xfs: byteswap constants instead of variables

Micro-optimize various comparisms by always byteswapping the constant
instead of the variable, which allows to do the swap at compile instead
of runtime.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 95862bb..3ad3ab9 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -2127,7 +2127,7 @@
 	 * Validate the magic number of the agf block.
 	 */
 	agf_ok =
-		be32_to_cpu(agf->agf_magicnum) == XFS_AGF_MAGIC &&
+		agf->agf_magicnum == cpu_to_be32(XFS_AGF_MAGIC) &&
 		XFS_AGF_GOOD_VERSION(be32_to_cpu(agf->agf_versionnum)) &&
 		be32_to_cpu(agf->agf_freeblks) <= be32_to_cpu(agf->agf_length) &&
 		be32_to_cpu(agf->agf_flfirst) < XFS_AGFL_SIZE(mp) &&