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_bmap.c b/fs/xfs/xfs_bmap.c
index 7b46b78..2ce6aa6 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -4083,7 +4083,7 @@
 {
 	struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
 
-	if (be32_to_cpu(block->bb_magic) != XFS_BMAP_MAGIC ||
+	if (block->bb_magic != cpu_to_be32(XFS_BMAP_MAGIC) ||
 	    be16_to_cpu(block->bb_level) != level ||
 	    be16_to_cpu(block->bb_numrecs) == 0 ||
 	    be16_to_cpu(block->bb_numrecs) > mp->m_bmap_dmxr[level != 0])