ceph: pass cred pointer to ceph_mds_auth_match()

This eliminates a redundant get_current_cred() call, because
ceph_mds_check_access() has already obtained this pointer.

As a side effect, this also fixes a reference leak in
ceph_mds_auth_match(): by omitting the get_current_cred() call, no
additional cred reference is taken.

Cc: stable@vger.kernel.org
Fixes: 596afb0 ("ceph: add ceph_mds_check_access() helper")
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

Author: MaxKellermann

fs/ceph/mds_client.c

@@ -5601,9 +5601,9 @@ void send_flush_mdlog(struct ceph_mds_session *s)
 
 static int ceph_mds_auth_match(struct ceph_mds_client *mdsc,
 			       struct ceph_mds_cap_auth *auth,
+			       const struct cred *cred,
 			       char *tpath)
 {
-	const struct cred *cred = get_current_cred();
 	u32 caller_uid = from_kuid(&init_user_ns, cred->fsuid);
 	u32 caller_gid = from_kgid(&init_user_ns, cred->fsgid);
 	struct ceph_client *cl = mdsc->fsc->client;
@@ -5726,7 +5726,7 @@ int ceph_mds_check_access(struct ceph_mds_client *mdsc, char *tpath, int mask)
 	for (i = 0; i < mdsc->s_cap_auths_num; i++) {
 		struct ceph_mds_cap_auth *s = &mdsc->s_cap_auths[i];
 
-		err = ceph_mds_auth_match(mdsc, s, tpath);
+		err = ceph_mds_auth_match(mdsc, s, cred, tpath);
 		if (err < 0) {
 			return err;
 		} else if (err > 0) {