summaryrefslogtreecommitdiff
path: root/fs/bcachefs/subvolume.c
blob: 132213761ef6436c04ee96020d2fe297a6eb130c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"
#include "btree_key_cache.h"
#include "btree_update.h"
#include "errcode.h"
#include "error.h"
#include "fs.h"
#include "snapshot.h"
#include "subvolume.h"

#include <linux/random.h>

static int bch2_subvolume_delete(struct btree_trans *, u32);

static struct bpos subvolume_children_pos(struct bkey_s_c k)
{
	if (k.k->type != KEY_TYPE_subvolume)
		return POS_MIN;

	struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);
	if (!s.v->fs_path_parent)
		return POS_MIN;
	return POS(le32_to_cpu(s.v->fs_path_parent), s.k->p.offset);
}

static int check_subvol(struct btree_trans *trans,
			struct btree_iter *iter,
			struct bkey_s_c k)
{
	struct bch_fs *c = trans->c;
	struct bkey_s_c_subvolume subvol;
	struct btree_iter subvol_children_iter = {};
	struct bch_snapshot snapshot;
	struct printbuf buf = PRINTBUF;
	unsigned snapid;
	int ret = 0;

	if (k.k->type != KEY_TYPE_subvolume)
		return 0;

	subvol = bkey_s_c_to_subvolume(k);
	snapid = le32_to_cpu(subvol.v->snapshot);
	ret = bch2_snapshot_lookup(trans, snapid, &snapshot);

	if (bch2_err_matches(ret, ENOENT))
		bch_err(c, "subvolume %llu points to nonexistent snapshot %u",
			k.k->p.offset, snapid);
	if (ret)
		return ret;

	if (BCH_SUBVOLUME_UNLINKED(subvol.v)) {
		ret = bch2_subvolume_delete(trans, iter->pos.offset);
		bch_err_msg(c, ret, "deleting subvolume %llu", iter->pos.offset);
		return ret ?: -BCH_ERR_transaction_restart_nested;
	}

	if (fsck_err_on(subvol.k->p.offset == BCACHEFS_ROOT_SUBVOL &&
			subvol.v->fs_path_parent,
			c, subvol_root_fs_path_parent_nonzero,
			"root subvolume has nonzero fs_path_parent\n%s",
			(bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
		struct bkey_i_subvolume *n =
			bch2_bkey_make_mut_typed(trans, iter, &subvol.s_c, 0, subvolume);
		ret = PTR_ERR_OR_ZERO(n);
		if (ret)
			goto err;

		n->v.fs_path_parent = 0;
	}

	if (subvol.v->fs_path_parent) {
		struct bpos pos = subvolume_children_pos(k);

		struct bkey_s_c subvol_children_k =
			bch2_bkey_get_iter(trans, &subvol_children_iter,
					   BTREE_ID_subvolume_children, pos, 0);
		ret = bkey_err(subvol_children_k);
		if (ret)
			goto err;

		if (fsck_err_on(subvol_children_k.k->type != KEY_TYPE_set,
				c, subvol_children_not_set,
				"subvolume not set in subvolume_children btree at %llu:%llu\n%s",
				pos.inode, pos.offset,
				(printbuf_reset(&buf),
				 bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
			ret = bch2_btree_bit_mod(trans, BTREE_ID_subvolume_children, pos, true);
			if (ret)
				goto err;
		}
	}

	struct bch_inode_unpacked inode;
	struct btree_iter inode_iter = {};
	ret = bch2_inode_peek_nowarn(trans, &inode_iter, &inode,
				    (subvol_inum) { k.k->p.offset, le64_to_cpu(subvol.v->inode) },
				    0);
	bch2_trans_iter_exit(trans, &inode_iter);

	if (ret && !bch2_err_matches(ret, ENOENT))
		return ret;

	if (fsck_err_on(ret, c, subvol_to_missing_root,
			"subvolume %llu points to missing subvolume root %llu:%u",
			k.k->p.offset, le64_to_cpu(subvol.v->inode),
			le32_to_cpu(subvol.v->snapshot))) {
		ret = bch2_subvolume_delete(trans, iter->pos.offset);
		bch_err_msg(c, ret, "deleting subvolume %llu", iter->pos.offset);
		return ret ?: -BCH_ERR_transaction_restart_nested;
	}

	if (fsck_err_on(inode.bi_subvol != subvol.k->p.offset,
			c, subvol_root_wrong_bi_subvol,
			"subvol root %llu:%u has wrong bi_subvol field: got %u, should be %llu",
			inode.bi_inum, inode_iter.k.p.snapshot,
			inode.bi_subvol, subvol.k->p.offset)) {
		inode.bi_subvol = subvol.k->p.offset;
		ret = __bch2_fsck_write_inode(trans, &inode, le32_to_cpu(subvol.v->snapshot));
		if (ret)
			goto err;
	}

	if (!BCH_SUBVOLUME_SNAP(subvol.v)) {
		u32 snapshot_root = bch2_snapshot_root(c, le32_to_cpu(subvol.v->snapshot));
		u32 snapshot_tree;
		struct bch_snapshot_tree st;

		rcu_read_lock();
		snapshot_tree = snapshot_t(c, snapshot_root)->tree;
		rcu_read_unlock();

		ret = bch2_snapshot_tree_lookup(trans, snapshot_tree, &st);

		bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
				"%s: snapshot tree %u not found", __func__, snapshot_tree);

		if (ret)
			return ret;

		if (fsck_err_on(le32_to_cpu(st.master_subvol) != subvol.k->p.offset,
				c, subvol_not_master_and_not_snapshot,
				"subvolume %llu is not set as snapshot but is not master subvolume",
				k.k->p.offset)) {
			struct bkey_i_subvolume *s =
				bch2_bkey_make_mut_typed(trans, iter, &subvol.s_c, 0, subvolume);
			ret = PTR_ERR_OR_ZERO(s);
			if (ret)
				return ret;

			SET_BCH_SUBVOLUME_SNAP(&s->v, true);
		}
	}
err:
fsck_err:
	bch2_trans_iter_exit(trans, &subvol_children_iter);
	printbuf_exit(&buf);
	return ret;
}

int bch2_check_subvols(struct bch_fs *c)
{
	int ret = bch2_trans_run(c,
		for_each_btree_key_commit(trans, iter,
				BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_prefetch, k,
				NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
			check_subvol(trans, &iter, k)));
	bch_err_fn(c, ret);
	return ret;
}

static int check_subvol_child(struct btree_trans *trans,
			      struct btree_iter *child_iter,
			      struct bkey_s_c child_k)
{
	struct bch_fs *c = trans->c;
	struct bch_subvolume s;
	int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_subvolumes, POS(0, child_k.k->p.offset),
					  0, subvolume, &s);
	if (ret && !bch2_err_matches(ret, ENOENT))
		return ret;

	if (fsck_err_on(ret ||
			le32_to_cpu(s.fs_path_parent) != child_k.k->p.inode,
			c, subvol_children_bad,
			"incorrect entry in subvolume_children btree %llu:%llu",
			child_k.k->p.inode, child_k.k->p.offset)) {
		ret = bch2_btree_delete_at(trans, child_iter, 0);
		if (ret)
			goto err;
	}
err:
fsck_err:
	return ret;
}

int bch2_check_subvol_children(struct bch_fs *c)
{
	int ret = bch2_trans_run(c,
		for_each_btree_key_commit(trans, iter,
				BTREE_ID_subvolume_children, POS_MIN, BTREE_ITER_prefetch, k,
				NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
			check_subvol_child(trans, &iter, k)));
	bch_err_fn(c, ret);
	return 0;
}

/* Subvolumes: */

int bch2_subvolume_invalid(struct bch_fs *c, struct bkey_s_c k,
			   enum bch_validate_flags flags, struct printbuf *err)
{
	int ret = 0;

	bkey_fsck_err_on(bkey_lt(k.k->p, SUBVOL_POS_MIN) ||
			 bkey_gt(k.k->p, SUBVOL_POS_MAX), c, err,
			 subvol_pos_bad,
			 "invalid pos");
fsck_err:
	return ret;
}

void bch2_subvolume_to_text(struct printbuf *out, struct bch_fs *c,
			    struct bkey_s_c k)
{
	struct bkey_s_c_subvolume s = bkey_s_c_to_subvolume(k);

	prt_printf(out, "root %llu snapshot id %u",
		   le64_to_cpu(s.v->inode),
		   le32_to_cpu(s.v->snapshot));

	if (bkey_val_bytes(s.k) > offsetof(struct bch_subvolume, creation_parent)) {
		prt_printf(out, " creation_parent %u", le32_to_cpu(s.v->creation_parent));
		prt_printf(out, " fs_parent %u", le32_to_cpu(s.v->fs_path_parent));
	}
}

static int subvolume_children_mod(struct btree_trans *trans, struct bpos pos, bool set)
{
	return !bpos_eq(pos, POS_MIN)
		? bch2_btree_bit_mod(trans, BTREE_ID_subvolume_children, pos, set)
		: 0;
}

int bch2_subvolume_trigger(struct btree_trans *trans,
			   enum btree_id btree_id, unsigned level,
			   struct bkey_s_c old, struct bkey_s new,
			   enum btree_iter_update_trigger_flags flags)
{
	if (flags & BTREE_TRIGGER_transactional) {
		struct bpos children_pos_old = subvolume_children_pos(old);
		struct bpos children_pos_new = subvolume_children_pos(new.s_c);

		if (!bpos_eq(children_pos_old, children_pos_new)) {
			int ret = subvolume_children_mod(trans, children_pos_old, false) ?:
				  subvolume_children_mod(trans, children_pos_new, true);
			if (ret)
				return ret;
		}
	}

	return 0;
}

int bch2_subvol_has_children(struct btree_trans *trans, u32 subvol)
{
	struct btree_iter iter;

	bch2_trans_iter_init(trans, &iter, BTREE_ID_subvolume_children, POS(subvol, 0), 0);
	struct bkey_s_c k = bch2_btree_iter_peek(&iter);
	bch2_trans_iter_exit(trans, &iter);

	return bkey_err(k) ?: k.k && k.k->p.inode == subvol
		? -BCH_ERR_ENOTEMPTY_subvol_not_empty
		: 0;
}

static __always_inline int
bch2_subvolume_get_inlined(struct btree_trans *trans, unsigned subvol,
			   bool inconsistent_if_not_found,
			   int iter_flags,
			   struct bch_subvolume *s)
{
	int ret = bch2_bkey_get_val_typed(trans, BTREE_ID_subvolumes, POS(0, subvol),
					  iter_flags, subvolume, s);
	bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT) &&
				inconsistent_if_not_found,
				trans->c, "missing subvolume %u", subvol);
	return ret;
}

int bch2_subvolume_get(struct btree_trans *trans, unsigned subvol,
		       bool inconsistent_if_not_found,
		       int iter_flags,
		       struct bch_subvolume *s)
{
	return bch2_subvolume_get_inlined(trans, subvol, inconsistent_if_not_found, iter_flags, s);
}

int bch2_subvol_is_ro_trans(struct btree_trans *trans, u32 subvol)
{
	struct bch_subvolume s;
	int ret = bch2_subvolume_get_inlined(trans, subvol, true, 0, &s);
	if (ret)
		return ret;

	if (BCH_SUBVOLUME_RO(&s))
		return -EROFS;
	return 0;
}

int bch2_subvol_is_ro(struct bch_fs *c, u32 subvol)
{
	return bch2_trans_do(c, NULL, NULL, 0,
		bch2_subvol_is_ro_trans(trans, subvol));
}

int bch2_snapshot_get_subvol(struct btree_trans *trans, u32 snapshot,
			     struct bch_subvolume *subvol)
{
	struct bch_snapshot snap;

	return  bch2_snapshot_lookup(trans, snapshot, &snap) ?:
		bch2_subvolume_get(trans, le32_to_cpu(snap.subvol), true, 0, subvol);
}

int bch2_subvolume_get_snapshot(struct btree_trans *trans, u32 subvolid,
				u32 *snapid)
{
	struct btree_iter iter;
	struct bkey_s_c_subvolume subvol;
	int ret;

	subvol = bch2_bkey_get_iter_typed(trans, &iter,
					  BTREE_ID_subvolumes, POS(0, subvolid),
					  BTREE_ITER_cached|BTREE_ITER_with_updates,
					  subvolume);
	ret = bkey_err(subvol);
	bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
				"missing subvolume %u", subvolid);

	if (likely(!ret))
		*snapid = le32_to_cpu(subvol.v->snapshot);
	bch2_trans_iter_exit(trans, &iter);
	return ret;
}

static int bch2_subvolume_reparent(struct btree_trans *trans,
				   struct btree_iter *iter,
				   struct bkey_s_c k,
				   u32 old_parent, u32 new_parent)
{
	struct bkey_i_subvolume *s;
	int ret;

	if (k.k->type != KEY_TYPE_subvolume)
		return 0;

	if (bkey_val_bytes(k.k) > offsetof(struct bch_subvolume, creation_parent) &&
	    le32_to_cpu(bkey_s_c_to_subvolume(k).v->creation_parent) != old_parent)
		return 0;

	s = bch2_bkey_make_mut_typed(trans, iter, &k, 0, subvolume);
	ret = PTR_ERR_OR_ZERO(s);
	if (ret)
		return ret;

	s->v.creation_parent = cpu_to_le32(new_parent);
	return 0;
}

/*
 * Separate from the snapshot tree in the snapshots btree, we record the tree
 * structure of how snapshot subvolumes were created - the parent subvolume of
 * each snapshot subvolume.
 *
 * When a subvolume is deleted, we scan for child subvolumes and reparant them,
 * to avoid dangling references:
 */
static int bch2_subvolumes_reparent(struct btree_trans *trans, u32 subvolid_to_delete)
{
	struct bch_subvolume s;

	return lockrestart_do(trans,
			bch2_subvolume_get(trans, subvolid_to_delete, true,
				   BTREE_ITER_cached, &s)) ?:
		for_each_btree_key_commit(trans, iter,
				BTREE_ID_subvolumes, POS_MIN, BTREE_ITER_prefetch, k,
				NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
			bch2_subvolume_reparent(trans, &iter, k,
					subvolid_to_delete, le32_to_cpu(s.creation_parent)));
}

/*
 * Delete subvolume, mark snapshot ID as deleted, queue up snapshot
 * deletion/cleanup:
 */
static int __bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
{
	struct btree_iter iter;
	struct bkey_s_c_subvolume subvol;
	u32 snapid;
	int ret = 0;

	subvol = bch2_bkey_get_iter_typed(trans, &iter,
				BTREE_ID_subvolumes, POS(0, subvolid),
				BTREE_ITER_cached|BTREE_ITER_intent,
				subvolume);
	ret = bkey_err(subvol);
	bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
				"missing subvolume %u", subvolid);
	if (ret)
		return ret;

	snapid = le32_to_cpu(subvol.v->snapshot);

	ret =   bch2_btree_delete_at(trans, &iter, 0) ?:
		bch2_snapshot_node_set_deleted(trans, snapid);
	bch2_trans_iter_exit(trans, &iter);
	return ret;
}

static int bch2_subvolume_delete(struct btree_trans *trans, u32 subvolid)
{
	return bch2_subvolumes_reparent(trans, subvolid) ?:
		commit_do(trans, NULL, NULL, BCH_TRANS_COMMIT_no_enospc,
			  __bch2_subvolume_delete(trans, subvolid));
}

static void bch2_subvolume_wait_for_pagecache_and_delete(struct work_struct *work)
{
	struct bch_fs *c = container_of(work, struct bch_fs,
				snapshot_wait_for_pagecache_and_delete_work);
	snapshot_id_list s;
	u32 *id;
	int ret = 0;

	while (!ret) {
		mutex_lock(&c->snapshots_unlinked_lock);
		s = c->snapshots_unlinked;
		darray_init(&c->snapshots_unlinked);
		mutex_unlock(&c->snapshots_unlinked_lock);

		if (!s.nr)
			break;

		bch2_evict_subvolume_inodes(c, &s);

		for (id = s.data; id < s.data + s.nr; id++) {
			ret = bch2_trans_run(c, bch2_subvolume_delete(trans, *id));
			bch_err_msg(c, ret, "deleting subvolume %u", *id);
			if (ret)
				break;
		}

		darray_exit(&s);
	}

	bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
}

struct subvolume_unlink_hook {
	struct btree_trans_commit_hook	h;
	u32				subvol;
};

static int bch2_subvolume_wait_for_pagecache_and_delete_hook(struct btree_trans *trans,
						      struct btree_trans_commit_hook *_h)
{
	struct subvolume_unlink_hook *h = container_of(_h, struct subvolume_unlink_hook, h);
	struct bch_fs *c = trans->c;
	int ret = 0;

	mutex_lock(&c->snapshots_unlinked_lock);
	if (!snapshot_list_has_id(&c->snapshots_unlinked, h->subvol))
		ret = snapshot_list_add(c, &c->snapshots_unlinked, h->subvol);
	mutex_unlock(&c->snapshots_unlinked_lock);

	if (ret)
		return ret;

	if (!bch2_write_ref_tryget(c, BCH_WRITE_REF_snapshot_delete_pagecache))
		return -EROFS;

	if (!queue_work(c->write_ref_wq, &c->snapshot_wait_for_pagecache_and_delete_work))
		bch2_write_ref_put(c, BCH_WRITE_REF_snapshot_delete_pagecache);
	return 0;
}

int bch2_subvolume_unlink(struct btree_trans *trans, u32 subvolid)
{
	struct btree_iter iter;
	struct bkey_i_subvolume *n;
	struct subvolume_unlink_hook *h;
	int ret = 0;

	h = bch2_trans_kmalloc(trans, sizeof(*h));
	ret = PTR_ERR_OR_ZERO(h);
	if (ret)
		return ret;

	h->h.fn		= bch2_subvolume_wait_for_pagecache_and_delete_hook;
	h->subvol	= subvolid;
	bch2_trans_commit_hook(trans, &h->h);

	n = bch2_bkey_get_mut_typed(trans, &iter,
			BTREE_ID_subvolumes, POS(0, subvolid),
			BTREE_ITER_cached, subvolume);
	ret = PTR_ERR_OR_ZERO(n);
	if (unlikely(ret)) {
		bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), trans->c,
					"missing subvolume %u", subvolid);
		return ret;
	}

	SET_BCH_SUBVOLUME_UNLINKED(&n->v, true);
	bch2_trans_iter_exit(trans, &iter);
	return ret;
}

int bch2_subvolume_create(struct btree_trans *trans, u64 inode,
			  u32 parent_subvolid,
			  u32 src_subvolid,
			  u32 *new_subvolid,
			  u32 *new_snapshotid,
			  bool ro)
{
	struct bch_fs *c = trans->c;
	struct btree_iter dst_iter, src_iter = (struct btree_iter) { NULL };
	struct bkey_i_subvolume *new_subvol = NULL;
	struct bkey_i_subvolume *src_subvol = NULL;
	u32 parent = 0, new_nodes[2], snapshot_subvols[2];
	int ret = 0;

	ret = bch2_bkey_get_empty_slot(trans, &dst_iter,
				BTREE_ID_subvolumes, POS(0, U32_MAX));
	if (ret == -BCH_ERR_ENOSPC_btree_slot)
		ret = -BCH_ERR_ENOSPC_subvolume_create;
	if (ret)
		return ret;

	snapshot_subvols[0] = dst_iter.pos.offset;
	snapshot_subvols[1] = src_subvolid;

	if (src_subvolid) {
		/* Creating a snapshot: */

		src_subvol = bch2_bkey_get_mut_typed(trans, &src_iter,
				BTREE_ID_subvolumes, POS(0, src_subvolid),
				BTREE_ITER_cached, subvolume);
		ret = PTR_ERR_OR_ZERO(src_subvol);
		if (unlikely(ret)) {
			bch2_fs_inconsistent_on(bch2_err_matches(ret, ENOENT), c,
						"subvolume %u not found", src_subvolid);
			goto err;
		}

		parent = le32_to_cpu(src_subvol->v.snapshot);
	}

	ret = bch2_snapshot_node_create(trans, parent, new_nodes,
					snapshot_subvols,
					src_subvolid ? 2 : 1);
	if (ret)
		goto err;

	if (src_subvolid) {
		src_subvol->v.snapshot = cpu_to_le32(new_nodes[1]);
		ret = bch2_trans_update(trans, &src_iter, &src_subvol->k_i, 0);
		if (ret)
			goto err;
	}

	new_subvol = bch2_bkey_alloc(trans, &dst_iter, 0, subvolume);
	ret = PTR_ERR_OR_ZERO(new_subvol);
	if (ret)
		goto err;

	new_subvol->v.flags		= 0;
	new_subvol->v.snapshot		= cpu_to_le32(new_nodes[0]);
	new_subvol->v.inode		= cpu_to_le64(inode);
	new_subvol->v.creation_parent	= cpu_to_le32(src_subvolid);
	new_subvol->v.fs_path_parent	= cpu_to_le32(parent_subvolid);
	new_subvol->v.otime.lo		= cpu_to_le64(bch2_current_time(c));
	new_subvol->v.otime.hi		= 0;

	SET_BCH_SUBVOLUME_RO(&new_subvol->v, ro);
	SET_BCH_SUBVOLUME_SNAP(&new_subvol->v, src_subvolid != 0);

	*new_subvolid	= new_subvol->k.p.offset;
	*new_snapshotid	= new_nodes[0];
err:
	bch2_trans_iter_exit(trans, &src_iter);
	bch2_trans_iter_exit(trans, &dst_iter);
	return ret;
}

int bch2_initialize_subvolumes(struct bch_fs *c)
{
	struct bkey_i_snapshot_tree	root_tree;
	struct bkey_i_snapshot		root_snapshot;
	struct bkey_i_subvolume		root_volume;
	int ret;

	bkey_snapshot_tree_init(&root_tree.k_i);
	root_tree.k.p.offset		= 1;
	root_tree.v.master_subvol	= cpu_to_le32(1);
	root_tree.v.root_snapshot	= cpu_to_le32(U32_MAX);

	bkey_snapshot_init(&root_snapshot.k_i);
	root_snapshot.k.p.offset = U32_MAX;
	root_snapshot.v.flags	= 0;
	root_snapshot.v.parent	= 0;
	root_snapshot.v.subvol	= cpu_to_le32(BCACHEFS_ROOT_SUBVOL);
	root_snapshot.v.tree	= cpu_to_le32(1);
	SET_BCH_SNAPSHOT_SUBVOL(&root_snapshot.v, true);

	bkey_subvolume_init(&root_volume.k_i);
	root_volume.k.p.offset = BCACHEFS_ROOT_SUBVOL;
	root_volume.v.flags	= 0;
	root_volume.v.snapshot	= cpu_to_le32(U32_MAX);
	root_volume.v.inode	= cpu_to_le64(BCACHEFS_ROOT_INO);

	ret =   bch2_btree_insert(c, BTREE_ID_snapshot_trees,	&root_tree.k_i, NULL, 0) ?:
		bch2_btree_insert(c, BTREE_ID_snapshots,	&root_snapshot.k_i, NULL, 0) ?:
		bch2_btree_insert(c, BTREE_ID_subvolumes,	&root_volume.k_i, NULL, 0);
	bch_err_fn(c, ret);
	return ret;
}

static int __bch2_fs_upgrade_for_subvolumes(struct btree_trans *trans)
{
	struct btree_iter iter;
	struct bkey_s_c k;
	struct bch_inode_unpacked inode;
	int ret;

	k = bch2_bkey_get_iter(trans, &iter, BTREE_ID_inodes,
			       SPOS(0, BCACHEFS_ROOT_INO, U32_MAX), 0);
	ret = bkey_err(k);
	if (ret)
		return ret;

	if (!bkey_is_inode(k.k)) {
		bch_err(trans->c, "root inode not found");
		ret = -BCH_ERR_ENOENT_inode;
		goto err;
	}

	ret = bch2_inode_unpack(k, &inode);
	BUG_ON(ret);

	inode.bi_subvol = BCACHEFS_ROOT_SUBVOL;

	ret = bch2_inode_write(trans, &iter, &inode);
err:
	bch2_trans_iter_exit(trans, &iter);
	return ret;
}

/* set bi_subvol on root inode */
int bch2_fs_upgrade_for_subvolumes(struct bch_fs *c)
{
	int ret = bch2_trans_do(c, NULL, NULL, BCH_TRANS_COMMIT_lazy_rw,
				__bch2_fs_upgrade_for_subvolumes(trans));
	bch_err_fn(c, ret);
	return ret;
}

int bch2_fs_subvolumes_init(struct bch_fs *c)
{
	INIT_WORK(&c->snapshot_delete_work, bch2_delete_dead_snapshots_work);
	INIT_WORK(&c->snapshot_wait_for_pagecache_and_delete_work,
		  bch2_subvolume_wait_for_pagecache_and_delete);
	mutex_init(&c->snapshots_unlinked_lock);
	return 0;
}