bcachefs: Repair subvol dirents that point to non subvols

when repair switches d_type to or from DT_SUBVOL, we need to update the
target accordingly
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fsck.c

@@ -1678,6 +1678,12 @@ static int check_dirent_target(struct btree_trans *trans,
 
 		bkey_reassemble(&n->k_i, d.s_c);
 		n->v.d_type = inode_d_type(target);
+		if (n->v.d_type == DT_SUBVOL) {
+			n->v.d_parent_subvol = cpu_to_le32(target->bi_parent_subvol);
+			n->v.d_child_subvol = cpu_to_le32(target->bi_subvol);
+		} else {
+			n->v.d_inum = cpu_to_le64(target->bi_inum);
+		}
 
 		ret = bch2_trans_update(trans, iter, &n->k_i, 0);
 		if (ret)