AFS: clean up explicit check for mandatory locks

The __mandatory_lock(inode) macro makes the same check, but makes the code
more readable.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/afs/flock.c

@@ -524,8 +524,7 @@ int afs_lock(struct file *file, int cmd, struct file_lock *fl)
 	       (long long) fl->fl_start, (long long) fl->fl_end);
 
 	/* AFS doesn't support mandatory locks */
-	if ((vnode->vfs_inode.i_mode & (S_ISGID | S_IXGRP)) == S_ISGID &&
-	    fl->fl_type != F_UNLCK)
+	if (__mandatory_lock(&vnode->vfs_inode) && fl->fl_type != F_UNLCK)
 		return -ENOLCK;
 
 	if (IS_GETLK(cmd))