GFS2: Require user to provide argument for FITRIM

When the fstrim_range argument is not provided by user in FITRIM ioctl
we should just return EFAULT and not promoting bad behaviour by filling
the structure in kernel. Let the user deal with it.
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/rgrp.c

@@ -1270,11 +1270,7 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 	if (!blk_queue_discard(q))
 		return -EOPNOTSUPP;
 
-	if (argp == NULL) {
-		r.start = 0;
-		r.len = ULLONG_MAX;
-		r.minlen = 0;
-	} else if (copy_from_user(&r, argp, sizeof(r)))
+	if (copy_from_user(&r, argp, sizeof(r)))
 		return -EFAULT;
 
 	ret = gfs2_rindex_update(sdp);
@@ -1323,7 +1319,7 @@ int gfs2_fitrim(struct file *filp, void __user *argp)
 
 out:
 	r.len = trimmed << 9;
-	if (argp && copy_to_user(argp, &r, sizeof(r)))
+	if (copy_to_user(argp, &r, sizeof(r)))
 		return -EFAULT;
 
 	return ret;