ceph: don't request vxattrs from MDS

It's uselese because MDS reply does not carry any vxattr.
Signed-off-by: Yan, Zheng <zyan@redhat.com>

fs/ceph/xattr.c

@@ -727,8 +727,10 @@ ssize_t __ceph_getxattr(struct inode *inode, const char *name, void *value,
 
 	/* let's see if a virtual xattr was requested */
 	vxattr = ceph_match_vxattr(inode, name);
-	if (vxattr && !(vxattr->exists_cb && !vxattr->exists_cb(ci))) {
-		err = vxattr->getxattr_cb(ci, value, size);
+	if (vxattr) {
+		err = -ENODATA;
+		if (!(vxattr->exists_cb && !vxattr->exists_cb(ci)))
+			err = vxattr->getxattr_cb(ci, value, size);
 		return err;
 	}