline int split_node(struct btrfs_trans_handle *trans,
3462 struct btrfs_root *root,
3463 struct btrfs_path *path, int level)
3465 struct btrfs_fs_info *fs_info = root->fs_info;
3466 struct extent_buffer *c;
3467 struct extent_buffer *split;
3468 struct btrfs_disk_key disk_key;
3473 c = path->nodes[level];
3474 WARN_ON(btrfs_header_generation(c) != trans->transid);
3475 if (c == root->node) {
3477 * trying to split the root, lets make a new one
3479 * tree mod log: We don't log_removal old root in
3480 * insert_new_root, because that root buffer will be kept as a
3481 * normal node. We are going to log removal of half of the
3482 * elements below with tree_mod_log_eb_copy. We're holding a
3483 * tree lock on the buffer, which is why we cannot race with
3484 * other tree_mod_log users.
3486 ret = insert_new_root(trans, root, path, level + 1);
3490 ret = push_nodes_for_insert(trans, root, path, level);
3491 c = path->nodes[level];
3492 if (!ret && btrfs_header_nritems(c) <
3493 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3)
3499 c_nritems = btrfs_header_nritems(c);
3500 mid = (c_nritems + 1) / 2;
3501 btrfs_node_key(c, &disk_key, mid);
3503 split = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, level,
3506 return PTR_ERR(split);
3508 root_add_used(root, fs_info->nodesize);
3509 ASSERT(btrfs_header_level(c) == level);
3511 ret = tree_mod_log_eb_copy(split, c, 0, mid, c_nritems - mid);
3513 btrfs_abort_transaction(trans, ret);
3516 copy_extent_buffer(split, c,
3517 btrfs_node_key_ptr_offset(0),
3518 btrfs_node_key_ptr_offset(mid),
3519 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3520 btrfs_set_header_nritems(split, c_nritems - mid);
3521 btrfs_set_header_nritems(c, mid);
3524 btrfs_mark_buffer_dirty(c);
3525 btrfs_mark_buffer_dirty(split);
3527 insert_ptr(trans, path, &disk_key, split->start,
3528 path->slots[level + 1] + 1, level + 1);
3530 if (path->slots[level] >= mid) {
3531 path->slots[level] -= mid;
3532 btrfs_tree_unlock(c);
3533 free_extent_buffer(c);
3534 path->nodes[level] = split;
3535 path->slots[level + 1] += 1;
3537 btrfs_tree_unlock(split);
3538 free_extent_buffer(split);
3544 * how many bytes are required to store the items in a leaf. start
3545 * and nr indicate which items in the leaf to check. This totals up the
3546 * space used both by the item structs and the item data
3548 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3550 struct btrfs_item *start_item;
3551 struct btrfs_item *end_item;
3552 struct btrfs_map_token token;
3554 int nritems = btrfs_header_nritems(l);
3555 int end = min(nritems, start + nr) - 1;
3559 btrfs_init_map_token(&token, l);
3560 start_item = btrfs_item_nr(start);
3561 end_item = btrfs_item_nr(end);
3562 data_len = btrfs_token_item_offset(l, start_item, &token) +
3563 btrfs_token_item_size(l, start_item, &token);
3564 data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3565 data_len += sizeof(struct btrfs_item) * nr;
3566 WARN_ON(data_len < 0);
3571 * The space between the end of the leaf items and
3572 * the start of the leaf data. IOW, how much room
3573 * the leaf has left for both items and data
3575 noinline int btrfs_leaf_free_space(struct extent_buffer *leaf)
3577 struct btrfs_fs_info *fs_info = leaf->fs_info;
3578 int nritems = btrfs_header_nritems(leaf);
3581 ret = BTRFS_LEAF_DATA_SIZE(fs_info) - leaf_space_used(leaf, 0, nritems);
3584 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3586 (unsigned long) BTRFS_LEAF_DATA_SIZE(fs_info),
3587 leaf_space_used(leaf, 0, nritems), nritems);
3593 * min slot controls the lowest index we're willing to push to the
3594 * right. We'll push up to and including min_slot, but no lower
3596 static noinline int __push_leaf_right(struct btrfs_path *path,
3597 int data_size, int empty,
3598 struct extent_buffer *right,
3599 int free_space, u32 left_nritems,
3602 struct btrfs_fs_info *fs_info = right->fs_info;
3603 struct extent_buffer *left = path->nodes[0];
3604 struct extent_buffer *upper = path->nodes[1];
3605 struct btrfs_map_token token;
3606 struct btrfs_disk_key disk_key;
3611 struct btrfs_item *item;
3620 nr = max_t(u32, 1, min_slot);
3622 if (path->slots[0] >= left_nritems)
3623 push_space += data_size;
3625 slot = path->slots[1];
3626 i = left_nritems - 1;
3628 item = btrfs_item_nr(i);
3630 if (!empty && push_items > 0) {
3631 if (path->slots[0] > i)
3633 if (path->slots[0] == i) {
3634 int space = btrfs_leaf_free_space(left);
3636 if (space + push_space * 2 > free_space)
3641 if (path->slots[0] == i)
3642 push_space += data_size;
3644 this_item_size = btrfs_item_size(left, item);
3645 if (this_item_size + sizeof(*item) + push_space > free_space)
3649 push_space += this_item_size + sizeof(*item);
3655 if (push_items == 0)
3658 WARN_ON(!empty && push_items == left_nritems);
3660 /* push left to right */
3661 right_nritems = btrfs_header_nritems(right);
3663 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3664 push_space -= leaf_data_end(left);
3666 /* make room in the right data area */
3667 data_end = leaf_data_end(right);
3668 memmove_extent_buffer(right,
3669 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3670 BTRFS_LEAF_DATA_OFFSET + data_end,
3671 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3673 /* copy from the left data area */
3674 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3675 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3676 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3679 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3680 btrfs_item_nr_offset(0),
3681 right_nritems * sizeof(struct btrfs_item));
3683 /* copy the items from left to right */
3684 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3685 btrfs_item_nr_offset(left_nritems - push_items),
3686 push_items * sizeof(struct btrfs_item));
3688 /* update the item pointers */
3689 btrfs_init_map_token(&token, right);
3690 right_nritems += push_items;
3691 btrfs_set_header_nritems(right, right_nritems);
3692 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3693 for (i = 0; i < right_nritems; i++) {
3694 item = btrfs_item_nr(i);
3695 push_space -= btrfs_token_item_size(right, item, &token);
3696 btrfs_set_token_item_offset(right, item, push_space, &token);
3699 left_nritems -= push_items;
3700 btrfs_set_header_nritems(left, left_nritems);
3703 btrfs_mark_buffer_dirty(left);
3705 btrfs_clean_tree_block(left);
3707 btrfs_mark_buffer_dirty(right);
3709 btrfs_item_key(right, &disk_key, 0);
3710 btrfs_set_node_key(upper, &disk_key, slot + 1);
3711 btrfs_mark_buffer_dirty(upper);
3713 /* then fixup the leaf pointer in the path */
3714 if (path->slots[0] >= left_nritems) {
3715 path->slots[0] -= left_nritems;
3716 if (btrfs_header_nritems(path->nodes[0]) == 0)
3717 btrfs_clean_tree_block(path->nodes[0]);
3718 btrfs_tree_unlock(path->nodes[0]);
3719 free_extent_buffer(path->nodes[0]);
3720 path->nodes[0] = right;
3721 path->slots[1] += 1;
3723 btrfs_tree_unlock(right);
3724 free_extent_buffer(right);
3729 btrfs_tree_unlock(right);
3730 free_extent_buffer(right);
3735 * push some data in the path leaf to the right, trying to free up at
3736 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3738 * returns 1 if the push failed because the other node didn't have enough
3739 * room, 0 if everything worked out and < 0 if there were major errors.
3741 * this will push starting from min_slot to the end of the leaf. It won't
3742 * push any slot lower than min_slot
3744 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3745 *root, struct btrfs_path *path,
3746 int min_data_size, int data_size,
3747 int empty, u32 min_slot)
3749 struct extent_buffer *left = path->nodes[0];
3750 struct extent_buffer *right;
3751 struct extent_buffer *upper;
3757 if (!path->nodes[1])
3760 slot = path->slots[1];
3761 upper = path->nodes[1];
3762 if (slot >= btrfs_header_nritems(upper) - 1)
3765 btrfs_assert_tree_locked(path->nodes[1]);
3767 right = btrfs_read_node_slot(upper, slot + 1);
3769 * slot + 1 is not valid or we fail to read the right node,
3770 * no big deal, just return.
3775 btrfs_tree_lock(right);
3776 btrfs_set_lock_blocking_write(right);
3778 free_space = btrfs_leaf_free_space(right);
3779 if (free_space < data_size)
3782 /* cow and double check */
3783 ret = btrfs_cow_block(trans, root, right, upper,
3788 free_space = btrfs_leaf_free_space(right);
3789 if (free_space < data_size)
3792 left_nritems = btrfs_header_nritems(left);
3793 if (left_nritems == 0)
3796 if (path->slots[0] == left_nritems && !empty) {
3797 /* Key greater than all keys in the leaf, right neighbor has
3798 * enough room for it and we're not emptying our leaf to delete
3799 * it, therefore use right neighbor to insert the new item and
3800 * no need to touch/dirty our left leaf. */
3801 btrfs_tree_unlock(left);
3802 free_extent_buffer(left);
3803 path->nodes[0] = right;
3809 return __push_leaf_right(path, min_data_size, empty,
3810 right, free_space, left_nritems, min_slot);
3812 btrfs_tree_unlock(right);
3813 free_extent_buffer(right);
3818 * push some data in the path leaf to the left, trying to free up at
3819 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3821 * max_slot can put a limit on how far into the leaf we'll push items. The
3822 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3825 static noinline int __push_leaf_left(struct btrfs_path *path, int data_size,
3826 int empty, struct extent_buffer *left,
3827 int free_space, u32 right_nritems,
3830 struct btrfs_fs_info *fs_info = left->fs_info;
3831 struct btrfs_disk_key disk_key;
3832 struct extent_buffer *right = path->nodes[0];
3836 struct btrfs_item *item;
3837 u32 old_left_nritems;
3841 u32 old_left_item_size;
3842 struct btrfs_map_token token;
3845 nr = min(right_nritems, max_slot);
3847 nr = min(right_nritems - 1, max_slot);
3849 for (i = 0; i < nr; i++) {
3850 item = btrfs_item_nr(i);
3852 if (!empty && push_items > 0) {
3853 if (path->slots[0] < i)
3855 if (path->slots[0] == i) {
3856 int space = btrfs_leaf_free_space(right);
3858 if (space + push_space * 2 > free_space)
3863 if (path->slots[0] == i)
3864 push_space += data_size;
3866 this_item_size = btrfs_item_size(right, item);
3867 if (this_item_size + sizeof(*item) + push_space > free_space)
3871 push_space += this_item_size + sizeof(*item);
3874 if (push_items == 0) {
3878 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3880 /* push data from right to left */
3881 copy_extent_buffer(left, right,
3882 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3883 btrfs_item_nr_offset(0),
3884 push_items * sizeof(struct btrfs_item));
3886 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3887 btrfs_item_offset_nr(right, push_items - 1);
3889 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3890 leaf_data_end(left) - push_space,
3891 BTRFS_LEAF_DATA_OFFSET +
3892 btrfs_item_offset_nr(right, push_items - 1),
3894 old_left_nritems = btrfs_header_nritems(left);
3895 BUG_ON(old_left_nritems <= 0);
3897 btrfs_init_map_token(&token, left);
3898 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3899 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3902 item = btrfs_item_nr(i);
3904 ioff = btrfs_token_item_offset(left, item, &token);
3905 btrfs_set_token_item_offset(left, item,
3906 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size),
3909 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3911 /* fixup right node */
3912 if (push_items > right_nritems)
3913 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3916 if (push_items < right_nritems) {
3917 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3918 leaf_data_end(right);
3919 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3920 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3921 BTRFS_LEAF_DATA_OFFSET +
3922 leaf_data_end(right), push_space);
3924 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3925 btrfs_item_nr_offset(push_items),
3926 (btrfs_header_nritems(right) - push_items) *
3927 sizeof(struct btrfs_item));
3930 btrfs_init_map_token(&token, right);
3931 right_nritems -= push_items;
3932 btrfs_set_header_nritems(right, right_nritems);
3933 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3934 for (i = 0; i < right_nritems; i++) {
3935 item = btrfs_item_nr(i);
3937 push_space = push_space - btrfs_token_item_size(right,
3939 btrfs_set_token_item_offset(right, item, push_space, &token);
3942 btrfs_mark_buffer_dirty(left);
3944 btrfs_mark_buffer_dirty(right);
3946 btrfs_clean_tree_block(right);
3948 btrfs_item_key(right, &disk_key, 0);
3949 fixup_low_keys(path, &disk_key, 1);
3951 /* then fixup the leaf pointer in the path */
3952 if (path->slots[0] < push_items) {
3953 path->slots[0] += old_left_nritems;
3954 btrfs_tree_unlock(path->nodes[0]);
3955 free_extent_buffer(path->nodes[0]);
3956 path->nodes[0] = left;
3957 path->slots[1] -= 1;
3959 btrfs_tree_unlock(left);
3960 free_extent_buffer(left);
3961 path->slots[0] -= push_items;
3963 BUG_ON(path->slots[0] < 0);
3966 btrfs_tree_unlock(left);
3967 free_extent_buffer(left);
3972 * push some data in the path leaf to the left, trying to free up at
3973 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3975 * max_slot can put a limit on how far into the leaf we'll push items. The
3976 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3979 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3980 *root, struct btrfs_path *path, int min_data_size,
3981 int data_size, int empty, u32 max_slot)
3983 struct extent_buffer *right = path->nodes[0];
3984 struct extent_buffer *left;
3990 slot = path->slots[1];
3993 if (!path->nodes[1])
3996 right_nritems = btrfs_header_nritems(right);
3997 if (right_nritems == 0)
4000 btrfs_assert_tree_locked(path->nodes[1]);
4002 left = btrfs_read_node_slot(path->nodes[1], slot - 1);
4004 * slot - 1 is not valid or we fail to read the left node,
4005 * no big deal, just return.
4010 btrfs_tree_lock(left);
4011 btrfs_set_lock_blocking_write(left);
4013 free_space = btrfs_leaf_free_space(left);
4014 if (free_space < data_size) {
4019 /* cow and double check */
4020 ret = btrfs_cow_block(trans, root, left,
4021 path->nodes[1], slot - 1, &left);
4023 /* we hit -ENOSPC, but it isn't fatal here */
4029 free_space = btrfs_leaf_free_space(left);
4030 if (free_space < data_size) {
4035 return __push_leaf_left(path, min_data_size,
4036 empty, left, free_space, right_nritems,
4039 btrfs_tree_unlock(left);
4040 free_extent_buffer(left);
4045 * split the path's leaf in two, making sure there is at least data_size
4046 * available for the resulting leaf level of the path.
4048 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4049 struct btrfs_path *path,
4050 struct extent_buffer *l,
4051 struct extent_buffer *right,
4052 int slot, int mid, int nritems)
4054 struct btrfs_fs_info *fs_info = trans->fs_info;
4058 struct btrfs_disk_key disk_key;
4059 struct btrfs_map_token token;
4061 nritems = nritems - mid;
4062 btrfs_set_header_nritems(right, nritems);
4063 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
4065 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4066 btrfs_item_nr_offset(mid),
4067 nritems * sizeof(struct btrfs_item));
4069 copy_extent_buffer(right, l,
4070 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4071 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4072 leaf_data_end(l), data_copy_size);
4074 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
4076 btrfs_init_map_token(&token, right);
4077 for (i = 0; i < nritems; i++) {
4078 struct btrfs_item *item = btrfs_item_nr(i);
4081 ioff = btrfs_token_item_offset(right, item, &token);
4082 btrfs_set_token_item_offset(right, item,
4083 ioff + rt_data_off, &token);
4086 btrfs_set_header_nritems(l, mid);
4087 btrfs_item_key(right, &disk_key, 0);
4088 insert_ptr(trans, path, &disk_key, right->start, path->slots[1] + 1, 1);
4090 btrfs_mark_buffer_dirty(right);
4091 btrfs_mark_buffer_dirty(l);
4092 BUG_ON(path->slots[0] != slot);
4095 btrfs_tree_unlock(path->nodes[0]);
4096 free_extent_buffer(path->nodes[0]);
4097 path->nodes[0] = right;
4098 path->slots[0] -= mid;
4099 path->slots[1] += 1;
4101 btrfs_tree_unlock(right);
4102 free_extent_buffer(right);
4105 BUG_ON(path->slots[0] < 0);
4109 * double splits happen when we need to insert a big item in the middle
4110 * of a leaf. A double split can leave us with 3 mostly empty leaves:
4111 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4114 * We avoid this by trying to push the items on either side of our target
4115 * into the adjacent leaves. If all goes well we can avoid the double split
4118 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4119 struct btrfs_root *root,
4120 struct btrfs_path *path,
4127 int space_needed = data_size;
4129 slot = path->slots[0];
4130 if (slot < btrfs_header_nritems(path->nodes[0]))
4131 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4134 * try to push all the items after our slot into the
4137 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4144 nritems = btrfs_header_nritems(path->nodes[0]);
4146 * our goal is to get our slot at the start or end of a leaf. If
4147 * we've done so we're done
4149 if (path->slots[0] == 0 || path->slots[0] == nritems)
4152 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4155 /* try to push all the items before our slot into the next leaf */
4156 slot = path->slots[0];
4157 space_needed = data_size;
4159 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4160 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4173 * split the path's leaf in two, making sure there is at least data_size
4174 * available for the resulting leaf level of the path.
4176 * returns 0 if all went well and < 0 on failure.
4178 static noinline int split_leaf(struct btrfs_trans_handle *trans,
4179 struct btrfs_root *root,
4180 const struct btrfs_key *ins_key,
4181 struct btrfs_path *path, int data_size,
4184 struct btrfs_disk_key disk_key;
4185 struct extent_buffer *l;
4189 struct extent_buffer *right;
4190 struct btrfs_fs_info *fs_info = root->fs_info;
4194 int num_doubles = 0;
4195 int tried_avoid_double = 0;
4198 slot = path->slots[0];
4199 if (extend && data_size + btrfs_item_size_nr(l, slot) +
4200 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4203 /* first try to make some room by pushing left and right */
4204 if (data_size && path->nodes[1]) {
4205 int space_needed = data_size;
4207 if (slot < btrfs_header_nritems(l))
4208 space_needed -= btrfs_leaf_free_space(l);
4210 wret = push_leaf_right(trans, root, path, space_needed,
4211 space_needed, 0, 0);
4215 space_needed = data_size;
4217 space_needed -= btrfs_leaf_free_space(l);
4218 wret = push_leaf_left(trans, root, path, space_needed,
4219 space_needed, 0, (u32)-1);
4225 /* did the pushes work? */
4226 if (btrfs_leaf_free_space(l) >= data_size)
4230 if (!path->nodes[1]) {
4231 ret = insert_new_root(trans, root, path, 1);
4238 slot = path->slots[0];
4239 nritems = btrfs_header_nritems(l);
4240 mid = (nritems + 1) / 2;
4244 leaf_space_used(l, mid, nritems - mid) + data_size >
4245 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4246 if (slot >= nritems) {
4250 if (mid != nritems &&
4251 leaf_space_used(l, mid, nritems - mid) +
4252 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4253 if (data_size && !tried_avoid_double)
4254 goto push_for_double;
4260 if (leaf_space_used(l, 0, mid) + data_size >
4261 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4262 if (!extend && data_size && slot == 0) {
4264 } else if ((extend || !data_size) && slot == 0) {
4268 if (mid != nritems &&
4269 leaf_space_used(l, mid, nritems - mid) +
4270 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4271 if (data_size && !tried_avoid_double)
4272 goto push_for_double;
4280 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4282 btrfs_item_key(l, &disk_key, mid);
4284 right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
4287 return PTR_ERR(right);
4289 root_add_used(root, fs_info->nodesize);
4293 btrfs_set_header_nritems(right, 0);
4294 insert_ptr(trans, path, &disk_key,
4295 right->start, path->slots[1] + 1, 1);
4296 btrfs_tree_unlock(path->nodes[0]);
4297 free_extent_buffer(path->nodes[0]);
4298 path->nodes[0] = right;
4300 path->slots[1] += 1;
4302 btrfs_set_header_nritems(right, 0);
4303 insert_ptr(trans, path, &disk_key,
4304 right->start, path->slots[1], 1);
4305 btrfs_tree_unlock(path->nodes[0]);
4306 free_extent_buffer(path->nodes[0]);
4307 path->nodes[0] = right;
4309 if (path->slots[1] == 0)
4310 fixup_low_keys(path, &disk_key, 1);
4313 * We create a new leaf 'right' for the required ins_len and
4314 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4315 * the content of ins_len to 'right'.
4320 copy_for_split(trans, path, l, right, slot, mid, nritems);
4323 BUG_ON(num_doubles != 0);
4331 push_for_double_split(trans, root, path, data_size);
4332 tried_avoid_double = 1;
4333 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4338 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4339 struct btrfs_root *root,
4340 struct btrfs_path *path, int ins_len)
4342 struct btrfs_key key;
4343 struct extent_buffer *leaf;
4344 struct btrfs_file_extent_item *fi;
4349 leaf = path->nodes[0];
4350 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4352 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4353 key.type != BTRFS_EXTENT_CSUM_KEY);
4355 if (btrfs_leaf_free_space(leaf) >= ins_len)
4358 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4359 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4360 fi = btrfs_item_ptr(leaf, path->slots[0],
4361 struct btrfs_file_extent_item);
4362 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4364 btrfs_release_path(path);
4366 path->keep_locks = 1;
4367 path->search_for_split = 1;
4368 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4369 path->search_for_split = 0;
4376 leaf = path->nodes[0];
4377 /* if our item isn't there, return now */
4378 if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4381 /* the leaf has changed, it now has room. return now */
4382 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
4385 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4386 fi = btrfs_item_ptr(leaf, path->slots[0],
4387 struct btrfs_file_extent_item);
4388 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4392 btrfs_set_path_blocking(path);
4393 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4397 path->keep_locks = 0;
4398 btrfs_unlock_up_safe(path, 1);
4401 path->keep_locks = 0;
4405 static noinline int split_item(struct btrfs_path *path,
4406 const struct btrfs_key *new_key,
4407 unsigned long split_offset)
4409 struct extent_buffer *leaf;
4410 struct btrfs_item *item;
4411 struct btrfs_item *new_item;
4417 struct btrfs_disk_key disk_key;
4419 leaf = path->nodes[0];
4420 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
4422 btrfs_set_path_blocking(path);
4424 item = btrfs_item_nr(path->slots[0]);
4425 orig_offset = btrfs_item_offset(leaf, item);
4426 item_size = btrfs_item_size(leaf, item);
4428 buf = kmalloc(item_size, GFP_NOFS);
4432 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4433 path->slots[0]), item_size);
4435 slot = path->slots[0] + 1;
4436 nritems = btrfs_header_nritems(leaf);
4437 if (slot != nritems) {
4438 /* shift the items */
4439 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4440 btrfs_item_nr_offset(slot),
4441 (nritems - slot) * sizeof(struct btrfs_item));
4444 btrfs_cpu_key_to_disk(&disk_key, new_key);
4445 btrfs_set_item_key(leaf, &disk_key, slot);
4447 new_item = btrfs_item_nr(slot);
4449 btrfs_set_item_offset(leaf, new_item, orig_offset);
4450 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4452 btrfs_set_item_offset(leaf, item,
4453 orig_offset + item_size - split_offset);
4454 btrfs_set_item_size(leaf, item, split_offset);
4456 btrfs_set_header_nritems(leaf, nritems + 1);
4458 /* write the data for the start of the original item */
4459 write_extent_buffer(leaf, buf,
4460 btrfs_item_ptr_offset(leaf, path->slots[0]),
4463 /* write the data for the new item */
4464 write_extent_buffer(leaf, buf + split_offset,
4465 btrfs_item_ptr_offset(leaf, slot),
4466 item_size - split_offset);
4467 btrfs_mark_buffer_dirty(leaf);
4469 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4475 * This function splits a single item into two items,
4476 * giving 'new_key' to the new item and splitting the
4477 * old one at split_offset (from the start of the item).
4479 * The path may be released by this operation. After
4480 * the split, the path is pointing to the old item. The
4481 * new item is going to be in the same node as the old one.
4483 * Note, the item being split must be smaller enough to live alone on
4484 * a tree block with room for one extra struct btrfs_item
4486 * This allows us to split the item in place, keeping a lock on the
4487 * leaf the entire time.
4489 int btrfs_split_item(struct btrfs_trans_handle *trans,
4490 struct btrfs_root *root,
4491 struct btrfs_path *path,
4492 const struct btrfs_key *new_key,
4493 unsigned long split_offset)
4496 ret = setup_leaf_for_split(trans, root, path,
4497 sizeof(struct btrfs_item));
4501 ret = split_item(path, new_key, split_offset);
4506 * This function duplicate a item, giving 'new_key' to the new item.
4507 * It guarantees both items live in the same tree leaf and the new item
4508 * is contiguous with the original item.
4510 * This allows us to split file extent in place, keeping a lock on the
4511 * leaf the entire time.
4513 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4514 struct btrfs_root *root,
4515 struct btrfs_path *path,
4516 const struct btrfs_key *new_key)
4518 struct extent_buffer *leaf;
4522 leaf = path->nodes[0];
4523 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4524 ret = setup_leaf_for_split(trans, root, path,
4525 item_size + sizeof(struct btrfs_item));
4530 setup_items_for_insert(root, path, new_key, &item_size,
4531 item_size, item_size +
4532 sizeof(struct btrfs_item), 1);
4533 leaf = path->nodes[0];
4534 memcpy_extent_buffer(leaf,
4535 btrfs_item_ptr_offset(leaf, path->slots[0]),
4536 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4542 * make the item pointed to by the path smaller. new_size indicates
4543 * how small to make it, and from_end tells us if we just chop bytes
4544 * off the end of the item or if we shift the item to chop bytes off
4547 void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end)
4550 struct extent_buffer *leaf;
4551 struct btrfs_item *item;
4553 unsigned int data_end;
4554 unsigned int old_data_start;
4555 unsigned int old_size;
4556 unsigned int size_diff;
4558 struct btrfs_map_token token;
4560 leaf = path->nodes[0];
4561 slot = path->slots[0];
4563 old_size = btrfs_item_size_nr(leaf, slot);
4564 if (old_size == new_size)
4567 nritems = btrfs_header_nritems(leaf);
4568 data_end = leaf_data_end(leaf);
4570 old_data_start = btrfs_item_offset_nr(leaf, slot);
4572 size_diff = old_size - new_size;
4575 BUG_ON(slot >= nritems);
4578 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4580 /* first correct the data pointers */
4581 btrfs_init_map_token(&token, leaf);
4582 for (i = slot; i < nritems; i++) {
4584 item = btrfs_item_nr(i);
4586 ioff = btrfs_token_item_offset(leaf, item, &token);
4587 btrfs_set_token_item_offset(leaf, item,
4588 ioff + size_diff, &token);
4591 /* shift the data */
4593 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4594 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4595 data_end, old_data_start + new_size - data_end);
4597 struct btrfs_disk_key disk_key;
4600 btrfs_item_key(leaf, &disk_key, slot);
4602 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4604 struct btrfs_file_extent_item *fi;
4606 fi = btrfs_item_ptr(leaf, slot,
4607 struct btrfs_file_extent_item);
4608 fi = (struct btrfs_file_extent_item *)(
4609 (unsigned long)fi - size_diff);
4611 if (btrfs_file_extent_type(leaf, fi) ==
4612 BTRFS_FILE_EXTENT_INLINE) {
4613 ptr = btrfs_item_ptr_offset(leaf, slot);
4614 memmove_extent_buffer(leaf, ptr,
4616 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4620 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4621 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4622 data_end, old_data_start - data_end);
4624 offset = btrfs_disk_key_offset(&disk_key);
4625 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4626 btrfs_set_item_key(leaf, &disk_key, slot);
4628 fixup_low_keys(path, &disk_key, 1);
4631 item = btrfs_item_nr(slot);
4632 btrfs_set_item_size(leaf, item, new_size);
4633 btrfs_mark_buffer_dirty(leaf);
4635 if (btrfs_leaf_free_space(leaf) < 0) {
4636 btrfs_print_leaf(leaf);
4642 * make the item pointed to by the path bigger, data_size is the added size.
4644 void btrfs_extend_item(struct btrfs_path *path, u32 data_size)
4647 struct extent_buffer *leaf;
4648 struct btrfs_item *item;
4650 unsigned int data_end;
4651 unsigned int old_data;
4652 unsigned int old_size;
4654 struct btrfs_map_token token;
4656 leaf = path->nodes[0];
4658 nritems = btrfs_header_nritems(leaf);
4659 data_end = leaf_data_end(leaf);
4661 if (btrfs_leaf_free_space(leaf) < data_size) {
4662 btrfs_print_leaf(leaf);
4665 slot = path->slots[0];
4666 old_data = btrfs_item_end_nr(leaf, slot);
4669 if (slot >= nritems) {
4670 btrfs_print_leaf(leaf);
4671 btrfs_crit(leaf->fs_info, "slot %d too large, nritems %d",
4677 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4679 /* first correct the data pointers */
4680 btrfs_init_map_token(&token, leaf);
4681 for (i = slot; i < nritems; i++) {
4683 item = btrfs_item_nr(i);
4685 ioff = btrfs_token_item_offset(leaf, item, &token);
4686 btrfs_set_token_item_offset(leaf, item,
4687 ioff - data_size, &token);
4690 /* shift the data */
4691 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4692 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4693 data_end, old_data - data_end);
4695 data_end = old_data;
4696 old_size = btrfs_item_size_nr(leaf, slot);
4697 item = btrfs_item_nr(slot);
4698 btrfs_set_item_size(leaf, item, old_size + data_size);
4699 btrfs_mark_buffer_dirty(leaf);
4701 if (btrfs_leaf_free_space(leaf) < 0) {
4702 btrfs_print_leaf(leaf);
4708 * this is a helper for btrfs_insert_empty_items, the main goal here is
4709 * to save stack depth by doing the bulk of the work in a function
4710 * that doesn't call btrfs_search_slot
4712 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4713 const struct btrfs_key *cpu_key, u32 *data_size,
4714 u32 total_data, u32 total_size, int nr)
4716 struct btrfs_fs_info *fs_info = root->fs_info;
4717 struct btrfs_item *item;
4720 unsigned int data_end;
4721 struct btrfs_disk_key disk_key;
4722 struct extent_buffer *leaf;
4724 struct btrfs_map_token token;
4726 if (path->slots[0] == 0) {
4727 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4728 fixup_low_keys(path, &disk_key, 1);
4730 btrfs_unlock_up_safe(path, 1);
4732 leaf = path->nodes[0];
4733 slot = path->slots[0];
4735 nritems = btrfs_header_nritems(leaf);
4736 data_end = leaf_data_end(leaf);
4738 if (btrfs_leaf_free_space(leaf) < total_size) {
4739 btrfs_print_leaf(leaf);
4740 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4741 total_size, btrfs_leaf_free_space(leaf));
4745 btrfs_init_map_token(&token, leaf);
4746 if (slot != nritems) {
4747 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4749 if (old_data < data_end) {
4750 btrfs_print_leaf(leaf);
4751 btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4752 slot, old_data, data_end);
4756 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4758 /* first correct the data pointers */
4759 for (i = slot; i < nritems; i++) {
4762 item = btrfs_item_nr(i);
4763 ioff = btrfs_token_item_offset(leaf, item, &token);
4764 btrfs_set_token_item_offset(leaf, item,
4765 ioff - total_data, &token);
4767 /* shift the items */
4768 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4769 btrfs_item_nr_offset(slot),
4770 (nritems - slot) * sizeof(struct btrfs_item));
4772 /* shift the data */
4773 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4774 data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4775 data_end, old_data - data_end);
4776 data_end = old_data;
4779 /* setup the item for the new data */
4780 for (i = 0; i < nr; i++) {
4781 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4782 btrfs_set_item_key(leaf, &disk_key, slot + i);
4783 item = btrfs_item_nr(slot + i);
4784 btrfs_set_token_item_offset(leaf, item,
4785 data_end - data_size[i], &token);
4786 data_end -= data_size[i];
4787 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4790 btrfs_set_header_nritems(leaf, nritems + nr);
4791 btrfs_mark_buffer_dirty(leaf);
4793 if (btrfs_leaf_free_space(leaf) < 0) {
4794 btrfs_print_leaf(leaf);
4800 * Given a key and some data, insert items into the tree.
4801 * This does all the path init required, making room in the tree if needed.
4803 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4804 struct btrfs_root *root,
4805 struct btrfs_path *path,
4806 const struct btrfs_key *cpu_key, u32 *data_size,
4815 for (i = 0; i < nr; i++)
4816 total_data += data_size[i];
4818 total_size = total_data + (nr * sizeof(struct btrfs_item));
4819 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4825 slot = path->slots[0];
4828 setup_items_for_insert(root, path, cpu_key, data_size,
4829 total_data, total_size, nr);
4834 * Given a key and some data, insert an item into the tree.
4835 * This does all the path init required, making room in the tree if needed.
4837 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4838 const struct btrfs_key *cpu_key, void *data,
4842 struct btrfs_path *path;
4843 struct extent_buffer *leaf;
4846 path = btrfs_alloc_path();
4849 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4851 leaf = path->nodes[0];
4852 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4853 write_extent_buffer(leaf, data, ptr, data_size);
4854 btrfs_mark_buffer_dirty(leaf);
4856 btrfs_free_path(path);
4861 * delete the pointer from a given node.
4863 * the tree should have been previously balanced so the deletion does not
4866 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4867 int level, int slot)
4869 struct extent_buffer *parent = path->nodes[level];
4873 nritems = btrfs_header_nritems(parent);
4874 if (slot != nritems - 1) {
4876 ret = tree_mod_log_insert_move(parent, slot, slot + 1,
4877 nritems - slot - 1);
4880 memmove_extent_buffer(parent,
4881 btrfs_node_key_ptr_offset(slot),
4882 btrfs_node_key_ptr_offset(slot + 1),
4883 sizeof(struct btrfs_key_ptr) *
4884 (nritems - slot - 1));
4886 ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE,
4892 btrfs_set_header_nritems(parent, nritems);
4893 if (nritems == 0 && parent == root->node) {
4894 BUG_ON(btrfs_header_level(root->node) != 1);
4895 /* just turn the root into a leaf and break */
4896 btrfs_set_header_level(root->node, 0);
4897 } else if (slot == 0) {
4898 struct btrfs_disk_key disk_key;
4900 btrfs_node_key(parent, &disk_key, 0);
4901 fixup_low_keys(path, &disk_key, level + 1);
4903 btrfs_mark_buffer_dirty(parent);
4907 * a helper function to delete the leaf pointed to by path->slots[1] and
4910 * This deletes the pointer in path->nodes[1] and frees the leaf
4911 * block extent. zero is returned if it all worked out, < 0 otherwise.
4913 * The path must have already been setup for deleting the leaf, including
4914 * all the proper balancing. path->nodes[1] must be locked.
4916 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4917 struct btrfs_root *root,
4918 struct btrfs_path *path,
4919 struct extent_buffer *leaf)
4921 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4922 del_ptr(root, path, 1, path->slots[1]);
4925 * btrfs_free_extent is expensive, we want to make sure we
4926 * aren't holding any locks when we call it
4928 btrfs_unlock_up_safe(path, 0);
4930 root_sub_used(root, leaf->len);
4932 atomic_inc(&leaf->refs);
4933 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4934 free_extent_buffer_stale(leaf);
4937 * delete the item at the leaf level in path. If that empties
4938 * the leaf, remove it from the tree
4940 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4941 struct btrfs_path *path, int slot, int nr)
4943 struct btrfs_fs_info *fs_info = root->fs_info;
4944 struct extent_buffer *leaf;
4945 struct btrfs_item *item;
4953 leaf = path->nodes[0];
4954 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4956 for (i = 0; i < nr; i++)
4957 dsize += btrfs_item_size_nr(leaf, slot + i);
4959 nritems = btrfs_header_nritems(leaf);
4961 if (slot + nr != nritems) {
4962 int data_end = leaf_data_end(leaf);
4963 struct btrfs_map_token token;
4965 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4967 BTRFS_LEAF_DATA_OFFSET + data_end,
4968 last_off - data_end);
4970 btrfs_init_map_token(&token, leaf);
4971 for (i = slot + nr; i < nritems; i++) {
4974 item = btrfs_item_nr(i);
4975 ioff = btrfs_token_item_offset(leaf, item, &token);
4976 btrfs_set_token_item_offset(leaf, item,
4977 ioff + dsize, &token);
4980 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4981 btrfs_item_nr_offset(slot + nr),
4982 sizeof(struct btrfs_item) *
4983 (nritems - slot - nr));
4985 btrfs_set_header_nritems(leaf, nritems - nr);
4988 /* delete the leaf if we've emptied it */
4990 if (leaf == root->node) {
4991 btrfs_set_header_level(leaf, 0);
4993 btrfs_set_path_blocking(path);
4994 btrfs_clean_tree_block(leaf);
4995 btrfs_del_leaf(trans, root, path, leaf);
4998 int used = leaf_space_used(leaf, 0, nritems);
5000 struct btrfs_disk_key disk_key;
5002 btrfs_item_key(leaf, &disk_key, 0);
5003 fixup_low_keys(path, &disk_key, 1);
5006 /* delete the leaf if it is mostly empty */
5007 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
5008 /* push_leaf_left fixes the path.
5009 * make sure the path still points to our leaf
5010 * for possible call to del_ptr below
5012 slot = path->slots[1];
5013 atomic_inc(&leaf->refs);
5015 btrfs_set_path_blocking(path);
5016 wret = push_leaf_left(trans, root, path, 1, 1,
5018 if (wret < 0 && wret != -ENOSPC)
5021 if (path->nodes[0] == leaf &&
5022 btrfs_header_nritems(leaf)) {
5023 wret = push_leaf_right(trans, root, path, 1,
5025 if (wret < 0 && wret != -ENOSPC)
5029 if (btrfs_header_nritems(leaf) == 0) {
5030 path->slots[1] = slot;
5031 btrfs_del_leaf(trans, root, path, leaf);
5032 free_extent_buffer(leaf);
5035 /* if we're still in the path, make sure
5036 * we're dirty. Otherwise, one of the
5037 * push_leaf functions must have already
5038 * dirtied this buffer
5040 if (path->nodes[0] == leaf)
5041 btrfs_mark_buffer_dirty(leaf);
5042 free_extent_buffer(leaf);
5045 btrfs_mark_buffer_dirty(leaf);
5052 * search the tree again to find a leaf with lesser keys
5053 * returns 0 if it found something or 1 if there are no lesser leaves.
5054 * returns < 0 on io errors.
5056 * This may release the path, and so you may lose any locks held at the
5059 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5061 struct btrfs_key key;
5062 struct btrfs_disk_key found_key;
5065 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5067 if (key.offset > 0) {
5069 } else if (key.type > 0) {
5071 key.offset = (u64)-1;
5072 } else if (key.objectid > 0) {
5075 key.offset = (u64)-1;
5080 btrfs_release_path(path);
5081 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5084 btrfs_item_key(path->nodes[0], &found_key, 0);
5085 ret = comp_keys(&found_key, &key);
5087 * We might have had an item with the previous key in the tree right
5088 * before we released our path. And after we released our path, that
5089 * item might have been pushed to the first slot (0) of the leaf we
5090 * were holding due to a tree balance. Alternatively, an item with the
5091 * previous key can exist as the only element of a leaf (big fat item).
5092 * Therefore account for these 2 cases, so that our callers (like
5093 * btrfs_previous_item) don't miss an existing item with a key matching
5094 * the previous key we computed above.
5102 * A helper function to walk down the tree starting at min_key, and looking
5103 * for nodes or leaves that are have a minimum transaction id.
5104 * This is used by the btree defrag code, and tree logging
5106 * This does not cow, but it does stuff the starting key it finds back
5107 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5108 * key and get a writable path.
5110 * This honors path->lowest_level to prevent descent past a given level
5113 * min_trans indicates the oldest transaction that you are interested
5114 * in walking through. Any nodes or leaves older than min_trans are
5115 * skipped over (without reading them).
5117 * returns zero if something useful was found, < 0 on error and 1 if there
5118 * was nothing in the tree that matched the search criteria.
5120 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5121 struct btrfs_path *path,
5124 struct extent_buffer *cur;
5125 struct btrfs_key found_key;
5131 int keep_locks = path->keep_locks;
5133 path->keep_locks = 1;
5135 cur = btrfs_read_lock_root_node(root);
5136 level = btrfs_header_level(cur);
5137 WARN_ON(path->nodes[level]);
5138 path->nodes[level] = cur;
5139 path->locks[level] = BTRFS_READ_LOCK;
5141 if (btrfs_header_generation(cur) < min_trans) {
5146 nritems = btrfs_header_nritems(cur);
5147 level = btrfs_header_level(cur);
5148 sret = btrfs_bin_search(cur, min_key, level, &slot);
5154 /* at the lowest level, we're done, setup the path and exit */
5155 if (level == path->lowest_level) {
5156 if (slot >= nritems)
5159 path->slots[level] = slot;
5160 btrfs_item_key_to_cpu(cur, &found_key, slot);
5163 if (sret && slot > 0)
5166 * check this node pointer against the min_trans parameters.
5167 * If it is too old, old, skip to the next one.
5169 while (slot < nritems) {
5172 gen = btrfs_node_ptr_generation(cur, slot);
5173 if (gen < min_trans) {
5181 * we didn't find a candidate key in this node, walk forward
5182 * and find another one
5184 if (slot >= nritems) {
5185 path->slots[level] = slot;
5186 btrfs_set_path_blocking(path);
5187 sret = btrfs_find_next_key(root, path, min_key, level,
5190 btrfs_release_path(path);
5196 /* save our key for returning back */
5197 btrfs_node_key_to_cpu(cur, &found_key, slot);
5198 path->slots[level] = slot;
5199 if (level == path->lowest_level) {
5203 btrfs_set_path_blocking(path);
5204 cur = btrfs_read_node_slot(cur, slot);
5210 btrfs_tree_read_lock(cur);
5212 path->locks[level - 1] = BTRFS_READ_LOCK;
5213 path->nodes[level - 1] = cur;
5214 unlock_up(path, level, 1, 0, NULL);
5217 path->keep_locks = keep_locks;
5219 btrfs_unlock_up_safe(path, path->lowest_level + 1);
5220 btrfs_set_path_blocking(path);
5221 memcpy(min_key, &found_key, sizeof(found_key));
5227 * this is similar to btrfs_next_leaf, but does not try to preserve
5228 * and fixup the path. It looks for and returns the next key in the
5229 * tree based on the current path and the min_trans parameters.
5231 * 0 is returned if another key is found, < 0 if there are any errors
5232 * and 1 is returned if there are no higher keys in the tree
5234 * path->keep_locks should be set to 1 on the search made before
5235 * calling this function.
5237 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5238 struct btrfs_key *key, int level, u64 min_trans)
5241 struct extent_buffer *c;
5243 WARN_ON(!path->keep_locks && !path->skip_locking);
5244 while (level < BTRFS_MAX_LEVEL) {
5245 if (!path->nodes[level])
5248 slot = path->slots[level] + 1;
5249 c = path->nodes[level];
5251 if (slot >= btrfs_header_nritems(c)) {
5254 struct btrfs_key cur_key;
5255 if (level + 1 >= BTRFS_MAX_LEVEL ||
5256 !path->nodes[level + 1])
5259 if (path->locks[level + 1] || path->skip_locking) {
5264 slot = btrfs_header_nritems(c) - 1;
5266 btrfs_item_key_to_cpu(c, &cur_key, slot);
5268 btrfs_node_key_to_cpu(c, &cur_key, slot);
5270 orig_lowest = path->lowest_level;
5271 btrfs_release_path(path);
5272 path->lowest_level = level;
5273 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5275 path->lowest_level = orig_lowest;
5279 c = path->nodes[level];
5280 slot = path->slots[level];
5287 btrfs_item_key_to_cpu(c, key, slot);
5289 u64 gen = btrfs_node_ptr_generation(c, slot);
5291 if (gen < min_trans) {
5295 btrfs_node_key_to_cpu(c, key, slot);
5303 * search the tree again to find a leaf with greater keys
5304 * returns 0 if it found something or 1 if there are no greater leaves.
5305 * returns < 0 on io errors.
5307 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5309 return btrfs_next_old_leaf(root, path, 0);
5312 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5317 struct extent_buffer *c;
5318 struct extent_buffer *next;
5319 struct btrfs_key key;
5322 int old_spinning = path->leave_spinning;
5323 int next_rw_lock = 0;
5325 nritems = btrfs_header_nritems(path->nodes[0]);
5329 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5334 btrfs_release_path(path);
5336 path->keep_locks = 1;
5337 path->leave_spinning = 1;
5340 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5342 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5343 path->keep_locks = 0;
5348 nritems = btrfs_header_nritems(path->nodes[0]);
5350 * by releasing the path above we dropped all our locks. A balance
5351 * could have added more items next to the key that used to be
5352 * at the very end of the block. So, check again here and
5353 * advance the path if there are now more items available.
5355 if (nritems > 0 && path->slots[0] < nritems - 1) {
5362 * So the above check misses one case:
5363 * - after releasing the path above, someone has removed the item that
5364 * used to be at the very end of the block, and balance between leafs
5365 * gets another one with bigger key.offset to replace it.
5367 * This one should be returned as well, or we can get leaf corruption
5368 * later(esp. in __btrfs_drop_extents()).
5370 * And a bit more explanation about this check,
5371 * with ret > 0, the key isn't found, the path points to the slot
5372 * where it should be inserted, so the path->slots[0] item must be the
5375 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5380 while (level < BTRFS_MAX_LEVEL) {
5381 if (!path->nodes[level]) {
5386 slot = path->slots[level] + 1;
5387 c = path->nodes[level];
5388 if (slot >= btrfs_header_nritems(c)) {
5390 if (level == BTRFS_MAX_LEVEL) {
5398 btrfs_tree_unlock_rw(next, next_rw_lock);
5399 free_extent_buffer(next);
5403 next_rw_lock = path->locks[level];
5404 ret = read_block_for_search(root, path, &next, level,
5410 btrfs_release_path(path);
5414 if (!path->skip_locking) {
5415 ret = btrfs_try_tree_read_lock(next);
5416 if (!ret && time_seq) {
5418 * If we don't get the lock, we may be racing
5419 * with push_leaf_left, holding that lock while
5420 * itself waiting for the leaf we've currently
5421 * locked. To solve this situation, we give up
5422 * on our lock and cycle.
5424 free_extent_buffer(next);
5425 btrfs_release_path(path);
5430 btrfs_set_path_blocking(path);
5431 btrfs_tree_read_lock(next);
5433 next_rw_lock = BTRFS_READ_LOCK;
5437 path->slots[level] = slot;
5440 c = path->nodes[level];
5441 if (path->locks[level])
5442 btrfs_tree_unlock_rw(c, path->locks[level]);
5444 free_extent_buffer(c);
5445 path->nodes[level] = next;
5446 path->slots[level] = 0;
5447 if (!path->skip_locking)
5448 path->locks[level] = next_rw_lock;
5452 ret = read_block_for_search(root, path, &next, level,
5458 btrfs_release_path(path);
5462 if (!path->skip_locking) {
5463 ret = btrfs_try_tree_read_lock(next);
5465 btrfs_set_path_blocking(path);
5466 btrfs_tree_read_lock(next);
5468 next_rw_lock = BTRFS_READ_LOCK;
5473 unlock_up(path, 0, 1, 0, NULL);
5474 path->leave_spinning = old_spinning;
5476 btrfs_set_path_blocking(path);
5482 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5483 * searching until it gets past min_objectid or finds an item of 'type'
5485 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5487 int btrfs_previous_item(struct btrfs_root *root,
5488 struct btrfs_path *path, u64 min_objectid,
5491 struct btrfs_key found_key;
5492 struct extent_buffer *leaf;
5497 if (path->slots[0] == 0) {
5498 btrfs_set_path_blocking(path);
5499 ret = btrfs_prev_leaf(root, path);
5505 leaf = path->nodes[0];
5506 nritems = btrfs_header_nritems(leaf);
5509 if (path->slots[0] == nritems)
5512 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5513 if (found_key.objectid < min_objectid)
5515 if (found_key.type == type)
5517 if (found_key.objectid == min_objectid &&
5518 found_key.type < type)
5525 * search in extent tree to find a previous Metadata/Data extent item with
5528 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5530 int btrfs_previous_extent_item(struct btrfs_root *root,
5531 struct btrfs_path *path, u64 min_objectid)
5533 struct btrfs_key found_key;
5534 struct extent_buffer *leaf;
5539 if (path->slots[0] == 0) {
5540 btrfs_set_path_blocking(path);
5541 ret = btrfs_prev_leaf(root, path);
5547 leaf = path->nodes[0];
5548 nritems = btrfs_header_nritems(leaf);
5551 if (path->slots[0] == nritems)
5554 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5555 if (found_key.objectid < min_objectid)
5557 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5558 found_key.type == BTRFS_METADATA_ITEM_KEY)
5560 if (found_key.objectid == min_objectid &&
5561 found_key.type < BTRFS_EXTENT_ITEM_KEY)