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1// SPDX-License-Identifier: GPL-2.0
2
3#include "bcachefs.h"
4#include "bkey_buf.h"
5#include "btree_key_cache.h"
6#include "btree_update.h"
7#include "buckets.h"
8#include "errcode.h"
9#include "error.h"
10#include "fs.h"
11#include "snapshot.h"
12
13#include <linux/random.h>
14
15/*
16 * Snapshot trees:
17 *
18 * Keys in BTREE_ID_snapshot_trees identify a whole tree of snapshot nodes; they
19 * exist to provide a stable identifier for the whole lifetime of a snapshot
20 * tree.
21 */
22
23void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c,
24 struct bkey_s_c k)
25{
26 struct bkey_s_c_snapshot_tree t = bkey_s_c_to_snapshot_tree(k);
27
28 prt_printf(out, "subvol %u root snapshot %u",
29 le32_to_cpu(t.v->master_subvol),
30 le32_to_cpu(t.v->root_snapshot));
31}
32
33int bch2_snapshot_tree_invalid(struct bch_fs *c, struct bkey_s_c k,
34 enum bkey_invalid_flags flags,
35 struct printbuf *err)
36{
37 int ret = 0;
38
39 bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) ||
40 bkey_lt(k.k->p, POS(0, 1)), c, err,
41 snapshot_tree_pos_bad,
42 "bad pos");
43fsck_err:
44 return ret;
45}
46
47int bch2_snapshot_tree_lookup(struct btree_trans *trans, u32 id,
48 struct bch_snapshot_tree *s)
49{
50 int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_snapshot_trees, POS(0, id),
51 BTREE_ITER_WITH_UPDATES, snapshot_tree, s);
52
53 if (bch2_err_matches(ret, ENOENT))
54 ret = -BCH_ERR_ENOENT_snapshot_tree;
55 return ret;
56}
57
58struct bkey_i_snapshot_tree *
59__bch2_snapshot_tree_create(struct btree_trans *trans)
60{
61 struct btree_iter iter;
62 int ret = bch2_bkey_get_empty_slot(trans, &iter,
63 BTREE_ID_snapshot_trees, POS(0, U32_MAX));
64 struct bkey_i_snapshot_tree *s_t;
65
66 if (ret == -BCH_ERR_ENOSPC_btree_slot)
67 ret = -BCH_ERR_ENOSPC_snapshot_tree;
68 if (ret)
69 return ERR_PTR(ret);
70
71 s_t = bch2_bkey_alloc(trans, &iter, 0, snapshot_tree);
72 ret = PTR_ERR_OR_ZERO(s_t);
73 bch2_trans_iter_exit(trans, &iter);
74 return ret ? ERR_PTR(ret) : s_t;
75}
76
77static int bch2_snapshot_tree_create(struct btree_trans *trans,
78 u32 root_id, u32 subvol_id, u32 *tree_id)
79{
80 struct bkey_i_snapshot_tree *n_tree =
81 __bch2_snapshot_tree_create(trans);
82
83 if (IS_ERR(n_tree))
84 return PTR_ERR(n_tree);
85
86 n_tree->v.master_subvol = cpu_to_le32(subvol_id);
87 n_tree->v.root_snapshot = cpu_to_le32(root_id);
88 *tree_id = n_tree->k.p.offset;
89 return 0;
90}
91
92/* Snapshot nodes: */
93
94static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)
95{
96 struct snapshot_table *t;
97
98 rcu_read_lock();
99 t = rcu_dereference(c->snapshots);
100
101 while (id && id < ancestor)
102 id = __snapshot_t(t, id)->parent;
103 rcu_read_unlock();
104
105 return id == ancestor;
106}
107
108static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)
109{
110 const struct snapshot_t *s = __snapshot_t(t, id);
111
112 if (s->skip[2] <= ancestor)
113 return s->skip[2];
114 if (s->skip[1] <= ancestor)
115 return s->skip[1];
116 if (s->skip[0] <= ancestor)
117 return s->skip[0];
118 return s->parent;
119}
120
121bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
122{
123 struct snapshot_table *t;
124 bool ret;
125
126 EBUG_ON(c->recovery_pass_done <= BCH_RECOVERY_PASS_check_snapshots);
127
128 rcu_read_lock();
129 t = rcu_dereference(c->snapshots);
130
131 while (id && id < ancestor - IS_ANCESTOR_BITMAP)
132 id = get_ancestor_below(t, id, ancestor);
133
134 if (id && id < ancestor) {
135 ret = test_bit(ancestor - id - 1, __snapshot_t(t, id)->is_ancestor);
136
137 EBUG_ON(ret != bch2_snapshot_is_ancestor_early(c, id, ancestor));
138 } else {
139 ret = id == ancestor;
140 }
141
142 rcu_read_unlock();
143
144 return ret;
145}
146
147static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id)
148{
149 size_t idx = U32_MAX - id;
150 size_t new_size;
151 struct snapshot_table *new, *old;
152
153 new_size = max(16UL, roundup_pow_of_two(idx + 1));
154
155 new = kvzalloc(struct_size(new, s, new_size), GFP_KERNEL);
156 if (!new)
157 return NULL;
158
159 old = rcu_dereference_protected(c->snapshots, true);
160 if (old)
161 memcpy(new->s,
162 rcu_dereference_protected(c->snapshots, true)->s,
163 sizeof(new->s[0]) * c->snapshot_table_size);
164
165 rcu_assign_pointer(c->snapshots, new);
166 c->snapshot_table_size = new_size;
167 kvfree_rcu_mightsleep(old);
168
169 return &rcu_dereference_protected(c->snapshots, true)->s[idx];
170}
171
172static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id)
173{
174 size_t idx = U32_MAX - id;
175
176 lockdep_assert_held(&c->snapshot_table_lock);
177
178 if (likely(idx < c->snapshot_table_size))
179 return &rcu_dereference_protected(c->snapshots, true)->s[idx];
180
181 return __snapshot_t_mut(c, id);
182}
183
184void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c,
185 struct bkey_s_c k)
186{
187 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k);
188
189 prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u",
190 BCH_SNAPSHOT_SUBVOL(s.v),
191 BCH_SNAPSHOT_DELETED(s.v),
192 le32_to_cpu(s.v->parent),
193 le32_to_cpu(s.v->children[0]),
194 le32_to_cpu(s.v->children[1]),
195 le32_to_cpu(s.v->subvol),
196 le32_to_cpu(s.v->tree));
197
198 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, depth))
199 prt_printf(out, " depth %u skiplist %u %u %u",
200 le32_to_cpu(s.v->depth),
201 le32_to_cpu(s.v->skip[0]),
202 le32_to_cpu(s.v->skip[1]),
203 le32_to_cpu(s.v->skip[2]));
204}
205
206int bch2_snapshot_invalid(struct bch_fs *c, struct bkey_s_c k,
207 enum bkey_invalid_flags flags,
208 struct printbuf *err)
209{
210 struct bkey_s_c_snapshot s;
211 u32 i, id;
212 int ret = 0;
213
214 bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) ||
215 bkey_lt(k.k->p, POS(0, 1)), c, err,
216 snapshot_pos_bad,
217 "bad pos");
218
219 s = bkey_s_c_to_snapshot(k);
220
221 id = le32_to_cpu(s.v->parent);
222 bkey_fsck_err_on(id && id <= k.k->p.offset, c, err,
223 snapshot_parent_bad,
224 "bad parent node (%u <= %llu)",
225 id, k.k->p.offset);
226
227 bkey_fsck_err_on(le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1]), c, err,
228 snapshot_children_not_normalized,
229 "children not normalized");
230
231 bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1], c, err,
232 snapshot_child_duplicate,
233 "duplicate child nodes");
234
235 for (i = 0; i < 2; i++) {
236 id = le32_to_cpu(s.v->children[i]);
237
238 bkey_fsck_err_on(id >= k.k->p.offset, c, err,
239 snapshot_child_bad,
240 "bad child node (%u >= %llu)",
241 id, k.k->p.offset);
242 }
243
244 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) {
245 bkey_fsck_err_on(le32_to_cpu(s.v->skip[0]) > le32_to_cpu(s.v->skip[1]) ||
246 le32_to_cpu(s.v->skip[1]) > le32_to_cpu(s.v->skip[2]), c, err,
247 snapshot_skiplist_not_normalized,
248 "skiplist not normalized");
249
250 for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) {
251 id = le32_to_cpu(s.v->skip[i]);
252
253 bkey_fsck_err_on(id && id < le32_to_cpu(s.v->parent), c, err,
254 snapshot_skiplist_bad,
255 "bad skiplist node %u", id);
256 }
257 }
258fsck_err:
259 return ret;
260}
261
262static void __set_is_ancestor_bitmap(struct bch_fs *c, u32 id)
263{
264 struct snapshot_t *t = snapshot_t_mut(c, id);
265 u32 parent = id;
266
267 while ((parent = bch2_snapshot_parent_early(c, parent)) &&
268 parent - id - 1 < IS_ANCESTOR_BITMAP)
269 __set_bit(parent - id - 1, t->is_ancestor);
270}
271
272static void set_is_ancestor_bitmap(struct bch_fs *c, u32 id)
273{
274 mutex_lock(&c->snapshot_table_lock);
275 __set_is_ancestor_bitmap(c, id);
276 mutex_unlock(&c->snapshot_table_lock);
277}
278
279static int __bch2_mark_snapshot(struct btree_trans *trans,
280 enum btree_id btree, unsigned level,
281 struct bkey_s_c old, struct bkey_s_c new,
282 unsigned flags)
283{
284 struct bch_fs *c = trans->c;
285 struct snapshot_t *t;
286 u32 id = new.k->p.offset;
287 int ret = 0;
288
289 mutex_lock(&c->snapshot_table_lock);
290
291 t = snapshot_t_mut(c, id);
292 if (!t) {
293 ret = -BCH_ERR_ENOMEM_mark_snapshot;
294 goto err;
295 }
296
297 if (new.k->type == KEY_TYPE_snapshot) {
298 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new);
299
300 t->parent = le32_to_cpu(s.v->parent);
301 t->children[0] = le32_to_cpu(s.v->children[0]);
302 t->children[1] = le32_to_cpu(s.v->children[1]);
303 t->subvol = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0;
304 t->tree = le32_to_cpu(s.v->tree);
305
306 if (bkey_val_bytes(s.k) > offsetof(struct bch_snapshot, depth)) {
307 t->depth = le32_to_cpu(s.v->depth);
308 t->skip[0] = le32_to_cpu(s.v->skip[0]);
309 t->skip[1] = le32_to_cpu(s.v->skip[1]);
310 t->skip[2] = le32_to_cpu(s.v->skip[2]);
311 } else {
312 t->depth = 0;
313 t->skip[0] = 0;
314 t->skip[1] = 0;
315 t->skip[2] = 0;
316 }
317
318 __set_is_ancestor_bitmap(c, id);
319
320 if (BCH_SNAPSHOT_DELETED(s.v)) {
321 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
322 if (c->curr_recovery_pass > BCH_RECOVERY_PASS_delete_dead_snapshots)
323 bch2_delete_dead_snapshots_async(c);
324 }
325 } else {
326 memset(t, 0, sizeof(*t));
327 }
328err:
329 mutex_unlock(&c->snapshot_table_lock);
330 return ret;
331}
332
333int bch2_mark_snapshot(struct btree_trans *trans,
334 enum btree_id btree, unsigned level,
335 struct bkey_s_c old, struct bkey_s new,
336 unsigned flags)
337{
338 return __bch2_mark_snapshot(trans, btree, level, old, new.s_c, flags);
339}
340
341int bch2_snapshot_lookup(struct btree_trans *trans, u32 id,
342 struct bch_snapshot *s)
343{
344 return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id),
345 BTREE_ITER_WITH_UPDATES, snapshot, s);
346}
347
348static int bch2_snapshot_live(struct btree_trans *trans, u32 id)
349{
350 struct bch_snapshot v;
351 int ret;
352
353 if (!id)
354 return 0;
355
356 ret = bch2_snapshot_lookup(trans, id, &v);
357 if (bch2_err_matches(ret, ENOENT))
358 bch_err(trans->c, "snapshot node %u not found", id);
359 if (ret)
360 return ret;
361
362 return !BCH_SNAPSHOT_DELETED(&v);
363}
364
365/*
366 * If @k is a snapshot with just one live child, it's part of a linear chain,
367 * which we consider to be an equivalence class: and then after snapshot
368 * deletion cleanup, there should only be a single key at a given position in
369 * this equivalence class.
370 *
371 * This sets the equivalence class of @k to be the child's equivalence class, if
372 * it's part of such a linear chain: this correctly sets equivalence classes on
373 * startup if we run leaf to root (i.e. in natural key order).
374 */
375static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
376{
377 struct bch_fs *c = trans->c;
378 unsigned i, nr_live = 0, live_idx = 0;
379 struct bkey_s_c_snapshot snap;
380 u32 id = k.k->p.offset, child[2];
381
382 if (k.k->type != KEY_TYPE_snapshot)
383 return 0;
384
385 snap = bkey_s_c_to_snapshot(k);
386
387 child[0] = le32_to_cpu(snap.v->children[0]);
388 child[1] = le32_to_cpu(snap.v->children[1]);
389
390 for (i = 0; i < 2; i++) {
391 int ret = bch2_snapshot_live(trans, child[i]);
392
393 if (ret < 0)
394 return ret;
395
396 if (ret)
397 live_idx = i;
398 nr_live += ret;
399 }
400
401 mutex_lock(&c->snapshot_table_lock);
402
403 snapshot_t_mut(c, id)->equiv = nr_live == 1
404 ? snapshot_t_mut(c, child[live_idx])->equiv
405 : id;
406
407 mutex_unlock(&c->snapshot_table_lock);
408
409 return 0;
410}
411
412/* fsck: */
413
414static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child)
415{
416 return snapshot_t(c, id)->children[child];
417}
418
419static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id)
420{
421 return bch2_snapshot_child(c, id, 0);
422}
423
424static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id)
425{
426 return bch2_snapshot_child(c, id, 1);
427}
428
429static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id)
430{
431 u32 n, parent;
432
433 n = bch2_snapshot_left_child(c, id);
434 if (n)
435 return n;
436
437 while ((parent = bch2_snapshot_parent(c, id))) {
438 n = bch2_snapshot_right_child(c, parent);
439 if (n && n != id)
440 return n;
441 id = parent;
442 }
443
444 return 0;
445}
446
447static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root)
448{
449 u32 id = snapshot_root;
450 u32 subvol = 0, s;
451
452 while (id) {
453 s = snapshot_t(c, id)->subvol;
454
455 if (s && (!subvol || s < subvol))
456 subvol = s;
457
458 id = bch2_snapshot_tree_next(c, id);
459 }
460
461 return subvol;
462}
463
464static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans,
465 u32 snapshot_root, u32 *subvol_id)
466{
467 struct bch_fs *c = trans->c;
468 struct btree_iter iter;
469 struct bkey_s_c k;
470 bool found = false;
471 int ret;
472
473 for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,
474 0, k, ret) {
475 if (k.k->type != KEY_TYPE_subvolume)
476 continue;
477
478 struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
479 if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root))
480 continue;
481 if (!BCH_SUBVOLUME_SNAP(s.v)) {
482 *subvol_id = s.k->p.offset;
483 found = true;
484 break;
485 }
486 }
487
488 bch2_trans_iter_exit(trans, &iter);
489
490 if (!ret && !found) {
491 struct bkey_i_subvolume *u;
492
493 *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root);
494
495 u = bch2_bkey_get_mut_typed(trans, &iter,
496 BTREE_ID_subvolumes, POS(0, *subvol_id),
497 0, subvolume);
498 ret = PTR_ERR_OR_ZERO(u);
499 if (ret)
500 return ret;
501
502 SET_BCH_SUBVOLUME_SNAP(&u->v, false);
503 }
504
505 return ret;
506}
507
508static int check_snapshot_tree(struct btree_trans *trans,
509 struct btree_iter *iter,
510 struct bkey_s_c k)
511{
512 struct bch_fs *c = trans->c;
513 struct bkey_s_c_snapshot_tree st;
514 struct bch_snapshot s;
515 struct bch_subvolume subvol;
516 struct printbuf buf = PRINTBUF;
517 u32 root_id;
518 int ret;
519
520 if (k.k->type != KEY_TYPE_snapshot_tree)
521 return 0;
522
523 st = bkey_s_c_to_snapshot_tree(k);
524 root_id = le32_to_cpu(st.v->root_snapshot);
525
526 ret = bch2_snapshot_lookup(trans, root_id, &s);
527 if (ret && !bch2_err_matches(ret, ENOENT))
528 goto err;
529
530 if (fsck_err_on(ret ||
531 root_id != bch2_snapshot_root(c, root_id) ||
532 st.k->p.offset != le32_to_cpu(s.tree),
533 c, snapshot_tree_to_missing_snapshot,
534 "snapshot tree points to missing/incorrect snapshot:\n %s",
535 (bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
536 ret = bch2_btree_delete_at(trans, iter, 0);
537 goto err;
538 }
539
540 ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol),
541 false, 0, &subvol);
542 if (ret && !bch2_err_matches(ret, ENOENT))
543 goto err;
544
545 if (fsck_err_on(ret,
546 c, snapshot_tree_to_missing_subvol,
547 "snapshot tree points to missing subvolume:\n %s",
548 (printbuf_reset(&buf),
549 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
550 fsck_err_on(!bch2_snapshot_is_ancestor_early(c,
551 le32_to_cpu(subvol.snapshot),
552 root_id),
553 c, snapshot_tree_to_wrong_subvol,
554 "snapshot tree points to subvolume that does not point to snapshot in this tree:\n %s",
555 (printbuf_reset(&buf),
556 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
557 fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol),
558 c, snapshot_tree_to_snapshot_subvol,
559 "snapshot tree points to snapshot subvolume:\n %s",
560 (printbuf_reset(&buf),
561 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
562 struct bkey_i_snapshot_tree *u;
563 u32 subvol_id;
564
565 ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id);
566 if (ret)
567 goto err;
568
569 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree);
570 ret = PTR_ERR_OR_ZERO(u);
571 if (ret)
572 goto err;
573
574 u->v.master_subvol = cpu_to_le32(subvol_id);
575 st = snapshot_tree_i_to_s_c(u);
576 }
577err:
578fsck_err:
579 printbuf_exit(&buf);
580 return ret;
581}
582
583/*
584 * For each snapshot_tree, make sure it points to the root of a snapshot tree
585 * and that snapshot entry points back to it, or delete it.
586 *
587 * And, make sure it points to a subvolume within that snapshot tree, or correct
588 * it to point to the oldest subvolume within that snapshot tree.
589 */
590int bch2_check_snapshot_trees(struct bch_fs *c)
591{
592 int ret = bch2_trans_run(c,
593 for_each_btree_key_commit(trans, iter,
594 BTREE_ID_snapshot_trees, POS_MIN,
595 BTREE_ITER_PREFETCH, k,
596 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
597 check_snapshot_tree(trans, &iter, k)));
598 bch_err_fn(c, ret);
599 return ret;
600}
601
602/*
603 * Look up snapshot tree for @tree_id and find root,
604 * make sure @snap_id is a descendent:
605 */
606static int snapshot_tree_ptr_good(struct btree_trans *trans,
607 u32 snap_id, u32 tree_id)
608{
609 struct bch_snapshot_tree s_t;
610 int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
611
612 if (bch2_err_matches(ret, ENOENT))
613 return 0;
614 if (ret)
615 return ret;
616
617 return bch2_snapshot_is_ancestor_early(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot));
618}
619
620u32 bch2_snapshot_skiplist_get(struct bch_fs *c, u32 id)
621{
622 const struct snapshot_t *s;
623
624 if (!id)
625 return 0;
626
627 rcu_read_lock();
628 s = snapshot_t(c, id);
629 if (s->parent)
630 id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth));
631 rcu_read_unlock();
632
633 return id;
634}
635
636static int snapshot_skiplist_good(struct btree_trans *trans, u32 id, struct bch_snapshot s)
637{
638 unsigned i;
639
640 for (i = 0; i < 3; i++)
641 if (!s.parent) {
642 if (s.skip[i])
643 return false;
644 } else {
645 if (!bch2_snapshot_is_ancestor_early(trans->c, id, le32_to_cpu(s.skip[i])))
646 return false;
647 }
648
649 return true;
650}
651
652/*
653 * snapshot_tree pointer was incorrect: look up root snapshot node, make sure
654 * its snapshot_tree pointer is correct (allocate new one if necessary), then
655 * update this node's pointer to root node's pointer:
656 */
657static int snapshot_tree_ptr_repair(struct btree_trans *trans,
658 struct btree_iter *iter,
659 struct bkey_s_c k,
660 struct bch_snapshot *s)
661{
662 struct bch_fs *c = trans->c;
663 struct btree_iter root_iter;
664 struct bch_snapshot_tree s_t;
665 struct bkey_s_c_snapshot root;
666 struct bkey_i_snapshot *u;
667 u32 root_id = bch2_snapshot_root(c, k.k->p.offset), tree_id;
668 int ret;
669
670 root = bch2_bkey_get_iter_typed(trans, &root_iter,
671 BTREE_ID_snapshots, POS(0, root_id),
672 BTREE_ITER_WITH_UPDATES, snapshot);
673 ret = bkey_err(root);
674 if (ret)
675 goto err;
676
677 tree_id = le32_to_cpu(root.v->tree);
678
679 ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
680 if (ret && !bch2_err_matches(ret, ENOENT))
681 return ret;
682
683 if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) {
684 u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot);
685 ret = PTR_ERR_OR_ZERO(u) ?:
686 bch2_snapshot_tree_create(trans, root_id,
687 bch2_snapshot_tree_oldest_subvol(c, root_id),
688 &tree_id);
689 if (ret)
690 goto err;
691
692 u->v.tree = cpu_to_le32(tree_id);
693 if (k.k->p.offset == root_id)
694 *s = u->v;
695 }
696
697 if (k.k->p.offset != root_id) {
698 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
699 ret = PTR_ERR_OR_ZERO(u);
700 if (ret)
701 goto err;
702
703 u->v.tree = cpu_to_le32(tree_id);
704 *s = u->v;
705 }
706err:
707 bch2_trans_iter_exit(trans, &root_iter);
708 return ret;
709}
710
711static int check_snapshot(struct btree_trans *trans,
712 struct btree_iter *iter,
713 struct bkey_s_c k)
714{
715 struct bch_fs *c = trans->c;
716 struct bch_snapshot s;
717 struct bch_subvolume subvol;
718 struct bch_snapshot v;
719 struct bkey_i_snapshot *u;
720 u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset);
721 u32 real_depth;
722 struct printbuf buf = PRINTBUF;
723 bool should_have_subvol;
724 u32 i, id;
725 int ret = 0;
726
727 if (k.k->type != KEY_TYPE_snapshot)
728 return 0;
729
730 memset(&s, 0, sizeof(s));
731 memcpy(&s, k.v, min(sizeof(s), bkey_val_bytes(k.k)));
732
733 id = le32_to_cpu(s.parent);
734 if (id) {
735 ret = bch2_snapshot_lookup(trans, id, &v);
736 if (bch2_err_matches(ret, ENOENT))
737 bch_err(c, "snapshot with nonexistent parent:\n %s",
738 (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
739 if (ret)
740 goto err;
741
742 if (le32_to_cpu(v.children[0]) != k.k->p.offset &&
743 le32_to_cpu(v.children[1]) != k.k->p.offset) {
744 bch_err(c, "snapshot parent %u missing pointer to child %llu",
745 id, k.k->p.offset);
746 ret = -EINVAL;
747 goto err;
748 }
749 }
750
751 for (i = 0; i < 2 && s.children[i]; i++) {
752 id = le32_to_cpu(s.children[i]);
753
754 ret = bch2_snapshot_lookup(trans, id, &v);
755 if (bch2_err_matches(ret, ENOENT))
756 bch_err(c, "snapshot node %llu has nonexistent child %u",
757 k.k->p.offset, id);
758 if (ret)
759 goto err;
760
761 if (le32_to_cpu(v.parent) != k.k->p.offset) {
762 bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)",
763 id, le32_to_cpu(v.parent), k.k->p.offset);
764 ret = -EINVAL;
765 goto err;
766 }
767 }
768
769 should_have_subvol = BCH_SNAPSHOT_SUBVOL(&s) &&
770 !BCH_SNAPSHOT_DELETED(&s);
771
772 if (should_have_subvol) {
773 id = le32_to_cpu(s.subvol);
774 ret = bch2_subvolume_get(trans, id, 0, false, &subvol);
775 if (bch2_err_matches(ret, ENOENT))
776 bch_err(c, "snapshot points to nonexistent subvolume:\n %s",
777 (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
778 if (ret)
779 goto err;
780
781 if (BCH_SNAPSHOT_SUBVOL(&s) != (le32_to_cpu(subvol.snapshot) == k.k->p.offset)) {
782 bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",
783 k.k->p.offset);
784 ret = -EINVAL;
785 goto err;
786 }
787 } else {
788 if (fsck_err_on(s.subvol,
789 c, snapshot_should_not_have_subvol,
790 "snapshot should not point to subvol:\n %s",
791 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
792 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
793 ret = PTR_ERR_OR_ZERO(u);
794 if (ret)
795 goto err;
796
797 u->v.subvol = 0;
798 s = u->v;
799 }
800 }
801
802 ret = snapshot_tree_ptr_good(trans, k.k->p.offset, le32_to_cpu(s.tree));
803 if (ret < 0)
804 goto err;
805
806 if (fsck_err_on(!ret, c, snapshot_to_bad_snapshot_tree,
807 "snapshot points to missing/incorrect tree:\n %s",
808 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
809 ret = snapshot_tree_ptr_repair(trans, iter, k, &s);
810 if (ret)
811 goto err;
812 }
813 ret = 0;
814
815 real_depth = bch2_snapshot_depth(c, parent_id);
816
817 if (fsck_err_on(le32_to_cpu(s.depth) != real_depth,
818 c, snapshot_bad_depth,
819 "snapshot with incorrect depth field, should be %u:\n %s",
820 real_depth, (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
821 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
822 ret = PTR_ERR_OR_ZERO(u);
823 if (ret)
824 goto err;
825
826 u->v.depth = cpu_to_le32(real_depth);
827 s = u->v;
828 }
829
830 ret = snapshot_skiplist_good(trans, k.k->p.offset, s);
831 if (ret < 0)
832 goto err;
833
834 if (fsck_err_on(!ret, c, snapshot_bad_skiplist,
835 "snapshot with bad skiplist field:\n %s",
836 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
837 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
838 ret = PTR_ERR_OR_ZERO(u);
839 if (ret)
840 goto err;
841
842 for (i = 0; i < ARRAY_SIZE(u->v.skip); i++)
843 u->v.skip[i] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent_id));
844
845 bubble_sort(u->v.skip, ARRAY_SIZE(u->v.skip), cmp_le32);
846 s = u->v;
847 }
848 ret = 0;
849err:
850fsck_err:
851 printbuf_exit(&buf);
852 return ret;
853}
854
855int bch2_check_snapshots(struct bch_fs *c)
856{
857 /*
858 * We iterate backwards as checking/fixing the depth field requires that
859 * the parent's depth already be correct:
860 */
861 int ret = bch2_trans_run(c,
862 for_each_btree_key_reverse_commit(trans, iter,
863 BTREE_ID_snapshots, POS_MAX,
864 BTREE_ITER_PREFETCH, k,
865 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
866 check_snapshot(trans, &iter, k)));
867 bch_err_fn(c, ret);
868 return ret;
869}
870
871/*
872 * Mark a snapshot as deleted, for future cleanup:
873 */
874int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
875{
876 struct btree_iter iter;
877 struct bkey_i_snapshot *s;
878 int ret = 0;
879
880 s = bch2_bkey_get_mut_typed(trans, &iter,
881 BTREE_ID_snapshots, POS(0, id),
882 0, snapshot);
883 ret = PTR_ERR_OR_ZERO(s);
884 if (unlikely(ret)) {
885 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT),
886 trans->c, "missing snapshot %u", id);
887 return ret;
888 }
889
890 /* already deleted? */
891 if (BCH_SNAPSHOT_DELETED(&s->v))
892 goto err;
893
894 SET_BCH_SNAPSHOT_DELETED(&s->v, true);
895 SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);
896 s->v.subvol = 0;
897err:
898 bch2_trans_iter_exit(trans, &iter);
899 return ret;
900}
901
902static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s)
903{
904 if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1]))
905 swap(s->children[0], s->children[1]);
906}
907
908static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id)
909{
910 struct bch_fs *c = trans->c;
911 struct btree_iter iter, p_iter = (struct btree_iter) { NULL };
912 struct btree_iter c_iter = (struct btree_iter) { NULL };
913 struct btree_iter tree_iter = (struct btree_iter) { NULL };
914 struct bkey_s_c_snapshot s;
915 u32 parent_id, child_id;
916 unsigned i;
917 int ret = 0;
918
919 s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id),
920 BTREE_ITER_INTENT, snapshot);
921 ret = bkey_err(s);
922 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
923 "missing snapshot %u", id);
924
925 if (ret)
926 goto err;
927
928 BUG_ON(s.v->children[1]);
929
930 parent_id = le32_to_cpu(s.v->parent);
931 child_id = le32_to_cpu(s.v->children[0]);
932
933 if (parent_id) {
934 struct bkey_i_snapshot *parent;
935
936 parent = bch2_bkey_get_mut_typed(trans, &p_iter,
937 BTREE_ID_snapshots, POS(0, parent_id),
938 0, snapshot);
939 ret = PTR_ERR_OR_ZERO(parent);
940 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
941 "missing snapshot %u", parent_id);
942 if (unlikely(ret))
943 goto err;
944
945 /* find entry in parent->children for node being deleted */
946 for (i = 0; i < 2; i++)
947 if (le32_to_cpu(parent->v.children[i]) == id)
948 break;
949
950 if (bch2_fs_inconsistent_on(i == 2, c,
951 "snapshot %u missing child pointer to %u",
952 parent_id, id))
953 goto err;
954
955 parent->v.children[i] = cpu_to_le32(child_id);
956
957 normalize_snapshot_child_pointers(&parent->v);
958 }
959
960 if (child_id) {
961 struct bkey_i_snapshot *child;
962
963 child = bch2_bkey_get_mut_typed(trans, &c_iter,
964 BTREE_ID_snapshots, POS(0, child_id),
965 0, snapshot);
966 ret = PTR_ERR_OR_ZERO(child);
967 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
968 "missing snapshot %u", child_id);
969 if (unlikely(ret))
970 goto err;
971
972 child->v.parent = cpu_to_le32(parent_id);
973
974 if (!child->v.parent) {
975 child->v.skip[0] = 0;
976 child->v.skip[1] = 0;
977 child->v.skip[2] = 0;
978 }
979 }
980
981 if (!parent_id) {
982 /*
983 * We're deleting the root of a snapshot tree: update the
984 * snapshot_tree entry to point to the new root, or delete it if
985 * this is the last snapshot ID in this tree:
986 */
987 struct bkey_i_snapshot_tree *s_t;
988
989 BUG_ON(s.v->children[1]);
990
991 s_t = bch2_bkey_get_mut_typed(trans, &tree_iter,
992 BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)),
993 0, snapshot_tree);
994 ret = PTR_ERR_OR_ZERO(s_t);
995 if (ret)
996 goto err;
997
998 if (s.v->children[0]) {
999 s_t->v.root_snapshot = s.v->children[0];
1000 } else {
1001 s_t->k.type = KEY_TYPE_deleted;
1002 set_bkey_val_u64s(&s_t->k, 0);
1003 }
1004 }
1005
1006 ret = bch2_btree_delete_at(trans, &iter, 0);
1007err:
1008 bch2_trans_iter_exit(trans, &tree_iter);
1009 bch2_trans_iter_exit(trans, &p_iter);
1010 bch2_trans_iter_exit(trans, &c_iter);
1011 bch2_trans_iter_exit(trans, &iter);
1012 return ret;
1013}
1014
1015static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,
1016 u32 *new_snapids,
1017 u32 *snapshot_subvols,
1018 unsigned nr_snapids)
1019{
1020 struct bch_fs *c = trans->c;
1021 struct btree_iter iter;
1022 struct bkey_i_snapshot *n;
1023 struct bkey_s_c k;
1024 unsigned i, j;
1025 u32 depth = bch2_snapshot_depth(c, parent);
1026 int ret;
1027
1028 bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,
1029 POS_MIN, BTREE_ITER_INTENT);
1030 k = bch2_btree_iter_peek(&iter);
1031 ret = bkey_err(k);
1032 if (ret)
1033 goto err;
1034
1035 for (i = 0; i < nr_snapids; i++) {
1036 k = bch2_btree_iter_prev_slot(&iter);
1037 ret = bkey_err(k);
1038 if (ret)
1039 goto err;
1040
1041 if (!k.k || !k.k->p.offset) {
1042 ret = -BCH_ERR_ENOSPC_snapshot_create;
1043 goto err;
1044 }
1045
1046 n = bch2_bkey_alloc(trans, &iter, 0, snapshot);
1047 ret = PTR_ERR_OR_ZERO(n);
1048 if (ret)
1049 goto err;
1050
1051 n->v.flags = 0;
1052 n->v.parent = cpu_to_le32(parent);
1053 n->v.subvol = cpu_to_le32(snapshot_subvols[i]);
1054 n->v.tree = cpu_to_le32(tree);
1055 n->v.depth = cpu_to_le32(depth);
1056 n->v.btime.lo = cpu_to_le64(bch2_current_time(c));
1057 n->v.btime.hi = 0;
1058
1059 for (j = 0; j < ARRAY_SIZE(n->v.skip); j++)
1060 n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent));
1061
1062 bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32);
1063 SET_BCH_SNAPSHOT_SUBVOL(&n->v, true);
1064
1065 ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
1066 bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0);
1067 if (ret)
1068 goto err;
1069
1070 new_snapids[i] = iter.pos.offset;
1071
1072 mutex_lock(&c->snapshot_table_lock);
1073 snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i];
1074 mutex_unlock(&c->snapshot_table_lock);
1075 }
1076err:
1077 bch2_trans_iter_exit(trans, &iter);
1078 return ret;
1079}
1080
1081/*
1082 * Create new snapshot IDs as children of an existing snapshot ID:
1083 */
1084static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent,
1085 u32 *new_snapids,
1086 u32 *snapshot_subvols,
1087 unsigned nr_snapids)
1088{
1089 struct btree_iter iter;
1090 struct bkey_i_snapshot *n_parent;
1091 int ret = 0;
1092
1093 n_parent = bch2_bkey_get_mut_typed(trans, &iter,
1094 BTREE_ID_snapshots, POS(0, parent),
1095 0, snapshot);
1096 ret = PTR_ERR_OR_ZERO(n_parent);
1097 if (unlikely(ret)) {
1098 if (bch2_err_matches(ret, ENOENT))
1099 bch_err(trans->c, "snapshot %u not found", parent);
1100 return ret;
1101 }
1102
1103 if (n_parent->v.children[0] || n_parent->v.children[1]) {
1104 bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children");
1105 ret = -EINVAL;
1106 goto err;
1107 }
1108
1109 ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree),
1110 new_snapids, snapshot_subvols, nr_snapids);
1111 if (ret)
1112 goto err;
1113
1114 n_parent->v.children[0] = cpu_to_le32(new_snapids[0]);
1115 n_parent->v.children[1] = cpu_to_le32(new_snapids[1]);
1116 n_parent->v.subvol = 0;
1117 SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false);
1118err:
1119 bch2_trans_iter_exit(trans, &iter);
1120 return ret;
1121}
1122
1123/*
1124 * Create a snapshot node that is the root of a new tree:
1125 */
1126static int bch2_snapshot_node_create_tree(struct btree_trans *trans,
1127 u32 *new_snapids,
1128 u32 *snapshot_subvols,
1129 unsigned nr_snapids)
1130{
1131 struct bkey_i_snapshot_tree *n_tree;
1132 int ret;
1133
1134 n_tree = __bch2_snapshot_tree_create(trans);
1135 ret = PTR_ERR_OR_ZERO(n_tree) ?:
1136 create_snapids(trans, 0, n_tree->k.p.offset,
1137 new_snapids, snapshot_subvols, nr_snapids);
1138 if (ret)
1139 return ret;
1140
1141 n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]);
1142 n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]);
1143 return 0;
1144}
1145
1146int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,
1147 u32 *new_snapids,
1148 u32 *snapshot_subvols,
1149 unsigned nr_snapids)
1150{
1151 BUG_ON((parent == 0) != (nr_snapids == 1));
1152 BUG_ON((parent != 0) != (nr_snapids == 2));
1153
1154 return parent
1155 ? bch2_snapshot_node_create_children(trans, parent,
1156 new_snapids, snapshot_subvols, nr_snapids)
1157 : bch2_snapshot_node_create_tree(trans,
1158 new_snapids, snapshot_subvols, nr_snapids);
1159
1160}
1161
1162/*
1163 * If we have an unlinked inode in an internal snapshot node, and the inode
1164 * really has been deleted in all child snapshots, how does this get cleaned up?
1165 *
1166 * first there is the problem of how keys that have been overwritten in all
1167 * child snapshots get deleted (unimplemented?), but inodes may perhaps be
1168 * special?
1169 *
1170 * also: unlinked inode in internal snapshot appears to not be getting deleted
1171 * correctly if inode doesn't exist in leaf snapshots
1172 *
1173 * solution:
1174 *
1175 * for a key in an interior snapshot node that needs work to be done that
1176 * requires it to be mutated: iterate over all descendent leaf nodes and copy
1177 * that key to snapshot leaf nodes, where we can mutate it
1178 */
1179
1180static int snapshot_delete_key(struct btree_trans *trans,
1181 struct btree_iter *iter,
1182 struct bkey_s_c k,
1183 snapshot_id_list *deleted,
1184 snapshot_id_list *equiv_seen,
1185 struct bpos *last_pos)
1186{
1187 struct bch_fs *c = trans->c;
1188 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
1189
1190 if (!bkey_eq(k.k->p, *last_pos))
1191 equiv_seen->nr = 0;
1192 *last_pos = k.k->p;
1193
1194 if (snapshot_list_has_id(deleted, k.k->p.snapshot) ||
1195 snapshot_list_has_id(equiv_seen, equiv)) {
1196 return bch2_btree_delete_at(trans, iter,
1197 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
1198 } else {
1199 return snapshot_list_add(c, equiv_seen, equiv);
1200 }
1201}
1202
1203static int move_key_to_correct_snapshot(struct btree_trans *trans,
1204 struct btree_iter *iter,
1205 struct bkey_s_c k)
1206{
1207 struct bch_fs *c = trans->c;
1208 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
1209
1210 /*
1211 * When we have a linear chain of snapshot nodes, we consider
1212 * those to form an equivalence class: we're going to collapse
1213 * them all down to a single node, and keep the leaf-most node -
1214 * which has the same id as the equivalence class id.
1215 *
1216 * If there are multiple keys in different snapshots at the same
1217 * position, we're only going to keep the one in the newest
1218 * snapshot - the rest have been overwritten and are redundant,
1219 * and for the key we're going to keep we need to move it to the
1220 * equivalance class ID if it's not there already.
1221 */
1222 if (equiv != k.k->p.snapshot) {
1223 struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);
1224 struct btree_iter new_iter;
1225 int ret;
1226
1227 ret = PTR_ERR_OR_ZERO(new);
1228 if (ret)
1229 return ret;
1230
1231 new->k.p.snapshot = equiv;
1232
1233 bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p,
1234 BTREE_ITER_ALL_SNAPSHOTS|
1235 BTREE_ITER_CACHED|
1236 BTREE_ITER_INTENT);
1237
1238 ret = bch2_btree_iter_traverse(&new_iter) ?:
1239 bch2_trans_update(trans, &new_iter, new,
1240 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?:
1241 bch2_btree_delete_at(trans, iter,
1242 BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
1243 bch2_trans_iter_exit(trans, &new_iter);
1244 if (ret)
1245 return ret;
1246 }
1247
1248 return 0;
1249}
1250
1251static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k)
1252{
1253 struct bkey_s_c_snapshot snap;
1254 u32 children[2];
1255 int ret;
1256
1257 if (k.k->type != KEY_TYPE_snapshot)
1258 return 0;
1259
1260 snap = bkey_s_c_to_snapshot(k);
1261 if (BCH_SNAPSHOT_DELETED(snap.v) ||
1262 BCH_SNAPSHOT_SUBVOL(snap.v))
1263 return 0;
1264
1265 children[0] = le32_to_cpu(snap.v->children[0]);
1266 children[1] = le32_to_cpu(snap.v->children[1]);
1267
1268 ret = bch2_snapshot_live(trans, children[0]) ?:
1269 bch2_snapshot_live(trans, children[1]);
1270 if (ret < 0)
1271 return ret;
1272 return !ret;
1273}
1274
1275/*
1276 * For a given snapshot, if it doesn't have a subvolume that points to it, and
1277 * it doesn't have child snapshot nodes - it's now redundant and we can mark it
1278 * as deleted.
1279 */
1280static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k)
1281{
1282 int ret = bch2_snapshot_needs_delete(trans, k);
1283
1284 return ret <= 0
1285 ? ret
1286 : bch2_snapshot_node_set_deleted(trans, k.k->p.offset);
1287}
1288
1289static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n,
1290 snapshot_id_list *skip)
1291{
1292 rcu_read_lock();
1293 while (snapshot_list_has_id(skip, id))
1294 id = __bch2_snapshot_parent(c, id);
1295
1296 while (n--) {
1297 do {
1298 id = __bch2_snapshot_parent(c, id);
1299 } while (snapshot_list_has_id(skip, id));
1300 }
1301 rcu_read_unlock();
1302
1303 return id;
1304}
1305
1306static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans,
1307 struct btree_iter *iter, struct bkey_s_c k,
1308 snapshot_id_list *deleted)
1309{
1310 struct bch_fs *c = trans->c;
1311 u32 nr_deleted_ancestors = 0;
1312 struct bkey_i_snapshot *s;
1313 int ret;
1314
1315 if (k.k->type != KEY_TYPE_snapshot)
1316 return 0;
1317
1318 if (snapshot_list_has_id(deleted, k.k->p.offset))
1319 return 0;
1320
1321 s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot);
1322 ret = PTR_ERR_OR_ZERO(s);
1323 if (ret)
1324 return ret;
1325
1326 darray_for_each(*deleted, i)
1327 nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i);
1328
1329 if (!nr_deleted_ancestors)
1330 return 0;
1331
1332 le32_add_cpu(&s->v.depth, -nr_deleted_ancestors);
1333
1334 if (!s->v.depth) {
1335 s->v.skip[0] = 0;
1336 s->v.skip[1] = 0;
1337 s->v.skip[2] = 0;
1338 } else {
1339 u32 depth = le32_to_cpu(s->v.depth);
1340 u32 parent = bch2_snapshot_parent(c, s->k.p.offset);
1341
1342 for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) {
1343 u32 id = le32_to_cpu(s->v.skip[j]);
1344
1345 if (snapshot_list_has_id(deleted, id)) {
1346 id = bch2_snapshot_nth_parent_skip(c,
1347 parent,
1348 depth > 1
1349 ? get_random_u32_below(depth - 1)
1350 : 0,
1351 deleted);
1352 s->v.skip[j] = cpu_to_le32(id);
1353 }
1354 }
1355
1356 bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32);
1357 }
1358
1359 return bch2_trans_update(trans, iter, &s->k_i, 0);
1360}
1361
1362int bch2_delete_dead_snapshots(struct bch_fs *c)
1363{
1364 struct btree_trans *trans;
1365 snapshot_id_list deleted = { 0 };
1366 snapshot_id_list deleted_interior = { 0 };
1367 u32 id;
1368 int ret = 0;
1369
1370 if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags))
1371 return 0;
1372
1373 if (!test_bit(BCH_FS_started, &c->flags)) {
1374 ret = bch2_fs_read_write_early(c);
1375 bch_err_msg(c, ret, "deleting dead snapshots: error going rw");
1376 if (ret)
1377 return ret;
1378 }
1379
1380 trans = bch2_trans_get(c);
1381
1382 /*
1383 * For every snapshot node: If we have no live children and it's not
1384 * pointed to by a subvolume, delete it:
1385 */
1386 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots,
1387 POS_MIN, 0, k,
1388 NULL, NULL, 0,
1389 bch2_delete_redundant_snapshot(trans, k));
1390 bch_err_msg(c, ret, "deleting redundant snapshots");
1391 if (ret)
1392 goto err;
1393
1394 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1395 POS_MIN, 0, k,
1396 bch2_snapshot_set_equiv(trans, k));
1397 bch_err_msg(c, ret, "in bch2_snapshots_set_equiv");
1398 if (ret)
1399 goto err;
1400
1401 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1402 POS_MIN, 0, k, ({
1403 if (k.k->type != KEY_TYPE_snapshot)
1404 continue;
1405
1406 BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v)
1407 ? snapshot_list_add(c, &deleted, k.k->p.offset)
1408 : 0;
1409 }));
1410 bch_err_msg(c, ret, "walking snapshots");
1411 if (ret)
1412 goto err;
1413
1414 for (id = 0; id < BTREE_ID_NR; id++) {
1415 struct bpos last_pos = POS_MIN;
1416 snapshot_id_list equiv_seen = { 0 };
1417 struct disk_reservation res = { 0 };
1418
1419 if (!btree_type_has_snapshots(id))
1420 continue;
1421
1422 /*
1423 * deleted inodes btree is maintained by a trigger on the inodes
1424 * btree - no work for us to do here, and it's not safe to scan
1425 * it because we'll see out of date keys due to the btree write
1426 * buffer:
1427 */
1428 if (id == BTREE_ID_deleted_inodes)
1429 continue;
1430
1431 ret = for_each_btree_key_commit(trans, iter,
1432 id, POS_MIN,
1433 BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
1434 &res, NULL, BCH_TRANS_COMMIT_no_enospc,
1435 snapshot_delete_key(trans, &iter, k, &deleted, &equiv_seen, &last_pos)) ?:
1436 for_each_btree_key_commit(trans, iter,
1437 id, POS_MIN,
1438 BTREE_ITER_PREFETCH|BTREE_ITER_ALL_SNAPSHOTS, k,
1439 &res, NULL, BCH_TRANS_COMMIT_no_enospc,
1440 move_key_to_correct_snapshot(trans, &iter, k));
1441
1442 bch2_disk_reservation_put(c, &res);
1443 darray_exit(&equiv_seen);
1444
1445 bch_err_msg(c, ret, "deleting keys from dying snapshots");
1446 if (ret)
1447 goto err;
1448 }
1449
1450 bch2_trans_unlock(trans);
1451 down_write(&c->snapshot_create_lock);
1452
1453 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1454 POS_MIN, 0, k, ({
1455 u32 snapshot = k.k->p.offset;
1456 u32 equiv = bch2_snapshot_equiv(c, snapshot);
1457
1458 equiv != snapshot
1459 ? snapshot_list_add(c, &deleted_interior, snapshot)
1460 : 0;
1461 }));
1462
1463 bch_err_msg(c, ret, "walking snapshots");
1464 if (ret)
1465 goto err_create_lock;
1466
1467 /*
1468 * Fixing children of deleted snapshots can't be done completely
1469 * atomically, if we crash between here and when we delete the interior
1470 * nodes some depth fields will be off:
1471 */
1472 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN,
1473 BTREE_ITER_INTENT, k,
1474 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
1475 bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior));
1476 if (ret)
1477 goto err_create_lock;
1478
1479 darray_for_each(deleted, i) {
1480 ret = commit_do(trans, NULL, NULL, 0,
1481 bch2_snapshot_node_delete(trans, *i));
1482 bch_err_msg(c, ret, "deleting snapshot %u", *i);
1483 if (ret)
1484 goto err_create_lock;
1485 }
1486
1487 darray_for_each(deleted_interior, i) {
1488 ret = commit_do(trans, NULL, NULL, 0,
1489 bch2_snapshot_node_delete(trans, *i));
1490 bch_err_msg(c, ret, "deleting snapshot %u", *i);
1491 if (ret)
1492 goto err_create_lock;
1493 }
1494err_create_lock:
1495 up_write(&c->snapshot_create_lock);
1496err:
1497 darray_exit(&deleted_interior);
1498 darray_exit(&deleted);
1499 bch2_trans_put(trans);
1500 bch_err_fn(c, ret);
1501 return ret;
1502}
1503
1504void bch2_delete_dead_snapshots_work(struct work_struct *work)
1505{
1506 struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work);
1507
1508 bch2_delete_dead_snapshots(c);
1509 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
1510}
1511
1512void bch2_delete_dead_snapshots_async(struct bch_fs *c)
1513{
1514 if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) &&
1515 !queue_work(c->write_ref_wq, &c->snapshot_delete_work))
1516 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
1517}
1518
1519int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans,
1520 enum btree_id id,
1521 struct bpos pos)
1522{
1523 struct bch_fs *c = trans->c;
1524 struct btree_iter iter;
1525 struct bkey_s_c k;
1526 int ret;
1527
1528 bch2_trans_iter_init(trans, &iter, id, pos,
1529 BTREE_ITER_NOT_EXTENTS|
1530 BTREE_ITER_ALL_SNAPSHOTS);
1531 while (1) {
1532 k = bch2_btree_iter_prev(&iter);
1533 ret = bkey_err(k);
1534 if (ret)
1535 break;
1536
1537 if (!k.k)
1538 break;
1539
1540 if (!bkey_eq(pos, k.k->p))
1541 break;
1542
1543 if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) {
1544 ret = 1;
1545 break;
1546 }
1547 }
1548 bch2_trans_iter_exit(trans, &iter);
1549
1550 return ret;
1551}
1552
1553static u32 bch2_snapshot_smallest_child(struct bch_fs *c, u32 id)
1554{
1555 const struct snapshot_t *s = snapshot_t(c, id);
1556
1557 return s->children[1] ?: s->children[0];
1558}
1559
1560static u32 bch2_snapshot_smallest_descendent(struct bch_fs *c, u32 id)
1561{
1562 u32 child;
1563
1564 while ((child = bch2_snapshot_smallest_child(c, id)))
1565 id = child;
1566 return id;
1567}
1568
1569static int bch2_propagate_key_to_snapshot_leaf(struct btree_trans *trans,
1570 enum btree_id btree,
1571 struct bkey_s_c interior_k,
1572 u32 leaf_id, struct bpos *new_min_pos)
1573{
1574 struct btree_iter iter;
1575 struct bpos pos = interior_k.k->p;
1576 struct bkey_s_c k;
1577 struct bkey_i *new;
1578 int ret;
1579
1580 pos.snapshot = leaf_id;
1581
1582 bch2_trans_iter_init(trans, &iter, btree, pos, BTREE_ITER_INTENT);
1583 k = bch2_btree_iter_peek_slot(&iter);
1584 ret = bkey_err(k);
1585 if (ret)
1586 goto out;
1587
1588 /* key already overwritten in this snapshot? */
1589 if (k.k->p.snapshot != interior_k.k->p.snapshot)
1590 goto out;
1591
1592 if (bpos_eq(*new_min_pos, POS_MIN)) {
1593 *new_min_pos = k.k->p;
1594 new_min_pos->snapshot = leaf_id;
1595 }
1596
1597 new = bch2_bkey_make_mut_noupdate(trans, interior_k);
1598 ret = PTR_ERR_OR_ZERO(new);
1599 if (ret)
1600 goto out;
1601
1602 new->k.p.snapshot = leaf_id;
1603 ret = bch2_trans_update(trans, &iter, new, 0);
1604out:
1605 bch2_trans_iter_exit(trans, &iter);
1606 return ret;
1607}
1608
1609int bch2_propagate_key_to_snapshot_leaves(struct btree_trans *trans,
1610 enum btree_id btree,
1611 struct bkey_s_c k,
1612 struct bpos *new_min_pos)
1613{
1614 struct bch_fs *c = trans->c;
1615 struct bkey_buf sk;
1616 u32 restart_count = trans->restart_count;
1617 int ret = 0;
1618
1619 bch2_bkey_buf_init(&sk);
1620 bch2_bkey_buf_reassemble(&sk, c, k);
1621 k = bkey_i_to_s_c(sk.k);
1622
1623 *new_min_pos = POS_MIN;
1624
1625 for (u32 id = bch2_snapshot_smallest_descendent(c, k.k->p.snapshot);
1626 id < k.k->p.snapshot;
1627 id++) {
1628 if (!bch2_snapshot_is_ancestor(c, id, k.k->p.snapshot) ||
1629 !bch2_snapshot_is_leaf(c, id))
1630 continue;
1631again:
1632 ret = btree_trans_too_many_iters(trans) ?:
1633 bch2_propagate_key_to_snapshot_leaf(trans, btree, k, id, new_min_pos) ?:
1634 bch2_trans_commit(trans, NULL, NULL, 0);
1635 if (ret && bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
1636 bch2_trans_begin(trans);
1637 goto again;
1638 }
1639
1640 if (ret)
1641 break;
1642 }
1643
1644 bch2_bkey_buf_exit(&sk, c);
1645
1646 return ret ?: trans_was_restarted(trans, restart_count);
1647}
1648
1649static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k)
1650{
1651 struct bch_fs *c = trans->c;
1652 struct bkey_s_c_snapshot snap;
1653 int ret = 0;
1654
1655 if (k.k->type != KEY_TYPE_snapshot)
1656 return 0;
1657
1658 snap = bkey_s_c_to_snapshot(k);
1659 if (BCH_SNAPSHOT_DELETED(snap.v) ||
1660 bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset ||
1661 (ret = bch2_snapshot_needs_delete(trans, k)) > 0) {
1662 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
1663 return 0;
1664 }
1665
1666 return ret;
1667}
1668
1669int bch2_snapshots_read(struct bch_fs *c)
1670{
1671 int ret = bch2_trans_run(c,
1672 for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1673 POS_MIN, 0, k,
1674 __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?:
1675 bch2_snapshot_set_equiv(trans, k) ?:
1676 bch2_check_snapshot_needs_deletion(trans, k)) ?:
1677 for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1678 POS_MIN, 0, k,
1679 (set_is_ancestor_bitmap(c, k.k->p.offset), 0)));
1680 bch_err_fn(c, ret);
1681 return ret;
1682}
1683
1684void bch2_fs_snapshots_exit(struct bch_fs *c)
1685{
1686 kvfree(rcu_dereference_protected(c->snapshots, true));
1687}