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 btrfs_fs_info *fs_info,
25 struct extent_buffer *dst,
26 struct extent_buffer *src, int empty);
27 static int balance_node_right(struct btrfs_trans_handle *trans,
28 struct btrfs_fs_info *fs_info,
29 struct extent_buffer *dst_buf,
30 struct extent_buffer *src_buf);
31 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
34 struct btrfs_path *btrfs_alloc_path(void)
36 return kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
40 * set all locked nodes in the path to blocking locks. This should
41 * be done before scheduling
43 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
46 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
47 if (!p->nodes[i] || !p->locks[i])
50 * If we currently have a spinning reader or writer lock this
51 * will bump the count of blocking holders and drop the
54 if (p->locks[i] == BTRFS_READ_LOCK) {
55 btrfs_set_lock_blocking_read(p->nodes[i]);
56 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
57 } else if (p->locks[i] == BTRFS_WRITE_LOCK) {
58 btrfs_set_lock_blocking_write(p->nodes[i]);
59 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
64 /* this also releases the path */
65 void btrfs_free_path(struct btrfs_path *p)
69 btrfs_release_path(p);
70 kmem_cache_free(btrfs_path_cachep, p);
74 * path release drops references on the extent buffers in the path
75 * and it drops any locks held by this path
77 * It is safe to call this on paths that no locks or extent buffers held.
79 noinline void btrfs_release_path(struct btrfs_path *p)
83 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
88 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
91 free_extent_buffer(p->nodes[i]);
97 * safely gets a reference on the root node of a tree. A lock
98 * is not taken, so a concurrent writer may put a different node
99 * at the root of the tree. See btrfs_lock_root_node for the
102 * The extent buffer returned by this has a reference taken, so
103 * it won't disappear. It may stop being the root of the tree
104 * at any time because there are no locks held.
106 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
108 struct extent_buffer *eb;
112 eb = rcu_dereference(root->node);
115 * RCU really hurts here, we could free up the root node because
116 * it was COWed but we may not get the new root node yet so do
117 * the inc_not_zero dance and if it doesn't work then
118 * synchronize_rcu and try again.
120 if (atomic_inc_not_zero(&eb->refs)) {
130 /* loop around taking references on and locking the root node of the
131 * tree until you end up with a lock on the root. A locked buffer
132 * is returned, with a reference held.
134 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
136 struct extent_buffer *eb;
139 eb = btrfs_root_node(root);
141 if (eb == root->node)
143 btrfs_tree_unlock(eb);
144 free_extent_buffer(eb);
149 /* loop around taking references on and locking the root node of the
150 * tree until you end up with a lock on the root. A locked buffer
151 * is returned, with a reference held.
153 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
155 struct extent_buffer *eb;
158 eb = btrfs_root_node(root);
159 btrfs_tree_read_lock(eb);
160 if (eb == root->node)
162 btrfs_tree_read_unlock(eb);
163 free_extent_buffer(eb);
168 /* cowonly root (everything not a reference counted cow subvolume), just get
169 * put onto a simple dirty list. transaction.c walks this to make sure they
170 * get properly updated on disk.
172 static void add_root_to_dirty_list(struct btrfs_root *root)
174 struct btrfs_fs_info *fs_info = root->fs_info;
176 if (test_bit(BTRFS_ROOT_DIRTY, &root->state) ||
177 !test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state))
180 spin_lock(&fs_info->trans_lock);
181 if (!test_and_set_bit(BTRFS_ROOT_DIRTY, &root->state)) {
182 /* Want the extent tree to be the last on the list */
183 if (root->root_key.objectid == BTRFS_EXTENT_TREE_OBJECTID)
184 list_move_tail(&root->dirty_list,
185 &fs_info->dirty_cowonly_roots);
187 list_move(&root->dirty_list,
188 &fs_info->dirty_cowonly_roots);
190 spin_unlock(&fs_info->trans_lock);
194 * used by snapshot creation to make a copy of a root for a tree with
195 * a given objectid. The buffer with the new root node is returned in
196 * cow_ret, and this func returns zero on success or a negative error code.
198 int btrfs_copy_root(struct btrfs_trans_handle *trans,
199 struct btrfs_root *root,
200 struct extent_buffer *buf,
201 struct extent_buffer **cow_ret, u64 new_root_objectid)
203 struct btrfs_fs_info *fs_info = root->fs_info;
204 struct extent_buffer *cow;
207 struct btrfs_disk_key disk_key;
209 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
210 trans->transid != fs_info->running_transaction->transid);
211 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
212 trans->transid != root->last_trans);
214 level = btrfs_header_level(buf);
216 btrfs_item_key(buf, &disk_key, 0);
218 btrfs_node_key(buf, &disk_key, 0);
220 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
221 &disk_key, level, buf->start, 0);
225 copy_extent_buffer_full(cow, buf);
226 btrfs_set_header_bytenr(cow, cow->start);
227 btrfs_set_header_generation(cow, trans->transid);
228 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
229 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
230 BTRFS_HEADER_FLAG_RELOC);
231 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
232 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
234 btrfs_set_header_owner(cow, new_root_objectid);
236 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
238 WARN_ON(btrfs_header_generation(buf) > trans->transid);
239 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
240 ret = btrfs_inc_ref(trans, root, cow, 1);
242 ret = btrfs_inc_ref(trans, root, cow, 0);
247 btrfs_mark_buffer_dirty(cow);
256 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
257 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
259 MOD_LOG_ROOT_REPLACE,
262 struct tree_mod_root {
267 struct tree_mod_elem {
273 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
276 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
279 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
280 struct btrfs_disk_key key;
283 /* this is used for op == MOD_LOG_MOVE_KEYS */
289 /* this is used for op == MOD_LOG_ROOT_REPLACE */
290 struct tree_mod_root old_root;
294 * Pull a new tree mod seq number for our operation.
296 static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
298 return atomic64_inc_return(&fs_info->tree_mod_seq);
302 * This adds a new blocker to the tree mod log's blocker list if the @elem
303 * passed does not already have a sequence number set. So when a caller expects
304 * to record tree modifications, it should ensure to set elem->seq to zero
305 * before calling btrfs_get_tree_mod_seq.
306 * Returns a fresh, unused tree log modification sequence number, even if no new
309 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
310 struct seq_list *elem)
312 write_lock(&fs_info->tree_mod_log_lock);
313 spin_lock(&fs_info->tree_mod_seq_lock);
315 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
316 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
318 spin_unlock(&fs_info->tree_mod_seq_lock);
319 write_unlock(&fs_info->tree_mod_log_lock);
324 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
325 struct seq_list *elem)
327 struct rb_root *tm_root;
328 struct rb_node *node;
329 struct rb_node *next;
330 struct seq_list *cur_elem;
331 struct tree_mod_elem *tm;
332 u64 min_seq = (u64)-1;
333 u64 seq_putting = elem->seq;
338 spin_lock(&fs_info->tree_mod_seq_lock);
339 list_del(&elem->list);
342 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
343 if (cur_elem->seq < min_seq) {
344 if (seq_putting > cur_elem->seq) {
346 * blocker with lower sequence number exists, we
347 * cannot remove anything from the log
349 spin_unlock(&fs_info->tree_mod_seq_lock);
352 min_seq = cur_elem->seq;
355 spin_unlock(&fs_info->tree_mod_seq_lock);
358 * anything that's lower than the lowest existing (read: blocked)
359 * sequence number can be removed from the tree.
361 write_lock(&fs_info->tree_mod_log_lock);
362 tm_root = &fs_info->tree_mod_log;
363 for (node = rb_first(tm_root); node; node = next) {
364 next = rb_next(node);
365 tm = rb_entry(node, struct tree_mod_elem, node);
366 if (tm->seq > min_seq)
368 rb_erase(node, tm_root);
371 write_unlock(&fs_info->tree_mod_log_lock);
375 * key order of the log:
376 * node/leaf start address -> sequence
378 * The 'start address' is the logical address of the *new* root node
379 * for root replace operations, or the logical address of the affected
380 * block for all other operations.
382 * Note: must be called with write lock for fs_info::tree_mod_log_lock.
385 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
387 struct rb_root *tm_root;
388 struct rb_node **new;
389 struct rb_node *parent = NULL;
390 struct tree_mod_elem *cur;
392 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
394 tm_root = &fs_info->tree_mod_log;
395 new = &tm_root->rb_node;
397 cur = rb_entry(*new, struct tree_mod_elem, node);
399 if (cur->logical < tm->logical)
400 new = &((*new)->rb_left);
401 else if (cur->logical > tm->logical)
402 new = &((*new)->rb_right);
403 else if (cur->seq < tm->seq)
404 new = &((*new)->rb_left);
405 else if (cur->seq > tm->seq)
406 new = &((*new)->rb_right);
411 rb_link_node(&tm->node, parent, new);
412 rb_insert_color(&tm->node, tm_root);
417 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
418 * returns zero with the tree_mod_log_lock acquired. The caller must hold
419 * this until all tree mod log insertions are recorded in the rb tree and then
420 * write unlock fs_info::tree_mod_log_lock.
422 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
423 struct extent_buffer *eb) {
425 if (list_empty(&(fs_info)->tree_mod_seq_list))
427 if (eb && btrfs_header_level(eb) == 0)
430 write_lock(&fs_info->tree_mod_log_lock);
431 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
432 write_unlock(&fs_info->tree_mod_log_lock);
439 /* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
440 static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
441 struct extent_buffer *eb)
444 if (list_empty(&(fs_info)->tree_mod_seq_list))
446 if (eb && btrfs_header_level(eb) == 0)
452 static struct tree_mod_elem *
453 alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
454 enum mod_log_op op, gfp_t flags)
456 struct tree_mod_elem *tm;
458 tm = kzalloc(sizeof(*tm), flags);
462 tm->logical = eb->start;
463 if (op != MOD_LOG_KEY_ADD) {
464 btrfs_node_key(eb, &tm->key, slot);
465 tm->blockptr = btrfs_node_blockptr(eb, slot);
469 tm->generation = btrfs_node_ptr_generation(eb, slot);
470 RB_CLEAR_NODE(&tm->node);
475 static noinline int tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
476 enum mod_log_op op, gfp_t flags)
478 struct tree_mod_elem *tm;
481 if (!tree_mod_need_log(eb->fs_info, eb))
484 tm = alloc_tree_mod_elem(eb, slot, op, flags);
488 if (tree_mod_dont_log(eb->fs_info, eb)) {
493 ret = __tree_mod_log_insert(eb->fs_info, tm);
494 write_unlock(&eb->fs_info->tree_mod_log_lock);
501 static noinline int tree_mod_log_insert_move(struct extent_buffer *eb,
502 int dst_slot, int src_slot, int nr_items)
504 struct tree_mod_elem *tm = NULL;
505 struct tree_mod_elem **tm_list = NULL;
510 if (!tree_mod_need_log(eb->fs_info, eb))
513 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
517 tm = kzalloc(sizeof(*tm), GFP_NOFS);
523 tm->logical = eb->start;
525 tm->move.dst_slot = dst_slot;
526 tm->move.nr_items = nr_items;
527 tm->op = MOD_LOG_MOVE_KEYS;
529 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
530 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
531 MOD_LOG_KEY_REMOVE_WHILE_MOVING, GFP_NOFS);
538 if (tree_mod_dont_log(eb->fs_info, eb))
543 * When we override something during the move, we log these removals.
544 * This can only happen when we move towards the beginning of the
545 * buffer, i.e. dst_slot < src_slot.
547 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
548 ret = __tree_mod_log_insert(eb->fs_info, tm_list[i]);
553 ret = __tree_mod_log_insert(eb->fs_info, tm);
556 write_unlock(&eb->fs_info->tree_mod_log_lock);
561 for (i = 0; i < nr_items; i++) {
562 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
563 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
567 write_unlock(&eb->fs_info->tree_mod_log_lock);
575 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
576 struct tree_mod_elem **tm_list,
582 for (i = nritems - 1; i >= 0; i--) {
583 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
585 for (j = nritems - 1; j > i; j--)
586 rb_erase(&tm_list[j]->node,
587 &fs_info->tree_mod_log);
595 static noinline int tree_mod_log_insert_root(struct extent_buffer *old_root,
596 struct extent_buffer *new_root, int log_removal)
598 struct btrfs_fs_info *fs_info = old_root->fs_info;
599 struct tree_mod_elem *tm = NULL;
600 struct tree_mod_elem **tm_list = NULL;
605 if (!tree_mod_need_log(fs_info, NULL))
608 if (log_removal && btrfs_header_level(old_root) > 0) {
609 nritems = btrfs_header_nritems(old_root);
610 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
616 for (i = 0; i < nritems; i++) {
617 tm_list[i] = alloc_tree_mod_elem(old_root, i,
618 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
626 tm = kzalloc(sizeof(*tm), GFP_NOFS);
632 tm->logical = new_root->start;
633 tm->old_root.logical = old_root->start;
634 tm->old_root.level = btrfs_header_level(old_root);
635 tm->generation = btrfs_header_generation(old_root);
636 tm->op = MOD_LOG_ROOT_REPLACE;
638 if (tree_mod_dont_log(fs_info, NULL))
642 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
644 ret = __tree_mod_log_insert(fs_info, tm);
646 write_unlock(&fs_info->tree_mod_log_lock);
655 for (i = 0; i < nritems; i++)
664 static struct tree_mod_elem *
665 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
668 struct rb_root *tm_root;
669 struct rb_node *node;
670 struct tree_mod_elem *cur = NULL;
671 struct tree_mod_elem *found = NULL;
673 read_lock(&fs_info->tree_mod_log_lock);
674 tm_root = &fs_info->tree_mod_log;
675 node = tm_root->rb_node;
677 cur = rb_entry(node, struct tree_mod_elem, node);
678 if (cur->logical < start) {
679 node = node->rb_left;
680 } else if (cur->logical > start) {
681 node = node->rb_right;
682 } else if (cur->seq < min_seq) {
683 node = node->rb_left;
684 } else if (!smallest) {
685 /* we want the node with the highest seq */
687 BUG_ON(found->seq > cur->seq);
689 node = node->rb_left;
690 } else if (cur->seq > min_seq) {
691 /* we want the node with the smallest seq */
693 BUG_ON(found->seq < cur->seq);
695 node = node->rb_right;
701 read_unlock(&fs_info->tree_mod_log_lock);
707 * this returns the element from the log with the smallest time sequence
708 * value that's in the log (the oldest log item). any element with a time
709 * sequence lower than min_seq will be ignored.
711 static struct tree_mod_elem *
712 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
715 return __tree_mod_log_search(fs_info, start, min_seq, 1);
719 * this returns the element from the log with the largest time sequence
720 * value that's in the log (the most recent log item). any element with
721 * a time sequence lower than min_seq will be ignored.
723 static struct tree_mod_elem *
724 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
726 return __tree_mod_log_search(fs_info, start, min_seq, 0);
729 static noinline int tree_mod_log_eb_copy(struct extent_buffer *dst,
730 struct extent_buffer *src, unsigned long dst_offset,
731 unsigned long src_offset, int nr_items)
733 struct btrfs_fs_info *fs_info = dst->fs_info;
735 struct tree_mod_elem **tm_list = NULL;
736 struct tree_mod_elem **tm_list_add, **tm_list_rem;
740 if (!tree_mod_need_log(fs_info, NULL))
743 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
746 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
751 tm_list_add = tm_list;
752 tm_list_rem = tm_list + nr_items;
753 for (i = 0; i < nr_items; i++) {
754 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
755 MOD_LOG_KEY_REMOVE, GFP_NOFS);
756 if (!tm_list_rem[i]) {
761 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
762 MOD_LOG_KEY_ADD, GFP_NOFS);
763 if (!tm_list_add[i]) {
769 if (tree_mod_dont_log(fs_info, NULL))
773 for (i = 0; i < nr_items; i++) {
774 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
777 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
782 write_unlock(&fs_info->tree_mod_log_lock);
788 for (i = 0; i < nr_items * 2; i++) {
789 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
790 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
794 write_unlock(&fs_info->tree_mod_log_lock);
800 static noinline int tree_mod_log_free_eb(struct extent_buffer *eb)
802 struct tree_mod_elem **tm_list = NULL;
807 if (btrfs_header_level(eb) == 0)
810 if (!tree_mod_need_log(eb->fs_info, NULL))
813 nritems = btrfs_header_nritems(eb);
814 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
818 for (i = 0; i < nritems; i++) {
819 tm_list[i] = alloc_tree_mod_elem(eb, i,
820 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
827 if (tree_mod_dont_log(eb->fs_info, eb))
830 ret = __tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
831 write_unlock(&eb->fs_info->tree_mod_log_lock);
839 for (i = 0; i < nritems; i++)
847 * check if the tree block can be shared by multiple trees
849 int btrfs_block_can_be_shared(struct btrfs_root *root,
850 struct extent_buffer *buf)
853 * Tree blocks not in reference counted trees and tree roots
854 * are never shared. If a block was allocated after the last
855 * snapshot and the block was not allocated by tree relocation,
856 * we know the block is not shared.
858 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
859 buf != root->node && buf != root->commit_root &&
860 (btrfs_header_generation(buf) <=
861 btrfs_root_last_snapshot(&root->root_item) ||
862 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
868 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
869 struct btrfs_root *root,
870 struct extent_buffer *buf,
871 struct extent_buffer *cow,
874 struct btrfs_fs_info *fs_info = root->fs_info;
882 * Backrefs update rules:
884 * Always use full backrefs for extent pointers in tree block
885 * allocated by tree relocation.
887 * If a shared tree block is no longer referenced by its owner
888 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
889 * use full backrefs for extent pointers in tree block.
891 * If a tree block is been relocating
892 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
893 * use full backrefs for extent pointers in tree block.
894 * The reason for this is some operations (such as drop tree)
895 * are only allowed for blocks use full backrefs.
898 if (btrfs_block_can_be_shared(root, buf)) {
899 ret = btrfs_lookup_extent_info(trans, fs_info, buf->start,
900 btrfs_header_level(buf), 1,
906 btrfs_handle_fs_error(fs_info, ret, NULL);
911 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
912 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
913 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
918 owner = btrfs_header_owner(buf);
919 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
920 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
923 if ((owner == root->root_key.objectid ||
924 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
925 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
926 ret = btrfs_inc_ref(trans, root, buf, 1);
930 if (root->root_key.objectid ==
931 BTRFS_TREE_RELOC_OBJECTID) {
932 ret = btrfs_dec_ref(trans, root, buf, 0);
935 ret = btrfs_inc_ref(trans, root, cow, 1);
939 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
942 if (root->root_key.objectid ==
943 BTRFS_TREE_RELOC_OBJECTID)
944 ret = btrfs_inc_ref(trans, root, cow, 1);
946 ret = btrfs_inc_ref(trans, root, cow, 0);
950 if (new_flags != 0) {
951 int level = btrfs_header_level(buf);
953 ret = btrfs_set_disk_extent_flags(trans, fs_info,
956 new_flags, level, 0);
961 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
962 if (root->root_key.objectid ==
963 BTRFS_TREE_RELOC_OBJECTID)
964 ret = btrfs_inc_ref(trans, root, cow, 1);
966 ret = btrfs_inc_ref(trans, root, cow, 0);
969 ret = btrfs_dec_ref(trans, root, buf, 1);
973 btrfs_clean_tree_block(buf);
979 static struct extent_buffer *alloc_tree_block_no_bg_flush(
980 struct btrfs_trans_handle *trans,
981 struct btrfs_root *root,
983 const struct btrfs_disk_key *disk_key,
988 struct btrfs_fs_info *fs_info = root->fs_info;
989 struct extent_buffer *ret;
992 * If we are COWing a node/leaf from the extent, chunk, device or free
993 * space trees, make sure that we do not finish block group creation of
994 * pending block groups. We do this to avoid a deadlock.
995 * COWing can result in allocation of a new chunk, and flushing pending
996 * block groups (btrfs_create_pending_block_groups()) can be triggered
997 * when finishing allocation of a new chunk. Creation of a pending block
998 * group modifies the extent, chunk, device and free space trees,
999 * therefore we could deadlock with ourselves since we are holding a
1000 * lock on an extent buffer that btrfs_create_pending_block_groups() may
1002 * For similar reasons, we also need to delay flushing pending block
1003 * groups when splitting a leaf or node, from one of those trees, since
1004 * we are holding a write lock on it and its parent or when inserting a
1005 * new root node for one of those trees.
1007 if (root == fs_info->extent_root ||
1008 root == fs_info->chunk_root ||
1009 root == fs_info->dev_root ||
1010 root == fs_info->free_space_root)
1011 trans->can_flush_pending_bgs = false;
1013 ret = btrfs_alloc_tree_block(trans, root, parent_start,
1014 root->root_key.objectid, disk_key, level,
1016 trans->can_flush_pending_bgs = true;
1022 * does the dirty work in cow of a single block. The parent block (if
1023 * supplied) is updated to point to the new cow copy. The new buffer is marked
1024 * dirty and returned locked. If you modify the block it needs to be marked
1027 * search_start -- an allocation hint for the new block
1029 * empty_size -- a hint that you plan on doing more cow. This is the size in
1030 * bytes the allocator should try to find free next to the block it returns.
1031 * This is just a hint and may be ignored by the allocator.
1033 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1034 struct btrfs_root *root,
1035 struct extent_buffer *buf,
1036 struct extent_buffer *parent, int parent_slot,
1037 struct extent_buffer **cow_ret,
1038 u64 search_start, u64 empty_size)
1040 struct btrfs_fs_info *fs_info = root->fs_info;
1041 struct btrfs_disk_key disk_key;
1042 struct extent_buffer *cow;
1045 int unlock_orig = 0;
1046 u64 parent_start = 0;
1048 if (*cow_ret == buf)
1051 btrfs_assert_tree_locked(buf);
1053 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1054 trans->transid != fs_info->running_transaction->transid);
1055 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1056 trans->transid != root->last_trans);
1058 level = btrfs_header_level(buf);
1061 btrfs_item_key(buf, &disk_key, 0);
1063 btrfs_node_key(buf, &disk_key, 0);
1065 if ((root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) && parent)
1066 parent_start = parent->start;
1068 cow = alloc_tree_block_no_bg_flush(trans, root, parent_start, &disk_key,
1069 level, search_start, empty_size);
1071 return PTR_ERR(cow);
1073 /* cow is set to blocking by btrfs_init_new_buffer */
1075 copy_extent_buffer_full(cow, buf);
1076 btrfs_set_header_bytenr(cow, cow->start);
1077 btrfs_set_header_generation(cow, trans->transid);
1078 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1079 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1080 BTRFS_HEADER_FLAG_RELOC);
1081 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1082 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1084 btrfs_set_header_owner(cow, root->root_key.objectid);
1086 write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
1088 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1090 btrfs_abort_transaction(trans, ret);
1094 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
1095 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1097 btrfs_abort_transaction(trans, ret);
1102 if (buf == root->node) {
1103 WARN_ON(parent && parent != buf);
1104 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1105 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1106 parent_start = buf->start;
1108 extent_buffer_get(cow);
1109 ret = tree_mod_log_insert_root(root->node, cow, 1);
1111 rcu_assign_pointer(root->node, cow);
1113 btrfs_free_tree_block(trans, root, buf, parent_start,
1115 free_extent_buffer(buf);
1116 add_root_to_dirty_list(root);
1118 WARN_ON(trans->transid != btrfs_header_generation(parent));
1119 tree_mod_log_insert_key(parent, parent_slot,
1120 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1121 btrfs_set_node_blockptr(parent, parent_slot,
1123 btrfs_set_node_ptr_generation(parent, parent_slot,
1125 btrfs_mark_buffer_dirty(parent);
1127 ret = tree_mod_log_free_eb(buf);
1129 btrfs_abort_transaction(trans, ret);
1133 btrfs_free_tree_block(trans, root, buf, parent_start,
1137 btrfs_tree_unlock(buf);
1138 free_extent_buffer_stale(buf);
1139 btrfs_mark_buffer_dirty(cow);
1145 * returns the logical address of the oldest predecessor of the given root.
1146 * entries older than time_seq are ignored.
1148 static struct tree_mod_elem *__tree_mod_log_oldest_root(
1149 struct extent_buffer *eb_root, u64 time_seq)
1151 struct tree_mod_elem *tm;
1152 struct tree_mod_elem *found = NULL;
1153 u64 root_logical = eb_root->start;
1160 * the very last operation that's logged for a root is the
1161 * replacement operation (if it is replaced at all). this has
1162 * the logical address of the *new* root, making it the very
1163 * first operation that's logged for this root.
1166 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
1171 * if there are no tree operation for the oldest root, we simply
1172 * return it. this should only happen if that (old) root is at
1179 * if there's an operation that's not a root replacement, we
1180 * found the oldest version of our root. normally, we'll find a
1181 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1183 if (tm->op != MOD_LOG_ROOT_REPLACE)
1187 root_logical = tm->old_root.logical;
1191 /* if there's no old root to return, return what we found instead */
1199 * tm is a pointer to the first operation to rewind within eb. then, all
1200 * previous operations will be rewound (until we reach something older than
1204 __tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1205 u64 time_seq, struct tree_mod_elem *first_tm)
1208 struct rb_node *next;
1209 struct tree_mod_elem *tm = first_tm;
1210 unsigned long o_dst;
1211 unsigned long o_src;
1212 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1214 n = btrfs_header_nritems(eb);
1215 read_lock(&fs_info->tree_mod_log_lock);
1216 while (tm && tm->seq >= time_seq) {
1218 * all the operations are recorded with the operator used for
1219 * the modification. as we're going backwards, we do the
1220 * opposite of each operation here.
1223 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1224 BUG_ON(tm->slot < n);
1226 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1227 case MOD_LOG_KEY_REMOVE:
1228 btrfs_set_node_key(eb, &tm->key, tm->slot);
1229 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1230 btrfs_set_node_ptr_generation(eb, tm->slot,
1234 case MOD_LOG_KEY_REPLACE:
1235 BUG_ON(tm->slot >= n);
1236 btrfs_set_node_key(eb, &tm->key, tm->slot);
1237 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1238 btrfs_set_node_ptr_generation(eb, tm->slot,
1241 case MOD_LOG_KEY_ADD:
1242 /* if a move operation is needed it's in the log */
1245 case MOD_LOG_MOVE_KEYS:
1246 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1247 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1248 memmove_extent_buffer(eb, o_dst, o_src,
1249 tm->move.nr_items * p_size);
1251 case MOD_LOG_ROOT_REPLACE:
1253 * this operation is special. for roots, this must be
1254 * handled explicitly before rewinding.
1255 * for non-roots, this operation may exist if the node
1256 * was a root: root A -> child B; then A gets empty and
1257 * B is promoted to the new root. in the mod log, we'll
1258 * have a root-replace operation for B, a tree block
1259 * that is no root. we simply ignore that operation.
1263 next = rb_next(&tm->node);
1266 tm = rb_entry(next, struct tree_mod_elem, node);
1267 if (tm->logical != first_tm->logical)
1270 read_unlock(&fs_info->tree_mod_log_lock);
1271 btrfs_set_header_nritems(eb, n);
1275 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
1276 * is returned. If rewind operations happen, a fresh buffer is returned. The
1277 * returned buffer is always read-locked. If the returned buffer is not the
1278 * input buffer, the lock on the input buffer is released and the input buffer
1279 * is freed (its refcount is decremented).
1281 static struct extent_buffer *
1282 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1283 struct extent_buffer *eb, u64 time_seq)
1285 struct extent_buffer *eb_rewin;
1286 struct tree_mod_elem *tm;
1291 if (btrfs_header_level(eb) == 0)
1294 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1298 btrfs_set_path_blocking(path);
1299 btrfs_set_lock_blocking_read(eb);
1301 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1302 BUG_ON(tm->slot != 0);
1303 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
1305 btrfs_tree_read_unlock_blocking(eb);
1306 free_extent_buffer(eb);
1309 btrfs_set_header_bytenr(eb_rewin, eb->start);
1310 btrfs_set_header_backref_rev(eb_rewin,
1311 btrfs_header_backref_rev(eb));
1312 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1313 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1315 eb_rewin = btrfs_clone_extent_buffer(eb);
1317 btrfs_tree_read_unlock_blocking(eb);
1318 free_extent_buffer(eb);
1323 btrfs_tree_read_unlock_blocking(eb);
1324 free_extent_buffer(eb);
1326 btrfs_tree_read_lock(eb_rewin);
1327 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1328 WARN_ON(btrfs_header_nritems(eb_rewin) >
1329 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1335 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1336 * value. If there are no changes, the current root->root_node is returned. If
1337 * anything changed in between, there's a fresh buffer allocated on which the
1338 * rewind operations are done. In any case, the returned buffer is read locked.
1339 * Returns NULL on error (with no locks held).
1341 static inline struct extent_buffer *
1342 get_old_root(struct btrfs_root *root, u64 time_seq)
1344 struct btrfs_fs_info *fs_info = root->fs_info;
1345 struct tree_mod_elem *tm;
1346 struct extent_buffer *eb = NULL;
1347 struct extent_buffer *eb_root;
1348 struct extent_buffer *old;
1349 struct tree_mod_root *old_root = NULL;
1350 u64 old_generation = 0;
1354 eb_root = btrfs_read_lock_root_node(root);
1355 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1359 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1360 old_root = &tm->old_root;
1361 old_generation = tm->generation;
1362 logical = old_root->logical;
1363 level = old_root->level;
1365 logical = eb_root->start;
1366 level = btrfs_header_level(eb_root);
1369 tm = tree_mod_log_search(fs_info, logical, time_seq);
1370 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1371 btrfs_tree_read_unlock(eb_root);
1372 free_extent_buffer(eb_root);
1373 old = read_tree_block(fs_info, logical, 0, level, NULL);
1374 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1376 free_extent_buffer(old);
1378 "failed to read tree block %llu from get_old_root",
1381 eb = btrfs_clone_extent_buffer(old);
1382 free_extent_buffer(old);
1384 } else if (old_root) {
1385 btrfs_tree_read_unlock(eb_root);
1386 free_extent_buffer(eb_root);
1387 eb = alloc_dummy_extent_buffer(fs_info, logical);
1389 btrfs_set_lock_blocking_read(eb_root);
1390 eb = btrfs_clone_extent_buffer(eb_root);
1391 btrfs_tree_read_unlock_blocking(eb_root);
1392 free_extent_buffer(eb_root);
1397 btrfs_tree_read_lock(eb);
1399 btrfs_set_header_bytenr(eb, eb->start);
1400 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1401 btrfs_set_header_owner(eb, btrfs_header_owner(eb_root));
1402 btrfs_set_header_level(eb, old_root->level);
1403 btrfs_set_header_generation(eb, old_generation);
1406 __tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1408 WARN_ON(btrfs_header_level(eb) != 0);
1409 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1414 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1416 struct tree_mod_elem *tm;
1418 struct extent_buffer *eb_root = btrfs_root_node(root);
1420 tm = __tree_mod_log_oldest_root(eb_root, time_seq);
1421 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1422 level = tm->old_root.level;
1424 level = btrfs_header_level(eb_root);
1426 free_extent_buffer(eb_root);
1431 static inline int should_cow_block(struct btrfs_trans_handle *trans,
1432 struct btrfs_root *root,
1433 struct extent_buffer *buf)
1435 if (btrfs_is_testing(root->fs_info))
1438 /* Ensure we can see the FORCE_COW bit */
1439 smp_mb__before_atomic();
1442 * We do not need to cow a block if
1443 * 1) this block is not created or changed in this transaction;
1444 * 2) this block does not belong to TREE_RELOC tree;
1445 * 3) the root is not forced COW.
1447 * What is forced COW:
1448 * when we create snapshot during committing the transaction,
1449 * after we've finished copying src root, we must COW the shared
1450 * block to ensure the metadata consistency.
1452 if (btrfs_header_generation(buf) == trans->transid &&
1453 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1454 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1455 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1456 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1462 * cows a single block, see __btrfs_cow_block for the real work.
1463 * This version of it has extra checks so that a block isn't COWed more than
1464 * once per transaction, as long as it hasn't been written yet
1466 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1467 struct btrfs_root *root, struct extent_buffer *buf,
1468 struct extent_buffer *parent, int parent_slot,
1469 struct extent_buffer **cow_ret)
1471 struct btrfs_fs_info *fs_info = root->fs_info;
1475 if (test_bit(BTRFS_ROOT_DELETING, &root->state))
1477 "COW'ing blocks on a fs root that's being dropped");
1479 if (trans->transaction != fs_info->running_transaction)
1480 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1482 fs_info->running_transaction->transid);
1484 if (trans->transid != fs_info->generation)
1485 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1486 trans->transid, fs_info->generation);
1488 if (!should_cow_block(trans, root, buf)) {
1489 trans->dirty = true;
1494 search_start = buf->start & ~((u64)SZ_1G - 1);
1497 btrfs_set_lock_blocking_write(parent);
1498 btrfs_set_lock_blocking_write(buf);
1501 * Before CoWing this block for later modification, check if it's
1502 * the subtree root and do the delayed subtree trace if needed.
1504 * Also We don't care about the error, as it's handled internally.
1506 btrfs_qgroup_trace_subtree_after_cow(trans, root, buf);
1507 ret = __btrfs_cow_block(trans, root, buf, parent,
1508 parent_slot, cow_ret, search_start, 0);
1510 trace_btrfs_cow_block(root, buf, *cow_ret);
1516 * helper function for defrag to decide if two blocks pointed to by a
1517 * node are actually close by
1519 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1521 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1523 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1529 * compare two keys in a memcmp fashion
1531 static int comp_keys(const struct btrfs_disk_key *disk,
1532 const struct btrfs_key *k2)
1534 struct btrfs_key k1;
1536 btrfs_disk_key_to_cpu(&k1, disk);
1538 return btrfs_comp_cpu_keys(&k1, k2);
1542 * same as comp_keys only with two btrfs_key's
1544 int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2)
1546 if (k1->objectid > k2->objectid)
1548 if (k1->objectid < k2->objectid)
1550 if (k1->type > k2->type)
1552 if (k1->type < k2->type)
1554 if (k1->offset > k2->offset)
1556 if (k1->offset < k2->offset)
1562 * this is used by the defrag code to go through all the
1563 * leaves pointed to by a node and reallocate them so that
1564 * disk order is close to key order
1566 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1567 struct btrfs_root *root, struct extent_buffer *parent,
1568 int start_slot, u64 *last_ret,
1569 struct btrfs_key *progress)
1571 struct btrfs_fs_info *fs_info = root->fs_info;
1572 struct extent_buffer *cur;
1575 u64 search_start = *last_ret;
1585 int progress_passed = 0;
1586 struct btrfs_disk_key disk_key;
1588 parent_level = btrfs_header_level(parent);
1590 WARN_ON(trans->transaction != fs_info->running_transaction);
1591 WARN_ON(trans->transid != fs_info->generation);
1593 parent_nritems = btrfs_header_nritems(parent);
1594 blocksize = fs_info->nodesize;
1595 end_slot = parent_nritems - 1;
1597 if (parent_nritems <= 1)
1600 btrfs_set_lock_blocking_write(parent);
1602 for (i = start_slot; i <= end_slot; i++) {
1603 struct btrfs_key first_key;
1606 btrfs_node_key(parent, &disk_key, i);
1607 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1610 progress_passed = 1;
1611 blocknr = btrfs_node_blockptr(parent, i);
1612 gen = btrfs_node_ptr_generation(parent, i);
1613 btrfs_node_key_to_cpu(parent, &first_key, i);
1614 if (last_block == 0)
1615 last_block = blocknr;
1618 other = btrfs_node_blockptr(parent, i - 1);
1619 close = close_blocks(blocknr, other, blocksize);
1621 if (!close && i < end_slot) {
1622 other = btrfs_node_blockptr(parent, i + 1);
1623 close = close_blocks(blocknr, other, blocksize);
1626 last_block = blocknr;
1630 cur = find_extent_buffer(fs_info, blocknr);
1632 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1635 if (!cur || !uptodate) {
1637 cur = read_tree_block(fs_info, blocknr, gen,
1641 return PTR_ERR(cur);
1642 } else if (!extent_buffer_uptodate(cur)) {
1643 free_extent_buffer(cur);
1646 } else if (!uptodate) {
1647 err = btrfs_read_buffer(cur, gen,
1648 parent_level - 1,&first_key);
1650 free_extent_buffer(cur);
1655 if (search_start == 0)
1656 search_start = last_block;
1658 btrfs_tree_lock(cur);
1659 btrfs_set_lock_blocking_write(cur);
1660 err = __btrfs_cow_block(trans, root, cur, parent, i,
1663 (end_slot - i) * blocksize));
1665 btrfs_tree_unlock(cur);
1666 free_extent_buffer(cur);
1669 search_start = cur->start;
1670 last_block = cur->start;
1671 *last_ret = search_start;
1672 btrfs_tree_unlock(cur);
1673 free_extent_buffer(cur);
1679 * search for key in the extent_buffer. The items start at offset p,
1680 * and they are item_size apart. There are 'max' items in p.
1682 * the slot in the array is returned via slot, and it points to
1683 * the place where you would insert key if it is not found in
1686 * slot may point to max if the key is bigger than all of the keys
1688 static noinline int generic_bin_search(struct extent_buffer *eb,
1689 unsigned long p, int item_size,
1690 const struct btrfs_key *key,
1697 struct btrfs_disk_key *tmp = NULL;
1698 struct btrfs_disk_key unaligned;
1699 unsigned long offset;
1701 unsigned long map_start = 0;
1702 unsigned long map_len = 0;
1706 btrfs_err(eb->fs_info,
1707 "%s: low (%d) > high (%d) eb %llu owner %llu level %d",
1708 __func__, low, high, eb->start,
1709 btrfs_header_owner(eb), btrfs_header_level(eb));
1713 while (low < high) {
1714 mid = (low + high) / 2;
1715 offset = p + mid * item_size;
1717 if (!kaddr || offset < map_start ||
1718 (offset + sizeof(struct btrfs_disk_key)) >
1719 map_start + map_len) {
1721 err = map_private_extent_buffer(eb, offset,
1722 sizeof(struct btrfs_disk_key),
1723 &kaddr, &map_start, &map_len);
1726 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1728 } else if (err == 1) {
1729 read_extent_buffer(eb, &unaligned,
1730 offset, sizeof(unaligned));
1737 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1740 ret = comp_keys(tmp, key);
1756 * simple bin_search frontend that does the right thing for
1759 int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key,
1760 int level, int *slot)
1763 return generic_bin_search(eb,
1764 offsetof(struct btrfs_leaf, items),
1765 sizeof(struct btrfs_item),
1766 key, btrfs_header_nritems(eb),
1769 return generic_bin_search(eb,
1770 offsetof(struct btrfs_node, ptrs),
1771 sizeof(struct btrfs_key_ptr),
1772 key, btrfs_header_nritems(eb),
1776 static void root_add_used(struct btrfs_root *root, u32 size)
1778 spin_lock(&root->accounting_lock);
1779 btrfs_set_root_used(&root->root_item,
1780 btrfs_root_used(&root->root_item) + size);
1781 spin_unlock(&root->accounting_lock);
1784 static void root_sub_used(struct btrfs_root *root, u32 size)
1786 spin_lock(&root->accounting_lock);
1787 btrfs_set_root_used(&root->root_item,
1788 btrfs_root_used(&root->root_item) - size);
1789 spin_unlock(&root->accounting_lock);
1792 /* given a node and slot number, this reads the blocks it points to. The
1793 * extent buffer is returned with a reference taken (but unlocked).
1795 static noinline struct extent_buffer *read_node_slot(
1796 struct extent_buffer *parent, int slot)
1798 int level = btrfs_header_level(parent);
1799 struct extent_buffer *eb;
1800 struct btrfs_key first_key;
1802 if (slot < 0 || slot >= btrfs_header_nritems(parent))
1803 return ERR_PTR(-ENOENT);
1807 btrfs_node_key_to_cpu(parent, &first_key, slot);
1808 eb = read_tree_block(parent->fs_info, btrfs_node_blockptr(parent, slot),
1809 btrfs_node_ptr_generation(parent, slot),
1810 level - 1, &first_key);
1811 if (!IS_ERR(eb) && !extent_buffer_uptodate(eb)) {
1812 free_extent_buffer(eb);
1820 * node level balancing, used to make sure nodes are in proper order for
1821 * item deletion. We balance from the top down, so we have to make sure
1822 * that a deletion won't leave an node completely empty later on.
1824 static noinline int balance_level(struct btrfs_trans_handle *trans,
1825 struct btrfs_root *root,
1826 struct btrfs_path *path, int level)
1828 struct btrfs_fs_info *fs_info = root->fs_info;
1829 struct extent_buffer *right = NULL;
1830 struct extent_buffer *mid;
1831 struct extent_buffer *left = NULL;
1832 struct extent_buffer *parent = NULL;
1836 int orig_slot = path->slots[level];
1841 mid = path->nodes[level];
1843 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1844 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1845 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1847 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1849 if (level < BTRFS_MAX_LEVEL - 1) {
1850 parent = path->nodes[level + 1];
1851 pslot = path->slots[level + 1];
1855 * deal with the case where there is only one pointer in the root
1856 * by promoting the node below to a root
1859 struct extent_buffer *child;
1861 if (btrfs_header_nritems(mid) != 1)
1864 /* promote the child to a root */
1865 child = read_node_slot(mid, 0);
1866 if (IS_ERR(child)) {
1867 ret = PTR_ERR(child);
1868 btrfs_handle_fs_error(fs_info, ret, NULL);
1872 btrfs_tree_lock(child);
1873 btrfs_set_lock_blocking_write(child);
1874 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1876 btrfs_tree_unlock(child);
1877 free_extent_buffer(child);
1881 ret = tree_mod_log_insert_root(root->node, child, 1);
1883 rcu_assign_pointer(root->node, child);
1885 add_root_to_dirty_list(root);
1886 btrfs_tree_unlock(child);
1888 path->locks[level] = 0;
1889 path->nodes[level] = NULL;
1890 btrfs_clean_tree_block(mid);
1891 btrfs_tree_unlock(mid);
1892 /* once for the path */
1893 free_extent_buffer(mid);
1895 root_sub_used(root, mid->len);
1896 btrfs_free_tree_block(trans, root, mid, 0, 1);
1897 /* once for the root ptr */
1898 free_extent_buffer_stale(mid);
1901 if (btrfs_header_nritems(mid) >
1902 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 4)
1905 left = read_node_slot(parent, pslot - 1);
1910 btrfs_tree_lock(left);
1911 btrfs_set_lock_blocking_write(left);
1912 wret = btrfs_cow_block(trans, root, left,
1913 parent, pslot - 1, &left);
1920 right = read_node_slot(parent, pslot + 1);
1925 btrfs_tree_lock(right);
1926 btrfs_set_lock_blocking_write(right);
1927 wret = btrfs_cow_block(trans, root, right,
1928 parent, pslot + 1, &right);
1935 /* first, try to make some room in the middle buffer */
1937 orig_slot += btrfs_header_nritems(left);
1938 wret = push_node_left(trans, fs_info, left, mid, 1);
1944 * then try to empty the right most buffer into the middle
1947 wret = push_node_left(trans, fs_info, mid, right, 1);
1948 if (wret < 0 && wret != -ENOSPC)
1950 if (btrfs_header_nritems(right) == 0) {
1951 btrfs_clean_tree_block(right);
1952 btrfs_tree_unlock(right);
1953 del_ptr(root, path, level + 1, pslot + 1);
1954 root_sub_used(root, right->len);
1955 btrfs_free_tree_block(trans, root, right, 0, 1);
1956 free_extent_buffer_stale(right);
1959 struct btrfs_disk_key right_key;
1960 btrfs_node_key(right, &right_key, 0);
1961 ret = tree_mod_log_insert_key(parent, pslot + 1,
1962 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1964 btrfs_set_node_key(parent, &right_key, pslot + 1);
1965 btrfs_mark_buffer_dirty(parent);
1968 if (btrfs_header_nritems(mid) == 1) {
1970 * we're not allowed to leave a node with one item in the
1971 * tree during a delete. A deletion from lower in the tree
1972 * could try to delete the only pointer in this node.
1973 * So, pull some keys from the left.
1974 * There has to be a left pointer at this point because
1975 * otherwise we would have pulled some pointers from the
1980 btrfs_handle_fs_error(fs_info, ret, NULL);
1983 wret = balance_node_right(trans, fs_info, mid, left);
1989 wret = push_node_left(trans, fs_info, left, mid, 1);
1995 if (btrfs_header_nritems(mid) == 0) {
1996 btrfs_clean_tree_block(mid);
1997 btrfs_tree_unlock(mid);
1998 del_ptr(root, path, level + 1, pslot);
1999 root_sub_used(root, mid->len);
2000 btrfs_free_tree_block(trans, root, mid, 0, 1);
2001 free_extent_buffer_stale(mid);
2004 /* update the parent key to reflect our changes */
2005 struct btrfs_disk_key mid_key;
2006 btrfs_node_key(mid, &mid_key, 0);
2007 ret = tree_mod_log_insert_key(parent, pslot,
2008 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2010 btrfs_set_node_key(parent, &mid_key, pslot);
2011 btrfs_mark_buffer_dirty(parent);
2014 /* update the path */
2016 if (btrfs_header_nritems(left) > orig_slot) {
2017 extent_buffer_get(left);
2018 /* left was locked after cow */
2019 path->nodes[level] = left;
2020 path->slots[level + 1] -= 1;
2021 path->slots[level] = orig_slot;
2023 btrfs_tree_unlock(mid);
2024 free_extent_buffer(mid);
2027 orig_slot -= btrfs_header_nritems(left);
2028 path->slots[level] = orig_slot;
2031 /* double check we haven't messed things up */
2033 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2037 btrfs_tree_unlock(right);
2038 free_extent_buffer(right);
2041 if (path->nodes[level] != left)
2042 btrfs_tree_unlock(left);
2043 free_extent_buffer(left);
2048 /* Node balancing for insertion. Here we only split or push nodes around
2049 * when they are completely full. This is also done top down, so we
2050 * have to be pessimistic.
2052 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2053 struct btrfs_root *root,
2054 struct btrfs_path *path, int level)
2056 struct btrfs_fs_info *fs_info = root->fs_info;
2057 struct extent_buffer *right = NULL;
2058 struct extent_buffer *mid;
2059 struct extent_buffer *left = NULL;
2060 struct extent_buffer *parent = NULL;
2064 int orig_slot = path->slots[level];
2069 mid = path->nodes[level];
2070 WARN_ON(btrfs_header_generation(mid) != trans->transid);
2072 if (level < BTRFS_MAX_LEVEL - 1) {
2073 parent = path->nodes[level + 1];
2074 pslot = path->slots[level + 1];
2080 left = read_node_slot(parent, pslot - 1);
2084 /* first, try to make some room in the middle buffer */
2088 btrfs_tree_lock(left);
2089 btrfs_set_lock_blocking_write(left);
2091 left_nr = btrfs_header_nritems(left);
2092 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2095 ret = btrfs_cow_block(trans, root, left, parent,
2100 wret = push_node_left(trans, fs_info,
2107 struct btrfs_disk_key disk_key;
2108 orig_slot += left_nr;
2109 btrfs_node_key(mid, &disk_key, 0);
2110 ret = tree_mod_log_insert_key(parent, pslot,
2111 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2113 btrfs_set_node_key(parent, &disk_key, pslot);
2114 btrfs_mark_buffer_dirty(parent);
2115 if (btrfs_header_nritems(left) > orig_slot) {
2116 path->nodes[level] = left;
2117 path->slots[level + 1] -= 1;
2118 path->slots[level] = orig_slot;
2119 btrfs_tree_unlock(mid);
2120 free_extent_buffer(mid);
2123 btrfs_header_nritems(left);
2124 path->slots[level] = orig_slot;
2125 btrfs_tree_unlock(left);
2126 free_extent_buffer(left);
2130 btrfs_tree_unlock(left);
2131 free_extent_buffer(left);
2133 right = read_node_slot(parent, pslot + 1);
2138 * then try to empty the right most buffer into the middle
2143 btrfs_tree_lock(right);
2144 btrfs_set_lock_blocking_write(right);
2146 right_nr = btrfs_header_nritems(right);
2147 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 1) {
2150 ret = btrfs_cow_block(trans, root, right,
2156 wret = balance_node_right(trans, fs_info,
2163 struct btrfs_disk_key disk_key;
2165 btrfs_node_key(right, &disk_key, 0);
2166 ret = tree_mod_log_insert_key(parent, pslot + 1,
2167 MOD_LOG_KEY_REPLACE, GFP_NOFS);
2169 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2170 btrfs_mark_buffer_dirty(parent);
2172 if (btrfs_header_nritems(mid) <= orig_slot) {
2173 path->nodes[level] = right;
2174 path->slots[level + 1] += 1;
2175 path->slots[level] = orig_slot -
2176 btrfs_header_nritems(mid);
2177 btrfs_tree_unlock(mid);
2178 free_extent_buffer(mid);
2180 btrfs_tree_unlock(right);
2181 free_extent_buffer(right);
2185 btrfs_tree_unlock(right);
2186 free_extent_buffer(right);
2192 * readahead one full node of leaves, finding things that are close
2193 * to the block in 'slot', and triggering ra on them.
2195 static void reada_for_search(struct btrfs_fs_info *fs_info,
2196 struct btrfs_path *path,
2197 int level, int slot, u64 objectid)
2199 struct extent_buffer *node;
2200 struct btrfs_disk_key disk_key;
2205 struct extent_buffer *eb;
2213 if (!path->nodes[level])
2216 node = path->nodes[level];
2218 search = btrfs_node_blockptr(node, slot);
2219 blocksize = fs_info->nodesize;
2220 eb = find_extent_buffer(fs_info, search);
2222 free_extent_buffer(eb);
2228 nritems = btrfs_header_nritems(node);
2232 if (path->reada == READA_BACK) {
2236 } else if (path->reada == READA_FORWARD) {
2241 if (path->reada == READA_BACK && objectid) {
2242 btrfs_node_key(node, &disk_key, nr);
2243 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2246 search = btrfs_node_blockptr(node, nr);
2247 if ((search <= target && target - search <= 65536) ||
2248 (search > target && search - target <= 65536)) {
2249 readahead_tree_block(fs_info, search);
2253 if ((nread > 65536 || nscan > 32))
2258 static noinline void reada_for_balance(struct btrfs_fs_info *fs_info,
2259 struct btrfs_path *path, int level)
2263 struct extent_buffer *parent;
2264 struct extent_buffer *eb;
2269 parent = path->nodes[level + 1];
2273 nritems = btrfs_header_nritems(parent);
2274 slot = path->slots[level + 1];
2277 block1 = btrfs_node_blockptr(parent, slot - 1);
2278 gen = btrfs_node_ptr_generation(parent, slot - 1);
2279 eb = find_extent_buffer(fs_info, block1);
2281 * if we get -eagain from btrfs_buffer_uptodate, we
2282 * don't want to return eagain here. That will loop
2285 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2287 free_extent_buffer(eb);
2289 if (slot + 1 < nritems) {
2290 block2 = btrfs_node_blockptr(parent, slot + 1);
2291 gen = btrfs_node_ptr_generation(parent, slot + 1);
2292 eb = find_extent_buffer(fs_info, block2);
2293 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2295 free_extent_buffer(eb);
2299 readahead_tree_block(fs_info, block1);
2301 readahead_tree_block(fs_info, block2);
2306 * when we walk down the tree, it is usually safe to unlock the higher layers
2307 * in the tree. The exceptions are when our path goes through slot 0, because
2308 * operations on the tree might require changing key pointers higher up in the
2311 * callers might also have set path->keep_locks, which tells this code to keep
2312 * the lock if the path points to the last slot in the block. This is part of
2313 * walking through the tree, and selecting the next slot in the higher block.
2315 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2316 * if lowest_unlock is 1, level 0 won't be unlocked
2318 static noinline void unlock_up(struct btrfs_path *path, int level,
2319 int lowest_unlock, int min_write_lock_level,
2320 int *write_lock_level)
2323 int skip_level = level;
2325 struct extent_buffer *t;
2327 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2328 if (!path->nodes[i])
2330 if (!path->locks[i])
2332 if (!no_skips && path->slots[i] == 0) {
2336 if (!no_skips && path->keep_locks) {
2339 nritems = btrfs_header_nritems(t);
2340 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2345 if (skip_level < i && i >= lowest_unlock)
2349 if (i >= lowest_unlock && i > skip_level) {
2350 btrfs_tree_unlock_rw(t, path->locks[i]);
2352 if (write_lock_level &&
2353 i > min_write_lock_level &&
2354 i <= *write_lock_level) {
2355 *write_lock_level = i - 1;
2362 * This releases any locks held in the path starting at level and
2363 * going all the way up to the root.
2365 * btrfs_search_slot will keep the lock held on higher nodes in a few
2366 * corner cases, such as COW of the block at slot zero in the node. This
2367 * ignores those rules, and it should only be called when there are no
2368 * more updates to be done higher up in the tree.
2370 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2374 if (path->keep_locks)
2377 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2378 if (!path->nodes[i])
2380 if (!path->locks[i])
2382 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2388 * helper function for btrfs_search_slot. The goal is to find a block
2389 * in cache without setting the path to blocking. If we find the block
2390 * we return zero and the path is unchanged.
2392 * If we can't find the block, we set the path blocking and do some
2393 * reada. -EAGAIN is returned and the search must be repeated.
2396 read_block_for_search(struct btrfs_root *root, struct btrfs_path *p,
2397 struct extent_buffer **eb_ret, int level, int slot,
2398 const struct btrfs_key *key)
2400 struct btrfs_fs_info *fs_info = root->fs_info;
2403 struct extent_buffer *b = *eb_ret;
2404 struct extent_buffer *tmp;
2405 struct btrfs_key first_key;
2409 blocknr = btrfs_node_blockptr(b, slot);
2410 gen = btrfs_node_ptr_generation(b, slot);
2411 parent_level = btrfs_header_level(b);
2412 btrfs_node_key_to_cpu(b, &first_key, slot);
2414 tmp = find_extent_buffer(fs_info, blocknr);
2416 /* first we do an atomic uptodate check */
2417 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2419 * Do extra check for first_key, eb can be stale due to
2420 * being cached, read from scrub, or have multiple
2421 * parents (shared tree blocks).
2423 if (btrfs_verify_level_key(fs_info, tmp,
2424 parent_level - 1, &first_key, gen)) {
2425 free_extent_buffer(tmp);
2432 /* the pages were up to date, but we failed
2433 * the generation number check. Do a full
2434 * read for the generation number that is correct.
2435 * We must do this without dropping locks so
2436 * we can trust our generation number
2438 btrfs_set_path_blocking(p);
2440 /* now we're allowed to do a blocking uptodate check */
2441 ret = btrfs_read_buffer(tmp, gen, parent_level - 1, &first_key);
2446 free_extent_buffer(tmp);
2447 btrfs_release_path(p);
2452 * reduce lock contention at high levels
2453 * of the btree by dropping locks before
2454 * we read. Don't release the lock on the current
2455 * level because we need to walk this node to figure
2456 * out which blocks to read.
2458 btrfs_unlock_up_safe(p, level + 1);
2459 btrfs_set_path_blocking(p);
2461 if (p->reada != READA_NONE)
2462 reada_for_search(fs_info, p, level, slot, key->objectid);
2465 tmp = read_tree_block(fs_info, blocknr, gen, parent_level - 1,
2469 * If the read above didn't mark this buffer up to date,
2470 * it will never end up being up to date. Set ret to EIO now
2471 * and give up so that our caller doesn't loop forever
2474 if (!extent_buffer_uptodate(tmp))
2476 free_extent_buffer(tmp);
2481 btrfs_release_path(p);
2486 * helper function for btrfs_search_slot. This does all of the checks
2487 * for node-level blocks and does any balancing required based on
2490 * If no extra work was required, zero is returned. If we had to
2491 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2495 setup_nodes_for_search(struct btrfs_trans_handle *trans,
2496 struct btrfs_root *root, struct btrfs_path *p,
2497 struct extent_buffer *b, int level, int ins_len,
2498 int *write_lock_level)
2500 struct btrfs_fs_info *fs_info = root->fs_info;
2503 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2504 BTRFS_NODEPTRS_PER_BLOCK(fs_info) - 3) {
2507 if (*write_lock_level < level + 1) {
2508 *write_lock_level = level + 1;
2509 btrfs_release_path(p);
2513 btrfs_set_path_blocking(p);
2514 reada_for_balance(fs_info, p, level);
2515 sret = split_node(trans, root, p, level);
2522 b = p->nodes[level];
2523 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2524 BTRFS_NODEPTRS_PER_BLOCK(fs_info) / 2) {
2527 if (*write_lock_level < level + 1) {
2528 *write_lock_level = level + 1;
2529 btrfs_release_path(p);
2533 btrfs_set_path_blocking(p);
2534 reada_for_balance(fs_info, p, level);
2535 sret = balance_level(trans, root, p, level);
2541 b = p->nodes[level];
2543 btrfs_release_path(p);
2546 BUG_ON(btrfs_header_nritems(b) == 1);
2556 static int key_search(struct extent_buffer *b, const struct btrfs_key *key,
2557 int level, int *prev_cmp, int *slot)
2559 if (*prev_cmp != 0) {
2560 *prev_cmp = btrfs_bin_search(b, key, level, slot);
2569 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2570 u64 iobjectid, u64 ioff, u8 key_type,
2571 struct btrfs_key *found_key)
2574 struct btrfs_key key;
2575 struct extent_buffer *eb;
2580 key.type = key_type;
2581 key.objectid = iobjectid;
2584 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2588 eb = path->nodes[0];
2589 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2590 ret = btrfs_next_leaf(fs_root, path);
2593 eb = path->nodes[0];
2596 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2597 if (found_key->type != key.type ||
2598 found_key->objectid != key.objectid)
2604 static struct extent_buffer *btrfs_search_slot_get_root(struct btrfs_root *root,
2605 struct btrfs_path *p,
2606 int write_lock_level)
2608 struct btrfs_fs_info *fs_info = root->fs_info;
2609 struct extent_buffer *b;
2613 /* We try very hard to do read locks on the root */
2614 root_lock = BTRFS_READ_LOCK;
2616 if (p->search_commit_root) {
2618 * The commit roots are read only so we always do read locks,
2619 * and we always must hold the commit_root_sem when doing
2620 * searches on them, the only exception is send where we don't
2621 * want to block transaction commits for a long time, so
2622 * we need to clone the commit root in order to avoid races
2623 * with transaction commits that create a snapshot of one of
2624 * the roots used by a send operation.
2626 if (p->need_commit_sem) {
2627 down_read(&fs_info->commit_root_sem);
2628 b = btrfs_clone_extent_buffer(root->commit_root);
2629 up_read(&fs_info->commit_root_sem);
2631 return ERR_PTR(-ENOMEM);
2634 b = root->commit_root;
2635 extent_buffer_get(b);
2637 level = btrfs_header_level(b);
2639 * Ensure that all callers have set skip_locking when
2640 * p->search_commit_root = 1.
2642 ASSERT(p->skip_locking == 1);
2647 if (p->skip_locking) {
2648 b = btrfs_root_node(root);
2649 level = btrfs_header_level(b);
2654 * If the level is set to maximum, we can skip trying to get the read
2657 if (write_lock_level < BTRFS_MAX_LEVEL) {
2659 * We don't know the level of the root node until we actually
2660 * have it read locked
2662 b = btrfs_read_lock_root_node(root);
2663 level = btrfs_header_level(b);
2664 if (level > write_lock_level)
2667 /* Whoops, must trade for write lock */
2668 btrfs_tree_read_unlock(b);
2669 free_extent_buffer(b);
2672 b = btrfs_lock_root_node(root);
2673 root_lock = BTRFS_WRITE_LOCK;
2675 /* The level might have changed, check again */
2676 level = btrfs_header_level(b);
2679 p->nodes[level] = b;
2680 if (!p->skip_locking)
2681 p->locks[level] = root_lock;
2683 * Callers are responsible for dropping b's references.
2690 * btrfs_search_slot - look for a key in a tree and perform necessary
2691 * modifications to preserve tree invariants.
2693 * @trans: Handle of transaction, used when modifying the tree
2694 * @p: Holds all btree nodes along the search path
2695 * @root: The root node of the tree
2696 * @key: The key we are looking for
2697 * @ins_len: Indicates purpose of search, for inserts it is 1, for
2698 * deletions it's -1. 0 for plain searches
2699 * @cow: boolean should CoW operations be performed. Must always be 1
2700 * when modifying the tree.
2702 * If @ins_len > 0, nodes and leaves will be split as we walk down the tree.
2703 * If @ins_len < 0, nodes will be merged as we walk down the tree (if possible)
2705 * If @key is found, 0 is returned and you can find the item in the leaf level
2706 * of the path (level 0)
2708 * If @key isn't found, 1 is returned and the leaf level of the path (level 0)
2709 * points to the slot where it should be inserted
2711 * If an error is encountered while searching the tree a negative error number
2714 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2715 const struct btrfs_key *key, struct btrfs_path *p,
2716 int ins_len, int cow)
2718 struct extent_buffer *b;
2723 int lowest_unlock = 1;
2724 /* everything at write_lock_level or lower must be write locked */
2725 int write_lock_level = 0;
2726 u8 lowest_level = 0;
2727 int min_write_lock_level;
2730 lowest_level = p->lowest_level;
2731 WARN_ON(lowest_level && ins_len > 0);
2732 WARN_ON(p->nodes[0] != NULL);
2733 BUG_ON(!cow && ins_len);
2738 /* when we are removing items, we might have to go up to level
2739 * two as we update tree pointers Make sure we keep write
2740 * for those levels as well
2742 write_lock_level = 2;
2743 } else if (ins_len > 0) {
2745 * for inserting items, make sure we have a write lock on
2746 * level 1 so we can update keys
2748 write_lock_level = 1;
2752 write_lock_level = -1;
2754 if (cow && (p->keep_locks || p->lowest_level))
2755 write_lock_level = BTRFS_MAX_LEVEL;
2757 min_write_lock_level = write_lock_level;
2761 b = btrfs_search_slot_get_root(root, p, write_lock_level);
2768 level = btrfs_header_level(b);
2771 * setup the path here so we can release it under lock
2772 * contention with the cow code
2775 bool last_level = (level == (BTRFS_MAX_LEVEL - 1));
2778 * if we don't really need to cow this block
2779 * then we don't want to set the path blocking,
2780 * so we test it here
2782 if (!should_cow_block(trans, root, b)) {
2783 trans->dirty = true;
2788 * must have write locks on this node and the
2791 if (level > write_lock_level ||
2792 (level + 1 > write_lock_level &&
2793 level + 1 < BTRFS_MAX_LEVEL &&
2794 p->nodes[level + 1])) {
2795 write_lock_level = level + 1;
2796 btrfs_release_path(p);
2800 btrfs_set_path_blocking(p);
2802 err = btrfs_cow_block(trans, root, b, NULL, 0,
2805 err = btrfs_cow_block(trans, root, b,
2806 p->nodes[level + 1],
2807 p->slots[level + 1], &b);
2814 p->nodes[level] = b;
2816 * Leave path with blocking locks to avoid massive
2817 * lock context switch, this is made on purpose.
2821 * we have a lock on b and as long as we aren't changing
2822 * the tree, there is no way to for the items in b to change.
2823 * It is safe to drop the lock on our parent before we
2824 * go through the expensive btree search on b.
2826 * If we're inserting or deleting (ins_len != 0), then we might
2827 * be changing slot zero, which may require changing the parent.
2828 * So, we can't drop the lock until after we know which slot
2829 * we're operating on.
2831 if (!ins_len && !p->keep_locks) {
2834 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2835 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2840 ret = key_search(b, key, level, &prev_cmp, &slot);
2846 if (ret && slot > 0) {
2850 p->slots[level] = slot;
2851 err = setup_nodes_for_search(trans, root, p, b, level,
2852 ins_len, &write_lock_level);
2859 b = p->nodes[level];
2860 slot = p->slots[level];
2863 * slot 0 is special, if we change the key
2864 * we have to update the parent pointer
2865 * which means we must have a write lock
2868 if (slot == 0 && ins_len &&
2869 write_lock_level < level + 1) {
2870 write_lock_level = level + 1;
2871 btrfs_release_path(p);
2875 unlock_up(p, level, lowest_unlock,
2876 min_write_lock_level, &write_lock_level);
2878 if (level == lowest_level) {
2884 err = read_block_for_search(root, p, &b, level,
2893 if (!p->skip_locking) {
2894 level = btrfs_header_level(b);
2895 if (level <= write_lock_level) {
2896 err = btrfs_try_tree_write_lock(b);
2898 btrfs_set_path_blocking(p);
2901 p->locks[level] = BTRFS_WRITE_LOCK;
2903 err = btrfs_tree_read_lock_atomic(b);
2905 btrfs_set_path_blocking(p);
2906 btrfs_tree_read_lock(b);
2908 p->locks[level] = BTRFS_READ_LOCK;
2910 p->nodes[level] = b;
2913 p->slots[level] = slot;
2915 btrfs_leaf_free_space(b) < ins_len) {
2916 if (write_lock_level < 1) {
2917 write_lock_level = 1;
2918 btrfs_release_path(p);
2922 btrfs_set_path_blocking(p);
2923 err = split_leaf(trans, root, key,
2924 p, ins_len, ret == 0);
2932 if (!p->search_for_split)
2933 unlock_up(p, level, lowest_unlock,
2934 min_write_lock_level, NULL);
2941 * we don't really know what they plan on doing with the path
2942 * from here on, so for now just mark it as blocking
2944 if (!p->leave_spinning)
2945 btrfs_set_path_blocking(p);
2946 if (ret < 0 && !p->skip_release_on_error)
2947 btrfs_release_path(p);
2952 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2953 * current state of the tree together with the operations recorded in the tree
2954 * modification log to search for the key in a previous version of this tree, as
2955 * denoted by the time_seq parameter.
2957 * Naturally, there is no support for insert, delete or cow operations.
2959 * The resulting path and return value will be set up as if we called
2960 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2962 int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key,
2963 struct btrfs_path *p, u64 time_seq)
2965 struct btrfs_fs_info *fs_info = root->fs_info;
2966 struct extent_buffer *b;
2971 int lowest_unlock = 1;
2972 u8 lowest_level = 0;
2975 lowest_level = p->lowest_level;
2976 WARN_ON(p->nodes[0] != NULL);
2978 if (p->search_commit_root) {
2980 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2984 b = get_old_root(root, time_seq);
2989 level = btrfs_header_level(b);
2990 p->locks[level] = BTRFS_READ_LOCK;
2993 level = btrfs_header_level(b);
2994 p->nodes[level] = b;
2997 * we have a lock on b and as long as we aren't changing
2998 * the tree, there is no way to for the items in b to change.
2999 * It is safe to drop the lock on our parent before we
3000 * go through the expensive btree search on b.
3002 btrfs_unlock_up_safe(p, level + 1);
3005 * Since we can unwind ebs we want to do a real search every
3009 ret = key_search(b, key, level, &prev_cmp, &slot);
3015 if (ret && slot > 0) {
3019 p->slots[level] = slot;
3020 unlock_up(p, level, lowest_unlock, 0, NULL);
3022 if (level == lowest_level) {
3028 err = read_block_for_search(root, p, &b, level,
3037 level = btrfs_header_level(b);
3038 err = btrfs_tree_read_lock_atomic(b);
3040 btrfs_set_path_blocking(p);
3041 btrfs_tree_read_lock(b);
3043 b = tree_mod_log_rewind(fs_info, p, b, time_seq);
3048 p->locks[level] = BTRFS_READ_LOCK;
3049 p->nodes[level] = b;
3051 p->slots[level] = slot;
3052 unlock_up(p, level, lowest_unlock, 0, NULL);
3058 if (!p->leave_spinning)
3059 btrfs_set_path_blocking(p);
3061 btrfs_release_path(p);
3067 * helper to use instead of search slot if no exact match is needed but
3068 * instead the next or previous item should be returned.
3069 * When find_higher is true, the next higher item is returned, the next lower
3071 * When return_any and find_higher are both true, and no higher item is found,
3072 * return the next lower instead.
3073 * When return_any is true and find_higher is false, and no lower item is found,
3074 * return the next higher instead.
3075 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3078 int btrfs_search_slot_for_read(struct btrfs_root *root,
3079 const struct btrfs_key *key,
3080 struct btrfs_path *p, int find_higher,
3084 struct extent_buffer *leaf;
3087 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3091 * a return value of 1 means the path is at the position where the
3092 * item should be inserted. Normally this is the next bigger item,
3093 * but in case the previous item is the last in a leaf, path points
3094 * to the first free slot in the previous leaf, i.e. at an invalid
3100 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3101 ret = btrfs_next_leaf(root, p);
3107 * no higher item found, return the next
3112 btrfs_release_path(p);
3116 if (p->slots[0] == 0) {
3117 ret = btrfs_prev_leaf(root, p);
3122 if (p->slots[0] == btrfs_header_nritems(leaf))
3129 * no lower item found, return the next
3134 btrfs_release_path(p);
3144 * adjust the pointers going up the tree, starting at level
3145 * making sure the right key of each node is points to 'key'.
3146 * This is used after shifting pointers to the left, so it stops
3147 * fixing up pointers when a given leaf/node is not in slot 0 of the
3151 static void fixup_low_keys(struct btrfs_path *path,
3152 struct btrfs_disk_key *key, int level)
3155 struct extent_buffer *t;
3158 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3159 int tslot = path->slots[i];
3161 if (!path->nodes[i])
3164 ret = tree_mod_log_insert_key(t, tslot, MOD_LOG_KEY_REPLACE,
3167 btrfs_set_node_key(t, key, tslot);
3168 btrfs_mark_buffer_dirty(path->nodes[i]);
3177 * This function isn't completely safe. It's the caller's responsibility
3178 * that the new key won't break the order
3180 void btrfs_set_item_key_safe(struct btrfs_fs_info *fs_info,
3181 struct btrfs_path *path,
3182 const struct btrfs_key *new_key)
3184 struct btrfs_disk_key disk_key;
3185 struct extent_buffer *eb;
3188 eb = path->nodes[0];
3189 slot = path->slots[0];
3191 btrfs_item_key(eb, &disk_key, slot - 1);
3192 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
3194 if (slot < btrfs_header_nritems(eb) - 1) {
3195 btrfs_item_key(eb, &disk_key, slot + 1);
3196 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
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 btrfs_fs_info *fs_info,
3215 struct extent_buffer *dst,
3216 struct extent_buffer *src, int empty)
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 btrfs_fs_info *fs_info,
3289 struct extent_buffer *dst,
3290 struct extent_buffer *src)
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 extent_buffer_get(c);
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_fs_info *fs_info, 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(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, fs_info, 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);
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_fs_info *fs_info,
3597 struct btrfs_path *path,
3598 int data_size, int empty,
3599 struct extent_buffer *right,
3600 int free_space, u32 left_nritems,
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;
3617 btrfs_init_map_token(&token);
3622 nr = max_t(u32, 1, min_slot);
3624 if (path->slots[0] >= left_nritems)
3625 push_space += data_size;
3627 slot = path->slots[1];
3628 i = left_nritems - 1;
3630 item = btrfs_item_nr(i);
3632 if (!empty && push_items > 0) {
3633 if (path->slots[0] > i)
3635 if (path->slots[0] == i) {
3636 int space = btrfs_leaf_free_space(left);
3638 if (space + push_space * 2 > free_space)
3643 if (path->slots[0] == i)
3644 push_space += data_size;
3646 this_item_size = btrfs_item_size(left, item);
3647 if (this_item_size + sizeof(*item) + push_space > free_space)
3651 push_space += this_item_size + sizeof(*item);
3657 if (push_items == 0)
3660 WARN_ON(!empty && push_items == left_nritems);
3662 /* push left to right */
3663 right_nritems = btrfs_header_nritems(right);
3665 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3666 push_space -= leaf_data_end(left);
3668 /* make room in the right data area */
3669 data_end = leaf_data_end(right);
3670 memmove_extent_buffer(right,
3671 BTRFS_LEAF_DATA_OFFSET + data_end - push_space,
3672 BTRFS_LEAF_DATA_OFFSET + data_end,
3673 BTRFS_LEAF_DATA_SIZE(fs_info) - data_end);
3675 /* copy from the left data area */
3676 copy_extent_buffer(right, left, BTRFS_LEAF_DATA_OFFSET +
3677 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3678 BTRFS_LEAF_DATA_OFFSET + leaf_data_end(left),
3681 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3682 btrfs_item_nr_offset(0),
3683 right_nritems * sizeof(struct btrfs_item));
3685 /* copy the items from left to right */
3686 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3687 btrfs_item_nr_offset(left_nritems - push_items),
3688 push_items * sizeof(struct btrfs_item));
3690 /* update the item pointers */
3691 right_nritems += push_items;
3692 btrfs_set_header_nritems(right, right_nritems);
3693 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3694 for (i = 0; i < right_nritems; i++) {
3695 item = btrfs_item_nr(i);
3696 push_space -= btrfs_token_item_size(right, item, &token);
3697 btrfs_set_token_item_offset(right, item, push_space, &token);
3700 left_nritems -= push_items;
3701 btrfs_set_header_nritems(left, left_nritems);
3704 btrfs_mark_buffer_dirty(left);
3706 btrfs_clean_tree_block(left);
3708 btrfs_mark_buffer_dirty(right);
3710 btrfs_item_key(right, &disk_key, 0);
3711 btrfs_set_node_key(upper, &disk_key, slot + 1);
3712 btrfs_mark_buffer_dirty(upper);
3714 /* then fixup the leaf pointer in the path */
3715 if (path->slots[0] >= left_nritems) {
3716 path->slots[0] -= left_nritems;
3717 if (btrfs_header_nritems(path->nodes[0]) == 0)
3718 btrfs_clean_tree_block(path->nodes[0]);
3719 btrfs_tree_unlock(path->nodes[0]);
3720 free_extent_buffer(path->nodes[0]);
3721 path->nodes[0] = right;
3722 path->slots[1] += 1;
3724 btrfs_tree_unlock(right);
3725 free_extent_buffer(right);
3730 btrfs_tree_unlock(right);
3731 free_extent_buffer(right);
3736 * push some data in the path leaf to the right, trying to free up at
3737 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3739 * returns 1 if the push failed because the other node didn't have enough
3740 * room, 0 if everything worked out and < 0 if there were major errors.
3742 * this will push starting from min_slot to the end of the leaf. It won't
3743 * push any slot lower than min_slot
3745 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3746 *root, struct btrfs_path *path,
3747 int min_data_size, int data_size,
3748 int empty, u32 min_slot)
3750 struct btrfs_fs_info *fs_info = root->fs_info;
3751 struct extent_buffer *left = path->nodes[0];
3752 struct extent_buffer *right;
3753 struct extent_buffer *upper;
3759 if (!path->nodes[1])
3762 slot = path->slots[1];
3763 upper = path->nodes[1];
3764 if (slot >= btrfs_header_nritems(upper) - 1)
3767 btrfs_assert_tree_locked(path->nodes[1]);
3769 right = read_node_slot(upper, slot + 1);
3771 * slot + 1 is not valid or we fail to read the right node,
3772 * no big deal, just return.
3777 btrfs_tree_lock(right);
3778 btrfs_set_lock_blocking_write(right);
3780 free_space = btrfs_leaf_free_space(right);
3781 if (free_space < data_size)
3784 /* cow and double check */
3785 ret = btrfs_cow_block(trans, root, right, upper,
3790 free_space = btrfs_leaf_free_space(right);
3791 if (free_space < data_size)
3794 left_nritems = btrfs_header_nritems(left);
3795 if (left_nritems == 0)
3798 if (path->slots[0] == left_nritems && !empty) {
3799 /* Key greater than all keys in the leaf, right neighbor has
3800 * enough room for it and we're not emptying our leaf to delete
3801 * it, therefore use right neighbor to insert the new item and
3802 * no need to touch/dirty our left leaf. */
3803 btrfs_tree_unlock(left);
3804 free_extent_buffer(left);
3805 path->nodes[0] = right;
3811 return __push_leaf_right(fs_info, path, min_data_size, empty,
3812 right, free_space, left_nritems, min_slot);
3814 btrfs_tree_unlock(right);
3815 free_extent_buffer(right);
3820 * push some data in the path leaf to the left, trying to free up at
3821 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3823 * max_slot can put a limit on how far into the leaf we'll push items. The
3824 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3827 static noinline int __push_leaf_left(struct btrfs_fs_info *fs_info,
3828 struct btrfs_path *path, int data_size,
3829 int empty, struct extent_buffer *left,
3830 int free_space, u32 right_nritems,
3833 struct btrfs_disk_key disk_key;
3834 struct extent_buffer *right = path->nodes[0];
3838 struct btrfs_item *item;
3839 u32 old_left_nritems;
3843 u32 old_left_item_size;
3844 struct btrfs_map_token token;
3846 btrfs_init_map_token(&token);
3849 nr = min(right_nritems, max_slot);
3851 nr = min(right_nritems - 1, max_slot);
3853 for (i = 0; i < nr; i++) {
3854 item = btrfs_item_nr(i);
3856 if (!empty && push_items > 0) {
3857 if (path->slots[0] < i)
3859 if (path->slots[0] == i) {
3860 int space = btrfs_leaf_free_space(right);
3862 if (space + push_space * 2 > free_space)
3867 if (path->slots[0] == i)
3868 push_space += data_size;
3870 this_item_size = btrfs_item_size(right, item);
3871 if (this_item_size + sizeof(*item) + push_space > free_space)
3875 push_space += this_item_size + sizeof(*item);
3878 if (push_items == 0) {
3882 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3884 /* push data from right to left */
3885 copy_extent_buffer(left, right,
3886 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3887 btrfs_item_nr_offset(0),
3888 push_items * sizeof(struct btrfs_item));
3890 push_space = BTRFS_LEAF_DATA_SIZE(fs_info) -
3891 btrfs_item_offset_nr(right, push_items - 1);
3893 copy_extent_buffer(left, right, BTRFS_LEAF_DATA_OFFSET +
3894 leaf_data_end(left) - push_space,
3895 BTRFS_LEAF_DATA_OFFSET +
3896 btrfs_item_offset_nr(right, push_items - 1),
3898 old_left_nritems = btrfs_header_nritems(left);
3899 BUG_ON(old_left_nritems <= 0);
3901 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3902 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3905 item = btrfs_item_nr(i);
3907 ioff = btrfs_token_item_offset(left, item, &token);
3908 btrfs_set_token_item_offset(left, item,
3909 ioff - (BTRFS_LEAF_DATA_SIZE(fs_info) - old_left_item_size),
3912 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3914 /* fixup right node */
3915 if (push_items > right_nritems)
3916 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3919 if (push_items < right_nritems) {
3920 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3921 leaf_data_end(right);
3922 memmove_extent_buffer(right, BTRFS_LEAF_DATA_OFFSET +
3923 BTRFS_LEAF_DATA_SIZE(fs_info) - push_space,
3924 BTRFS_LEAF_DATA_OFFSET +
3925 leaf_data_end(right), push_space);
3927 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3928 btrfs_item_nr_offset(push_items),
3929 (btrfs_header_nritems(right) - push_items) *
3930 sizeof(struct btrfs_item));
3932 right_nritems -= push_items;
3933 btrfs_set_header_nritems(right, right_nritems);
3934 push_space = BTRFS_LEAF_DATA_SIZE(fs_info);
3935 for (i = 0; i < right_nritems; i++) {
3936 item = btrfs_item_nr(i);
3938 push_space = push_space - btrfs_token_item_size(right,
3940 btrfs_set_token_item_offset(right, item, push_space, &token);
3943 btrfs_mark_buffer_dirty(left);
3945 btrfs_mark_buffer_dirty(right);
3947 btrfs_clean_tree_block(right);
3949 btrfs_item_key(right, &disk_key, 0);
3950 fixup_low_keys(path, &disk_key, 1);
3952 /* then fixup the leaf pointer in the path */
3953 if (path->slots[0] < push_items) {
3954 path->slots[0] += old_left_nritems;
3955 btrfs_tree_unlock(path->nodes[0]);
3956 free_extent_buffer(path->nodes[0]);
3957 path->nodes[0] = left;
3958 path->slots[1] -= 1;
3960 btrfs_tree_unlock(left);
3961 free_extent_buffer(left);
3962 path->slots[0] -= push_items;
3964 BUG_ON(path->slots[0] < 0);
3967 btrfs_tree_unlock(left);
3968 free_extent_buffer(left);
3973 * push some data in the path leaf to the left, trying to free up at
3974 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3976 * max_slot can put a limit on how far into the leaf we'll push items. The
3977 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3980 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3981 *root, struct btrfs_path *path, int min_data_size,
3982 int data_size, int empty, u32 max_slot)
3984 struct btrfs_fs_info *fs_info = root->fs_info;
3985 struct extent_buffer *right = path->nodes[0];
3986 struct extent_buffer *left;
3992 slot = path->slots[1];
3995 if (!path->nodes[1])
3998 right_nritems = btrfs_header_nritems(right);
3999 if (right_nritems == 0)
4002 btrfs_assert_tree_locked(path->nodes[1]);
4004 left = read_node_slot(path->nodes[1], slot - 1);
4006 * slot - 1 is not valid or we fail to read the left node,
4007 * no big deal, just return.
4012 btrfs_tree_lock(left);
4013 btrfs_set_lock_blocking_write(left);
4015 free_space = btrfs_leaf_free_space(left);
4016 if (free_space < data_size) {
4021 /* cow and double check */
4022 ret = btrfs_cow_block(trans, root, left,
4023 path->nodes[1], slot - 1, &left);
4025 /* we hit -ENOSPC, but it isn't fatal here */
4031 free_space = btrfs_leaf_free_space(left);
4032 if (free_space < data_size) {
4037 return __push_leaf_left(fs_info, path, min_data_size,
4038 empty, left, free_space, right_nritems,
4041 btrfs_tree_unlock(left);
4042 free_extent_buffer(left);
4047 * split the path's leaf in two, making sure there is at least data_size
4048 * available for the resulting leaf level of the path.
4050 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4051 struct btrfs_fs_info *fs_info,
4052 struct btrfs_path *path,
4053 struct extent_buffer *l,
4054 struct extent_buffer *right,
4055 int slot, int mid, int nritems)
4060 struct btrfs_disk_key disk_key;
4061 struct btrfs_map_token token;
4063 btrfs_init_map_token(&token);
4065 nritems = nritems - mid;
4066 btrfs_set_header_nritems(right, nritems);
4067 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(l);
4069 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4070 btrfs_item_nr_offset(mid),
4071 nritems * sizeof(struct btrfs_item));
4073 copy_extent_buffer(right, l,
4074 BTRFS_LEAF_DATA_OFFSET + BTRFS_LEAF_DATA_SIZE(fs_info) -
4075 data_copy_size, BTRFS_LEAF_DATA_OFFSET +
4076 leaf_data_end(l), data_copy_size);
4078 rt_data_off = BTRFS_LEAF_DATA_SIZE(fs_info) - btrfs_item_end_nr(l, mid);
4080 for (i = 0; i < nritems; i++) {
4081 struct btrfs_item *item = btrfs_item_nr(i);
4084 ioff = btrfs_token_item_offset(right, item, &token);
4085 btrfs_set_token_item_offset(right, item,
4086 ioff + rt_data_off, &token);
4089 btrfs_set_header_nritems(l, mid);
4090 btrfs_item_key(right, &disk_key, 0);
4091 insert_ptr(trans, fs_info, path, &disk_key, right->start,
4092 path->slots[1] + 1, 1);
4094 btrfs_mark_buffer_dirty(right);
4095 btrfs_mark_buffer_dirty(l);
4096 BUG_ON(path->slots[0] != slot);
4099 btrfs_tree_unlock(path->nodes[0]);
4100 free_extent_buffer(path->nodes[0]);
4101 path->nodes[0] = right;
4102 path->slots[0] -= mid;
4103 path->slots[1] += 1;
4105 btrfs_tree_unlock(right);
4106 free_extent_buffer(right);
4109 BUG_ON(path->slots[0] < 0);
4113 * double splits happen when we need to insert a big item in the middle
4114 * of a leaf. A double split can leave us with 3 mostly empty leaves:
4115 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4118 * We avoid this by trying to push the items on either side of our target
4119 * into the adjacent leaves. If all goes well we can avoid the double split
4122 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4123 struct btrfs_root *root,
4124 struct btrfs_path *path,
4131 int space_needed = data_size;
4133 slot = path->slots[0];
4134 if (slot < btrfs_header_nritems(path->nodes[0]))
4135 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4138 * try to push all the items after our slot into the
4141 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4148 nritems = btrfs_header_nritems(path->nodes[0]);
4150 * our goal is to get our slot at the start or end of a leaf. If
4151 * we've done so we're done
4153 if (path->slots[0] == 0 || path->slots[0] == nritems)
4156 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4159 /* try to push all the items before our slot into the next leaf */
4160 slot = path->slots[0];
4161 space_needed = data_size;
4163 space_needed -= btrfs_leaf_free_space(path->nodes[0]);
4164 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4177 * split the path's leaf in two, making sure there is at least data_size
4178 * available for the resulting leaf level of the path.
4180 * returns 0 if all went well and < 0 on failure.
4182 static noinline int split_leaf(struct btrfs_trans_handle *trans,
4183 struct btrfs_root *root,
4184 const struct btrfs_key *ins_key,
4185 struct btrfs_path *path, int data_size,
4188 struct btrfs_disk_key disk_key;
4189 struct extent_buffer *l;
4193 struct extent_buffer *right;
4194 struct btrfs_fs_info *fs_info = root->fs_info;
4198 int num_doubles = 0;
4199 int tried_avoid_double = 0;
4202 slot = path->slots[0];
4203 if (extend && data_size + btrfs_item_size_nr(l, slot) +
4204 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(fs_info))
4207 /* first try to make some room by pushing left and right */
4208 if (data_size && path->nodes[1]) {
4209 int space_needed = data_size;
4211 if (slot < btrfs_header_nritems(l))
4212 space_needed -= btrfs_leaf_free_space(l);
4214 wret = push_leaf_right(trans, root, path, space_needed,
4215 space_needed, 0, 0);
4219 space_needed = data_size;
4221 space_needed -= btrfs_leaf_free_space(l);
4222 wret = push_leaf_left(trans, root, path, space_needed,
4223 space_needed, 0, (u32)-1);
4229 /* did the pushes work? */
4230 if (btrfs_leaf_free_space(l) >= data_size)
4234 if (!path->nodes[1]) {
4235 ret = insert_new_root(trans, root, path, 1);
4242 slot = path->slots[0];
4243 nritems = btrfs_header_nritems(l);
4244 mid = (nritems + 1) / 2;
4248 leaf_space_used(l, mid, nritems - mid) + data_size >
4249 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4250 if (slot >= nritems) {
4254 if (mid != nritems &&
4255 leaf_space_used(l, mid, nritems - mid) +
4256 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4257 if (data_size && !tried_avoid_double)
4258 goto push_for_double;
4264 if (leaf_space_used(l, 0, mid) + data_size >
4265 BTRFS_LEAF_DATA_SIZE(fs_info)) {
4266 if (!extend && data_size && slot == 0) {
4268 } else if ((extend || !data_size) && slot == 0) {
4272 if (mid != nritems &&
4273 leaf_space_used(l, mid, nritems - mid) +
4274 data_size > BTRFS_LEAF_DATA_SIZE(fs_info)) {
4275 if (data_size && !tried_avoid_double)
4276 goto push_for_double;
4284 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4286 btrfs_item_key(l, &disk_key, mid);
4288 right = alloc_tree_block_no_bg_flush(trans, root, 0, &disk_key, 0,
4291 return PTR_ERR(right);
4293 root_add_used(root, fs_info->nodesize);
4297 btrfs_set_header_nritems(right, 0);
4298 insert_ptr(trans, fs_info, path, &disk_key,
4299 right->start, path->slots[1] + 1, 1);
4300 btrfs_tree_unlock(path->nodes[0]);
4301 free_extent_buffer(path->nodes[0]);
4302 path->nodes[0] = right;
4304 path->slots[1] += 1;
4306 btrfs_set_header_nritems(right, 0);
4307 insert_ptr(trans, fs_info, path, &disk_key,
4308 right->start, path->slots[1], 1);
4309 btrfs_tree_unlock(path->nodes[0]);
4310 free_extent_buffer(path->nodes[0]);
4311 path->nodes[0] = right;
4313 if (path->slots[1] == 0)
4314 fixup_low_keys(path, &disk_key, 1);
4317 * We create a new leaf 'right' for the required ins_len and
4318 * we'll do btrfs_mark_buffer_dirty() on this leaf after copying
4319 * the content of ins_len to 'right'.
4324 copy_for_split(trans, fs_info, path, l, right, slot, mid, nritems);
4327 BUG_ON(num_doubles != 0);
4335 push_for_double_split(trans, root, path, data_size);
4336 tried_avoid_double = 1;
4337 if (btrfs_leaf_free_space(path->nodes[0]) >= data_size)
4342 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4343 struct btrfs_root *root,
4344 struct btrfs_path *path, int ins_len)
4346 struct btrfs_key key;
4347 struct extent_buffer *leaf;
4348 struct btrfs_file_extent_item *fi;
4353 leaf = path->nodes[0];
4354 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4356 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4357 key.type != BTRFS_EXTENT_CSUM_KEY);
4359 if (btrfs_leaf_free_space(leaf) >= ins_len)
4362 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4363 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4364 fi = btrfs_item_ptr(leaf, path->slots[0],
4365 struct btrfs_file_extent_item);
4366 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4368 btrfs_release_path(path);
4370 path->keep_locks = 1;
4371 path->search_for_split = 1;
4372 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4373 path->search_for_split = 0;
4380 leaf = path->nodes[0];
4381 /* if our item isn't there, return now */
4382 if (item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4385 /* the leaf has changed, it now has room. return now */
4386 if (btrfs_leaf_free_space(path->nodes[0]) >= ins_len)
4389 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4390 fi = btrfs_item_ptr(leaf, path->slots[0],
4391 struct btrfs_file_extent_item);
4392 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4396 btrfs_set_path_blocking(path);
4397 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4401 path->keep_locks = 0;
4402 btrfs_unlock_up_safe(path, 1);
4405 path->keep_locks = 0;
4409 static noinline int split_item(struct btrfs_fs_info *fs_info,
4410 struct btrfs_path *path,
4411 const struct btrfs_key *new_key,
4412 unsigned long split_offset)
4414 struct extent_buffer *leaf;
4415 struct btrfs_item *item;
4416 struct btrfs_item *new_item;
4422 struct btrfs_disk_key disk_key;
4424 leaf = path->nodes[0];
4425 BUG_ON(btrfs_leaf_free_space(leaf) < sizeof(struct btrfs_item));
4427 btrfs_set_path_blocking(path);
4429 item = btrfs_item_nr(path->slots[0]);
4430 orig_offset = btrfs_item_offset(leaf, item);
4431 item_size = btrfs_item_size(leaf, item);
4433 buf = kmalloc(item_size, GFP_NOFS);
4437 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4438 path->slots[0]), item_size);
4440 slot = path->slots[0] + 1;
4441 nritems = btrfs_header_nritems(leaf);
4442 if (slot != nritems) {
4443 /* shift the items */
4444 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4445 btrfs_item_nr_offset(slot),
4446 (nritems - slot) * sizeof(struct btrfs_item));
4449 btrfs_cpu_key_to_disk(&disk_key, new_key);
4450 btrfs_set_item_key(leaf, &disk_key, slot);
4452 new_item = btrfs_item_nr(slot);
4454 btrfs_set_item_offset(leaf, new_item, orig_offset);
4455 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4457 btrfs_set_item_offset(leaf, item,
4458 orig_offset + item_size - split_offset);
4459 btrfs_set_item_size(leaf, item, split_offset);
4461 btrfs_set_header_nritems(leaf, nritems + 1);
4463 /* write the data for the start of the original item */
4464 write_extent_buffer(leaf, buf,
4465 btrfs_item_ptr_offset(leaf, path->slots[0]),
4468 /* write the data for the new item */
4469 write_extent_buffer(leaf, buf + split_offset,
4470 btrfs_item_ptr_offset(leaf, slot),
4471 item_size - split_offset);
4472 btrfs_mark_buffer_dirty(leaf);
4474 BUG_ON(btrfs_leaf_free_space(leaf) < 0);
4480 * This function splits a single item into two items,
4481 * giving 'new_key' to the new item and splitting the
4482 * old one at split_offset (from the start of the item).
4484 * The path may be released by this operation. After
4485 * the split, the path is pointing to the old item. The
4486 * new item is going to be in the same node as the old one.
4488 * Note, the item being split must be smaller enough to live alone on
4489 * a tree block with room for one extra struct btrfs_item
4491 * This allows us to split the item in place, keeping a lock on the
4492 * leaf the entire time.
4494 int btrfs_split_item(struct btrfs_trans_handle *trans,
4495 struct btrfs_root *root,
4496 struct btrfs_path *path,
4497 const struct btrfs_key *new_key,
4498 unsigned long split_offset)
4501 ret = setup_leaf_for_split(trans, root, path,
4502 sizeof(struct btrfs_item));
4506 ret = split_item(root->fs_info, path, new_key, split_offset);
4511 * This function duplicate a item, giving 'new_key' to the new item.
4512 * It guarantees both items live in the same tree leaf and the new item
4513 * is contiguous with the original item.
4515 * This allows us to split file extent in place, keeping a lock on the
4516 * leaf the entire time.
4518 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4519 struct btrfs_root *root,
4520 struct btrfs_path *path,
4521 const struct btrfs_key *new_key)
4523 struct extent_buffer *leaf;
4527 leaf = path->nodes[0];
4528 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4529 ret = setup_leaf_for_split(trans, root, path,
4530 item_size + sizeof(struct btrfs_item));
4535 setup_items_for_insert(root, path, new_key, &item_size,
4536 item_size, item_size +
4537 sizeof(struct btrfs_item), 1);
4538 leaf = path->nodes[0];
4539 memcpy_extent_buffer(leaf,
4540 btrfs_item_ptr_offset(leaf, path->slots[0]),
4541 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4547 * make the item pointed to by the path smaller. new_size indicates
4548 * how small to make it, and from_end tells us if we just chop bytes
4549 * off the end of the item or if we shift the item to chop bytes off
4552 void btrfs_truncate_item(struct btrfs_fs_info *fs_info,
4553 struct btrfs_path *path, u32 new_size, int from_end)
4556 struct extent_buffer *leaf;
4557 struct btrfs_item *item;
4559 unsigned int data_end;
4560 unsigned int old_data_start;
4561 unsigned int old_size;
4562 unsigned int size_diff;
4564 struct btrfs_map_token token;
4566 btrfs_init_map_token(&token);
4568 leaf = path->nodes[0];
4569 slot = path->slots[0];
4571 old_size = btrfs_item_size_nr(leaf, slot);
4572 if (old_size == new_size)
4575 nritems = btrfs_header_nritems(leaf);
4576 data_end = leaf_data_end(leaf);
4578 old_data_start = btrfs_item_offset_nr(leaf, slot);
4580 size_diff = old_size - new_size;
4583 BUG_ON(slot >= nritems);
4586 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4588 /* first correct the data pointers */
4589 for (i = slot; i < nritems; i++) {
4591 item = btrfs_item_nr(i);
4593 ioff = btrfs_token_item_offset(leaf, item, &token);
4594 btrfs_set_token_item_offset(leaf, item,
4595 ioff + size_diff, &token);
4598 /* shift the data */
4600 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4601 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4602 data_end, old_data_start + new_size - data_end);
4604 struct btrfs_disk_key disk_key;
4607 btrfs_item_key(leaf, &disk_key, slot);
4609 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4611 struct btrfs_file_extent_item *fi;
4613 fi = btrfs_item_ptr(leaf, slot,
4614 struct btrfs_file_extent_item);
4615 fi = (struct btrfs_file_extent_item *)(
4616 (unsigned long)fi - size_diff);
4618 if (btrfs_file_extent_type(leaf, fi) ==
4619 BTRFS_FILE_EXTENT_INLINE) {
4620 ptr = btrfs_item_ptr_offset(leaf, slot);
4621 memmove_extent_buffer(leaf, ptr,
4623 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4627 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4628 data_end + size_diff, BTRFS_LEAF_DATA_OFFSET +
4629 data_end, old_data_start - data_end);
4631 offset = btrfs_disk_key_offset(&disk_key);
4632 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4633 btrfs_set_item_key(leaf, &disk_key, slot);
4635 fixup_low_keys(path, &disk_key, 1);
4638 item = btrfs_item_nr(slot);
4639 btrfs_set_item_size(leaf, item, new_size);
4640 btrfs_mark_buffer_dirty(leaf);
4642 if (btrfs_leaf_free_space(leaf) < 0) {
4643 btrfs_print_leaf(leaf);
4649 * make the item pointed to by the path bigger, data_size is the added size.
4651 void btrfs_extend_item(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
4655 struct extent_buffer *leaf;
4656 struct btrfs_item *item;
4658 unsigned int data_end;
4659 unsigned int old_data;
4660 unsigned int old_size;
4662 struct btrfs_map_token token;
4664 btrfs_init_map_token(&token);
4666 leaf = path->nodes[0];
4668 nritems = btrfs_header_nritems(leaf);
4669 data_end = leaf_data_end(leaf);
4671 if (btrfs_leaf_free_space(leaf) < data_size) {
4672 btrfs_print_leaf(leaf);
4675 slot = path->slots[0];
4676 old_data = btrfs_item_end_nr(leaf, slot);
4679 if (slot >= nritems) {
4680 btrfs_print_leaf(leaf);
4681 btrfs_crit(fs_info, "slot %d too large, nritems %d",
4687 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4689 /* first correct the data pointers */
4690 for (i = slot; i < nritems; i++) {
4692 item = btrfs_item_nr(i);
4694 ioff = btrfs_token_item_offset(leaf, item, &token);
4695 btrfs_set_token_item_offset(leaf, item,
4696 ioff - data_size, &token);
4699 /* shift the data */
4700 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4701 data_end - data_size, BTRFS_LEAF_DATA_OFFSET +
4702 data_end, old_data - data_end);
4704 data_end = old_data;
4705 old_size = btrfs_item_size_nr(leaf, slot);
4706 item = btrfs_item_nr(slot);
4707 btrfs_set_item_size(leaf, item, old_size + data_size);
4708 btrfs_mark_buffer_dirty(leaf);
4710 if (btrfs_leaf_free_space(leaf) < 0) {
4711 btrfs_print_leaf(leaf);
4717 * this is a helper for btrfs_insert_empty_items, the main goal here is
4718 * to save stack depth by doing the bulk of the work in a function
4719 * that doesn't call btrfs_search_slot
4721 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4722 const struct btrfs_key *cpu_key, u32 *data_size,
4723 u32 total_data, u32 total_size, int nr)
4725 struct btrfs_fs_info *fs_info = root->fs_info;
4726 struct btrfs_item *item;
4729 unsigned int data_end;
4730 struct btrfs_disk_key disk_key;
4731 struct extent_buffer *leaf;
4733 struct btrfs_map_token token;
4735 if (path->slots[0] == 0) {
4736 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4737 fixup_low_keys(path, &disk_key, 1);
4739 btrfs_unlock_up_safe(path, 1);
4741 btrfs_init_map_token(&token);
4743 leaf = path->nodes[0];
4744 slot = path->slots[0];
4746 nritems = btrfs_header_nritems(leaf);
4747 data_end = leaf_data_end(leaf);
4749 if (btrfs_leaf_free_space(leaf) < total_size) {
4750 btrfs_print_leaf(leaf);
4751 btrfs_crit(fs_info, "not enough freespace need %u have %d",
4752 total_size, btrfs_leaf_free_space(leaf));
4756 if (slot != nritems) {
4757 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4759 if (old_data < data_end) {
4760 btrfs_print_leaf(leaf);
4761 btrfs_crit(fs_info, "slot %d old_data %d data_end %d",
4762 slot, old_data, data_end);
4766 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4768 /* first correct the data pointers */
4769 for (i = slot; i < nritems; i++) {
4772 item = btrfs_item_nr(i);
4773 ioff = btrfs_token_item_offset(leaf, item, &token);
4774 btrfs_set_token_item_offset(leaf, item,
4775 ioff - total_data, &token);
4777 /* shift the items */
4778 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4779 btrfs_item_nr_offset(slot),
4780 (nritems - slot) * sizeof(struct btrfs_item));
4782 /* shift the data */
4783 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4784 data_end - total_data, BTRFS_LEAF_DATA_OFFSET +
4785 data_end, old_data - data_end);
4786 data_end = old_data;
4789 /* setup the item for the new data */
4790 for (i = 0; i < nr; i++) {
4791 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4792 btrfs_set_item_key(leaf, &disk_key, slot + i);
4793 item = btrfs_item_nr(slot + i);
4794 btrfs_set_token_item_offset(leaf, item,
4795 data_end - data_size[i], &token);
4796 data_end -= data_size[i];
4797 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4800 btrfs_set_header_nritems(leaf, nritems + nr);
4801 btrfs_mark_buffer_dirty(leaf);
4803 if (btrfs_leaf_free_space(leaf) < 0) {
4804 btrfs_print_leaf(leaf);
4810 * Given a key and some data, insert items into the tree.
4811 * This does all the path init required, making room in the tree if needed.
4813 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4814 struct btrfs_root *root,
4815 struct btrfs_path *path,
4816 const struct btrfs_key *cpu_key, u32 *data_size,
4825 for (i = 0; i < nr; i++)
4826 total_data += data_size[i];
4828 total_size = total_data + (nr * sizeof(struct btrfs_item));
4829 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4835 slot = path->slots[0];
4838 setup_items_for_insert(root, path, cpu_key, data_size,
4839 total_data, total_size, nr);
4844 * Given a key and some data, insert an item into the tree.
4845 * This does all the path init required, making room in the tree if needed.
4847 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4848 const struct btrfs_key *cpu_key, void *data,
4852 struct btrfs_path *path;
4853 struct extent_buffer *leaf;
4856 path = btrfs_alloc_path();
4859 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4861 leaf = path->nodes[0];
4862 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4863 write_extent_buffer(leaf, data, ptr, data_size);
4864 btrfs_mark_buffer_dirty(leaf);
4866 btrfs_free_path(path);
4871 * delete the pointer from a given node.
4873 * the tree should have been previously balanced so the deletion does not
4876 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4877 int level, int slot)
4879 struct extent_buffer *parent = path->nodes[level];
4883 nritems = btrfs_header_nritems(parent);
4884 if (slot != nritems - 1) {
4886 ret = tree_mod_log_insert_move(parent, slot, slot + 1,
4887 nritems - slot - 1);
4890 memmove_extent_buffer(parent,
4891 btrfs_node_key_ptr_offset(slot),
4892 btrfs_node_key_ptr_offset(slot + 1),
4893 sizeof(struct btrfs_key_ptr) *
4894 (nritems - slot - 1));
4896 ret = tree_mod_log_insert_key(parent, slot, MOD_LOG_KEY_REMOVE,
4902 btrfs_set_header_nritems(parent, nritems);
4903 if (nritems == 0 && parent == root->node) {
4904 BUG_ON(btrfs_header_level(root->node) != 1);
4905 /* just turn the root into a leaf and break */
4906 btrfs_set_header_level(root->node, 0);
4907 } else if (slot == 0) {
4908 struct btrfs_disk_key disk_key;
4910 btrfs_node_key(parent, &disk_key, 0);
4911 fixup_low_keys(path, &disk_key, level + 1);
4913 btrfs_mark_buffer_dirty(parent);
4917 * a helper function to delete the leaf pointed to by path->slots[1] and
4920 * This deletes the pointer in path->nodes[1] and frees the leaf
4921 * block extent. zero is returned if it all worked out, < 0 otherwise.
4923 * The path must have already been setup for deleting the leaf, including
4924 * all the proper balancing. path->nodes[1] must be locked.
4926 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4927 struct btrfs_root *root,
4928 struct btrfs_path *path,
4929 struct extent_buffer *leaf)
4931 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4932 del_ptr(root, path, 1, path->slots[1]);
4935 * btrfs_free_extent is expensive, we want to make sure we
4936 * aren't holding any locks when we call it
4938 btrfs_unlock_up_safe(path, 0);
4940 root_sub_used(root, leaf->len);
4942 extent_buffer_get(leaf);
4943 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4944 free_extent_buffer_stale(leaf);
4947 * delete the item at the leaf level in path. If that empties
4948 * the leaf, remove it from the tree
4950 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4951 struct btrfs_path *path, int slot, int nr)
4953 struct btrfs_fs_info *fs_info = root->fs_info;
4954 struct extent_buffer *leaf;
4955 struct btrfs_item *item;
4962 struct btrfs_map_token token;
4964 btrfs_init_map_token(&token);
4966 leaf = path->nodes[0];
4967 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4969 for (i = 0; i < nr; i++)
4970 dsize += btrfs_item_size_nr(leaf, slot + i);
4972 nritems = btrfs_header_nritems(leaf);
4974 if (slot + nr != nritems) {
4975 int data_end = leaf_data_end(leaf);
4977 memmove_extent_buffer(leaf, BTRFS_LEAF_DATA_OFFSET +
4979 BTRFS_LEAF_DATA_OFFSET + data_end,
4980 last_off - data_end);
4982 for (i = slot + nr; i < nritems; i++) {
4985 item = btrfs_item_nr(i);
4986 ioff = btrfs_token_item_offset(leaf, item, &token);
4987 btrfs_set_token_item_offset(leaf, item,
4988 ioff + dsize, &token);
4991 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4992 btrfs_item_nr_offset(slot + nr),
4993 sizeof(struct btrfs_item) *
4994 (nritems - slot - nr));
4996 btrfs_set_header_nritems(leaf, nritems - nr);
4999 /* delete the leaf if we've emptied it */
5001 if (leaf == root->node) {
5002 btrfs_set_header_level(leaf, 0);
5004 btrfs_set_path_blocking(path);
5005 btrfs_clean_tree_block(leaf);
5006 btrfs_del_leaf(trans, root, path, leaf);
5009 int used = leaf_space_used(leaf, 0, nritems);
5011 struct btrfs_disk_key disk_key;
5013 btrfs_item_key(leaf, &disk_key, 0);
5014 fixup_low_keys(path, &disk_key, 1);
5017 /* delete the leaf if it is mostly empty */
5018 if (used < BTRFS_LEAF_DATA_SIZE(fs_info) / 3) {
5019 /* push_leaf_left fixes the path.
5020 * make sure the path still points to our leaf
5021 * for possible call to del_ptr below
5023 slot = path->slots[1];
5024 extent_buffer_get(leaf);
5026 btrfs_set_path_blocking(path);
5027 wret = push_leaf_left(trans, root, path, 1, 1,
5029 if (wret < 0 && wret != -ENOSPC)
5032 if (path->nodes[0] == leaf &&
5033 btrfs_header_nritems(leaf)) {
5034 wret = push_leaf_right(trans, root, path, 1,
5036 if (wret < 0 && wret != -ENOSPC)
5040 if (btrfs_header_nritems(leaf) == 0) {
5041 path->slots[1] = slot;
5042 btrfs_del_leaf(trans, root, path, leaf);
5043 free_extent_buffer(leaf);
5046 /* if we're still in the path, make sure
5047 * we're dirty. Otherwise, one of the
5048 * push_leaf functions must have already
5049 * dirtied this buffer
5051 if (path->nodes[0] == leaf)
5052 btrfs_mark_buffer_dirty(leaf);
5053 free_extent_buffer(leaf);
5056 btrfs_mark_buffer_dirty(leaf);
5063 * search the tree again to find a leaf with lesser keys
5064 * returns 0 if it found something or 1 if there are no lesser leaves.
5065 * returns < 0 on io errors.
5067 * This may release the path, and so you may lose any locks held at the
5070 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5072 struct btrfs_key key;
5073 struct btrfs_disk_key found_key;
5076 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5078 if (key.offset > 0) {
5080 } else if (key.type > 0) {
5082 key.offset = (u64)-1;
5083 } else if (key.objectid > 0) {
5086 key.offset = (u64)-1;
5091 btrfs_release_path(path);
5092 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5095 btrfs_item_key(path->nodes[0], &found_key, 0);
5096 ret = comp_keys(&found_key, &key);
5098 * We might have had an item with the previous key in the tree right
5099 * before we released our path. And after we released our path, that
5100 * item might have been pushed to the first slot (0) of the leaf we
5101 * were holding due to a tree balance. Alternatively, an item with the
5102 * previous key can exist as the only element of a leaf (big fat item).
5103 * Therefore account for these 2 cases, so that our callers (like
5104 * btrfs_previous_item) don't miss an existing item with a key matching
5105 * the previous key we computed above.
5113 * A helper function to walk down the tree starting at min_key, and looking
5114 * for nodes or leaves that are have a minimum transaction id.
5115 * This is used by the btree defrag code, and tree logging
5117 * This does not cow, but it does stuff the starting key it finds back
5118 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5119 * key and get a writable path.
5121 * This honors path->lowest_level to prevent descent past a given level
5124 * min_trans indicates the oldest transaction that you are interested
5125 * in walking through. Any nodes or leaves older than min_trans are
5126 * skipped over (without reading them).
5128 * returns zero if something useful was found, < 0 on error and 1 if there
5129 * was nothing in the tree that matched the search criteria.
5131 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5132 struct btrfs_path *path,
5135 struct extent_buffer *cur;
5136 struct btrfs_key found_key;
5142 int keep_locks = path->keep_locks;
5144 path->keep_locks = 1;
5146 cur = btrfs_read_lock_root_node(root);
5147 level = btrfs_header_level(cur);
5148 WARN_ON(path->nodes[level]);
5149 path->nodes[level] = cur;
5150 path->locks[level] = BTRFS_READ_LOCK;
5152 if (btrfs_header_generation(cur) < min_trans) {
5157 nritems = btrfs_header_nritems(cur);
5158 level = btrfs_header_level(cur);
5159 sret = btrfs_bin_search(cur, min_key, level, &slot);
5165 /* at the lowest level, we're done, setup the path and exit */
5166 if (level == path->lowest_level) {
5167 if (slot >= nritems)
5170 path->slots[level] = slot;
5171 btrfs_item_key_to_cpu(cur, &found_key, slot);
5174 if (sret && slot > 0)
5177 * check this node pointer against the min_trans parameters.
5178 * If it is too old, old, skip to the next one.
5180 while (slot < nritems) {
5183 gen = btrfs_node_ptr_generation(cur, slot);
5184 if (gen < min_trans) {
5192 * we didn't find a candidate key in this node, walk forward
5193 * and find another one
5195 if (slot >= nritems) {
5196 path->slots[level] = slot;
5197 btrfs_set_path_blocking(path);
5198 sret = btrfs_find_next_key(root, path, min_key, level,
5201 btrfs_release_path(path);
5207 /* save our key for returning back */
5208 btrfs_node_key_to_cpu(cur, &found_key, slot);
5209 path->slots[level] = slot;
5210 if (level == path->lowest_level) {
5214 btrfs_set_path_blocking(path);
5215 cur = read_node_slot(cur, slot);
5221 btrfs_tree_read_lock(cur);
5223 path->locks[level - 1] = BTRFS_READ_LOCK;
5224 path->nodes[level - 1] = cur;
5225 unlock_up(path, level, 1, 0, NULL);
5228 path->keep_locks = keep_locks;
5230 btrfs_unlock_up_safe(path, path->lowest_level + 1);
5231 btrfs_set_path_blocking(path);
5232 memcpy(min_key, &found_key, sizeof(found_key));
5237 static int tree_move_down(struct btrfs_fs_info *fs_info,
5238 struct btrfs_path *path,
5241 struct extent_buffer *eb;
5243 BUG_ON(*level == 0);
5244 eb = read_node_slot(path->nodes[*level], path->slots[*level]);
5248 path->nodes[*level - 1] = eb;
5249 path->slots[*level - 1] = 0;
5254 static int tree_move_next_or_upnext(struct btrfs_path *path,
5255 int *level, int root_level)
5259 nritems = btrfs_header_nritems(path->nodes[*level]);
5261 path->slots[*level]++;
5263 while (path->slots[*level] >= nritems) {
5264 if (*level == root_level)
5268 path->slots[*level] = 0;
5269 free_extent_buffer(path->nodes[*level]);
5270 path->nodes[*level] = NULL;
5272 path->slots[*level]++;
5274 nritems = btrfs_header_nritems(path->nodes[*level]);
5281 * Returns 1 if it had to move up and next. 0 is returned if it moved only next
5284 static int tree_advance(struct btrfs_fs_info *fs_info,
5285 struct btrfs_path *path,
5286 int *level, int root_level,
5288 struct btrfs_key *key)
5292 if (*level == 0 || !allow_down) {
5293 ret = tree_move_next_or_upnext(path, level, root_level);
5295 ret = tree_move_down(fs_info, path, level);
5299 btrfs_item_key_to_cpu(path->nodes[*level], key,
5300 path->slots[*level]);
5302 btrfs_node_key_to_cpu(path->nodes[*level], key,
5303 path->slots[*level]);
5308 static int tree_compare_item(struct btrfs_path *left_path,
5309 struct btrfs_path *right_path,
5314 unsigned long off1, off2;
5316 len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
5317 len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
5321 off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
5322 off2 = btrfs_item_ptr_offset(right_path->nodes[0],
5323 right_path->slots[0]);
5325 read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
5327 cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
5334 #define ADVANCE_ONLY_NEXT -1
5337 * This function compares two trees and calls the provided callback for
5338 * every changed/new/deleted item it finds.
5339 * If shared tree blocks are encountered, whole subtrees are skipped, making
5340 * the compare pretty fast on snapshotted subvolumes.
5342 * This currently works on commit roots only. As commit roots are read only,
5343 * we don't do any locking. The commit roots are protected with transactions.
5344 * Transactions are ended and rejoined when a commit is tried in between.
5346 * This function checks for modifications done to the trees while comparing.
5347 * If it detects a change, it aborts immediately.
5349 int btrfs_compare_trees(struct btrfs_root *left_root,
5350 struct btrfs_root *right_root,
5351 btrfs_changed_cb_t changed_cb, void *ctx)
5353 struct btrfs_fs_info *fs_info = left_root->fs_info;
5356 struct btrfs_path *left_path = NULL;
5357 struct btrfs_path *right_path = NULL;
5358 struct btrfs_key left_key;
5359 struct btrfs_key right_key;
5360 char *tmp_buf = NULL;
5361 int left_root_level;
5362 int right_root_level;
5365 int left_end_reached;
5366 int right_end_reached;
5374 left_path = btrfs_alloc_path();
5379 right_path = btrfs_alloc_path();
5385 tmp_buf = kvmalloc(fs_info->nodesize, GFP_KERNEL);
5391 left_path->search_commit_root = 1;
5392 left_path->skip_locking = 1;
5393 right_path->search_commit_root = 1;
5394 right_path->skip_locking = 1;
5397 * Strategy: Go to the first items of both trees. Then do
5399 * If both trees are at level 0
5400 * Compare keys of current items
5401 * If left < right treat left item as new, advance left tree
5403 * If left > right treat right item as deleted, advance right tree
5405 * If left == right do deep compare of items, treat as changed if
5406 * needed, advance both trees and repeat
5407 * If both trees are at the same level but not at level 0
5408 * Compare keys of current nodes/leafs
5409 * If left < right advance left tree and repeat
5410 * If left > right advance right tree and repeat
5411 * If left == right compare blockptrs of the next nodes/leafs
5412 * If they match advance both trees but stay at the same level
5414 * If they don't match advance both trees while allowing to go
5416 * If tree levels are different
5417 * Advance the tree that needs it and repeat
5419 * Advancing a tree means:
5420 * If we are at level 0, try to go to the next slot. If that's not
5421 * possible, go one level up and repeat. Stop when we found a level
5422 * where we could go to the next slot. We may at this point be on a
5425 * If we are not at level 0 and not on shared tree blocks, go one
5428 * If we are not at level 0 and on shared tree blocks, go one slot to
5429 * the right if possible or go up and right.
5432 down_read(&fs_info->commit_root_sem);
5433 left_level = btrfs_header_level(left_root->commit_root);
5434 left_root_level = left_level;
5435 left_path->nodes[left_level] =
5436 btrfs_clone_extent_buffer(left_root->commit_root);
5437 if (!left_path->nodes[left_level]) {
5438 up_read(&fs_info->commit_root_sem);
5443 right_level = btrfs_header_level(right_root->commit_root);
5444 right_root_level = right_level;
5445 right_path->nodes[right_level] =
5446 btrfs_clone_extent_buffer(right_root->commit_root);
5447 if (!right_path->nodes[right_level]) {
5448 up_read(&fs_info->commit_root_sem);
5452 up_read(&fs_info->commit_root_sem);
5454 if (left_level == 0)
5455 btrfs_item_key_to_cpu(left_path->nodes[left_level],
5456 &left_key, left_path->slots[left_level]);
5458 btrfs_node_key_to_cpu(left_path->nodes[left_level],
5459 &left_key, left_path->slots[left_level]);
5460 if (right_level == 0)
5461 btrfs_item_key_to_cpu(right_path->nodes[right_level],
5462 &right_key, right_path->slots[right_level]);
5464 btrfs_node_key_to_cpu(right_path->nodes[right_level],
5465 &right_key, right_path->slots[right_level]);
5467 left_end_reached = right_end_reached = 0;
5468 advance_left = advance_right = 0;
5471 if (advance_left && !left_end_reached) {
5472 ret = tree_advance(fs_info, left_path, &left_level,
5474 advance_left != ADVANCE_ONLY_NEXT,
5477 left_end_reached = ADVANCE;
5482 if (advance_right && !right_end_reached) {
5483 ret = tree_advance(fs_info, right_path, &right_level,
5485 advance_right != ADVANCE_ONLY_NEXT,
5488 right_end_reached = ADVANCE;
5494 if (left_end_reached && right_end_reached) {
5497 } else if (left_end_reached) {
5498 if (right_level == 0) {
5499 ret = changed_cb(left_path, right_path,
5501 BTRFS_COMPARE_TREE_DELETED,
5506 advance_right = ADVANCE;
5508 } else if (right_end_reached) {
5509 if (left_level == 0) {
5510 ret = changed_cb(left_path, right_path,
5512 BTRFS_COMPARE_TREE_NEW,
5517 advance_left = ADVANCE;
5521 if (left_level == 0 && right_level == 0) {
5522 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5524 ret = changed_cb(left_path, right_path,
5526 BTRFS_COMPARE_TREE_NEW,
5530 advance_left = ADVANCE;
5531 } else if (cmp > 0) {
5532 ret = changed_cb(left_path, right_path,
5534 BTRFS_COMPARE_TREE_DELETED,
5538 advance_right = ADVANCE;
5540 enum btrfs_compare_tree_result result;
5542 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
5543 ret = tree_compare_item(left_path, right_path,
5546 result = BTRFS_COMPARE_TREE_CHANGED;
5548 result = BTRFS_COMPARE_TREE_SAME;
5549 ret = changed_cb(left_path, right_path,
5550 &left_key, result, ctx);
5553 advance_left = ADVANCE;
5554 advance_right = ADVANCE;
5556 } else if (left_level == right_level) {
5557 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5559 advance_left = ADVANCE;
5560 } else if (cmp > 0) {
5561 advance_right = ADVANCE;
5563 left_blockptr = btrfs_node_blockptr(
5564 left_path->nodes[left_level],
5565 left_path->slots[left_level]);
5566 right_blockptr = btrfs_node_blockptr(
5567 right_path->nodes[right_level],
5568 right_path->slots[right_level]);
5569 left_gen = btrfs_node_ptr_generation(
5570 left_path->nodes[left_level],
5571 left_path->slots[left_level]);
5572 right_gen = btrfs_node_ptr_generation(
5573 right_path->nodes[right_level],
5574 right_path->slots[right_level]);
5575 if (left_blockptr == right_blockptr &&
5576 left_gen == right_gen) {
5578 * As we're on a shared block, don't
5579 * allow to go deeper.
5581 advance_left = ADVANCE_ONLY_NEXT;
5582 advance_right = ADVANCE_ONLY_NEXT;
5584 advance_left = ADVANCE;
5585 advance_right = ADVANCE;
5588 } else if (left_level < right_level) {
5589 advance_right = ADVANCE;
5591 advance_left = ADVANCE;
5596 btrfs_free_path(left_path);
5597 btrfs_free_path(right_path);
5603 * this is similar to btrfs_next_leaf, but does not try to preserve
5604 * and fixup the path. It looks for and returns the next key in the
5605 * tree based on the current path and the min_trans parameters.
5607 * 0 is returned if another key is found, < 0 if there are any errors
5608 * and 1 is returned if there are no higher keys in the tree
5610 * path->keep_locks should be set to 1 on the search made before
5611 * calling this function.
5613 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5614 struct btrfs_key *key, int level, u64 min_trans)
5617 struct extent_buffer *c;
5619 WARN_ON(!path->keep_locks);
5620 while (level < BTRFS_MAX_LEVEL) {
5621 if (!path->nodes[level])
5624 slot = path->slots[level] + 1;
5625 c = path->nodes[level];
5627 if (slot >= btrfs_header_nritems(c)) {
5630 struct btrfs_key cur_key;
5631 if (level + 1 >= BTRFS_MAX_LEVEL ||
5632 !path->nodes[level + 1])
5635 if (path->locks[level + 1]) {
5640 slot = btrfs_header_nritems(c) - 1;
5642 btrfs_item_key_to_cpu(c, &cur_key, slot);
5644 btrfs_node_key_to_cpu(c, &cur_key, slot);
5646 orig_lowest = path->lowest_level;
5647 btrfs_release_path(path);
5648 path->lowest_level = level;
5649 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5651 path->lowest_level = orig_lowest;
5655 c = path->nodes[level];
5656 slot = path->slots[level];
5663 btrfs_item_key_to_cpu(c, key, slot);
5665 u64 gen = btrfs_node_ptr_generation(c, slot);
5667 if (gen < min_trans) {
5671 btrfs_node_key_to_cpu(c, key, slot);
5679 * search the tree again to find a leaf with greater keys
5680 * returns 0 if it found something or 1 if there are no greater leaves.
5681 * returns < 0 on io errors.
5683 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5685 return btrfs_next_old_leaf(root, path, 0);
5688 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5693 struct extent_buffer *c;
5694 struct extent_buffer *next;
5695 struct btrfs_key key;
5698 int old_spinning = path->leave_spinning;
5699 int next_rw_lock = 0;
5701 nritems = btrfs_header_nritems(path->nodes[0]);
5705 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5710 btrfs_release_path(path);
5712 path->keep_locks = 1;
5713 path->leave_spinning = 1;
5716 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5718 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5719 path->keep_locks = 0;
5724 nritems = btrfs_header_nritems(path->nodes[0]);
5726 * by releasing the path above we dropped all our locks. A balance
5727 * could have added more items next to the key that used to be
5728 * at the very end of the block. So, check again here and
5729 * advance the path if there are now more items available.
5731 if (nritems > 0 && path->slots[0] < nritems - 1) {
5738 * So the above check misses one case:
5739 * - after releasing the path above, someone has removed the item that
5740 * used to be at the very end of the block, and balance between leafs
5741 * gets another one with bigger key.offset to replace it.
5743 * This one should be returned as well, or we can get leaf corruption
5744 * later(esp. in __btrfs_drop_extents()).
5746 * And a bit more explanation about this check,
5747 * with ret > 0, the key isn't found, the path points to the slot
5748 * where it should be inserted, so the path->slots[0] item must be the
5751 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5756 while (level < BTRFS_MAX_LEVEL) {
5757 if (!path->nodes[level]) {
5762 slot = path->slots[level] + 1;
5763 c = path->nodes[level];
5764 if (slot >= btrfs_header_nritems(c)) {
5766 if (level == BTRFS_MAX_LEVEL) {
5774 btrfs_tree_unlock_rw(next, next_rw_lock);
5775 free_extent_buffer(next);
5779 next_rw_lock = path->locks[level];
5780 ret = read_block_for_search(root, path, &next, level,
5786 btrfs_release_path(path);
5790 if (!path->skip_locking) {
5791 ret = btrfs_try_tree_read_lock(next);
5792 if (!ret && time_seq) {
5794 * If we don't get the lock, we may be racing
5795 * with push_leaf_left, holding that lock while
5796 * itself waiting for the leaf we've currently
5797 * locked. To solve this situation, we give up
5798 * on our lock and cycle.
5800 free_extent_buffer(next);
5801 btrfs_release_path(path);
5806 btrfs_set_path_blocking(path);
5807 btrfs_tree_read_lock(next);
5809 next_rw_lock = BTRFS_READ_LOCK;
5813 path->slots[level] = slot;
5816 c = path->nodes[level];
5817 if (path->locks[level])
5818 btrfs_tree_unlock_rw(c, path->locks[level]);
5820 free_extent_buffer(c);
5821 path->nodes[level] = next;
5822 path->slots[level] = 0;
5823 if (!path->skip_locking)
5824 path->locks[level] = next_rw_lock;
5828 ret = read_block_for_search(root, path, &next, level,
5834 btrfs_release_path(path);
5838 if (!path->skip_locking) {
5839 ret = btrfs_try_tree_read_lock(next);
5841 btrfs_set_path_blocking(path);
5842 btrfs_tree_read_lock(next);
5844 next_rw_lock = BTRFS_READ_LOCK;
5849 unlock_up(path, 0, 1, 0, NULL);
5850 path->leave_spinning = old_spinning;
5852 btrfs_set_path_blocking(path);
5858 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5859 * searching until it gets past min_objectid or finds an item of 'type'
5861 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5863 int btrfs_previous_item(struct btrfs_root *root,
5864 struct btrfs_path *path, u64 min_objectid,
5867 struct btrfs_key found_key;
5868 struct extent_buffer *leaf;
5873 if (path->slots[0] == 0) {
5874 btrfs_set_path_blocking(path);
5875 ret = btrfs_prev_leaf(root, path);
5881 leaf = path->nodes[0];
5882 nritems = btrfs_header_nritems(leaf);
5885 if (path->slots[0] == nritems)
5888 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5889 if (found_key.objectid < min_objectid)
5891 if (found_key.type == type)
5893 if (found_key.objectid == min_objectid &&
5894 found_key.type < type)
5901 * search in extent tree to find a previous Metadata/Data extent item with
5904 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5906 int btrfs_previous_extent_item(struct btrfs_root *root,
5907 struct btrfs_path *path, u64 min_objectid)
5909 struct btrfs_key found_key;
5910 struct extent_buffer *leaf;
5915 if (path->slots[0] == 0) {
5916 btrfs_set_path_blocking(path);
5917 ret = btrfs_prev_leaf(root, path);
5923 leaf = path->nodes[0];
5924 nritems = btrfs_header_nritems(leaf);
5927 if (path->slots[0] == nritems)
5930 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5931 if (found_key.objectid < min_objectid)
5933 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5934 found_key.type == BTRFS_METADATA_ITEM_KEY)
5936 if (found_key.objectid == min_objectid &&
5937 found_key.type < BTRFS_EXTENT_ITEM_KEY)