2 * Copyright (C) 2007,2008 Oracle. All rights reserved.
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
19 #include <linux/sched.h>
20 #include <linux/slab.h>
21 #include <linux/rbtree.h>
24 #include "transaction.h"
25 #include "print-tree.h"
28 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
29 *root, struct btrfs_path *path, int level);
30 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
31 *root, struct btrfs_key *ins_key,
32 struct btrfs_path *path, int data_size, int extend);
33 static int push_node_left(struct btrfs_trans_handle *trans,
34 struct btrfs_root *root, struct extent_buffer *dst,
35 struct extent_buffer *src, int empty);
36 static int balance_node_right(struct btrfs_trans_handle *trans,
37 struct btrfs_root *root,
38 struct extent_buffer *dst_buf,
39 struct extent_buffer *src_buf);
40 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
42 static int tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
43 struct extent_buffer *eb);
45 struct btrfs_path *btrfs_alloc_path(void)
47 struct btrfs_path *path;
48 path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
53 * set all locked nodes in the path to blocking locks. This should
54 * be done before scheduling
56 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
59 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
60 if (!p->nodes[i] || !p->locks[i])
62 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
63 if (p->locks[i] == BTRFS_READ_LOCK)
64 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
65 else if (p->locks[i] == BTRFS_WRITE_LOCK)
66 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
71 * reset all the locked nodes in the patch to spinning locks.
73 * held is used to keep lockdep happy, when lockdep is enabled
74 * we set held to a blocking lock before we go around and
75 * retake all the spinlocks in the path. You can safely use NULL
78 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
79 struct extent_buffer *held, int held_rw)
84 btrfs_set_lock_blocking_rw(held, held_rw);
85 if (held_rw == BTRFS_WRITE_LOCK)
86 held_rw = BTRFS_WRITE_LOCK_BLOCKING;
87 else if (held_rw == BTRFS_READ_LOCK)
88 held_rw = BTRFS_READ_LOCK_BLOCKING;
90 btrfs_set_path_blocking(p);
92 for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
93 if (p->nodes[i] && p->locks[i]) {
94 btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
95 if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
96 p->locks[i] = BTRFS_WRITE_LOCK;
97 else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
98 p->locks[i] = BTRFS_READ_LOCK;
103 btrfs_clear_lock_blocking_rw(held, held_rw);
106 /* this also releases the path */
107 void btrfs_free_path(struct btrfs_path *p)
111 btrfs_release_path(p);
112 kmem_cache_free(btrfs_path_cachep, p);
116 * path release drops references on the extent buffers in the path
117 * and it drops any locks held by this path
119 * It is safe to call this on paths that no locks or extent buffers held.
121 noinline void btrfs_release_path(struct btrfs_path *p)
125 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
130 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
133 free_extent_buffer(p->nodes[i]);
139 * safely gets a reference on the root node of a tree. A lock
140 * is not taken, so a concurrent writer may put a different node
141 * at the root of the tree. See btrfs_lock_root_node for the
144 * The extent buffer returned by this has a reference taken, so
145 * it won't disappear. It may stop being the root of the tree
146 * at any time because there are no locks held.
148 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
150 struct extent_buffer *eb;
154 eb = rcu_dereference(root->node);
157 * RCU really hurts here, we could free up the root node because
158 * it was cow'ed but we may not get the new root node yet so do
159 * the inc_not_zero dance and if it doesn't work then
160 * synchronize_rcu and try again.
162 if (atomic_inc_not_zero(&eb->refs)) {
172 /* loop around taking references on and locking the root node of the
173 * tree until you end up with a lock on the root. A locked buffer
174 * is returned, with a reference held.
176 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
178 struct extent_buffer *eb;
181 eb = btrfs_root_node(root);
183 if (eb == root->node)
185 btrfs_tree_unlock(eb);
186 free_extent_buffer(eb);
191 /* loop around taking references on and locking the root node of the
192 * tree until you end up with a lock on the root. A locked buffer
193 * is returned, with a reference held.
195 static struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
197 struct extent_buffer *eb;
200 eb = btrfs_root_node(root);
201 btrfs_tree_read_lock(eb);
202 if (eb == root->node)
204 btrfs_tree_read_unlock(eb);
205 free_extent_buffer(eb);
210 /* cowonly root (everything not a reference counted cow subvolume), just get
211 * put onto a simple dirty list. transaction.c walks this to make sure they
212 * get properly updated on disk.
214 static void add_root_to_dirty_list(struct btrfs_root *root)
216 spin_lock(&root->fs_info->trans_lock);
217 if (test_bit(BTRFS_ROOT_TRACK_DIRTY, &root->state) &&
218 list_empty(&root->dirty_list)) {
219 list_add(&root->dirty_list,
220 &root->fs_info->dirty_cowonly_roots);
222 spin_unlock(&root->fs_info->trans_lock);
226 * used by snapshot creation to make a copy of a root for a tree with
227 * a given objectid. The buffer with the new root node is returned in
228 * cow_ret, and this func returns zero on success or a negative error code.
230 int btrfs_copy_root(struct btrfs_trans_handle *trans,
231 struct btrfs_root *root,
232 struct extent_buffer *buf,
233 struct extent_buffer **cow_ret, u64 new_root_objectid)
235 struct extent_buffer *cow;
238 struct btrfs_disk_key disk_key;
240 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
241 trans->transid != root->fs_info->running_transaction->transid);
242 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
243 trans->transid != root->last_trans);
245 level = btrfs_header_level(buf);
247 btrfs_item_key(buf, &disk_key, 0);
249 btrfs_node_key(buf, &disk_key, 0);
251 cow = btrfs_alloc_tree_block(trans, root, 0, new_root_objectid,
252 &disk_key, level, buf->start, 0);
256 copy_extent_buffer(cow, buf, 0, 0, cow->len);
257 btrfs_set_header_bytenr(cow, cow->start);
258 btrfs_set_header_generation(cow, trans->transid);
259 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
260 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
261 BTRFS_HEADER_FLAG_RELOC);
262 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
263 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
265 btrfs_set_header_owner(cow, new_root_objectid);
267 write_extent_buffer(cow, root->fs_info->fsid, btrfs_header_fsid(),
270 WARN_ON(btrfs_header_generation(buf) > trans->transid);
271 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
272 ret = btrfs_inc_ref(trans, root, cow, 1);
274 ret = btrfs_inc_ref(trans, root, cow, 0);
279 btrfs_mark_buffer_dirty(cow);
288 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
289 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
291 MOD_LOG_ROOT_REPLACE,
294 struct tree_mod_move {
299 struct tree_mod_root {
304 struct tree_mod_elem {
306 u64 index; /* shifted logical */
310 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
313 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
316 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
317 struct btrfs_disk_key key;
320 /* this is used for op == MOD_LOG_MOVE_KEYS */
321 struct tree_mod_move move;
323 /* this is used for op == MOD_LOG_ROOT_REPLACE */
324 struct tree_mod_root old_root;
327 static inline void tree_mod_log_read_lock(struct btrfs_fs_info *fs_info)
329 read_lock(&fs_info->tree_mod_log_lock);
332 static inline void tree_mod_log_read_unlock(struct btrfs_fs_info *fs_info)
334 read_unlock(&fs_info->tree_mod_log_lock);
337 static inline void tree_mod_log_write_lock(struct btrfs_fs_info *fs_info)
339 write_lock(&fs_info->tree_mod_log_lock);
342 static inline void tree_mod_log_write_unlock(struct btrfs_fs_info *fs_info)
344 write_unlock(&fs_info->tree_mod_log_lock);
348 * Pull a new tree mod seq number for our operation.
350 static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
352 return atomic64_inc_return(&fs_info->tree_mod_seq);
356 * This adds a new blocker to the tree mod log's blocker list if the @elem
357 * passed does not already have a sequence number set. So when a caller expects
358 * to record tree modifications, it should ensure to set elem->seq to zero
359 * before calling btrfs_get_tree_mod_seq.
360 * Returns a fresh, unused tree log modification sequence number, even if no new
363 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
364 struct seq_list *elem)
366 tree_mod_log_write_lock(fs_info);
367 spin_lock(&fs_info->tree_mod_seq_lock);
369 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
370 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
372 spin_unlock(&fs_info->tree_mod_seq_lock);
373 tree_mod_log_write_unlock(fs_info);
378 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
379 struct seq_list *elem)
381 struct rb_root *tm_root;
382 struct rb_node *node;
383 struct rb_node *next;
384 struct seq_list *cur_elem;
385 struct tree_mod_elem *tm;
386 u64 min_seq = (u64)-1;
387 u64 seq_putting = elem->seq;
392 spin_lock(&fs_info->tree_mod_seq_lock);
393 list_del(&elem->list);
396 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
397 if (cur_elem->seq < min_seq) {
398 if (seq_putting > cur_elem->seq) {
400 * blocker with lower sequence number exists, we
401 * cannot remove anything from the log
403 spin_unlock(&fs_info->tree_mod_seq_lock);
406 min_seq = cur_elem->seq;
409 spin_unlock(&fs_info->tree_mod_seq_lock);
412 * anything that's lower than the lowest existing (read: blocked)
413 * sequence number can be removed from the tree.
415 tree_mod_log_write_lock(fs_info);
416 tm_root = &fs_info->tree_mod_log;
417 for (node = rb_first(tm_root); node; node = next) {
418 next = rb_next(node);
419 tm = container_of(node, struct tree_mod_elem, node);
420 if (tm->seq > min_seq)
422 rb_erase(node, tm_root);
425 tree_mod_log_write_unlock(fs_info);
429 * key order of the log:
432 * the index is the shifted logical of the *new* root node for root replace
433 * operations, or the shifted logical of the affected block for all other
436 * Note: must be called with write lock (tree_mod_log_write_lock).
439 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
441 struct rb_root *tm_root;
442 struct rb_node **new;
443 struct rb_node *parent = NULL;
444 struct tree_mod_elem *cur;
448 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
450 tm_root = &fs_info->tree_mod_log;
451 new = &tm_root->rb_node;
453 cur = container_of(*new, struct tree_mod_elem, node);
455 if (cur->index < tm->index)
456 new = &((*new)->rb_left);
457 else if (cur->index > tm->index)
458 new = &((*new)->rb_right);
459 else if (cur->seq < tm->seq)
460 new = &((*new)->rb_left);
461 else if (cur->seq > tm->seq)
462 new = &((*new)->rb_right);
467 rb_link_node(&tm->node, parent, new);
468 rb_insert_color(&tm->node, tm_root);
473 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
474 * returns zero with the tree_mod_log_lock acquired. The caller must hold
475 * this until all tree mod log insertions are recorded in the rb tree and then
476 * call tree_mod_log_write_unlock() to release.
478 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
479 struct extent_buffer *eb) {
481 if (list_empty(&(fs_info)->tree_mod_seq_list))
483 if (eb && btrfs_header_level(eb) == 0)
486 tree_mod_log_write_lock(fs_info);
487 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
488 tree_mod_log_write_unlock(fs_info);
495 /* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
496 static inline int tree_mod_need_log(const struct btrfs_fs_info *fs_info,
497 struct extent_buffer *eb)
500 if (list_empty(&(fs_info)->tree_mod_seq_list))
502 if (eb && btrfs_header_level(eb) == 0)
508 static struct tree_mod_elem *
509 alloc_tree_mod_elem(struct extent_buffer *eb, int slot,
510 enum mod_log_op op, gfp_t flags)
512 struct tree_mod_elem *tm;
514 tm = kzalloc(sizeof(*tm), flags);
518 tm->index = eb->start >> PAGE_CACHE_SHIFT;
519 if (op != MOD_LOG_KEY_ADD) {
520 btrfs_node_key(eb, &tm->key, slot);
521 tm->blockptr = btrfs_node_blockptr(eb, slot);
525 tm->generation = btrfs_node_ptr_generation(eb, slot);
526 RB_CLEAR_NODE(&tm->node);
532 tree_mod_log_insert_key(struct btrfs_fs_info *fs_info,
533 struct extent_buffer *eb, int slot,
534 enum mod_log_op op, gfp_t flags)
536 struct tree_mod_elem *tm;
539 if (!tree_mod_need_log(fs_info, eb))
542 tm = alloc_tree_mod_elem(eb, slot, op, flags);
546 if (tree_mod_dont_log(fs_info, eb)) {
551 ret = __tree_mod_log_insert(fs_info, tm);
552 tree_mod_log_write_unlock(fs_info);
560 tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
561 struct extent_buffer *eb, int dst_slot, int src_slot,
562 int nr_items, gfp_t flags)
564 struct tree_mod_elem *tm = NULL;
565 struct tree_mod_elem **tm_list = NULL;
570 if (!tree_mod_need_log(fs_info, eb))
573 tm_list = kzalloc(nr_items * sizeof(struct tree_mod_elem *), flags);
577 tm = kzalloc(sizeof(*tm), flags);
583 tm->index = eb->start >> PAGE_CACHE_SHIFT;
585 tm->move.dst_slot = dst_slot;
586 tm->move.nr_items = nr_items;
587 tm->op = MOD_LOG_MOVE_KEYS;
589 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
590 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
591 MOD_LOG_KEY_REMOVE_WHILE_MOVING, flags);
598 if (tree_mod_dont_log(fs_info, eb))
603 * When we override something during the move, we log these removals.
604 * This can only happen when we move towards the beginning of the
605 * buffer, i.e. dst_slot < src_slot.
607 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
608 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
613 ret = __tree_mod_log_insert(fs_info, tm);
616 tree_mod_log_write_unlock(fs_info);
621 for (i = 0; i < nr_items; i++) {
622 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
623 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
627 tree_mod_log_write_unlock(fs_info);
635 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
636 struct tree_mod_elem **tm_list,
642 for (i = nritems - 1; i >= 0; i--) {
643 ret = __tree_mod_log_insert(fs_info, tm_list[i]);
645 for (j = nritems - 1; j > i; j--)
646 rb_erase(&tm_list[j]->node,
647 &fs_info->tree_mod_log);
656 tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
657 struct extent_buffer *old_root,
658 struct extent_buffer *new_root, gfp_t flags,
661 struct tree_mod_elem *tm = NULL;
662 struct tree_mod_elem **tm_list = NULL;
667 if (!tree_mod_need_log(fs_info, NULL))
670 if (log_removal && btrfs_header_level(old_root) > 0) {
671 nritems = btrfs_header_nritems(old_root);
672 tm_list = kzalloc(nritems * sizeof(struct tree_mod_elem *),
678 for (i = 0; i < nritems; i++) {
679 tm_list[i] = alloc_tree_mod_elem(old_root, i,
680 MOD_LOG_KEY_REMOVE_WHILE_FREEING, flags);
688 tm = kzalloc(sizeof(*tm), flags);
694 tm->index = new_root->start >> PAGE_CACHE_SHIFT;
695 tm->old_root.logical = old_root->start;
696 tm->old_root.level = btrfs_header_level(old_root);
697 tm->generation = btrfs_header_generation(old_root);
698 tm->op = MOD_LOG_ROOT_REPLACE;
700 if (tree_mod_dont_log(fs_info, NULL))
704 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
706 ret = __tree_mod_log_insert(fs_info, tm);
708 tree_mod_log_write_unlock(fs_info);
717 for (i = 0; i < nritems; i++)
726 static struct tree_mod_elem *
727 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
730 struct rb_root *tm_root;
731 struct rb_node *node;
732 struct tree_mod_elem *cur = NULL;
733 struct tree_mod_elem *found = NULL;
734 u64 index = start >> PAGE_CACHE_SHIFT;
736 tree_mod_log_read_lock(fs_info);
737 tm_root = &fs_info->tree_mod_log;
738 node = tm_root->rb_node;
740 cur = container_of(node, struct tree_mod_elem, node);
741 if (cur->index < index) {
742 node = node->rb_left;
743 } else if (cur->index > index) {
744 node = node->rb_right;
745 } else if (cur->seq < min_seq) {
746 node = node->rb_left;
747 } else if (!smallest) {
748 /* we want the node with the highest seq */
750 BUG_ON(found->seq > cur->seq);
752 node = node->rb_left;
753 } else if (cur->seq > min_seq) {
754 /* we want the node with the smallest seq */
756 BUG_ON(found->seq < cur->seq);
758 node = node->rb_right;
764 tree_mod_log_read_unlock(fs_info);
770 * this returns the element from the log with the smallest time sequence
771 * value that's in the log (the oldest log item). any element with a time
772 * sequence lower than min_seq will be ignored.
774 static struct tree_mod_elem *
775 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
778 return __tree_mod_log_search(fs_info, start, min_seq, 1);
782 * this returns the element from the log with the largest time sequence
783 * value that's in the log (the most recent log item). any element with
784 * a time sequence lower than min_seq will be ignored.
786 static struct tree_mod_elem *
787 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
789 return __tree_mod_log_search(fs_info, start, min_seq, 0);
793 tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
794 struct extent_buffer *src, unsigned long dst_offset,
795 unsigned long src_offset, int nr_items)
798 struct tree_mod_elem **tm_list = NULL;
799 struct tree_mod_elem **tm_list_add, **tm_list_rem;
803 if (!tree_mod_need_log(fs_info, NULL))
806 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
809 tm_list = kzalloc(nr_items * 2 * sizeof(struct tree_mod_elem *),
814 tm_list_add = tm_list;
815 tm_list_rem = tm_list + nr_items;
816 for (i = 0; i < nr_items; i++) {
817 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
818 MOD_LOG_KEY_REMOVE, GFP_NOFS);
819 if (!tm_list_rem[i]) {
824 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
825 MOD_LOG_KEY_ADD, GFP_NOFS);
826 if (!tm_list_add[i]) {
832 if (tree_mod_dont_log(fs_info, NULL))
836 for (i = 0; i < nr_items; i++) {
837 ret = __tree_mod_log_insert(fs_info, tm_list_rem[i]);
840 ret = __tree_mod_log_insert(fs_info, tm_list_add[i]);
845 tree_mod_log_write_unlock(fs_info);
851 for (i = 0; i < nr_items * 2; i++) {
852 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
853 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
857 tree_mod_log_write_unlock(fs_info);
864 tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
865 int dst_offset, int src_offset, int nr_items)
868 ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
874 tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
875 struct extent_buffer *eb, int slot, int atomic)
879 ret = tree_mod_log_insert_key(fs_info, eb, slot,
881 atomic ? GFP_ATOMIC : GFP_NOFS);
886 tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
888 struct tree_mod_elem **tm_list = NULL;
893 if (btrfs_header_level(eb) == 0)
896 if (!tree_mod_need_log(fs_info, NULL))
899 nritems = btrfs_header_nritems(eb);
900 tm_list = kzalloc(nritems * sizeof(struct tree_mod_elem *),
905 for (i = 0; i < nritems; i++) {
906 tm_list[i] = alloc_tree_mod_elem(eb, i,
907 MOD_LOG_KEY_REMOVE_WHILE_FREEING, GFP_NOFS);
914 if (tree_mod_dont_log(fs_info, eb))
917 ret = __tree_mod_log_free_eb(fs_info, tm_list, nritems);
918 tree_mod_log_write_unlock(fs_info);
926 for (i = 0; i < nritems; i++)
934 tree_mod_log_set_root_pointer(struct btrfs_root *root,
935 struct extent_buffer *new_root_node,
939 ret = tree_mod_log_insert_root(root->fs_info, root->node,
940 new_root_node, GFP_NOFS, log_removal);
945 * check if the tree block can be shared by multiple trees
947 int btrfs_block_can_be_shared(struct btrfs_root *root,
948 struct extent_buffer *buf)
951 * Tree blocks not in refernece counted trees and tree roots
952 * are never shared. If a block was allocated after the last
953 * snapshot and the block was not allocated by tree relocation,
954 * we know the block is not shared.
956 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
957 buf != root->node && buf != root->commit_root &&
958 (btrfs_header_generation(buf) <=
959 btrfs_root_last_snapshot(&root->root_item) ||
960 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
962 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
963 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
964 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
970 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
971 struct btrfs_root *root,
972 struct extent_buffer *buf,
973 struct extent_buffer *cow,
983 * Backrefs update rules:
985 * Always use full backrefs for extent pointers in tree block
986 * allocated by tree relocation.
988 * If a shared tree block is no longer referenced by its owner
989 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
990 * use full backrefs for extent pointers in tree block.
992 * If a tree block is been relocating
993 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
994 * use full backrefs for extent pointers in tree block.
995 * The reason for this is some operations (such as drop tree)
996 * are only allowed for blocks use full backrefs.
999 if (btrfs_block_can_be_shared(root, buf)) {
1000 ret = btrfs_lookup_extent_info(trans, root, buf->start,
1001 btrfs_header_level(buf), 1,
1007 btrfs_std_error(root->fs_info, ret);
1012 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1013 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1014 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
1019 owner = btrfs_header_owner(buf);
1020 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
1021 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
1024 if ((owner == root->root_key.objectid ||
1025 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
1026 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
1027 ret = btrfs_inc_ref(trans, root, buf, 1);
1028 BUG_ON(ret); /* -ENOMEM */
1030 if (root->root_key.objectid ==
1031 BTRFS_TREE_RELOC_OBJECTID) {
1032 ret = btrfs_dec_ref(trans, root, buf, 0);
1033 BUG_ON(ret); /* -ENOMEM */
1034 ret = btrfs_inc_ref(trans, root, cow, 1);
1035 BUG_ON(ret); /* -ENOMEM */
1037 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
1040 if (root->root_key.objectid ==
1041 BTRFS_TREE_RELOC_OBJECTID)
1042 ret = btrfs_inc_ref(trans, root, cow, 1);
1044 ret = btrfs_inc_ref(trans, root, cow, 0);
1045 BUG_ON(ret); /* -ENOMEM */
1047 if (new_flags != 0) {
1048 int level = btrfs_header_level(buf);
1050 ret = btrfs_set_disk_extent_flags(trans, root,
1053 new_flags, level, 0);
1058 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
1059 if (root->root_key.objectid ==
1060 BTRFS_TREE_RELOC_OBJECTID)
1061 ret = btrfs_inc_ref(trans, root, cow, 1);
1063 ret = btrfs_inc_ref(trans, root, cow, 0);
1064 BUG_ON(ret); /* -ENOMEM */
1065 ret = btrfs_dec_ref(trans, root, buf, 1);
1066 BUG_ON(ret); /* -ENOMEM */
1068 clean_tree_block(trans, root, buf);
1075 * does the dirty work in cow of a single block. The parent block (if
1076 * supplied) is updated to point to the new cow copy. The new buffer is marked
1077 * dirty and returned locked. If you modify the block it needs to be marked
1080 * search_start -- an allocation hint for the new block
1082 * empty_size -- a hint that you plan on doing more cow. This is the size in
1083 * bytes the allocator should try to find free next to the block it returns.
1084 * This is just a hint and may be ignored by the allocator.
1086 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
1087 struct btrfs_root *root,
1088 struct extent_buffer *buf,
1089 struct extent_buffer *parent, int parent_slot,
1090 struct extent_buffer **cow_ret,
1091 u64 search_start, u64 empty_size)
1093 struct btrfs_disk_key disk_key;
1094 struct extent_buffer *cow;
1097 int unlock_orig = 0;
1100 if (*cow_ret == buf)
1103 btrfs_assert_tree_locked(buf);
1105 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1106 trans->transid != root->fs_info->running_transaction->transid);
1107 WARN_ON(test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
1108 trans->transid != root->last_trans);
1110 level = btrfs_header_level(buf);
1113 btrfs_item_key(buf, &disk_key, 0);
1115 btrfs_node_key(buf, &disk_key, 0);
1117 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
1119 parent_start = parent->start;
1125 cow = btrfs_alloc_tree_block(trans, root, parent_start,
1126 root->root_key.objectid, &disk_key, level,
1127 search_start, empty_size);
1129 return PTR_ERR(cow);
1131 /* cow is set to blocking by btrfs_init_new_buffer */
1133 copy_extent_buffer(cow, buf, 0, 0, cow->len);
1134 btrfs_set_header_bytenr(cow, cow->start);
1135 btrfs_set_header_generation(cow, trans->transid);
1136 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
1137 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1138 BTRFS_HEADER_FLAG_RELOC);
1139 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1140 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1142 btrfs_set_header_owner(cow, root->root_key.objectid);
1144 write_extent_buffer(cow, root->fs_info->fsid, btrfs_header_fsid(),
1147 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1149 btrfs_abort_transaction(trans, root, ret);
1153 if (test_bit(BTRFS_ROOT_REF_COWS, &root->state)) {
1154 ret = btrfs_reloc_cow_block(trans, root, buf, cow);
1159 if (buf == root->node) {
1160 WARN_ON(parent && parent != buf);
1161 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1162 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1163 parent_start = buf->start;
1167 extent_buffer_get(cow);
1168 tree_mod_log_set_root_pointer(root, cow, 1);
1169 rcu_assign_pointer(root->node, cow);
1171 btrfs_free_tree_block(trans, root, buf, parent_start,
1173 free_extent_buffer(buf);
1174 add_root_to_dirty_list(root);
1176 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1177 parent_start = parent->start;
1181 WARN_ON(trans->transid != btrfs_header_generation(parent));
1182 tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
1183 MOD_LOG_KEY_REPLACE, GFP_NOFS);
1184 btrfs_set_node_blockptr(parent, parent_slot,
1186 btrfs_set_node_ptr_generation(parent, parent_slot,
1188 btrfs_mark_buffer_dirty(parent);
1190 ret = tree_mod_log_free_eb(root->fs_info, buf);
1192 btrfs_abort_transaction(trans, root, ret);
1196 btrfs_free_tree_block(trans, root, buf, parent_start,
1200 btrfs_tree_unlock(buf);
1201 free_extent_buffer_stale(buf);
1202 btrfs_mark_buffer_dirty(cow);
1208 * returns the logical address of the oldest predecessor of the given root.
1209 * entries older than time_seq are ignored.
1211 static struct tree_mod_elem *
1212 __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1213 struct extent_buffer *eb_root, u64 time_seq)
1215 struct tree_mod_elem *tm;
1216 struct tree_mod_elem *found = NULL;
1217 u64 root_logical = eb_root->start;
1224 * the very last operation that's logged for a root is the replacement
1225 * operation (if it is replaced at all). this has the index of the *new*
1226 * root, making it the very first operation that's logged for this root.
1229 tm = tree_mod_log_search_oldest(fs_info, root_logical,
1234 * if there are no tree operation for the oldest root, we simply
1235 * return it. this should only happen if that (old) root is at
1242 * if there's an operation that's not a root replacement, we
1243 * found the oldest version of our root. normally, we'll find a
1244 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1246 if (tm->op != MOD_LOG_ROOT_REPLACE)
1250 root_logical = tm->old_root.logical;
1254 /* if there's no old root to return, return what we found instead */
1262 * tm is a pointer to the first operation to rewind within eb. then, all
1263 * previous operations will be rewinded (until we reach something older than
1267 __tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1268 u64 time_seq, struct tree_mod_elem *first_tm)
1271 struct rb_node *next;
1272 struct tree_mod_elem *tm = first_tm;
1273 unsigned long o_dst;
1274 unsigned long o_src;
1275 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1277 n = btrfs_header_nritems(eb);
1278 tree_mod_log_read_lock(fs_info);
1279 while (tm && tm->seq >= time_seq) {
1281 * all the operations are recorded with the operator used for
1282 * the modification. as we're going backwards, we do the
1283 * opposite of each operation here.
1286 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1287 BUG_ON(tm->slot < n);
1289 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1290 case MOD_LOG_KEY_REMOVE:
1291 btrfs_set_node_key(eb, &tm->key, tm->slot);
1292 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1293 btrfs_set_node_ptr_generation(eb, tm->slot,
1297 case MOD_LOG_KEY_REPLACE:
1298 BUG_ON(tm->slot >= n);
1299 btrfs_set_node_key(eb, &tm->key, tm->slot);
1300 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1301 btrfs_set_node_ptr_generation(eb, tm->slot,
1304 case MOD_LOG_KEY_ADD:
1305 /* if a move operation is needed it's in the log */
1308 case MOD_LOG_MOVE_KEYS:
1309 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1310 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1311 memmove_extent_buffer(eb, o_dst, o_src,
1312 tm->move.nr_items * p_size);
1314 case MOD_LOG_ROOT_REPLACE:
1316 * this operation is special. for roots, this must be
1317 * handled explicitly before rewinding.
1318 * for non-roots, this operation may exist if the node
1319 * was a root: root A -> child B; then A gets empty and
1320 * B is promoted to the new root. in the mod log, we'll
1321 * have a root-replace operation for B, a tree block
1322 * that is no root. we simply ignore that operation.
1326 next = rb_next(&tm->node);
1329 tm = container_of(next, struct tree_mod_elem, node);
1330 if (tm->index != first_tm->index)
1333 tree_mod_log_read_unlock(fs_info);
1334 btrfs_set_header_nritems(eb, n);
1338 * Called with eb read locked. If the buffer cannot be rewinded, the same buffer
1339 * is returned. If rewind operations happen, a fresh buffer is returned. The
1340 * returned buffer is always read-locked. If the returned buffer is not the
1341 * input buffer, the lock on the input buffer is released and the input buffer
1342 * is freed (its refcount is decremented).
1344 static struct extent_buffer *
1345 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct btrfs_path *path,
1346 struct extent_buffer *eb, u64 time_seq)
1348 struct extent_buffer *eb_rewin;
1349 struct tree_mod_elem *tm;
1354 if (btrfs_header_level(eb) == 0)
1357 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1361 btrfs_set_path_blocking(path);
1362 btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
1364 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1365 BUG_ON(tm->slot != 0);
1366 eb_rewin = alloc_dummy_extent_buffer(eb->start,
1367 fs_info->tree_root->nodesize);
1369 btrfs_tree_read_unlock_blocking(eb);
1370 free_extent_buffer(eb);
1373 btrfs_set_header_bytenr(eb_rewin, eb->start);
1374 btrfs_set_header_backref_rev(eb_rewin,
1375 btrfs_header_backref_rev(eb));
1376 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1377 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1379 eb_rewin = btrfs_clone_extent_buffer(eb);
1381 btrfs_tree_read_unlock_blocking(eb);
1382 free_extent_buffer(eb);
1387 btrfs_clear_path_blocking(path, NULL, BTRFS_READ_LOCK);
1388 btrfs_tree_read_unlock_blocking(eb);
1389 free_extent_buffer(eb);
1391 extent_buffer_get(eb_rewin);
1392 btrfs_tree_read_lock(eb_rewin);
1393 __tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
1394 WARN_ON(btrfs_header_nritems(eb_rewin) >
1395 BTRFS_NODEPTRS_PER_BLOCK(fs_info->tree_root));
1401 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1402 * value. If there are no changes, the current root->root_node is returned. If
1403 * anything changed in between, there's a fresh buffer allocated on which the
1404 * rewind operations are done. In any case, the returned buffer is read locked.
1405 * Returns NULL on error (with no locks held).
1407 static inline struct extent_buffer *
1408 get_old_root(struct btrfs_root *root, u64 time_seq)
1410 struct tree_mod_elem *tm;
1411 struct extent_buffer *eb = NULL;
1412 struct extent_buffer *eb_root;
1413 struct extent_buffer *old;
1414 struct tree_mod_root *old_root = NULL;
1415 u64 old_generation = 0;
1418 eb_root = btrfs_read_lock_root_node(root);
1419 tm = __tree_mod_log_oldest_root(root->fs_info, eb_root, time_seq);
1423 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1424 old_root = &tm->old_root;
1425 old_generation = tm->generation;
1426 logical = old_root->logical;
1428 logical = eb_root->start;
1431 tm = tree_mod_log_search(root->fs_info, logical, time_seq);
1432 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1433 btrfs_tree_read_unlock(eb_root);
1434 free_extent_buffer(eb_root);
1435 old = read_tree_block(root, logical, 0);
1436 if (WARN_ON(!old || !extent_buffer_uptodate(old))) {
1437 free_extent_buffer(old);
1438 btrfs_warn(root->fs_info,
1439 "failed to read tree block %llu from get_old_root", logical);
1441 eb = btrfs_clone_extent_buffer(old);
1442 free_extent_buffer(old);
1444 } else if (old_root) {
1445 btrfs_tree_read_unlock(eb_root);
1446 free_extent_buffer(eb_root);
1447 eb = alloc_dummy_extent_buffer(logical, root->nodesize);
1449 btrfs_set_lock_blocking_rw(eb_root, BTRFS_READ_LOCK);
1450 eb = btrfs_clone_extent_buffer(eb_root);
1451 btrfs_tree_read_unlock_blocking(eb_root);
1452 free_extent_buffer(eb_root);
1457 extent_buffer_get(eb);
1458 btrfs_tree_read_lock(eb);
1460 btrfs_set_header_bytenr(eb, eb->start);
1461 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1462 btrfs_set_header_owner(eb, btrfs_header_owner(eb_root));
1463 btrfs_set_header_level(eb, old_root->level);
1464 btrfs_set_header_generation(eb, old_generation);
1467 __tree_mod_log_rewind(root->fs_info, eb, time_seq, tm);
1469 WARN_ON(btrfs_header_level(eb) != 0);
1470 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(root));
1475 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1477 struct tree_mod_elem *tm;
1479 struct extent_buffer *eb_root = btrfs_root_node(root);
1481 tm = __tree_mod_log_oldest_root(root->fs_info, eb_root, time_seq);
1482 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1483 level = tm->old_root.level;
1485 level = btrfs_header_level(eb_root);
1487 free_extent_buffer(eb_root);
1492 static inline int should_cow_block(struct btrfs_trans_handle *trans,
1493 struct btrfs_root *root,
1494 struct extent_buffer *buf)
1496 if (btrfs_test_is_dummy_root(root))
1499 /* ensure we can see the force_cow */
1503 * We do not need to cow a block if
1504 * 1) this block is not created or changed in this transaction;
1505 * 2) this block does not belong to TREE_RELOC tree;
1506 * 3) the root is not forced COW.
1508 * What is forced COW:
1509 * when we create snapshot during commiting the transaction,
1510 * after we've finished coping src root, we must COW the shared
1511 * block to ensure the metadata consistency.
1513 if (btrfs_header_generation(buf) == trans->transid &&
1514 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1515 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1516 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1517 !test_bit(BTRFS_ROOT_FORCE_COW, &root->state))
1523 * cows a single block, see __btrfs_cow_block for the real work.
1524 * This version of it has extra checks so that a block isn't cow'd more than
1525 * once per transaction, as long as it hasn't been written yet
1527 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1528 struct btrfs_root *root, struct extent_buffer *buf,
1529 struct extent_buffer *parent, int parent_slot,
1530 struct extent_buffer **cow_ret)
1535 if (trans->transaction != root->fs_info->running_transaction)
1536 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1538 root->fs_info->running_transaction->transid);
1540 if (trans->transid != root->fs_info->generation)
1541 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1542 trans->transid, root->fs_info->generation);
1544 if (!should_cow_block(trans, root, buf)) {
1549 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
1552 btrfs_set_lock_blocking(parent);
1553 btrfs_set_lock_blocking(buf);
1555 ret = __btrfs_cow_block(trans, root, buf, parent,
1556 parent_slot, cow_ret, search_start, 0);
1558 trace_btrfs_cow_block(root, buf, *cow_ret);
1564 * helper function for defrag to decide if two blocks pointed to by a
1565 * node are actually close by
1567 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1569 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1571 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1577 * compare two keys in a memcmp fashion
1579 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
1581 struct btrfs_key k1;
1583 btrfs_disk_key_to_cpu(&k1, disk);
1585 return btrfs_comp_cpu_keys(&k1, k2);
1589 * same as comp_keys only with two btrfs_key's
1591 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
1593 if (k1->objectid > k2->objectid)
1595 if (k1->objectid < k2->objectid)
1597 if (k1->type > k2->type)
1599 if (k1->type < k2->type)
1601 if (k1->offset > k2->offset)
1603 if (k1->offset < k2->offset)
1609 * this is used by the defrag code to go through all the
1610 * leaves pointed to by a node and reallocate them so that
1611 * disk order is close to key order
1613 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1614 struct btrfs_root *root, struct extent_buffer *parent,
1615 int start_slot, u64 *last_ret,
1616 struct btrfs_key *progress)
1618 struct extent_buffer *cur;
1621 u64 search_start = *last_ret;
1631 int progress_passed = 0;
1632 struct btrfs_disk_key disk_key;
1634 parent_level = btrfs_header_level(parent);
1636 WARN_ON(trans->transaction != root->fs_info->running_transaction);
1637 WARN_ON(trans->transid != root->fs_info->generation);
1639 parent_nritems = btrfs_header_nritems(parent);
1640 blocksize = root->nodesize;
1641 end_slot = parent_nritems;
1643 if (parent_nritems == 1)
1646 btrfs_set_lock_blocking(parent);
1648 for (i = start_slot; i < end_slot; i++) {
1651 btrfs_node_key(parent, &disk_key, i);
1652 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1655 progress_passed = 1;
1656 blocknr = btrfs_node_blockptr(parent, i);
1657 gen = btrfs_node_ptr_generation(parent, i);
1658 if (last_block == 0)
1659 last_block = blocknr;
1662 other = btrfs_node_blockptr(parent, i - 1);
1663 close = close_blocks(blocknr, other, blocksize);
1665 if (!close && i < end_slot - 2) {
1666 other = btrfs_node_blockptr(parent, i + 1);
1667 close = close_blocks(blocknr, other, blocksize);
1670 last_block = blocknr;
1674 cur = btrfs_find_tree_block(root, blocknr);
1676 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1679 if (!cur || !uptodate) {
1681 cur = read_tree_block(root, blocknr, gen);
1682 if (!cur || !extent_buffer_uptodate(cur)) {
1683 free_extent_buffer(cur);
1686 } else if (!uptodate) {
1687 err = btrfs_read_buffer(cur, gen);
1689 free_extent_buffer(cur);
1694 if (search_start == 0)
1695 search_start = last_block;
1697 btrfs_tree_lock(cur);
1698 btrfs_set_lock_blocking(cur);
1699 err = __btrfs_cow_block(trans, root, cur, parent, i,
1702 (end_slot - i) * blocksize));
1704 btrfs_tree_unlock(cur);
1705 free_extent_buffer(cur);
1708 search_start = cur->start;
1709 last_block = cur->start;
1710 *last_ret = search_start;
1711 btrfs_tree_unlock(cur);
1712 free_extent_buffer(cur);
1718 * The leaf data grows from end-to-front in the node.
1719 * this returns the address of the start of the last item,
1720 * which is the stop of the leaf data stack
1722 static inline unsigned int leaf_data_end(struct btrfs_root *root,
1723 struct extent_buffer *leaf)
1725 u32 nr = btrfs_header_nritems(leaf);
1727 return BTRFS_LEAF_DATA_SIZE(root);
1728 return btrfs_item_offset_nr(leaf, nr - 1);
1733 * search for key in the extent_buffer. The items start at offset p,
1734 * and they are item_size apart. There are 'max' items in p.
1736 * the slot in the array is returned via slot, and it points to
1737 * the place where you would insert key if it is not found in
1740 * slot may point to max if the key is bigger than all of the keys
1742 static noinline int generic_bin_search(struct extent_buffer *eb,
1744 int item_size, struct btrfs_key *key,
1751 struct btrfs_disk_key *tmp = NULL;
1752 struct btrfs_disk_key unaligned;
1753 unsigned long offset;
1755 unsigned long map_start = 0;
1756 unsigned long map_len = 0;
1759 while (low < high) {
1760 mid = (low + high) / 2;
1761 offset = p + mid * item_size;
1763 if (!kaddr || offset < map_start ||
1764 (offset + sizeof(struct btrfs_disk_key)) >
1765 map_start + map_len) {
1767 err = map_private_extent_buffer(eb, offset,
1768 sizeof(struct btrfs_disk_key),
1769 &kaddr, &map_start, &map_len);
1772 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1775 read_extent_buffer(eb, &unaligned,
1776 offset, sizeof(unaligned));
1781 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1784 ret = comp_keys(tmp, key);
1800 * simple bin_search frontend that does the right thing for
1803 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1804 int level, int *slot)
1807 return generic_bin_search(eb,
1808 offsetof(struct btrfs_leaf, items),
1809 sizeof(struct btrfs_item),
1810 key, btrfs_header_nritems(eb),
1813 return generic_bin_search(eb,
1814 offsetof(struct btrfs_node, ptrs),
1815 sizeof(struct btrfs_key_ptr),
1816 key, btrfs_header_nritems(eb),
1820 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1821 int level, int *slot)
1823 return bin_search(eb, key, level, slot);
1826 static void root_add_used(struct btrfs_root *root, u32 size)
1828 spin_lock(&root->accounting_lock);
1829 btrfs_set_root_used(&root->root_item,
1830 btrfs_root_used(&root->root_item) + size);
1831 spin_unlock(&root->accounting_lock);
1834 static void root_sub_used(struct btrfs_root *root, u32 size)
1836 spin_lock(&root->accounting_lock);
1837 btrfs_set_root_used(&root->root_item,
1838 btrfs_root_used(&root->root_item) - size);
1839 spin_unlock(&root->accounting_lock);
1842 /* given a node and slot number, this reads the blocks it points to. The
1843 * extent buffer is returned with a reference taken (but unlocked).
1844 * NULL is returned on error.
1846 static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
1847 struct extent_buffer *parent, int slot)
1849 int level = btrfs_header_level(parent);
1850 struct extent_buffer *eb;
1854 if (slot >= btrfs_header_nritems(parent))
1859 eb = read_tree_block(root, btrfs_node_blockptr(parent, slot),
1860 btrfs_node_ptr_generation(parent, slot));
1861 if (eb && !extent_buffer_uptodate(eb)) {
1862 free_extent_buffer(eb);
1870 * node level balancing, used to make sure nodes are in proper order for
1871 * item deletion. We balance from the top down, so we have to make sure
1872 * that a deletion won't leave an node completely empty later on.
1874 static noinline int balance_level(struct btrfs_trans_handle *trans,
1875 struct btrfs_root *root,
1876 struct btrfs_path *path, int level)
1878 struct extent_buffer *right = NULL;
1879 struct extent_buffer *mid;
1880 struct extent_buffer *left = NULL;
1881 struct extent_buffer *parent = NULL;
1885 int orig_slot = path->slots[level];
1891 mid = path->nodes[level];
1893 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1894 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1895 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1897 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1899 if (level < BTRFS_MAX_LEVEL - 1) {
1900 parent = path->nodes[level + 1];
1901 pslot = path->slots[level + 1];
1905 * deal with the case where there is only one pointer in the root
1906 * by promoting the node below to a root
1909 struct extent_buffer *child;
1911 if (btrfs_header_nritems(mid) != 1)
1914 /* promote the child to a root */
1915 child = read_node_slot(root, mid, 0);
1918 btrfs_std_error(root->fs_info, ret);
1922 btrfs_tree_lock(child);
1923 btrfs_set_lock_blocking(child);
1924 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1926 btrfs_tree_unlock(child);
1927 free_extent_buffer(child);
1931 tree_mod_log_set_root_pointer(root, child, 1);
1932 rcu_assign_pointer(root->node, child);
1934 add_root_to_dirty_list(root);
1935 btrfs_tree_unlock(child);
1937 path->locks[level] = 0;
1938 path->nodes[level] = NULL;
1939 clean_tree_block(trans, root, mid);
1940 btrfs_tree_unlock(mid);
1941 /* once for the path */
1942 free_extent_buffer(mid);
1944 root_sub_used(root, mid->len);
1945 btrfs_free_tree_block(trans, root, mid, 0, 1);
1946 /* once for the root ptr */
1947 free_extent_buffer_stale(mid);
1950 if (btrfs_header_nritems(mid) >
1951 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1954 left = read_node_slot(root, parent, pslot - 1);
1956 btrfs_tree_lock(left);
1957 btrfs_set_lock_blocking(left);
1958 wret = btrfs_cow_block(trans, root, left,
1959 parent, pslot - 1, &left);
1965 right = read_node_slot(root, parent, pslot + 1);
1967 btrfs_tree_lock(right);
1968 btrfs_set_lock_blocking(right);
1969 wret = btrfs_cow_block(trans, root, right,
1970 parent, pslot + 1, &right);
1977 /* first, try to make some room in the middle buffer */
1979 orig_slot += btrfs_header_nritems(left);
1980 wret = push_node_left(trans, root, left, mid, 1);
1986 * then try to empty the right most buffer into the middle
1989 wret = push_node_left(trans, root, mid, right, 1);
1990 if (wret < 0 && wret != -ENOSPC)
1992 if (btrfs_header_nritems(right) == 0) {
1993 clean_tree_block(trans, root, right);
1994 btrfs_tree_unlock(right);
1995 del_ptr(root, path, level + 1, pslot + 1);
1996 root_sub_used(root, right->len);
1997 btrfs_free_tree_block(trans, root, right, 0, 1);
1998 free_extent_buffer_stale(right);
2001 struct btrfs_disk_key right_key;
2002 btrfs_node_key(right, &right_key, 0);
2003 tree_mod_log_set_node_key(root->fs_info, parent,
2005 btrfs_set_node_key(parent, &right_key, pslot + 1);
2006 btrfs_mark_buffer_dirty(parent);
2009 if (btrfs_header_nritems(mid) == 1) {
2011 * we're not allowed to leave a node with one item in the
2012 * tree during a delete. A deletion from lower in the tree
2013 * could try to delete the only pointer in this node.
2014 * So, pull some keys from the left.
2015 * There has to be a left pointer at this point because
2016 * otherwise we would have pulled some pointers from the
2021 btrfs_std_error(root->fs_info, ret);
2024 wret = balance_node_right(trans, root, mid, left);
2030 wret = push_node_left(trans, root, left, mid, 1);
2036 if (btrfs_header_nritems(mid) == 0) {
2037 clean_tree_block(trans, root, mid);
2038 btrfs_tree_unlock(mid);
2039 del_ptr(root, path, level + 1, pslot);
2040 root_sub_used(root, mid->len);
2041 btrfs_free_tree_block(trans, root, mid, 0, 1);
2042 free_extent_buffer_stale(mid);
2045 /* update the parent key to reflect our changes */
2046 struct btrfs_disk_key mid_key;
2047 btrfs_node_key(mid, &mid_key, 0);
2048 tree_mod_log_set_node_key(root->fs_info, parent,
2050 btrfs_set_node_key(parent, &mid_key, pslot);
2051 btrfs_mark_buffer_dirty(parent);
2054 /* update the path */
2056 if (btrfs_header_nritems(left) > orig_slot) {
2057 extent_buffer_get(left);
2058 /* left was locked after cow */
2059 path->nodes[level] = left;
2060 path->slots[level + 1] -= 1;
2061 path->slots[level] = orig_slot;
2063 btrfs_tree_unlock(mid);
2064 free_extent_buffer(mid);
2067 orig_slot -= btrfs_header_nritems(left);
2068 path->slots[level] = orig_slot;
2071 /* double check we haven't messed things up */
2073 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
2077 btrfs_tree_unlock(right);
2078 free_extent_buffer(right);
2081 if (path->nodes[level] != left)
2082 btrfs_tree_unlock(left);
2083 free_extent_buffer(left);
2088 /* Node balancing for insertion. Here we only split or push nodes around
2089 * when they are completely full. This is also done top down, so we
2090 * have to be pessimistic.
2092 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
2093 struct btrfs_root *root,
2094 struct btrfs_path *path, int level)
2096 struct extent_buffer *right = NULL;
2097 struct extent_buffer *mid;
2098 struct extent_buffer *left = NULL;
2099 struct extent_buffer *parent = NULL;
2103 int orig_slot = path->slots[level];
2108 mid = path->nodes[level];
2109 WARN_ON(btrfs_header_generation(mid) != trans->transid);
2111 if (level < BTRFS_MAX_LEVEL - 1) {
2112 parent = path->nodes[level + 1];
2113 pslot = path->slots[level + 1];
2119 left = read_node_slot(root, parent, pslot - 1);
2121 /* first, try to make some room in the middle buffer */
2125 btrfs_tree_lock(left);
2126 btrfs_set_lock_blocking(left);
2128 left_nr = btrfs_header_nritems(left);
2129 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
2132 ret = btrfs_cow_block(trans, root, left, parent,
2137 wret = push_node_left(trans, root,
2144 struct btrfs_disk_key disk_key;
2145 orig_slot += left_nr;
2146 btrfs_node_key(mid, &disk_key, 0);
2147 tree_mod_log_set_node_key(root->fs_info, parent,
2149 btrfs_set_node_key(parent, &disk_key, pslot);
2150 btrfs_mark_buffer_dirty(parent);
2151 if (btrfs_header_nritems(left) > orig_slot) {
2152 path->nodes[level] = left;
2153 path->slots[level + 1] -= 1;
2154 path->slots[level] = orig_slot;
2155 btrfs_tree_unlock(mid);
2156 free_extent_buffer(mid);
2159 btrfs_header_nritems(left);
2160 path->slots[level] = orig_slot;
2161 btrfs_tree_unlock(left);
2162 free_extent_buffer(left);
2166 btrfs_tree_unlock(left);
2167 free_extent_buffer(left);
2169 right = read_node_slot(root, parent, pslot + 1);
2172 * then try to empty the right most buffer into the middle
2177 btrfs_tree_lock(right);
2178 btrfs_set_lock_blocking(right);
2180 right_nr = btrfs_header_nritems(right);
2181 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
2184 ret = btrfs_cow_block(trans, root, right,
2190 wret = balance_node_right(trans, root,
2197 struct btrfs_disk_key disk_key;
2199 btrfs_node_key(right, &disk_key, 0);
2200 tree_mod_log_set_node_key(root->fs_info, parent,
2202 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2203 btrfs_mark_buffer_dirty(parent);
2205 if (btrfs_header_nritems(mid) <= orig_slot) {
2206 path->nodes[level] = right;
2207 path->slots[level + 1] += 1;
2208 path->slots[level] = orig_slot -
2209 btrfs_header_nritems(mid);
2210 btrfs_tree_unlock(mid);
2211 free_extent_buffer(mid);
2213 btrfs_tree_unlock(right);
2214 free_extent_buffer(right);
2218 btrfs_tree_unlock(right);
2219 free_extent_buffer(right);
2225 * readahead one full node of leaves, finding things that are close
2226 * to the block in 'slot', and triggering ra on them.
2228 static void reada_for_search(struct btrfs_root *root,
2229 struct btrfs_path *path,
2230 int level, int slot, u64 objectid)
2232 struct extent_buffer *node;
2233 struct btrfs_disk_key disk_key;
2239 int direction = path->reada;
2240 struct extent_buffer *eb;
2248 if (!path->nodes[level])
2251 node = path->nodes[level];
2253 search = btrfs_node_blockptr(node, slot);
2254 blocksize = root->nodesize;
2255 eb = btrfs_find_tree_block(root, search);
2257 free_extent_buffer(eb);
2263 nritems = btrfs_header_nritems(node);
2267 if (direction < 0) {
2271 } else if (direction > 0) {
2276 if (path->reada < 0 && objectid) {
2277 btrfs_node_key(node, &disk_key, nr);
2278 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2281 search = btrfs_node_blockptr(node, nr);
2282 if ((search <= target && target - search <= 65536) ||
2283 (search > target && search - target <= 65536)) {
2284 gen = btrfs_node_ptr_generation(node, nr);
2285 readahead_tree_block(root, search, blocksize);
2289 if ((nread > 65536 || nscan > 32))
2294 static noinline void reada_for_balance(struct btrfs_root *root,
2295 struct btrfs_path *path, int level)
2299 struct extent_buffer *parent;
2300 struct extent_buffer *eb;
2306 parent = path->nodes[level + 1];
2310 nritems = btrfs_header_nritems(parent);
2311 slot = path->slots[level + 1];
2312 blocksize = root->nodesize;
2315 block1 = btrfs_node_blockptr(parent, slot - 1);
2316 gen = btrfs_node_ptr_generation(parent, slot - 1);
2317 eb = btrfs_find_tree_block(root, block1);
2319 * if we get -eagain from btrfs_buffer_uptodate, we
2320 * don't want to return eagain here. That will loop
2323 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2325 free_extent_buffer(eb);
2327 if (slot + 1 < nritems) {
2328 block2 = btrfs_node_blockptr(parent, slot + 1);
2329 gen = btrfs_node_ptr_generation(parent, slot + 1);
2330 eb = btrfs_find_tree_block(root, block2);
2331 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2333 free_extent_buffer(eb);
2337 readahead_tree_block(root, block1, blocksize);
2339 readahead_tree_block(root, block2, blocksize);
2344 * when we walk down the tree, it is usually safe to unlock the higher layers
2345 * in the tree. The exceptions are when our path goes through slot 0, because
2346 * operations on the tree might require changing key pointers higher up in the
2349 * callers might also have set path->keep_locks, which tells this code to keep
2350 * the lock if the path points to the last slot in the block. This is part of
2351 * walking through the tree, and selecting the next slot in the higher block.
2353 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2354 * if lowest_unlock is 1, level 0 won't be unlocked
2356 static noinline void unlock_up(struct btrfs_path *path, int level,
2357 int lowest_unlock, int min_write_lock_level,
2358 int *write_lock_level)
2361 int skip_level = level;
2363 struct extent_buffer *t;
2365 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2366 if (!path->nodes[i])
2368 if (!path->locks[i])
2370 if (!no_skips && path->slots[i] == 0) {
2374 if (!no_skips && path->keep_locks) {
2377 nritems = btrfs_header_nritems(t);
2378 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2383 if (skip_level < i && i >= lowest_unlock)
2387 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2388 btrfs_tree_unlock_rw(t, path->locks[i]);
2390 if (write_lock_level &&
2391 i > min_write_lock_level &&
2392 i <= *write_lock_level) {
2393 *write_lock_level = i - 1;
2400 * This releases any locks held in the path starting at level and
2401 * going all the way up to the root.
2403 * btrfs_search_slot will keep the lock held on higher nodes in a few
2404 * corner cases, such as COW of the block at slot zero in the node. This
2405 * ignores those rules, and it should only be called when there are no
2406 * more updates to be done higher up in the tree.
2408 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2412 if (path->keep_locks)
2415 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2416 if (!path->nodes[i])
2418 if (!path->locks[i])
2420 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2426 * helper function for btrfs_search_slot. The goal is to find a block
2427 * in cache without setting the path to blocking. If we find the block
2428 * we return zero and the path is unchanged.
2430 * If we can't find the block, we set the path blocking and do some
2431 * reada. -EAGAIN is returned and the search must be repeated.
2434 read_block_for_search(struct btrfs_trans_handle *trans,
2435 struct btrfs_root *root, struct btrfs_path *p,
2436 struct extent_buffer **eb_ret, int level, int slot,
2437 struct btrfs_key *key, u64 time_seq)
2441 struct extent_buffer *b = *eb_ret;
2442 struct extent_buffer *tmp;
2445 blocknr = btrfs_node_blockptr(b, slot);
2446 gen = btrfs_node_ptr_generation(b, slot);
2448 tmp = btrfs_find_tree_block(root, blocknr);
2450 /* first we do an atomic uptodate check */
2451 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2456 /* the pages were up to date, but we failed
2457 * the generation number check. Do a full
2458 * read for the generation number that is correct.
2459 * We must do this without dropping locks so
2460 * we can trust our generation number
2462 btrfs_set_path_blocking(p);
2464 /* now we're allowed to do a blocking uptodate check */
2465 ret = btrfs_read_buffer(tmp, gen);
2470 free_extent_buffer(tmp);
2471 btrfs_release_path(p);
2476 * reduce lock contention at high levels
2477 * of the btree by dropping locks before
2478 * we read. Don't release the lock on the current
2479 * level because we need to walk this node to figure
2480 * out which blocks to read.
2482 btrfs_unlock_up_safe(p, level + 1);
2483 btrfs_set_path_blocking(p);
2485 free_extent_buffer(tmp);
2487 reada_for_search(root, p, level, slot, key->objectid);
2489 btrfs_release_path(p);
2492 tmp = read_tree_block(root, blocknr, 0);
2495 * If the read above didn't mark this buffer up to date,
2496 * it will never end up being up to date. Set ret to EIO now
2497 * and give up so that our caller doesn't loop forever
2500 if (!btrfs_buffer_uptodate(tmp, 0, 0))
2502 free_extent_buffer(tmp);
2508 * helper function for btrfs_search_slot. This does all of the checks
2509 * for node-level blocks and does any balancing required based on
2512 * If no extra work was required, zero is returned. If we had to
2513 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2517 setup_nodes_for_search(struct btrfs_trans_handle *trans,
2518 struct btrfs_root *root, struct btrfs_path *p,
2519 struct extent_buffer *b, int level, int ins_len,
2520 int *write_lock_level)
2523 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2524 BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
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(root, p, level);
2535 sret = split_node(trans, root, p, level);
2536 btrfs_clear_path_blocking(p, NULL, 0);
2543 b = p->nodes[level];
2544 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2545 BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
2548 if (*write_lock_level < level + 1) {
2549 *write_lock_level = level + 1;
2550 btrfs_release_path(p);
2554 btrfs_set_path_blocking(p);
2555 reada_for_balance(root, p, level);
2556 sret = balance_level(trans, root, p, level);
2557 btrfs_clear_path_blocking(p, NULL, 0);
2563 b = p->nodes[level];
2565 btrfs_release_path(p);
2568 BUG_ON(btrfs_header_nritems(b) == 1);
2578 static void key_search_validate(struct extent_buffer *b,
2579 struct btrfs_key *key,
2582 #ifdef CONFIG_BTRFS_ASSERT
2583 struct btrfs_disk_key disk_key;
2585 btrfs_cpu_key_to_disk(&disk_key, key);
2588 ASSERT(!memcmp_extent_buffer(b, &disk_key,
2589 offsetof(struct btrfs_leaf, items[0].key),
2592 ASSERT(!memcmp_extent_buffer(b, &disk_key,
2593 offsetof(struct btrfs_node, ptrs[0].key),
2598 static int key_search(struct extent_buffer *b, struct btrfs_key *key,
2599 int level, int *prev_cmp, int *slot)
2601 if (*prev_cmp != 0) {
2602 *prev_cmp = bin_search(b, key, level, slot);
2606 key_search_validate(b, key, level);
2612 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
2613 u64 iobjectid, u64 ioff, u8 key_type,
2614 struct btrfs_key *found_key)
2617 struct btrfs_key key;
2618 struct extent_buffer *eb;
2622 key.type = key_type;
2623 key.objectid = iobjectid;
2626 ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
2627 if ((ret < 0) || (found_key == NULL))
2630 eb = path->nodes[0];
2631 if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {
2632 ret = btrfs_next_leaf(fs_root, path);
2635 eb = path->nodes[0];
2638 btrfs_item_key_to_cpu(eb, found_key, path->slots[0]);
2639 if (found_key->type != key.type ||
2640 found_key->objectid != key.objectid)
2647 * look for key in the tree. path is filled in with nodes along the way
2648 * if key is found, we return zero and you can find the item in the leaf
2649 * level of the path (level 0)
2651 * If the key isn't found, the path points to the slot where it should
2652 * be inserted, and 1 is returned. If there are other errors during the
2653 * search a negative error number is returned.
2655 * if ins_len > 0, nodes and leaves will be split as we walk down the
2656 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
2659 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
2660 *root, struct btrfs_key *key, struct btrfs_path *p, int
2663 struct extent_buffer *b;
2668 int lowest_unlock = 1;
2670 /* everything at write_lock_level or lower must be write locked */
2671 int write_lock_level = 0;
2672 u8 lowest_level = 0;
2673 int min_write_lock_level;
2676 lowest_level = p->lowest_level;
2677 WARN_ON(lowest_level && ins_len > 0);
2678 WARN_ON(p->nodes[0] != NULL);
2679 BUG_ON(!cow && ins_len);
2684 /* when we are removing items, we might have to go up to level
2685 * two as we update tree pointers Make sure we keep write
2686 * for those levels as well
2688 write_lock_level = 2;
2689 } else if (ins_len > 0) {
2691 * for inserting items, make sure we have a write lock on
2692 * level 1 so we can update keys
2694 write_lock_level = 1;
2698 write_lock_level = -1;
2700 if (cow && (p->keep_locks || p->lowest_level))
2701 write_lock_level = BTRFS_MAX_LEVEL;
2703 min_write_lock_level = write_lock_level;
2708 * we try very hard to do read locks on the root
2710 root_lock = BTRFS_READ_LOCK;
2712 if (p->search_commit_root) {
2714 * the commit roots are read only
2715 * so we always do read locks
2717 if (p->need_commit_sem)
2718 down_read(&root->fs_info->commit_root_sem);
2719 b = root->commit_root;
2720 extent_buffer_get(b);
2721 level = btrfs_header_level(b);
2722 if (p->need_commit_sem)
2723 up_read(&root->fs_info->commit_root_sem);
2724 if (!p->skip_locking)
2725 btrfs_tree_read_lock(b);
2727 if (p->skip_locking) {
2728 b = btrfs_root_node(root);
2729 level = btrfs_header_level(b);
2731 /* we don't know the level of the root node
2732 * until we actually have it read locked
2734 b = btrfs_read_lock_root_node(root);
2735 level = btrfs_header_level(b);
2736 if (level <= write_lock_level) {
2737 /* whoops, must trade for write lock */
2738 btrfs_tree_read_unlock(b);
2739 free_extent_buffer(b);
2740 b = btrfs_lock_root_node(root);
2741 root_lock = BTRFS_WRITE_LOCK;
2743 /* the level might have changed, check again */
2744 level = btrfs_header_level(b);
2748 p->nodes[level] = b;
2749 if (!p->skip_locking)
2750 p->locks[level] = root_lock;
2753 level = btrfs_header_level(b);
2756 * setup the path here so we can release it under lock
2757 * contention with the cow code
2761 * if we don't really need to cow this block
2762 * then we don't want to set the path blocking,
2763 * so we test it here
2765 if (!should_cow_block(trans, root, b))
2769 * must have write locks on this node and the
2772 if (level > write_lock_level ||
2773 (level + 1 > write_lock_level &&
2774 level + 1 < BTRFS_MAX_LEVEL &&
2775 p->nodes[level + 1])) {
2776 write_lock_level = level + 1;
2777 btrfs_release_path(p);
2781 btrfs_set_path_blocking(p);
2782 err = btrfs_cow_block(trans, root, b,
2783 p->nodes[level + 1],
2784 p->slots[level + 1], &b);
2791 p->nodes[level] = b;
2792 btrfs_clear_path_blocking(p, NULL, 0);
2795 * we have a lock on b and as long as we aren't changing
2796 * the tree, there is no way to for the items in b to change.
2797 * It is safe to drop the lock on our parent before we
2798 * go through the expensive btree search on b.
2800 * If we're inserting or deleting (ins_len != 0), then we might
2801 * be changing slot zero, which may require changing the parent.
2802 * So, we can't drop the lock until after we know which slot
2803 * we're operating on.
2805 if (!ins_len && !p->keep_locks) {
2808 if (u < BTRFS_MAX_LEVEL && p->locks[u]) {
2809 btrfs_tree_unlock_rw(p->nodes[u], p->locks[u]);
2814 ret = key_search(b, key, level, &prev_cmp, &slot);
2818 if (ret && slot > 0) {
2822 p->slots[level] = slot;
2823 err = setup_nodes_for_search(trans, root, p, b, level,
2824 ins_len, &write_lock_level);
2831 b = p->nodes[level];
2832 slot = p->slots[level];
2835 * slot 0 is special, if we change the key
2836 * we have to update the parent pointer
2837 * which means we must have a write lock
2840 if (slot == 0 && ins_len &&
2841 write_lock_level < level + 1) {
2842 write_lock_level = level + 1;
2843 btrfs_release_path(p);
2847 unlock_up(p, level, lowest_unlock,
2848 min_write_lock_level, &write_lock_level);
2850 if (level == lowest_level) {
2856 err = read_block_for_search(trans, root, p,
2857 &b, level, slot, key, 0);
2865 if (!p->skip_locking) {
2866 level = btrfs_header_level(b);
2867 if (level <= write_lock_level) {
2868 err = btrfs_try_tree_write_lock(b);
2870 btrfs_set_path_blocking(p);
2872 btrfs_clear_path_blocking(p, b,
2875 p->locks[level] = BTRFS_WRITE_LOCK;
2877 err = btrfs_tree_read_lock_atomic(b);
2879 btrfs_set_path_blocking(p);
2880 btrfs_tree_read_lock(b);
2881 btrfs_clear_path_blocking(p, b,
2884 p->locks[level] = BTRFS_READ_LOCK;
2886 p->nodes[level] = b;
2889 p->slots[level] = slot;
2891 btrfs_leaf_free_space(root, b) < ins_len) {
2892 if (write_lock_level < 1) {
2893 write_lock_level = 1;
2894 btrfs_release_path(p);
2898 btrfs_set_path_blocking(p);
2899 err = split_leaf(trans, root, key,
2900 p, ins_len, ret == 0);
2901 btrfs_clear_path_blocking(p, NULL, 0);
2909 if (!p->search_for_split)
2910 unlock_up(p, level, lowest_unlock,
2911 min_write_lock_level, &write_lock_level);
2918 * we don't really know what they plan on doing with the path
2919 * from here on, so for now just mark it as blocking
2921 if (!p->leave_spinning)
2922 btrfs_set_path_blocking(p);
2923 if (ret < 0 && !p->skip_release_on_error)
2924 btrfs_release_path(p);
2929 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2930 * current state of the tree together with the operations recorded in the tree
2931 * modification log to search for the key in a previous version of this tree, as
2932 * denoted by the time_seq parameter.
2934 * Naturally, there is no support for insert, delete or cow operations.
2936 * The resulting path and return value will be set up as if we called
2937 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2939 int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
2940 struct btrfs_path *p, u64 time_seq)
2942 struct extent_buffer *b;
2947 int lowest_unlock = 1;
2948 u8 lowest_level = 0;
2951 lowest_level = p->lowest_level;
2952 WARN_ON(p->nodes[0] != NULL);
2954 if (p->search_commit_root) {
2956 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2960 b = get_old_root(root, time_seq);
2961 level = btrfs_header_level(b);
2962 p->locks[level] = BTRFS_READ_LOCK;
2965 level = btrfs_header_level(b);
2966 p->nodes[level] = b;
2967 btrfs_clear_path_blocking(p, NULL, 0);
2970 * we have a lock on b and as long as we aren't changing
2971 * the tree, there is no way to for the items in b to change.
2972 * It is safe to drop the lock on our parent before we
2973 * go through the expensive btree search on b.
2975 btrfs_unlock_up_safe(p, level + 1);
2978 * Since we can unwind eb's we want to do a real search every
2982 ret = key_search(b, key, level, &prev_cmp, &slot);
2986 if (ret && slot > 0) {
2990 p->slots[level] = slot;
2991 unlock_up(p, level, lowest_unlock, 0, NULL);
2993 if (level == lowest_level) {
2999 err = read_block_for_search(NULL, root, p, &b, level,
3000 slot, key, time_seq);
3008 level = btrfs_header_level(b);
3009 err = btrfs_tree_read_lock_atomic(b);
3011 btrfs_set_path_blocking(p);
3012 btrfs_tree_read_lock(b);
3013 btrfs_clear_path_blocking(p, b,
3016 b = tree_mod_log_rewind(root->fs_info, p, b, time_seq);
3021 p->locks[level] = BTRFS_READ_LOCK;
3022 p->nodes[level] = b;
3024 p->slots[level] = slot;
3025 unlock_up(p, level, lowest_unlock, 0, NULL);
3031 if (!p->leave_spinning)
3032 btrfs_set_path_blocking(p);
3034 btrfs_release_path(p);
3040 * helper to use instead of search slot if no exact match is needed but
3041 * instead the next or previous item should be returned.
3042 * When find_higher is true, the next higher item is returned, the next lower
3044 * When return_any and find_higher are both true, and no higher item is found,
3045 * return the next lower instead.
3046 * When return_any is true and find_higher is false, and no lower item is found,
3047 * return the next higher instead.
3048 * It returns 0 if any item is found, 1 if none is found (tree empty), and
3051 int btrfs_search_slot_for_read(struct btrfs_root *root,
3052 struct btrfs_key *key, struct btrfs_path *p,
3053 int find_higher, int return_any)
3056 struct extent_buffer *leaf;
3059 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
3063 * a return value of 1 means the path is at the position where the
3064 * item should be inserted. Normally this is the next bigger item,
3065 * but in case the previous item is the last in a leaf, path points
3066 * to the first free slot in the previous leaf, i.e. at an invalid
3072 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
3073 ret = btrfs_next_leaf(root, p);
3079 * no higher item found, return the next
3084 btrfs_release_path(p);
3088 if (p->slots[0] == 0) {
3089 ret = btrfs_prev_leaf(root, p);
3094 if (p->slots[0] == btrfs_header_nritems(leaf))
3101 * no lower item found, return the next
3106 btrfs_release_path(p);
3116 * adjust the pointers going up the tree, starting at level
3117 * making sure the right key of each node is points to 'key'.
3118 * This is used after shifting pointers to the left, so it stops
3119 * fixing up pointers when a given leaf/node is not in slot 0 of the
3123 static void fixup_low_keys(struct btrfs_root *root, struct btrfs_path *path,
3124 struct btrfs_disk_key *key, int level)
3127 struct extent_buffer *t;
3129 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
3130 int tslot = path->slots[i];
3131 if (!path->nodes[i])
3134 tree_mod_log_set_node_key(root->fs_info, t, tslot, 1);
3135 btrfs_set_node_key(t, key, tslot);
3136 btrfs_mark_buffer_dirty(path->nodes[i]);
3145 * This function isn't completely safe. It's the caller's responsibility
3146 * that the new key won't break the order
3148 void btrfs_set_item_key_safe(struct btrfs_root *root, struct btrfs_path *path,
3149 struct btrfs_key *new_key)
3151 struct btrfs_disk_key disk_key;
3152 struct extent_buffer *eb;
3155 eb = path->nodes[0];
3156 slot = path->slots[0];
3158 btrfs_item_key(eb, &disk_key, slot - 1);
3159 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
3161 if (slot < btrfs_header_nritems(eb) - 1) {
3162 btrfs_item_key(eb, &disk_key, slot + 1);
3163 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
3166 btrfs_cpu_key_to_disk(&disk_key, new_key);
3167 btrfs_set_item_key(eb, &disk_key, slot);
3168 btrfs_mark_buffer_dirty(eb);
3170 fixup_low_keys(root, path, &disk_key, 1);
3174 * try to push data from one node into the next node left in the
3177 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
3178 * error, and > 0 if there was no room in the left hand block.
3180 static int push_node_left(struct btrfs_trans_handle *trans,
3181 struct btrfs_root *root, struct extent_buffer *dst,
3182 struct extent_buffer *src, int empty)
3189 src_nritems = btrfs_header_nritems(src);
3190 dst_nritems = btrfs_header_nritems(dst);
3191 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
3192 WARN_ON(btrfs_header_generation(src) != trans->transid);
3193 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3195 if (!empty && src_nritems <= 8)
3198 if (push_items <= 0)
3202 push_items = min(src_nritems, push_items);
3203 if (push_items < src_nritems) {
3204 /* leave at least 8 pointers in the node if
3205 * we aren't going to empty it
3207 if (src_nritems - push_items < 8) {
3208 if (push_items <= 8)
3214 push_items = min(src_nritems - 8, push_items);
3216 ret = tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
3219 btrfs_abort_transaction(trans, root, ret);
3222 copy_extent_buffer(dst, src,
3223 btrfs_node_key_ptr_offset(dst_nritems),
3224 btrfs_node_key_ptr_offset(0),
3225 push_items * sizeof(struct btrfs_key_ptr));
3227 if (push_items < src_nritems) {
3229 * don't call tree_mod_log_eb_move here, key removal was already
3230 * fully logged by tree_mod_log_eb_copy above.
3232 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3233 btrfs_node_key_ptr_offset(push_items),
3234 (src_nritems - push_items) *
3235 sizeof(struct btrfs_key_ptr));
3237 btrfs_set_header_nritems(src, src_nritems - push_items);
3238 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3239 btrfs_mark_buffer_dirty(src);
3240 btrfs_mark_buffer_dirty(dst);
3246 * try to push data from one node into the next node right in the
3249 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3250 * error, and > 0 if there was no room in the right hand block.
3252 * this will only push up to 1/2 the contents of the left node over
3254 static int balance_node_right(struct btrfs_trans_handle *trans,
3255 struct btrfs_root *root,
3256 struct extent_buffer *dst,
3257 struct extent_buffer *src)
3265 WARN_ON(btrfs_header_generation(src) != trans->transid);
3266 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3268 src_nritems = btrfs_header_nritems(src);
3269 dst_nritems = btrfs_header_nritems(dst);
3270 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
3271 if (push_items <= 0)
3274 if (src_nritems < 4)
3277 max_push = src_nritems / 2 + 1;
3278 /* don't try to empty the node */
3279 if (max_push >= src_nritems)
3282 if (max_push < push_items)
3283 push_items = max_push;
3285 tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
3286 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3287 btrfs_node_key_ptr_offset(0),
3289 sizeof(struct btrfs_key_ptr));
3291 ret = tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
3292 src_nritems - push_items, push_items);
3294 btrfs_abort_transaction(trans, root, ret);
3297 copy_extent_buffer(dst, src,
3298 btrfs_node_key_ptr_offset(0),
3299 btrfs_node_key_ptr_offset(src_nritems - push_items),
3300 push_items * sizeof(struct btrfs_key_ptr));
3302 btrfs_set_header_nritems(src, src_nritems - push_items);
3303 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3305 btrfs_mark_buffer_dirty(src);
3306 btrfs_mark_buffer_dirty(dst);
3312 * helper function to insert a new root level in the tree.
3313 * A new node is allocated, and a single item is inserted to
3314 * point to the existing root
3316 * returns zero on success or < 0 on failure.
3318 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3319 struct btrfs_root *root,
3320 struct btrfs_path *path, int level)
3323 struct extent_buffer *lower;
3324 struct extent_buffer *c;
3325 struct extent_buffer *old;
3326 struct btrfs_disk_key lower_key;
3328 BUG_ON(path->nodes[level]);
3329 BUG_ON(path->nodes[level-1] != root->node);
3331 lower = path->nodes[level-1];
3333 btrfs_item_key(lower, &lower_key, 0);
3335 btrfs_node_key(lower, &lower_key, 0);
3337 c = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3338 &lower_key, level, root->node->start, 0);
3342 root_add_used(root, root->nodesize);
3344 memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
3345 btrfs_set_header_nritems(c, 1);
3346 btrfs_set_header_level(c, level);
3347 btrfs_set_header_bytenr(c, c->start);
3348 btrfs_set_header_generation(c, trans->transid);
3349 btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
3350 btrfs_set_header_owner(c, root->root_key.objectid);
3352 write_extent_buffer(c, root->fs_info->fsid, btrfs_header_fsid(),
3355 write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
3356 btrfs_header_chunk_tree_uuid(c), BTRFS_UUID_SIZE);
3358 btrfs_set_node_key(c, &lower_key, 0);
3359 btrfs_set_node_blockptr(c, 0, lower->start);
3360 lower_gen = btrfs_header_generation(lower);
3361 WARN_ON(lower_gen != trans->transid);
3363 btrfs_set_node_ptr_generation(c, 0, lower_gen);
3365 btrfs_mark_buffer_dirty(c);
3368 tree_mod_log_set_root_pointer(root, c, 0);
3369 rcu_assign_pointer(root->node, c);
3371 /* the super has an extra ref to root->node */
3372 free_extent_buffer(old);
3374 add_root_to_dirty_list(root);
3375 extent_buffer_get(c);
3376 path->nodes[level] = c;
3377 path->locks[level] = BTRFS_WRITE_LOCK;
3378 path->slots[level] = 0;
3383 * worker function to insert a single pointer in a node.
3384 * the node should have enough room for the pointer already
3386 * slot and level indicate where you want the key to go, and
3387 * blocknr is the block the key points to.
3389 static void insert_ptr(struct btrfs_trans_handle *trans,
3390 struct btrfs_root *root, struct btrfs_path *path,
3391 struct btrfs_disk_key *key, u64 bytenr,
3392 int slot, int level)
3394 struct extent_buffer *lower;
3398 BUG_ON(!path->nodes[level]);
3399 btrfs_assert_tree_locked(path->nodes[level]);
3400 lower = path->nodes[level];
3401 nritems = btrfs_header_nritems(lower);
3402 BUG_ON(slot > nritems);
3403 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
3404 if (slot != nritems) {
3406 tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
3407 slot, nritems - slot);
3408 memmove_extent_buffer(lower,
3409 btrfs_node_key_ptr_offset(slot + 1),
3410 btrfs_node_key_ptr_offset(slot),
3411 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3414 ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
3415 MOD_LOG_KEY_ADD, GFP_NOFS);
3418 btrfs_set_node_key(lower, key, slot);
3419 btrfs_set_node_blockptr(lower, slot, bytenr);
3420 WARN_ON(trans->transid == 0);
3421 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3422 btrfs_set_header_nritems(lower, nritems + 1);
3423 btrfs_mark_buffer_dirty(lower);
3427 * split the node at the specified level in path in two.
3428 * The path is corrected to point to the appropriate node after the split
3430 * Before splitting this tries to make some room in the node by pushing
3431 * left and right, if either one works, it returns right away.
3433 * returns 0 on success and < 0 on failure
3435 static noinline int split_node(struct btrfs_trans_handle *trans,
3436 struct btrfs_root *root,
3437 struct btrfs_path *path, int level)
3439 struct extent_buffer *c;
3440 struct extent_buffer *split;
3441 struct btrfs_disk_key disk_key;
3446 c = path->nodes[level];
3447 WARN_ON(btrfs_header_generation(c) != trans->transid);
3448 if (c == root->node) {
3450 * trying to split the root, lets make a new one
3452 * tree mod log: We don't log_removal old root in
3453 * insert_new_root, because that root buffer will be kept as a
3454 * normal node. We are going to log removal of half of the
3455 * elements below with tree_mod_log_eb_copy. We're holding a
3456 * tree lock on the buffer, which is why we cannot race with
3457 * other tree_mod_log users.
3459 ret = insert_new_root(trans, root, path, level + 1);
3463 ret = push_nodes_for_insert(trans, root, path, level);
3464 c = path->nodes[level];
3465 if (!ret && btrfs_header_nritems(c) <
3466 BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
3472 c_nritems = btrfs_header_nritems(c);
3473 mid = (c_nritems + 1) / 2;
3474 btrfs_node_key(c, &disk_key, mid);
3476 split = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
3477 &disk_key, level, c->start, 0);
3479 return PTR_ERR(split);
3481 root_add_used(root, root->nodesize);
3483 memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
3484 btrfs_set_header_level(split, btrfs_header_level(c));
3485 btrfs_set_header_bytenr(split, split->start);
3486 btrfs_set_header_generation(split, trans->transid);
3487 btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3488 btrfs_set_header_owner(split, root->root_key.objectid);
3489 write_extent_buffer(split, root->fs_info->fsid,
3490 btrfs_header_fsid(), BTRFS_FSID_SIZE);
3491 write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
3492 btrfs_header_chunk_tree_uuid(split),
3495 ret = tree_mod_log_eb_copy(root->fs_info, split, c, 0,
3496 mid, c_nritems - mid);
3498 btrfs_abort_transaction(trans, root, ret);
3501 copy_extent_buffer(split, c,
3502 btrfs_node_key_ptr_offset(0),
3503 btrfs_node_key_ptr_offset(mid),
3504 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3505 btrfs_set_header_nritems(split, c_nritems - mid);
3506 btrfs_set_header_nritems(c, mid);
3509 btrfs_mark_buffer_dirty(c);
3510 btrfs_mark_buffer_dirty(split);
3512 insert_ptr(trans, root, path, &disk_key, split->start,
3513 path->slots[level + 1] + 1, level + 1);
3515 if (path->slots[level] >= mid) {
3516 path->slots[level] -= mid;
3517 btrfs_tree_unlock(c);
3518 free_extent_buffer(c);
3519 path->nodes[level] = split;
3520 path->slots[level + 1] += 1;
3522 btrfs_tree_unlock(split);
3523 free_extent_buffer(split);
3529 * how many bytes are required to store the items in a leaf. start
3530 * and nr indicate which items in the leaf to check. This totals up the
3531 * space used both by the item structs and the item data
3533 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3535 struct btrfs_item *start_item;
3536 struct btrfs_item *end_item;
3537 struct btrfs_map_token token;
3539 int nritems = btrfs_header_nritems(l);
3540 int end = min(nritems, start + nr) - 1;
3544 btrfs_init_map_token(&token);
3545 start_item = btrfs_item_nr(start);
3546 end_item = btrfs_item_nr(end);
3547 data_len = btrfs_token_item_offset(l, start_item, &token) +
3548 btrfs_token_item_size(l, start_item, &token);
3549 data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3550 data_len += sizeof(struct btrfs_item) * nr;
3551 WARN_ON(data_len < 0);
3556 * The space between the end of the leaf items and
3557 * the start of the leaf data. IOW, how much room
3558 * the leaf has left for both items and data
3560 noinline int btrfs_leaf_free_space(struct btrfs_root *root,
3561 struct extent_buffer *leaf)
3563 int nritems = btrfs_header_nritems(leaf);
3565 ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
3567 btrfs_crit(root->fs_info,
3568 "leaf free space ret %d, leaf data size %lu, used %d nritems %d",
3569 ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
3570 leaf_space_used(leaf, 0, nritems), nritems);
3576 * min slot controls the lowest index we're willing to push to the
3577 * right. We'll push up to and including min_slot, but no lower
3579 static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3580 struct btrfs_root *root,
3581 struct btrfs_path *path,
3582 int data_size, int empty,
3583 struct extent_buffer *right,
3584 int free_space, u32 left_nritems,
3587 struct extent_buffer *left = path->nodes[0];
3588 struct extent_buffer *upper = path->nodes[1];
3589 struct btrfs_map_token token;
3590 struct btrfs_disk_key disk_key;
3595 struct btrfs_item *item;
3601 btrfs_init_map_token(&token);
3606 nr = max_t(u32, 1, min_slot);
3608 if (path->slots[0] >= left_nritems)
3609 push_space += data_size;
3611 slot = path->slots[1];
3612 i = left_nritems - 1;
3614 item = btrfs_item_nr(i);
3616 if (!empty && push_items > 0) {
3617 if (path->slots[0] > i)
3619 if (path->slots[0] == i) {
3620 int space = btrfs_leaf_free_space(root, left);
3621 if (space + push_space * 2 > free_space)
3626 if (path->slots[0] == i)
3627 push_space += data_size;
3629 this_item_size = btrfs_item_size(left, item);
3630 if (this_item_size + sizeof(*item) + push_space > free_space)
3634 push_space += this_item_size + sizeof(*item);
3640 if (push_items == 0)
3643 WARN_ON(!empty && push_items == left_nritems);
3645 /* push left to right */
3646 right_nritems = btrfs_header_nritems(right);
3648 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3649 push_space -= leaf_data_end(root, left);
3651 /* make room in the right data area */
3652 data_end = leaf_data_end(root, right);
3653 memmove_extent_buffer(right,
3654 btrfs_leaf_data(right) + data_end - push_space,
3655 btrfs_leaf_data(right) + data_end,
3656 BTRFS_LEAF_DATA_SIZE(root) - data_end);
3658 /* copy from the left data area */
3659 copy_extent_buffer(right, left, btrfs_leaf_data(right) +
3660 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3661 btrfs_leaf_data(left) + leaf_data_end(root, left),
3664 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3665 btrfs_item_nr_offset(0),
3666 right_nritems * sizeof(struct btrfs_item));
3668 /* copy the items from left to right */
3669 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3670 btrfs_item_nr_offset(left_nritems - push_items),
3671 push_items * sizeof(struct btrfs_item));
3673 /* update the item pointers */
3674 right_nritems += push_items;
3675 btrfs_set_header_nritems(right, right_nritems);
3676 push_space = BTRFS_LEAF_DATA_SIZE(root);
3677 for (i = 0; i < right_nritems; i++) {
3678 item = btrfs_item_nr(i);
3679 push_space -= btrfs_token_item_size(right, item, &token);
3680 btrfs_set_token_item_offset(right, item, push_space, &token);
3683 left_nritems -= push_items;
3684 btrfs_set_header_nritems(left, left_nritems);
3687 btrfs_mark_buffer_dirty(left);
3689 clean_tree_block(trans, root, left);
3691 btrfs_mark_buffer_dirty(right);
3693 btrfs_item_key(right, &disk_key, 0);
3694 btrfs_set_node_key(upper, &disk_key, slot + 1);
3695 btrfs_mark_buffer_dirty(upper);
3697 /* then fixup the leaf pointer in the path */
3698 if (path->slots[0] >= left_nritems) {
3699 path->slots[0] -= left_nritems;
3700 if (btrfs_header_nritems(path->nodes[0]) == 0)
3701 clean_tree_block(trans, root, path->nodes[0]);
3702 btrfs_tree_unlock(path->nodes[0]);
3703 free_extent_buffer(path->nodes[0]);
3704 path->nodes[0] = right;
3705 path->slots[1] += 1;
3707 btrfs_tree_unlock(right);
3708 free_extent_buffer(right);
3713 btrfs_tree_unlock(right);
3714 free_extent_buffer(right);
3719 * push some data in the path leaf to the right, trying to free up at
3720 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3722 * returns 1 if the push failed because the other node didn't have enough
3723 * room, 0 if everything worked out and < 0 if there were major errors.
3725 * this will push starting from min_slot to the end of the leaf. It won't
3726 * push any slot lower than min_slot
3728 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3729 *root, struct btrfs_path *path,
3730 int min_data_size, int data_size,
3731 int empty, u32 min_slot)
3733 struct extent_buffer *left = path->nodes[0];
3734 struct extent_buffer *right;
3735 struct extent_buffer *upper;
3741 if (!path->nodes[1])
3744 slot = path->slots[1];
3745 upper = path->nodes[1];
3746 if (slot >= btrfs_header_nritems(upper) - 1)
3749 btrfs_assert_tree_locked(path->nodes[1]);
3751 right = read_node_slot(root, upper, slot + 1);
3755 btrfs_tree_lock(right);
3756 btrfs_set_lock_blocking(right);
3758 free_space = btrfs_leaf_free_space(root, right);
3759 if (free_space < data_size)
3762 /* cow and double check */
3763 ret = btrfs_cow_block(trans, root, right, upper,
3768 free_space = btrfs_leaf_free_space(root, right);
3769 if (free_space < data_size)
3772 left_nritems = btrfs_header_nritems(left);
3773 if (left_nritems == 0)
3776 if (path->slots[0] == left_nritems && !empty) {
3777 /* Key greater than all keys in the leaf, right neighbor has
3778 * enough room for it and we're not emptying our leaf to delete
3779 * it, therefore use right neighbor to insert the new item and
3780 * no need to touch/dirty our left leaft. */
3781 btrfs_tree_unlock(left);
3782 free_extent_buffer(left);
3783 path->nodes[0] = right;
3789 return __push_leaf_right(trans, root, path, min_data_size, empty,
3790 right, free_space, left_nritems, min_slot);
3792 btrfs_tree_unlock(right);
3793 free_extent_buffer(right);
3798 * push some data in the path leaf to the left, trying to free up at
3799 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3801 * max_slot can put a limit on how far into the leaf we'll push items. The
3802 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3805 static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3806 struct btrfs_root *root,
3807 struct btrfs_path *path, int data_size,
3808 int empty, struct extent_buffer *left,
3809 int free_space, u32 right_nritems,
3812 struct btrfs_disk_key disk_key;
3813 struct extent_buffer *right = path->nodes[0];
3817 struct btrfs_item *item;
3818 u32 old_left_nritems;
3822 u32 old_left_item_size;
3823 struct btrfs_map_token token;
3825 btrfs_init_map_token(&token);
3828 nr = min(right_nritems, max_slot);
3830 nr = min(right_nritems - 1, max_slot);
3832 for (i = 0; i < nr; i++) {
3833 item = btrfs_item_nr(i);
3835 if (!empty && push_items > 0) {
3836 if (path->slots[0] < i)
3838 if (path->slots[0] == i) {
3839 int space = btrfs_leaf_free_space(root, right);
3840 if (space + push_space * 2 > free_space)
3845 if (path->slots[0] == i)
3846 push_space += data_size;
3848 this_item_size = btrfs_item_size(right, item);
3849 if (this_item_size + sizeof(*item) + push_space > free_space)
3853 push_space += this_item_size + sizeof(*item);
3856 if (push_items == 0) {
3860 WARN_ON(!empty && push_items == btrfs_header_nritems(right));
3862 /* push data from right to left */
3863 copy_extent_buffer(left, right,
3864 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3865 btrfs_item_nr_offset(0),
3866 push_items * sizeof(struct btrfs_item));
3868 push_space = BTRFS_LEAF_DATA_SIZE(root) -
3869 btrfs_item_offset_nr(right, push_items - 1);
3871 copy_extent_buffer(left, right, btrfs_leaf_data(left) +
3872 leaf_data_end(root, left) - push_space,
3873 btrfs_leaf_data(right) +
3874 btrfs_item_offset_nr(right, push_items - 1),
3876 old_left_nritems = btrfs_header_nritems(left);
3877 BUG_ON(old_left_nritems <= 0);
3879 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3880 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3883 item = btrfs_item_nr(i);
3885 ioff = btrfs_token_item_offset(left, item, &token);
3886 btrfs_set_token_item_offset(left, item,
3887 ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
3890 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3892 /* fixup right node */
3893 if (push_items > right_nritems)
3894 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3897 if (push_items < right_nritems) {
3898 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3899 leaf_data_end(root, right);
3900 memmove_extent_buffer(right, btrfs_leaf_data(right) +
3901 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3902 btrfs_leaf_data(right) +
3903 leaf_data_end(root, right), push_space);
3905 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3906 btrfs_item_nr_offset(push_items),
3907 (btrfs_header_nritems(right) - push_items) *
3908 sizeof(struct btrfs_item));
3910 right_nritems -= push_items;
3911 btrfs_set_header_nritems(right, right_nritems);
3912 push_space = BTRFS_LEAF_DATA_SIZE(root);
3913 for (i = 0; i < right_nritems; i++) {
3914 item = btrfs_item_nr(i);
3916 push_space = push_space - btrfs_token_item_size(right,
3918 btrfs_set_token_item_offset(right, item, push_space, &token);
3921 btrfs_mark_buffer_dirty(left);
3923 btrfs_mark_buffer_dirty(right);
3925 clean_tree_block(trans, root, right);
3927 btrfs_item_key(right, &disk_key, 0);
3928 fixup_low_keys(root, path, &disk_key, 1);
3930 /* then fixup the leaf pointer in the path */
3931 if (path->slots[0] < push_items) {
3932 path->slots[0] += old_left_nritems;
3933 btrfs_tree_unlock(path->nodes[0]);
3934 free_extent_buffer(path->nodes[0]);
3935 path->nodes[0] = left;
3936 path->slots[1] -= 1;
3938 btrfs_tree_unlock(left);
3939 free_extent_buffer(left);
3940 path->slots[0] -= push_items;
3942 BUG_ON(path->slots[0] < 0);
3945 btrfs_tree_unlock(left);
3946 free_extent_buffer(left);
3951 * push some data in the path leaf to the left, trying to free up at
3952 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3954 * max_slot can put a limit on how far into the leaf we'll push items. The
3955 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3958 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3959 *root, struct btrfs_path *path, int min_data_size,
3960 int data_size, int empty, u32 max_slot)
3962 struct extent_buffer *right = path->nodes[0];
3963 struct extent_buffer *left;
3969 slot = path->slots[1];
3972 if (!path->nodes[1])
3975 right_nritems = btrfs_header_nritems(right);
3976 if (right_nritems == 0)
3979 btrfs_assert_tree_locked(path->nodes[1]);
3981 left = read_node_slot(root, path->nodes[1], slot - 1);
3985 btrfs_tree_lock(left);
3986 btrfs_set_lock_blocking(left);
3988 free_space = btrfs_leaf_free_space(root, left);
3989 if (free_space < data_size) {
3994 /* cow and double check */
3995 ret = btrfs_cow_block(trans, root, left,
3996 path->nodes[1], slot - 1, &left);
3998 /* we hit -ENOSPC, but it isn't fatal here */
4004 free_space = btrfs_leaf_free_space(root, left);
4005 if (free_space < data_size) {
4010 return __push_leaf_left(trans, root, path, min_data_size,
4011 empty, left, free_space, right_nritems,
4014 btrfs_tree_unlock(left);
4015 free_extent_buffer(left);
4020 * split the path's leaf in two, making sure there is at least data_size
4021 * available for the resulting leaf level of the path.
4023 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
4024 struct btrfs_root *root,
4025 struct btrfs_path *path,
4026 struct extent_buffer *l,
4027 struct extent_buffer *right,
4028 int slot, int mid, int nritems)
4033 struct btrfs_disk_key disk_key;
4034 struct btrfs_map_token token;
4036 btrfs_init_map_token(&token);
4038 nritems = nritems - mid;
4039 btrfs_set_header_nritems(right, nritems);
4040 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
4042 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
4043 btrfs_item_nr_offset(mid),
4044 nritems * sizeof(struct btrfs_item));
4046 copy_extent_buffer(right, l,
4047 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
4048 data_copy_size, btrfs_leaf_data(l) +
4049 leaf_data_end(root, l), data_copy_size);
4051 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
4052 btrfs_item_end_nr(l, mid);
4054 for (i = 0; i < nritems; i++) {
4055 struct btrfs_item *item = btrfs_item_nr(i);
4058 ioff = btrfs_token_item_offset(right, item, &token);
4059 btrfs_set_token_item_offset(right, item,
4060 ioff + rt_data_off, &token);
4063 btrfs_set_header_nritems(l, mid);
4064 btrfs_item_key(right, &disk_key, 0);
4065 insert_ptr(trans, root, path, &disk_key, right->start,
4066 path->slots[1] + 1, 1);
4068 btrfs_mark_buffer_dirty(right);
4069 btrfs_mark_buffer_dirty(l);
4070 BUG_ON(path->slots[0] != slot);
4073 btrfs_tree_unlock(path->nodes[0]);
4074 free_extent_buffer(path->nodes[0]);
4075 path->nodes[0] = right;
4076 path->slots[0] -= mid;
4077 path->slots[1] += 1;
4079 btrfs_tree_unlock(right);
4080 free_extent_buffer(right);
4083 BUG_ON(path->slots[0] < 0);
4087 * double splits happen when we need to insert a big item in the middle
4088 * of a leaf. A double split can leave us with 3 mostly empty leaves:
4089 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
4092 * We avoid this by trying to push the items on either side of our target
4093 * into the adjacent leaves. If all goes well we can avoid the double split
4096 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
4097 struct btrfs_root *root,
4098 struct btrfs_path *path,
4105 int space_needed = data_size;
4107 slot = path->slots[0];
4108 if (slot < btrfs_header_nritems(path->nodes[0]))
4109 space_needed -= btrfs_leaf_free_space(root, path->nodes[0]);
4112 * try to push all the items after our slot into the
4115 ret = push_leaf_right(trans, root, path, 1, space_needed, 0, slot);
4122 nritems = btrfs_header_nritems(path->nodes[0]);
4124 * our goal is to get our slot at the start or end of a leaf. If
4125 * we've done so we're done
4127 if (path->slots[0] == 0 || path->slots[0] == nritems)
4130 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
4133 /* try to push all the items before our slot into the next leaf */
4134 slot = path->slots[0];
4135 ret = push_leaf_left(trans, root, path, 1, space_needed, 0, slot);
4148 * split the path's leaf in two, making sure there is at least data_size
4149 * available for the resulting leaf level of the path.
4151 * returns 0 if all went well and < 0 on failure.
4153 static noinline int split_leaf(struct btrfs_trans_handle *trans,
4154 struct btrfs_root *root,
4155 struct btrfs_key *ins_key,
4156 struct btrfs_path *path, int data_size,
4159 struct btrfs_disk_key disk_key;
4160 struct extent_buffer *l;
4164 struct extent_buffer *right;
4168 int num_doubles = 0;
4169 int tried_avoid_double = 0;
4172 slot = path->slots[0];
4173 if (extend && data_size + btrfs_item_size_nr(l, slot) +
4174 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
4177 /* first try to make some room by pushing left and right */
4178 if (data_size && path->nodes[1]) {
4179 int space_needed = data_size;
4181 if (slot < btrfs_header_nritems(l))
4182 space_needed -= btrfs_leaf_free_space(root, l);
4184 wret = push_leaf_right(trans, root, path, space_needed,
4185 space_needed, 0, 0);
4189 wret = push_leaf_left(trans, root, path, space_needed,
4190 space_needed, 0, (u32)-1);
4196 /* did the pushes work? */
4197 if (btrfs_leaf_free_space(root, l) >= data_size)
4201 if (!path->nodes[1]) {
4202 ret = insert_new_root(trans, root, path, 1);
4209 slot = path->slots[0];
4210 nritems = btrfs_header_nritems(l);
4211 mid = (nritems + 1) / 2;
4215 leaf_space_used(l, mid, nritems - mid) + data_size >
4216 BTRFS_LEAF_DATA_SIZE(root)) {
4217 if (slot >= nritems) {
4221 if (mid != nritems &&
4222 leaf_space_used(l, mid, nritems - mid) +
4223 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
4224 if (data_size && !tried_avoid_double)
4225 goto push_for_double;
4231 if (leaf_space_used(l, 0, mid) + data_size >
4232 BTRFS_LEAF_DATA_SIZE(root)) {
4233 if (!extend && data_size && slot == 0) {
4235 } else if ((extend || !data_size) && slot == 0) {
4239 if (mid != nritems &&
4240 leaf_space_used(l, mid, nritems - mid) +
4241 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
4242 if (data_size && !tried_avoid_double)
4243 goto push_for_double;
4251 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4253 btrfs_item_key(l, &disk_key, mid);
4255 right = btrfs_alloc_tree_block(trans, root, 0, root->root_key.objectid,
4256 &disk_key, 0, l->start, 0);
4258 return PTR_ERR(right);
4260 root_add_used(root, root->nodesize);
4262 memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
4263 btrfs_set_header_bytenr(right, right->start);
4264 btrfs_set_header_generation(right, trans->transid);
4265 btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
4266 btrfs_set_header_owner(right, root->root_key.objectid);
4267 btrfs_set_header_level(right, 0);
4268 write_extent_buffer(right, root->fs_info->fsid,
4269 btrfs_header_fsid(), BTRFS_FSID_SIZE);
4271 write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
4272 btrfs_header_chunk_tree_uuid(right),
4277 btrfs_set_header_nritems(right, 0);
4278 insert_ptr(trans, root, path, &disk_key, right->start,
4279 path->slots[1] + 1, 1);
4280 btrfs_tree_unlock(path->nodes[0]);
4281 free_extent_buffer(path->nodes[0]);
4282 path->nodes[0] = right;
4284 path->slots[1] += 1;
4286 btrfs_set_header_nritems(right, 0);
4287 insert_ptr(trans, root, path, &disk_key, right->start,
4289 btrfs_tree_unlock(path->nodes[0]);
4290 free_extent_buffer(path->nodes[0]);
4291 path->nodes[0] = right;
4293 if (path->slots[1] == 0)
4294 fixup_low_keys(root, path, &disk_key, 1);
4296 btrfs_mark_buffer_dirty(right);
4300 copy_for_split(trans, root, path, l, right, slot, mid, nritems);
4303 BUG_ON(num_doubles != 0);
4311 push_for_double_split(trans, root, path, data_size);
4312 tried_avoid_double = 1;
4313 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
4318 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4319 struct btrfs_root *root,
4320 struct btrfs_path *path, int ins_len)
4322 struct btrfs_key key;
4323 struct extent_buffer *leaf;
4324 struct btrfs_file_extent_item *fi;
4329 leaf = path->nodes[0];
4330 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4332 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4333 key.type != BTRFS_EXTENT_CSUM_KEY);
4335 if (btrfs_leaf_free_space(root, leaf) >= ins_len)
4338 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4339 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4340 fi = btrfs_item_ptr(leaf, path->slots[0],
4341 struct btrfs_file_extent_item);
4342 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4344 btrfs_release_path(path);
4346 path->keep_locks = 1;
4347 path->search_for_split = 1;
4348 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4349 path->search_for_split = 0;
4354 leaf = path->nodes[0];
4355 /* if our item isn't there or got smaller, return now */
4356 if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4359 /* the leaf has changed, it now has room. return now */
4360 if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
4363 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4364 fi = btrfs_item_ptr(leaf, path->slots[0],
4365 struct btrfs_file_extent_item);
4366 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4370 btrfs_set_path_blocking(path);
4371 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4375 path->keep_locks = 0;
4376 btrfs_unlock_up_safe(path, 1);
4379 path->keep_locks = 0;
4383 static noinline int split_item(struct btrfs_trans_handle *trans,
4384 struct btrfs_root *root,
4385 struct btrfs_path *path,
4386 struct btrfs_key *new_key,
4387 unsigned long split_offset)
4389 struct extent_buffer *leaf;
4390 struct btrfs_item *item;
4391 struct btrfs_item *new_item;
4397 struct btrfs_disk_key disk_key;
4399 leaf = path->nodes[0];
4400 BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
4402 btrfs_set_path_blocking(path);
4404 item = btrfs_item_nr(path->slots[0]);
4405 orig_offset = btrfs_item_offset(leaf, item);
4406 item_size = btrfs_item_size(leaf, item);
4408 buf = kmalloc(item_size, GFP_NOFS);
4412 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4413 path->slots[0]), item_size);
4415 slot = path->slots[0] + 1;
4416 nritems = btrfs_header_nritems(leaf);
4417 if (slot != nritems) {
4418 /* shift the items */
4419 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4420 btrfs_item_nr_offset(slot),
4421 (nritems - slot) * sizeof(struct btrfs_item));
4424 btrfs_cpu_key_to_disk(&disk_key, new_key);
4425 btrfs_set_item_key(leaf, &disk_key, slot);
4427 new_item = btrfs_item_nr(slot);
4429 btrfs_set_item_offset(leaf, new_item, orig_offset);
4430 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4432 btrfs_set_item_offset(leaf, item,
4433 orig_offset + item_size - split_offset);
4434 btrfs_set_item_size(leaf, item, split_offset);
4436 btrfs_set_header_nritems(leaf, nritems + 1);
4438 /* write the data for the start of the original item */
4439 write_extent_buffer(leaf, buf,
4440 btrfs_item_ptr_offset(leaf, path->slots[0]),
4443 /* write the data for the new item */
4444 write_extent_buffer(leaf, buf + split_offset,
4445 btrfs_item_ptr_offset(leaf, slot),
4446 item_size - split_offset);
4447 btrfs_mark_buffer_dirty(leaf);
4449 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
4455 * This function splits a single item into two items,
4456 * giving 'new_key' to the new item and splitting the
4457 * old one at split_offset (from the start of the item).
4459 * The path may be released by this operation. After
4460 * the split, the path is pointing to the old item. The
4461 * new item is going to be in the same node as the old one.
4463 * Note, the item being split must be smaller enough to live alone on
4464 * a tree block with room for one extra struct btrfs_item
4466 * This allows us to split the item in place, keeping a lock on the
4467 * leaf the entire time.
4469 int btrfs_split_item(struct btrfs_trans_handle *trans,
4470 struct btrfs_root *root,
4471 struct btrfs_path *path,
4472 struct btrfs_key *new_key,
4473 unsigned long split_offset)
4476 ret = setup_leaf_for_split(trans, root, path,
4477 sizeof(struct btrfs_item));
4481 ret = split_item(trans, root, path, new_key, split_offset);
4486 * This function duplicate a item, giving 'new_key' to the new item.
4487 * It guarantees both items live in the same tree leaf and the new item
4488 * is contiguous with the original item.
4490 * This allows us to split file extent in place, keeping a lock on the
4491 * leaf the entire time.
4493 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4494 struct btrfs_root *root,
4495 struct btrfs_path *path,
4496 struct btrfs_key *new_key)
4498 struct extent_buffer *leaf;
4502 leaf = path->nodes[0];
4503 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4504 ret = setup_leaf_for_split(trans, root, path,
4505 item_size + sizeof(struct btrfs_item));
4510 setup_items_for_insert(root, path, new_key, &item_size,
4511 item_size, item_size +
4512 sizeof(struct btrfs_item), 1);
4513 leaf = path->nodes[0];
4514 memcpy_extent_buffer(leaf,
4515 btrfs_item_ptr_offset(leaf, path->slots[0]),
4516 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4522 * make the item pointed to by the path smaller. new_size indicates
4523 * how small to make it, and from_end tells us if we just chop bytes
4524 * off the end of the item or if we shift the item to chop bytes off
4527 void btrfs_truncate_item(struct btrfs_root *root, struct btrfs_path *path,
4528 u32 new_size, int from_end)
4531 struct extent_buffer *leaf;
4532 struct btrfs_item *item;
4534 unsigned int data_end;
4535 unsigned int old_data_start;
4536 unsigned int old_size;
4537 unsigned int size_diff;
4539 struct btrfs_map_token token;
4541 btrfs_init_map_token(&token);
4543 leaf = path->nodes[0];
4544 slot = path->slots[0];
4546 old_size = btrfs_item_size_nr(leaf, slot);
4547 if (old_size == new_size)
4550 nritems = btrfs_header_nritems(leaf);
4551 data_end = leaf_data_end(root, leaf);
4553 old_data_start = btrfs_item_offset_nr(leaf, slot);
4555 size_diff = old_size - new_size;
4558 BUG_ON(slot >= nritems);
4561 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4563 /* first correct the data pointers */
4564 for (i = slot; i < nritems; i++) {
4566 item = btrfs_item_nr(i);
4568 ioff = btrfs_token_item_offset(leaf, item, &token);
4569 btrfs_set_token_item_offset(leaf, item,
4570 ioff + size_diff, &token);
4573 /* shift the data */
4575 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4576 data_end + size_diff, btrfs_leaf_data(leaf) +
4577 data_end, old_data_start + new_size - data_end);
4579 struct btrfs_disk_key disk_key;
4582 btrfs_item_key(leaf, &disk_key, slot);
4584 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4586 struct btrfs_file_extent_item *fi;
4588 fi = btrfs_item_ptr(leaf, slot,
4589 struct btrfs_file_extent_item);
4590 fi = (struct btrfs_file_extent_item *)(
4591 (unsigned long)fi - size_diff);
4593 if (btrfs_file_extent_type(leaf, fi) ==
4594 BTRFS_FILE_EXTENT_INLINE) {
4595 ptr = btrfs_item_ptr_offset(leaf, slot);
4596 memmove_extent_buffer(leaf, ptr,
4598 BTRFS_FILE_EXTENT_INLINE_DATA_START);
4602 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4603 data_end + size_diff, btrfs_leaf_data(leaf) +
4604 data_end, old_data_start - data_end);
4606 offset = btrfs_disk_key_offset(&disk_key);
4607 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4608 btrfs_set_item_key(leaf, &disk_key, slot);
4610 fixup_low_keys(root, path, &disk_key, 1);
4613 item = btrfs_item_nr(slot);
4614 btrfs_set_item_size(leaf, item, new_size);
4615 btrfs_mark_buffer_dirty(leaf);
4617 if (btrfs_leaf_free_space(root, leaf) < 0) {
4618 btrfs_print_leaf(root, leaf);
4624 * make the item pointed to by the path bigger, data_size is the added size.
4626 void btrfs_extend_item(struct btrfs_root *root, struct btrfs_path *path,
4630 struct extent_buffer *leaf;
4631 struct btrfs_item *item;
4633 unsigned int data_end;
4634 unsigned int old_data;
4635 unsigned int old_size;
4637 struct btrfs_map_token token;
4639 btrfs_init_map_token(&token);
4641 leaf = path->nodes[0];
4643 nritems = btrfs_header_nritems(leaf);
4644 data_end = leaf_data_end(root, leaf);
4646 if (btrfs_leaf_free_space(root, leaf) < data_size) {
4647 btrfs_print_leaf(root, leaf);
4650 slot = path->slots[0];
4651 old_data = btrfs_item_end_nr(leaf, slot);
4654 if (slot >= nritems) {
4655 btrfs_print_leaf(root, leaf);
4656 btrfs_crit(root->fs_info, "slot %d too large, nritems %d",
4662 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4664 /* first correct the data pointers */
4665 for (i = slot; i < nritems; i++) {
4667 item = btrfs_item_nr(i);
4669 ioff = btrfs_token_item_offset(leaf, item, &token);
4670 btrfs_set_token_item_offset(leaf, item,
4671 ioff - data_size, &token);
4674 /* shift the data */
4675 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4676 data_end - data_size, btrfs_leaf_data(leaf) +
4677 data_end, old_data - data_end);
4679 data_end = old_data;
4680 old_size = btrfs_item_size_nr(leaf, slot);
4681 item = btrfs_item_nr(slot);
4682 btrfs_set_item_size(leaf, item, old_size + data_size);
4683 btrfs_mark_buffer_dirty(leaf);
4685 if (btrfs_leaf_free_space(root, leaf) < 0) {
4686 btrfs_print_leaf(root, leaf);
4692 * this is a helper for btrfs_insert_empty_items, the main goal here is
4693 * to save stack depth by doing the bulk of the work in a function
4694 * that doesn't call btrfs_search_slot
4696 void setup_items_for_insert(struct btrfs_root *root, struct btrfs_path *path,
4697 struct btrfs_key *cpu_key, u32 *data_size,
4698 u32 total_data, u32 total_size, int nr)
4700 struct btrfs_item *item;
4703 unsigned int data_end;
4704 struct btrfs_disk_key disk_key;
4705 struct extent_buffer *leaf;
4707 struct btrfs_map_token token;
4709 if (path->slots[0] == 0) {
4710 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4711 fixup_low_keys(root, path, &disk_key, 1);
4713 btrfs_unlock_up_safe(path, 1);
4715 btrfs_init_map_token(&token);
4717 leaf = path->nodes[0];
4718 slot = path->slots[0];
4720 nritems = btrfs_header_nritems(leaf);
4721 data_end = leaf_data_end(root, leaf);
4723 if (btrfs_leaf_free_space(root, leaf) < total_size) {
4724 btrfs_print_leaf(root, leaf);
4725 btrfs_crit(root->fs_info, "not enough freespace need %u have %d",
4726 total_size, btrfs_leaf_free_space(root, leaf));
4730 if (slot != nritems) {
4731 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4733 if (old_data < data_end) {
4734 btrfs_print_leaf(root, leaf);
4735 btrfs_crit(root->fs_info, "slot %d old_data %d data_end %d",
4736 slot, old_data, data_end);
4740 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4742 /* first correct the data pointers */
4743 for (i = slot; i < nritems; i++) {
4746 item = btrfs_item_nr( i);
4747 ioff = btrfs_token_item_offset(leaf, item, &token);
4748 btrfs_set_token_item_offset(leaf, item,
4749 ioff - total_data, &token);
4751 /* shift the items */
4752 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4753 btrfs_item_nr_offset(slot),
4754 (nritems - slot) * sizeof(struct btrfs_item));
4756 /* shift the data */
4757 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4758 data_end - total_data, btrfs_leaf_data(leaf) +
4759 data_end, old_data - data_end);
4760 data_end = old_data;
4763 /* setup the item for the new data */
4764 for (i = 0; i < nr; i++) {
4765 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4766 btrfs_set_item_key(leaf, &disk_key, slot + i);
4767 item = btrfs_item_nr(slot + i);
4768 btrfs_set_token_item_offset(leaf, item,
4769 data_end - data_size[i], &token);
4770 data_end -= data_size[i];
4771 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4774 btrfs_set_header_nritems(leaf, nritems + nr);
4775 btrfs_mark_buffer_dirty(leaf);
4777 if (btrfs_leaf_free_space(root, leaf) < 0) {
4778 btrfs_print_leaf(root, leaf);
4784 * Given a key and some data, insert items into the tree.
4785 * This does all the path init required, making room in the tree if needed.
4787 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4788 struct btrfs_root *root,
4789 struct btrfs_path *path,
4790 struct btrfs_key *cpu_key, u32 *data_size,
4799 for (i = 0; i < nr; i++)
4800 total_data += data_size[i];
4802 total_size = total_data + (nr * sizeof(struct btrfs_item));
4803 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4809 slot = path->slots[0];
4812 setup_items_for_insert(root, path, cpu_key, data_size,
4813 total_data, total_size, nr);
4818 * Given a key and some data, insert an item into the tree.
4819 * This does all the path init required, making room in the tree if needed.
4821 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
4822 *root, struct btrfs_key *cpu_key, void *data, u32
4826 struct btrfs_path *path;
4827 struct extent_buffer *leaf;
4830 path = btrfs_alloc_path();
4833 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4835 leaf = path->nodes[0];
4836 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4837 write_extent_buffer(leaf, data, ptr, data_size);
4838 btrfs_mark_buffer_dirty(leaf);
4840 btrfs_free_path(path);
4845 * delete the pointer from a given node.
4847 * the tree should have been previously balanced so the deletion does not
4850 static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
4851 int level, int slot)
4853 struct extent_buffer *parent = path->nodes[level];
4857 nritems = btrfs_header_nritems(parent);
4858 if (slot != nritems - 1) {
4860 tree_mod_log_eb_move(root->fs_info, parent, slot,
4861 slot + 1, nritems - slot - 1);
4862 memmove_extent_buffer(parent,
4863 btrfs_node_key_ptr_offset(slot),
4864 btrfs_node_key_ptr_offset(slot + 1),
4865 sizeof(struct btrfs_key_ptr) *
4866 (nritems - slot - 1));
4868 ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
4869 MOD_LOG_KEY_REMOVE, GFP_NOFS);
4874 btrfs_set_header_nritems(parent, nritems);
4875 if (nritems == 0 && parent == root->node) {
4876 BUG_ON(btrfs_header_level(root->node) != 1);
4877 /* just turn the root into a leaf and break */
4878 btrfs_set_header_level(root->node, 0);
4879 } else if (slot == 0) {
4880 struct btrfs_disk_key disk_key;
4882 btrfs_node_key(parent, &disk_key, 0);
4883 fixup_low_keys(root, path, &disk_key, level + 1);
4885 btrfs_mark_buffer_dirty(parent);
4889 * a helper function to delete the leaf pointed to by path->slots[1] and
4892 * This deletes the pointer in path->nodes[1] and frees the leaf
4893 * block extent. zero is returned if it all worked out, < 0 otherwise.
4895 * The path must have already been setup for deleting the leaf, including
4896 * all the proper balancing. path->nodes[1] must be locked.
4898 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4899 struct btrfs_root *root,
4900 struct btrfs_path *path,
4901 struct extent_buffer *leaf)
4903 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4904 del_ptr(root, path, 1, path->slots[1]);
4907 * btrfs_free_extent is expensive, we want to make sure we
4908 * aren't holding any locks when we call it
4910 btrfs_unlock_up_safe(path, 0);
4912 root_sub_used(root, leaf->len);
4914 extent_buffer_get(leaf);
4915 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4916 free_extent_buffer_stale(leaf);
4919 * delete the item at the leaf level in path. If that empties
4920 * the leaf, remove it from the tree
4922 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4923 struct btrfs_path *path, int slot, int nr)
4925 struct extent_buffer *leaf;
4926 struct btrfs_item *item;
4933 struct btrfs_map_token token;
4935 btrfs_init_map_token(&token);
4937 leaf = path->nodes[0];
4938 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4940 for (i = 0; i < nr; i++)
4941 dsize += btrfs_item_size_nr(leaf, slot + i);
4943 nritems = btrfs_header_nritems(leaf);
4945 if (slot + nr != nritems) {
4946 int data_end = leaf_data_end(root, leaf);
4948 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4950 btrfs_leaf_data(leaf) + data_end,
4951 last_off - data_end);
4953 for (i = slot + nr; i < nritems; i++) {
4956 item = btrfs_item_nr(i);
4957 ioff = btrfs_token_item_offset(leaf, item, &token);
4958 btrfs_set_token_item_offset(leaf, item,
4959 ioff + dsize, &token);
4962 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4963 btrfs_item_nr_offset(slot + nr),
4964 sizeof(struct btrfs_item) *
4965 (nritems - slot - nr));
4967 btrfs_set_header_nritems(leaf, nritems - nr);
4970 /* delete the leaf if we've emptied it */
4972 if (leaf == root->node) {
4973 btrfs_set_header_level(leaf, 0);
4975 btrfs_set_path_blocking(path);
4976 clean_tree_block(trans, root, leaf);
4977 btrfs_del_leaf(trans, root, path, leaf);
4980 int used = leaf_space_used(leaf, 0, nritems);
4982 struct btrfs_disk_key disk_key;
4984 btrfs_item_key(leaf, &disk_key, 0);
4985 fixup_low_keys(root, path, &disk_key, 1);
4988 /* delete the leaf if it is mostly empty */
4989 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
4990 /* push_leaf_left fixes the path.
4991 * make sure the path still points to our leaf
4992 * for possible call to del_ptr below
4994 slot = path->slots[1];
4995 extent_buffer_get(leaf);
4997 btrfs_set_path_blocking(path);
4998 wret = push_leaf_left(trans, root, path, 1, 1,
5000 if (wret < 0 && wret != -ENOSPC)
5003 if (path->nodes[0] == leaf &&
5004 btrfs_header_nritems(leaf)) {
5005 wret = push_leaf_right(trans, root, path, 1,
5007 if (wret < 0 && wret != -ENOSPC)
5011 if (btrfs_header_nritems(leaf) == 0) {
5012 path->slots[1] = slot;
5013 btrfs_del_leaf(trans, root, path, leaf);
5014 free_extent_buffer(leaf);
5017 /* if we're still in the path, make sure
5018 * we're dirty. Otherwise, one of the
5019 * push_leaf functions must have already
5020 * dirtied this buffer
5022 if (path->nodes[0] == leaf)
5023 btrfs_mark_buffer_dirty(leaf);
5024 free_extent_buffer(leaf);
5027 btrfs_mark_buffer_dirty(leaf);
5034 * search the tree again to find a leaf with lesser keys
5035 * returns 0 if it found something or 1 if there are no lesser leaves.
5036 * returns < 0 on io errors.
5038 * This may release the path, and so you may lose any locks held at the
5041 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
5043 struct btrfs_key key;
5044 struct btrfs_disk_key found_key;
5047 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
5049 if (key.offset > 0) {
5051 } else if (key.type > 0) {
5053 key.offset = (u64)-1;
5054 } else if (key.objectid > 0) {
5057 key.offset = (u64)-1;
5062 btrfs_release_path(path);
5063 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5066 btrfs_item_key(path->nodes[0], &found_key, 0);
5067 ret = comp_keys(&found_key, &key);
5069 * We might have had an item with the previous key in the tree right
5070 * before we released our path. And after we released our path, that
5071 * item might have been pushed to the first slot (0) of the leaf we
5072 * were holding due to a tree balance. Alternatively, an item with the
5073 * previous key can exist as the only element of a leaf (big fat item).
5074 * Therefore account for these 2 cases, so that our callers (like
5075 * btrfs_previous_item) don't miss an existing item with a key matching
5076 * the previous key we computed above.
5084 * A helper function to walk down the tree starting at min_key, and looking
5085 * for nodes or leaves that are have a minimum transaction id.
5086 * This is used by the btree defrag code, and tree logging
5088 * This does not cow, but it does stuff the starting key it finds back
5089 * into min_key, so you can call btrfs_search_slot with cow=1 on the
5090 * key and get a writable path.
5092 * This does lock as it descends, and path->keep_locks should be set
5093 * to 1 by the caller.
5095 * This honors path->lowest_level to prevent descent past a given level
5098 * min_trans indicates the oldest transaction that you are interested
5099 * in walking through. Any nodes or leaves older than min_trans are
5100 * skipped over (without reading them).
5102 * returns zero if something useful was found, < 0 on error and 1 if there
5103 * was nothing in the tree that matched the search criteria.
5105 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
5106 struct btrfs_path *path,
5109 struct extent_buffer *cur;
5110 struct btrfs_key found_key;
5116 int keep_locks = path->keep_locks;
5118 path->keep_locks = 1;
5120 cur = btrfs_read_lock_root_node(root);
5121 level = btrfs_header_level(cur);
5122 WARN_ON(path->nodes[level]);
5123 path->nodes[level] = cur;
5124 path->locks[level] = BTRFS_READ_LOCK;
5126 if (btrfs_header_generation(cur) < min_trans) {
5131 nritems = btrfs_header_nritems(cur);
5132 level = btrfs_header_level(cur);
5133 sret = bin_search(cur, min_key, level, &slot);
5135 /* at the lowest level, we're done, setup the path and exit */
5136 if (level == path->lowest_level) {
5137 if (slot >= nritems)
5140 path->slots[level] = slot;
5141 btrfs_item_key_to_cpu(cur, &found_key, slot);
5144 if (sret && slot > 0)
5147 * check this node pointer against the min_trans parameters.
5148 * If it is too old, old, skip to the next one.
5150 while (slot < nritems) {
5153 gen = btrfs_node_ptr_generation(cur, slot);
5154 if (gen < min_trans) {
5162 * we didn't find a candidate key in this node, walk forward
5163 * and find another one
5165 if (slot >= nritems) {
5166 path->slots[level] = slot;
5167 btrfs_set_path_blocking(path);
5168 sret = btrfs_find_next_key(root, path, min_key, level,
5171 btrfs_release_path(path);
5177 /* save our key for returning back */
5178 btrfs_node_key_to_cpu(cur, &found_key, slot);
5179 path->slots[level] = slot;
5180 if (level == path->lowest_level) {
5184 btrfs_set_path_blocking(path);
5185 cur = read_node_slot(root, cur, slot);
5186 BUG_ON(!cur); /* -ENOMEM */
5188 btrfs_tree_read_lock(cur);
5190 path->locks[level - 1] = BTRFS_READ_LOCK;
5191 path->nodes[level - 1] = cur;
5192 unlock_up(path, level, 1, 0, NULL);
5193 btrfs_clear_path_blocking(path, NULL, 0);
5196 path->keep_locks = keep_locks;
5198 btrfs_unlock_up_safe(path, path->lowest_level + 1);
5199 btrfs_set_path_blocking(path);
5200 memcpy(min_key, &found_key, sizeof(found_key));
5205 static void tree_move_down(struct btrfs_root *root,
5206 struct btrfs_path *path,
5207 int *level, int root_level)
5209 BUG_ON(*level == 0);
5210 path->nodes[*level - 1] = read_node_slot(root, path->nodes[*level],
5211 path->slots[*level]);
5212 path->slots[*level - 1] = 0;
5216 static int tree_move_next_or_upnext(struct btrfs_root *root,
5217 struct btrfs_path *path,
5218 int *level, int root_level)
5222 nritems = btrfs_header_nritems(path->nodes[*level]);
5224 path->slots[*level]++;
5226 while (path->slots[*level] >= nritems) {
5227 if (*level == root_level)
5231 path->slots[*level] = 0;
5232 free_extent_buffer(path->nodes[*level]);
5233 path->nodes[*level] = NULL;
5235 path->slots[*level]++;
5237 nritems = btrfs_header_nritems(path->nodes[*level]);
5244 * Returns 1 if it had to move up and next. 0 is returned if it moved only next
5247 static int tree_advance(struct btrfs_root *root,
5248 struct btrfs_path *path,
5249 int *level, int root_level,
5251 struct btrfs_key *key)
5255 if (*level == 0 || !allow_down) {
5256 ret = tree_move_next_or_upnext(root, path, level, root_level);
5258 tree_move_down(root, path, level, root_level);
5263 btrfs_item_key_to_cpu(path->nodes[*level], key,
5264 path->slots[*level]);
5266 btrfs_node_key_to_cpu(path->nodes[*level], key,
5267 path->slots[*level]);
5272 static int tree_compare_item(struct btrfs_root *left_root,
5273 struct btrfs_path *left_path,
5274 struct btrfs_path *right_path,
5279 unsigned long off1, off2;
5281 len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
5282 len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
5286 off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
5287 off2 = btrfs_item_ptr_offset(right_path->nodes[0],
5288 right_path->slots[0]);
5290 read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
5292 cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
5299 #define ADVANCE_ONLY_NEXT -1
5302 * This function compares two trees and calls the provided callback for
5303 * every changed/new/deleted item it finds.
5304 * If shared tree blocks are encountered, whole subtrees are skipped, making
5305 * the compare pretty fast on snapshotted subvolumes.
5307 * This currently works on commit roots only. As commit roots are read only,
5308 * we don't do any locking. The commit roots are protected with transactions.
5309 * Transactions are ended and rejoined when a commit is tried in between.
5311 * This function checks for modifications done to the trees while comparing.
5312 * If it detects a change, it aborts immediately.
5314 int btrfs_compare_trees(struct btrfs_root *left_root,
5315 struct btrfs_root *right_root,
5316 btrfs_changed_cb_t changed_cb, void *ctx)
5320 struct btrfs_path *left_path = NULL;
5321 struct btrfs_path *right_path = NULL;
5322 struct btrfs_key left_key;
5323 struct btrfs_key right_key;
5324 char *tmp_buf = NULL;
5325 int left_root_level;
5326 int right_root_level;
5329 int left_end_reached;
5330 int right_end_reached;
5338 left_path = btrfs_alloc_path();
5343 right_path = btrfs_alloc_path();
5349 tmp_buf = kmalloc(left_root->nodesize, GFP_NOFS);
5355 left_path->search_commit_root = 1;
5356 left_path->skip_locking = 1;
5357 right_path->search_commit_root = 1;
5358 right_path->skip_locking = 1;
5361 * Strategy: Go to the first items of both trees. Then do
5363 * If both trees are at level 0
5364 * Compare keys of current items
5365 * If left < right treat left item as new, advance left tree
5367 * If left > right treat right item as deleted, advance right tree
5369 * If left == right do deep compare of items, treat as changed if
5370 * needed, advance both trees and repeat
5371 * If both trees are at the same level but not at level 0
5372 * Compare keys of current nodes/leafs
5373 * If left < right advance left tree and repeat
5374 * If left > right advance right tree and repeat
5375 * If left == right compare blockptrs of the next nodes/leafs
5376 * If they match advance both trees but stay at the same level
5378 * If they don't match advance both trees while allowing to go
5380 * If tree levels are different
5381 * Advance the tree that needs it and repeat
5383 * Advancing a tree means:
5384 * If we are at level 0, try to go to the next slot. If that's not
5385 * possible, go one level up and repeat. Stop when we found a level
5386 * where we could go to the next slot. We may at this point be on a
5389 * If we are not at level 0 and not on shared tree blocks, go one
5392 * If we are not at level 0 and on shared tree blocks, go one slot to
5393 * the right if possible or go up and right.
5396 down_read(&left_root->fs_info->commit_root_sem);
5397 left_level = btrfs_header_level(left_root->commit_root);
5398 left_root_level = left_level;
5399 left_path->nodes[left_level] = left_root->commit_root;
5400 extent_buffer_get(left_path->nodes[left_level]);
5402 right_level = btrfs_header_level(right_root->commit_root);
5403 right_root_level = right_level;
5404 right_path->nodes[right_level] = right_root->commit_root;
5405 extent_buffer_get(right_path->nodes[right_level]);
5406 up_read(&left_root->fs_info->commit_root_sem);
5408 if (left_level == 0)
5409 btrfs_item_key_to_cpu(left_path->nodes[left_level],
5410 &left_key, left_path->slots[left_level]);
5412 btrfs_node_key_to_cpu(left_path->nodes[left_level],
5413 &left_key, left_path->slots[left_level]);
5414 if (right_level == 0)
5415 btrfs_item_key_to_cpu(right_path->nodes[right_level],
5416 &right_key, right_path->slots[right_level]);
5418 btrfs_node_key_to_cpu(right_path->nodes[right_level],
5419 &right_key, right_path->slots[right_level]);
5421 left_end_reached = right_end_reached = 0;
5422 advance_left = advance_right = 0;
5425 if (advance_left && !left_end_reached) {
5426 ret = tree_advance(left_root, left_path, &left_level,
5428 advance_left != ADVANCE_ONLY_NEXT,
5431 left_end_reached = ADVANCE;
5434 if (advance_right && !right_end_reached) {
5435 ret = tree_advance(right_root, right_path, &right_level,
5437 advance_right != ADVANCE_ONLY_NEXT,
5440 right_end_reached = ADVANCE;
5444 if (left_end_reached && right_end_reached) {
5447 } else if (left_end_reached) {
5448 if (right_level == 0) {
5449 ret = changed_cb(left_root, right_root,
5450 left_path, right_path,
5452 BTRFS_COMPARE_TREE_DELETED,
5457 advance_right = ADVANCE;
5459 } else if (right_end_reached) {
5460 if (left_level == 0) {
5461 ret = changed_cb(left_root, right_root,
5462 left_path, right_path,
5464 BTRFS_COMPARE_TREE_NEW,
5469 advance_left = ADVANCE;
5473 if (left_level == 0 && right_level == 0) {
5474 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5476 ret = changed_cb(left_root, right_root,
5477 left_path, right_path,
5479 BTRFS_COMPARE_TREE_NEW,
5483 advance_left = ADVANCE;
5484 } else if (cmp > 0) {
5485 ret = changed_cb(left_root, right_root,
5486 left_path, right_path,
5488 BTRFS_COMPARE_TREE_DELETED,
5492 advance_right = ADVANCE;
5494 enum btrfs_compare_tree_result result;
5496 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
5497 ret = tree_compare_item(left_root, left_path,
5498 right_path, tmp_buf);
5500 result = BTRFS_COMPARE_TREE_CHANGED;
5502 result = BTRFS_COMPARE_TREE_SAME;
5503 ret = changed_cb(left_root, right_root,
5504 left_path, right_path,
5505 &left_key, result, ctx);
5508 advance_left = ADVANCE;
5509 advance_right = ADVANCE;
5511 } else if (left_level == right_level) {
5512 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5514 advance_left = ADVANCE;
5515 } else if (cmp > 0) {
5516 advance_right = ADVANCE;
5518 left_blockptr = btrfs_node_blockptr(
5519 left_path->nodes[left_level],
5520 left_path->slots[left_level]);
5521 right_blockptr = btrfs_node_blockptr(
5522 right_path->nodes[right_level],
5523 right_path->slots[right_level]);
5524 left_gen = btrfs_node_ptr_generation(
5525 left_path->nodes[left_level],
5526 left_path->slots[left_level]);
5527 right_gen = btrfs_node_ptr_generation(
5528 right_path->nodes[right_level],
5529 right_path->slots[right_level]);
5530 if (left_blockptr == right_blockptr &&
5531 left_gen == right_gen) {
5533 * As we're on a shared block, don't
5534 * allow to go deeper.
5536 advance_left = ADVANCE_ONLY_NEXT;
5537 advance_right = ADVANCE_ONLY_NEXT;
5539 advance_left = ADVANCE;
5540 advance_right = ADVANCE;
5543 } else if (left_level < right_level) {
5544 advance_right = ADVANCE;
5546 advance_left = ADVANCE;
5551 btrfs_free_path(left_path);
5552 btrfs_free_path(right_path);
5558 * this is similar to btrfs_next_leaf, but does not try to preserve
5559 * and fixup the path. It looks for and returns the next key in the
5560 * tree based on the current path and the min_trans parameters.
5562 * 0 is returned if another key is found, < 0 if there are any errors
5563 * and 1 is returned if there are no higher keys in the tree
5565 * path->keep_locks should be set to 1 on the search made before
5566 * calling this function.
5568 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5569 struct btrfs_key *key, int level, u64 min_trans)
5572 struct extent_buffer *c;
5574 WARN_ON(!path->keep_locks);
5575 while (level < BTRFS_MAX_LEVEL) {
5576 if (!path->nodes[level])
5579 slot = path->slots[level] + 1;
5580 c = path->nodes[level];
5582 if (slot >= btrfs_header_nritems(c)) {
5585 struct btrfs_key cur_key;
5586 if (level + 1 >= BTRFS_MAX_LEVEL ||
5587 !path->nodes[level + 1])
5590 if (path->locks[level + 1]) {
5595 slot = btrfs_header_nritems(c) - 1;
5597 btrfs_item_key_to_cpu(c, &cur_key, slot);
5599 btrfs_node_key_to_cpu(c, &cur_key, slot);
5601 orig_lowest = path->lowest_level;
5602 btrfs_release_path(path);
5603 path->lowest_level = level;
5604 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5606 path->lowest_level = orig_lowest;
5610 c = path->nodes[level];
5611 slot = path->slots[level];
5618 btrfs_item_key_to_cpu(c, key, slot);
5620 u64 gen = btrfs_node_ptr_generation(c, slot);
5622 if (gen < min_trans) {
5626 btrfs_node_key_to_cpu(c, key, slot);
5634 * search the tree again to find a leaf with greater keys
5635 * returns 0 if it found something or 1 if there are no greater leaves.
5636 * returns < 0 on io errors.
5638 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5640 return btrfs_next_old_leaf(root, path, 0);
5643 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5648 struct extent_buffer *c;
5649 struct extent_buffer *next;
5650 struct btrfs_key key;
5653 int old_spinning = path->leave_spinning;
5654 int next_rw_lock = 0;
5656 nritems = btrfs_header_nritems(path->nodes[0]);
5660 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5665 btrfs_release_path(path);
5667 path->keep_locks = 1;
5668 path->leave_spinning = 1;
5671 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5673 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5674 path->keep_locks = 0;
5679 nritems = btrfs_header_nritems(path->nodes[0]);
5681 * by releasing the path above we dropped all our locks. A balance
5682 * could have added more items next to the key that used to be
5683 * at the very end of the block. So, check again here and
5684 * advance the path if there are now more items available.
5686 if (nritems > 0 && path->slots[0] < nritems - 1) {
5693 * So the above check misses one case:
5694 * - after releasing the path above, someone has removed the item that
5695 * used to be at the very end of the block, and balance between leafs
5696 * gets another one with bigger key.offset to replace it.
5698 * This one should be returned as well, or we can get leaf corruption
5699 * later(esp. in __btrfs_drop_extents()).
5701 * And a bit more explanation about this check,
5702 * with ret > 0, the key isn't found, the path points to the slot
5703 * where it should be inserted, so the path->slots[0] item must be the
5706 if (nritems > 0 && ret > 0 && path->slots[0] == nritems - 1) {
5711 while (level < BTRFS_MAX_LEVEL) {
5712 if (!path->nodes[level]) {
5717 slot = path->slots[level] + 1;
5718 c = path->nodes[level];
5719 if (slot >= btrfs_header_nritems(c)) {
5721 if (level == BTRFS_MAX_LEVEL) {
5729 btrfs_tree_unlock_rw(next, next_rw_lock);
5730 free_extent_buffer(next);
5734 next_rw_lock = path->locks[level];
5735 ret = read_block_for_search(NULL, root, path, &next, level,
5741 btrfs_release_path(path);
5745 if (!path->skip_locking) {
5746 ret = btrfs_try_tree_read_lock(next);
5747 if (!ret && time_seq) {
5749 * If we don't get the lock, we may be racing
5750 * with push_leaf_left, holding that lock while
5751 * itself waiting for the leaf we've currently
5752 * locked. To solve this situation, we give up
5753 * on our lock and cycle.
5755 free_extent_buffer(next);
5756 btrfs_release_path(path);
5761 btrfs_set_path_blocking(path);
5762 btrfs_tree_read_lock(next);
5763 btrfs_clear_path_blocking(path, next,
5766 next_rw_lock = BTRFS_READ_LOCK;
5770 path->slots[level] = slot;
5773 c = path->nodes[level];
5774 if (path->locks[level])
5775 btrfs_tree_unlock_rw(c, path->locks[level]);
5777 free_extent_buffer(c);
5778 path->nodes[level] = next;
5779 path->slots[level] = 0;
5780 if (!path->skip_locking)
5781 path->locks[level] = next_rw_lock;
5785 ret = read_block_for_search(NULL, root, path, &next, level,
5791 btrfs_release_path(path);
5795 if (!path->skip_locking) {
5796 ret = btrfs_try_tree_read_lock(next);
5798 btrfs_set_path_blocking(path);
5799 btrfs_tree_read_lock(next);
5800 btrfs_clear_path_blocking(path, next,
5803 next_rw_lock = BTRFS_READ_LOCK;
5808 unlock_up(path, 0, 1, 0, NULL);
5809 path->leave_spinning = old_spinning;
5811 btrfs_set_path_blocking(path);
5817 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5818 * searching until it gets past min_objectid or finds an item of 'type'
5820 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5822 int btrfs_previous_item(struct btrfs_root *root,
5823 struct btrfs_path *path, u64 min_objectid,
5826 struct btrfs_key found_key;
5827 struct extent_buffer *leaf;
5832 if (path->slots[0] == 0) {
5833 btrfs_set_path_blocking(path);
5834 ret = btrfs_prev_leaf(root, path);
5840 leaf = path->nodes[0];
5841 nritems = btrfs_header_nritems(leaf);
5844 if (path->slots[0] == nritems)
5847 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5848 if (found_key.objectid < min_objectid)
5850 if (found_key.type == type)
5852 if (found_key.objectid == min_objectid &&
5853 found_key.type < type)
5860 * search in extent tree to find a previous Metadata/Data extent item with
5863 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5865 int btrfs_previous_extent_item(struct btrfs_root *root,
5866 struct btrfs_path *path, u64 min_objectid)
5868 struct btrfs_key found_key;
5869 struct extent_buffer *leaf;
5874 if (path->slots[0] == 0) {
5875 btrfs_set_path_blocking(path);
5876 ret = btrfs_prev_leaf(root, path);
5882 leaf = path->nodes[0];
5883 nritems = btrfs_header_nritems(leaf);
5886 if (path->slots[0] == nritems)
5889 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5890 if (found_key.objectid < min_objectid)
5892 if (found_key.type == BTRFS_EXTENT_ITEM_KEY ||
5893 found_key.type == BTRFS_METADATA_ITEM_KEY)
5895 if (found_key.objectid == min_objectid &&
5896 found_key.type < BTRFS_EXTENT_ITEM_KEY)