bcachefs: Fix a cache coherency bug in bch2_subvolume_create()

Subvolume deletion doesn't flush & evict the btree key cache - ideally
it would, but that's tricky, so instead bch2_subvolume_create() needs to
make sure the slot doesn't exist in the key cache to avoid triggering
assertions.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2021-10-18 14:46:57 -04:00 committed by Kent Overstreet
parent 6a0f414e20
commit ca130b9c5e

View File

@ -886,6 +886,7 @@ int bch2_subvolume_create(struct btree_trans *trans, u64 inode,
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;
@ -897,7 +898,13 @@ int bch2_subvolume_create(struct btree_trans *trans, u64 inode,
BTREE_ITER_SLOTS|BTREE_ITER_INTENT, k, ret) {
if (bkey_cmp(k.k->p, SUBVOL_POS_MAX) > 0)
break;
if (bkey_deleted(k.k))
/*
* bch2_subvolume_delete() doesn't flush the btree key cache -
* ideally it would but that's tricky
*/
if (bkey_deleted(k.k) &&
!bch2_btree_key_cache_find(c, BTREE_ID_subvolumes, dst_iter.pos))
goto found_slot;
}
@ -925,7 +932,7 @@ found_slot:
goto err;
if (k.k->type != KEY_TYPE_subvolume) {
bch_err(trans->c, "subvolume %u not found", src_subvolid);
bch_err(c, "subvolume %u not found", src_subvolid);
ret = -ENOENT;
goto err;
}