xfs: return from xfs_symlink_verify early on V4 filesystems

V4 symlink blocks didn't have headers, so return early if this is a V4
filesystem.

Cc: <stable@vger.kernel.org> # v5.1
Fixes: 39708c2 ("xfs: miscellaneous verifier magic value fixups")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Author: Darrick J. Wong

fs/xfs/libxfs/xfs_symlink_remote.c

@@ -92,8 +92,10 @@ xfs_symlink_verify(
 	struct xfs_mount	*mp = bp->b_mount;
 	struct xfs_dsymlink_hdr	*dsl = bp->b_addr;
 
+	/* no verification of non-crc buffers */
 	if (!xfs_has_crc(mp))
-		return __this_address;
+		return NULL;
+
 	if (!xfs_verify_magic(bp, dsl->sl_magic))
 		return __this_address;
 	if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))