ceph: decoding error in ceph_update_snap_realm should return -EIO

Currently ceph_update_snap_realm returns -EINVAL when it hits a decoding
error, which is the wrong error code. -EINVAL implies that the user gave
us a bogus argument to a syscall or something similar. -EIO is more
descriptive when we hit a decoding error.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/snap.c

@@ -791,7 +791,7 @@ int ceph_update_snap_trace(struct ceph_mds_client *mdsc,
 	return 0;
 
 bad:
-	err = -EINVAL;
+	err = -EIO;
 fail:
 	if (realm && !IS_ERR(realm))
 		ceph_put_snap_realm(mdsc, realm);