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bcachefs: Make check_key_has_snapshot safer

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Snapshot deletion v2 added sentinal values for deleted snapshots, so
"key for deleted snapshot" - i.e. snapshot deletion missed something -
is safe to repair automatically.

But if we find a key for a missing snapshot we have no idea what
happened, and we shouldn't delete it unless we're very sure that
everything else is consistent.

So hook it up to the new bch2_require_recovery_pass(), we'll now only
delete if snapshots and subvolumes have recenlty been checked.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2025-05-31 13:10:43 -04:00
parent 0942b852d4
commit e49cf9b54b
2 changed files with 37 additions and 22 deletions
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13
fs/bcachefs/data_update.c
View File

@ -822,16 +822,11 @@ int bch2_data_update_init(struct btree_trans *trans,
int ret = 0;
if (k.k->p.snapshot) {
/*
* We'll go ERO if we see a key for a missing snapshot, and if
* we're still in recovery we want to give that a chance to
* repair:
*/
if (unlikely(test_bit(BCH_FS_in_recovery, &c->flags) &&
bch2_snapshot_id_state(c, k.k->p.snapshot) == SNAPSHOT_ID_empty))
return bch_err_throw(c, data_update_done_no_snapshot);
ret = bch2_check_key_has_snapshot(trans, iter, k);
if (bch2_err_matches(ret, BCH_ERR_recovery_will_run)) {
/* Can't repair yet, waiting on other recovery passes */
return bch_err_throw(c, data_update_done_no_snapshot);
}
if (ret < 0)
return ret;
if (ret) /* key was deleted */

46
fs/bcachefs/snapshot.c
View File

@ -1045,19 +1045,39 @@ int __bch2_check_key_has_snapshot(struct btree_trans *trans,
ret = bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node) ?: 1;
/*
* Snapshot missing: we should have caught this with btree_lost_data and
* kicked off reconstruct_snapshots, so if we end up here we have no
* idea what happened:
*/
if (fsck_err_on(state == SNAPSHOT_ID_empty,
trans, bkey_in_missing_snapshot,
"key in missing snapshot %s, delete?",
(bch2_btree_id_to_text(&buf, iter->btree_id),
prt_char(&buf, ' '),
bch2_bkey_val_to_text(&buf, c, k), buf.buf)))
ret = bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node) ?: 1;
if (state == SNAPSHOT_ID_empty) {
/*
* Snapshot missing: we should have caught this with btree_lost_data and
* kicked off reconstruct_snapshots, so if we end up here we have no
* idea what happened.
*
* Do not delete unless we know that subvolumes and snapshots
* are consistent:
*
* XXX:
*
* We could be smarter here, and instead of using the generic
* recovery pass ratelimiting, track if there have been any
* changes to the snapshots or inodes btrees since those passes
* last ran.
*/
ret = bch2_require_recovery_pass(c, &buf, BCH_RECOVERY_PASS_check_snapshots) ?: ret;
ret = bch2_require_recovery_pass(c, &buf, BCH_RECOVERY_PASS_check_subvols) ?: ret;
if (c->sb.btrees_lost_data & BIT_ULL(BTREE_ID_snapshots))
ret = bch2_require_recovery_pass(c, &buf, BCH_RECOVERY_PASS_reconstruct_snapshots) ?: ret;
unsigned repair_flags = FSCK_CAN_IGNORE | (!ret ? FSCK_CAN_FIX : 0);
if (__fsck_err(trans, repair_flags, bkey_in_missing_snapshot,
"key in missing snapshot %s, delete?",
(bch2_btree_id_to_text(&buf, iter->btree_id),
prt_char(&buf, ' '),
bch2_bkey_val_to_text(&buf, c, k), buf.buf))) {
ret = bch2_btree_delete_at(trans, iter,
BTREE_UPDATE_internal_snapshot_node) ?: 1;
}
}
fsck_err:
printbuf_exit(&buf);
return ret;