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 "recovery_passes.h"
12 #include "snapshot.h"
13
14 #include <linux/random.h>
15
16 /*
17 * Snapshot trees:
18 *
19 * Keys in BTREE_ID_snapshot_trees identify a whole tree of snapshot nodes; they
20 * exist to provide a stable identifier for the whole lifetime of a snapshot
21 * tree.
22 */
23
24 void bch2_snapshot_tree_to_text(struct printbuf *out, struct bch_fs *c,
25 struct bkey_s_c k)
26 {
27 struct bkey_s_c_snapshot_tree t = bkey_s_c_to_snapshot_tree(k);
28
29 prt_printf(out, "subvol %u root snapshot %u",
30 le32_to_cpu(t.v->master_subvol),
31 le32_to_cpu(t.v->root_snapshot));
32 }
33
34 int bch2_snapshot_tree_validate(struct bch_fs *c, struct bkey_s_c k,
35 enum bch_validate_flags flags)
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)),
41 c, snapshot_tree_pos_bad,
42 "bad pos");
43 fsck_err:
44 return ret;
45 }
46
47 int 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
58 struct 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
77 static 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
94 static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor)
95 {
96 while (id && id < ancestor) {
97 const struct snapshot_t *s = __snapshot_t(t, id);
98 id = s ? s->parent : 0;
99 }
100 return id == ancestor;
101 }
102
103 static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)
104 {
105 rcu_read_lock();
106 bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor);
107 rcu_read_unlock();
108
109 return ret;
110 }
111
112 static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)
113 {
114 const struct snapshot_t *s = __snapshot_t(t, id);
115 if (!s)
116 return 0;
117
118 if (s->skip[2] <= ancestor)
119 return s->skip[2];
120 if (s->skip[1] <= ancestor)
121 return s->skip[1];
122 if (s->skip[0] <= ancestor)
123 return s->skip[0];
124 return s->parent;
125 }
126
127 static bool test_ancestor_bitmap(struct snapshot_table *t, u32 id, u32 ancestor)
128 {
129 const struct snapshot_t *s = __snapshot_t(t, id);
130 if (!s)
131 return false;
132
133 return test_bit(ancestor - id - 1, s->is_ancestor);
134 }
135
136 bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
137 {
138 bool ret;
139
140 rcu_read_lock();
141 struct snapshot_table *t = rcu_dereference(c->snapshots);
142
143 if (unlikely(c->recovery_pass_done < BCH_RECOVERY_PASS_check_snapshots)) {
144 ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor);
145 goto out;
146 }
147
148 while (id && id < ancestor - IS_ANCESTOR_BITMAP)
149 id = get_ancestor_below(t, id, ancestor);
150
151 ret = id && id < ancestor
152 ? test_ancestor_bitmap(t, id, ancestor)
153 : id == ancestor;
154
155 EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));
156 out:
157 rcu_read_unlock();
158
159 return ret;
160 }
161
162 static noinline struct snapshot_t *__snapshot_t_mut(struct bch_fs *c, u32 id)
163 {
164 size_t idx = U32_MAX - id;
165 struct snapshot_table *new, *old;
166
167 size_t new_bytes = kmalloc_size_roundup(struct_size(new, s, idx + 1));
168 size_t new_size = (new_bytes - sizeof(*new)) / sizeof(new->s[0]);
169
170 if (unlikely(new_bytes > INT_MAX))
171 return NULL;
172
173 new = kvzalloc(new_bytes, GFP_KERNEL);
174 if (!new)
175 return NULL;
176
177 new->nr = new_size;
178
179 old = rcu_dereference_protected(c->snapshots, true);
180 if (old)
181 memcpy(new->s, old->s, sizeof(old->s[0]) * old->nr);
182
183 rcu_assign_pointer(c->snapshots, new);
184 kvfree_rcu(old, rcu);
185
186 return &rcu_dereference_protected(c->snapshots,
187 lockdep_is_held(&c->snapshot_table_lock))->s[idx];
188 }
189
190 static inline struct snapshot_t *snapshot_t_mut(struct bch_fs *c, u32 id)
191 {
192 size_t idx = U32_MAX - id;
193 struct snapshot_table *table =
194 rcu_dereference_protected(c->snapshots,
195 lockdep_is_held(&c->snapshot_table_lock));
196
197 lockdep_assert_held(&c->snapshot_table_lock);
198
199 if (likely(table && idx < table->nr))
200 return &table->s[idx];
201
202 return __snapshot_t_mut(c, id);
203 }
204
205 void bch2_snapshot_to_text(struct printbuf *out, struct bch_fs *c,
206 struct bkey_s_c k)
207 {
208 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(k);
209
210 prt_printf(out, "is_subvol %llu deleted %llu parent %10u children %10u %10u subvol %u tree %u",
211 BCH_SNAPSHOT_SUBVOL(s.v),
212 BCH_SNAPSHOT_DELETED(s.v),
213 le32_to_cpu(s.v->parent),
214 le32_to_cpu(s.v->children[0]),
215 le32_to_cpu(s.v->children[1]),
216 le32_to_cpu(s.v->subvol),
217 le32_to_cpu(s.v->tree));
218
219 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, depth))
220 prt_printf(out, " depth %u skiplist %u %u %u",
221 le32_to_cpu(s.v->depth),
222 le32_to_cpu(s.v->skip[0]),
223 le32_to_cpu(s.v->skip[1]),
224 le32_to_cpu(s.v->skip[2]));
225 }
226
227 int bch2_snapshot_validate(struct bch_fs *c, struct bkey_s_c k,
228 enum bch_validate_flags flags)
229 {
230 struct bkey_s_c_snapshot s;
231 u32 i, id;
232 int ret = 0;
233
234 bkey_fsck_err_on(bkey_gt(k.k->p, POS(0, U32_MAX)) ||
235 bkey_lt(k.k->p, POS(0, 1)),
236 c, snapshot_pos_bad,
237 "bad pos");
238
239 s = bkey_s_c_to_snapshot(k);
240
241 id = le32_to_cpu(s.v->parent);
242 bkey_fsck_err_on(id && id <= k.k->p.offset,
243 c, snapshot_parent_bad,
244 "bad parent node (%u <= %llu)",
245 id, k.k->p.offset);
246
247 bkey_fsck_err_on(le32_to_cpu(s.v->children[0]) < le32_to_cpu(s.v->children[1]),
248 c, snapshot_children_not_normalized,
249 "children not normalized");
250
251 bkey_fsck_err_on(s.v->children[0] && s.v->children[0] == s.v->children[1],
252 c, snapshot_child_duplicate,
253 "duplicate child nodes");
254
255 for (i = 0; i < 2; i++) {
256 id = le32_to_cpu(s.v->children[i]);
257
258 bkey_fsck_err_on(id >= k.k->p.offset,
259 c, snapshot_child_bad,
260 "bad child node (%u >= %llu)",
261 id, k.k->p.offset);
262 }
263
264 if (bkey_val_bytes(k.k) > offsetof(struct bch_snapshot, skip)) {
265 bkey_fsck_err_on(le32_to_cpu(s.v->skip[0]) > le32_to_cpu(s.v->skip[1]) ||
266 le32_to_cpu(s.v->skip[1]) > le32_to_cpu(s.v->skip[2]),
267 c, snapshot_skiplist_not_normalized,
268 "skiplist not normalized");
269
270 for (i = 0; i < ARRAY_SIZE(s.v->skip); i++) {
271 id = le32_to_cpu(s.v->skip[i]);
272
273 bkey_fsck_err_on(id && id < le32_to_cpu(s.v->parent),
274 c, snapshot_skiplist_bad,
275 "bad skiplist node %u", id);
276 }
277 }
278 fsck_err:
279 return ret;
280 }
281
282 static void __set_is_ancestor_bitmap(struct bch_fs *c, u32 id)
283 {
284 struct snapshot_t *t = snapshot_t_mut(c, id);
285 u32 parent = id;
286
287 while ((parent = bch2_snapshot_parent_early(c, parent)) &&
288 parent - id - 1 < IS_ANCESTOR_BITMAP)
289 __set_bit(parent - id - 1, t->is_ancestor);
290 }
291
292 static void set_is_ancestor_bitmap(struct bch_fs *c, u32 id)
293 {
294 mutex_lock(&c->snapshot_table_lock);
295 __set_is_ancestor_bitmap(c, id);
296 mutex_unlock(&c->snapshot_table_lock);
297 }
298
299 static int __bch2_mark_snapshot(struct btree_trans *trans,
300 enum btree_id btree, unsigned level,
301 struct bkey_s_c old, struct bkey_s_c new,
302 enum btree_iter_update_trigger_flags flags)
303 {
304 struct bch_fs *c = trans->c;
305 struct snapshot_t *t;
306 u32 id = new.k->p.offset;
307 int ret = 0;
308
309 mutex_lock(&c->snapshot_table_lock);
310
311 t = snapshot_t_mut(c, id);
312 if (!t) {
313 ret = -BCH_ERR_ENOMEM_mark_snapshot;
314 goto err;
315 }
316
317 if (new.k->type == KEY_TYPE_snapshot) {
318 struct bkey_s_c_snapshot s = bkey_s_c_to_snapshot(new);
319
320 t->parent = le32_to_cpu(s.v->parent);
321 t->children[0] = le32_to_cpu(s.v->children[0]);
322 t->children[1] = le32_to_cpu(s.v->children[1]);
323 t->subvol = BCH_SNAPSHOT_SUBVOL(s.v) ? le32_to_cpu(s.v->subvol) : 0;
324 t->tree = le32_to_cpu(s.v->tree);
325
326 if (bkey_val_bytes(s.k) > offsetof(struct bch_snapshot, depth)) {
327 t->depth = le32_to_cpu(s.v->depth);
328 t->skip[0] = le32_to_cpu(s.v->skip[0]);
329 t->skip[1] = le32_to_cpu(s.v->skip[1]);
330 t->skip[2] = le32_to_cpu(s.v->skip[2]);
331 } else {
332 t->depth = 0;
333 t->skip[0] = 0;
334 t->skip[1] = 0;
335 t->skip[2] = 0;
336 }
337
338 __set_is_ancestor_bitmap(c, id);
339
340 if (BCH_SNAPSHOT_DELETED(s.v)) {
341 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
342 if (c->curr_recovery_pass > BCH_RECOVERY_PASS_delete_dead_snapshots)
343 bch2_delete_dead_snapshots_async(c);
344 }
345 } else {
346 memset(t, 0, sizeof(*t));
347 }
348 err:
349 mutex_unlock(&c->snapshot_table_lock);
350 return ret;
351 }
352
353 int bch2_mark_snapshot(struct btree_trans *trans,
354 enum btree_id btree, unsigned level,
355 struct bkey_s_c old, struct bkey_s new,
356 enum btree_iter_update_trigger_flags flags)
357 {
358 return __bch2_mark_snapshot(trans, btree, level, old, new.s_c, flags);
359 }
360
361 int bch2_snapshot_lookup(struct btree_trans *trans, u32 id,
362 struct bch_snapshot *s)
363 {
364 return bch2_bkey_get_val_typed(trans, BTREE_ID_snapshots, POS(0, id),
365 BTREE_ITER_with_updates, snapshot, s);
366 }
367
368 static int bch2_snapshot_live(struct btree_trans *trans, u32 id)
369 {
370 struct bch_snapshot v;
371 int ret;
372
373 if (!id)
374 return 0;
375
376 ret = bch2_snapshot_lookup(trans, id, &v);
377 if (bch2_err_matches(ret, ENOENT))
378 bch_err(trans->c, "snapshot node %u not found", id);
379 if (ret)
380 return ret;
381
382 return !BCH_SNAPSHOT_DELETED(&v);
383 }
384
385 /*
386 * If @k is a snapshot with just one live child, it's part of a linear chain,
387 * which we consider to be an equivalence class: and then after snapshot
388 * deletion cleanup, there should only be a single key at a given position in
389 * this equivalence class.
390 *
391 * This sets the equivalence class of @k to be the child's equivalence class, if
392 * it's part of such a linear chain: this correctly sets equivalence classes on
393 * startup if we run leaf to root (i.e. in natural key order).
394 */
395 static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
396 {
397 struct bch_fs *c = trans->c;
398 unsigned i, nr_live = 0, live_idx = 0;
399 struct bkey_s_c_snapshot snap;
400 u32 id = k.k->p.offset, child[2];
401
402 if (k.k->type != KEY_TYPE_snapshot)
403 return 0;
404
405 snap = bkey_s_c_to_snapshot(k);
406
407 child[0] = le32_to_cpu(snap.v->children[0]);
408 child[1] = le32_to_cpu(snap.v->children[1]);
409
410 for (i = 0; i < 2; i++) {
411 int ret = bch2_snapshot_live(trans, child[i]);
412
413 if (ret < 0)
414 return ret;
415
416 if (ret)
417 live_idx = i;
418 nr_live += ret;
419 }
420
421 mutex_lock(&c->snapshot_table_lock);
422
423 snapshot_t_mut(c, id)->equiv = nr_live == 1
424 ? snapshot_t_mut(c, child[live_idx])->equiv
425 : id;
426
427 mutex_unlock(&c->snapshot_table_lock);
428
429 return 0;
430 }
431
432 /* fsck: */
433
434 static u32 bch2_snapshot_child(struct bch_fs *c, u32 id, unsigned child)
435 {
436 return snapshot_t(c, id)->children[child];
437 }
438
439 static u32 bch2_snapshot_left_child(struct bch_fs *c, u32 id)
440 {
441 return bch2_snapshot_child(c, id, 0);
442 }
443
444 static u32 bch2_snapshot_right_child(struct bch_fs *c, u32 id)
445 {
446 return bch2_snapshot_child(c, id, 1);
447 }
448
449 static u32 bch2_snapshot_tree_next(struct bch_fs *c, u32 id)
450 {
451 u32 n, parent;
452
453 n = bch2_snapshot_left_child(c, id);
454 if (n)
455 return n;
456
457 while ((parent = bch2_snapshot_parent(c, id))) {
458 n = bch2_snapshot_right_child(c, parent);
459 if (n && n != id)
460 return n;
461 id = parent;
462 }
463
464 return 0;
465 }
466
467 static u32 bch2_snapshot_tree_oldest_subvol(struct bch_fs *c, u32 snapshot_root)
468 {
469 u32 id = snapshot_root;
470 u32 subvol = 0, s;
471
472 while (id) {
473 s = snapshot_t(c, id)->subvol;
474
475 if (s && (!subvol || s < subvol))
476 subvol = s;
477
478 id = bch2_snapshot_tree_next(c, id);
479 }
480
481 return subvol;
482 }
483
484 static int bch2_snapshot_tree_master_subvol(struct btree_trans *trans,
485 u32 snapshot_root, u32 *subvol_id)
486 {
487 struct bch_fs *c = trans->c;
488 struct btree_iter iter;
489 struct bkey_s_c k;
490 bool found = false;
491 int ret;
492
493 for_each_btree_key_norestart(trans, iter, BTREE_ID_subvolumes, POS_MIN,
494 0, k, ret) {
495 if (k.k->type != KEY_TYPE_subvolume)
496 continue;
497
498 struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
499 if (!bch2_snapshot_is_ancestor(c, le32_to_cpu(s.v->snapshot), snapshot_root))
500 continue;
501 if (!BCH_SUBVOLUME_SNAP(s.v)) {
502 *subvol_id = s.k->p.offset;
503 found = true;
504 break;
505 }
506 }
507
508 bch2_trans_iter_exit(trans, &iter);
509
510 if (!ret && !found) {
511 struct bkey_i_subvolume *u;
512
513 *subvol_id = bch2_snapshot_tree_oldest_subvol(c, snapshot_root);
514
515 u = bch2_bkey_get_mut_typed(trans, &iter,
516 BTREE_ID_subvolumes, POS(0, *subvol_id),
517 0, subvolume);
518 ret = PTR_ERR_OR_ZERO(u);
519 if (ret)
520 return ret;
521
522 SET_BCH_SUBVOLUME_SNAP(&u->v, false);
523 }
524
525 return ret;
526 }
527
528 static int check_snapshot_tree(struct btree_trans *trans,
529 struct btree_iter *iter,
530 struct bkey_s_c k)
531 {
532 struct bch_fs *c = trans->c;
533 struct bkey_s_c_snapshot_tree st;
534 struct bch_snapshot s;
535 struct bch_subvolume subvol;
536 struct printbuf buf = PRINTBUF;
537 u32 root_id;
538 int ret;
539
540 if (k.k->type != KEY_TYPE_snapshot_tree)
541 return 0;
542
543 st = bkey_s_c_to_snapshot_tree(k);
544 root_id = le32_to_cpu(st.v->root_snapshot);
545
546 ret = bch2_snapshot_lookup(trans, root_id, &s);
547 if (ret && !bch2_err_matches(ret, ENOENT))
548 goto err;
549
550 if (fsck_err_on(ret ||
551 root_id != bch2_snapshot_root(c, root_id) ||
552 st.k->p.offset != le32_to_cpu(s.tree),
553 trans, snapshot_tree_to_missing_snapshot,
554 "snapshot tree points to missing/incorrect snapshot:\n %s",
555 (bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
556 ret = bch2_btree_delete_at(trans, iter, 0);
557 goto err;
558 }
559
560 ret = bch2_subvolume_get(trans, le32_to_cpu(st.v->master_subvol),
561 false, 0, &subvol);
562 if (ret && !bch2_err_matches(ret, ENOENT))
563 goto err;
564
565 if (fsck_err_on(ret,
566 trans, snapshot_tree_to_missing_subvol,
567 "snapshot tree points to missing subvolume:\n %s",
568 (printbuf_reset(&buf),
569 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
570 fsck_err_on(!bch2_snapshot_is_ancestor(c,
571 le32_to_cpu(subvol.snapshot),
572 root_id),
573 trans, snapshot_tree_to_wrong_subvol,
574 "snapshot tree points to subvolume that does not point to snapshot in this tree:\n %s",
575 (printbuf_reset(&buf),
576 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
577 fsck_err_on(BCH_SUBVOLUME_SNAP(&subvol),
578 trans, snapshot_tree_to_snapshot_subvol,
579 "snapshot tree points to snapshot subvolume:\n %s",
580 (printbuf_reset(&buf),
581 bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf))) {
582 struct bkey_i_snapshot_tree *u;
583 u32 subvol_id;
584
585 ret = bch2_snapshot_tree_master_subvol(trans, root_id, &subvol_id);
586 bch_err_fn(c, ret);
587
588 if (bch2_err_matches(ret, ENOENT)) { /* nothing to be done here */
589 ret = 0;
590 goto err;
591 }
592
593 if (ret)
594 goto err;
595
596 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot_tree);
597 ret = PTR_ERR_OR_ZERO(u);
598 if (ret)
599 goto err;
600
601 u->v.master_subvol = cpu_to_le32(subvol_id);
602 st = snapshot_tree_i_to_s_c(u);
603 }
604 err:
605 fsck_err:
606 printbuf_exit(&buf);
607 return ret;
608 }
609
610 /*
611 * For each snapshot_tree, make sure it points to the root of a snapshot tree
612 * and that snapshot entry points back to it, or delete it.
613 *
614 * And, make sure it points to a subvolume within that snapshot tree, or correct
615 * it to point to the oldest subvolume within that snapshot tree.
616 */
617 int bch2_check_snapshot_trees(struct bch_fs *c)
618 {
619 int ret = bch2_trans_run(c,
620 for_each_btree_key_commit(trans, iter,
621 BTREE_ID_snapshot_trees, POS_MIN,
622 BTREE_ITER_prefetch, k,
623 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
624 check_snapshot_tree(trans, &iter, k)));
625 bch_err_fn(c, ret);
626 return ret;
627 }
628
629 /*
630 * Look up snapshot tree for @tree_id and find root,
631 * make sure @snap_id is a descendent:
632 */
633 static int snapshot_tree_ptr_good(struct btree_trans *trans,
634 u32 snap_id, u32 tree_id)
635 {
636 struct bch_snapshot_tree s_t;
637 int ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
638
639 if (bch2_err_matches(ret, ENOENT))
640 return 0;
641 if (ret)
642 return ret;
643
644 return bch2_snapshot_is_ancestor_early(trans->c, snap_id, le32_to_cpu(s_t.root_snapshot));
645 }
646
647 u32 bch2_snapshot_skiplist_get(struct bch_fs *c, u32 id)
648 {
649 const struct snapshot_t *s;
650
651 if (!id)
652 return 0;
653
654 rcu_read_lock();
655 s = snapshot_t(c, id);
656 if (s->parent)
657 id = bch2_snapshot_nth_parent(c, id, get_random_u32_below(s->depth));
658 rcu_read_unlock();
659
660 return id;
661 }
662
663 static int snapshot_skiplist_good(struct btree_trans *trans, u32 id, struct bch_snapshot s)
664 {
665 unsigned i;
666
667 for (i = 0; i < 3; i++)
668 if (!s.parent) {
669 if (s.skip[i])
670 return false;
671 } else {
672 if (!bch2_snapshot_is_ancestor_early(trans->c, id, le32_to_cpu(s.skip[i])))
673 return false;
674 }
675
676 return true;
677 }
678
679 /*
680 * snapshot_tree pointer was incorrect: look up root snapshot node, make sure
681 * its snapshot_tree pointer is correct (allocate new one if necessary), then
682 * update this node's pointer to root node's pointer:
683 */
684 static int snapshot_tree_ptr_repair(struct btree_trans *trans,
685 struct btree_iter *iter,
686 struct bkey_s_c k,
687 struct bch_snapshot *s)
688 {
689 struct bch_fs *c = trans->c;
690 struct btree_iter root_iter;
691 struct bch_snapshot_tree s_t;
692 struct bkey_s_c_snapshot root;
693 struct bkey_i_snapshot *u;
694 u32 root_id = bch2_snapshot_root(c, k.k->p.offset), tree_id;
695 int ret;
696
697 root = bch2_bkey_get_iter_typed(trans, &root_iter,
698 BTREE_ID_snapshots, POS(0, root_id),
699 BTREE_ITER_with_updates, snapshot);
700 ret = bkey_err(root);
701 if (ret)
702 goto err;
703
704 tree_id = le32_to_cpu(root.v->tree);
705
706 ret = bch2_snapshot_tree_lookup(trans, tree_id, &s_t);
707 if (ret && !bch2_err_matches(ret, ENOENT))
708 return ret;
709
710 if (ret || le32_to_cpu(s_t.root_snapshot) != root_id) {
711 u = bch2_bkey_make_mut_typed(trans, &root_iter, &root.s_c, 0, snapshot);
712 ret = PTR_ERR_OR_ZERO(u) ?:
713 bch2_snapshot_tree_create(trans, root_id,
714 bch2_snapshot_tree_oldest_subvol(c, root_id),
715 &tree_id);
716 if (ret)
717 goto err;
718
719 u->v.tree = cpu_to_le32(tree_id);
720 if (k.k->p.offset == root_id)
721 *s = u->v;
722 }
723
724 if (k.k->p.offset != root_id) {
725 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
726 ret = PTR_ERR_OR_ZERO(u);
727 if (ret)
728 goto err;
729
730 u->v.tree = cpu_to_le32(tree_id);
731 *s = u->v;
732 }
733 err:
734 bch2_trans_iter_exit(trans, &root_iter);
735 return ret;
736 }
737
738 static int check_snapshot(struct btree_trans *trans,
739 struct btree_iter *iter,
740 struct bkey_s_c k)
741 {
742 struct bch_fs *c = trans->c;
743 struct bch_snapshot s;
744 struct bch_subvolume subvol;
745 struct bch_snapshot v;
746 struct bkey_i_snapshot *u;
747 u32 parent_id = bch2_snapshot_parent_early(c, k.k->p.offset);
748 u32 real_depth;
749 struct printbuf buf = PRINTBUF;
750 u32 i, id;
751 int ret = 0;
752
753 if (k.k->type != KEY_TYPE_snapshot)
754 return 0;
755
756 memset(&s, 0, sizeof(s));
757 memcpy(&s, k.v, min(sizeof(s), bkey_val_bytes(k.k)));
758
759 id = le32_to_cpu(s.parent);
760 if (id) {
761 ret = bch2_snapshot_lookup(trans, id, &v);
762 if (bch2_err_matches(ret, ENOENT))
763 bch_err(c, "snapshot with nonexistent parent:\n %s",
764 (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
765 if (ret)
766 goto err;
767
768 if (le32_to_cpu(v.children[0]) != k.k->p.offset &&
769 le32_to_cpu(v.children[1]) != k.k->p.offset) {
770 bch_err(c, "snapshot parent %u missing pointer to child %llu",
771 id, k.k->p.offset);
772 ret = -EINVAL;
773 goto err;
774 }
775 }
776
777 for (i = 0; i < 2 && s.children[i]; i++) {
778 id = le32_to_cpu(s.children[i]);
779
780 ret = bch2_snapshot_lookup(trans, id, &v);
781 if (bch2_err_matches(ret, ENOENT))
782 bch_err(c, "snapshot node %llu has nonexistent child %u",
783 k.k->p.offset, id);
784 if (ret)
785 goto err;
786
787 if (le32_to_cpu(v.parent) != k.k->p.offset) {
788 bch_err(c, "snapshot child %u has wrong parent (got %u should be %llu)",
789 id, le32_to_cpu(v.parent), k.k->p.offset);
790 ret = -EINVAL;
791 goto err;
792 }
793 }
794
795 bool should_have_subvol = BCH_SNAPSHOT_SUBVOL(&s) &&
796 !BCH_SNAPSHOT_DELETED(&s);
797
798 if (should_have_subvol) {
799 id = le32_to_cpu(s.subvol);
800 ret = bch2_subvolume_get(trans, id, 0, false, &subvol);
801 if (bch2_err_matches(ret, ENOENT))
802 bch_err(c, "snapshot points to nonexistent subvolume:\n %s",
803 (bch2_bkey_val_to_text(&buf, c, k), buf.buf));
804 if (ret)
805 goto err;
806
807 if (BCH_SNAPSHOT_SUBVOL(&s) != (le32_to_cpu(subvol.snapshot) == k.k->p.offset)) {
808 bch_err(c, "snapshot node %llu has wrong BCH_SNAPSHOT_SUBVOL",
809 k.k->p.offset);
810 ret = -EINVAL;
811 goto err;
812 }
813 } else {
814 if (fsck_err_on(s.subvol,
815 trans, snapshot_should_not_have_subvol,
816 "snapshot should not point to subvol:\n %s",
817 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
818 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
819 ret = PTR_ERR_OR_ZERO(u);
820 if (ret)
821 goto err;
822
823 u->v.subvol = 0;
824 s = u->v;
825 }
826 }
827
828 ret = snapshot_tree_ptr_good(trans, k.k->p.offset, le32_to_cpu(s.tree));
829 if (ret < 0)
830 goto err;
831
832 if (fsck_err_on(!ret,
833 trans, snapshot_to_bad_snapshot_tree,
834 "snapshot points to missing/incorrect tree:\n %s",
835 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
836 ret = snapshot_tree_ptr_repair(trans, iter, k, &s);
837 if (ret)
838 goto err;
839 }
840 ret = 0;
841
842 real_depth = bch2_snapshot_depth(c, parent_id);
843
844 if (fsck_err_on(le32_to_cpu(s.depth) != real_depth,
845 trans, snapshot_bad_depth,
846 "snapshot with incorrect depth field, should be %u:\n %s",
847 real_depth, (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
848 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
849 ret = PTR_ERR_OR_ZERO(u);
850 if (ret)
851 goto err;
852
853 u->v.depth = cpu_to_le32(real_depth);
854 s = u->v;
855 }
856
857 ret = snapshot_skiplist_good(trans, k.k->p.offset, s);
858 if (ret < 0)
859 goto err;
860
861 if (fsck_err_on(!ret,
862 trans, snapshot_bad_skiplist,
863 "snapshot with bad skiplist field:\n %s",
864 (bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
865 u = bch2_bkey_make_mut_typed(trans, iter, &k, 0, snapshot);
866 ret = PTR_ERR_OR_ZERO(u);
867 if (ret)
868 goto err;
869
870 for (i = 0; i < ARRAY_SIZE(u->v.skip); i++)
871 u->v.skip[i] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent_id));
872
873 bubble_sort(u->v.skip, ARRAY_SIZE(u->v.skip), cmp_le32);
874 s = u->v;
875 }
876 ret = 0;
877 err:
878 fsck_err:
879 printbuf_exit(&buf);
880 return ret;
881 }
882
883 int bch2_check_snapshots(struct bch_fs *c)
884 {
885 /*
886 * We iterate backwards as checking/fixing the depth field requires that
887 * the parent's depth already be correct:
888 */
889 int ret = bch2_trans_run(c,
890 for_each_btree_key_reverse_commit(trans, iter,
891 BTREE_ID_snapshots, POS_MAX,
892 BTREE_ITER_prefetch, k,
893 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
894 check_snapshot(trans, &iter, k)));
895 bch_err_fn(c, ret);
896 return ret;
897 }
898
899 static int check_snapshot_exists(struct btree_trans *trans, u32 id)
900 {
901 struct bch_fs *c = trans->c;
902
903 if (bch2_snapshot_equiv(c, id))
904 return 0;
905
906 /* 0 is an invalid tree ID */
907 u32 tree_id = 0;
908 int ret = bch2_snapshot_tree_create(trans, id, 0, &tree_id);
909 if (ret)
910 return ret;
911
912 struct bkey_i_snapshot *snapshot = bch2_trans_kmalloc(trans, sizeof(*snapshot));
913 ret = PTR_ERR_OR_ZERO(snapshot);
914 if (ret)
915 return ret;
916
917 bkey_snapshot_init(&snapshot->k_i);
918 snapshot->k.p = POS(0, id);
919 snapshot->v.tree = cpu_to_le32(tree_id);
920 snapshot->v.btime.lo = cpu_to_le64(bch2_current_time(c));
921
922 return bch2_btree_insert_trans(trans, BTREE_ID_snapshots, &snapshot->k_i, 0) ?:
923 bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
924 bkey_s_c_null, bkey_i_to_s(&snapshot->k_i), 0) ?:
925 bch2_snapshot_set_equiv(trans, bkey_i_to_s_c(&snapshot->k_i));
926 }
927
928 /* Figure out which snapshot nodes belong in the same tree: */
929 struct snapshot_tree_reconstruct {
930 enum btree_id btree;
931 struct bpos cur_pos;
932 snapshot_id_list cur_ids;
933 DARRAY(snapshot_id_list) trees;
934 };
935
936 static void snapshot_tree_reconstruct_exit(struct snapshot_tree_reconstruct *r)
937 {
938 darray_for_each(r->trees, i)
939 darray_exit(i);
940 darray_exit(&r->trees);
941 darray_exit(&r->cur_ids);
942 }
943
944 static inline bool same_snapshot(struct snapshot_tree_reconstruct *r, struct bpos pos)
945 {
946 return r->btree == BTREE_ID_inodes
947 ? r->cur_pos.offset == pos.offset
948 : r->cur_pos.inode == pos.inode;
949 }
950
951 static inline bool snapshot_id_lists_have_common(snapshot_id_list *l, snapshot_id_list *r)
952 {
953 darray_for_each(*l, i)
954 if (snapshot_list_has_id(r, *i))
955 return true;
956 return false;
957 }
958
959 static void snapshot_id_list_to_text(struct printbuf *out, snapshot_id_list *s)
960 {
961 bool first = true;
962 darray_for_each(*s, i) {
963 if (!first)
964 prt_char(out, ' ');
965 first = false;
966 prt_printf(out, "%u", *i);
967 }
968 }
969
970 static int snapshot_tree_reconstruct_next(struct bch_fs *c, struct snapshot_tree_reconstruct *r)
971 {
972 if (r->cur_ids.nr) {
973 darray_for_each(r->trees, i)
974 if (snapshot_id_lists_have_common(i, &r->cur_ids)) {
975 int ret = snapshot_list_merge(c, i, &r->cur_ids);
976 if (ret)
977 return ret;
978 goto out;
979 }
980 darray_push(&r->trees, r->cur_ids);
981 darray_init(&r->cur_ids);
982 }
983 out:
984 r->cur_ids.nr = 0;
985 return 0;
986 }
987
988 static int get_snapshot_trees(struct bch_fs *c, struct snapshot_tree_reconstruct *r, struct bpos pos)
989 {
990 if (!same_snapshot(r, pos))
991 snapshot_tree_reconstruct_next(c, r);
992 r->cur_pos = pos;
993 return snapshot_list_add_nodup(c, &r->cur_ids, pos.snapshot);
994 }
995
996 int bch2_reconstruct_snapshots(struct bch_fs *c)
997 {
998 struct btree_trans *trans = bch2_trans_get(c);
999 struct printbuf buf = PRINTBUF;
1000 struct snapshot_tree_reconstruct r = {};
1001 int ret = 0;
1002
1003 for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {
1004 if (btree_type_has_snapshots(btree)) {
1005 r.btree = btree;
1006
1007 ret = for_each_btree_key(trans, iter, btree, POS_MIN,
1008 BTREE_ITER_all_snapshots|BTREE_ITER_prefetch, k, ({
1009 get_snapshot_trees(c, &r, k.k->p);
1010 }));
1011 if (ret)
1012 goto err;
1013
1014 snapshot_tree_reconstruct_next(c, &r);
1015 }
1016 }
1017
1018 darray_for_each(r.trees, t) {
1019 printbuf_reset(&buf);
1020 snapshot_id_list_to_text(&buf, t);
1021
1022 darray_for_each(*t, id) {
1023 if (fsck_err_on(!bch2_snapshot_equiv(c, *id),
1024 trans, snapshot_node_missing,
1025 "snapshot node %u from tree %s missing, recreate?", *id, buf.buf)) {
1026 if (t->nr > 1) {
1027 bch_err(c, "cannot reconstruct snapshot trees with multiple nodes");
1028 ret = -BCH_ERR_fsck_repair_unimplemented;
1029 goto err;
1030 }
1031
1032 ret = commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
1033 check_snapshot_exists(trans, *id));
1034 if (ret)
1035 goto err;
1036 }
1037 }
1038 }
1039 fsck_err:
1040 err:
1041 bch2_trans_put(trans);
1042 snapshot_tree_reconstruct_exit(&r);
1043 printbuf_exit(&buf);
1044 bch_err_fn(c, ret);
1045 return ret;
1046 }
1047
1048 int bch2_check_key_has_snapshot(struct btree_trans *trans,
1049 struct btree_iter *iter,
1050 struct bkey_s_c k)
1051 {
1052 struct bch_fs *c = trans->c;
1053 struct printbuf buf = PRINTBUF;
1054 int ret = 0;
1055
1056 if (fsck_err_on(!bch2_snapshot_equiv(c, k.k->p.snapshot),
1057 trans, bkey_in_missing_snapshot,
1058 "key in missing snapshot %s, delete?",
1059 (bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
1060 ret = bch2_btree_delete_at(trans, iter,
1061 BTREE_UPDATE_internal_snapshot_node) ?: 1;
1062 fsck_err:
1063 printbuf_exit(&buf);
1064 return ret;
1065 }
1066
1067 /*
1068 * Mark a snapshot as deleted, for future cleanup:
1069 */
1070 int bch2_snapshot_node_set_deleted(struct btree_trans *trans, u32 id)
1071 {
1072 struct btree_iter iter;
1073 struct bkey_i_snapshot *s;
1074 int ret = 0;
1075
1076 s = bch2_bkey_get_mut_typed(trans, &iter,
1077 BTREE_ID_snapshots, POS(0, id),
1078 0, snapshot);
1079 ret = PTR_ERR_OR_ZERO(s);
1080 if (unlikely(ret)) {
1081 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT),
1082 trans->c, "missing snapshot %u", id);
1083 return ret;
1084 }
1085
1086 /* already deleted? */
1087 if (BCH_SNAPSHOT_DELETED(&s->v))
1088 goto err;
1089
1090 SET_BCH_SNAPSHOT_DELETED(&s->v, true);
1091 SET_BCH_SNAPSHOT_SUBVOL(&s->v, false);
1092 s->v.subvol = 0;
1093 err:
1094 bch2_trans_iter_exit(trans, &iter);
1095 return ret;
1096 }
1097
1098 static inline void normalize_snapshot_child_pointers(struct bch_snapshot *s)
1099 {
1100 if (le32_to_cpu(s->children[0]) < le32_to_cpu(s->children[1]))
1101 swap(s->children[0], s->children[1]);
1102 }
1103
1104 static int bch2_snapshot_node_delete(struct btree_trans *trans, u32 id)
1105 {
1106 struct bch_fs *c = trans->c;
1107 struct btree_iter iter, p_iter = (struct btree_iter) { NULL };
1108 struct btree_iter c_iter = (struct btree_iter) { NULL };
1109 struct btree_iter tree_iter = (struct btree_iter) { NULL };
1110 struct bkey_s_c_snapshot s;
1111 u32 parent_id, child_id;
1112 unsigned i;
1113 int ret = 0;
1114
1115 s = bch2_bkey_get_iter_typed(trans, &iter, BTREE_ID_snapshots, POS(0, id),
1116 BTREE_ITER_intent, snapshot);
1117 ret = bkey_err(s);
1118 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
1119 "missing snapshot %u", id);
1120
1121 if (ret)
1122 goto err;
1123
1124 BUG_ON(s.v->children[1]);
1125
1126 parent_id = le32_to_cpu(s.v->parent);
1127 child_id = le32_to_cpu(s.v->children[0]);
1128
1129 if (parent_id) {
1130 struct bkey_i_snapshot *parent;
1131
1132 parent = bch2_bkey_get_mut_typed(trans, &p_iter,
1133 BTREE_ID_snapshots, POS(0, parent_id),
1134 0, snapshot);
1135 ret = PTR_ERR_OR_ZERO(parent);
1136 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
1137 "missing snapshot %u", parent_id);
1138 if (unlikely(ret))
1139 goto err;
1140
1141 /* find entry in parent->children for node being deleted */
1142 for (i = 0; i < 2; i++)
1143 if (le32_to_cpu(parent->v.children[i]) == id)
1144 break;
1145
1146 if (bch2_fs_inconsistent_on(i == 2, c,
1147 "snapshot %u missing child pointer to %u",
1148 parent_id, id))
1149 goto err;
1150
1151 parent->v.children[i] = cpu_to_le32(child_id);
1152
1153 normalize_snapshot_child_pointers(&parent->v);
1154 }
1155
1156 if (child_id) {
1157 struct bkey_i_snapshot *child;
1158
1159 child = bch2_bkey_get_mut_typed(trans, &c_iter,
1160 BTREE_ID_snapshots, POS(0, child_id),
1161 0, snapshot);
1162 ret = PTR_ERR_OR_ZERO(child);
1163 bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
1164 "missing snapshot %u", child_id);
1165 if (unlikely(ret))
1166 goto err;
1167
1168 child->v.parent = cpu_to_le32(parent_id);
1169
1170 if (!child->v.parent) {
1171 child->v.skip[0] = 0;
1172 child->v.skip[1] = 0;
1173 child->v.skip[2] = 0;
1174 }
1175 }
1176
1177 if (!parent_id) {
1178 /*
1179 * We're deleting the root of a snapshot tree: update the
1180 * snapshot_tree entry to point to the new root, or delete it if
1181 * this is the last snapshot ID in this tree:
1182 */
1183 struct bkey_i_snapshot_tree *s_t;
1184
1185 BUG_ON(s.v->children[1]);
1186
1187 s_t = bch2_bkey_get_mut_typed(trans, &tree_iter,
1188 BTREE_ID_snapshot_trees, POS(0, le32_to_cpu(s.v->tree)),
1189 0, snapshot_tree);
1190 ret = PTR_ERR_OR_ZERO(s_t);
1191 if (ret)
1192 goto err;
1193
1194 if (s.v->children[0]) {
1195 s_t->v.root_snapshot = s.v->children[0];
1196 } else {
1197 s_t->k.type = KEY_TYPE_deleted;
1198 set_bkey_val_u64s(&s_t->k, 0);
1199 }
1200 }
1201
1202 ret = bch2_btree_delete_at(trans, &iter, 0);
1203 err:
1204 bch2_trans_iter_exit(trans, &tree_iter);
1205 bch2_trans_iter_exit(trans, &p_iter);
1206 bch2_trans_iter_exit(trans, &c_iter);
1207 bch2_trans_iter_exit(trans, &iter);
1208 return ret;
1209 }
1210
1211 static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,
1212 u32 *new_snapids,
1213 u32 *snapshot_subvols,
1214 unsigned nr_snapids)
1215 {
1216 struct bch_fs *c = trans->c;
1217 struct btree_iter iter;
1218 struct bkey_i_snapshot *n;
1219 struct bkey_s_c k;
1220 unsigned i, j;
1221 u32 depth = bch2_snapshot_depth(c, parent);
1222 int ret;
1223
1224 bch2_trans_iter_init(trans, &iter, BTREE_ID_snapshots,
1225 POS_MIN, BTREE_ITER_intent);
1226 k = bch2_btree_iter_peek(&iter);
1227 ret = bkey_err(k);
1228 if (ret)
1229 goto err;
1230
1231 for (i = 0; i < nr_snapids; i++) {
1232 k = bch2_btree_iter_prev_slot(&iter);
1233 ret = bkey_err(k);
1234 if (ret)
1235 goto err;
1236
1237 if (!k.k || !k.k->p.offset) {
1238 ret = -BCH_ERR_ENOSPC_snapshot_create;
1239 goto err;
1240 }
1241
1242 n = bch2_bkey_alloc(trans, &iter, 0, snapshot);
1243 ret = PTR_ERR_OR_ZERO(n);
1244 if (ret)
1245 goto err;
1246
1247 n->v.flags = 0;
1248 n->v.parent = cpu_to_le32(parent);
1249 n->v.subvol = cpu_to_le32(snapshot_subvols[i]);
1250 n->v.tree = cpu_to_le32(tree);
1251 n->v.depth = cpu_to_le32(depth);
1252 n->v.btime.lo = cpu_to_le64(bch2_current_time(c));
1253 n->v.btime.hi = 0;
1254
1255 for (j = 0; j < ARRAY_SIZE(n->v.skip); j++)
1256 n->v.skip[j] = cpu_to_le32(bch2_snapshot_skiplist_get(c, parent));
1257
1258 bubble_sort(n->v.skip, ARRAY_SIZE(n->v.skip), cmp_le32);
1259 SET_BCH_SNAPSHOT_SUBVOL(&n->v, true);
1260
1261 ret = __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0,
1262 bkey_s_c_null, bkey_i_to_s_c(&n->k_i), 0);
1263 if (ret)
1264 goto err;
1265
1266 new_snapids[i] = iter.pos.offset;
1267
1268 mutex_lock(&c->snapshot_table_lock);
1269 snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i];
1270 mutex_unlock(&c->snapshot_table_lock);
1271 }
1272 err:
1273 bch2_trans_iter_exit(trans, &iter);
1274 return ret;
1275 }
1276
1277 /*
1278 * Create new snapshot IDs as children of an existing snapshot ID:
1279 */
1280 static int bch2_snapshot_node_create_children(struct btree_trans *trans, u32 parent,
1281 u32 *new_snapids,
1282 u32 *snapshot_subvols,
1283 unsigned nr_snapids)
1284 {
1285 struct btree_iter iter;
1286 struct bkey_i_snapshot *n_parent;
1287 int ret = 0;
1288
1289 n_parent = bch2_bkey_get_mut_typed(trans, &iter,
1290 BTREE_ID_snapshots, POS(0, parent),
1291 0, snapshot);
1292 ret = PTR_ERR_OR_ZERO(n_parent);
1293 if (unlikely(ret)) {
1294 if (bch2_err_matches(ret, ENOENT))
1295 bch_err(trans->c, "snapshot %u not found", parent);
1296 return ret;
1297 }
1298
1299 if (n_parent->v.children[0] || n_parent->v.children[1]) {
1300 bch_err(trans->c, "Trying to add child snapshot nodes to parent that already has children");
1301 ret = -EINVAL;
1302 goto err;
1303 }
1304
1305 ret = create_snapids(trans, parent, le32_to_cpu(n_parent->v.tree),
1306 new_snapids, snapshot_subvols, nr_snapids);
1307 if (ret)
1308 goto err;
1309
1310 n_parent->v.children[0] = cpu_to_le32(new_snapids[0]);
1311 n_parent->v.children[1] = cpu_to_le32(new_snapids[1]);
1312 n_parent->v.subvol = 0;
1313 SET_BCH_SNAPSHOT_SUBVOL(&n_parent->v, false);
1314 err:
1315 bch2_trans_iter_exit(trans, &iter);
1316 return ret;
1317 }
1318
1319 /*
1320 * Create a snapshot node that is the root of a new tree:
1321 */
1322 static int bch2_snapshot_node_create_tree(struct btree_trans *trans,
1323 u32 *new_snapids,
1324 u32 *snapshot_subvols,
1325 unsigned nr_snapids)
1326 {
1327 struct bkey_i_snapshot_tree *n_tree;
1328 int ret;
1329
1330 n_tree = __bch2_snapshot_tree_create(trans);
1331 ret = PTR_ERR_OR_ZERO(n_tree) ?:
1332 create_snapids(trans, 0, n_tree->k.p.offset,
1333 new_snapids, snapshot_subvols, nr_snapids);
1334 if (ret)
1335 return ret;
1336
1337 n_tree->v.master_subvol = cpu_to_le32(snapshot_subvols[0]);
1338 n_tree->v.root_snapshot = cpu_to_le32(new_snapids[0]);
1339 return 0;
1340 }
1341
1342 int bch2_snapshot_node_create(struct btree_trans *trans, u32 parent,
1343 u32 *new_snapids,
1344 u32 *snapshot_subvols,
1345 unsigned nr_snapids)
1346 {
1347 BUG_ON((parent == 0) != (nr_snapids == 1));
1348 BUG_ON((parent != 0) != (nr_snapids == 2));
1349
1350 return parent
1351 ? bch2_snapshot_node_create_children(trans, parent,
1352 new_snapids, snapshot_subvols, nr_snapids)
1353 : bch2_snapshot_node_create_tree(trans,
1354 new_snapids, snapshot_subvols, nr_snapids);
1355
1356 }
1357
1358 /*
1359 * If we have an unlinked inode in an internal snapshot node, and the inode
1360 * really has been deleted in all child snapshots, how does this get cleaned up?
1361 *
1362 * first there is the problem of how keys that have been overwritten in all
1363 * child snapshots get deleted (unimplemented?), but inodes may perhaps be
1364 * special?
1365 *
1366 * also: unlinked inode in internal snapshot appears to not be getting deleted
1367 * correctly if inode doesn't exist in leaf snapshots
1368 *
1369 * solution:
1370 *
1371 * for a key in an interior snapshot node that needs work to be done that
1372 * requires it to be mutated: iterate over all descendent leaf nodes and copy
1373 * that key to snapshot leaf nodes, where we can mutate it
1374 */
1375
1376 static int delete_dead_snapshots_process_key(struct btree_trans *trans,
1377 struct btree_iter *iter,
1378 struct bkey_s_c k,
1379 snapshot_id_list *deleted,
1380 snapshot_id_list *equiv_seen,
1381 struct bpos *last_pos)
1382 {
1383 int ret = bch2_check_key_has_snapshot(trans, iter, k);
1384 if (ret)
1385 return ret < 0 ? ret : 0;
1386
1387 struct bch_fs *c = trans->c;
1388 u32 equiv = bch2_snapshot_equiv(c, k.k->p.snapshot);
1389 if (!equiv) /* key for invalid snapshot node, but we chose not to delete */
1390 return 0;
1391
1392 if (!bkey_eq(k.k->p, *last_pos))
1393 equiv_seen->nr = 0;
1394
1395 if (snapshot_list_has_id(deleted, k.k->p.snapshot))
1396 return bch2_btree_delete_at(trans, iter,
1397 BTREE_UPDATE_internal_snapshot_node);
1398
1399 if (!bpos_eq(*last_pos, k.k->p) &&
1400 snapshot_list_has_id(equiv_seen, equiv))
1401 return bch2_btree_delete_at(trans, iter,
1402 BTREE_UPDATE_internal_snapshot_node);
1403
1404 *last_pos = k.k->p;
1405
1406 ret = snapshot_list_add_nodup(c, equiv_seen, equiv);
1407 if (ret)
1408 return ret;
1409
1410 /*
1411 * When we have a linear chain of snapshot nodes, we consider
1412 * those to form an equivalence class: we're going to collapse
1413 * them all down to a single node, and keep the leaf-most node -
1414 * which has the same id as the equivalence class id.
1415 *
1416 * If there are multiple keys in different snapshots at the same
1417 * position, we're only going to keep the one in the newest
1418 * snapshot (we delete the others above) - the rest have been
1419 * overwritten and are redundant, and for the key we're going to keep we
1420 * need to move it to the equivalance class ID if it's not there
1421 * already.
1422 */
1423 if (equiv != k.k->p.snapshot) {
1424 struct bkey_i *new = bch2_bkey_make_mut_noupdate(trans, k);
1425 int ret = PTR_ERR_OR_ZERO(new);
1426 if (ret)
1427 return ret;
1428
1429 new->k.p.snapshot = equiv;
1430
1431 struct btree_iter new_iter;
1432 bch2_trans_iter_init(trans, &new_iter, iter->btree_id, new->k.p,
1433 BTREE_ITER_all_snapshots|
1434 BTREE_ITER_cached|
1435 BTREE_ITER_intent);
1436
1437 ret = bch2_btree_iter_traverse(&new_iter) ?:
1438 bch2_trans_update(trans, &new_iter, new,
1439 BTREE_UPDATE_internal_snapshot_node) ?:
1440 bch2_btree_delete_at(trans, iter,
1441 BTREE_UPDATE_internal_snapshot_node);
1442 bch2_trans_iter_exit(trans, &new_iter);
1443 if (ret)
1444 return ret;
1445 }
1446
1447 return 0;
1448 }
1449
1450 static int bch2_snapshot_needs_delete(struct btree_trans *trans, struct bkey_s_c k)
1451 {
1452 struct bkey_s_c_snapshot snap;
1453 u32 children[2];
1454 int ret;
1455
1456 if (k.k->type != KEY_TYPE_snapshot)
1457 return 0;
1458
1459 snap = bkey_s_c_to_snapshot(k);
1460 if (BCH_SNAPSHOT_DELETED(snap.v) ||
1461 BCH_SNAPSHOT_SUBVOL(snap.v))
1462 return 0;
1463
1464 children[0] = le32_to_cpu(snap.v->children[0]);
1465 children[1] = le32_to_cpu(snap.v->children[1]);
1466
1467 ret = bch2_snapshot_live(trans, children[0]) ?:
1468 bch2_snapshot_live(trans, children[1]);
1469 if (ret < 0)
1470 return ret;
1471 return !ret;
1472 }
1473
1474 /*
1475 * For a given snapshot, if it doesn't have a subvolume that points to it, and
1476 * it doesn't have child snapshot nodes - it's now redundant and we can mark it
1477 * as deleted.
1478 */
1479 static int bch2_delete_redundant_snapshot(struct btree_trans *trans, struct bkey_s_c k)
1480 {
1481 int ret = bch2_snapshot_needs_delete(trans, k);
1482
1483 return ret <= 0
1484 ? ret
1485 : bch2_snapshot_node_set_deleted(trans, k.k->p.offset);
1486 }
1487
1488 static inline u32 bch2_snapshot_nth_parent_skip(struct bch_fs *c, u32 id, u32 n,
1489 snapshot_id_list *skip)
1490 {
1491 rcu_read_lock();
1492 while (snapshot_list_has_id(skip, id))
1493 id = __bch2_snapshot_parent(c, id);
1494
1495 while (n--) {
1496 do {
1497 id = __bch2_snapshot_parent(c, id);
1498 } while (snapshot_list_has_id(skip, id));
1499 }
1500 rcu_read_unlock();
1501
1502 return id;
1503 }
1504
1505 static int bch2_fix_child_of_deleted_snapshot(struct btree_trans *trans,
1506 struct btree_iter *iter, struct bkey_s_c k,
1507 snapshot_id_list *deleted)
1508 {
1509 struct bch_fs *c = trans->c;
1510 u32 nr_deleted_ancestors = 0;
1511 struct bkey_i_snapshot *s;
1512 int ret;
1513
1514 if (k.k->type != KEY_TYPE_snapshot)
1515 return 0;
1516
1517 if (snapshot_list_has_id(deleted, k.k->p.offset))
1518 return 0;
1519
1520 s = bch2_bkey_make_mut_noupdate_typed(trans, k, snapshot);
1521 ret = PTR_ERR_OR_ZERO(s);
1522 if (ret)
1523 return ret;
1524
1525 darray_for_each(*deleted, i)
1526 nr_deleted_ancestors += bch2_snapshot_is_ancestor(c, s->k.p.offset, *i);
1527
1528 if (!nr_deleted_ancestors)
1529 return 0;
1530
1531 le32_add_cpu(&s->v.depth, -nr_deleted_ancestors);
1532
1533 if (!s->v.depth) {
1534 s->v.skip[0] = 0;
1535 s->v.skip[1] = 0;
1536 s->v.skip[2] = 0;
1537 } else {
1538 u32 depth = le32_to_cpu(s->v.depth);
1539 u32 parent = bch2_snapshot_parent(c, s->k.p.offset);
1540
1541 for (unsigned j = 0; j < ARRAY_SIZE(s->v.skip); j++) {
1542 u32 id = le32_to_cpu(s->v.skip[j]);
1543
1544 if (snapshot_list_has_id(deleted, id)) {
1545 id = bch2_snapshot_nth_parent_skip(c,
1546 parent,
1547 depth > 1
1548 ? get_random_u32_below(depth - 1)
1549 : 0,
1550 deleted);
1551 s->v.skip[j] = cpu_to_le32(id);
1552 }
1553 }
1554
1555 bubble_sort(s->v.skip, ARRAY_SIZE(s->v.skip), cmp_le32);
1556 }
1557
1558 return bch2_trans_update(trans, iter, &s->k_i, 0);
1559 }
1560
1561 int bch2_delete_dead_snapshots(struct bch_fs *c)
1562 {
1563 struct btree_trans *trans;
1564 snapshot_id_list deleted = { 0 };
1565 snapshot_id_list deleted_interior = { 0 };
1566 int ret = 0;
1567
1568 if (!test_and_clear_bit(BCH_FS_need_delete_dead_snapshots, &c->flags))
1569 return 0;
1570
1571 trans = bch2_trans_get(c);
1572
1573 /*
1574 * For every snapshot node: If we have no live children and it's not
1575 * pointed to by a subvolume, delete it:
1576 */
1577 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots,
1578 POS_MIN, 0, k,
1579 NULL, NULL, 0,
1580 bch2_delete_redundant_snapshot(trans, k));
1581 bch_err_msg(c, ret, "deleting redundant snapshots");
1582 if (ret)
1583 goto err;
1584
1585 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1586 POS_MIN, 0, k,
1587 bch2_snapshot_set_equiv(trans, k));
1588 bch_err_msg(c, ret, "in bch2_snapshots_set_equiv");
1589 if (ret)
1590 goto err;
1591
1592 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1593 POS_MIN, 0, k, ({
1594 if (k.k->type != KEY_TYPE_snapshot)
1595 continue;
1596
1597 BCH_SNAPSHOT_DELETED(bkey_s_c_to_snapshot(k).v)
1598 ? snapshot_list_add(c, &deleted, k.k->p.offset)
1599 : 0;
1600 }));
1601 bch_err_msg(c, ret, "walking snapshots");
1602 if (ret)
1603 goto err;
1604
1605 for (unsigned btree = 0; btree < BTREE_ID_NR; btree++) {
1606 struct bpos last_pos = POS_MIN;
1607 snapshot_id_list equiv_seen = { 0 };
1608 struct disk_reservation res = { 0 };
1609
1610 if (!btree_type_has_snapshots(btree))
1611 continue;
1612
1613 ret = for_each_btree_key_commit(trans, iter,
1614 btree, POS_MIN,
1615 BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
1616 &res, NULL, BCH_TRANS_COMMIT_no_enospc,
1617 delete_dead_snapshots_process_key(trans, &iter, k, &deleted,
1618 &equiv_seen, &last_pos));
1619
1620 bch2_disk_reservation_put(c, &res);
1621 darray_exit(&equiv_seen);
1622
1623 bch_err_msg(c, ret, "deleting keys from dying snapshots");
1624 if (ret)
1625 goto err;
1626 }
1627
1628 bch2_trans_unlock(trans);
1629 down_write(&c->snapshot_create_lock);
1630
1631 ret = for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1632 POS_MIN, 0, k, ({
1633 u32 snapshot = k.k->p.offset;
1634 u32 equiv = bch2_snapshot_equiv(c, snapshot);
1635
1636 equiv != snapshot
1637 ? snapshot_list_add(c, &deleted_interior, snapshot)
1638 : 0;
1639 }));
1640
1641 bch_err_msg(c, ret, "walking snapshots");
1642 if (ret)
1643 goto err_create_lock;
1644
1645 /*
1646 * Fixing children of deleted snapshots can't be done completely
1647 * atomically, if we crash between here and when we delete the interior
1648 * nodes some depth fields will be off:
1649 */
1650 ret = for_each_btree_key_commit(trans, iter, BTREE_ID_snapshots, POS_MIN,
1651 BTREE_ITER_intent, k,
1652 NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
1653 bch2_fix_child_of_deleted_snapshot(trans, &iter, k, &deleted_interior));
1654 if (ret)
1655 goto err_create_lock;
1656
1657 darray_for_each(deleted, i) {
1658 ret = commit_do(trans, NULL, NULL, 0,
1659 bch2_snapshot_node_delete(trans, *i));
1660 bch_err_msg(c, ret, "deleting snapshot %u", *i);
1661 if (ret)
1662 goto err_create_lock;
1663 }
1664
1665 darray_for_each(deleted_interior, i) {
1666 ret = commit_do(trans, NULL, NULL, 0,
1667 bch2_snapshot_node_delete(trans, *i));
1668 bch_err_msg(c, ret, "deleting snapshot %u", *i);
1669 if (ret)
1670 goto err_create_lock;
1671 }
1672 err_create_lock:
1673 up_write(&c->snapshot_create_lock);
1674 err:
1675 darray_exit(&deleted_interior);
1676 darray_exit(&deleted);
1677 bch2_trans_put(trans);
1678 bch_err_fn(c, ret);
1679 return ret;
1680 }
1681
1682 void bch2_delete_dead_snapshots_work(struct work_struct *work)
1683 {
1684 struct bch_fs *c = container_of(work, struct bch_fs, snapshot_delete_work);
1685
1686 set_worker_desc("bcachefs-delete-dead-snapshots/%s", c->name);
1687
1688 bch2_delete_dead_snapshots(c);
1689 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
1690 }
1691
1692 void bch2_delete_dead_snapshots_async(struct bch_fs *c)
1693 {
1694 if (bch2_write_ref_tryget(c, BCH_WRITE_REF_delete_dead_snapshots) &&
1695 !queue_work(c->write_ref_wq, &c->snapshot_delete_work))
1696 bch2_write_ref_put(c, BCH_WRITE_REF_delete_dead_snapshots);
1697 }
1698
1699 int __bch2_key_has_snapshot_overwrites(struct btree_trans *trans,
1700 enum btree_id id,
1701 struct bpos pos)
1702 {
1703 struct bch_fs *c = trans->c;
1704 struct btree_iter iter;
1705 struct bkey_s_c k;
1706 int ret;
1707
1708 bch2_trans_iter_init(trans, &iter, id, pos,
1709 BTREE_ITER_not_extents|
1710 BTREE_ITER_all_snapshots);
1711 while (1) {
1712 k = bch2_btree_iter_prev(&iter);
1713 ret = bkey_err(k);
1714 if (ret)
1715 break;
1716
1717 if (!k.k)
1718 break;
1719
1720 if (!bkey_eq(pos, k.k->p))
1721 break;
1722
1723 if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, pos.snapshot)) {
1724 ret = 1;
1725 break;
1726 }
1727 }
1728 bch2_trans_iter_exit(trans, &iter);
1729
1730 return ret;
1731 }
1732
1733 static u32 bch2_snapshot_smallest_child(struct bch_fs *c, u32 id)
1734 {
1735 const struct snapshot_t *s = snapshot_t(c, id);
1736
1737 return s->children[1] ?: s->children[0];
1738 }
1739
1740 static u32 bch2_snapshot_smallest_descendent(struct bch_fs *c, u32 id)
1741 {
1742 u32 child;
1743
1744 while ((child = bch2_snapshot_smallest_child(c, id)))
1745 id = child;
1746 return id;
1747 }
1748
1749 static int bch2_propagate_key_to_snapshot_leaf(struct btree_trans *trans,
1750 enum btree_id btree,
1751 struct bkey_s_c interior_k,
1752 u32 leaf_id, struct bpos *new_min_pos)
1753 {
1754 struct btree_iter iter;
1755 struct bpos pos = interior_k.k->p;
1756 struct bkey_s_c k;
1757 struct bkey_i *new;
1758 int ret;
1759
1760 pos.snapshot = leaf_id;
1761
1762 bch2_trans_iter_init(trans, &iter, btree, pos, BTREE_ITER_intent);
1763 k = bch2_btree_iter_peek_slot(&iter);
1764 ret = bkey_err(k);
1765 if (ret)
1766 goto out;
1767
1768 /* key already overwritten in this snapshot? */
1769 if (k.k->p.snapshot != interior_k.k->p.snapshot)
1770 goto out;
1771
1772 if (bpos_eq(*new_min_pos, POS_MIN)) {
1773 *new_min_pos = k.k->p;
1774 new_min_pos->snapshot = leaf_id;
1775 }
1776
1777 new = bch2_bkey_make_mut_noupdate(trans, interior_k);
1778 ret = PTR_ERR_OR_ZERO(new);
1779 if (ret)
1780 goto out;
1781
1782 new->k.p.snapshot = leaf_id;
1783 ret = bch2_trans_update(trans, &iter, new, 0);
1784 out:
1785 bch2_trans_iter_exit(trans, &iter);
1786 return ret;
1787 }
1788
1789 int bch2_propagate_key_to_snapshot_leaves(struct btree_trans *trans,
1790 enum btree_id btree,
1791 struct bkey_s_c k,
1792 struct bpos *new_min_pos)
1793 {
1794 struct bch_fs *c = trans->c;
1795 struct bkey_buf sk;
1796 u32 restart_count = trans->restart_count;
1797 int ret = 0;
1798
1799 bch2_bkey_buf_init(&sk);
1800 bch2_bkey_buf_reassemble(&sk, c, k);
1801 k = bkey_i_to_s_c(sk.k);
1802
1803 *new_min_pos = POS_MIN;
1804
1805 for (u32 id = bch2_snapshot_smallest_descendent(c, k.k->p.snapshot);
1806 id < k.k->p.snapshot;
1807 id++) {
1808 if (!bch2_snapshot_is_ancestor(c, id, k.k->p.snapshot) ||
1809 !bch2_snapshot_is_leaf(c, id))
1810 continue;
1811 again:
1812 ret = btree_trans_too_many_iters(trans) ?:
1813 bch2_propagate_key_to_snapshot_leaf(trans, btree, k, id, new_min_pos) ?:
1814 bch2_trans_commit(trans, NULL, NULL, 0);
1815 if (ret && bch2_err_matches(ret, BCH_ERR_transaction_restart)) {
1816 bch2_trans_begin(trans);
1817 goto again;
1818 }
1819
1820 if (ret)
1821 break;
1822 }
1823
1824 bch2_bkey_buf_exit(&sk, c);
1825
1826 return ret ?: trans_was_restarted(trans, restart_count);
1827 }
1828
1829 static int bch2_check_snapshot_needs_deletion(struct btree_trans *trans, struct bkey_s_c k)
1830 {
1831 struct bch_fs *c = trans->c;
1832 struct bkey_s_c_snapshot snap;
1833 int ret = 0;
1834
1835 if (k.k->type != KEY_TYPE_snapshot)
1836 return 0;
1837
1838 snap = bkey_s_c_to_snapshot(k);
1839 if (BCH_SNAPSHOT_DELETED(snap.v) ||
1840 bch2_snapshot_equiv(c, k.k->p.offset) != k.k->p.offset ||
1841 (ret = bch2_snapshot_needs_delete(trans, k)) > 0) {
1842 set_bit(BCH_FS_need_delete_dead_snapshots, &c->flags);
1843 return 0;
1844 }
1845
1846 return ret;
1847 }
1848
1849 int bch2_snapshots_read(struct bch_fs *c)
1850 {
1851 int ret = bch2_trans_run(c,
1852 for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1853 POS_MIN, 0, k,
1854 __bch2_mark_snapshot(trans, BTREE_ID_snapshots, 0, bkey_s_c_null, k, 0) ?:
1855 bch2_snapshot_set_equiv(trans, k) ?:
1856 bch2_check_snapshot_needs_deletion(trans, k)) ?:
1857 for_each_btree_key(trans, iter, BTREE_ID_snapshots,
1858 POS_MIN, 0, k,
1859 (set_is_ancestor_bitmap(c, k.k->p.offset), 0)));
1860 bch_err_fn(c, ret);
1861
1862 /*
1863 * It's important that we check if we need to reconstruct snapshots
1864 * before going RW, so we mark that pass as required in the superblock -
1865 * otherwise, we could end up deleting keys with missing snapshot nodes
1866 * instead
1867 */
1868 BUG_ON(!test_bit(BCH_FS_new_fs, &c->flags) &&
1869 test_bit(BCH_FS_may_go_rw, &c->flags));
1870
1871 if (bch2_err_matches(ret, EIO) ||
1872 (c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots)))
1873 ret = bch2_run_explicit_recovery_pass_persistent(c, BCH_RECOVERY_PASS_reconstruct_snapshots);
1874
1875 return ret;
1876 }
1877
1878 void bch2_fs_snapshots_exit(struct bch_fs *c)
1879 {
1880 kvfree(rcu_dereference_protected(c->snapshots, true));
1881 }
1882
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