libxfs: readahead of dir3 data blocks should use the read verifier

commit 2f123bce upstream.

In the dir3 data block readahead function, use the regular read
verifier to check the block's CRC and spot-check the block contents
instead of directly calling only the spot-checking routine.  This
prevents corrupted directory data blocks from being read into the
kernel, which can lead to garbage ls output and directory loops (if
say one of the entries contains slashes and other junk).
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
[ luis: backported to 3.16:
  - file rename: fs/xfs/libxfs/xfs_dir2_data.c -> fs/xfs/xfs_dir2_data.c
  - adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

fs/xfs/xfs_dir2_data.c

@@ -253,7 +253,8 @@ xfs_dir3_data_reada_verify(
 		return;
 	case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
 	case cpu_to_be32(XFS_DIR3_DATA_MAGIC):
-		xfs_dir3_data_verify(bp);
+		bp->b_ops = &xfs_dir3_data_buf_ops;
+		bp->b_ops->verify_read(bp);
 		return;
 	default:
 		xfs_buf_ioerror(bp, EFSCORRUPTED);