xfs: get rid of open-coded S_ISREG(), etc.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index a97644a..2380a4b 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -263,7 +263,7 @@
 	struct inode		i_vnode;	/* embedded VFS inode */
 } xfs_inode_t;
 
-#define XFS_ISIZE(ip)	(((ip)->i_d.di_mode & S_IFMT) == S_IFREG) ? \
+#define XFS_ISIZE(ip)	S_ISREG((ip)->i_d.di_mode) ? \
 				(ip)->i_size : (ip)->i_d.di_size;
 
 /* Convert from vfs inode to xfs inode */