xfs: disable noattr2/attr2 mount options for CRC enabled filesystems

attr2 format is always enabled for v5 superblock filesystems, so the
mount options to enable or disable it need to be cause mount errors.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_super.c

@@ -1372,6 +1372,17 @@ xfs_finish_flags(
 		}
 	}
 
+	/*
+	 * V5 filesystems always use attr2 format for attributes.
+	 */
+	if (xfs_sb_version_hascrc(&mp->m_sb) &&
+	    (mp->m_flags & XFS_MOUNT_NOATTR2)) {
+		xfs_warn(mp,
+"Cannot mount a V5 filesystem as %s. %s is always enabled for V5 filesystems.",
+			MNTOPT_NOATTR2, MNTOPT_ATTR2);
+		return XFS_ERROR(EINVAL);
+	}
+
 	/*
 	 * mkfs'ed attr2 will turn on attr2 mount unless explicitly
 	 * told by noattr2 to turn it off