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1// SPDX-License-Identifier: GPL-2.0
2
3#include "messages.h"
4#include "tree-mod-log.h"
5#include "disk-io.h"
6#include "fs.h"
7#include "accessors.h"
8#include "tree-checker.h"
9
10struct tree_mod_root {
11 u64 logical;
12 u8 level;
13};
14
15struct tree_mod_elem {
16 struct rb_node node;
17 u64 logical;
18 u64 seq;
19 enum btrfs_mod_log_op op;
20
21 /*
22 * This is used for BTRFS_MOD_LOG_KEY_* and BTRFS_MOD_LOG_MOVE_KEYS
23 * operations.
24 */
25 int slot;
26
27 /* This is used for BTRFS_MOD_LOG_KEY* and BTRFS_MOD_LOG_ROOT_REPLACE. */
28 u64 generation;
29
30 /* Those are used for op == BTRFS_MOD_LOG_KEY_{REPLACE,REMOVE}. */
31 struct btrfs_disk_key key;
32 u64 blockptr;
33
34 /* This is used for op == BTRFS_MOD_LOG_MOVE_KEYS. */
35 struct {
36 int dst_slot;
37 int nr_items;
38 } move;
39
40 /* This is used for op == BTRFS_MOD_LOG_ROOT_REPLACE. */
41 struct tree_mod_root old_root;
42};
43
44/*
45 * Pull a new tree mod seq number for our operation.
46 */
47static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
48{
49 return atomic64_inc_return(&fs_info->tree_mod_seq);
50}
51
52/*
53 * This adds a new blocker to the tree mod log's blocker list if the @elem
54 * passed does not already have a sequence number set. So when a caller expects
55 * to record tree modifications, it should ensure to set elem->seq to zero
56 * before calling btrfs_get_tree_mod_seq.
57 * Returns a fresh, unused tree log modification sequence number, even if no new
58 * blocker was added.
59 */
60u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
61 struct btrfs_seq_list *elem)
62{
63 write_lock(&fs_info->tree_mod_log_lock);
64 if (!elem->seq) {
65 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
66 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
67 set_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags);
68 }
69 write_unlock(&fs_info->tree_mod_log_lock);
70
71 return elem->seq;
72}
73
74void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
75 struct btrfs_seq_list *elem)
76{
77 struct rb_root *tm_root;
78 struct rb_node *node;
79 struct rb_node *next;
80 struct tree_mod_elem *tm;
81 u64 min_seq = BTRFS_SEQ_LAST;
82 u64 seq_putting = elem->seq;
83
84 if (!seq_putting)
85 return;
86
87 write_lock(&fs_info->tree_mod_log_lock);
88 list_del(&elem->list);
89 elem->seq = 0;
90
91 if (list_empty(&fs_info->tree_mod_seq_list)) {
92 clear_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags);
93 } else {
94 struct btrfs_seq_list *first;
95
96 first = list_first_entry(&fs_info->tree_mod_seq_list,
97 struct btrfs_seq_list, list);
98 if (seq_putting > first->seq) {
99 /*
100 * Blocker with lower sequence number exists, we cannot
101 * remove anything from the log.
102 */
103 write_unlock(&fs_info->tree_mod_log_lock);
104 return;
105 }
106 min_seq = first->seq;
107 }
108
109 /*
110 * Anything that's lower than the lowest existing (read: blocked)
111 * sequence number can be removed from the tree.
112 */
113 tm_root = &fs_info->tree_mod_log;
114 for (node = rb_first(tm_root); node; node = next) {
115 next = rb_next(node);
116 tm = rb_entry(node, struct tree_mod_elem, node);
117 if (tm->seq >= min_seq)
118 continue;
119 rb_erase(node, tm_root);
120 kfree(tm);
121 }
122 write_unlock(&fs_info->tree_mod_log_lock);
123}
124
125/*
126 * Key order of the log:
127 * node/leaf start address -> sequence
128 *
129 * The 'start address' is the logical address of the *new* root node for root
130 * replace operations, or the logical address of the affected block for all
131 * other operations.
132 */
133static noinline int tree_mod_log_insert(struct btrfs_fs_info *fs_info,
134 struct tree_mod_elem *tm)
135{
136 struct rb_root *tm_root;
137 struct rb_node **new;
138 struct rb_node *parent = NULL;
139 struct tree_mod_elem *cur;
140
141 lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
142
143 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
144
145 tm_root = &fs_info->tree_mod_log;
146 new = &tm_root->rb_node;
147 while (*new) {
148 cur = rb_entry(*new, struct tree_mod_elem, node);
149 parent = *new;
150 if (cur->logical < tm->logical)
151 new = &((*new)->rb_left);
152 else if (cur->logical > tm->logical)
153 new = &((*new)->rb_right);
154 else if (cur->seq < tm->seq)
155 new = &((*new)->rb_left);
156 else if (cur->seq > tm->seq)
157 new = &((*new)->rb_right);
158 else
159 return -EEXIST;
160 }
161
162 rb_link_node(&tm->node, parent, new);
163 rb_insert_color(&tm->node, tm_root);
164 return 0;
165}
166
167/*
168 * Determines if logging can be omitted. Returns true if it can. Otherwise, it
169 * returns false with the tree_mod_log_lock acquired. The caller must hold
170 * this until all tree mod log insertions are recorded in the rb tree and then
171 * write unlock fs_info::tree_mod_log_lock.
172 */
173static inline bool tree_mod_dont_log(struct btrfs_fs_info *fs_info,
174 struct extent_buffer *eb)
175{
176 if (!test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
177 return true;
178 if (eb && btrfs_header_level(eb) == 0)
179 return true;
180
181 write_lock(&fs_info->tree_mod_log_lock);
182 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
183 write_unlock(&fs_info->tree_mod_log_lock);
184 return true;
185 }
186
187 return false;
188}
189
190/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
191static inline bool tree_mod_need_log(const struct btrfs_fs_info *fs_info,
192 struct extent_buffer *eb)
193{
194 if (!test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
195 return false;
196 if (eb && btrfs_header_level(eb) == 0)
197 return false;
198
199 return true;
200}
201
202static struct tree_mod_elem *alloc_tree_mod_elem(struct extent_buffer *eb,
203 int slot,
204 enum btrfs_mod_log_op op)
205{
206 struct tree_mod_elem *tm;
207
208 tm = kzalloc(sizeof(*tm), GFP_NOFS);
209 if (!tm)
210 return NULL;
211
212 tm->logical = eb->start;
213 if (op != BTRFS_MOD_LOG_KEY_ADD) {
214 btrfs_node_key(eb, &tm->key, slot);
215 tm->blockptr = btrfs_node_blockptr(eb, slot);
216 }
217 tm->op = op;
218 tm->slot = slot;
219 tm->generation = btrfs_node_ptr_generation(eb, slot);
220 RB_CLEAR_NODE(&tm->node);
221
222 return tm;
223}
224
225int btrfs_tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
226 enum btrfs_mod_log_op op)
227{
228 struct tree_mod_elem *tm;
229 int ret;
230
231 if (!tree_mod_need_log(eb->fs_info, eb))
232 return 0;
233
234 tm = alloc_tree_mod_elem(eb, slot, op);
235 if (!tm)
236 return -ENOMEM;
237
238 if (tree_mod_dont_log(eb->fs_info, eb)) {
239 kfree(tm);
240 return 0;
241 }
242
243 ret = tree_mod_log_insert(eb->fs_info, tm);
244 write_unlock(&eb->fs_info->tree_mod_log_lock);
245 if (ret)
246 kfree(tm);
247
248 return ret;
249}
250
251int btrfs_tree_mod_log_insert_move(struct extent_buffer *eb,
252 int dst_slot, int src_slot,
253 int nr_items)
254{
255 struct tree_mod_elem *tm = NULL;
256 struct tree_mod_elem **tm_list = NULL;
257 int ret = 0;
258 int i;
259 bool locked = false;
260
261 if (!tree_mod_need_log(eb->fs_info, eb))
262 return 0;
263
264 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
265 if (!tm_list)
266 return -ENOMEM;
267
268 tm = kzalloc(sizeof(*tm), GFP_NOFS);
269 if (!tm) {
270 ret = -ENOMEM;
271 goto free_tms;
272 }
273
274 tm->logical = eb->start;
275 tm->slot = src_slot;
276 tm->move.dst_slot = dst_slot;
277 tm->move.nr_items = nr_items;
278 tm->op = BTRFS_MOD_LOG_MOVE_KEYS;
279
280 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
281 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
282 BTRFS_MOD_LOG_KEY_REMOVE_WHILE_MOVING);
283 if (!tm_list[i]) {
284 ret = -ENOMEM;
285 goto free_tms;
286 }
287 }
288
289 if (tree_mod_dont_log(eb->fs_info, eb))
290 goto free_tms;
291 locked = true;
292
293 /*
294 * When we override something during the move, we log these removals.
295 * This can only happen when we move towards the beginning of the
296 * buffer, i.e. dst_slot < src_slot.
297 */
298 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
299 ret = tree_mod_log_insert(eb->fs_info, tm_list[i]);
300 if (ret)
301 goto free_tms;
302 }
303
304 ret = tree_mod_log_insert(eb->fs_info, tm);
305 if (ret)
306 goto free_tms;
307 write_unlock(&eb->fs_info->tree_mod_log_lock);
308 kfree(tm_list);
309
310 return 0;
311
312free_tms:
313 for (i = 0; i < nr_items; i++) {
314 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
315 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
316 kfree(tm_list[i]);
317 }
318 if (locked)
319 write_unlock(&eb->fs_info->tree_mod_log_lock);
320 kfree(tm_list);
321 kfree(tm);
322
323 return ret;
324}
325
326static inline int tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
327 struct tree_mod_elem **tm_list,
328 int nritems)
329{
330 int i, j;
331 int ret;
332
333 for (i = nritems - 1; i >= 0; i--) {
334 ret = tree_mod_log_insert(fs_info, tm_list[i]);
335 if (ret) {
336 for (j = nritems - 1; j > i; j--)
337 rb_erase(&tm_list[j]->node,
338 &fs_info->tree_mod_log);
339 return ret;
340 }
341 }
342
343 return 0;
344}
345
346int btrfs_tree_mod_log_insert_root(struct extent_buffer *old_root,
347 struct extent_buffer *new_root,
348 bool log_removal)
349{
350 struct btrfs_fs_info *fs_info = old_root->fs_info;
351 struct tree_mod_elem *tm = NULL;
352 struct tree_mod_elem **tm_list = NULL;
353 int nritems = 0;
354 int ret = 0;
355 int i;
356
357 if (!tree_mod_need_log(fs_info, NULL))
358 return 0;
359
360 if (log_removal && btrfs_header_level(old_root) > 0) {
361 nritems = btrfs_header_nritems(old_root);
362 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
363 GFP_NOFS);
364 if (!tm_list) {
365 ret = -ENOMEM;
366 goto free_tms;
367 }
368 for (i = 0; i < nritems; i++) {
369 tm_list[i] = alloc_tree_mod_elem(old_root, i,
370 BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING);
371 if (!tm_list[i]) {
372 ret = -ENOMEM;
373 goto free_tms;
374 }
375 }
376 }
377
378 tm = kzalloc(sizeof(*tm), GFP_NOFS);
379 if (!tm) {
380 ret = -ENOMEM;
381 goto free_tms;
382 }
383
384 tm->logical = new_root->start;
385 tm->old_root.logical = old_root->start;
386 tm->old_root.level = btrfs_header_level(old_root);
387 tm->generation = btrfs_header_generation(old_root);
388 tm->op = BTRFS_MOD_LOG_ROOT_REPLACE;
389
390 if (tree_mod_dont_log(fs_info, NULL))
391 goto free_tms;
392
393 if (tm_list)
394 ret = tree_mod_log_free_eb(fs_info, tm_list, nritems);
395 if (!ret)
396 ret = tree_mod_log_insert(fs_info, tm);
397
398 write_unlock(&fs_info->tree_mod_log_lock);
399 if (ret)
400 goto free_tms;
401 kfree(tm_list);
402
403 return ret;
404
405free_tms:
406 if (tm_list) {
407 for (i = 0; i < nritems; i++)
408 kfree(tm_list[i]);
409 kfree(tm_list);
410 }
411 kfree(tm);
412
413 return ret;
414}
415
416static struct tree_mod_elem *__tree_mod_log_search(struct btrfs_fs_info *fs_info,
417 u64 start, u64 min_seq,
418 bool smallest)
419{
420 struct rb_root *tm_root;
421 struct rb_node *node;
422 struct tree_mod_elem *cur = NULL;
423 struct tree_mod_elem *found = NULL;
424
425 read_lock(&fs_info->tree_mod_log_lock);
426 tm_root = &fs_info->tree_mod_log;
427 node = tm_root->rb_node;
428 while (node) {
429 cur = rb_entry(node, struct tree_mod_elem, node);
430 if (cur->logical < start) {
431 node = node->rb_left;
432 } else if (cur->logical > start) {
433 node = node->rb_right;
434 } else if (cur->seq < min_seq) {
435 node = node->rb_left;
436 } else if (!smallest) {
437 /* We want the node with the highest seq */
438 if (found)
439 BUG_ON(found->seq > cur->seq);
440 found = cur;
441 node = node->rb_left;
442 } else if (cur->seq > min_seq) {
443 /* We want the node with the smallest seq */
444 if (found)
445 BUG_ON(found->seq < cur->seq);
446 found = cur;
447 node = node->rb_right;
448 } else {
449 found = cur;
450 break;
451 }
452 }
453 read_unlock(&fs_info->tree_mod_log_lock);
454
455 return found;
456}
457
458/*
459 * This returns the element from the log with the smallest time sequence
460 * value that's in the log (the oldest log item). Any element with a time
461 * sequence lower than min_seq will be ignored.
462 */
463static struct tree_mod_elem *tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info,
464 u64 start, u64 min_seq)
465{
466 return __tree_mod_log_search(fs_info, start, min_seq, true);
467}
468
469/*
470 * This returns the element from the log with the largest time sequence
471 * value that's in the log (the most recent log item). Any element with
472 * a time sequence lower than min_seq will be ignored.
473 */
474static struct tree_mod_elem *tree_mod_log_search(struct btrfs_fs_info *fs_info,
475 u64 start, u64 min_seq)
476{
477 return __tree_mod_log_search(fs_info, start, min_seq, false);
478}
479
480int btrfs_tree_mod_log_eb_copy(struct extent_buffer *dst,
481 struct extent_buffer *src,
482 unsigned long dst_offset,
483 unsigned long src_offset,
484 int nr_items)
485{
486 struct btrfs_fs_info *fs_info = dst->fs_info;
487 int ret = 0;
488 struct tree_mod_elem **tm_list = NULL;
489 struct tree_mod_elem **tm_list_add, **tm_list_rem;
490 int i;
491 bool locked = false;
492
493 if (!tree_mod_need_log(fs_info, NULL))
494 return 0;
495
496 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
497 return 0;
498
499 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
500 GFP_NOFS);
501 if (!tm_list)
502 return -ENOMEM;
503
504 tm_list_add = tm_list;
505 tm_list_rem = tm_list + nr_items;
506 for (i = 0; i < nr_items; i++) {
507 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
508 BTRFS_MOD_LOG_KEY_REMOVE);
509 if (!tm_list_rem[i]) {
510 ret = -ENOMEM;
511 goto free_tms;
512 }
513
514 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
515 BTRFS_MOD_LOG_KEY_ADD);
516 if (!tm_list_add[i]) {
517 ret = -ENOMEM;
518 goto free_tms;
519 }
520 }
521
522 if (tree_mod_dont_log(fs_info, NULL))
523 goto free_tms;
524 locked = true;
525
526 for (i = 0; i < nr_items; i++) {
527 ret = tree_mod_log_insert(fs_info, tm_list_rem[i]);
528 if (ret)
529 goto free_tms;
530 ret = tree_mod_log_insert(fs_info, tm_list_add[i]);
531 if (ret)
532 goto free_tms;
533 }
534
535 write_unlock(&fs_info->tree_mod_log_lock);
536 kfree(tm_list);
537
538 return 0;
539
540free_tms:
541 for (i = 0; i < nr_items * 2; i++) {
542 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
543 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
544 kfree(tm_list[i]);
545 }
546 if (locked)
547 write_unlock(&fs_info->tree_mod_log_lock);
548 kfree(tm_list);
549
550 return ret;
551}
552
553int btrfs_tree_mod_log_free_eb(struct extent_buffer *eb)
554{
555 struct tree_mod_elem **tm_list = NULL;
556 int nritems = 0;
557 int i;
558 int ret = 0;
559
560 if (!tree_mod_need_log(eb->fs_info, eb))
561 return 0;
562
563 nritems = btrfs_header_nritems(eb);
564 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
565 if (!tm_list)
566 return -ENOMEM;
567
568 for (i = 0; i < nritems; i++) {
569 tm_list[i] = alloc_tree_mod_elem(eb, i,
570 BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING);
571 if (!tm_list[i]) {
572 ret = -ENOMEM;
573 goto free_tms;
574 }
575 }
576
577 if (tree_mod_dont_log(eb->fs_info, eb))
578 goto free_tms;
579
580 ret = tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
581 write_unlock(&eb->fs_info->tree_mod_log_lock);
582 if (ret)
583 goto free_tms;
584 kfree(tm_list);
585
586 return 0;
587
588free_tms:
589 for (i = 0; i < nritems; i++)
590 kfree(tm_list[i]);
591 kfree(tm_list);
592
593 return ret;
594}
595
596/*
597 * Returns the logical address of the oldest predecessor of the given root.
598 * Entries older than time_seq are ignored.
599 */
600static struct tree_mod_elem *tree_mod_log_oldest_root(struct extent_buffer *eb_root,
601 u64 time_seq)
602{
603 struct tree_mod_elem *tm;
604 struct tree_mod_elem *found = NULL;
605 u64 root_logical = eb_root->start;
606 bool looped = false;
607
608 if (!time_seq)
609 return NULL;
610
611 /*
612 * The very last operation that's logged for a root is the replacement
613 * operation (if it is replaced at all). This has the logical address
614 * of the *new* root, making it the very first operation that's logged
615 * for this root.
616 */
617 while (1) {
618 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
619 time_seq);
620 if (!looped && !tm)
621 return NULL;
622 /*
623 * If there are no tree operation for the oldest root, we simply
624 * return it. This should only happen if that (old) root is at
625 * level 0.
626 */
627 if (!tm)
628 break;
629
630 /*
631 * If there's an operation that's not a root replacement, we
632 * found the oldest version of our root. Normally, we'll find a
633 * BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
634 */
635 if (tm->op != BTRFS_MOD_LOG_ROOT_REPLACE)
636 break;
637
638 found = tm;
639 root_logical = tm->old_root.logical;
640 looped = true;
641 }
642
643 /* If there's no old root to return, return what we found instead */
644 if (!found)
645 found = tm;
646
647 return found;
648}
649
650
651/*
652 * tm is a pointer to the first operation to rewind within eb. Then, all
653 * previous operations will be rewound (until we reach something older than
654 * time_seq).
655 */
656static void tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
657 struct extent_buffer *eb,
658 u64 time_seq,
659 struct tree_mod_elem *first_tm)
660{
661 u32 n;
662 struct rb_node *next;
663 struct tree_mod_elem *tm = first_tm;
664 unsigned long o_dst;
665 unsigned long o_src;
666 unsigned long p_size = sizeof(struct btrfs_key_ptr);
667
668 n = btrfs_header_nritems(eb);
669 read_lock(&fs_info->tree_mod_log_lock);
670 while (tm && tm->seq >= time_seq) {
671 /*
672 * All the operations are recorded with the operator used for
673 * the modification. As we're going backwards, we do the
674 * opposite of each operation here.
675 */
676 switch (tm->op) {
677 case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING:
678 BUG_ON(tm->slot < n);
679 fallthrough;
680 case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_MOVING:
681 case BTRFS_MOD_LOG_KEY_REMOVE:
682 btrfs_set_node_key(eb, &tm->key, tm->slot);
683 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
684 btrfs_set_node_ptr_generation(eb, tm->slot,
685 tm->generation);
686 n++;
687 break;
688 case BTRFS_MOD_LOG_KEY_REPLACE:
689 BUG_ON(tm->slot >= n);
690 btrfs_set_node_key(eb, &tm->key, tm->slot);
691 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
692 btrfs_set_node_ptr_generation(eb, tm->slot,
693 tm->generation);
694 break;
695 case BTRFS_MOD_LOG_KEY_ADD:
696 /* if a move operation is needed it's in the log */
697 n--;
698 break;
699 case BTRFS_MOD_LOG_MOVE_KEYS:
700 o_dst = btrfs_node_key_ptr_offset(eb, tm->slot);
701 o_src = btrfs_node_key_ptr_offset(eb, tm->move.dst_slot);
702 memmove_extent_buffer(eb, o_dst, o_src,
703 tm->move.nr_items * p_size);
704 break;
705 case BTRFS_MOD_LOG_ROOT_REPLACE:
706 /*
707 * This operation is special. For roots, this must be
708 * handled explicitly before rewinding.
709 * For non-roots, this operation may exist if the node
710 * was a root: root A -> child B; then A gets empty and
711 * B is promoted to the new root. In the mod log, we'll
712 * have a root-replace operation for B, a tree block
713 * that is no root. We simply ignore that operation.
714 */
715 break;
716 }
717 next = rb_next(&tm->node);
718 if (!next)
719 break;
720 tm = rb_entry(next, struct tree_mod_elem, node);
721 if (tm->logical != first_tm->logical)
722 break;
723 }
724 read_unlock(&fs_info->tree_mod_log_lock);
725 btrfs_set_header_nritems(eb, n);
726}
727
728/*
729 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
730 * is returned. If rewind operations happen, a fresh buffer is returned. The
731 * returned buffer is always read-locked. If the returned buffer is not the
732 * input buffer, the lock on the input buffer is released and the input buffer
733 * is freed (its refcount is decremented).
734 */
735struct extent_buffer *btrfs_tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
736 struct btrfs_path *path,
737 struct extent_buffer *eb,
738 u64 time_seq)
739{
740 struct extent_buffer *eb_rewin;
741 struct tree_mod_elem *tm;
742
743 if (!time_seq)
744 return eb;
745
746 if (btrfs_header_level(eb) == 0)
747 return eb;
748
749 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
750 if (!tm)
751 return eb;
752
753 if (tm->op == BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
754 BUG_ON(tm->slot != 0);
755 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
756 if (!eb_rewin) {
757 btrfs_tree_read_unlock(eb);
758 free_extent_buffer(eb);
759 return NULL;
760 }
761 btrfs_set_header_bytenr(eb_rewin, eb->start);
762 btrfs_set_header_backref_rev(eb_rewin,
763 btrfs_header_backref_rev(eb));
764 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
765 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
766 } else {
767 eb_rewin = btrfs_clone_extent_buffer(eb);
768 if (!eb_rewin) {
769 btrfs_tree_read_unlock(eb);
770 free_extent_buffer(eb);
771 return NULL;
772 }
773 }
774
775 btrfs_tree_read_unlock(eb);
776 free_extent_buffer(eb);
777
778 btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb_rewin),
779 eb_rewin, btrfs_header_level(eb_rewin));
780 btrfs_tree_read_lock(eb_rewin);
781 tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
782 WARN_ON(btrfs_header_nritems(eb_rewin) >
783 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
784
785 return eb_rewin;
786}
787
788/*
789 * Rewind the state of @root's root node to the given @time_seq value.
790 * If there are no changes, the current root->root_node is returned. If anything
791 * changed in between, there's a fresh buffer allocated on which the rewind
792 * operations are done. In any case, the returned buffer is read locked.
793 * Returns NULL on error (with no locks held).
794 */
795struct extent_buffer *btrfs_get_old_root(struct btrfs_root *root, u64 time_seq)
796{
797 struct btrfs_fs_info *fs_info = root->fs_info;
798 struct tree_mod_elem *tm;
799 struct extent_buffer *eb = NULL;
800 struct extent_buffer *eb_root;
801 u64 eb_root_owner = 0;
802 struct extent_buffer *old;
803 struct tree_mod_root *old_root = NULL;
804 u64 old_generation = 0;
805 u64 logical;
806 int level;
807
808 eb_root = btrfs_read_lock_root_node(root);
809 tm = tree_mod_log_oldest_root(eb_root, time_seq);
810 if (!tm)
811 return eb_root;
812
813 if (tm->op == BTRFS_MOD_LOG_ROOT_REPLACE) {
814 old_root = &tm->old_root;
815 old_generation = tm->generation;
816 logical = old_root->logical;
817 level = old_root->level;
818 } else {
819 logical = eb_root->start;
820 level = btrfs_header_level(eb_root);
821 }
822
823 tm = tree_mod_log_search(fs_info, logical, time_seq);
824 if (old_root && tm && tm->op != BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
825 struct btrfs_tree_parent_check check = { 0 };
826
827 btrfs_tree_read_unlock(eb_root);
828 free_extent_buffer(eb_root);
829
830 check.level = level;
831 check.owner_root = root->root_key.objectid;
832
833 old = read_tree_block(fs_info, logical, &check);
834 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
835 if (!IS_ERR(old))
836 free_extent_buffer(old);
837 btrfs_warn(fs_info,
838 "failed to read tree block %llu from get_old_root",
839 logical);
840 } else {
841 struct tree_mod_elem *tm2;
842
843 btrfs_tree_read_lock(old);
844 eb = btrfs_clone_extent_buffer(old);
845 /*
846 * After the lookup for the most recent tree mod operation
847 * above and before we locked and cloned the extent buffer
848 * 'old', a new tree mod log operation may have been added.
849 * So lookup for a more recent one to make sure the number
850 * of mod log operations we replay is consistent with the
851 * number of items we have in the cloned extent buffer,
852 * otherwise we can hit a BUG_ON when rewinding the extent
853 * buffer.
854 */
855 tm2 = tree_mod_log_search(fs_info, logical, time_seq);
856 btrfs_tree_read_unlock(old);
857 free_extent_buffer(old);
858 ASSERT(tm2);
859 ASSERT(tm2 == tm || tm2->seq > tm->seq);
860 if (!tm2 || tm2->seq < tm->seq) {
861 free_extent_buffer(eb);
862 return NULL;
863 }
864 tm = tm2;
865 }
866 } else if (old_root) {
867 eb_root_owner = btrfs_header_owner(eb_root);
868 btrfs_tree_read_unlock(eb_root);
869 free_extent_buffer(eb_root);
870 eb = alloc_dummy_extent_buffer(fs_info, logical);
871 } else {
872 eb = btrfs_clone_extent_buffer(eb_root);
873 btrfs_tree_read_unlock(eb_root);
874 free_extent_buffer(eb_root);
875 }
876
877 if (!eb)
878 return NULL;
879 if (old_root) {
880 btrfs_set_header_bytenr(eb, eb->start);
881 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
882 btrfs_set_header_owner(eb, eb_root_owner);
883 btrfs_set_header_level(eb, old_root->level);
884 btrfs_set_header_generation(eb, old_generation);
885 }
886 btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb), eb,
887 btrfs_header_level(eb));
888 btrfs_tree_read_lock(eb);
889 if (tm)
890 tree_mod_log_rewind(fs_info, eb, time_seq, tm);
891 else
892 WARN_ON(btrfs_header_level(eb) != 0);
893 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
894
895 return eb;
896}
897
898int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
899{
900 struct tree_mod_elem *tm;
901 int level;
902 struct extent_buffer *eb_root = btrfs_root_node(root);
903
904 tm = tree_mod_log_oldest_root(eb_root, time_seq);
905 if (tm && tm->op == BTRFS_MOD_LOG_ROOT_REPLACE)
906 level = tm->old_root.level;
907 else
908 level = btrfs_header_level(eb_root);
909
910 free_extent_buffer(eb_root);
911
912 return level;
913}
914
915/*
916 * Return the lowest sequence number in the tree modification log.
917 *
918 * Return the sequence number of the oldest tree modification log user, which
919 * corresponds to the lowest sequence number of all existing users. If there are
920 * no users it returns 0.
921 */
922u64 btrfs_tree_mod_log_lowest_seq(struct btrfs_fs_info *fs_info)
923{
924 u64 ret = 0;
925
926 read_lock(&fs_info->tree_mod_log_lock);
927 if (!list_empty(&fs_info->tree_mod_seq_list)) {
928 struct btrfs_seq_list *elem;
929
930 elem = list_first_entry(&fs_info->tree_mod_seq_list,
931 struct btrfs_seq_list, list);
932 ret = elem->seq;
933 }
934 read_unlock(&fs_info->tree_mod_log_lock);
935
936 return ret;
937}
1// SPDX-License-Identifier: GPL-2.0
2
3#include "messages.h"
4#include "tree-mod-log.h"
5#include "disk-io.h"
6#include "fs.h"
7#include "accessors.h"
8#include "tree-checker.h"
9
10struct tree_mod_root {
11 u64 logical;
12 u8 level;
13};
14
15struct tree_mod_elem {
16 struct rb_node node;
17 u64 logical;
18 u64 seq;
19 enum btrfs_mod_log_op op;
20
21 /*
22 * This is used for BTRFS_MOD_LOG_KEY_* and BTRFS_MOD_LOG_MOVE_KEYS
23 * operations.
24 */
25 int slot;
26
27 /* This is used for BTRFS_MOD_LOG_KEY* and BTRFS_MOD_LOG_ROOT_REPLACE. */
28 u64 generation;
29
30 /* Those are used for op == BTRFS_MOD_LOG_KEY_{REPLACE,REMOVE}. */
31 struct btrfs_disk_key key;
32 u64 blockptr;
33
34 /* This is used for op == BTRFS_MOD_LOG_MOVE_KEYS. */
35 struct {
36 int dst_slot;
37 int nr_items;
38 } move;
39
40 /* This is used for op == BTRFS_MOD_LOG_ROOT_REPLACE. */
41 struct tree_mod_root old_root;
42};
43
44/*
45 * Pull a new tree mod seq number for our operation.
46 */
47static inline u64 btrfs_inc_tree_mod_seq(struct btrfs_fs_info *fs_info)
48{
49 return atomic64_inc_return(&fs_info->tree_mod_seq);
50}
51
52/*
53 * This adds a new blocker to the tree mod log's blocker list if the @elem
54 * passed does not already have a sequence number set. So when a caller expects
55 * to record tree modifications, it should ensure to set elem->seq to zero
56 * before calling btrfs_get_tree_mod_seq.
57 * Returns a fresh, unused tree log modification sequence number, even if no new
58 * blocker was added.
59 */
60u64 btrfs_get_tree_mod_seq(struct btrfs_fs_info *fs_info,
61 struct btrfs_seq_list *elem)
62{
63 write_lock(&fs_info->tree_mod_log_lock);
64 if (!elem->seq) {
65 elem->seq = btrfs_inc_tree_mod_seq(fs_info);
66 list_add_tail(&elem->list, &fs_info->tree_mod_seq_list);
67 set_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags);
68 }
69 write_unlock(&fs_info->tree_mod_log_lock);
70
71 return elem->seq;
72}
73
74void btrfs_put_tree_mod_seq(struct btrfs_fs_info *fs_info,
75 struct btrfs_seq_list *elem)
76{
77 struct rb_root *tm_root;
78 struct rb_node *node;
79 struct rb_node *next;
80 struct tree_mod_elem *tm;
81 u64 min_seq = BTRFS_SEQ_LAST;
82 u64 seq_putting = elem->seq;
83
84 if (!seq_putting)
85 return;
86
87 write_lock(&fs_info->tree_mod_log_lock);
88 list_del(&elem->list);
89 elem->seq = 0;
90
91 if (list_empty(&fs_info->tree_mod_seq_list)) {
92 clear_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags);
93 } else {
94 struct btrfs_seq_list *first;
95
96 first = list_first_entry(&fs_info->tree_mod_seq_list,
97 struct btrfs_seq_list, list);
98 if (seq_putting > first->seq) {
99 /*
100 * Blocker with lower sequence number exists, we cannot
101 * remove anything from the log.
102 */
103 write_unlock(&fs_info->tree_mod_log_lock);
104 return;
105 }
106 min_seq = first->seq;
107 }
108
109 /*
110 * Anything that's lower than the lowest existing (read: blocked)
111 * sequence number can be removed from the tree.
112 */
113 tm_root = &fs_info->tree_mod_log;
114 for (node = rb_first(tm_root); node; node = next) {
115 next = rb_next(node);
116 tm = rb_entry(node, struct tree_mod_elem, node);
117 if (tm->seq >= min_seq)
118 continue;
119 rb_erase(node, tm_root);
120 kfree(tm);
121 }
122 write_unlock(&fs_info->tree_mod_log_lock);
123}
124
125/*
126 * Key order of the log:
127 * node/leaf start address -> sequence
128 *
129 * The 'start address' is the logical address of the *new* root node for root
130 * replace operations, or the logical address of the affected block for all
131 * other operations.
132 */
133static noinline int tree_mod_log_insert(struct btrfs_fs_info *fs_info,
134 struct tree_mod_elem *tm)
135{
136 struct rb_root *tm_root;
137 struct rb_node **new;
138 struct rb_node *parent = NULL;
139 struct tree_mod_elem *cur;
140
141 lockdep_assert_held_write(&fs_info->tree_mod_log_lock);
142
143 tm->seq = btrfs_inc_tree_mod_seq(fs_info);
144
145 tm_root = &fs_info->tree_mod_log;
146 new = &tm_root->rb_node;
147 while (*new) {
148 cur = rb_entry(*new, struct tree_mod_elem, node);
149 parent = *new;
150 if (cur->logical < tm->logical)
151 new = &((*new)->rb_left);
152 else if (cur->logical > tm->logical)
153 new = &((*new)->rb_right);
154 else if (cur->seq < tm->seq)
155 new = &((*new)->rb_left);
156 else if (cur->seq > tm->seq)
157 new = &((*new)->rb_right);
158 else
159 return -EEXIST;
160 }
161
162 rb_link_node(&tm->node, parent, new);
163 rb_insert_color(&tm->node, tm_root);
164 return 0;
165}
166
167/*
168 * Determines if logging can be omitted. Returns true if it can. Otherwise, it
169 * returns false with the tree_mod_log_lock acquired. The caller must hold
170 * this until all tree mod log insertions are recorded in the rb tree and then
171 * write unlock fs_info::tree_mod_log_lock.
172 */
173static inline bool tree_mod_dont_log(struct btrfs_fs_info *fs_info,
174 struct extent_buffer *eb)
175{
176 if (!test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
177 return true;
178 if (eb && btrfs_header_level(eb) == 0)
179 return true;
180
181 write_lock(&fs_info->tree_mod_log_lock);
182 if (list_empty(&(fs_info)->tree_mod_seq_list)) {
183 write_unlock(&fs_info->tree_mod_log_lock);
184 return true;
185 }
186
187 return false;
188}
189
190/* Similar to tree_mod_dont_log, but doesn't acquire any locks. */
191static inline bool tree_mod_need_log(const struct btrfs_fs_info *fs_info,
192 struct extent_buffer *eb)
193{
194 if (!test_bit(BTRFS_FS_TREE_MOD_LOG_USERS, &fs_info->flags))
195 return false;
196 if (eb && btrfs_header_level(eb) == 0)
197 return false;
198
199 return true;
200}
201
202static struct tree_mod_elem *alloc_tree_mod_elem(struct extent_buffer *eb,
203 int slot,
204 enum btrfs_mod_log_op op)
205{
206 struct tree_mod_elem *tm;
207
208 tm = kzalloc(sizeof(*tm), GFP_NOFS);
209 if (!tm)
210 return NULL;
211
212 tm->logical = eb->start;
213 if (op != BTRFS_MOD_LOG_KEY_ADD) {
214 btrfs_node_key(eb, &tm->key, slot);
215 tm->blockptr = btrfs_node_blockptr(eb, slot);
216 }
217 tm->op = op;
218 tm->slot = slot;
219 tm->generation = btrfs_node_ptr_generation(eb, slot);
220 RB_CLEAR_NODE(&tm->node);
221
222 return tm;
223}
224
225int btrfs_tree_mod_log_insert_key(struct extent_buffer *eb, int slot,
226 enum btrfs_mod_log_op op)
227{
228 struct tree_mod_elem *tm;
229 int ret = 0;
230
231 if (!tree_mod_need_log(eb->fs_info, eb))
232 return 0;
233
234 tm = alloc_tree_mod_elem(eb, slot, op);
235 if (!tm)
236 ret = -ENOMEM;
237
238 if (tree_mod_dont_log(eb->fs_info, eb)) {
239 kfree(tm);
240 /*
241 * Don't error if we failed to allocate memory because we don't
242 * need to log.
243 */
244 return 0;
245 } else if (ret != 0) {
246 /*
247 * We previously failed to allocate memory and we need to log,
248 * so we have to fail.
249 */
250 goto out_unlock;
251 }
252
253 ret = tree_mod_log_insert(eb->fs_info, tm);
254out_unlock:
255 write_unlock(&eb->fs_info->tree_mod_log_lock);
256 if (ret)
257 kfree(tm);
258
259 return ret;
260}
261
262static struct tree_mod_elem *tree_mod_log_alloc_move(struct extent_buffer *eb,
263 int dst_slot, int src_slot,
264 int nr_items)
265{
266 struct tree_mod_elem *tm;
267
268 tm = kzalloc(sizeof(*tm), GFP_NOFS);
269 if (!tm)
270 return ERR_PTR(-ENOMEM);
271
272 tm->logical = eb->start;
273 tm->slot = src_slot;
274 tm->move.dst_slot = dst_slot;
275 tm->move.nr_items = nr_items;
276 tm->op = BTRFS_MOD_LOG_MOVE_KEYS;
277 RB_CLEAR_NODE(&tm->node);
278
279 return tm;
280}
281
282int btrfs_tree_mod_log_insert_move(struct extent_buffer *eb,
283 int dst_slot, int src_slot,
284 int nr_items)
285{
286 struct tree_mod_elem *tm = NULL;
287 struct tree_mod_elem **tm_list = NULL;
288 int ret = 0;
289 int i;
290 bool locked = false;
291
292 if (!tree_mod_need_log(eb->fs_info, eb))
293 return 0;
294
295 tm_list = kcalloc(nr_items, sizeof(struct tree_mod_elem *), GFP_NOFS);
296 if (!tm_list) {
297 ret = -ENOMEM;
298 goto lock;
299 }
300
301 tm = tree_mod_log_alloc_move(eb, dst_slot, src_slot, nr_items);
302 if (IS_ERR(tm)) {
303 ret = PTR_ERR(tm);
304 tm = NULL;
305 goto lock;
306 }
307
308 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
309 tm_list[i] = alloc_tree_mod_elem(eb, i + dst_slot,
310 BTRFS_MOD_LOG_KEY_REMOVE_WHILE_MOVING);
311 if (!tm_list[i]) {
312 ret = -ENOMEM;
313 goto lock;
314 }
315 }
316
317lock:
318 if (tree_mod_dont_log(eb->fs_info, eb)) {
319 /*
320 * Don't error if we failed to allocate memory because we don't
321 * need to log.
322 */
323 ret = 0;
324 goto free_tms;
325 }
326 locked = true;
327
328 /*
329 * We previously failed to allocate memory and we need to log, so we
330 * have to fail.
331 */
332 if (ret != 0)
333 goto free_tms;
334
335 /*
336 * When we override something during the move, we log these removals.
337 * This can only happen when we move towards the beginning of the
338 * buffer, i.e. dst_slot < src_slot.
339 */
340 for (i = 0; i + dst_slot < src_slot && i < nr_items; i++) {
341 ret = tree_mod_log_insert(eb->fs_info, tm_list[i]);
342 if (ret)
343 goto free_tms;
344 }
345
346 ret = tree_mod_log_insert(eb->fs_info, tm);
347 if (ret)
348 goto free_tms;
349 write_unlock(&eb->fs_info->tree_mod_log_lock);
350 kfree(tm_list);
351
352 return 0;
353
354free_tms:
355 if (tm_list) {
356 for (i = 0; i < nr_items; i++) {
357 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
358 rb_erase(&tm_list[i]->node, &eb->fs_info->tree_mod_log);
359 kfree(tm_list[i]);
360 }
361 }
362 if (locked)
363 write_unlock(&eb->fs_info->tree_mod_log_lock);
364 kfree(tm_list);
365 kfree(tm);
366
367 return ret;
368}
369
370static inline int tree_mod_log_free_eb(struct btrfs_fs_info *fs_info,
371 struct tree_mod_elem **tm_list,
372 int nritems)
373{
374 int i, j;
375 int ret;
376
377 for (i = nritems - 1; i >= 0; i--) {
378 ret = tree_mod_log_insert(fs_info, tm_list[i]);
379 if (ret) {
380 for (j = nritems - 1; j > i; j--)
381 rb_erase(&tm_list[j]->node,
382 &fs_info->tree_mod_log);
383 return ret;
384 }
385 }
386
387 return 0;
388}
389
390int btrfs_tree_mod_log_insert_root(struct extent_buffer *old_root,
391 struct extent_buffer *new_root,
392 bool log_removal)
393{
394 struct btrfs_fs_info *fs_info = old_root->fs_info;
395 struct tree_mod_elem *tm = NULL;
396 struct tree_mod_elem **tm_list = NULL;
397 int nritems = 0;
398 int ret = 0;
399 int i;
400
401 if (!tree_mod_need_log(fs_info, NULL))
402 return 0;
403
404 if (log_removal && btrfs_header_level(old_root) > 0) {
405 nritems = btrfs_header_nritems(old_root);
406 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *),
407 GFP_NOFS);
408 if (!tm_list) {
409 ret = -ENOMEM;
410 goto lock;
411 }
412 for (i = 0; i < nritems; i++) {
413 tm_list[i] = alloc_tree_mod_elem(old_root, i,
414 BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING);
415 if (!tm_list[i]) {
416 ret = -ENOMEM;
417 goto lock;
418 }
419 }
420 }
421
422 tm = kzalloc(sizeof(*tm), GFP_NOFS);
423 if (!tm) {
424 ret = -ENOMEM;
425 goto lock;
426 }
427
428 tm->logical = new_root->start;
429 tm->old_root.logical = old_root->start;
430 tm->old_root.level = btrfs_header_level(old_root);
431 tm->generation = btrfs_header_generation(old_root);
432 tm->op = BTRFS_MOD_LOG_ROOT_REPLACE;
433
434lock:
435 if (tree_mod_dont_log(fs_info, NULL)) {
436 /*
437 * Don't error if we failed to allocate memory because we don't
438 * need to log.
439 */
440 ret = 0;
441 goto free_tms;
442 } else if (ret != 0) {
443 /*
444 * We previously failed to allocate memory and we need to log,
445 * so we have to fail.
446 */
447 goto out_unlock;
448 }
449
450 if (tm_list)
451 ret = tree_mod_log_free_eb(fs_info, tm_list, nritems);
452 if (!ret)
453 ret = tree_mod_log_insert(fs_info, tm);
454
455out_unlock:
456 write_unlock(&fs_info->tree_mod_log_lock);
457 if (ret)
458 goto free_tms;
459 kfree(tm_list);
460
461 return ret;
462
463free_tms:
464 if (tm_list) {
465 for (i = 0; i < nritems; i++)
466 kfree(tm_list[i]);
467 kfree(tm_list);
468 }
469 kfree(tm);
470
471 return ret;
472}
473
474static struct tree_mod_elem *__tree_mod_log_search(struct btrfs_fs_info *fs_info,
475 u64 start, u64 min_seq,
476 bool smallest)
477{
478 struct rb_root *tm_root;
479 struct rb_node *node;
480 struct tree_mod_elem *cur = NULL;
481 struct tree_mod_elem *found = NULL;
482
483 read_lock(&fs_info->tree_mod_log_lock);
484 tm_root = &fs_info->tree_mod_log;
485 node = tm_root->rb_node;
486 while (node) {
487 cur = rb_entry(node, struct tree_mod_elem, node);
488 if (cur->logical < start) {
489 node = node->rb_left;
490 } else if (cur->logical > start) {
491 node = node->rb_right;
492 } else if (cur->seq < min_seq) {
493 node = node->rb_left;
494 } else if (!smallest) {
495 /* We want the node with the highest seq */
496 if (found)
497 BUG_ON(found->seq > cur->seq);
498 found = cur;
499 node = node->rb_left;
500 } else if (cur->seq > min_seq) {
501 /* We want the node with the smallest seq */
502 if (found)
503 BUG_ON(found->seq < cur->seq);
504 found = cur;
505 node = node->rb_right;
506 } else {
507 found = cur;
508 break;
509 }
510 }
511 read_unlock(&fs_info->tree_mod_log_lock);
512
513 return found;
514}
515
516/*
517 * This returns the element from the log with the smallest time sequence
518 * value that's in the log (the oldest log item). Any element with a time
519 * sequence lower than min_seq will be ignored.
520 */
521static struct tree_mod_elem *tree_mod_log_search_oldest(struct btrfs_fs_info *fs_info,
522 u64 start, u64 min_seq)
523{
524 return __tree_mod_log_search(fs_info, start, min_seq, true);
525}
526
527/*
528 * This returns the element from the log with the largest time sequence
529 * value that's in the log (the most recent log item). Any element with
530 * a time sequence lower than min_seq will be ignored.
531 */
532static struct tree_mod_elem *tree_mod_log_search(struct btrfs_fs_info *fs_info,
533 u64 start, u64 min_seq)
534{
535 return __tree_mod_log_search(fs_info, start, min_seq, false);
536}
537
538int btrfs_tree_mod_log_eb_copy(struct extent_buffer *dst,
539 struct extent_buffer *src,
540 unsigned long dst_offset,
541 unsigned long src_offset,
542 int nr_items)
543{
544 struct btrfs_fs_info *fs_info = dst->fs_info;
545 int ret = 0;
546 struct tree_mod_elem **tm_list = NULL;
547 struct tree_mod_elem **tm_list_add = NULL;
548 struct tree_mod_elem **tm_list_rem = NULL;
549 int i;
550 bool locked = false;
551 struct tree_mod_elem *dst_move_tm = NULL;
552 struct tree_mod_elem *src_move_tm = NULL;
553 u32 dst_move_nr_items = btrfs_header_nritems(dst) - dst_offset;
554 u32 src_move_nr_items = btrfs_header_nritems(src) - (src_offset + nr_items);
555
556 if (!tree_mod_need_log(fs_info, NULL))
557 return 0;
558
559 if (btrfs_header_level(dst) == 0 && btrfs_header_level(src) == 0)
560 return 0;
561
562 tm_list = kcalloc(nr_items * 2, sizeof(struct tree_mod_elem *),
563 GFP_NOFS);
564 if (!tm_list) {
565 ret = -ENOMEM;
566 goto lock;
567 }
568
569 if (dst_move_nr_items) {
570 dst_move_tm = tree_mod_log_alloc_move(dst, dst_offset + nr_items,
571 dst_offset, dst_move_nr_items);
572 if (IS_ERR(dst_move_tm)) {
573 ret = PTR_ERR(dst_move_tm);
574 dst_move_tm = NULL;
575 goto lock;
576 }
577 }
578 if (src_move_nr_items) {
579 src_move_tm = tree_mod_log_alloc_move(src, src_offset,
580 src_offset + nr_items,
581 src_move_nr_items);
582 if (IS_ERR(src_move_tm)) {
583 ret = PTR_ERR(src_move_tm);
584 src_move_tm = NULL;
585 goto lock;
586 }
587 }
588
589 tm_list_add = tm_list;
590 tm_list_rem = tm_list + nr_items;
591 for (i = 0; i < nr_items; i++) {
592 tm_list_rem[i] = alloc_tree_mod_elem(src, i + src_offset,
593 BTRFS_MOD_LOG_KEY_REMOVE);
594 if (!tm_list_rem[i]) {
595 ret = -ENOMEM;
596 goto lock;
597 }
598
599 tm_list_add[i] = alloc_tree_mod_elem(dst, i + dst_offset,
600 BTRFS_MOD_LOG_KEY_ADD);
601 if (!tm_list_add[i]) {
602 ret = -ENOMEM;
603 goto lock;
604 }
605 }
606
607lock:
608 if (tree_mod_dont_log(fs_info, NULL)) {
609 /*
610 * Don't error if we failed to allocate memory because we don't
611 * need to log.
612 */
613 ret = 0;
614 goto free_tms;
615 }
616 locked = true;
617
618 /*
619 * We previously failed to allocate memory and we need to log, so we
620 * have to fail.
621 */
622 if (ret != 0)
623 goto free_tms;
624
625 if (dst_move_tm) {
626 ret = tree_mod_log_insert(fs_info, dst_move_tm);
627 if (ret)
628 goto free_tms;
629 }
630 for (i = 0; i < nr_items; i++) {
631 ret = tree_mod_log_insert(fs_info, tm_list_rem[i]);
632 if (ret)
633 goto free_tms;
634 ret = tree_mod_log_insert(fs_info, tm_list_add[i]);
635 if (ret)
636 goto free_tms;
637 }
638 if (src_move_tm) {
639 ret = tree_mod_log_insert(fs_info, src_move_tm);
640 if (ret)
641 goto free_tms;
642 }
643
644 write_unlock(&fs_info->tree_mod_log_lock);
645 kfree(tm_list);
646
647 return 0;
648
649free_tms:
650 if (dst_move_tm && !RB_EMPTY_NODE(&dst_move_tm->node))
651 rb_erase(&dst_move_tm->node, &fs_info->tree_mod_log);
652 kfree(dst_move_tm);
653 if (src_move_tm && !RB_EMPTY_NODE(&src_move_tm->node))
654 rb_erase(&src_move_tm->node, &fs_info->tree_mod_log);
655 kfree(src_move_tm);
656 if (tm_list) {
657 for (i = 0; i < nr_items * 2; i++) {
658 if (tm_list[i] && !RB_EMPTY_NODE(&tm_list[i]->node))
659 rb_erase(&tm_list[i]->node, &fs_info->tree_mod_log);
660 kfree(tm_list[i]);
661 }
662 }
663 if (locked)
664 write_unlock(&fs_info->tree_mod_log_lock);
665 kfree(tm_list);
666
667 return ret;
668}
669
670int btrfs_tree_mod_log_free_eb(struct extent_buffer *eb)
671{
672 struct tree_mod_elem **tm_list = NULL;
673 int nritems = 0;
674 int i;
675 int ret = 0;
676
677 if (!tree_mod_need_log(eb->fs_info, eb))
678 return 0;
679
680 nritems = btrfs_header_nritems(eb);
681 tm_list = kcalloc(nritems, sizeof(struct tree_mod_elem *), GFP_NOFS);
682 if (!tm_list) {
683 ret = -ENOMEM;
684 goto lock;
685 }
686
687 for (i = 0; i < nritems; i++) {
688 tm_list[i] = alloc_tree_mod_elem(eb, i,
689 BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING);
690 if (!tm_list[i]) {
691 ret = -ENOMEM;
692 goto lock;
693 }
694 }
695
696lock:
697 if (tree_mod_dont_log(eb->fs_info, eb)) {
698 /*
699 * Don't error if we failed to allocate memory because we don't
700 * need to log.
701 */
702 ret = 0;
703 goto free_tms;
704 } else if (ret != 0) {
705 /*
706 * We previously failed to allocate memory and we need to log,
707 * so we have to fail.
708 */
709 goto out_unlock;
710 }
711
712 ret = tree_mod_log_free_eb(eb->fs_info, tm_list, nritems);
713out_unlock:
714 write_unlock(&eb->fs_info->tree_mod_log_lock);
715 if (ret)
716 goto free_tms;
717 kfree(tm_list);
718
719 return 0;
720
721free_tms:
722 if (tm_list) {
723 for (i = 0; i < nritems; i++)
724 kfree(tm_list[i]);
725 kfree(tm_list);
726 }
727
728 return ret;
729}
730
731/*
732 * Returns the logical address of the oldest predecessor of the given root.
733 * Entries older than time_seq are ignored.
734 */
735static struct tree_mod_elem *tree_mod_log_oldest_root(struct extent_buffer *eb_root,
736 u64 time_seq)
737{
738 struct tree_mod_elem *tm;
739 struct tree_mod_elem *found = NULL;
740 u64 root_logical = eb_root->start;
741 bool looped = false;
742
743 if (!time_seq)
744 return NULL;
745
746 /*
747 * The very last operation that's logged for a root is the replacement
748 * operation (if it is replaced at all). This has the logical address
749 * of the *new* root, making it the very first operation that's logged
750 * for this root.
751 */
752 while (1) {
753 tm = tree_mod_log_search_oldest(eb_root->fs_info, root_logical,
754 time_seq);
755 if (!looped && !tm)
756 return NULL;
757 /*
758 * If there are no tree operation for the oldest root, we simply
759 * return it. This should only happen if that (old) root is at
760 * level 0.
761 */
762 if (!tm)
763 break;
764
765 /*
766 * If there's an operation that's not a root replacement, we
767 * found the oldest version of our root. Normally, we'll find a
768 * BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING operation here.
769 */
770 if (tm->op != BTRFS_MOD_LOG_ROOT_REPLACE)
771 break;
772
773 found = tm;
774 root_logical = tm->old_root.logical;
775 looped = true;
776 }
777
778 /* If there's no old root to return, return what we found instead */
779 if (!found)
780 found = tm;
781
782 return found;
783}
784
785
786/*
787 * tm is a pointer to the first operation to rewind within eb. Then, all
788 * previous operations will be rewound (until we reach something older than
789 * time_seq).
790 */
791static void tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
792 struct extent_buffer *eb,
793 u64 time_seq,
794 struct tree_mod_elem *first_tm)
795{
796 u32 n;
797 struct rb_node *next;
798 struct tree_mod_elem *tm = first_tm;
799 unsigned long o_dst;
800 unsigned long o_src;
801 unsigned long p_size = sizeof(struct btrfs_key_ptr);
802 /*
803 * max_slot tracks the maximum valid slot of the rewind eb at every
804 * step of the rewind. This is in contrast with 'n' which eventually
805 * matches the number of items, but can be wrong during moves or if
806 * removes overlap on already valid slots (which is probably separately
807 * a bug). We do this to validate the offsets of memmoves for rewinding
808 * moves and detect invalid memmoves.
809 *
810 * Since a rewind eb can start empty, max_slot is a signed integer with
811 * a special meaning for -1, which is that no slot is valid to move out
812 * of. Any other negative value is invalid.
813 */
814 int max_slot;
815 int move_src_end_slot;
816 int move_dst_end_slot;
817
818 n = btrfs_header_nritems(eb);
819 max_slot = n - 1;
820 read_lock(&fs_info->tree_mod_log_lock);
821 while (tm && tm->seq >= time_seq) {
822 ASSERT(max_slot >= -1);
823 /*
824 * All the operations are recorded with the operator used for
825 * the modification. As we're going backwards, we do the
826 * opposite of each operation here.
827 */
828 switch (tm->op) {
829 case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING:
830 BUG_ON(tm->slot < n);
831 fallthrough;
832 case BTRFS_MOD_LOG_KEY_REMOVE_WHILE_MOVING:
833 case BTRFS_MOD_LOG_KEY_REMOVE:
834 btrfs_set_node_key(eb, &tm->key, tm->slot);
835 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
836 btrfs_set_node_ptr_generation(eb, tm->slot,
837 tm->generation);
838 n++;
839 if (tm->slot > max_slot)
840 max_slot = tm->slot;
841 break;
842 case BTRFS_MOD_LOG_KEY_REPLACE:
843 BUG_ON(tm->slot >= n);
844 btrfs_set_node_key(eb, &tm->key, tm->slot);
845 btrfs_set_node_blockptr(eb, tm->slot, tm->blockptr);
846 btrfs_set_node_ptr_generation(eb, tm->slot,
847 tm->generation);
848 break;
849 case BTRFS_MOD_LOG_KEY_ADD:
850 /*
851 * It is possible we could have already removed keys
852 * behind the known max slot, so this will be an
853 * overestimate. In practice, the copy operation
854 * inserts them in increasing order, and overestimating
855 * just means we miss some warnings, so it's OK. It
856 * isn't worth carefully tracking the full array of
857 * valid slots to check against when moving.
858 */
859 if (tm->slot == max_slot)
860 max_slot--;
861 /* if a move operation is needed it's in the log */
862 n--;
863 break;
864 case BTRFS_MOD_LOG_MOVE_KEYS:
865 ASSERT(tm->move.nr_items > 0);
866 move_src_end_slot = tm->move.dst_slot + tm->move.nr_items - 1;
867 move_dst_end_slot = tm->slot + tm->move.nr_items - 1;
868 o_dst = btrfs_node_key_ptr_offset(eb, tm->slot);
869 o_src = btrfs_node_key_ptr_offset(eb, tm->move.dst_slot);
870 if (WARN_ON(move_src_end_slot > max_slot ||
871 tm->move.nr_items <= 0)) {
872 btrfs_warn(fs_info,
873"move from invalid tree mod log slot eb %llu slot %d dst_slot %d nr_items %d seq %llu n %u max_slot %d",
874 eb->start, tm->slot,
875 tm->move.dst_slot, tm->move.nr_items,
876 tm->seq, n, max_slot);
877 }
878 memmove_extent_buffer(eb, o_dst, o_src,
879 tm->move.nr_items * p_size);
880 max_slot = move_dst_end_slot;
881 break;
882 case BTRFS_MOD_LOG_ROOT_REPLACE:
883 /*
884 * This operation is special. For roots, this must be
885 * handled explicitly before rewinding.
886 * For non-roots, this operation may exist if the node
887 * was a root: root A -> child B; then A gets empty and
888 * B is promoted to the new root. In the mod log, we'll
889 * have a root-replace operation for B, a tree block
890 * that is no root. We simply ignore that operation.
891 */
892 break;
893 }
894 next = rb_next(&tm->node);
895 if (!next)
896 break;
897 tm = rb_entry(next, struct tree_mod_elem, node);
898 if (tm->logical != first_tm->logical)
899 break;
900 }
901 read_unlock(&fs_info->tree_mod_log_lock);
902 btrfs_set_header_nritems(eb, n);
903}
904
905/*
906 * Called with eb read locked. If the buffer cannot be rewound, the same buffer
907 * is returned. If rewind operations happen, a fresh buffer is returned. The
908 * returned buffer is always read-locked. If the returned buffer is not the
909 * input buffer, the lock on the input buffer is released and the input buffer
910 * is freed (its refcount is decremented).
911 */
912struct extent_buffer *btrfs_tree_mod_log_rewind(struct btrfs_fs_info *fs_info,
913 struct btrfs_path *path,
914 struct extent_buffer *eb,
915 u64 time_seq)
916{
917 struct extent_buffer *eb_rewin;
918 struct tree_mod_elem *tm;
919
920 if (!time_seq)
921 return eb;
922
923 if (btrfs_header_level(eb) == 0)
924 return eb;
925
926 tm = tree_mod_log_search(fs_info, eb->start, time_seq);
927 if (!tm)
928 return eb;
929
930 if (tm->op == BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
931 BUG_ON(tm->slot != 0);
932 eb_rewin = alloc_dummy_extent_buffer(fs_info, eb->start);
933 if (!eb_rewin) {
934 btrfs_tree_read_unlock(eb);
935 free_extent_buffer(eb);
936 return NULL;
937 }
938 btrfs_set_header_bytenr(eb_rewin, eb->start);
939 btrfs_set_header_backref_rev(eb_rewin,
940 btrfs_header_backref_rev(eb));
941 btrfs_set_header_owner(eb_rewin, btrfs_header_owner(eb));
942 btrfs_set_header_level(eb_rewin, btrfs_header_level(eb));
943 } else {
944 eb_rewin = btrfs_clone_extent_buffer(eb);
945 if (!eb_rewin) {
946 btrfs_tree_read_unlock(eb);
947 free_extent_buffer(eb);
948 return NULL;
949 }
950 }
951
952 btrfs_tree_read_unlock(eb);
953 free_extent_buffer(eb);
954
955 btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb_rewin),
956 eb_rewin, btrfs_header_level(eb_rewin));
957 btrfs_tree_read_lock(eb_rewin);
958 tree_mod_log_rewind(fs_info, eb_rewin, time_seq, tm);
959 WARN_ON(btrfs_header_nritems(eb_rewin) >
960 BTRFS_NODEPTRS_PER_BLOCK(fs_info));
961
962 return eb_rewin;
963}
964
965/*
966 * Rewind the state of @root's root node to the given @time_seq value.
967 * If there are no changes, the current root->root_node is returned. If anything
968 * changed in between, there's a fresh buffer allocated on which the rewind
969 * operations are done. In any case, the returned buffer is read locked.
970 * Returns NULL on error (with no locks held).
971 */
972struct extent_buffer *btrfs_get_old_root(struct btrfs_root *root, u64 time_seq)
973{
974 struct btrfs_fs_info *fs_info = root->fs_info;
975 struct tree_mod_elem *tm;
976 struct extent_buffer *eb = NULL;
977 struct extent_buffer *eb_root;
978 u64 eb_root_owner = 0;
979 struct extent_buffer *old;
980 struct tree_mod_root *old_root = NULL;
981 u64 old_generation = 0;
982 u64 logical;
983 int level;
984
985 eb_root = btrfs_read_lock_root_node(root);
986 tm = tree_mod_log_oldest_root(eb_root, time_seq);
987 if (!tm)
988 return eb_root;
989
990 if (tm->op == BTRFS_MOD_LOG_ROOT_REPLACE) {
991 old_root = &tm->old_root;
992 old_generation = tm->generation;
993 logical = old_root->logical;
994 level = old_root->level;
995 } else {
996 logical = eb_root->start;
997 level = btrfs_header_level(eb_root);
998 }
999
1000 tm = tree_mod_log_search(fs_info, logical, time_seq);
1001 if (old_root && tm && tm->op != BTRFS_MOD_LOG_KEY_REMOVE_WHILE_FREEING) {
1002 struct btrfs_tree_parent_check check = { 0 };
1003
1004 btrfs_tree_read_unlock(eb_root);
1005 free_extent_buffer(eb_root);
1006
1007 check.level = level;
1008 check.owner_root = root->root_key.objectid;
1009
1010 old = read_tree_block(fs_info, logical, &check);
1011 if (WARN_ON(IS_ERR(old) || !extent_buffer_uptodate(old))) {
1012 if (!IS_ERR(old))
1013 free_extent_buffer(old);
1014 btrfs_warn(fs_info,
1015 "failed to read tree block %llu from get_old_root",
1016 logical);
1017 } else {
1018 struct tree_mod_elem *tm2;
1019
1020 btrfs_tree_read_lock(old);
1021 eb = btrfs_clone_extent_buffer(old);
1022 /*
1023 * After the lookup for the most recent tree mod operation
1024 * above and before we locked and cloned the extent buffer
1025 * 'old', a new tree mod log operation may have been added.
1026 * So lookup for a more recent one to make sure the number
1027 * of mod log operations we replay is consistent with the
1028 * number of items we have in the cloned extent buffer,
1029 * otherwise we can hit a BUG_ON when rewinding the extent
1030 * buffer.
1031 */
1032 tm2 = tree_mod_log_search(fs_info, logical, time_seq);
1033 btrfs_tree_read_unlock(old);
1034 free_extent_buffer(old);
1035 ASSERT(tm2);
1036 ASSERT(tm2 == tm || tm2->seq > tm->seq);
1037 if (!tm2 || tm2->seq < tm->seq) {
1038 free_extent_buffer(eb);
1039 return NULL;
1040 }
1041 tm = tm2;
1042 }
1043 } else if (old_root) {
1044 eb_root_owner = btrfs_header_owner(eb_root);
1045 btrfs_tree_read_unlock(eb_root);
1046 free_extent_buffer(eb_root);
1047 eb = alloc_dummy_extent_buffer(fs_info, logical);
1048 } else {
1049 eb = btrfs_clone_extent_buffer(eb_root);
1050 btrfs_tree_read_unlock(eb_root);
1051 free_extent_buffer(eb_root);
1052 }
1053
1054 if (!eb)
1055 return NULL;
1056 if (old_root) {
1057 btrfs_set_header_bytenr(eb, eb->start);
1058 btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV);
1059 btrfs_set_header_owner(eb, eb_root_owner);
1060 btrfs_set_header_level(eb, old_root->level);
1061 btrfs_set_header_generation(eb, old_generation);
1062 }
1063 btrfs_set_buffer_lockdep_class(btrfs_header_owner(eb), eb,
1064 btrfs_header_level(eb));
1065 btrfs_tree_read_lock(eb);
1066 if (tm)
1067 tree_mod_log_rewind(fs_info, eb, time_seq, tm);
1068 else
1069 WARN_ON(btrfs_header_level(eb) != 0);
1070 WARN_ON(btrfs_header_nritems(eb) > BTRFS_NODEPTRS_PER_BLOCK(fs_info));
1071
1072 return eb;
1073}
1074
1075int btrfs_old_root_level(struct btrfs_root *root, u64 time_seq)
1076{
1077 struct tree_mod_elem *tm;
1078 int level;
1079 struct extent_buffer *eb_root = btrfs_root_node(root);
1080
1081 tm = tree_mod_log_oldest_root(eb_root, time_seq);
1082 if (tm && tm->op == BTRFS_MOD_LOG_ROOT_REPLACE)
1083 level = tm->old_root.level;
1084 else
1085 level = btrfs_header_level(eb_root);
1086
1087 free_extent_buffer(eb_root);
1088
1089 return level;
1090}
1091
1092/*
1093 * Return the lowest sequence number in the tree modification log.
1094 *
1095 * Return the sequence number of the oldest tree modification log user, which
1096 * corresponds to the lowest sequence number of all existing users. If there are
1097 * no users it returns 0.
1098 */
1099u64 btrfs_tree_mod_log_lowest_seq(struct btrfs_fs_info *fs_info)
1100{
1101 u64 ret = 0;
1102
1103 read_lock(&fs_info->tree_mod_log_lock);
1104 if (!list_empty(&fs_info->tree_mod_seq_list)) {
1105 struct btrfs_seq_list *elem;
1106
1107 elem = list_first_entry(&fs_info->tree_mod_seq_list,
1108 struct btrfs_seq_list, list);
1109 ret = elem->seq;
1110 }
1111 read_unlock(&fs_info->tree_mod_log_lock);
1112
1113 return ret;
1114}