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1 /*
2 * Copyright (C) 2007,2008 Oracle. All rights reserved.
3 *
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.
7 *
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.
12 *
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.
17 */
18
19 #include <linux/sched.h>
20 #include <linux/slab.h>
21 #include <linux/rbtree.h>
22 #include "ctree.h"
23 #include "disk-io.h"
24 #include "transaction.h"
25 #include "print-tree.h"
26 #include "locking.h"
27
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_trans_handle *trans, struct btrfs_root *root,
41 struct btrfs_path *path, int level, int slot);
42 static void tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
43 struct extent_buffer *eb);
44 struct extent_buffer *read_old_tree_block(struct btrfs_root *root, u64 bytenr,
45 u32 blocksize, u64 parent_transid,
46 u64 time_seq);
47 struct extent_buffer *btrfs_find_old_tree_block(struct btrfs_root *root,
48 u64 bytenr, u32 blocksize,
49 u64 time_seq);
50
51 struct btrfs_path *btrfs_alloc_path(void)
52 {
53 struct btrfs_path *path;
54 path = kmem_cache_zalloc(btrfs_path_cachep, GFP_NOFS);
55 return path;
56 }
57
58 /*
59 * set all locked nodes in the path to blocking locks. This should
60 * be done before scheduling
61 */
62 noinline void btrfs_set_path_blocking(struct btrfs_path *p)
63 {
64 int i;
65 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
66 if (!p->nodes[i] || !p->locks[i])
67 continue;
68 btrfs_set_lock_blocking_rw(p->nodes[i], p->locks[i]);
69 if (p->locks[i] == BTRFS_READ_LOCK)
70 p->locks[i] = BTRFS_READ_LOCK_BLOCKING;
71 else if (p->locks[i] == BTRFS_WRITE_LOCK)
72 p->locks[i] = BTRFS_WRITE_LOCK_BLOCKING;
73 }
74 }
75
76 /*
77 * reset all the locked nodes in the patch to spinning locks.
78 *
79 * held is used to keep lockdep happy, when lockdep is enabled
80 * we set held to a blocking lock before we go around and
81 * retake all the spinlocks in the path. You can safely use NULL
82 * for held
83 */
84 noinline void btrfs_clear_path_blocking(struct btrfs_path *p,
85 struct extent_buffer *held, int held_rw)
86 {
87 int i;
88
89 #ifdef CONFIG_DEBUG_LOCK_ALLOC
90 /* lockdep really cares that we take all of these spinlocks
91 * in the right order. If any of the locks in the path are not
92 * currently blocking, it is going to complain. So, make really
93 * really sure by forcing the path to blocking before we clear
94 * the path blocking.
95 */
96 if (held) {
97 btrfs_set_lock_blocking_rw(held, held_rw);
98 if (held_rw == BTRFS_WRITE_LOCK)
99 held_rw = BTRFS_WRITE_LOCK_BLOCKING;
100 else if (held_rw == BTRFS_READ_LOCK)
101 held_rw = BTRFS_READ_LOCK_BLOCKING;
102 }
103 btrfs_set_path_blocking(p);
104 #endif
105
106 for (i = BTRFS_MAX_LEVEL - 1; i >= 0; i--) {
107 if (p->nodes[i] && p->locks[i]) {
108 btrfs_clear_lock_blocking_rw(p->nodes[i], p->locks[i]);
109 if (p->locks[i] == BTRFS_WRITE_LOCK_BLOCKING)
110 p->locks[i] = BTRFS_WRITE_LOCK;
111 else if (p->locks[i] == BTRFS_READ_LOCK_BLOCKING)
112 p->locks[i] = BTRFS_READ_LOCK;
113 }
114 }
115
116 #ifdef CONFIG_DEBUG_LOCK_ALLOC
117 if (held)
118 btrfs_clear_lock_blocking_rw(held, held_rw);
119 #endif
120 }
121
122 /* this also releases the path */
123 void btrfs_free_path(struct btrfs_path *p)
124 {
125 if (!p)
126 return;
127 btrfs_release_path(p);
128 kmem_cache_free(btrfs_path_cachep, p);
129 }
130
131 /*
132 * path release drops references on the extent buffers in the path
133 * and it drops any locks held by this path
134 *
135 * It is safe to call this on paths that no locks or extent buffers held.
136 */
137 noinline void btrfs_release_path(struct btrfs_path *p)
138 {
139 int i;
140
141 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
142 p->slots[i] = 0;
143 if (!p->nodes[i])
144 continue;
145 if (p->locks[i]) {
146 btrfs_tree_unlock_rw(p->nodes[i], p->locks[i]);
147 p->locks[i] = 0;
148 }
149 free_extent_buffer(p->nodes[i]);
150 p->nodes[i] = NULL;
151 }
152 }
153
154 /*
155 * safely gets a reference on the root node of a tree. A lock
156 * is not taken, so a concurrent writer may put a different node
157 * at the root of the tree. See btrfs_lock_root_node for the
158 * looping required.
159 *
160 * The extent buffer returned by this has a reference taken, so
161 * it won't disappear. It may stop being the root of the tree
162 * at any time because there are no locks held.
163 */
164 struct extent_buffer *btrfs_root_node(struct btrfs_root *root)
165 {
166 struct extent_buffer *eb;
167
168 while (1) {
169 rcu_read_lock();
170 eb = rcu_dereference(root->node);
171
172 /*
173 * RCU really hurts here, we could free up the root node because
174 * it was cow'ed but we may not get the new root node yet so do
175 * the inc_not_zero dance and if it doesn't work then
176 * synchronize_rcu and try again.
177 */
178 if (atomic_inc_not_zero(&eb->refs)) {
179 rcu_read_unlock();
180 break;
181 }
182 rcu_read_unlock();
183 synchronize_rcu();
184 }
185 return eb;
186 }
187
188 /* loop around taking references on and locking the root node of the
189 * tree until you end up with a lock on the root. A locked buffer
190 * is returned, with a reference held.
191 */
192 struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root)
193 {
194 struct extent_buffer *eb;
195
196 while (1) {
197 eb = btrfs_root_node(root);
198 btrfs_tree_lock(eb);
199 if (eb == root->node)
200 break;
201 btrfs_tree_unlock(eb);
202 free_extent_buffer(eb);
203 }
204 return eb;
205 }
206
207 /* loop around taking references on and locking the root node of the
208 * tree until you end up with a lock on the root. A locked buffer
209 * is returned, with a reference held.
210 */
211 struct extent_buffer *btrfs_read_lock_root_node(struct btrfs_root *root)
212 {
213 struct extent_buffer *eb;
214
215 while (1) {
216 eb = btrfs_root_node(root);
217 btrfs_tree_read_lock(eb);
218 if (eb == root->node)
219 break;
220 btrfs_tree_read_unlock(eb);
221 free_extent_buffer(eb);
222 }
223 return eb;
224 }
225
226 /* cowonly root (everything not a reference counted cow subvolume), just get
227 * put onto a simple dirty list. transaction.c walks this to make sure they
228 * get properly updated on disk.
229 */
230 static void add_root_to_dirty_list(struct btrfs_root *root)
231 {
232 spin_lock(&root->fs_info->trans_lock);
233 if (root->track_dirty && list_empty(&root->dirty_list)) {
234 list_add(&root->dirty_list,
235 &root->fs_info->dirty_cowonly_roots);
236 }
237 spin_unlock(&root->fs_info->trans_lock);
238 }
239
240 /*
241 * used by snapshot creation to make a copy of a root for a tree with
242 * a given objectid. The buffer with the new root node is returned in
243 * cow_ret, and this func returns zero on success or a negative error code.
244 */
245 int btrfs_copy_root(struct btrfs_trans_handle *trans,
246 struct btrfs_root *root,
247 struct extent_buffer *buf,
248 struct extent_buffer **cow_ret, u64 new_root_objectid)
249 {
250 struct extent_buffer *cow;
251 int ret = 0;
252 int level;
253 struct btrfs_disk_key disk_key;
254
255 WARN_ON(root->ref_cows && trans->transid !=
256 root->fs_info->running_transaction->transid);
257 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
258
259 level = btrfs_header_level(buf);
260 if (level == 0)
261 btrfs_item_key(buf, &disk_key, 0);
262 else
263 btrfs_node_key(buf, &disk_key, 0);
264
265 cow = btrfs_alloc_free_block(trans, root, buf->len, 0,
266 new_root_objectid, &disk_key, level,
267 buf->start, 0);
268 if (IS_ERR(cow))
269 return PTR_ERR(cow);
270
271 copy_extent_buffer(cow, buf, 0, 0, cow->len);
272 btrfs_set_header_bytenr(cow, cow->start);
273 btrfs_set_header_generation(cow, trans->transid);
274 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
275 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
276 BTRFS_HEADER_FLAG_RELOC);
277 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
278 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
279 else
280 btrfs_set_header_owner(cow, new_root_objectid);
281
282 write_extent_buffer(cow, root->fs_info->fsid,
283 (unsigned long)btrfs_header_fsid(cow),
284 BTRFS_FSID_SIZE);
285
286 WARN_ON(btrfs_header_generation(buf) > trans->transid);
287 if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID)
288 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
289 else
290 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
291
292 if (ret)
293 return ret;
294
295 btrfs_mark_buffer_dirty(cow);
296 *cow_ret = cow;
297 return 0;
298 }
299
300 enum mod_log_op {
301 MOD_LOG_KEY_REPLACE,
302 MOD_LOG_KEY_ADD,
303 MOD_LOG_KEY_REMOVE,
304 MOD_LOG_KEY_REMOVE_WHILE_FREEING,
305 MOD_LOG_KEY_REMOVE_WHILE_MOVING,
306 MOD_LOG_MOVE_KEYS,
307 MOD_LOG_ROOT_REPLACE,
308 };
309
310 struct tree_mod_move {
311 int dst_slot;
312 int nr_items;
313 };
314
315 struct tree_mod_root {
316 u64 logical;
317 u8 level;
318 };
319
320 struct tree_mod_elem {
321 struct rb_node node;
322 u64 index; /* shifted logical */
323 u64 seq;
324 enum mod_log_op op;
325
326 /* this is used for MOD_LOG_KEY_* and MOD_LOG_MOVE_KEYS operations */
327 int slot;
328
329 /* this is used for MOD_LOG_KEY* and MOD_LOG_ROOT_REPLACE */
330 u64 generation;
331
332 /* those are used for op == MOD_LOG_KEY_{REPLACE,REMOVE} */
333 struct btrfs_disk_key key;
334 u64 blockptr;
335
336 /* this is used for op == MOD_LOG_MOVE_KEYS */
337 struct tree_mod_move move;
338
339 /* this is used for op == MOD_LOG_ROOT_REPLACE */
340 struct tree_mod_root old_root;
341 };
342
343 static inline void tree_mod_log_read_lock(struct btrfs_fs_info *fs_info)
344 {
345 read_lock(&fs_info->tree_mod_log_lock);
346 }
347
348 static inline void tree_mod_log_read_unlock(struct btrfs_fs_info *fs_info)
349 {
350 read_unlock(&fs_info->tree_mod_log_lock);
351 }
352
353 static inline void tree_mod_log_write_lock(struct btrfs_fs_info *fs_info)
354 {
355 write_lock(&fs_info->tree_mod_log_lock);
356 }
357
358 static inline void tree_mod_log_write_unlock(struct btrfs_fs_info *fs_info)
359 {
360 write_unlock(&fs_info->tree_mod_log_lock);
361 }
362
363 /*
364 * This adds a new blocker to the tree mod log's blocker list if the @elem
365 * passed does not already have a sequence number set. So when a caller expects
366 * to record tree modifications, it should ensure to set elem->seq to zero
367 * before calling btrfs_get_tree_mod_seq.
368 * Returns a fresh, unused tree log modification sequence number, even if no new
369 * blocker was added.
370 */
371 u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
372 struct seq_list *elem)
373 {
374 u64 seq;
375
376 tree_mod_log_write_lock(fs_info);
377 spin_lock(&fs_info->tree_mod_seq_lock);
378 if (!elem->seq) {
379 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
380 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
381 }
382 seq = btrfs_inc_tree_mod_seq(fs_info);
383 spin_unlock(&fs_info->tree_mod_seq_lock);
384 tree_mod_log_write_unlock(fs_info);
385
386 return seq;
387 }
388
389 void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
390 struct seq_list *elem)
391 {
392 struct rb_root *tm_root;
393 struct rb_node *node;
394 struct rb_node *next;
395 struct seq_list *cur_elem;
396 struct tree_mod_elem *tm;
397 u64 min_seq = (u64)-1;
398 u64 seq_putting = elem->seq;
399
400 if (!seq_putting)
401 return;
402
403 spin_lock(&fs_info->tree_mod_seq_lock);
404 list_del(&elem->list);
405 elem->seq = 0;
406
407 list_for_each_entry(cur_elem, &fs_info->tree_mod_seq_list, list) {
408 if (cur_elem->seq < min_seq) {
409 if (seq_putting > cur_elem->seq) {
410 /*
411 * blocker with lower sequence number exists, we
412 * cannot remove anything from the log
413 */
414 spin_unlock(&fs_info->tree_mod_seq_lock);
415 return;
416 }
417 min_seq = cur_elem->seq;
418 }
419 }
420 spin_unlock(&fs_info->tree_mod_seq_lock);
421
422 /*
423 * anything that's lower than the lowest existing (read: blocked)
424 * sequence number can be removed from the tree.
425 */
426 tree_mod_log_write_lock(fs_info);
427 tm_root = &fs_info->tree_mod_log;
428 for (node = rb_first(tm_root); node; node = next) {
429 next = rb_next(node);
430 tm = container_of(node, struct tree_mod_elem, node);
431 if (tm->seq > min_seq)
432 continue;
433 rb_erase(node, tm_root);
434 kfree(tm);
435 }
436 tree_mod_log_write_unlock(fs_info);
437 }
438
439 /*
440 * key order of the log:
441 * index -> sequence
442 *
443 * the index is the shifted logical of the *new* root node for root replace
444 * operations, or the shifted logical of the affected block for all other
445 * operations.
446 */
447 static noinline int
448 __tree_mod_log_insert(struct btrfs_fs_info *fs_info, struct tree_mod_elem *tm)
449 {
450 struct rb_root *tm_root;
451 struct rb_node **new;
452 struct rb_node *parent = NULL;
453 struct tree_mod_elem *cur;
454
455 BUG_ON(!tm || !tm->seq);
456
457 tm_root = &fs_info->tree_mod_log;
458 new = &tm_root->rb_node;
459 while (*new) {
460 cur = container_of(*new, struct tree_mod_elem, node);
461 parent = *new;
462 if (cur->index < tm->index)
463 new = &((*new)->rb_left);
464 else if (cur->index > tm->index)
465 new = &((*new)->rb_right);
466 else if (cur->seq < tm->seq)
467 new = &((*new)->rb_left);
468 else if (cur->seq > tm->seq)
469 new = &((*new)->rb_right);
470 else {
471 kfree(tm);
472 return -EEXIST;
473 }
474 }
475
476 rb_link_node(&tm->node, parent, new);
477 rb_insert_color(&tm->node, tm_root);
478 return 0;
479 }
480
481 /*
482 * Determines if logging can be omitted. Returns 1 if it can. Otherwise, it
483 * returns zero with the tree_mod_log_lock acquired. The caller must hold
484 * this until all tree mod log insertions are recorded in the rb tree and then
485 * call tree_mod_log_write_unlock() to release.
486 */
487 static inline int tree_mod_dont_log(struct btrfs_fs_info *fs_info,
488 struct extent_buffer *eb) {
489 smp_mb();
490 if (list_empty(&(fs_info)->tree_mod_seq_list))
491 return 1;
492 if (eb && btrfs_header_level(eb) == 0)
493 return 1;
494
495 tree_mod_log_write_lock(fs_info);
496 if (list_empty(&fs_info->tree_mod_seq_list)) {
497 /*
498 * someone emptied the list while we were waiting for the lock.
499 * we must not add to the list when no blocker exists.
500 */
501 tree_mod_log_write_unlock(fs_info);
502 return 1;
503 }
504
505 return 0;
506 }
507
508 /*
509 * This allocates memory and gets a tree modification sequence number.
510 *
511 * Returns <0 on error.
512 * Returns >0 (the added sequence number) on success.
513 */
514 static inline int tree_mod_alloc(struct btrfs_fs_info *fs_info, gfp_t flags,
515 struct tree_mod_elem **tm_ret)
516 {
517 struct tree_mod_elem *tm;
518
519 /*
520 * once we switch from spin locks to something different, we should
521 * honor the flags parameter here.
522 */
523 tm = *tm_ret = kzalloc(sizeof(*tm), GFP_ATOMIC);
524 if (!tm)
525 return -ENOMEM;
526
527 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
528 return tm->seq;
529 }
530
531 static inline int
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)
535 {
536 int ret;
537 struct tree_mod_elem *tm;
538
539 ret = tree_mod_alloc(fs_info, flags, &tm);
540 if (ret < 0)
541 return ret;
542
543 tm->index = eb->start >> PAGE_CACHE_SHIFT;
544 if (op != MOD_LOG_KEY_ADD) {
545 btrfs_node_key(eb, &tm->key, slot);
546 tm->blockptr = btrfs_node_blockptr(eb, slot);
547 }
548 tm->op = op;
549 tm->slot = slot;
550 tm->generation = btrfs_node_ptr_generation(eb, slot);
551
552 return __tree_mod_log_insert(fs_info, tm);
553 }
554
555 static noinline int
556 tree_mod_log_insert_key_mask(struct btrfs_fs_info *fs_info,
557 struct extent_buffer *eb, int slot,
558 enum mod_log_op op, gfp_t flags)
559 {
560 int ret;
561
562 if (tree_mod_dont_log(fs_info, eb))
563 return 0;
564
565 ret = __tree_mod_log_insert_key(fs_info, eb, slot, op, flags);
566
567 tree_mod_log_write_unlock(fs_info);
568 return ret;
569 }
570
571 static noinline int
572 tree_mod_log_insert_key(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
573 int slot, enum mod_log_op op)
574 {
575 return tree_mod_log_insert_key_mask(fs_info, eb, slot, op, GFP_NOFS);
576 }
577
578 static noinline int
579 tree_mod_log_insert_key_locked(struct btrfs_fs_info *fs_info,
580 struct extent_buffer *eb, int slot,
581 enum mod_log_op op)
582 {
583 return __tree_mod_log_insert_key(fs_info, eb, slot, op, GFP_NOFS);
584 }
585
586 static noinline int
587 tree_mod_log_insert_move(struct btrfs_fs_info *fs_info,
588 struct extent_buffer *eb, int dst_slot, int src_slot,
589 int nr_items, gfp_t flags)
590 {
591 struct tree_mod_elem *tm;
592 int ret;
593 int i;
594
595 if (tree_mod_dont_log(fs_info, eb))
596 return 0;
597
598 /*
599 * When we override something during the move, we log these removals.
600 * This can only happen when we move towards the beginning of the
601 * buffer, i.e. dst_slot < src_slot.
602 */
603 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
604 ret = tree_mod_log_insert_key_locked(fs_info, eb, i + dst_slot,
605 MOD_LOG_KEY_REMOVE_WHILE_MOVING);
606 BUG_ON(ret < 0);
607 }
608
609 ret = tree_mod_alloc(fs_info, flags, &tm);
610 if (ret < 0)
611 goto out;
612
613 tm->index = eb->start >> PAGE_CACHE_SHIFT;
614 tm->slot = src_slot;
615 tm->move.dst_slot = dst_slot;
616 tm->move.nr_items = nr_items;
617 tm->op = MOD_LOG_MOVE_KEYS;
618
619 ret = __tree_mod_log_insert(fs_info, tm);
620 out:
621 tree_mod_log_write_unlock(fs_info);
622 return ret;
623 }
624
625 static inline void
626 __tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
627 {
628 int i;
629 u32 nritems;
630 int ret;
631
632 if (btrfs_header_level(eb) == 0)
633 return;
634
635 nritems = btrfs_header_nritems(eb);
636 for (i = nritems - 1; i >= 0; i--) {
637 ret = tree_mod_log_insert_key_locked(fs_info, eb, i,
638 MOD_LOG_KEY_REMOVE_WHILE_FREEING);
639 BUG_ON(ret < 0);
640 }
641 }
642
643 static noinline int
644 tree_mod_log_insert_root(struct btrfs_fs_info *fs_info,
645 struct extent_buffer *old_root,
646 struct extent_buffer *new_root, gfp_t flags)
647 {
648 struct tree_mod_elem *tm;
649 int ret;
650
651 if (tree_mod_dont_log(fs_info, NULL))
652 return 0;
653
654 ret = tree_mod_alloc(fs_info, flags, &tm);
655 if (ret < 0)
656 goto out;
657
658 tm->index = new_root->start >> PAGE_CACHE_SHIFT;
659 tm->old_root.logical = old_root->start;
660 tm->old_root.level = btrfs_header_level(old_root);
661 tm->generation = btrfs_header_generation(old_root);
662 tm->op = MOD_LOG_ROOT_REPLACE;
663
664 ret = __tree_mod_log_insert(fs_info, tm);
665 out:
666 tree_mod_log_write_unlock(fs_info);
667 return ret;
668 }
669
670 static struct tree_mod_elem *
671 __tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq,
672 int smallest)
673 {
674 struct rb_root *tm_root;
675 struct rb_node *node;
676 struct tree_mod_elem *cur = NULL;
677 struct tree_mod_elem *found = NULL;
678 u64 index = start >> PAGE_CACHE_SHIFT;
679
680 tree_mod_log_read_lock(fs_info);
681 tm_root = &fs_info->tree_mod_log;
682 node = tm_root->rb_node;
683 while (node) {
684 cur = container_of(node, struct tree_mod_elem, node);
685 if (cur->index < index) {
686 node = node->rb_left;
687 } else if (cur->index > index) {
688 node = node->rb_right;
689 } else if (cur->seq < min_seq) {
690 node = node->rb_left;
691 } else if (!smallest) {
692 /* we want the node with the highest seq */
693 if (found)
694 BUG_ON(found->seq > cur->seq);
695 found = cur;
696 node = node->rb_left;
697 } else if (cur->seq > min_seq) {
698 /* we want the node with the smallest seq */
699 if (found)
700 BUG_ON(found->seq < cur->seq);
701 found = cur;
702 node = node->rb_right;
703 } else {
704 found = cur;
705 break;
706 }
707 }
708 tree_mod_log_read_unlock(fs_info);
709
710 return found;
711 }
712
713 /*
714 * this returns the element from the log with the smallest time sequence
715 * value that's in the log (the oldest log item). any element with a time
716 * sequence lower than min_seq will be ignored.
717 */
718 static struct tree_mod_elem *
719 tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info, u64 start,
720 u64 min_seq)
721 {
722 return __tree_mod_log_search(fs_info, start, min_seq, 1);
723 }
724
725 /*
726 * this returns the element from the log with the largest time sequence
727 * value that's in the log (the most recent log item). any element with
728 * a time sequence lower than min_seq will be ignored.
729 */
730 static struct tree_mod_elem *
731 tree_mod_log_search(struct btrfs_fs_info *fs_info, u64 start, u64 min_seq)
732 {
733 return __tree_mod_log_search(fs_info, start, min_seq, 0);
734 }
735
736 static noinline void
737 tree_mod_log_eb_copy(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
738 struct extent_buffer *src, unsigned long dst_offset,
739 unsigned long src_offset, int nr_items)
740 {
741 int ret;
742 int i;
743
744 if (tree_mod_dont_log(fs_info, NULL))
745 return;
746
747 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0) {
748 tree_mod_log_write_unlock(fs_info);
749 return;
750 }
751
752 for (i = 0; i < nr_items; i++) {
753 ret = tree_mod_log_insert_key_locked(fs_info, src,
754 i + src_offset,
755 MOD_LOG_KEY_REMOVE);
756 BUG_ON(ret < 0);
757 ret = tree_mod_log_insert_key_locked(fs_info, dst,
758 i + dst_offset,
759 MOD_LOG_KEY_ADD);
760 BUG_ON(ret < 0);
761 }
762
763 tree_mod_log_write_unlock(fs_info);
764 }
765
766 static inline void
767 tree_mod_log_eb_move(struct btrfs_fs_info *fs_info, struct extent_buffer *dst,
768 int dst_offset, int src_offset, int nr_items)
769 {
770 int ret;
771 ret = tree_mod_log_insert_move(fs_info, dst, dst_offset, src_offset,
772 nr_items, GFP_NOFS);
773 BUG_ON(ret < 0);
774 }
775
776 static noinline void
777 tree_mod_log_set_node_key(struct btrfs_fs_info *fs_info,
778 struct extent_buffer *eb, int slot, int atomic)
779 {
780 int ret;
781
782 ret = tree_mod_log_insert_key_mask(fs_info, eb, slot,
783 MOD_LOG_KEY_REPLACE,
784 atomic ? GFP_ATOMIC : GFP_NOFS);
785 BUG_ON(ret < 0);
786 }
787
788 static noinline void
789 tree_mod_log_free_eb(struct btrfs_fs_info *fs_info, struct extent_buffer *eb)
790 {
791 if (tree_mod_dont_log(fs_info, eb))
792 return;
793
794 __tree_mod_log_free_eb(fs_info, eb);
795
796 tree_mod_log_write_unlock(fs_info);
797 }
798
799 static noinline void
800 tree_mod_log_set_root_pointer(struct btrfs_root *root,
801 struct extent_buffer *new_root_node)
802 {
803 int ret;
804 ret = tree_mod_log_insert_root(root->fs_info, root->node,
805 new_root_node, GFP_NOFS);
806 BUG_ON(ret < 0);
807 }
808
809 /*
810 * check if the tree block can be shared by multiple trees
811 */
812 int btrfs_block_can_be_shared(struct btrfs_root *root,
813 struct extent_buffer *buf)
814 {
815 /*
816 * Tree blocks not in refernece counted trees and tree roots
817 * are never shared. If a block was allocated after the last
818 * snapshot and the block was not allocated by tree relocation,
819 * we know the block is not shared.
820 */
821 if (root->ref_cows &&
822 buf != root->node && buf != root->commit_root &&
823 (btrfs_header_generation(buf) <=
824 btrfs_root_last_snapshot(&root->root_item) ||
825 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)))
826 return 1;
827 #ifdef BTRFS_COMPAT_EXTENT_TREE_V0
828 if (root->ref_cows &&
829 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
830 return 1;
831 #endif
832 return 0;
833 }
834
835 static noinline int update_ref_for_cow(struct btrfs_trans_handle *trans,
836 struct btrfs_root *root,
837 struct extent_buffer *buf,
838 struct extent_buffer *cow,
839 int *last_ref)
840 {
841 u64 refs;
842 u64 owner;
843 u64 flags;
844 u64 new_flags = 0;
845 int ret;
846
847 /*
848 * Backrefs update rules:
849 *
850 * Always use full backrefs for extent pointers in tree block
851 * allocated by tree relocation.
852 *
853 * If a shared tree block is no longer referenced by its owner
854 * tree (btrfs_header_owner(buf) == root->root_key.objectid),
855 * use full backrefs for extent pointers in tree block.
856 *
857 * If a tree block is been relocating
858 * (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID),
859 * use full backrefs for extent pointers in tree block.
860 * The reason for this is some operations (such as drop tree)
861 * are only allowed for blocks use full backrefs.
862 */
863
864 if (btrfs_block_can_be_shared(root, buf)) {
865 ret = btrfs_lookup_extent_info(trans, root, buf->start,
866 buf->len, &refs, &flags);
867 if (ret)
868 return ret;
869 if (refs == 0) {
870 ret = -EROFS;
871 btrfs_std_error(root->fs_info, ret);
872 return ret;
873 }
874 } else {
875 refs = 1;
876 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
877 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
878 flags = BTRFS_BLOCK_FLAG_FULL_BACKREF;
879 else
880 flags = 0;
881 }
882
883 owner = btrfs_header_owner(buf);
884 BUG_ON(owner == BTRFS_TREE_RELOC_OBJECTID &&
885 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF));
886
887 if (refs > 1) {
888 if ((owner == root->root_key.objectid ||
889 root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) &&
890 !(flags & BTRFS_BLOCK_FLAG_FULL_BACKREF)) {
891 ret = btrfs_inc_ref(trans, root, buf, 1, 1);
892 BUG_ON(ret); /* -ENOMEM */
893
894 if (root->root_key.objectid ==
895 BTRFS_TREE_RELOC_OBJECTID) {
896 ret = btrfs_dec_ref(trans, root, buf, 0, 1);
897 BUG_ON(ret); /* -ENOMEM */
898 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
899 BUG_ON(ret); /* -ENOMEM */
900 }
901 new_flags |= BTRFS_BLOCK_FLAG_FULL_BACKREF;
902 } else {
903
904 if (root->root_key.objectid ==
905 BTRFS_TREE_RELOC_OBJECTID)
906 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
907 else
908 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
909 BUG_ON(ret); /* -ENOMEM */
910 }
911 if (new_flags != 0) {
912 ret = btrfs_set_disk_extent_flags(trans, root,
913 buf->start,
914 buf->len,
915 new_flags, 0);
916 if (ret)
917 return ret;
918 }
919 } else {
920 if (flags & BTRFS_BLOCK_FLAG_FULL_BACKREF) {
921 if (root->root_key.objectid ==
922 BTRFS_TREE_RELOC_OBJECTID)
923 ret = btrfs_inc_ref(trans, root, cow, 1, 1);
924 else
925 ret = btrfs_inc_ref(trans, root, cow, 0, 1);
926 BUG_ON(ret); /* -ENOMEM */
927 ret = btrfs_dec_ref(trans, root, buf, 1, 1);
928 BUG_ON(ret); /* -ENOMEM */
929 }
930 tree_mod_log_free_eb(root->fs_info, buf);
931 clean_tree_block(trans, root, buf);
932 *last_ref = 1;
933 }
934 return 0;
935 }
936
937 /*
938 * does the dirty work in cow of a single block. The parent block (if
939 * supplied) is updated to point to the new cow copy. The new buffer is marked
940 * dirty and returned locked. If you modify the block it needs to be marked
941 * dirty again.
942 *
943 * search_start -- an allocation hint for the new block
944 *
945 * empty_size -- a hint that you plan on doing more cow. This is the size in
946 * bytes the allocator should try to find free next to the block it returns.
947 * This is just a hint and may be ignored by the allocator.
948 */
949 static noinline int __btrfs_cow_block(struct btrfs_trans_handle *trans,
950 struct btrfs_root *root,
951 struct extent_buffer *buf,
952 struct extent_buffer *parent, int parent_slot,
953 struct extent_buffer **cow_ret,
954 u64 search_start, u64 empty_size)
955 {
956 struct btrfs_disk_key disk_key;
957 struct extent_buffer *cow;
958 int level, ret;
959 int last_ref = 0;
960 int unlock_orig = 0;
961 u64 parent_start;
962
963 if (*cow_ret == buf)
964 unlock_orig = 1;
965
966 btrfs_assert_tree_locked(buf);
967
968 WARN_ON(root->ref_cows && trans->transid !=
969 root->fs_info->running_transaction->transid);
970 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
971
972 level = btrfs_header_level(buf);
973
974 if (level == 0)
975 btrfs_item_key(buf, &disk_key, 0);
976 else
977 btrfs_node_key(buf, &disk_key, 0);
978
979 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
980 if (parent)
981 parent_start = parent->start;
982 else
983 parent_start = 0;
984 } else
985 parent_start = 0;
986
987 cow = btrfs_alloc_free_block(trans, root, buf->len, parent_start,
988 root->root_key.objectid, &disk_key,
989 level, search_start, empty_size);
990 if (IS_ERR(cow))
991 return PTR_ERR(cow);
992
993 /* cow is set to blocking by btrfs_init_new_buffer */
994
995 copy_extent_buffer(cow, buf, 0, 0, cow->len);
996 btrfs_set_header_bytenr(cow, cow->start);
997 btrfs_set_header_generation(cow, trans->transid);
998 btrfs_set_header_backref_rev(cow, BTRFS_MIXED_BACKREF_REV);
999 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN |
1000 BTRFS_HEADER_FLAG_RELOC);
1001 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1002 btrfs_set_header_flag(cow, BTRFS_HEADER_FLAG_RELOC);
1003 else
1004 btrfs_set_header_owner(cow, root->root_key.objectid);
1005
1006 write_extent_buffer(cow, root->fs_info->fsid,
1007 (unsigned long)btrfs_header_fsid(cow),
1008 BTRFS_FSID_SIZE);
1009
1010 ret = update_ref_for_cow(trans, root, buf, cow, &last_ref);
1011 if (ret) {
1012 btrfs_abort_transaction(trans, root, ret);
1013 return ret;
1014 }
1015
1016 if (root->ref_cows)
1017 btrfs_reloc_cow_block(trans, root, buf, cow);
1018
1019 if (buf == root->node) {
1020 WARN_ON(parent && parent != buf);
1021 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
1022 btrfs_header_backref_rev(buf) < BTRFS_MIXED_BACKREF_REV)
1023 parent_start = buf->start;
1024 else
1025 parent_start = 0;
1026
1027 extent_buffer_get(cow);
1028 tree_mod_log_set_root_pointer(root, cow);
1029 rcu_assign_pointer(root->node, cow);
1030
1031 btrfs_free_tree_block(trans, root, buf, parent_start,
1032 last_ref);
1033 free_extent_buffer(buf);
1034 add_root_to_dirty_list(root);
1035 } else {
1036 if (root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
1037 parent_start = parent->start;
1038 else
1039 parent_start = 0;
1040
1041 WARN_ON(trans->transid != btrfs_header_generation(parent));
1042 tree_mod_log_insert_key(root->fs_info, parent, parent_slot,
1043 MOD_LOG_KEY_REPLACE);
1044 btrfs_set_node_blockptr(parent, parent_slot,
1045 cow->start);
1046 btrfs_set_node_ptr_generation(parent, parent_slot,
1047 trans->transid);
1048 btrfs_mark_buffer_dirty(parent);
1049 btrfs_free_tree_block(trans, root, buf, parent_start,
1050 last_ref);
1051 }
1052 if (unlock_orig)
1053 btrfs_tree_unlock(buf);
1054 free_extent_buffer_stale(buf);
1055 btrfs_mark_buffer_dirty(cow);
1056 *cow_ret = cow;
1057 return 0;
1058 }
1059
1060 /*
1061 * returns the logical address of the oldest predecessor of the given root.
1062 * entries older than time_seq are ignored.
1063 */
1064 static struct tree_mod_elem *
1065 __tree_mod_log_oldest_root(struct btrfs_fs_info *fs_info,
1066 struct btrfs_root *root, u64 time_seq)
1067 {
1068 struct tree_mod_elem *tm;
1069 struct tree_mod_elem *found = NULL;
1070 u64 root_logical = root->node->start;
1071 int looped = 0;
1072
1073 if (!time_seq)
1074 return 0;
1075
1076 /*
1077 * the very last operation that's logged for a root is the replacement
1078 * operation (if it is replaced at all). this has the index of the *new*
1079 * root, making it the very first operation that's logged for this root.
1080 */
1081 while (1) {
1082 tm = tree_mod_log_search_oldest(fs_info, root_logical,
1083 time_seq);
1084 if (!looped && !tm)
1085 return 0;
1086 /*
1087 * if there are no tree operation for the oldest root, we simply
1088 * return it. this should only happen if that (old) root is at
1089 * level 0.
1090 */
1091 if (!tm)
1092 break;
1093
1094 /*
1095 * if there's an operation that's not a root replacement, we
1096 * found the oldest version of our root. normally, we'll find a
1097 * MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
1098 */
1099 if (tm->op != MOD_LOG_ROOT_REPLACE)
1100 break;
1101
1102 found = tm;
1103 root_logical = tm->old_root.logical;
1104 BUG_ON(root_logical == root->node->start);
1105 looped = 1;
1106 }
1107
1108 /* if there's no old root to return, return what we found instead */
1109 if (!found)
1110 found = tm;
1111
1112 return found;
1113 }
1114
1115 /*
1116 * tm is a pointer to the first operation to rewind within eb. then, all
1117 * previous operations will be rewinded (until we reach something older than
1118 * time_seq).
1119 */
1120 static void
1121 __tree_mod_log_rewind(struct extent_buffer *eb, u64 time_seq,
1122 struct tree_mod_elem *first_tm)
1123 {
1124 u32 n;
1125 struct rb_node *next;
1126 struct tree_mod_elem *tm = first_tm;
1127 unsigned long o_dst;
1128 unsigned long o_src;
1129 unsigned long p_size = sizeof(struct btrfs_key_ptr);
1130
1131 n = btrfs_header_nritems(eb);
1132 while (tm && tm->seq >= time_seq) {
1133 /*
1134 * all the operations are recorded with the operator used for
1135 * the modification. as we're going backwards, we do the
1136 * opposite of each operation here.
1137 */
1138 switch (tm->op) {
1139 case MOD_LOG_KEY_REMOVE_WHILE_FREEING:
1140 BUG_ON(tm->slot < n);
1141 case MOD_LOG_KEY_REMOVE:
1142 n++;
1143 case MOD_LOG_KEY_REMOVE_WHILE_MOVING:
1144 btrfs_set_node_key(eb, &tm->key, tm->slot);
1145 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1146 btrfs_set_node_ptr_generation(eb, tm->slot,
1147 tm->generation);
1148 break;
1149 case MOD_LOG_KEY_REPLACE:
1150 BUG_ON(tm->slot >= n);
1151 btrfs_set_node_key(eb, &tm->key, tm->slot);
1152 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
1153 btrfs_set_node_ptr_generation(eb, tm->slot,
1154 tm->generation);
1155 break;
1156 case MOD_LOG_KEY_ADD:
1157 /* if a move operation is needed it's in the log */
1158 n--;
1159 break;
1160 case MOD_LOG_MOVE_KEYS:
1161 o_dst = btrfs_node_key_ptr_offset(tm->slot);
1162 o_src = btrfs_node_key_ptr_offset(tm->move.dst_slot);
1163 memmove_extent_buffer(eb, o_dst, o_src,
1164 tm->move.nr_items * p_size);
1165 break;
1166 case MOD_LOG_ROOT_REPLACE:
1167 /*
1168 * this operation is special. for roots, this must be
1169 * handled explicitly before rewinding.
1170 * for non-roots, this operation may exist if the node
1171 * was a root: root A -> child B; then A gets empty and
1172 * B is promoted to the new root. in the mod log, we'll
1173 * have a root-replace operation for B, a tree block
1174 * that is no root. we simply ignore that operation.
1175 */
1176 break;
1177 }
1178 next = rb_next(&tm->node);
1179 if (!next)
1180 break;
1181 tm = container_of(next, struct tree_mod_elem, node);
1182 if (tm->index != first_tm->index)
1183 break;
1184 }
1185 btrfs_set_header_nritems(eb, n);
1186 }
1187
1188 static struct extent_buffer *
1189 tree_mod_log_rewind(struct btrfs_fs_info *fs_info, struct extent_buffer *eb,
1190 u64 time_seq)
1191 {
1192 struct extent_buffer *eb_rewin;
1193 struct tree_mod_elem *tm;
1194
1195 if (!time_seq)
1196 return eb;
1197
1198 if (btrfs_header_level(eb) == 0)
1199 return eb;
1200
1201 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
1202 if (!tm)
1203 return eb;
1204
1205 if (tm->op == MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1206 BUG_ON(tm->slot != 0);
1207 eb_rewin = alloc_dummy_extent_buffer(eb->start,
1208 fs_info->tree_root->nodesize);
1209 BUG_ON(!eb_rewin);
1210 btrfs_set_header_bytenr(eb_rewin, eb->start);
1211 btrfs_set_header_backref_rev(eb_rewin,
1212 btrfs_header_backref_rev(eb));
1213 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
1214 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
1215 } else {
1216 eb_rewin = btrfs_clone_extent_buffer(eb);
1217 BUG_ON(!eb_rewin);
1218 }
1219
1220 extent_buffer_get(eb_rewin);
1221 free_extent_buffer(eb);
1222
1223 __tree_mod_log_rewind(eb_rewin, time_seq, tm);
1224 WARN_ON(btrfs_header_nritems(eb_rewin) >
1225 BTRFS_NODEPTRS_PER_BLOCK(fs_info->fs_root));
1226
1227 return eb_rewin;
1228 }
1229
1230 /*
1231 * get_old_root() rewinds the state of @root's root node to the given @time_seq
1232 * value. If there are no changes, the current root->root_node is returned. If
1233 * anything changed in between, there's a fresh buffer allocated on which the
1234 * rewind operations are done. In any case, the returned buffer is read locked.
1235 * Returns NULL on error (with no locks held).
1236 */
1237 static inline struct extent_buffer *
1238 get_old_root(struct btrfs_root *root, u64 time_seq)
1239 {
1240 struct tree_mod_elem *tm;
1241 struct extent_buffer *eb;
1242 struct extent_buffer *old;
1243 struct tree_mod_root *old_root = NULL;
1244 u64 old_generation = 0;
1245 u64 logical;
1246 u32 blocksize;
1247
1248 eb = btrfs_read_lock_root_node(root);
1249 tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
1250 if (!tm)
1251 return root->node;
1252
1253 if (tm->op == MOD_LOG_ROOT_REPLACE) {
1254 old_root = &tm->old_root;
1255 old_generation = tm->generation;
1256 logical = old_root->logical;
1257 } else {
1258 logical = root->node->start;
1259 }
1260
1261 tm = tree_mod_log_search(root->fs_info, logical, time_seq);
1262 if (old_root && tm && tm->op != MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1263 btrfs_tree_read_unlock(root->node);
1264 free_extent_buffer(root->node);
1265 blocksize = btrfs_level_size(root, old_root->level);
1266 old = read_tree_block(root, logical, blocksize, 0);
1267 if (!old) {
1268 pr_warn("btrfs: failed to read tree block %llu from get_old_root\n",
1269 logical);
1270 WARN_ON(1);
1271 } else {
1272 eb = btrfs_clone_extent_buffer(old);
1273 free_extent_buffer(old);
1274 }
1275 } else if (old_root) {
1276 btrfs_tree_read_unlock(root->node);
1277 free_extent_buffer(root->node);
1278 eb = alloc_dummy_extent_buffer(logical, root->nodesize);
1279 } else {
1280 eb = btrfs_clone_extent_buffer(root->node);
1281 btrfs_tree_read_unlock(root->node);
1282 free_extent_buffer(root->node);
1283 }
1284
1285 if (!eb)
1286 return NULL;
1287 extent_buffer_get(eb);
1288 btrfs_tree_read_lock(eb);
1289 if (old_root) {
1290 btrfs_set_header_bytenr(eb, eb->start);
1291 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1292 btrfs_set_header_owner(eb, root->root_key.objectid);
1293 btrfs_set_header_level(eb, old_root->level);
1294 btrfs_set_header_generation(eb, old_generation);
1295 }
1296 if (tm)
1297 __tree_mod_log_rewind(eb, time_seq, tm);
1298 else
1299 WARN_ON(btrfs_header_level(eb) != 0);
1300 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(root));
1301
1302 return eb;
1303 }
1304
1305 int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1306 {
1307 struct tree_mod_elem *tm;
1308 int level;
1309
1310 tm = __tree_mod_log_oldest_root(root->fs_info, root, time_seq);
1311 if (tm && tm->op == MOD_LOG_ROOT_REPLACE) {
1312 level = tm->old_root.level;
1313 } else {
1314 rcu_read_lock();
1315 level = btrfs_header_level(root->node);
1316 rcu_read_unlock();
1317 }
1318
1319 return level;
1320 }
1321
1322 static inline int should_cow_block(struct btrfs_trans_handle *trans,
1323 struct btrfs_root *root,
1324 struct extent_buffer *buf)
1325 {
1326 /* ensure we can see the force_cow */
1327 smp_rmb();
1328
1329 /*
1330 * We do not need to cow a block if
1331 * 1) this block is not created or changed in this transaction;
1332 * 2) this block does not belong to TREE_RELOC tree;
1333 * 3) the root is not forced COW.
1334 *
1335 * What is forced COW:
1336 * when we create snapshot during commiting the transaction,
1337 * after we've finished coping src root, we must COW the shared
1338 * block to ensure the metadata consistency.
1339 */
1340 if (btrfs_header_generation(buf) == trans->transid &&
1341 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN) &&
1342 !(root->root_key.objectid != BTRFS_TREE_RELOC_OBJECTID &&
1343 btrfs_header_flag(buf, BTRFS_HEADER_FLAG_RELOC)) &&
1344 !root->force_cow)
1345 return 0;
1346 return 1;
1347 }
1348
1349 /*
1350 * cows a single block, see __btrfs_cow_block for the real work.
1351 * This version of it has extra checks so that a block isn't cow'd more than
1352 * once per transaction, as long as it hasn't been written yet
1353 */
1354 noinline int btrfs_cow_block(struct btrfs_trans_handle *trans,
1355 struct btrfs_root *root, struct extent_buffer *buf,
1356 struct extent_buffer *parent, int parent_slot,
1357 struct extent_buffer **cow_ret)
1358 {
1359 u64 search_start;
1360 int ret;
1361
1362 if (trans->transaction != root->fs_info->running_transaction)
1363 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1364 (unsigned long long)trans->transid,
1365 (unsigned long long)
1366 root->fs_info->running_transaction->transid);
1367
1368 if (trans->transid != root->fs_info->generation)
1369 WARN(1, KERN_CRIT "trans %llu running %llu\n",
1370 (unsigned long long)trans->transid,
1371 (unsigned long long)root->fs_info->generation);
1372
1373 if (!should_cow_block(trans, root, buf)) {
1374 *cow_ret = buf;
1375 return 0;
1376 }
1377
1378 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
1379
1380 if (parent)
1381 btrfs_set_lock_blocking(parent);
1382 btrfs_set_lock_blocking(buf);
1383
1384 ret = __btrfs_cow_block(trans, root, buf, parent,
1385 parent_slot, cow_ret, search_start, 0);
1386
1387 trace_btrfs_cow_block(root, buf, *cow_ret);
1388
1389 return ret;
1390 }
1391
1392 /*
1393 * helper function for defrag to decide if two blocks pointed to by a
1394 * node are actually close by
1395 */
1396 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
1397 {
1398 if (blocknr < other && other - (blocknr + blocksize) < 32768)
1399 return 1;
1400 if (blocknr > other && blocknr - (other + blocksize) < 32768)
1401 return 1;
1402 return 0;
1403 }
1404
1405 /*
1406 * compare two keys in a memcmp fashion
1407 */
1408 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
1409 {
1410 struct btrfs_key k1;
1411
1412 btrfs_disk_key_to_cpu(&k1, disk);
1413
1414 return btrfs_comp_cpu_keys(&k1, k2);
1415 }
1416
1417 /*
1418 * same as comp_keys only with two btrfs_key's
1419 */
1420 int btrfs_comp_cpu_keys(struct btrfs_key *k1, struct btrfs_key *k2)
1421 {
1422 if (k1->objectid > k2->objectid)
1423 return 1;
1424 if (k1->objectid < k2->objectid)
1425 return -1;
1426 if (k1->type > k2->type)
1427 return 1;
1428 if (k1->type < k2->type)
1429 return -1;
1430 if (k1->offset > k2->offset)
1431 return 1;
1432 if (k1->offset < k2->offset)
1433 return -1;
1434 return 0;
1435 }
1436
1437 /*
1438 * this is used by the defrag code to go through all the
1439 * leaves pointed to by a node and reallocate them so that
1440 * disk order is close to key order
1441 */
1442 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
1443 struct btrfs_root *root, struct extent_buffer *parent,
1444 int start_slot, int cache_only, u64 *last_ret,
1445 struct btrfs_key *progress)
1446 {
1447 struct extent_buffer *cur;
1448 u64 blocknr;
1449 u64 gen;
1450 u64 search_start = *last_ret;
1451 u64 last_block = 0;
1452 u64 other;
1453 u32 parent_nritems;
1454 int end_slot;
1455 int i;
1456 int err = 0;
1457 int parent_level;
1458 int uptodate;
1459 u32 blocksize;
1460 int progress_passed = 0;
1461 struct btrfs_disk_key disk_key;
1462
1463 parent_level = btrfs_header_level(parent);
1464 if (cache_only && parent_level != 1)
1465 return 0;
1466
1467 WARN_ON(trans->transaction != root->fs_info->running_transaction);
1468 WARN_ON(trans->transid != root->fs_info->generation);
1469
1470 parent_nritems = btrfs_header_nritems(parent);
1471 blocksize = btrfs_level_size(root, parent_level - 1);
1472 end_slot = parent_nritems;
1473
1474 if (parent_nritems == 1)
1475 return 0;
1476
1477 btrfs_set_lock_blocking(parent);
1478
1479 for (i = start_slot; i < end_slot; i++) {
1480 int close = 1;
1481
1482 btrfs_node_key(parent, &disk_key, i);
1483 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
1484 continue;
1485
1486 progress_passed = 1;
1487 blocknr = btrfs_node_blockptr(parent, i);
1488 gen = btrfs_node_ptr_generation(parent, i);
1489 if (last_block == 0)
1490 last_block = blocknr;
1491
1492 if (i > 0) {
1493 other = btrfs_node_blockptr(parent, i - 1);
1494 close = close_blocks(blocknr, other, blocksize);
1495 }
1496 if (!close && i < end_slot - 2) {
1497 other = btrfs_node_blockptr(parent, i + 1);
1498 close = close_blocks(blocknr, other, blocksize);
1499 }
1500 if (close) {
1501 last_block = blocknr;
1502 continue;
1503 }
1504
1505 cur = btrfs_find_tree_block(root, blocknr, blocksize);
1506 if (cur)
1507 uptodate = btrfs_buffer_uptodate(cur, gen, 0);
1508 else
1509 uptodate = 0;
1510 if (!cur || !uptodate) {
1511 if (cache_only) {
1512 free_extent_buffer(cur);
1513 continue;
1514 }
1515 if (!cur) {
1516 cur = read_tree_block(root, blocknr,
1517 blocksize, gen);
1518 if (!cur)
1519 return -EIO;
1520 } else if (!uptodate) {
1521 err = btrfs_read_buffer(cur, gen);
1522 if (err) {
1523 free_extent_buffer(cur);
1524 return err;
1525 }
1526 }
1527 }
1528 if (search_start == 0)
1529 search_start = last_block;
1530
1531 btrfs_tree_lock(cur);
1532 btrfs_set_lock_blocking(cur);
1533 err = __btrfs_cow_block(trans, root, cur, parent, i,
1534 &cur, search_start,
1535 min(16 * blocksize,
1536 (end_slot - i) * blocksize));
1537 if (err) {
1538 btrfs_tree_unlock(cur);
1539 free_extent_buffer(cur);
1540 break;
1541 }
1542 search_start = cur->start;
1543 last_block = cur->start;
1544 *last_ret = search_start;
1545 btrfs_tree_unlock(cur);
1546 free_extent_buffer(cur);
1547 }
1548 return err;
1549 }
1550
1551 /*
1552 * The leaf data grows from end-to-front in the node.
1553 * this returns the address of the start of the last item,
1554 * which is the stop of the leaf data stack
1555 */
1556 static inline unsigned int leaf_data_end(struct btrfs_root *root,
1557 struct extent_buffer *leaf)
1558 {
1559 u32 nr = btrfs_header_nritems(leaf);
1560 if (nr == 0)
1561 return BTRFS_LEAF_DATA_SIZE(root);
1562 return btrfs_item_offset_nr(leaf, nr - 1);
1563 }
1564
1565
1566 /*
1567 * search for key in the extent_buffer. The items start at offset p,
1568 * and they are item_size apart. There are 'max' items in p.
1569 *
1570 * the slot in the array is returned via slot, and it points to
1571 * the place where you would insert key if it is not found in
1572 * the array.
1573 *
1574 * slot may point to max if the key is bigger than all of the keys
1575 */
1576 static noinline int generic_bin_search(struct extent_buffer *eb,
1577 unsigned long p,
1578 int item_size, struct btrfs_key *key,
1579 int max, int *slot)
1580 {
1581 int low = 0;
1582 int high = max;
1583 int mid;
1584 int ret;
1585 struct btrfs_disk_key *tmp = NULL;
1586 struct btrfs_disk_key unaligned;
1587 unsigned long offset;
1588 char *kaddr = NULL;
1589 unsigned long map_start = 0;
1590 unsigned long map_len = 0;
1591 int err;
1592
1593 while (low < high) {
1594 mid = (low + high) / 2;
1595 offset = p + mid * item_size;
1596
1597 if (!kaddr || offset < map_start ||
1598 (offset + sizeof(struct btrfs_disk_key)) >
1599 map_start + map_len) {
1600
1601 err = map_private_extent_buffer(eb, offset,
1602 sizeof(struct btrfs_disk_key),
1603 &kaddr, &map_start, &map_len);
1604
1605 if (!err) {
1606 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1607 map_start);
1608 } else {
1609 read_extent_buffer(eb, &unaligned,
1610 offset, sizeof(unaligned));
1611 tmp = &unaligned;
1612 }
1613
1614 } else {
1615 tmp = (struct btrfs_disk_key *)(kaddr + offset -
1616 map_start);
1617 }
1618 ret = comp_keys(tmp, key);
1619
1620 if (ret < 0)
1621 low = mid + 1;
1622 else if (ret > 0)
1623 high = mid;
1624 else {
1625 *slot = mid;
1626 return 0;
1627 }
1628 }
1629 *slot = low;
1630 return 1;
1631 }
1632
1633 /*
1634 * simple bin_search frontend that does the right thing for
1635 * leaves vs nodes
1636 */
1637 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1638 int level, int *slot)
1639 {
1640 if (level == 0)
1641 return generic_bin_search(eb,
1642 offsetof(struct btrfs_leaf, items),
1643 sizeof(struct btrfs_item),
1644 key, btrfs_header_nritems(eb),
1645 slot);
1646 else
1647 return generic_bin_search(eb,
1648 offsetof(struct btrfs_node, ptrs),
1649 sizeof(struct btrfs_key_ptr),
1650 key, btrfs_header_nritems(eb),
1651 slot);
1652 }
1653
1654 int btrfs_bin_search(struct extent_buffer *eb, struct btrfs_key *key,
1655 int level, int *slot)
1656 {
1657 return bin_search(eb, key, level, slot);
1658 }
1659
1660 static void root_add_used(struct btrfs_root *root, u32 size)
1661 {
1662 spin_lock(&root->accounting_lock);
1663 btrfs_set_root_used(&root->root_item,
1664 btrfs_root_used(&root->root_item) + size);
1665 spin_unlock(&root->accounting_lock);
1666 }
1667
1668 static void root_sub_used(struct btrfs_root *root, u32 size)
1669 {
1670 spin_lock(&root->accounting_lock);
1671 btrfs_set_root_used(&root->root_item,
1672 btrfs_root_used(&root->root_item) - size);
1673 spin_unlock(&root->accounting_lock);
1674 }
1675
1676 /* given a node and slot number, this reads the blocks it points to. The
1677 * extent buffer is returned with a reference taken (but unlocked).
1678 * NULL is returned on error.
1679 */
1680 static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root,
1681 struct extent_buffer *parent, int slot)
1682 {
1683 int level = btrfs_header_level(parent);
1684 if (slot < 0)
1685 return NULL;
1686 if (slot >= btrfs_header_nritems(parent))
1687 return NULL;
1688
1689 BUG_ON(level == 0);
1690
1691 return read_tree_block(root, btrfs_node_blockptr(parent, slot),
1692 btrfs_level_size(root, level - 1),
1693 btrfs_node_ptr_generation(parent, slot));
1694 }
1695
1696 /*
1697 * node level balancing, used to make sure nodes are in proper order for
1698 * item deletion. We balance from the top down, so we have to make sure
1699 * that a deletion won't leave an node completely empty later on.
1700 */
1701 static noinline int balance_level(struct btrfs_trans_handle *trans,
1702 struct btrfs_root *root,
1703 struct btrfs_path *path, int level)
1704 {
1705 struct extent_buffer *right = NULL;
1706 struct extent_buffer *mid;
1707 struct extent_buffer *left = NULL;
1708 struct extent_buffer *parent = NULL;
1709 int ret = 0;
1710 int wret;
1711 int pslot;
1712 int orig_slot = path->slots[level];
1713 u64 orig_ptr;
1714
1715 if (level == 0)
1716 return 0;
1717
1718 mid = path->nodes[level];
1719
1720 WARN_ON(path->locks[level] != BTRFS_WRITE_LOCK &&
1721 path->locks[level] != BTRFS_WRITE_LOCK_BLOCKING);
1722 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1723
1724 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
1725
1726 if (level < BTRFS_MAX_LEVEL - 1) {
1727 parent = path->nodes[level + 1];
1728 pslot = path->slots[level + 1];
1729 }
1730
1731 /*
1732 * deal with the case where there is only one pointer in the root
1733 * by promoting the node below to a root
1734 */
1735 if (!parent) {
1736 struct extent_buffer *child;
1737
1738 if (btrfs_header_nritems(mid) != 1)
1739 return 0;
1740
1741 /* promote the child to a root */
1742 child = read_node_slot(root, mid, 0);
1743 if (!child) {
1744 ret = -EROFS;
1745 btrfs_std_error(root->fs_info, ret);
1746 goto enospc;
1747 }
1748
1749 btrfs_tree_lock(child);
1750 btrfs_set_lock_blocking(child);
1751 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
1752 if (ret) {
1753 btrfs_tree_unlock(child);
1754 free_extent_buffer(child);
1755 goto enospc;
1756 }
1757
1758 tree_mod_log_free_eb(root->fs_info, root->node);
1759 tree_mod_log_set_root_pointer(root, child);
1760 rcu_assign_pointer(root->node, child);
1761
1762 add_root_to_dirty_list(root);
1763 btrfs_tree_unlock(child);
1764
1765 path->locks[level] = 0;
1766 path->nodes[level] = NULL;
1767 clean_tree_block(trans, root, mid);
1768 btrfs_tree_unlock(mid);
1769 /* once for the path */
1770 free_extent_buffer(mid);
1771
1772 root_sub_used(root, mid->len);
1773 btrfs_free_tree_block(trans, root, mid, 0, 1);
1774 /* once for the root ptr */
1775 free_extent_buffer_stale(mid);
1776 return 0;
1777 }
1778 if (btrfs_header_nritems(mid) >
1779 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
1780 return 0;
1781
1782 left = read_node_slot(root, parent, pslot - 1);
1783 if (left) {
1784 btrfs_tree_lock(left);
1785 btrfs_set_lock_blocking(left);
1786 wret = btrfs_cow_block(trans, root, left,
1787 parent, pslot - 1, &left);
1788 if (wret) {
1789 ret = wret;
1790 goto enospc;
1791 }
1792 }
1793 right = read_node_slot(root, parent, pslot + 1);
1794 if (right) {
1795 btrfs_tree_lock(right);
1796 btrfs_set_lock_blocking(right);
1797 wret = btrfs_cow_block(trans, root, right,
1798 parent, pslot + 1, &right);
1799 if (wret) {
1800 ret = wret;
1801 goto enospc;
1802 }
1803 }
1804
1805 /* first, try to make some room in the middle buffer */
1806 if (left) {
1807 orig_slot += btrfs_header_nritems(left);
1808 wret = push_node_left(trans, root, left, mid, 1);
1809 if (wret < 0)
1810 ret = wret;
1811 }
1812
1813 /*
1814 * then try to empty the right most buffer into the middle
1815 */
1816 if (right) {
1817 wret = push_node_left(trans, root, mid, right, 1);
1818 if (wret < 0 && wret != -ENOSPC)
1819 ret = wret;
1820 if (btrfs_header_nritems(right) == 0) {
1821 clean_tree_block(trans, root, right);
1822 btrfs_tree_unlock(right);
1823 del_ptr(trans, root, path, level + 1, pslot + 1);
1824 root_sub_used(root, right->len);
1825 btrfs_free_tree_block(trans, root, right, 0, 1);
1826 free_extent_buffer_stale(right);
1827 right = NULL;
1828 } else {
1829 struct btrfs_disk_key right_key;
1830 btrfs_node_key(right, &right_key, 0);
1831 tree_mod_log_set_node_key(root->fs_info, parent,
1832 pslot + 1, 0);
1833 btrfs_set_node_key(parent, &right_key, pslot + 1);
1834 btrfs_mark_buffer_dirty(parent);
1835 }
1836 }
1837 if (btrfs_header_nritems(mid) == 1) {
1838 /*
1839 * we're not allowed to leave a node with one item in the
1840 * tree during a delete. A deletion from lower in the tree
1841 * could try to delete the only pointer in this node.
1842 * So, pull some keys from the left.
1843 * There has to be a left pointer at this point because
1844 * otherwise we would have pulled some pointers from the
1845 * right
1846 */
1847 if (!left) {
1848 ret = -EROFS;
1849 btrfs_std_error(root->fs_info, ret);
1850 goto enospc;
1851 }
1852 wret = balance_node_right(trans, root, mid, left);
1853 if (wret < 0) {
1854 ret = wret;
1855 goto enospc;
1856 }
1857 if (wret == 1) {
1858 wret = push_node_left(trans, root, left, mid, 1);
1859 if (wret < 0)
1860 ret = wret;
1861 }
1862 BUG_ON(wret == 1);
1863 }
1864 if (btrfs_header_nritems(mid) == 0) {
1865 clean_tree_block(trans, root, mid);
1866 btrfs_tree_unlock(mid);
1867 del_ptr(trans, root, path, level + 1, pslot);
1868 root_sub_used(root, mid->len);
1869 btrfs_free_tree_block(trans, root, mid, 0, 1);
1870 free_extent_buffer_stale(mid);
1871 mid = NULL;
1872 } else {
1873 /* update the parent key to reflect our changes */
1874 struct btrfs_disk_key mid_key;
1875 btrfs_node_key(mid, &mid_key, 0);
1876 tree_mod_log_set_node_key(root->fs_info, parent,
1877 pslot, 0);
1878 btrfs_set_node_key(parent, &mid_key, pslot);
1879 btrfs_mark_buffer_dirty(parent);
1880 }
1881
1882 /* update the path */
1883 if (left) {
1884 if (btrfs_header_nritems(left) > orig_slot) {
1885 extent_buffer_get(left);
1886 /* left was locked after cow */
1887 path->nodes[level] = left;
1888 path->slots[level + 1] -= 1;
1889 path->slots[level] = orig_slot;
1890 if (mid) {
1891 btrfs_tree_unlock(mid);
1892 free_extent_buffer(mid);
1893 }
1894 } else {
1895 orig_slot -= btrfs_header_nritems(left);
1896 path->slots[level] = orig_slot;
1897 }
1898 }
1899 /* double check we haven't messed things up */
1900 if (orig_ptr !=
1901 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
1902 BUG();
1903 enospc:
1904 if (right) {
1905 btrfs_tree_unlock(right);
1906 free_extent_buffer(right);
1907 }
1908 if (left) {
1909 if (path->nodes[level] != left)
1910 btrfs_tree_unlock(left);
1911 free_extent_buffer(left);
1912 }
1913 return ret;
1914 }
1915
1916 /* Node balancing for insertion. Here we only split or push nodes around
1917 * when they are completely full. This is also done top down, so we
1918 * have to be pessimistic.
1919 */
1920 static noinline int push_nodes_for_insert(struct btrfs_trans_handle *trans,
1921 struct btrfs_root *root,
1922 struct btrfs_path *path, int level)
1923 {
1924 struct extent_buffer *right = NULL;
1925 struct extent_buffer *mid;
1926 struct extent_buffer *left = NULL;
1927 struct extent_buffer *parent = NULL;
1928 int ret = 0;
1929 int wret;
1930 int pslot;
1931 int orig_slot = path->slots[level];
1932
1933 if (level == 0)
1934 return 1;
1935
1936 mid = path->nodes[level];
1937 WARN_ON(btrfs_header_generation(mid) != trans->transid);
1938
1939 if (level < BTRFS_MAX_LEVEL - 1) {
1940 parent = path->nodes[level + 1];
1941 pslot = path->slots[level + 1];
1942 }
1943
1944 if (!parent)
1945 return 1;
1946
1947 left = read_node_slot(root, parent, pslot - 1);
1948
1949 /* first, try to make some room in the middle buffer */
1950 if (left) {
1951 u32 left_nr;
1952
1953 btrfs_tree_lock(left);
1954 btrfs_set_lock_blocking(left);
1955
1956 left_nr = btrfs_header_nritems(left);
1957 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1958 wret = 1;
1959 } else {
1960 ret = btrfs_cow_block(trans, root, left, parent,
1961 pslot - 1, &left);
1962 if (ret)
1963 wret = 1;
1964 else {
1965 wret = push_node_left(trans, root,
1966 left, mid, 0);
1967 }
1968 }
1969 if (wret < 0)
1970 ret = wret;
1971 if (wret == 0) {
1972 struct btrfs_disk_key disk_key;
1973 orig_slot += left_nr;
1974 btrfs_node_key(mid, &disk_key, 0);
1975 tree_mod_log_set_node_key(root->fs_info, parent,
1976 pslot, 0);
1977 btrfs_set_node_key(parent, &disk_key, pslot);
1978 btrfs_mark_buffer_dirty(parent);
1979 if (btrfs_header_nritems(left) > orig_slot) {
1980 path->nodes[level] = left;
1981 path->slots[level + 1] -= 1;
1982 path->slots[level] = orig_slot;
1983 btrfs_tree_unlock(mid);
1984 free_extent_buffer(mid);
1985 } else {
1986 orig_slot -=
1987 btrfs_header_nritems(left);
1988 path->slots[level] = orig_slot;
1989 btrfs_tree_unlock(left);
1990 free_extent_buffer(left);
1991 }
1992 return 0;
1993 }
1994 btrfs_tree_unlock(left);
1995 free_extent_buffer(left);
1996 }
1997 right = read_node_slot(root, parent, pslot + 1);
1998
1999 /*
2000 * then try to empty the right most buffer into the middle
2001 */
2002 if (right) {
2003 u32 right_nr;
2004
2005 btrfs_tree_lock(right);
2006 btrfs_set_lock_blocking(right);
2007
2008 right_nr = btrfs_header_nritems(right);
2009 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
2010 wret = 1;
2011 } else {
2012 ret = btrfs_cow_block(trans, root, right,
2013 parent, pslot + 1,
2014 &right);
2015 if (ret)
2016 wret = 1;
2017 else {
2018 wret = balance_node_right(trans, root,
2019 right, mid);
2020 }
2021 }
2022 if (wret < 0)
2023 ret = wret;
2024 if (wret == 0) {
2025 struct btrfs_disk_key disk_key;
2026
2027 btrfs_node_key(right, &disk_key, 0);
2028 tree_mod_log_set_node_key(root->fs_info, parent,
2029 pslot + 1, 0);
2030 btrfs_set_node_key(parent, &disk_key, pslot + 1);
2031 btrfs_mark_buffer_dirty(parent);
2032
2033 if (btrfs_header_nritems(mid) <= orig_slot) {
2034 path->nodes[level] = right;
2035 path->slots[level + 1] += 1;
2036 path->slots[level] = orig_slot -
2037 btrfs_header_nritems(mid);
2038 btrfs_tree_unlock(mid);
2039 free_extent_buffer(mid);
2040 } else {
2041 btrfs_tree_unlock(right);
2042 free_extent_buffer(right);
2043 }
2044 return 0;
2045 }
2046 btrfs_tree_unlock(right);
2047 free_extent_buffer(right);
2048 }
2049 return 1;
2050 }
2051
2052 /*
2053 * readahead one full node of leaves, finding things that are close
2054 * to the block in 'slot', and triggering ra on them.
2055 */
2056 static void reada_for_search(struct btrfs_root *root,
2057 struct btrfs_path *path,
2058 int level, int slot, u64 objectid)
2059 {
2060 struct extent_buffer *node;
2061 struct btrfs_disk_key disk_key;
2062 u32 nritems;
2063 u64 search;
2064 u64 target;
2065 u64 nread = 0;
2066 u64 gen;
2067 int direction = path->reada;
2068 struct extent_buffer *eb;
2069 u32 nr;
2070 u32 blocksize;
2071 u32 nscan = 0;
2072
2073 if (level != 1)
2074 return;
2075
2076 if (!path->nodes[level])
2077 return;
2078
2079 node = path->nodes[level];
2080
2081 search = btrfs_node_blockptr(node, slot);
2082 blocksize = btrfs_level_size(root, level - 1);
2083 eb = btrfs_find_tree_block(root, search, blocksize);
2084 if (eb) {
2085 free_extent_buffer(eb);
2086 return;
2087 }
2088
2089 target = search;
2090
2091 nritems = btrfs_header_nritems(node);
2092 nr = slot;
2093
2094 while (1) {
2095 if (direction < 0) {
2096 if (nr == 0)
2097 break;
2098 nr--;
2099 } else if (direction > 0) {
2100 nr++;
2101 if (nr >= nritems)
2102 break;
2103 }
2104 if (path->reada < 0 && objectid) {
2105 btrfs_node_key(node, &disk_key, nr);
2106 if (btrfs_disk_key_objectid(&disk_key) != objectid)
2107 break;
2108 }
2109 search = btrfs_node_blockptr(node, nr);
2110 if ((search <= target && target - search <= 65536) ||
2111 (search > target && search - target <= 65536)) {
2112 gen = btrfs_node_ptr_generation(node, nr);
2113 readahead_tree_block(root, search, blocksize, gen);
2114 nread += blocksize;
2115 }
2116 nscan++;
2117 if ((nread > 65536 || nscan > 32))
2118 break;
2119 }
2120 }
2121
2122 /*
2123 * returns -EAGAIN if it had to drop the path, or zero if everything was in
2124 * cache
2125 */
2126 static noinline int reada_for_balance(struct btrfs_root *root,
2127 struct btrfs_path *path, int level)
2128 {
2129 int slot;
2130 int nritems;
2131 struct extent_buffer *parent;
2132 struct extent_buffer *eb;
2133 u64 gen;
2134 u64 block1 = 0;
2135 u64 block2 = 0;
2136 int ret = 0;
2137 int blocksize;
2138
2139 parent = path->nodes[level + 1];
2140 if (!parent)
2141 return 0;
2142
2143 nritems = btrfs_header_nritems(parent);
2144 slot = path->slots[level + 1];
2145 blocksize = btrfs_level_size(root, level);
2146
2147 if (slot > 0) {
2148 block1 = btrfs_node_blockptr(parent, slot - 1);
2149 gen = btrfs_node_ptr_generation(parent, slot - 1);
2150 eb = btrfs_find_tree_block(root, block1, blocksize);
2151 /*
2152 * if we get -eagain from btrfs_buffer_uptodate, we
2153 * don't want to return eagain here. That will loop
2154 * forever
2155 */
2156 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2157 block1 = 0;
2158 free_extent_buffer(eb);
2159 }
2160 if (slot + 1 < nritems) {
2161 block2 = btrfs_node_blockptr(parent, slot + 1);
2162 gen = btrfs_node_ptr_generation(parent, slot + 1);
2163 eb = btrfs_find_tree_block(root, block2, blocksize);
2164 if (eb && btrfs_buffer_uptodate(eb, gen, 1) != 0)
2165 block2 = 0;
2166 free_extent_buffer(eb);
2167 }
2168 if (block1 || block2) {
2169 ret = -EAGAIN;
2170
2171 /* release the whole path */
2172 btrfs_release_path(path);
2173
2174 /* read the blocks */
2175 if (block1)
2176 readahead_tree_block(root, block1, blocksize, 0);
2177 if (block2)
2178 readahead_tree_block(root, block2, blocksize, 0);
2179
2180 if (block1) {
2181 eb = read_tree_block(root, block1, blocksize, 0);
2182 free_extent_buffer(eb);
2183 }
2184 if (block2) {
2185 eb = read_tree_block(root, block2, blocksize, 0);
2186 free_extent_buffer(eb);
2187 }
2188 }
2189 return ret;
2190 }
2191
2192
2193 /*
2194 * when we walk down the tree, it is usually safe to unlock the higher layers
2195 * in the tree. The exceptions are when our path goes through slot 0, because
2196 * operations on the tree might require changing key pointers higher up in the
2197 * tree.
2198 *
2199 * callers might also have set path->keep_locks, which tells this code to keep
2200 * the lock if the path points to the last slot in the block. This is part of
2201 * walking through the tree, and selecting the next slot in the higher block.
2202 *
2203 * lowest_unlock sets the lowest level in the tree we're allowed to unlock. so
2204 * if lowest_unlock is 1, level 0 won't be unlocked
2205 */
2206 static noinline void unlock_up(struct btrfs_path *path, int level,
2207 int lowest_unlock, int min_write_lock_level,
2208 int *write_lock_level)
2209 {
2210 int i;
2211 int skip_level = level;
2212 int no_skips = 0;
2213 struct extent_buffer *t;
2214
2215 if (path->really_keep_locks)
2216 return;
2217
2218 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2219 if (!path->nodes[i])
2220 break;
2221 if (!path->locks[i])
2222 break;
2223 if (!no_skips && path->slots[i] == 0) {
2224 skip_level = i + 1;
2225 continue;
2226 }
2227 if (!no_skips && path->keep_locks) {
2228 u32 nritems;
2229 t = path->nodes[i];
2230 nritems = btrfs_header_nritems(t);
2231 if (nritems < 1 || path->slots[i] >= nritems - 1) {
2232 skip_level = i + 1;
2233 continue;
2234 }
2235 }
2236 if (skip_level < i && i >= lowest_unlock)
2237 no_skips = 1;
2238
2239 t = path->nodes[i];
2240 if (i >= lowest_unlock && i > skip_level && path->locks[i]) {
2241 btrfs_tree_unlock_rw(t, path->locks[i]);
2242 path->locks[i] = 0;
2243 if (write_lock_level &&
2244 i > min_write_lock_level &&
2245 i <= *write_lock_level) {
2246 *write_lock_level = i - 1;
2247 }
2248 }
2249 }
2250 }
2251
2252 /*
2253 * This releases any locks held in the path starting at level and
2254 * going all the way up to the root.
2255 *
2256 * btrfs_search_slot will keep the lock held on higher nodes in a few
2257 * corner cases, such as COW of the block at slot zero in the node. This
2258 * ignores those rules, and it should only be called when there are no
2259 * more updates to be done higher up in the tree.
2260 */
2261 noinline void btrfs_unlock_up_safe(struct btrfs_path *path, int level)
2262 {
2263 int i;
2264
2265 if (path->keep_locks || path->really_keep_locks)
2266 return;
2267
2268 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2269 if (!path->nodes[i])
2270 continue;
2271 if (!path->locks[i])
2272 continue;
2273 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
2274 path->locks[i] = 0;
2275 }
2276 }
2277
2278 /*
2279 * helper function for btrfs_search_slot. The goal is to find a block
2280 * in cache without setting the path to blocking. If we find the block
2281 * we return zero and the path is unchanged.
2282 *
2283 * If we can't find the block, we set the path blocking and do some
2284 * reada. -EAGAIN is returned and the search must be repeated.
2285 */
2286 static int
2287 read_block_for_search(struct btrfs_trans_handle *trans,
2288 struct btrfs_root *root, struct btrfs_path *p,
2289 struct extent_buffer **eb_ret, int level, int slot,
2290 struct btrfs_key *key, u64 time_seq)
2291 {
2292 u64 blocknr;
2293 u64 gen;
2294 u32 blocksize;
2295 struct extent_buffer *b = *eb_ret;
2296 struct extent_buffer *tmp;
2297 int ret;
2298
2299 blocknr = btrfs_node_blockptr(b, slot);
2300 gen = btrfs_node_ptr_generation(b, slot);
2301 blocksize = btrfs_level_size(root, level - 1);
2302
2303 tmp = btrfs_find_tree_block(root, blocknr, blocksize);
2304 if (tmp) {
2305 /* first we do an atomic uptodate check */
2306 if (btrfs_buffer_uptodate(tmp, 0, 1) > 0) {
2307 if (btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
2308 /*
2309 * we found an up to date block without
2310 * sleeping, return
2311 * right away
2312 */
2313 *eb_ret = tmp;
2314 return 0;
2315 }
2316 /* the pages were up to date, but we failed
2317 * the generation number check. Do a full
2318 * read for the generation number that is correct.
2319 * We must do this without dropping locks so
2320 * we can trust our generation number
2321 */
2322 free_extent_buffer(tmp);
2323 btrfs_set_path_blocking(p);
2324
2325 /* now we're allowed to do a blocking uptodate check */
2326 tmp = read_tree_block(root, blocknr, blocksize, gen);
2327 if (tmp && btrfs_buffer_uptodate(tmp, gen, 0) > 0) {
2328 *eb_ret = tmp;
2329 return 0;
2330 }
2331 free_extent_buffer(tmp);
2332 btrfs_release_path(p);
2333 return -EIO;
2334 }
2335 }
2336
2337 /*
2338 * reduce lock contention at high levels
2339 * of the btree by dropping locks before
2340 * we read. Don't release the lock on the current
2341 * level because we need to walk this node to figure
2342 * out which blocks to read.
2343 */
2344 btrfs_unlock_up_safe(p, level + 1);
2345 btrfs_set_path_blocking(p);
2346
2347 free_extent_buffer(tmp);
2348 if (p->reada)
2349 reada_for_search(root, p, level, slot, key->objectid);
2350
2351 btrfs_release_path(p);
2352
2353 ret = -EAGAIN;
2354 tmp = read_tree_block(root, blocknr, blocksize, 0);
2355 if (tmp) {
2356 /*
2357 * If the read above didn't mark this buffer up to date,
2358 * it will never end up being up to date. Set ret to EIO now
2359 * and give up so that our caller doesn't loop forever
2360 * on our EAGAINs.
2361 */
2362 if (!btrfs_buffer_uptodate(tmp, 0, 0))
2363 ret = -EIO;
2364 free_extent_buffer(tmp);
2365 }
2366 return ret;
2367 }
2368
2369 /*
2370 * helper function for btrfs_search_slot. This does all of the checks
2371 * for node-level blocks and does any balancing required based on
2372 * the ins_len.
2373 *
2374 * If no extra work was required, zero is returned. If we had to
2375 * drop the path, -EAGAIN is returned and btrfs_search_slot must
2376 * start over
2377 */
2378 static int
2379 setup_nodes_for_search(struct btrfs_trans_handle *trans,
2380 struct btrfs_root *root, struct btrfs_path *p,
2381 struct extent_buffer *b, int level, int ins_len,
2382 int *write_lock_level)
2383 {
2384 int ret;
2385 if ((p->search_for_split || ins_len > 0) && btrfs_header_nritems(b) >=
2386 BTRFS_NODEPTRS_PER_BLOCK(root) - 3) {
2387 int sret;
2388
2389 if (*write_lock_level < level + 1) {
2390 *write_lock_level = level + 1;
2391 btrfs_release_path(p);
2392 goto again;
2393 }
2394
2395 sret = reada_for_balance(root, p, level);
2396 if (sret)
2397 goto again;
2398
2399 btrfs_set_path_blocking(p);
2400 sret = split_node(trans, root, p, level);
2401 btrfs_clear_path_blocking(p, NULL, 0);
2402
2403 BUG_ON(sret > 0);
2404 if (sret) {
2405 ret = sret;
2406 goto done;
2407 }
2408 b = p->nodes[level];
2409 } else if (ins_len < 0 && btrfs_header_nritems(b) <
2410 BTRFS_NODEPTRS_PER_BLOCK(root) / 2) {
2411 int sret;
2412
2413 if (*write_lock_level < level + 1) {
2414 *write_lock_level = level + 1;
2415 btrfs_release_path(p);
2416 goto again;
2417 }
2418
2419 sret = reada_for_balance(root, p, level);
2420 if (sret)
2421 goto again;
2422
2423 btrfs_set_path_blocking(p);
2424 sret = balance_level(trans, root, p, level);
2425 btrfs_clear_path_blocking(p, NULL, 0);
2426
2427 if (sret) {
2428 ret = sret;
2429 goto done;
2430 }
2431 b = p->nodes[level];
2432 if (!b) {
2433 btrfs_release_path(p);
2434 goto again;
2435 }
2436 BUG_ON(btrfs_header_nritems(b) == 1);
2437 }
2438 return 0;
2439
2440 again:
2441 ret = -EAGAIN;
2442 done:
2443 return ret;
2444 }
2445
2446 /*
2447 * look for key in the tree. path is filled in with nodes along the way
2448 * if key is found, we return zero and you can find the item in the leaf
2449 * level of the path (level 0)
2450 *
2451 * If the key isn't found, the path points to the slot where it should
2452 * be inserted, and 1 is returned. If there are other errors during the
2453 * search a negative error number is returned.
2454 *
2455 * if ins_len > 0, nodes and leaves will be split as we walk down the
2456 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
2457 * possible)
2458 */
2459 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
2460 *root, struct btrfs_key *key, struct btrfs_path *p, int
2461 ins_len, int cow)
2462 {
2463 struct extent_buffer *b;
2464 int slot;
2465 int ret;
2466 int err;
2467 int level;
2468 int lowest_unlock = 1;
2469 int root_lock;
2470 /* everything at write_lock_level or lower must be write locked */
2471 int write_lock_level = 0;
2472 u8 lowest_level = 0;
2473 int min_write_lock_level;
2474
2475 lowest_level = p->lowest_level;
2476 WARN_ON(lowest_level && ins_len > 0);
2477 WARN_ON(p->nodes[0] != NULL);
2478
2479 if (ins_len < 0) {
2480 lowest_unlock = 2;
2481
2482 /* when we are removing items, we might have to go up to level
2483 * two as we update tree pointers Make sure we keep write
2484 * for those levels as well
2485 */
2486 write_lock_level = 2;
2487 } else if (ins_len > 0) {
2488 /*
2489 * for inserting items, make sure we have a write lock on
2490 * level 1 so we can update keys
2491 */
2492 write_lock_level = 1;
2493 }
2494
2495 if (!cow)
2496 write_lock_level = -1;
2497
2498 if (cow && (p->really_keep_locks || p->keep_locks || p->lowest_level))
2499 write_lock_level = BTRFS_MAX_LEVEL;
2500
2501 min_write_lock_level = write_lock_level;
2502
2503 again:
2504 /*
2505 * we try very hard to do read locks on the root
2506 */
2507 root_lock = BTRFS_READ_LOCK;
2508 level = 0;
2509 if (p->search_commit_root) {
2510 /*
2511 * the commit roots are read only
2512 * so we always do read locks
2513 */
2514 b = root->commit_root;
2515 extent_buffer_get(b);
2516 level = btrfs_header_level(b);
2517 if (!p->skip_locking)
2518 btrfs_tree_read_lock(b);
2519 } else {
2520 if (p->skip_locking) {
2521 b = btrfs_root_node(root);
2522 level = btrfs_header_level(b);
2523 } else {
2524 /* we don't know the level of the root node
2525 * until we actually have it read locked
2526 */
2527 b = btrfs_read_lock_root_node(root);
2528 level = btrfs_header_level(b);
2529 if (level <= write_lock_level) {
2530 /* whoops, must trade for write lock */
2531 btrfs_tree_read_unlock(b);
2532 free_extent_buffer(b);
2533 b = btrfs_lock_root_node(root);
2534 root_lock = BTRFS_WRITE_LOCK;
2535
2536 /* the level might have changed, check again */
2537 level = btrfs_header_level(b);
2538 }
2539 }
2540 }
2541 p->nodes[level] = b;
2542 if (!p->skip_locking)
2543 p->locks[level] = root_lock;
2544
2545 while (b) {
2546 level = btrfs_header_level(b);
2547
2548 /*
2549 * setup the path here so we can release it under lock
2550 * contention with the cow code
2551 */
2552 if (cow) {
2553 /*
2554 * if we don't really need to cow this block
2555 * then we don't want to set the path blocking,
2556 * so we test it here
2557 */
2558 if (!should_cow_block(trans, root, b))
2559 goto cow_done;
2560
2561 btrfs_set_path_blocking(p);
2562
2563 /*
2564 * must have write locks on this node and the
2565 * parent
2566 */
2567 if (level > write_lock_level ||
2568 (level + 1 > write_lock_level &&
2569 level + 1 < BTRFS_MAX_LEVEL &&
2570 p->nodes[level + 1])) {
2571 write_lock_level = level + 1;
2572 btrfs_release_path(p);
2573 goto again;
2574 }
2575
2576 err = btrfs_cow_block(trans, root, b,
2577 p->nodes[level + 1],
2578 p->slots[level + 1], &b);
2579 if (err) {
2580 ret = err;
2581 goto done;
2582 }
2583 }
2584 cow_done:
2585 BUG_ON(!cow && ins_len);
2586
2587 p->nodes[level] = b;
2588 btrfs_clear_path_blocking(p, NULL, 0);
2589
2590 /*
2591 * we have a lock on b and as long as we aren't changing
2592 * the tree, there is no way to for the items in b to change.
2593 * It is safe to drop the lock on our parent before we
2594 * go through the expensive btree search on b.
2595 *
2596 * If cow is true, then we might be changing slot zero,
2597 * which may require changing the parent. So, we can't
2598 * drop the lock until after we know which slot we're
2599 * operating on.
2600 */
2601 if (!cow)
2602 btrfs_unlock_up_safe(p, level + 1);
2603
2604 ret = bin_search(b, key, level, &slot);
2605
2606 if (level != 0) {
2607 int dec = 0;
2608 if (ret && slot > 0) {
2609 dec = 1;
2610 slot -= 1;
2611 }
2612 p->slots[level] = slot;
2613 err = setup_nodes_for_search(trans, root, p, b, level,
2614 ins_len, &write_lock_level);
2615 if (err == -EAGAIN)
2616 goto again;
2617 if (err) {
2618 ret = err;
2619 goto done;
2620 }
2621 b = p->nodes[level];
2622 slot = p->slots[level];
2623
2624 /*
2625 * slot 0 is special, if we change the key
2626 * we have to update the parent pointer
2627 * which means we must have a write lock
2628 * on the parent
2629 */
2630 if (slot == 0 && cow &&
2631 write_lock_level < level + 1) {
2632 write_lock_level = level + 1;
2633 btrfs_release_path(p);
2634 goto again;
2635 }
2636
2637 unlock_up(p, level, lowest_unlock,
2638 min_write_lock_level, &write_lock_level);
2639
2640 if (level == lowest_level) {
2641 if (dec)
2642 p->slots[level]++;
2643 goto done;
2644 }
2645
2646 err = read_block_for_search(trans, root, p,
2647 &b, level, slot, key, 0);
2648 if (err == -EAGAIN)
2649 goto again;
2650 if (err) {
2651 ret = err;
2652 goto done;
2653 }
2654
2655 if (!p->skip_locking) {
2656 level = btrfs_header_level(b);
2657 if (level <= write_lock_level) {
2658 err = btrfs_try_tree_write_lock(b);
2659 if (!err) {
2660 btrfs_set_path_blocking(p);
2661 btrfs_tree_lock(b);
2662 btrfs_clear_path_blocking(p, b,
2663 BTRFS_WRITE_LOCK);
2664 }
2665 p->locks[level] = BTRFS_WRITE_LOCK;
2666 } else {
2667 err = btrfs_try_tree_read_lock(b);
2668 if (!err) {
2669 btrfs_set_path_blocking(p);
2670 btrfs_tree_read_lock(b);
2671 btrfs_clear_path_blocking(p, b,
2672 BTRFS_READ_LOCK);
2673 }
2674 p->locks[level] = BTRFS_READ_LOCK;
2675 }
2676 p->nodes[level] = b;
2677 }
2678 } else {
2679 p->slots[level] = slot;
2680 if (ins_len > 0 &&
2681 btrfs_leaf_free_space(root, b) < ins_len) {
2682 if (write_lock_level < 1) {
2683 write_lock_level = 1;
2684 btrfs_release_path(p);
2685 goto again;
2686 }
2687
2688 btrfs_set_path_blocking(p);
2689 err = split_leaf(trans, root, key,
2690 p, ins_len, ret == 0);
2691 btrfs_clear_path_blocking(p, NULL, 0);
2692
2693 BUG_ON(err > 0);
2694 if (err) {
2695 ret = err;
2696 goto done;
2697 }
2698 }
2699 if (!p->search_for_split)
2700 unlock_up(p, level, lowest_unlock,
2701 min_write_lock_level, &write_lock_level);
2702 goto done;
2703 }
2704 }
2705 ret = 1;
2706 done:
2707 /*
2708 * we don't really know what they plan on doing with the path
2709 * from here on, so for now just mark it as blocking
2710 */
2711 if (!p->leave_spinning)
2712 btrfs_set_path_blocking(p);
2713 if (ret < 0)
2714 btrfs_release_path(p);
2715 return ret;
2716 }
2717
2718 /*
2719 * Like btrfs_search_slot, this looks for a key in the given tree. It uses the
2720 * current state of the tree together with the operations recorded in the tree
2721 * modification log to search for the key in a previous version of this tree, as
2722 * denoted by the time_seq parameter.
2723 *
2724 * Naturally, there is no support for insert, delete or cow operations.
2725 *
2726 * The resulting path and return value will be set up as if we called
2727 * btrfs_search_slot at that point in time with ins_len and cow both set to 0.
2728 */
2729 int btrfs_search_old_slot(struct btrfs_root *root, struct btrfs_key *key,
2730 struct btrfs_path *p, u64 time_seq)
2731 {
2732 struct extent_buffer *b;
2733 int slot;
2734 int ret;
2735 int err;
2736 int level;
2737 int lowest_unlock = 1;
2738 u8 lowest_level = 0;
2739
2740 lowest_level = p->lowest_level;
2741 WARN_ON(p->nodes[0] != NULL);
2742
2743 if (p->search_commit_root) {
2744 BUG_ON(time_seq);
2745 return btrfs_search_slot(NULL, root, key, p, 0, 0);
2746 }
2747
2748 again:
2749 b = get_old_root(root, time_seq);
2750 level = btrfs_header_level(b);
2751 p->locks[level] = BTRFS_READ_LOCK;
2752
2753 while (b) {
2754 level = btrfs_header_level(b);
2755 p->nodes[level] = b;
2756 btrfs_clear_path_blocking(p, NULL, 0);
2757
2758 /*
2759 * we have a lock on b and as long as we aren't changing
2760 * the tree, there is no way to for the items in b to change.
2761 * It is safe to drop the lock on our parent before we
2762 * go through the expensive btree search on b.
2763 */
2764 btrfs_unlock_up_safe(p, level + 1);
2765
2766 ret = bin_search(b, key, level, &slot);
2767
2768 if (level != 0) {
2769 int dec = 0;
2770 if (ret && slot > 0) {
2771 dec = 1;
2772 slot -= 1;
2773 }
2774 p->slots[level] = slot;
2775 unlock_up(p, level, lowest_unlock, 0, NULL);
2776
2777 if (level == lowest_level) {
2778 if (dec)
2779 p->slots[level]++;
2780 goto done;
2781 }
2782
2783 err = read_block_for_search(NULL, root, p, &b, level,
2784 slot, key, time_seq);
2785 if (err == -EAGAIN)
2786 goto again;
2787 if (err) {
2788 ret = err;
2789 goto done;
2790 }
2791
2792 level = btrfs_header_level(b);
2793 err = btrfs_try_tree_read_lock(b);
2794 if (!err) {
2795 btrfs_set_path_blocking(p);
2796 btrfs_tree_read_lock(b);
2797 btrfs_clear_path_blocking(p, b,
2798 BTRFS_READ_LOCK);
2799 }
2800 p->locks[level] = BTRFS_READ_LOCK;
2801 p->nodes[level] = b;
2802 b = tree_mod_log_rewind(root->fs_info, b, time_seq);
2803 if (b != p->nodes[level]) {
2804 btrfs_tree_unlock_rw(p->nodes[level],
2805 p->locks[level]);
2806 p->locks[level] = 0;
2807 p->nodes[level] = b;
2808 }
2809 } else {
2810 p->slots[level] = slot;
2811 unlock_up(p, level, lowest_unlock, 0, NULL);
2812 goto done;
2813 }
2814 }
2815 ret = 1;
2816 done:
2817 if (!p->leave_spinning)
2818 btrfs_set_path_blocking(p);
2819 if (ret < 0)
2820 btrfs_release_path(p);
2821
2822 return ret;
2823 }
2824
2825 /*
2826 * helper to use instead of search slot if no exact match is needed but
2827 * instead the next or previous item should be returned.
2828 * When find_higher is true, the next higher item is returned, the next lower
2829 * otherwise.
2830 * When return_any and find_higher are both true, and no higher item is found,
2831 * return the next lower instead.
2832 * When return_any is true and find_higher is false, and no lower item is found,
2833 * return the next higher instead.
2834 * It returns 0 if any item is found, 1 if none is found (tree empty), and
2835 * < 0 on error
2836 */
2837 int btrfs_search_slot_for_read(struct btrfs_root *root,
2838 struct btrfs_key *key, struct btrfs_path *p,
2839 int find_higher, int return_any)
2840 {
2841 int ret;
2842 struct extent_buffer *leaf;
2843
2844 again:
2845 ret = btrfs_search_slot(NULL, root, key, p, 0, 0);
2846 if (ret <= 0)
2847 return ret;
2848 /*
2849 * a return value of 1 means the path is at the position where the
2850 * item should be inserted. Normally this is the next bigger item,
2851 * but in case the previous item is the last in a leaf, path points
2852 * to the first free slot in the previous leaf, i.e. at an invalid
2853 * item.
2854 */
2855 leaf = p->nodes[0];
2856
2857 if (find_higher) {
2858 if (p->slots[0] >= btrfs_header_nritems(leaf)) {
2859 ret = btrfs_next_leaf(root, p);
2860 if (ret <= 0)
2861 return ret;
2862 if (!return_any)
2863 return 1;
2864 /*
2865 * no higher item found, return the next
2866 * lower instead
2867 */
2868 return_any = 0;
2869 find_higher = 0;
2870 btrfs_release_path(p);
2871 goto again;
2872 }
2873 } else {
2874 if (p->slots[0] == 0) {
2875 ret = btrfs_prev_leaf(root, p);
2876 if (ret < 0)
2877 return ret;
2878 if (!ret) {
2879 p->slots[0] = btrfs_header_nritems(leaf) - 1;
2880 return 0;
2881 }
2882 if (!return_any)
2883 return 1;
2884 /*
2885 * no lower item found, return the next
2886 * higher instead
2887 */
2888 return_any = 0;
2889 find_higher = 1;
2890 btrfs_release_path(p);
2891 goto again;
2892 } else {
2893 --p->slots[0];
2894 }
2895 }
2896 return 0;
2897 }
2898
2899 /*
2900 * adjust the pointers going up the tree, starting at level
2901 * making sure the right key of each node is points to 'key'.
2902 * This is used after shifting pointers to the left, so it stops
2903 * fixing up pointers when a given leaf/node is not in slot 0 of the
2904 * higher levels
2905 *
2906 */
2907 static void fixup_low_keys(struct btrfs_trans_handle *trans,
2908 struct btrfs_root *root, struct btrfs_path *path,
2909 struct btrfs_disk_key *key, int level)
2910 {
2911 int i;
2912 struct extent_buffer *t;
2913
2914 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
2915 int tslot = path->slots[i];
2916 if (!path->nodes[i])
2917 break;
2918 t = path->nodes[i];
2919 tree_mod_log_set_node_key(root->fs_info, t, tslot, 1);
2920 btrfs_set_node_key(t, key, tslot);
2921 btrfs_mark_buffer_dirty(path->nodes[i]);
2922 if (tslot != 0)
2923 break;
2924 }
2925 }
2926
2927 /*
2928 * update item key.
2929 *
2930 * This function isn't completely safe. It's the caller's responsibility
2931 * that the new key won't break the order
2932 */
2933 void btrfs_set_item_key_safe(struct btrfs_trans_handle *trans,
2934 struct btrfs_root *root, struct btrfs_path *path,
2935 struct btrfs_key *new_key)
2936 {
2937 struct btrfs_disk_key disk_key;
2938 struct extent_buffer *eb;
2939 int slot;
2940
2941 eb = path->nodes[0];
2942 slot = path->slots[0];
2943 if (slot > 0) {
2944 btrfs_item_key(eb, &disk_key, slot - 1);
2945 BUG_ON(comp_keys(&disk_key, new_key) >= 0);
2946 }
2947 if (slot < btrfs_header_nritems(eb) - 1) {
2948 btrfs_item_key(eb, &disk_key, slot + 1);
2949 BUG_ON(comp_keys(&disk_key, new_key) <= 0);
2950 }
2951
2952 btrfs_cpu_key_to_disk(&disk_key, new_key);
2953 btrfs_set_item_key(eb, &disk_key, slot);
2954 btrfs_mark_buffer_dirty(eb);
2955 if (slot == 0)
2956 fixup_low_keys(trans, root, path, &disk_key, 1);
2957 }
2958
2959 /*
2960 * try to push data from one node into the next node left in the
2961 * tree.
2962 *
2963 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
2964 * error, and > 0 if there was no room in the left hand block.
2965 */
2966 static int push_node_left(struct btrfs_trans_handle *trans,
2967 struct btrfs_root *root, struct extent_buffer *dst,
2968 struct extent_buffer *src, int empty)
2969 {
2970 int push_items = 0;
2971 int src_nritems;
2972 int dst_nritems;
2973 int ret = 0;
2974
2975 src_nritems = btrfs_header_nritems(src);
2976 dst_nritems = btrfs_header_nritems(dst);
2977 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
2978 WARN_ON(btrfs_header_generation(src) != trans->transid);
2979 WARN_ON(btrfs_header_generation(dst) != trans->transid);
2980
2981 if (!empty && src_nritems <= 8)
2982 return 1;
2983
2984 if (push_items <= 0)
2985 return 1;
2986
2987 if (empty) {
2988 push_items = min(src_nritems, push_items);
2989 if (push_items < src_nritems) {
2990 /* leave at least 8 pointers in the node if
2991 * we aren't going to empty it
2992 */
2993 if (src_nritems - push_items < 8) {
2994 if (push_items <= 8)
2995 return 1;
2996 push_items -= 8;
2997 }
2998 }
2999 } else
3000 push_items = min(src_nritems - 8, push_items);
3001
3002 tree_mod_log_eb_copy(root->fs_info, dst, src, dst_nritems, 0,
3003 push_items);
3004 copy_extent_buffer(dst, src,
3005 btrfs_node_key_ptr_offset(dst_nritems),
3006 btrfs_node_key_ptr_offset(0),
3007 push_items * sizeof(struct btrfs_key_ptr));
3008
3009 if (push_items < src_nritems) {
3010 /*
3011 * don't call tree_mod_log_eb_move here, key removal was already
3012 * fully logged by tree_mod_log_eb_copy above.
3013 */
3014 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
3015 btrfs_node_key_ptr_offset(push_items),
3016 (src_nritems - push_items) *
3017 sizeof(struct btrfs_key_ptr));
3018 }
3019 btrfs_set_header_nritems(src, src_nritems - push_items);
3020 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3021 btrfs_mark_buffer_dirty(src);
3022 btrfs_mark_buffer_dirty(dst);
3023
3024 return ret;
3025 }
3026
3027 /*
3028 * try to push data from one node into the next node right in the
3029 * tree.
3030 *
3031 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
3032 * error, and > 0 if there was no room in the right hand block.
3033 *
3034 * this will only push up to 1/2 the contents of the left node over
3035 */
3036 static int balance_node_right(struct btrfs_trans_handle *trans,
3037 struct btrfs_root *root,
3038 struct extent_buffer *dst,
3039 struct extent_buffer *src)
3040 {
3041 int push_items = 0;
3042 int max_push;
3043 int src_nritems;
3044 int dst_nritems;
3045 int ret = 0;
3046
3047 WARN_ON(btrfs_header_generation(src) != trans->transid);
3048 WARN_ON(btrfs_header_generation(dst) != trans->transid);
3049
3050 src_nritems = btrfs_header_nritems(src);
3051 dst_nritems = btrfs_header_nritems(dst);
3052 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
3053 if (push_items <= 0)
3054 return 1;
3055
3056 if (src_nritems < 4)
3057 return 1;
3058
3059 max_push = src_nritems / 2 + 1;
3060 /* don't try to empty the node */
3061 if (max_push >= src_nritems)
3062 return 1;
3063
3064 if (max_push < push_items)
3065 push_items = max_push;
3066
3067 tree_mod_log_eb_move(root->fs_info, dst, push_items, 0, dst_nritems);
3068 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
3069 btrfs_node_key_ptr_offset(0),
3070 (dst_nritems) *
3071 sizeof(struct btrfs_key_ptr));
3072
3073 tree_mod_log_eb_copy(root->fs_info, dst, src, 0,
3074 src_nritems - push_items, push_items);
3075 copy_extent_buffer(dst, src,
3076 btrfs_node_key_ptr_offset(0),
3077 btrfs_node_key_ptr_offset(src_nritems - push_items),
3078 push_items * sizeof(struct btrfs_key_ptr));
3079
3080 btrfs_set_header_nritems(src, src_nritems - push_items);
3081 btrfs_set_header_nritems(dst, dst_nritems + push_items);
3082
3083 btrfs_mark_buffer_dirty(src);
3084 btrfs_mark_buffer_dirty(dst);
3085
3086 return ret;
3087 }
3088
3089 /*
3090 * helper function to insert a new root level in the tree.
3091 * A new node is allocated, and a single item is inserted to
3092 * point to the existing root
3093 *
3094 * returns zero on success or < 0 on failure.
3095 */
3096 static noinline int insert_new_root(struct btrfs_trans_handle *trans,
3097 struct btrfs_root *root,
3098 struct btrfs_path *path, int level)
3099 {
3100 u64 lower_gen;
3101 struct extent_buffer *lower;
3102 struct extent_buffer *c;
3103 struct extent_buffer *old;
3104 struct btrfs_disk_key lower_key;
3105
3106 BUG_ON(path->nodes[level]);
3107 BUG_ON(path->nodes[level-1] != root->node);
3108
3109 lower = path->nodes[level-1];
3110 if (level == 1)
3111 btrfs_item_key(lower, &lower_key, 0);
3112 else
3113 btrfs_node_key(lower, &lower_key, 0);
3114
3115 c = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3116 root->root_key.objectid, &lower_key,
3117 level, root->node->start, 0);
3118 if (IS_ERR(c))
3119 return PTR_ERR(c);
3120
3121 root_add_used(root, root->nodesize);
3122
3123 memset_extent_buffer(c, 0, 0, sizeof(struct btrfs_header));
3124 btrfs_set_header_nritems(c, 1);
3125 btrfs_set_header_level(c, level);
3126 btrfs_set_header_bytenr(c, c->start);
3127 btrfs_set_header_generation(c, trans->transid);
3128 btrfs_set_header_backref_rev(c, BTRFS_MIXED_BACKREF_REV);
3129 btrfs_set_header_owner(c, root->root_key.objectid);
3130
3131 write_extent_buffer(c, root->fs_info->fsid,
3132 (unsigned long)btrfs_header_fsid(c),
3133 BTRFS_FSID_SIZE);
3134
3135 write_extent_buffer(c, root->fs_info->chunk_tree_uuid,
3136 (unsigned long)btrfs_header_chunk_tree_uuid(c),
3137 BTRFS_UUID_SIZE);
3138
3139 btrfs_set_node_key(c, &lower_key, 0);
3140 btrfs_set_node_blockptr(c, 0, lower->start);
3141 lower_gen = btrfs_header_generation(lower);
3142 WARN_ON(lower_gen != trans->transid);
3143
3144 btrfs_set_node_ptr_generation(c, 0, lower_gen);
3145
3146 btrfs_mark_buffer_dirty(c);
3147
3148 old = root->node;
3149 tree_mod_log_set_root_pointer(root, c);
3150 rcu_assign_pointer(root->node, c);
3151
3152 /* the super has an extra ref to root->node */
3153 free_extent_buffer(old);
3154
3155 add_root_to_dirty_list(root);
3156 extent_buffer_get(c);
3157 path->nodes[level] = c;
3158 path->locks[level] = BTRFS_WRITE_LOCK;
3159 path->slots[level] = 0;
3160 return 0;
3161 }
3162
3163 /*
3164 * worker function to insert a single pointer in a node.
3165 * the node should have enough room for the pointer already
3166 *
3167 * slot and level indicate where you want the key to go, and
3168 * blocknr is the block the key points to.
3169 */
3170 static void insert_ptr(struct btrfs_trans_handle *trans,
3171 struct btrfs_root *root, struct btrfs_path *path,
3172 struct btrfs_disk_key *key, u64 bytenr,
3173 int slot, int level)
3174 {
3175 struct extent_buffer *lower;
3176 int nritems;
3177 int ret;
3178
3179 BUG_ON(!path->nodes[level]);
3180 btrfs_assert_tree_locked(path->nodes[level]);
3181 lower = path->nodes[level];
3182 nritems = btrfs_header_nritems(lower);
3183 BUG_ON(slot > nritems);
3184 BUG_ON(nritems == BTRFS_NODEPTRS_PER_BLOCK(root));
3185 if (slot != nritems) {
3186 if (level)
3187 tree_mod_log_eb_move(root->fs_info, lower, slot + 1,
3188 slot, nritems - slot);
3189 memmove_extent_buffer(lower,
3190 btrfs_node_key_ptr_offset(slot + 1),
3191 btrfs_node_key_ptr_offset(slot),
3192 (nritems - slot) * sizeof(struct btrfs_key_ptr));
3193 }
3194 if (level) {
3195 ret = tree_mod_log_insert_key(root->fs_info, lower, slot,
3196 MOD_LOG_KEY_ADD);
3197 BUG_ON(ret < 0);
3198 }
3199 btrfs_set_node_key(lower, key, slot);
3200 btrfs_set_node_blockptr(lower, slot, bytenr);
3201 WARN_ON(trans->transid == 0);
3202 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
3203 btrfs_set_header_nritems(lower, nritems + 1);
3204 btrfs_mark_buffer_dirty(lower);
3205 }
3206
3207 /*
3208 * split the node at the specified level in path in two.
3209 * The path is corrected to point to the appropriate node after the split
3210 *
3211 * Before splitting this tries to make some room in the node by pushing
3212 * left and right, if either one works, it returns right away.
3213 *
3214 * returns 0 on success and < 0 on failure
3215 */
3216 static noinline int split_node(struct btrfs_trans_handle *trans,
3217 struct btrfs_root *root,
3218 struct btrfs_path *path, int level)
3219 {
3220 struct extent_buffer *c;
3221 struct extent_buffer *split;
3222 struct btrfs_disk_key disk_key;
3223 int mid;
3224 int ret;
3225 u32 c_nritems;
3226
3227 c = path->nodes[level];
3228 WARN_ON(btrfs_header_generation(c) != trans->transid);
3229 if (c == root->node) {
3230 /* trying to split the root, lets make a new one */
3231 ret = insert_new_root(trans, root, path, level + 1);
3232 if (ret)
3233 return ret;
3234 } else {
3235 ret = push_nodes_for_insert(trans, root, path, level);
3236 c = path->nodes[level];
3237 if (!ret && btrfs_header_nritems(c) <
3238 BTRFS_NODEPTRS_PER_BLOCK(root) - 3)
3239 return 0;
3240 if (ret < 0)
3241 return ret;
3242 }
3243
3244 c_nritems = btrfs_header_nritems(c);
3245 mid = (c_nritems + 1) / 2;
3246 btrfs_node_key(c, &disk_key, mid);
3247
3248 split = btrfs_alloc_free_block(trans, root, root->nodesize, 0,
3249 root->root_key.objectid,
3250 &disk_key, level, c->start, 0);
3251 if (IS_ERR(split))
3252 return PTR_ERR(split);
3253
3254 root_add_used(root, root->nodesize);
3255
3256 memset_extent_buffer(split, 0, 0, sizeof(struct btrfs_header));
3257 btrfs_set_header_level(split, btrfs_header_level(c));
3258 btrfs_set_header_bytenr(split, split->start);
3259 btrfs_set_header_generation(split, trans->transid);
3260 btrfs_set_header_backref_rev(split, BTRFS_MIXED_BACKREF_REV);
3261 btrfs_set_header_owner(split, root->root_key.objectid);
3262 write_extent_buffer(split, root->fs_info->fsid,
3263 (unsigned long)btrfs_header_fsid(split),
3264 BTRFS_FSID_SIZE);
3265 write_extent_buffer(split, root->fs_info->chunk_tree_uuid,
3266 (unsigned long)btrfs_header_chunk_tree_uuid(split),
3267 BTRFS_UUID_SIZE);
3268
3269 tree_mod_log_eb_copy(root->fs_info, split, c, 0, mid, c_nritems - mid);
3270 copy_extent_buffer(split, c,
3271 btrfs_node_key_ptr_offset(0),
3272 btrfs_node_key_ptr_offset(mid),
3273 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
3274 btrfs_set_header_nritems(split, c_nritems - mid);
3275 btrfs_set_header_nritems(c, mid);
3276 ret = 0;
3277
3278 btrfs_mark_buffer_dirty(c);
3279 btrfs_mark_buffer_dirty(split);
3280
3281 insert_ptr(trans, root, path, &disk_key, split->start,
3282 path->slots[level + 1] + 1, level + 1);
3283
3284 if (path->slots[level] >= mid) {
3285 path->slots[level] -= mid;
3286 btrfs_tree_unlock(c);
3287 free_extent_buffer(c);
3288 path->nodes[level] = split;
3289 path->slots[level + 1] += 1;
3290 } else {
3291 btrfs_tree_unlock(split);
3292 free_extent_buffer(split);
3293 }
3294 return ret;
3295 }
3296
3297 /*
3298 * how many bytes are required to store the items in a leaf. start
3299 * and nr indicate which items in the leaf to check. This totals up the
3300 * space used both by the item structs and the item data
3301 */
3302 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
3303 {
3304 struct btrfs_item *start_item;
3305 struct btrfs_item *end_item;
3306 struct btrfs_map_token token;
3307 int data_len;
3308 int nritems = btrfs_header_nritems(l);
3309 int end = min(nritems, start + nr) - 1;
3310
3311 if (!nr)
3312 return 0;
3313 btrfs_init_map_token(&token);
3314 start_item = btrfs_item_nr(l, start);
3315 end_item = btrfs_item_nr(l, end);
3316 data_len = btrfs_token_item_offset(l, start_item, &token) +
3317 btrfs_token_item_size(l, start_item, &token);
3318 data_len = data_len - btrfs_token_item_offset(l, end_item, &token);
3319 data_len += sizeof(struct btrfs_item) * nr;
3320 WARN_ON(data_len < 0);
3321 return data_len;
3322 }
3323
3324 /*
3325 * The space between the end of the leaf items and
3326 * the start of the leaf data. IOW, how much room
3327 * the leaf has left for both items and data
3328 */
3329 noinline int btrfs_leaf_free_space(struct btrfs_root *root,
3330 struct extent_buffer *leaf)
3331 {
3332 int nritems = btrfs_header_nritems(leaf);
3333 int ret;
3334 ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
3335 if (ret < 0) {
3336 printk(KERN_CRIT "leaf free space ret %d, leaf data size %lu, "
3337 "used %d nritems %d\n",
3338 ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
3339 leaf_space_used(leaf, 0, nritems), nritems);
3340 }
3341 return ret;
3342 }
3343
3344 /*
3345 * min slot controls the lowest index we're willing to push to the
3346 * right. We'll push up to and including min_slot, but no lower
3347 */
3348 static noinline int __push_leaf_right(struct btrfs_trans_handle *trans,
3349 struct btrfs_root *root,
3350 struct btrfs_path *path,
3351 int data_size, int empty,
3352 struct extent_buffer *right,
3353 int free_space, u32 left_nritems,
3354 u32 min_slot)
3355 {
3356 struct extent_buffer *left = path->nodes[0];
3357 struct extent_buffer *upper = path->nodes[1];
3358 struct btrfs_map_token token;
3359 struct btrfs_disk_key disk_key;
3360 int slot;
3361 u32 i;
3362 int push_space = 0;
3363 int push_items = 0;
3364 struct btrfs_item *item;
3365 u32 nr;
3366 u32 right_nritems;
3367 u32 data_end;
3368 u32 this_item_size;
3369
3370 btrfs_init_map_token(&token);
3371
3372 if (empty)
3373 nr = 0;
3374 else
3375 nr = max_t(u32, 1, min_slot);
3376
3377 if (path->slots[0] >= left_nritems)
3378 push_space += data_size;
3379
3380 slot = path->slots[1];
3381 i = left_nritems - 1;
3382 while (i >= nr) {
3383 item = btrfs_item_nr(left, i);
3384
3385 if (!empty && push_items > 0) {
3386 if (path->slots[0] > i)
3387 break;
3388 if (path->slots[0] == i) {
3389 int space = btrfs_leaf_free_space(root, left);
3390 if (space + push_space * 2 > free_space)
3391 break;
3392 }
3393 }
3394
3395 if (path->slots[0] == i)
3396 push_space += data_size;
3397
3398 this_item_size = btrfs_item_size(left, item);
3399 if (this_item_size + sizeof(*item) + push_space > free_space)
3400 break;
3401
3402 push_items++;
3403 push_space += this_item_size + sizeof(*item);
3404 if (i == 0)
3405 break;
3406 i--;
3407 }
3408
3409 if (push_items == 0)
3410 goto out_unlock;
3411
3412 WARN_ON(!empty && push_items == left_nritems);
3413
3414 /* push left to right */
3415 right_nritems = btrfs_header_nritems(right);
3416
3417 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
3418 push_space -= leaf_data_end(root, left);
3419
3420 /* make room in the right data area */
3421 data_end = leaf_data_end(root, right);
3422 memmove_extent_buffer(right,
3423 btrfs_leaf_data(right) + data_end - push_space,
3424 btrfs_leaf_data(right) + data_end,
3425 BTRFS_LEAF_DATA_SIZE(root) - data_end);
3426
3427 /* copy from the left data area */
3428 copy_extent_buffer(right, left, btrfs_leaf_data(right) +
3429 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3430 btrfs_leaf_data(left) + leaf_data_end(root, left),
3431 push_space);
3432
3433 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
3434 btrfs_item_nr_offset(0),
3435 right_nritems * sizeof(struct btrfs_item));
3436
3437 /* copy the items from left to right */
3438 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
3439 btrfs_item_nr_offset(left_nritems - push_items),
3440 push_items * sizeof(struct btrfs_item));
3441
3442 /* update the item pointers */
3443 right_nritems += push_items;
3444 btrfs_set_header_nritems(right, right_nritems);
3445 push_space = BTRFS_LEAF_DATA_SIZE(root);
3446 for (i = 0; i < right_nritems; i++) {
3447 item = btrfs_item_nr(right, i);
3448 push_space -= btrfs_token_item_size(right, item, &token);
3449 btrfs_set_token_item_offset(right, item, push_space, &token);
3450 }
3451
3452 left_nritems -= push_items;
3453 btrfs_set_header_nritems(left, left_nritems);
3454
3455 if (left_nritems)
3456 btrfs_mark_buffer_dirty(left);
3457 else
3458 clean_tree_block(trans, root, left);
3459
3460 btrfs_mark_buffer_dirty(right);
3461
3462 btrfs_item_key(right, &disk_key, 0);
3463 btrfs_set_node_key(upper, &disk_key, slot + 1);
3464 btrfs_mark_buffer_dirty(upper);
3465
3466 /* then fixup the leaf pointer in the path */
3467 if (path->slots[0] >= left_nritems) {
3468 path->slots[0] -= left_nritems;
3469 if (btrfs_header_nritems(path->nodes[0]) == 0)
3470 clean_tree_block(trans, root, path->nodes[0]);
3471 btrfs_tree_unlock(path->nodes[0]);
3472 free_extent_buffer(path->nodes[0]);
3473 path->nodes[0] = right;
3474 path->slots[1] += 1;
3475 } else {
3476 btrfs_tree_unlock(right);
3477 free_extent_buffer(right);
3478 }
3479 return 0;
3480
3481 out_unlock:
3482 btrfs_tree_unlock(right);
3483 free_extent_buffer(right);
3484 return 1;
3485 }
3486
3487 /*
3488 * push some data in the path leaf to the right, trying to free up at
3489 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3490 *
3491 * returns 1 if the push failed because the other node didn't have enough
3492 * room, 0 if everything worked out and < 0 if there were major errors.
3493 *
3494 * this will push starting from min_slot to the end of the leaf. It won't
3495 * push any slot lower than min_slot
3496 */
3497 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
3498 *root, struct btrfs_path *path,
3499 int min_data_size, int data_size,
3500 int empty, u32 min_slot)
3501 {
3502 struct extent_buffer *left = path->nodes[0];
3503 struct extent_buffer *right;
3504 struct extent_buffer *upper;
3505 int slot;
3506 int free_space;
3507 u32 left_nritems;
3508 int ret;
3509
3510 if (!path->nodes[1])
3511 return 1;
3512
3513 slot = path->slots[1];
3514 upper = path->nodes[1];
3515 if (slot >= btrfs_header_nritems(upper) - 1)
3516 return 1;
3517
3518 btrfs_assert_tree_locked(path->nodes[1]);
3519
3520 right = read_node_slot(root, upper, slot + 1);
3521 if (right == NULL)
3522 return 1;
3523
3524 btrfs_tree_lock(right);
3525 btrfs_set_lock_blocking(right);
3526
3527 free_space = btrfs_leaf_free_space(root, right);
3528 if (free_space < data_size)
3529 goto out_unlock;
3530
3531 /* cow and double check */
3532 ret = btrfs_cow_block(trans, root, right, upper,
3533 slot + 1, &right);
3534 if (ret)
3535 goto out_unlock;
3536
3537 free_space = btrfs_leaf_free_space(root, right);
3538 if (free_space < data_size)
3539 goto out_unlock;
3540
3541 left_nritems = btrfs_header_nritems(left);
3542 if (left_nritems == 0)
3543 goto out_unlock;
3544
3545 return __push_leaf_right(trans, root, path, min_data_size, empty,
3546 right, free_space, left_nritems, min_slot);
3547 out_unlock:
3548 btrfs_tree_unlock(right);
3549 free_extent_buffer(right);
3550 return 1;
3551 }
3552
3553 /*
3554 * push some data in the path leaf to the left, trying to free up at
3555 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3556 *
3557 * max_slot can put a limit on how far into the leaf we'll push items. The
3558 * item at 'max_slot' won't be touched. Use (u32)-1 to make us do all the
3559 * items
3560 */
3561 static noinline int __push_leaf_left(struct btrfs_trans_handle *trans,
3562 struct btrfs_root *root,
3563 struct btrfs_path *path, int data_size,
3564 int empty, struct extent_buffer *left,
3565 int free_space, u32 right_nritems,
3566 u32 max_slot)
3567 {
3568 struct btrfs_disk_key disk_key;
3569 struct extent_buffer *right = path->nodes[0];
3570 int i;
3571 int push_space = 0;
3572 int push_items = 0;
3573 struct btrfs_item *item;
3574 u32 old_left_nritems;
3575 u32 nr;
3576 int ret = 0;
3577 u32 this_item_size;
3578 u32 old_left_item_size;
3579 struct btrfs_map_token token;
3580
3581 btrfs_init_map_token(&token);
3582
3583 if (empty)
3584 nr = min(right_nritems, max_slot);
3585 else
3586 nr = min(right_nritems - 1, max_slot);
3587
3588 for (i = 0; i < nr; i++) {
3589 item = btrfs_item_nr(right, i);
3590
3591 if (!empty && push_items > 0) {
3592 if (path->slots[0] < i)
3593 break;
3594 if (path->slots[0] == i) {
3595 int space = btrfs_leaf_free_space(root, right);
3596 if (space + push_space * 2 > free_space)
3597 break;
3598 }
3599 }
3600
3601 if (path->slots[0] == i)
3602 push_space += data_size;
3603
3604 this_item_size = btrfs_item_size(right, item);
3605 if (this_item_size + sizeof(*item) + push_space > free_space)
3606 break;
3607
3608 push_items++;
3609 push_space += this_item_size + sizeof(*item);
3610 }
3611
3612 if (push_items == 0) {
3613 ret = 1;
3614 goto out;
3615 }
3616 if (!empty && push_items == btrfs_header_nritems(right))
3617 WARN_ON(1);
3618
3619 /* push data from right to left */
3620 copy_extent_buffer(left, right,
3621 btrfs_item_nr_offset(btrfs_header_nritems(left)),
3622 btrfs_item_nr_offset(0),
3623 push_items * sizeof(struct btrfs_item));
3624
3625 push_space = BTRFS_LEAF_DATA_SIZE(root) -
3626 btrfs_item_offset_nr(right, push_items - 1);
3627
3628 copy_extent_buffer(left, right, btrfs_leaf_data(left) +
3629 leaf_data_end(root, left) - push_space,
3630 btrfs_leaf_data(right) +
3631 btrfs_item_offset_nr(right, push_items - 1),
3632 push_space);
3633 old_left_nritems = btrfs_header_nritems(left);
3634 BUG_ON(old_left_nritems <= 0);
3635
3636 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
3637 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
3638 u32 ioff;
3639
3640 item = btrfs_item_nr(left, i);
3641
3642 ioff = btrfs_token_item_offset(left, item, &token);
3643 btrfs_set_token_item_offset(left, item,
3644 ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size),
3645 &token);
3646 }
3647 btrfs_set_header_nritems(left, old_left_nritems + push_items);
3648
3649 /* fixup right node */
3650 if (push_items > right_nritems)
3651 WARN(1, KERN_CRIT "push items %d nr %u\n", push_items,
3652 right_nritems);
3653
3654 if (push_items < right_nritems) {
3655 push_space = btrfs_item_offset_nr(right, push_items - 1) -
3656 leaf_data_end(root, right);
3657 memmove_extent_buffer(right, btrfs_leaf_data(right) +
3658 BTRFS_LEAF_DATA_SIZE(root) - push_space,
3659 btrfs_leaf_data(right) +
3660 leaf_data_end(root, right), push_space);
3661
3662 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
3663 btrfs_item_nr_offset(push_items),
3664 (btrfs_header_nritems(right) - push_items) *
3665 sizeof(struct btrfs_item));
3666 }
3667 right_nritems -= push_items;
3668 btrfs_set_header_nritems(right, right_nritems);
3669 push_space = BTRFS_LEAF_DATA_SIZE(root);
3670 for (i = 0; i < right_nritems; i++) {
3671 item = btrfs_item_nr(right, i);
3672
3673 push_space = push_space - btrfs_token_item_size(right,
3674 item, &token);
3675 btrfs_set_token_item_offset(right, item, push_space, &token);
3676 }
3677
3678 btrfs_mark_buffer_dirty(left);
3679 if (right_nritems)
3680 btrfs_mark_buffer_dirty(right);
3681 else
3682 clean_tree_block(trans, root, right);
3683
3684 btrfs_item_key(right, &disk_key, 0);
3685 fixup_low_keys(trans, root, path, &disk_key, 1);
3686
3687 /* then fixup the leaf pointer in the path */
3688 if (path->slots[0] < push_items) {
3689 path->slots[0] += old_left_nritems;
3690 btrfs_tree_unlock(path->nodes[0]);
3691 free_extent_buffer(path->nodes[0]);
3692 path->nodes[0] = left;
3693 path->slots[1] -= 1;
3694 } else {
3695 btrfs_tree_unlock(left);
3696 free_extent_buffer(left);
3697 path->slots[0] -= push_items;
3698 }
3699 BUG_ON(path->slots[0] < 0);
3700 return ret;
3701 out:
3702 btrfs_tree_unlock(left);
3703 free_extent_buffer(left);
3704 return ret;
3705 }
3706
3707 /*
3708 * push some data in the path leaf to the left, trying to free up at
3709 * least data_size bytes. returns zero if the push worked, nonzero otherwise
3710 *
3711 * max_slot can put a limit on how far into the leaf we'll push items. The
3712 * item at 'max_slot' won't be touched. Use (u32)-1 to make us push all the
3713 * items
3714 */
3715 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
3716 *root, struct btrfs_path *path, int min_data_size,
3717 int data_size, int empty, u32 max_slot)
3718 {
3719 struct extent_buffer *right = path->nodes[0];
3720 struct extent_buffer *left;
3721 int slot;
3722 int free_space;
3723 u32 right_nritems;
3724 int ret = 0;
3725
3726 slot = path->slots[1];
3727 if (slot == 0)
3728 return 1;
3729 if (!path->nodes[1])
3730 return 1;
3731
3732 right_nritems = btrfs_header_nritems(right);
3733 if (right_nritems == 0)
3734 return 1;
3735
3736 btrfs_assert_tree_locked(path->nodes[1]);
3737
3738 left = read_node_slot(root, path->nodes[1], slot - 1);
3739 if (left == NULL)
3740 return 1;
3741
3742 btrfs_tree_lock(left);
3743 btrfs_set_lock_blocking(left);
3744
3745 free_space = btrfs_leaf_free_space(root, left);
3746 if (free_space < data_size) {
3747 ret = 1;
3748 goto out;
3749 }
3750
3751 /* cow and double check */
3752 ret = btrfs_cow_block(trans, root, left,
3753 path->nodes[1], slot - 1, &left);
3754 if (ret) {
3755 /* we hit -ENOSPC, but it isn't fatal here */
3756 if (ret == -ENOSPC)
3757 ret = 1;
3758 goto out;
3759 }
3760
3761 free_space = btrfs_leaf_free_space(root, left);
3762 if (free_space < data_size) {
3763 ret = 1;
3764 goto out;
3765 }
3766
3767 return __push_leaf_left(trans, root, path, min_data_size,
3768 empty, left, free_space, right_nritems,
3769 max_slot);
3770 out:
3771 btrfs_tree_unlock(left);
3772 free_extent_buffer(left);
3773 return ret;
3774 }
3775
3776 /*
3777 * split the path's leaf in two, making sure there is at least data_size
3778 * available for the resulting leaf level of the path.
3779 */
3780 static noinline void copy_for_split(struct btrfs_trans_handle *trans,
3781 struct btrfs_root *root,
3782 struct btrfs_path *path,
3783 struct extent_buffer *l,
3784 struct extent_buffer *right,
3785 int slot, int mid, int nritems)
3786 {
3787 int data_copy_size;
3788 int rt_data_off;
3789 int i;
3790 struct btrfs_disk_key disk_key;
3791 struct btrfs_map_token token;
3792
3793 btrfs_init_map_token(&token);
3794
3795 nritems = nritems - mid;
3796 btrfs_set_header_nritems(right, nritems);
3797 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
3798
3799 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
3800 btrfs_item_nr_offset(mid),
3801 nritems * sizeof(struct btrfs_item));
3802
3803 copy_extent_buffer(right, l,
3804 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
3805 data_copy_size, btrfs_leaf_data(l) +
3806 leaf_data_end(root, l), data_copy_size);
3807
3808 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
3809 btrfs_item_end_nr(l, mid);
3810
3811 for (i = 0; i < nritems; i++) {
3812 struct btrfs_item *item = btrfs_item_nr(right, i);
3813 u32 ioff;
3814
3815 ioff = btrfs_token_item_offset(right, item, &token);
3816 btrfs_set_token_item_offset(right, item,
3817 ioff + rt_data_off, &token);
3818 }
3819
3820 btrfs_set_header_nritems(l, mid);
3821 btrfs_item_key(right, &disk_key, 0);
3822 insert_ptr(trans, root, path, &disk_key, right->start,
3823 path->slots[1] + 1, 1);
3824
3825 btrfs_mark_buffer_dirty(right);
3826 btrfs_mark_buffer_dirty(l);
3827 BUG_ON(path->slots[0] != slot);
3828
3829 if (mid <= slot) {
3830 btrfs_tree_unlock(path->nodes[0]);
3831 free_extent_buffer(path->nodes[0]);
3832 path->nodes[0] = right;
3833 path->slots[0] -= mid;
3834 path->slots[1] += 1;
3835 } else {
3836 btrfs_tree_unlock(right);
3837 free_extent_buffer(right);
3838 }
3839
3840 BUG_ON(path->slots[0] < 0);
3841 }
3842
3843 /*
3844 * double splits happen when we need to insert a big item in the middle
3845 * of a leaf. A double split can leave us with 3 mostly empty leaves:
3846 * leaf: [ slots 0 - N] [ our target ] [ N + 1 - total in leaf ]
3847 * A B C
3848 *
3849 * We avoid this by trying to push the items on either side of our target
3850 * into the adjacent leaves. If all goes well we can avoid the double split
3851 * completely.
3852 */
3853 static noinline int push_for_double_split(struct btrfs_trans_handle *trans,
3854 struct btrfs_root *root,
3855 struct btrfs_path *path,
3856 int data_size)
3857 {
3858 int ret;
3859 int progress = 0;
3860 int slot;
3861 u32 nritems;
3862
3863 slot = path->slots[0];
3864
3865 /*
3866 * try to push all the items after our slot into the
3867 * right leaf
3868 */
3869 ret = push_leaf_right(trans, root, path, 1, data_size, 0, slot);
3870 if (ret < 0)
3871 return ret;
3872
3873 if (ret == 0)
3874 progress++;
3875
3876 nritems = btrfs_header_nritems(path->nodes[0]);
3877 /*
3878 * our goal is to get our slot at the start or end of a leaf. If
3879 * we've done so we're done
3880 */
3881 if (path->slots[0] == 0 || path->slots[0] == nritems)
3882 return 0;
3883
3884 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
3885 return 0;
3886
3887 /* try to push all the items before our slot into the next leaf */
3888 slot = path->slots[0];
3889 ret = push_leaf_left(trans, root, path, 1, data_size, 0, slot);
3890 if (ret < 0)
3891 return ret;
3892
3893 if (ret == 0)
3894 progress++;
3895
3896 if (progress)
3897 return 0;
3898 return 1;
3899 }
3900
3901 /*
3902 * split the path's leaf in two, making sure there is at least data_size
3903 * available for the resulting leaf level of the path.
3904 *
3905 * returns 0 if all went well and < 0 on failure.
3906 */
3907 static noinline int split_leaf(struct btrfs_trans_handle *trans,
3908 struct btrfs_root *root,
3909 struct btrfs_key *ins_key,
3910 struct btrfs_path *path, int data_size,
3911 int extend)
3912 {
3913 struct btrfs_disk_key disk_key;
3914 struct extent_buffer *l;
3915 u32 nritems;
3916 int mid;
3917 int slot;
3918 struct extent_buffer *right;
3919 int ret = 0;
3920 int wret;
3921 int split;
3922 int num_doubles = 0;
3923 int tried_avoid_double = 0;
3924
3925 l = path->nodes[0];
3926 slot = path->slots[0];
3927 if (extend && data_size + btrfs_item_size_nr(l, slot) +
3928 sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root))
3929 return -EOVERFLOW;
3930
3931 /* first try to make some room by pushing left and right */
3932 if (data_size) {
3933 wret = push_leaf_right(trans, root, path, data_size,
3934 data_size, 0, 0);
3935 if (wret < 0)
3936 return wret;
3937 if (wret) {
3938 wret = push_leaf_left(trans, root, path, data_size,
3939 data_size, 0, (u32)-1);
3940 if (wret < 0)
3941 return wret;
3942 }
3943 l = path->nodes[0];
3944
3945 /* did the pushes work? */
3946 if (btrfs_leaf_free_space(root, l) >= data_size)
3947 return 0;
3948 }
3949
3950 if (!path->nodes[1]) {
3951 ret = insert_new_root(trans, root, path, 1);
3952 if (ret)
3953 return ret;
3954 }
3955 again:
3956 split = 1;
3957 l = path->nodes[0];
3958 slot = path->slots[0];
3959 nritems = btrfs_header_nritems(l);
3960 mid = (nritems + 1) / 2;
3961
3962 if (mid <= slot) {
3963 if (nritems == 1 ||
3964 leaf_space_used(l, mid, nritems - mid) + data_size >
3965 BTRFS_LEAF_DATA_SIZE(root)) {
3966 if (slot >= nritems) {
3967 split = 0;
3968 } else {
3969 mid = slot;
3970 if (mid != nritems &&
3971 leaf_space_used(l, mid, nritems - mid) +
3972 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3973 if (data_size && !tried_avoid_double)
3974 goto push_for_double;
3975 split = 2;
3976 }
3977 }
3978 }
3979 } else {
3980 if (leaf_space_used(l, 0, mid) + data_size >
3981 BTRFS_LEAF_DATA_SIZE(root)) {
3982 if (!extend && data_size && slot == 0) {
3983 split = 0;
3984 } else if ((extend || !data_size) && slot == 0) {
3985 mid = 1;
3986 } else {
3987 mid = slot;
3988 if (mid != nritems &&
3989 leaf_space_used(l, mid, nritems - mid) +
3990 data_size > BTRFS_LEAF_DATA_SIZE(root)) {
3991 if (data_size && !tried_avoid_double)
3992 goto push_for_double;
3993 split = 2 ;
3994 }
3995 }
3996 }
3997 }
3998
3999 if (split == 0)
4000 btrfs_cpu_key_to_disk(&disk_key, ins_key);
4001 else
4002 btrfs_item_key(l, &disk_key, mid);
4003
4004 right = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
4005 root->root_key.objectid,
4006 &disk_key, 0, l->start, 0);
4007 if (IS_ERR(right))
4008 return PTR_ERR(right);
4009
4010 root_add_used(root, root->leafsize);
4011
4012 memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
4013 btrfs_set_header_bytenr(right, right->start);
4014 btrfs_set_header_generation(right, trans->transid);
4015 btrfs_set_header_backref_rev(right, BTRFS_MIXED_BACKREF_REV);
4016 btrfs_set_header_owner(right, root->root_key.objectid);
4017 btrfs_set_header_level(right, 0);
4018 write_extent_buffer(right, root->fs_info->fsid,
4019 (unsigned long)btrfs_header_fsid(right),
4020 BTRFS_FSID_SIZE);
4021
4022 write_extent_buffer(right, root->fs_info->chunk_tree_uuid,
4023 (unsigned long)btrfs_header_chunk_tree_uuid(right),
4024 BTRFS_UUID_SIZE);
4025
4026 if (split == 0) {
4027 if (mid <= slot) {
4028 btrfs_set_header_nritems(right, 0);
4029 insert_ptr(trans, root, path, &disk_key, right->start,
4030 path->slots[1] + 1, 1);
4031 btrfs_tree_unlock(path->nodes[0]);
4032 free_extent_buffer(path->nodes[0]);
4033 path->nodes[0] = right;
4034 path->slots[0] = 0;
4035 path->slots[1] += 1;
4036 } else {
4037 btrfs_set_header_nritems(right, 0);
4038 insert_ptr(trans, root, path, &disk_key, right->start,
4039 path->slots[1], 1);
4040 btrfs_tree_unlock(path->nodes[0]);
4041 free_extent_buffer(path->nodes[0]);
4042 path->nodes[0] = right;
4043 path->slots[0] = 0;
4044 if (path->slots[1] == 0)
4045 fixup_low_keys(trans, root, path,
4046 &disk_key, 1);
4047 }
4048 btrfs_mark_buffer_dirty(right);
4049 return ret;
4050 }
4051
4052 copy_for_split(trans, root, path, l, right, slot, mid, nritems);
4053
4054 if (split == 2) {
4055 BUG_ON(num_doubles != 0);
4056 num_doubles++;
4057 goto again;
4058 }
4059
4060 return 0;
4061
4062 push_for_double:
4063 push_for_double_split(trans, root, path, data_size);
4064 tried_avoid_double = 1;
4065 if (btrfs_leaf_free_space(root, path->nodes[0]) >= data_size)
4066 return 0;
4067 goto again;
4068 }
4069
4070 static noinline int setup_leaf_for_split(struct btrfs_trans_handle *trans,
4071 struct btrfs_root *root,
4072 struct btrfs_path *path, int ins_len)
4073 {
4074 struct btrfs_key key;
4075 struct extent_buffer *leaf;
4076 struct btrfs_file_extent_item *fi;
4077 u64 extent_len = 0;
4078 u32 item_size;
4079 int ret;
4080
4081 leaf = path->nodes[0];
4082 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
4083
4084 BUG_ON(key.type != BTRFS_EXTENT_DATA_KEY &&
4085 key.type != BTRFS_EXTENT_CSUM_KEY);
4086
4087 if (btrfs_leaf_free_space(root, leaf) >= ins_len)
4088 return 0;
4089
4090 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4091 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4092 fi = btrfs_item_ptr(leaf, path->slots[0],
4093 struct btrfs_file_extent_item);
4094 extent_len = btrfs_file_extent_num_bytes(leaf, fi);
4095 }
4096 btrfs_release_path(path);
4097
4098 path->keep_locks = 1;
4099 path->search_for_split = 1;
4100 ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
4101 path->search_for_split = 0;
4102 if (ret < 0)
4103 goto err;
4104
4105 ret = -EAGAIN;
4106 leaf = path->nodes[0];
4107 /* if our item isn't there or got smaller, return now */
4108 if (ret > 0 || item_size != btrfs_item_size_nr(leaf, path->slots[0]))
4109 goto err;
4110
4111 /* the leaf has changed, it now has room. return now */
4112 if (btrfs_leaf_free_space(root, path->nodes[0]) >= ins_len)
4113 goto err;
4114
4115 if (key.type == BTRFS_EXTENT_DATA_KEY) {
4116 fi = btrfs_item_ptr(leaf, path->slots[0],
4117 struct btrfs_file_extent_item);
4118 if (extent_len != btrfs_file_extent_num_bytes(leaf, fi))
4119 goto err;
4120 }
4121
4122 btrfs_set_path_blocking(path);
4123 ret = split_leaf(trans, root, &key, path, ins_len, 1);
4124 if (ret)
4125 goto err;
4126
4127 path->keep_locks = 0;
4128 btrfs_unlock_up_safe(path, 1);
4129 return 0;
4130 err:
4131 path->keep_locks = 0;
4132 return ret;
4133 }
4134
4135 static noinline int split_item(struct btrfs_trans_handle *trans,
4136 struct btrfs_root *root,
4137 struct btrfs_path *path,
4138 struct btrfs_key *new_key,
4139 unsigned long split_offset)
4140 {
4141 struct extent_buffer *leaf;
4142 struct btrfs_item *item;
4143 struct btrfs_item *new_item;
4144 int slot;
4145 char *buf;
4146 u32 nritems;
4147 u32 item_size;
4148 u32 orig_offset;
4149 struct btrfs_disk_key disk_key;
4150
4151 leaf = path->nodes[0];
4152 BUG_ON(btrfs_leaf_free_space(root, leaf) < sizeof(struct btrfs_item));
4153
4154 btrfs_set_path_blocking(path);
4155
4156 item = btrfs_item_nr(leaf, path->slots[0]);
4157 orig_offset = btrfs_item_offset(leaf, item);
4158 item_size = btrfs_item_size(leaf, item);
4159
4160 buf = kmalloc(item_size, GFP_NOFS);
4161 if (!buf)
4162 return -ENOMEM;
4163
4164 read_extent_buffer(leaf, buf, btrfs_item_ptr_offset(leaf,
4165 path->slots[0]), item_size);
4166
4167 slot = path->slots[0] + 1;
4168 nritems = btrfs_header_nritems(leaf);
4169 if (slot != nritems) {
4170 /* shift the items */
4171 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + 1),
4172 btrfs_item_nr_offset(slot),
4173 (nritems - slot) * sizeof(struct btrfs_item));
4174 }
4175
4176 btrfs_cpu_key_to_disk(&disk_key, new_key);
4177 btrfs_set_item_key(leaf, &disk_key, slot);
4178
4179 new_item = btrfs_item_nr(leaf, slot);
4180
4181 btrfs_set_item_offset(leaf, new_item, orig_offset);
4182 btrfs_set_item_size(leaf, new_item, item_size - split_offset);
4183
4184 btrfs_set_item_offset(leaf, item,
4185 orig_offset + item_size - split_offset);
4186 btrfs_set_item_size(leaf, item, split_offset);
4187
4188 btrfs_set_header_nritems(leaf, nritems + 1);
4189
4190 /* write the data for the start of the original item */
4191 write_extent_buffer(leaf, buf,
4192 btrfs_item_ptr_offset(leaf, path->slots[0]),
4193 split_offset);
4194
4195 /* write the data for the new item */
4196 write_extent_buffer(leaf, buf + split_offset,
4197 btrfs_item_ptr_offset(leaf, slot),
4198 item_size - split_offset);
4199 btrfs_mark_buffer_dirty(leaf);
4200
4201 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
4202 kfree(buf);
4203 return 0;
4204 }
4205
4206 /*
4207 * This function splits a single item into two items,
4208 * giving 'new_key' to the new item and splitting the
4209 * old one at split_offset (from the start of the item).
4210 *
4211 * The path may be released by this operation. After
4212 * the split, the path is pointing to the old item. The
4213 * new item is going to be in the same node as the old one.
4214 *
4215 * Note, the item being split must be smaller enough to live alone on
4216 * a tree block with room for one extra struct btrfs_item
4217 *
4218 * This allows us to split the item in place, keeping a lock on the
4219 * leaf the entire time.
4220 */
4221 int btrfs_split_item(struct btrfs_trans_handle *trans,
4222 struct btrfs_root *root,
4223 struct btrfs_path *path,
4224 struct btrfs_key *new_key,
4225 unsigned long split_offset)
4226 {
4227 int ret;
4228 ret = setup_leaf_for_split(trans, root, path,
4229 sizeof(struct btrfs_item));
4230 if (ret)
4231 return ret;
4232
4233 ret = split_item(trans, root, path, new_key, split_offset);
4234 return ret;
4235 }
4236
4237 /*
4238 * This function duplicate a item, giving 'new_key' to the new item.
4239 * It guarantees both items live in the same tree leaf and the new item
4240 * is contiguous with the original item.
4241 *
4242 * This allows us to split file extent in place, keeping a lock on the
4243 * leaf the entire time.
4244 */
4245 int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
4246 struct btrfs_root *root,
4247 struct btrfs_path *path,
4248 struct btrfs_key *new_key)
4249 {
4250 struct extent_buffer *leaf;
4251 int ret;
4252 u32 item_size;
4253
4254 leaf = path->nodes[0];
4255 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
4256 ret = setup_leaf_for_split(trans, root, path,
4257 item_size + sizeof(struct btrfs_item));
4258 if (ret)
4259 return ret;
4260
4261 path->slots[0]++;
4262 setup_items_for_insert(trans, root, path, new_key, &item_size,
4263 item_size, item_size +
4264 sizeof(struct btrfs_item), 1);
4265 leaf = path->nodes[0];
4266 memcpy_extent_buffer(leaf,
4267 btrfs_item_ptr_offset(leaf, path->slots[0]),
4268 btrfs_item_ptr_offset(leaf, path->slots[0] - 1),
4269 item_size);
4270 return 0;
4271 }
4272
4273 /*
4274 * make the item pointed to by the path smaller. new_size indicates
4275 * how small to make it, and from_end tells us if we just chop bytes
4276 * off the end of the item or if we shift the item to chop bytes off
4277 * the front.
4278 */
4279 void btrfs_truncate_item(struct btrfs_trans_handle *trans,
4280 struct btrfs_root *root,
4281 struct btrfs_path *path,
4282 u32 new_size, int from_end)
4283 {
4284 int slot;
4285 struct extent_buffer *leaf;
4286 struct btrfs_item *item;
4287 u32 nritems;
4288 unsigned int data_end;
4289 unsigned int old_data_start;
4290 unsigned int old_size;
4291 unsigned int size_diff;
4292 int i;
4293 struct btrfs_map_token token;
4294
4295 btrfs_init_map_token(&token);
4296
4297 leaf = path->nodes[0];
4298 slot = path->slots[0];
4299
4300 old_size = btrfs_item_size_nr(leaf, slot);
4301 if (old_size == new_size)
4302 return;
4303
4304 nritems = btrfs_header_nritems(leaf);
4305 data_end = leaf_data_end(root, leaf);
4306
4307 old_data_start = btrfs_item_offset_nr(leaf, slot);
4308
4309 size_diff = old_size - new_size;
4310
4311 BUG_ON(slot < 0);
4312 BUG_ON(slot >= nritems);
4313
4314 /*
4315 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4316 */
4317 /* first correct the data pointers */
4318 for (i = slot; i < nritems; i++) {
4319 u32 ioff;
4320 item = btrfs_item_nr(leaf, i);
4321
4322 ioff = btrfs_token_item_offset(leaf, item, &token);
4323 btrfs_set_token_item_offset(leaf, item,
4324 ioff + size_diff, &token);
4325 }
4326
4327 /* shift the data */
4328 if (from_end) {
4329 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4330 data_end + size_diff, btrfs_leaf_data(leaf) +
4331 data_end, old_data_start + new_size - data_end);
4332 } else {
4333 struct btrfs_disk_key disk_key;
4334 u64 offset;
4335
4336 btrfs_item_key(leaf, &disk_key, slot);
4337
4338 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
4339 unsigned long ptr;
4340 struct btrfs_file_extent_item *fi;
4341
4342 fi = btrfs_item_ptr(leaf, slot,
4343 struct btrfs_file_extent_item);
4344 fi = (struct btrfs_file_extent_item *)(
4345 (unsigned long)fi - size_diff);
4346
4347 if (btrfs_file_extent_type(leaf, fi) ==
4348 BTRFS_FILE_EXTENT_INLINE) {
4349 ptr = btrfs_item_ptr_offset(leaf, slot);
4350 memmove_extent_buffer(leaf, ptr,
4351 (unsigned long)fi,
4352 offsetof(struct btrfs_file_extent_item,
4353 disk_bytenr));
4354 }
4355 }
4356
4357 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4358 data_end + size_diff, btrfs_leaf_data(leaf) +
4359 data_end, old_data_start - data_end);
4360
4361 offset = btrfs_disk_key_offset(&disk_key);
4362 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
4363 btrfs_set_item_key(leaf, &disk_key, slot);
4364 if (slot == 0)
4365 fixup_low_keys(trans, root, path, &disk_key, 1);
4366 }
4367
4368 item = btrfs_item_nr(leaf, slot);
4369 btrfs_set_item_size(leaf, item, new_size);
4370 btrfs_mark_buffer_dirty(leaf);
4371
4372 if (btrfs_leaf_free_space(root, leaf) < 0) {
4373 btrfs_print_leaf(root, leaf);
4374 BUG();
4375 }
4376 }
4377
4378 /*
4379 * make the item pointed to by the path bigger, data_size is the new size.
4380 */
4381 void btrfs_extend_item(struct btrfs_trans_handle *trans,
4382 struct btrfs_root *root, struct btrfs_path *path,
4383 u32 data_size)
4384 {
4385 int slot;
4386 struct extent_buffer *leaf;
4387 struct btrfs_item *item;
4388 u32 nritems;
4389 unsigned int data_end;
4390 unsigned int old_data;
4391 unsigned int old_size;
4392 int i;
4393 struct btrfs_map_token token;
4394
4395 btrfs_init_map_token(&token);
4396
4397 leaf = path->nodes[0];
4398
4399 nritems = btrfs_header_nritems(leaf);
4400 data_end = leaf_data_end(root, leaf);
4401
4402 if (btrfs_leaf_free_space(root, leaf) < data_size) {
4403 btrfs_print_leaf(root, leaf);
4404 BUG();
4405 }
4406 slot = path->slots[0];
4407 old_data = btrfs_item_end_nr(leaf, slot);
4408
4409 BUG_ON(slot < 0);
4410 if (slot >= nritems) {
4411 btrfs_print_leaf(root, leaf);
4412 printk(KERN_CRIT "slot %d too large, nritems %d\n",
4413 slot, nritems);
4414 BUG_ON(1);
4415 }
4416
4417 /*
4418 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4419 */
4420 /* first correct the data pointers */
4421 for (i = slot; i < nritems; i++) {
4422 u32 ioff;
4423 item = btrfs_item_nr(leaf, i);
4424
4425 ioff = btrfs_token_item_offset(leaf, item, &token);
4426 btrfs_set_token_item_offset(leaf, item,
4427 ioff - data_size, &token);
4428 }
4429
4430 /* shift the data */
4431 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4432 data_end - data_size, btrfs_leaf_data(leaf) +
4433 data_end, old_data - data_end);
4434
4435 data_end = old_data;
4436 old_size = btrfs_item_size_nr(leaf, slot);
4437 item = btrfs_item_nr(leaf, slot);
4438 btrfs_set_item_size(leaf, item, old_size + data_size);
4439 btrfs_mark_buffer_dirty(leaf);
4440
4441 if (btrfs_leaf_free_space(root, leaf) < 0) {
4442 btrfs_print_leaf(root, leaf);
4443 BUG();
4444 }
4445 }
4446
4447 /*
4448 * this is a helper for btrfs_insert_empty_items, the main goal here is
4449 * to save stack depth by doing the bulk of the work in a function
4450 * that doesn't call btrfs_search_slot
4451 */
4452 void setup_items_for_insert(struct btrfs_trans_handle *trans,
4453 struct btrfs_root *root, struct btrfs_path *path,
4454 struct btrfs_key *cpu_key, u32 *data_size,
4455 u32 total_data, u32 total_size, int nr)
4456 {
4457 struct btrfs_item *item;
4458 int i;
4459 u32 nritems;
4460 unsigned int data_end;
4461 struct btrfs_disk_key disk_key;
4462 struct extent_buffer *leaf;
4463 int slot;
4464 struct btrfs_map_token token;
4465
4466 btrfs_init_map_token(&token);
4467
4468 leaf = path->nodes[0];
4469 slot = path->slots[0];
4470
4471 nritems = btrfs_header_nritems(leaf);
4472 data_end = leaf_data_end(root, leaf);
4473
4474 if (btrfs_leaf_free_space(root, leaf) < total_size) {
4475 btrfs_print_leaf(root, leaf);
4476 printk(KERN_CRIT "not enough freespace need %u have %d\n",
4477 total_size, btrfs_leaf_free_space(root, leaf));
4478 BUG();
4479 }
4480
4481 if (slot != nritems) {
4482 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
4483
4484 if (old_data < data_end) {
4485 btrfs_print_leaf(root, leaf);
4486 printk(KERN_CRIT "slot %d old_data %d data_end %d\n",
4487 slot, old_data, data_end);
4488 BUG_ON(1);
4489 }
4490 /*
4491 * item0..itemN ... dataN.offset..dataN.size .. data0.size
4492 */
4493 /* first correct the data pointers */
4494 for (i = slot; i < nritems; i++) {
4495 u32 ioff;
4496
4497 item = btrfs_item_nr(leaf, i);
4498 ioff = btrfs_token_item_offset(leaf, item, &token);
4499 btrfs_set_token_item_offset(leaf, item,
4500 ioff - total_data, &token);
4501 }
4502 /* shift the items */
4503 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
4504 btrfs_item_nr_offset(slot),
4505 (nritems - slot) * sizeof(struct btrfs_item));
4506
4507 /* shift the data */
4508 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4509 data_end - total_data, btrfs_leaf_data(leaf) +
4510 data_end, old_data - data_end);
4511 data_end = old_data;
4512 }
4513
4514 /* setup the item for the new data */
4515 for (i = 0; i < nr; i++) {
4516 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
4517 btrfs_set_item_key(leaf, &disk_key, slot + i);
4518 item = btrfs_item_nr(leaf, slot + i);
4519 btrfs_set_token_item_offset(leaf, item,
4520 data_end - data_size[i], &token);
4521 data_end -= data_size[i];
4522 btrfs_set_token_item_size(leaf, item, data_size[i], &token);
4523 }
4524
4525 btrfs_set_header_nritems(leaf, nritems + nr);
4526
4527 if (slot == 0) {
4528 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
4529 fixup_low_keys(trans, root, path, &disk_key, 1);
4530 }
4531 btrfs_unlock_up_safe(path, 1);
4532 btrfs_mark_buffer_dirty(leaf);
4533
4534 if (btrfs_leaf_free_space(root, leaf) < 0) {
4535 btrfs_print_leaf(root, leaf);
4536 BUG();
4537 }
4538 }
4539
4540 /*
4541 * Given a key and some data, insert items into the tree.
4542 * This does all the path init required, making room in the tree if needed.
4543 */
4544 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
4545 struct btrfs_root *root,
4546 struct btrfs_path *path,
4547 struct btrfs_key *cpu_key, u32 *data_size,
4548 int nr)
4549 {
4550 int ret = 0;
4551 int slot;
4552 int i;
4553 u32 total_size = 0;
4554 u32 total_data = 0;
4555
4556 for (i = 0; i < nr; i++)
4557 total_data += data_size[i];
4558
4559 total_size = total_data + (nr * sizeof(struct btrfs_item));
4560 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
4561 if (ret == 0)
4562 return -EEXIST;
4563 if (ret < 0)
4564 return ret;
4565
4566 slot = path->slots[0];
4567 BUG_ON(slot < 0);
4568
4569 setup_items_for_insert(trans, root, path, cpu_key, data_size,
4570 total_data, total_size, nr);
4571 return 0;
4572 }
4573
4574 /*
4575 * Given a key and some data, insert an item into the tree.
4576 * This does all the path init required, making room in the tree if needed.
4577 */
4578 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
4579 *root, struct btrfs_key *cpu_key, void *data, u32
4580 data_size)
4581 {
4582 int ret = 0;
4583 struct btrfs_path *path;
4584 struct extent_buffer *leaf;
4585 unsigned long ptr;
4586
4587 path = btrfs_alloc_path();
4588 if (!path)
4589 return -ENOMEM;
4590 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
4591 if (!ret) {
4592 leaf = path->nodes[0];
4593 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
4594 write_extent_buffer(leaf, data, ptr, data_size);
4595 btrfs_mark_buffer_dirty(leaf);
4596 }
4597 btrfs_free_path(path);
4598 return ret;
4599 }
4600
4601 /*
4602 * delete the pointer from a given node.
4603 *
4604 * the tree should have been previously balanced so the deletion does not
4605 * empty a node.
4606 */
4607 static void del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4608 struct btrfs_path *path, int level, int slot)
4609 {
4610 struct extent_buffer *parent = path->nodes[level];
4611 u32 nritems;
4612 int ret;
4613
4614 if (level) {
4615 ret = tree_mod_log_insert_key(root->fs_info, parent, slot,
4616 MOD_LOG_KEY_REMOVE);
4617 BUG_ON(ret < 0);
4618 }
4619
4620 nritems = btrfs_header_nritems(parent);
4621 if (slot != nritems - 1) {
4622 if (level)
4623 tree_mod_log_eb_move(root->fs_info, parent, slot,
4624 slot + 1, nritems - slot - 1);
4625 memmove_extent_buffer(parent,
4626 btrfs_node_key_ptr_offset(slot),
4627 btrfs_node_key_ptr_offset(slot + 1),
4628 sizeof(struct btrfs_key_ptr) *
4629 (nritems - slot - 1));
4630 }
4631
4632 nritems--;
4633 btrfs_set_header_nritems(parent, nritems);
4634 if (nritems == 0 && parent == root->node) {
4635 BUG_ON(btrfs_header_level(root->node) != 1);
4636 /* just turn the root into a leaf and break */
4637 btrfs_set_header_level(root->node, 0);
4638 } else if (slot == 0) {
4639 struct btrfs_disk_key disk_key;
4640
4641 btrfs_node_key(parent, &disk_key, 0);
4642 fixup_low_keys(trans, root, path, &disk_key, level + 1);
4643 }
4644 btrfs_mark_buffer_dirty(parent);
4645 }
4646
4647 /*
4648 * a helper function to delete the leaf pointed to by path->slots[1] and
4649 * path->nodes[1].
4650 *
4651 * This deletes the pointer in path->nodes[1] and frees the leaf
4652 * block extent. zero is returned if it all worked out, < 0 otherwise.
4653 *
4654 * The path must have already been setup for deleting the leaf, including
4655 * all the proper balancing. path->nodes[1] must be locked.
4656 */
4657 static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
4658 struct btrfs_root *root,
4659 struct btrfs_path *path,
4660 struct extent_buffer *leaf)
4661 {
4662 WARN_ON(btrfs_header_generation(leaf) != trans->transid);
4663 del_ptr(trans, root, path, 1, path->slots[1]);
4664
4665 /*
4666 * btrfs_free_extent is expensive, we want to make sure we
4667 * aren't holding any locks when we call it
4668 */
4669 btrfs_unlock_up_safe(path, 0);
4670
4671 root_sub_used(root, leaf->len);
4672
4673 extent_buffer_get(leaf);
4674 btrfs_free_tree_block(trans, root, leaf, 0, 1);
4675 free_extent_buffer_stale(leaf);
4676 }
4677 /*
4678 * delete the item at the leaf level in path. If that empties
4679 * the leaf, remove it from the tree
4680 */
4681 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
4682 struct btrfs_path *path, int slot, int nr)
4683 {
4684 struct extent_buffer *leaf;
4685 struct btrfs_item *item;
4686 int last_off;
4687 int dsize = 0;
4688 int ret = 0;
4689 int wret;
4690 int i;
4691 u32 nritems;
4692 struct btrfs_map_token token;
4693
4694 btrfs_init_map_token(&token);
4695
4696 leaf = path->nodes[0];
4697 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
4698
4699 for (i = 0; i < nr; i++)
4700 dsize += btrfs_item_size_nr(leaf, slot + i);
4701
4702 nritems = btrfs_header_nritems(leaf);
4703
4704 if (slot + nr != nritems) {
4705 int data_end = leaf_data_end(root, leaf);
4706
4707 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
4708 data_end + dsize,
4709 btrfs_leaf_data(leaf) + data_end,
4710 last_off - data_end);
4711
4712 for (i = slot + nr; i < nritems; i++) {
4713 u32 ioff;
4714
4715 item = btrfs_item_nr(leaf, i);
4716 ioff = btrfs_token_item_offset(leaf, item, &token);
4717 btrfs_set_token_item_offset(leaf, item,
4718 ioff + dsize, &token);
4719 }
4720
4721 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
4722 btrfs_item_nr_offset(slot + nr),
4723 sizeof(struct btrfs_item) *
4724 (nritems - slot - nr));
4725 }
4726 btrfs_set_header_nritems(leaf, nritems - nr);
4727 nritems -= nr;
4728
4729 /* delete the leaf if we've emptied it */
4730 if (nritems == 0) {
4731 if (leaf == root->node) {
4732 btrfs_set_header_level(leaf, 0);
4733 } else {
4734 btrfs_set_path_blocking(path);
4735 clean_tree_block(trans, root, leaf);
4736 btrfs_del_leaf(trans, root, path, leaf);
4737 }
4738 } else {
4739 int used = leaf_space_used(leaf, 0, nritems);
4740 if (slot == 0) {
4741 struct btrfs_disk_key disk_key;
4742
4743 btrfs_item_key(leaf, &disk_key, 0);
4744 fixup_low_keys(trans, root, path, &disk_key, 1);
4745 }
4746
4747 /* delete the leaf if it is mostly empty */
4748 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
4749 /* push_leaf_left fixes the path.
4750 * make sure the path still points to our leaf
4751 * for possible call to del_ptr below
4752 */
4753 slot = path->slots[1];
4754 extent_buffer_get(leaf);
4755
4756 btrfs_set_path_blocking(path);
4757 wret = push_leaf_left(trans, root, path, 1, 1,
4758 1, (u32)-1);
4759 if (wret < 0 && wret != -ENOSPC)
4760 ret = wret;
4761
4762 if (path->nodes[0] == leaf &&
4763 btrfs_header_nritems(leaf)) {
4764 wret = push_leaf_right(trans, root, path, 1,
4765 1, 1, 0);
4766 if (wret < 0 && wret != -ENOSPC)
4767 ret = wret;
4768 }
4769
4770 if (btrfs_header_nritems(leaf) == 0) {
4771 path->slots[1] = slot;
4772 btrfs_del_leaf(trans, root, path, leaf);
4773 free_extent_buffer(leaf);
4774 ret = 0;
4775 } else {
4776 /* if we're still in the path, make sure
4777 * we're dirty. Otherwise, one of the
4778 * push_leaf functions must have already
4779 * dirtied this buffer
4780 */
4781 if (path->nodes[0] == leaf)
4782 btrfs_mark_buffer_dirty(leaf);
4783 free_extent_buffer(leaf);
4784 }
4785 } else {
4786 btrfs_mark_buffer_dirty(leaf);
4787 }
4788 }
4789 return ret;
4790 }
4791
4792 /*
4793 * search the tree again to find a leaf with lesser keys
4794 * returns 0 if it found something or 1 if there are no lesser leaves.
4795 * returns < 0 on io errors.
4796 *
4797 * This may release the path, and so you may lose any locks held at the
4798 * time you call it.
4799 */
4800 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
4801 {
4802 struct btrfs_key key;
4803 struct btrfs_disk_key found_key;
4804 int ret;
4805
4806 btrfs_item_key_to_cpu(path->nodes[0], &key, 0);
4807
4808 if (key.offset > 0)
4809 key.offset--;
4810 else if (key.type > 0)
4811 key.type--;
4812 else if (key.objectid > 0)
4813 key.objectid--;
4814 else
4815 return 1;
4816
4817 btrfs_release_path(path);
4818 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
4819 if (ret < 0)
4820 return ret;
4821 btrfs_item_key(path->nodes[0], &found_key, 0);
4822 ret = comp_keys(&found_key, &key);
4823 if (ret < 0)
4824 return 0;
4825 return 1;
4826 }
4827
4828 /*
4829 * A helper function to walk down the tree starting at min_key, and looking
4830 * for nodes or leaves that are either in cache or have a minimum
4831 * transaction id. This is used by the btree defrag code, and tree logging
4832 *
4833 * This does not cow, but it does stuff the starting key it finds back
4834 * into min_key, so you can call btrfs_search_slot with cow=1 on the
4835 * key and get a writable path.
4836 *
4837 * This does lock as it descends, and path->keep_locks should be set
4838 * to 1 by the caller.
4839 *
4840 * This honors path->lowest_level to prevent descent past a given level
4841 * of the tree.
4842 *
4843 * min_trans indicates the oldest transaction that you are interested
4844 * in walking through. Any nodes or leaves older than min_trans are
4845 * skipped over (without reading them).
4846 *
4847 * returns zero if something useful was found, < 0 on error and 1 if there
4848 * was nothing in the tree that matched the search criteria.
4849 */
4850 int btrfs_search_forward(struct btrfs_root *root, struct btrfs_key *min_key,
4851 struct btrfs_key *max_key,
4852 struct btrfs_path *path, int cache_only,
4853 u64 min_trans)
4854 {
4855 struct extent_buffer *cur;
4856 struct btrfs_key found_key;
4857 int slot;
4858 int sret;
4859 u32 nritems;
4860 int level;
4861 int ret = 1;
4862
4863 WARN_ON(!path->keep_locks);
4864 again:
4865 cur = btrfs_read_lock_root_node(root);
4866 level = btrfs_header_level(cur);
4867 WARN_ON(path->nodes[level]);
4868 path->nodes[level] = cur;
4869 path->locks[level] = BTRFS_READ_LOCK;
4870
4871 if (btrfs_header_generation(cur) < min_trans) {
4872 ret = 1;
4873 goto out;
4874 }
4875 while (1) {
4876 nritems = btrfs_header_nritems(cur);
4877 level = btrfs_header_level(cur);
4878 sret = bin_search(cur, min_key, level, &slot);
4879
4880 /* at the lowest level, we're done, setup the path and exit */
4881 if (level == path->lowest_level) {
4882 if (slot >= nritems)
4883 goto find_next_key;
4884 ret = 0;
4885 path->slots[level] = slot;
4886 btrfs_item_key_to_cpu(cur, &found_key, slot);
4887 goto out;
4888 }
4889 if (sret && slot > 0)
4890 slot--;
4891 /*
4892 * check this node pointer against the cache_only and
4893 * min_trans parameters. If it isn't in cache or is too
4894 * old, skip to the next one.
4895 */
4896 while (slot < nritems) {
4897 u64 blockptr;
4898 u64 gen;
4899 struct extent_buffer *tmp;
4900 struct btrfs_disk_key disk_key;
4901
4902 blockptr = btrfs_node_blockptr(cur, slot);
4903 gen = btrfs_node_ptr_generation(cur, slot);
4904 if (gen < min_trans) {
4905 slot++;
4906 continue;
4907 }
4908 if (!cache_only)
4909 break;
4910
4911 if (max_key) {
4912 btrfs_node_key(cur, &disk_key, slot);
4913 if (comp_keys(&disk_key, max_key) >= 0) {
4914 ret = 1;
4915 goto out;
4916 }
4917 }
4918
4919 tmp = btrfs_find_tree_block(root, blockptr,
4920 btrfs_level_size(root, level - 1));
4921
4922 if (tmp && btrfs_buffer_uptodate(tmp, gen, 1) > 0) {
4923 free_extent_buffer(tmp);
4924 break;
4925 }
4926 if (tmp)
4927 free_extent_buffer(tmp);
4928 slot++;
4929 }
4930 find_next_key:
4931 /*
4932 * we didn't find a candidate key in this node, walk forward
4933 * and find another one
4934 */
4935 if (slot >= nritems) {
4936 path->slots[level] = slot;
4937 btrfs_set_path_blocking(path);
4938 sret = btrfs_find_next_key(root, path, min_key, level,
4939 cache_only, min_trans);
4940 if (sret == 0) {
4941 btrfs_release_path(path);
4942 goto again;
4943 } else {
4944 goto out;
4945 }
4946 }
4947 /* save our key for returning back */
4948 btrfs_node_key_to_cpu(cur, &found_key, slot);
4949 path->slots[level] = slot;
4950 if (level == path->lowest_level) {
4951 ret = 0;
4952 unlock_up(path, level, 1, 0, NULL);
4953 goto out;
4954 }
4955 btrfs_set_path_blocking(path);
4956 cur = read_node_slot(root, cur, slot);
4957 BUG_ON(!cur); /* -ENOMEM */
4958
4959 btrfs_tree_read_lock(cur);
4960
4961 path->locks[level - 1] = BTRFS_READ_LOCK;
4962 path->nodes[level - 1] = cur;
4963 unlock_up(path, level, 1, 0, NULL);
4964 btrfs_clear_path_blocking(path, NULL, 0);
4965 }
4966 out:
4967 if (ret == 0)
4968 memcpy(min_key, &found_key, sizeof(found_key));
4969 btrfs_set_path_blocking(path);
4970 return ret;
4971 }
4972
4973 static void tree_move_down(struct btrfs_root *root,
4974 struct btrfs_path *path,
4975 int *level, int root_level)
4976 {
4977 BUG_ON(*level == 0);
4978 path->nodes[*level - 1] = read_node_slot(root, path->nodes[*level],
4979 path->slots[*level]);
4980 path->slots[*level - 1] = 0;
4981 (*level)--;
4982 }
4983
4984 static int tree_move_next_or_upnext(struct btrfs_root *root,
4985 struct btrfs_path *path,
4986 int *level, int root_level)
4987 {
4988 int ret = 0;
4989 int nritems;
4990 nritems = btrfs_header_nritems(path->nodes[*level]);
4991
4992 path->slots[*level]++;
4993
4994 while (path->slots[*level] >= nritems) {
4995 if (*level == root_level)
4996 return -1;
4997
4998 /* move upnext */
4999 path->slots[*level] = 0;
5000 free_extent_buffer(path->nodes[*level]);
5001 path->nodes[*level] = NULL;
5002 (*level)++;
5003 path->slots[*level]++;
5004
5005 nritems = btrfs_header_nritems(path->nodes[*level]);
5006 ret = 1;
5007 }
5008 return ret;
5009 }
5010
5011 /*
5012 * Returns 1 if it had to move up and next. 0 is returned if it moved only next
5013 * or down.
5014 */
5015 static int tree_advance(struct btrfs_root *root,
5016 struct btrfs_path *path,
5017 int *level, int root_level,
5018 int allow_down,
5019 struct btrfs_key *key)
5020 {
5021 int ret;
5022
5023 if (*level == 0 || !allow_down) {
5024 ret = tree_move_next_or_upnext(root, path, level, root_level);
5025 } else {
5026 tree_move_down(root, path, level, root_level);
5027 ret = 0;
5028 }
5029 if (ret >= 0) {
5030 if (*level == 0)
5031 btrfs_item_key_to_cpu(path->nodes[*level], key,
5032 path->slots[*level]);
5033 else
5034 btrfs_node_key_to_cpu(path->nodes[*level], key,
5035 path->slots[*level]);
5036 }
5037 return ret;
5038 }
5039
5040 static int tree_compare_item(struct btrfs_root *left_root,
5041 struct btrfs_path *left_path,
5042 struct btrfs_path *right_path,
5043 char *tmp_buf)
5044 {
5045 int cmp;
5046 int len1, len2;
5047 unsigned long off1, off2;
5048
5049 len1 = btrfs_item_size_nr(left_path->nodes[0], left_path->slots[0]);
5050 len2 = btrfs_item_size_nr(right_path->nodes[0], right_path->slots[0]);
5051 if (len1 != len2)
5052 return 1;
5053
5054 off1 = btrfs_item_ptr_offset(left_path->nodes[0], left_path->slots[0]);
5055 off2 = btrfs_item_ptr_offset(right_path->nodes[0],
5056 right_path->slots[0]);
5057
5058 read_extent_buffer(left_path->nodes[0], tmp_buf, off1, len1);
5059
5060 cmp = memcmp_extent_buffer(right_path->nodes[0], tmp_buf, off2, len1);
5061 if (cmp)
5062 return 1;
5063 return 0;
5064 }
5065
5066 #define ADVANCE 1
5067 #define ADVANCE_ONLY_NEXT -1
5068
5069 /*
5070 * This function compares two trees and calls the provided callback for
5071 * every changed/new/deleted item it finds.
5072 * If shared tree blocks are encountered, whole subtrees are skipped, making
5073 * the compare pretty fast on snapshotted subvolumes.
5074 *
5075 * This currently works on commit roots only. As commit roots are read only,
5076 * we don't do any locking. The commit roots are protected with transactions.
5077 * Transactions are ended and rejoined when a commit is tried in between.
5078 *
5079 * This function checks for modifications done to the trees while comparing.
5080 * If it detects a change, it aborts immediately.
5081 */
5082 int btrfs_compare_trees(struct btrfs_root *left_root,
5083 struct btrfs_root *right_root,
5084 btrfs_changed_cb_t changed_cb, void *ctx)
5085 {
5086 int ret;
5087 int cmp;
5088 struct btrfs_trans_handle *trans = NULL;
5089 struct btrfs_path *left_path = NULL;
5090 struct btrfs_path *right_path = NULL;
5091 struct btrfs_key left_key;
5092 struct btrfs_key right_key;
5093 char *tmp_buf = NULL;
5094 int left_root_level;
5095 int right_root_level;
5096 int left_level;
5097 int right_level;
5098 int left_end_reached;
5099 int right_end_reached;
5100 int advance_left;
5101 int advance_right;
5102 u64 left_blockptr;
5103 u64 right_blockptr;
5104 u64 left_start_ctransid;
5105 u64 right_start_ctransid;
5106 u64 ctransid;
5107
5108 left_path = btrfs_alloc_path();
5109 if (!left_path) {
5110 ret = -ENOMEM;
5111 goto out;
5112 }
5113 right_path = btrfs_alloc_path();
5114 if (!right_path) {
5115 ret = -ENOMEM;
5116 goto out;
5117 }
5118
5119 tmp_buf = kmalloc(left_root->leafsize, GFP_NOFS);
5120 if (!tmp_buf) {
5121 ret = -ENOMEM;
5122 goto out;
5123 }
5124
5125 left_path->search_commit_root = 1;
5126 left_path->skip_locking = 1;
5127 right_path->search_commit_root = 1;
5128 right_path->skip_locking = 1;
5129
5130 spin_lock(&left_root->root_item_lock);
5131 left_start_ctransid = btrfs_root_ctransid(&left_root->root_item);
5132 spin_unlock(&left_root->root_item_lock);
5133
5134 spin_lock(&right_root->root_item_lock);
5135 right_start_ctransid = btrfs_root_ctransid(&right_root->root_item);
5136 spin_unlock(&right_root->root_item_lock);
5137
5138 trans = btrfs_join_transaction(left_root);
5139 if (IS_ERR(trans)) {
5140 ret = PTR_ERR(trans);
5141 trans = NULL;
5142 goto out;
5143 }
5144
5145 /*
5146 * Strategy: Go to the first items of both trees. Then do
5147 *
5148 * If both trees are at level 0
5149 * Compare keys of current items
5150 * If left < right treat left item as new, advance left tree
5151 * and repeat
5152 * If left > right treat right item as deleted, advance right tree
5153 * and repeat
5154 * If left == right do deep compare of items, treat as changed if
5155 * needed, advance both trees and repeat
5156 * If both trees are at the same level but not at level 0
5157 * Compare keys of current nodes/leafs
5158 * If left < right advance left tree and repeat
5159 * If left > right advance right tree and repeat
5160 * If left == right compare blockptrs of the next nodes/leafs
5161 * If they match advance both trees but stay at the same level
5162 * and repeat
5163 * If they don't match advance both trees while allowing to go
5164 * deeper and repeat
5165 * If tree levels are different
5166 * Advance the tree that needs it and repeat
5167 *
5168 * Advancing a tree means:
5169 * If we are at level 0, try to go to the next slot. If that's not
5170 * possible, go one level up and repeat. Stop when we found a level
5171 * where we could go to the next slot. We may at this point be on a
5172 * node or a leaf.
5173 *
5174 * If we are not at level 0 and not on shared tree blocks, go one
5175 * level deeper.
5176 *
5177 * If we are not at level 0 and on shared tree blocks, go one slot to
5178 * the right if possible or go up and right.
5179 */
5180
5181 left_level = btrfs_header_level(left_root->commit_root);
5182 left_root_level = left_level;
5183 left_path->nodes[left_level] = left_root->commit_root;
5184 extent_buffer_get(left_path->nodes[left_level]);
5185
5186 right_level = btrfs_header_level(right_root->commit_root);
5187 right_root_level = right_level;
5188 right_path->nodes[right_level] = right_root->commit_root;
5189 extent_buffer_get(right_path->nodes[right_level]);
5190
5191 if (left_level == 0)
5192 btrfs_item_key_to_cpu(left_path->nodes[left_level],
5193 &left_key, left_path->slots[left_level]);
5194 else
5195 btrfs_node_key_to_cpu(left_path->nodes[left_level],
5196 &left_key, left_path->slots[left_level]);
5197 if (right_level == 0)
5198 btrfs_item_key_to_cpu(right_path->nodes[right_level],
5199 &right_key, right_path->slots[right_level]);
5200 else
5201 btrfs_node_key_to_cpu(right_path->nodes[right_level],
5202 &right_key, right_path->slots[right_level]);
5203
5204 left_end_reached = right_end_reached = 0;
5205 advance_left = advance_right = 0;
5206
5207 while (1) {
5208 /*
5209 * We need to make sure the transaction does not get committed
5210 * while we do anything on commit roots. This means, we need to
5211 * join and leave transactions for every item that we process.
5212 */
5213 if (trans && btrfs_should_end_transaction(trans, left_root)) {
5214 btrfs_release_path(left_path);
5215 btrfs_release_path(right_path);
5216
5217 ret = btrfs_end_transaction(trans, left_root);
5218 trans = NULL;
5219 if (ret < 0)
5220 goto out;
5221 }
5222 /* now rejoin the transaction */
5223 if (!trans) {
5224 trans = btrfs_join_transaction(left_root);
5225 if (IS_ERR(trans)) {
5226 ret = PTR_ERR(trans);
5227 trans = NULL;
5228 goto out;
5229 }
5230
5231 spin_lock(&left_root->root_item_lock);
5232 ctransid = btrfs_root_ctransid(&left_root->root_item);
5233 spin_unlock(&left_root->root_item_lock);
5234 if (ctransid != left_start_ctransid)
5235 left_start_ctransid = 0;
5236
5237 spin_lock(&right_root->root_item_lock);
5238 ctransid = btrfs_root_ctransid(&right_root->root_item);
5239 spin_unlock(&right_root->root_item_lock);
5240 if (ctransid != right_start_ctransid)
5241 right_start_ctransid = 0;
5242
5243 if (!left_start_ctransid || !right_start_ctransid) {
5244 WARN(1, KERN_WARNING
5245 "btrfs: btrfs_compare_tree detected "
5246 "a change in one of the trees while "
5247 "iterating. This is probably a "
5248 "bug.\n");
5249 ret = -EIO;
5250 goto out;
5251 }
5252
5253 /*
5254 * the commit root may have changed, so start again
5255 * where we stopped
5256 */
5257 left_path->lowest_level = left_level;
5258 right_path->lowest_level = right_level;
5259 ret = btrfs_search_slot(NULL, left_root,
5260 &left_key, left_path, 0, 0);
5261 if (ret < 0)
5262 goto out;
5263 ret = btrfs_search_slot(NULL, right_root,
5264 &right_key, right_path, 0, 0);
5265 if (ret < 0)
5266 goto out;
5267 }
5268
5269 if (advance_left && !left_end_reached) {
5270 ret = tree_advance(left_root, left_path, &left_level,
5271 left_root_level,
5272 advance_left != ADVANCE_ONLY_NEXT,
5273 &left_key);
5274 if (ret < 0)
5275 left_end_reached = ADVANCE;
5276 advance_left = 0;
5277 }
5278 if (advance_right && !right_end_reached) {
5279 ret = tree_advance(right_root, right_path, &right_level,
5280 right_root_level,
5281 advance_right != ADVANCE_ONLY_NEXT,
5282 &right_key);
5283 if (ret < 0)
5284 right_end_reached = ADVANCE;
5285 advance_right = 0;
5286 }
5287
5288 if (left_end_reached && right_end_reached) {
5289 ret = 0;
5290 goto out;
5291 } else if (left_end_reached) {
5292 if (right_level == 0) {
5293 ret = changed_cb(left_root, right_root,
5294 left_path, right_path,
5295 &right_key,
5296 BTRFS_COMPARE_TREE_DELETED,
5297 ctx);
5298 if (ret < 0)
5299 goto out;
5300 }
5301 advance_right = ADVANCE;
5302 continue;
5303 } else if (right_end_reached) {
5304 if (left_level == 0) {
5305 ret = changed_cb(left_root, right_root,
5306 left_path, right_path,
5307 &left_key,
5308 BTRFS_COMPARE_TREE_NEW,
5309 ctx);
5310 if (ret < 0)
5311 goto out;
5312 }
5313 advance_left = ADVANCE;
5314 continue;
5315 }
5316
5317 if (left_level == 0 && right_level == 0) {
5318 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5319 if (cmp < 0) {
5320 ret = changed_cb(left_root, right_root,
5321 left_path, right_path,
5322 &left_key,
5323 BTRFS_COMPARE_TREE_NEW,
5324 ctx);
5325 if (ret < 0)
5326 goto out;
5327 advance_left = ADVANCE;
5328 } else if (cmp > 0) {
5329 ret = changed_cb(left_root, right_root,
5330 left_path, right_path,
5331 &right_key,
5332 BTRFS_COMPARE_TREE_DELETED,
5333 ctx);
5334 if (ret < 0)
5335 goto out;
5336 advance_right = ADVANCE;
5337 } else {
5338 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
5339 ret = tree_compare_item(left_root, left_path,
5340 right_path, tmp_buf);
5341 if (ret) {
5342 WARN_ON(!extent_buffer_uptodate(left_path->nodes[0]));
5343 ret = changed_cb(left_root, right_root,
5344 left_path, right_path,
5345 &left_key,
5346 BTRFS_COMPARE_TREE_CHANGED,
5347 ctx);
5348 if (ret < 0)
5349 goto out;
5350 }
5351 advance_left = ADVANCE;
5352 advance_right = ADVANCE;
5353 }
5354 } else if (left_level == right_level) {
5355 cmp = btrfs_comp_cpu_keys(&left_key, &right_key);
5356 if (cmp < 0) {
5357 advance_left = ADVANCE;
5358 } else if (cmp > 0) {
5359 advance_right = ADVANCE;
5360 } else {
5361 left_blockptr = btrfs_node_blockptr(
5362 left_path->nodes[left_level],
5363 left_path->slots[left_level]);
5364 right_blockptr = btrfs_node_blockptr(
5365 right_path->nodes[right_level],
5366 right_path->slots[right_level]);
5367 if (left_blockptr == right_blockptr) {
5368 /*
5369 * As we're on a shared block, don't
5370 * allow to go deeper.
5371 */
5372 advance_left = ADVANCE_ONLY_NEXT;
5373 advance_right = ADVANCE_ONLY_NEXT;
5374 } else {
5375 advance_left = ADVANCE;
5376 advance_right = ADVANCE;
5377 }
5378 }
5379 } else if (left_level < right_level) {
5380 advance_right = ADVANCE;
5381 } else {
5382 advance_left = ADVANCE;
5383 }
5384 }
5385
5386 out:
5387 btrfs_free_path(left_path);
5388 btrfs_free_path(right_path);
5389 kfree(tmp_buf);
5390
5391 if (trans) {
5392 if (!ret)
5393 ret = btrfs_end_transaction(trans, left_root);
5394 else
5395 btrfs_end_transaction(trans, left_root);
5396 }
5397
5398 return ret;
5399 }
5400
5401 /*
5402 * this is similar to btrfs_next_leaf, but does not try to preserve
5403 * and fixup the path. It looks for and returns the next key in the
5404 * tree based on the current path and the cache_only and min_trans
5405 * parameters.
5406 *
5407 * 0 is returned if another key is found, < 0 if there are any errors
5408 * and 1 is returned if there are no higher keys in the tree
5409 *
5410 * path->keep_locks should be set to 1 on the search made before
5411 * calling this function.
5412 */
5413 int btrfs_find_next_key(struct btrfs_root *root, struct btrfs_path *path,
5414 struct btrfs_key *key, int level,
5415 int cache_only, u64 min_trans)
5416 {
5417 int slot;
5418 struct extent_buffer *c;
5419
5420 WARN_ON(!path->keep_locks);
5421 while (level < BTRFS_MAX_LEVEL) {
5422 if (!path->nodes[level])
5423 return 1;
5424
5425 slot = path->slots[level] + 1;
5426 c = path->nodes[level];
5427 next:
5428 if (slot >= btrfs_header_nritems(c)) {
5429 int ret;
5430 int orig_lowest;
5431 struct btrfs_key cur_key;
5432 if (level + 1 >= BTRFS_MAX_LEVEL ||
5433 !path->nodes[level + 1])
5434 return 1;
5435
5436 if (path->locks[level + 1]) {
5437 level++;
5438 continue;
5439 }
5440
5441 slot = btrfs_header_nritems(c) - 1;
5442 if (level == 0)
5443 btrfs_item_key_to_cpu(c, &cur_key, slot);
5444 else
5445 btrfs_node_key_to_cpu(c, &cur_key, slot);
5446
5447 orig_lowest = path->lowest_level;
5448 btrfs_release_path(path);
5449 path->lowest_level = level;
5450 ret = btrfs_search_slot(NULL, root, &cur_key, path,
5451 0, 0);
5452 path->lowest_level = orig_lowest;
5453 if (ret < 0)
5454 return ret;
5455
5456 c = path->nodes[level];
5457 slot = path->slots[level];
5458 if (ret == 0)
5459 slot++;
5460 goto next;
5461 }
5462
5463 if (level == 0)
5464 btrfs_item_key_to_cpu(c, key, slot);
5465 else {
5466 u64 blockptr = btrfs_node_blockptr(c, slot);
5467 u64 gen = btrfs_node_ptr_generation(c, slot);
5468
5469 if (cache_only) {
5470 struct extent_buffer *cur;
5471 cur = btrfs_find_tree_block(root, blockptr,
5472 btrfs_level_size(root, level - 1));
5473 if (!cur ||
5474 btrfs_buffer_uptodate(cur, gen, 1) <= 0) {
5475 slot++;
5476 if (cur)
5477 free_extent_buffer(cur);
5478 goto next;
5479 }
5480 free_extent_buffer(cur);
5481 }
5482 if (gen < min_trans) {
5483 slot++;
5484 goto next;
5485 }
5486 btrfs_node_key_to_cpu(c, key, slot);
5487 }
5488 return 0;
5489 }
5490 return 1;
5491 }
5492
5493 /*
5494 * search the tree again to find a leaf with greater keys
5495 * returns 0 if it found something or 1 if there are no greater leaves.
5496 * returns < 0 on io errors.
5497 */
5498 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
5499 {
5500 return btrfs_next_old_leaf(root, path, 0);
5501 }
5502
5503 /* Release the path up to but not including the given level */
5504 static void btrfs_release_level(struct btrfs_path *path, int level)
5505 {
5506 int i;
5507
5508 for (i = 0; i < level; i++) {
5509 path->slots[i] = 0;
5510 if (!path->nodes[i])
5511 continue;
5512 if (path->locks[i]) {
5513 btrfs_tree_unlock_rw(path->nodes[i], path->locks[i]);
5514 path->locks[i] = 0;
5515 }
5516 free_extent_buffer(path->nodes[i]);
5517 path->nodes[i] = NULL;
5518 }
5519 }
5520
5521 /*
5522 * This function assumes 2 things
5523 *
5524 * 1) You are using path->keep_locks
5525 * 2) You are not inserting items.
5526 *
5527 * If either of these are not true do not use this function. If you need a next
5528 * leaf with either of these not being true then this function can be easily
5529 * adapted to do that, but at the moment these are the limitations.
5530 */
5531 int btrfs_next_leaf_write(struct btrfs_trans_handle *trans,
5532 struct btrfs_root *root, struct btrfs_path *path,
5533 int del)
5534 {
5535 struct extent_buffer *b;
5536 struct btrfs_key key;
5537 u32 nritems;
5538 int level = 1;
5539 int slot;
5540 int ret = 1;
5541 int write_lock_level = BTRFS_MAX_LEVEL;
5542 int ins_len = del ? -1 : 0;
5543
5544 WARN_ON(!(path->keep_locks || path->really_keep_locks));
5545
5546 nritems = btrfs_header_nritems(path->nodes[0]);
5547 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5548
5549 while (path->nodes[level]) {
5550 nritems = btrfs_header_nritems(path->nodes[level]);
5551 if (!(path->locks[level] & BTRFS_WRITE_LOCK)) {
5552 search:
5553 btrfs_release_path(path);
5554 ret = btrfs_search_slot(trans, root, &key, path,
5555 ins_len, 1);
5556 if (ret < 0)
5557 goto out;
5558 level = 1;
5559 continue;
5560 }
5561
5562 if (path->slots[level] >= nritems - 1) {
5563 level++;
5564 continue;
5565 }
5566
5567 btrfs_release_level(path, level);
5568 break;
5569 }
5570
5571 if (!path->nodes[level]) {
5572 ret = 1;
5573 goto out;
5574 }
5575
5576 path->slots[level]++;
5577 b = path->nodes[level];
5578
5579 while (b) {
5580 level = btrfs_header_level(b);
5581
5582 if (!should_cow_block(trans, root, b))
5583 goto cow_done;
5584
5585 btrfs_set_path_blocking(path);
5586 ret = btrfs_cow_block(trans, root, b,
5587 path->nodes[level + 1],
5588 path->slots[level + 1], &b);
5589 if (ret)
5590 goto out;
5591 cow_done:
5592 path->nodes[level] = b;
5593 btrfs_clear_path_blocking(path, NULL, 0);
5594 if (level != 0) {
5595 ret = setup_nodes_for_search(trans, root, path, b,
5596 level, ins_len,
5597 &write_lock_level);
5598 if (ret == -EAGAIN)
5599 goto search;
5600 if (ret)
5601 goto out;
5602
5603 b = path->nodes[level];
5604 slot = path->slots[level];
5605
5606 ret = read_block_for_search(trans, root, path,
5607 &b, level, slot, &key, 0);
5608 if (ret == -EAGAIN)
5609 goto search;
5610 if (ret)
5611 goto out;
5612 level = btrfs_header_level(b);
5613 if (!btrfs_try_tree_write_lock(b)) {
5614 btrfs_set_path_blocking(path);
5615 btrfs_tree_lock(b);
5616 btrfs_clear_path_blocking(path, b,
5617 BTRFS_WRITE_LOCK);
5618 }
5619 path->locks[level] = BTRFS_WRITE_LOCK;
5620 path->nodes[level] = b;
5621 path->slots[level] = 0;
5622 } else {
5623 path->slots[level] = 0;
5624 ret = 0;
5625 break;
5626 }
5627 }
5628
5629 out:
5630 if (ret)
5631 btrfs_release_path(path);
5632
5633 return ret;
5634 }
5635
5636 int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,
5637 u64 time_seq)
5638 {
5639 int slot;
5640 int level;
5641 struct extent_buffer *c;
5642 struct extent_buffer *next;
5643 struct btrfs_key key;
5644 u32 nritems;
5645 int ret;
5646 int old_spinning = path->leave_spinning;
5647 int next_rw_lock = 0;
5648
5649 nritems = btrfs_header_nritems(path->nodes[0]);
5650 if (nritems == 0)
5651 return 1;
5652
5653 btrfs_item_key_to_cpu(path->nodes[0], &key, nritems - 1);
5654 again:
5655 level = 1;
5656 next = NULL;
5657 next_rw_lock = 0;
5658 btrfs_release_path(path);
5659
5660 path->keep_locks = 1;
5661 path->leave_spinning = 1;
5662
5663 if (time_seq)
5664 ret = btrfs_search_old_slot(root, &key, path, time_seq);
5665 else
5666 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
5667 path->keep_locks = 0;
5668
5669 if (ret < 0)
5670 return ret;
5671
5672 nritems = btrfs_header_nritems(path->nodes[0]);
5673 /*
5674 * by releasing the path above we dropped all our locks. A balance
5675 * could have added more items next to the key that used to be
5676 * at the very end of the block. So, check again here and
5677 * advance the path if there are now more items available.
5678 */
5679 if (nritems > 0 && path->slots[0] < nritems - 1) {
5680 if (ret == 0)
5681 path->slots[0]++;
5682 ret = 0;
5683 goto done;
5684 }
5685
5686 while (level < BTRFS_MAX_LEVEL) {
5687 if (!path->nodes[level]) {
5688 ret = 1;
5689 goto done;
5690 }
5691
5692 slot = path->slots[level] + 1;
5693 c = path->nodes[level];
5694 if (slot >= btrfs_header_nritems(c)) {
5695 level++;
5696 if (level == BTRFS_MAX_LEVEL) {
5697 ret = 1;
5698 goto done;
5699 }
5700 continue;
5701 }
5702
5703 if (next) {
5704 btrfs_tree_unlock_rw(next, next_rw_lock);
5705 free_extent_buffer(next);
5706 }
5707
5708 next = c;
5709 next_rw_lock = path->locks[level];
5710 ret = read_block_for_search(NULL, root, path, &next, level,
5711 slot, &key, 0);
5712 if (ret == -EAGAIN)
5713 goto again;
5714
5715 if (ret < 0) {
5716 btrfs_release_path(path);
5717 goto done;
5718 }
5719
5720 if (!path->skip_locking) {
5721 ret = btrfs_try_tree_read_lock(next);
5722 if (!ret && time_seq) {
5723 /*
5724 * If we don't get the lock, we may be racing
5725 * with push_leaf_left, holding that lock while
5726 * itself waiting for the leaf we've currently
5727 * locked. To solve this situation, we give up
5728 * on our lock and cycle.
5729 */
5730 free_extent_buffer(next);
5731 btrfs_release_path(path);
5732 cond_resched();
5733 goto again;
5734 }
5735 if (!ret) {
5736 btrfs_set_path_blocking(path);
5737 btrfs_tree_read_lock(next);
5738 btrfs_clear_path_blocking(path, next,
5739 BTRFS_READ_LOCK);
5740 }
5741 next_rw_lock = BTRFS_READ_LOCK;
5742 }
5743 break;
5744 }
5745 path->slots[level] = slot;
5746 while (1) {
5747 level--;
5748 c = path->nodes[level];
5749 if (path->locks[level])
5750 btrfs_tree_unlock_rw(c, path->locks[level]);
5751
5752 free_extent_buffer(c);
5753 path->nodes[level] = next;
5754 path->slots[level] = 0;
5755 if (!path->skip_locking)
5756 path->locks[level] = next_rw_lock;
5757 if (!level)
5758 break;
5759
5760 ret = read_block_for_search(NULL, root, path, &next, level,
5761 0, &key, 0);
5762 if (ret == -EAGAIN)
5763 goto again;
5764
5765 if (ret < 0) {
5766 btrfs_release_path(path);
5767 goto done;
5768 }
5769
5770 if (!path->skip_locking) {
5771 ret = btrfs_try_tree_read_lock(next);
5772 if (!ret) {
5773 btrfs_set_path_blocking(path);
5774 btrfs_tree_read_lock(next);
5775 btrfs_clear_path_blocking(path, next,
5776 BTRFS_READ_LOCK);
5777 }
5778 next_rw_lock = BTRFS_READ_LOCK;
5779 }
5780 }
5781 ret = 0;
5782 done:
5783 unlock_up(path, 0, 1, 0, NULL);
5784 path->leave_spinning = old_spinning;
5785 if (!old_spinning)
5786 btrfs_set_path_blocking(path);
5787
5788 return ret;
5789 }
5790
5791 /*
5792 * this uses btrfs_prev_leaf to walk backwards in the tree, and keeps
5793 * searching until it gets past min_objectid or finds an item of 'type'
5794 *
5795 * returns 0 if something is found, 1 if nothing was found and < 0 on error
5796 */
5797 int btrfs_previous_item(struct btrfs_root *root,
5798 struct btrfs_path *path, u64 min_objectid,
5799 int type)
5800 {
5801 struct btrfs_key found_key;
5802 struct extent_buffer *leaf;
5803 u32 nritems;
5804 int ret;
5805
5806 while (1) {
5807 if (path->slots[0] == 0) {
5808 btrfs_set_path_blocking(path);
5809 ret = btrfs_prev_leaf(root, path);
5810 if (ret != 0)
5811 return ret;
5812 } else {
5813 path->slots[0]--;
5814 }
5815 leaf = path->nodes[0];
5816 nritems = btrfs_header_nritems(leaf);
5817 if (nritems == 0)
5818 return 1;
5819 if (path->slots[0] == nritems)
5820 path->slots[0]--;
5821
5822 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
5823 if (found_key.objectid < min_objectid)
5824 break;
5825 if (found_key.type == type)
5826 return 0;
5827 if (found_key.objectid == min_objectid &&
5828 found_key.type < type)
5829 break;
5830 }
5831 return 1;
5832 }