bcachefs: In fsck, pass BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE when deleting dirents

A user reported an error where we hit an assertion due to deleting a key
in an internal snapshot node, when deleting a dirent that points to a
nonexisting inode.

We try to avoid doing updates to keys for internal snapshot nodes, but
upon inspection of the places where we remove dirents in fsck it appears
BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE is correct for all of them: either
the target dirent doesn't exist, or it's a directory with multiple
dirents pointing to it.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/fsck.c

@@ -311,7 +311,8 @@ static int __remove_dirent(struct btree_trans *trans, struct bpos pos)
 	bch2_trans_iter_init(trans, &iter, BTREE_ID_dirents, pos, BTREE_ITER_INTENT);
 
 	ret = bch2_hash_delete_at(trans, bch2_dirent_hash_desc,
-				  &dir_hash_info, &iter, 0);
+				  &dir_hash_info, &iter,
+				  BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE);
 	bch2_trans_iter_exit(trans, &iter);
 err:
 	if (ret && ret != -EINTR)