unimore/kernel-hacking-2024-linux-steffo
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bcachefs: Make sure to initialize equiv when creating new snapshots

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Previously, equiv was set in the snapshot deletion path, which is where
it's needed - equiv, for snapshot ID equivalence classes, would ideally
be a private data structure to the snapshot deletion path.

But if a new snapshot is created while snapshot deletion is running,
move_key_to_correct_snapshot() moves a key to snapshot id 0 - oops.

Fixes: https://github.com/koverstreet/bcachefs/issues/593
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2023-09-23 16:55:03 -04:00
parent 82142a5541
commit eebe8a8459
2 changed files with 6 additions and 4 deletions
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8
fs/bcachefs/snapshot.c
View file

@ -343,7 +343,7 @@ int bch2_snapshot_lookup(struct btree_trans *trans, u32 id,
BTREE_ITER_WITH_UPDATES, snapshot, s);
}
int bch2_snapshot_live(struct btree_trans *trans, u32 id)
static int bch2_snapshot_live(struct btree_trans *trans, u32 id)
{
struct bch_snapshot v;
int ret;
@ -370,7 +370,7 @@ int bch2_snapshot_live(struct btree_trans *trans, u32 id)
* it's part of such a linear chain: this correctly sets equivalence classes on
* startup if we run leaf to root (i.e. in natural key order).
*/
int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
static int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k)
{
struct bch_fs *c = trans->c;
unsigned i, nr_live = 0, live_idx = 0;
@ -1071,6 +1071,10 @@ static int create_snapids(struct btree_trans *trans, u32 parent, u32 tree,
goto err;
new_snapids[i] = iter.pos.offset;
mutex_lock(&c->snapshot_table_lock);
snapshot_t_mut(c, new_snapids[i])->equiv = new_snapids[i];
mutex_unlock(&c->snapshot_table_lock);
}
err:
bch2_trans_iter_exit(trans, &iter);

2
fs/bcachefs/snapshot.h
View file

@ -235,8 +235,6 @@ int bch2_snapshot_lookup(struct btree_trans *trans, u32 id,
struct bch_snapshot *s);
int bch2_snapshot_get_subvol(struct btree_trans *, u32,
struct bch_subvolume *);
int bch2_snapshot_live(struct btree_trans *trans, u32 id);
int bch2_snapshot_set_equiv(struct btree_trans *trans, struct bkey_s_c k);
/* only exported for tests: */
int bch2_snapshot_node_create(struct btree_trans *, u32,