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