btrfs: remove checks for arg argument in btrfs_ioctl_balance

With the removal of balance v1 ioctl the 'arg' argument is guaranteed to
be present so simply remove all conditional code which checks for its
presence.
Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -4346,10 +4346,6 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 	bool need_unlock; /* for mut. excl. ops lock */
 	int ret;
 
-	if (!arg)
-		btrfs_warn(fs_info,
-	"IOC_BALANCE ioctl (v1) is deprecated and will be removed in kernel 5.18");
-
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
@@ -4405,7 +4401,6 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 
 locked:
 
-	if (arg) {
 	bargs = memdup_user(arg, sizeof(*bargs));
 	if (IS_ERR(bargs)) {
 		ret = PTR_ERR(bargs);
@@ -4426,9 +4421,6 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 
 		goto do_balance;
 	}
-	} else {
-		bargs = NULL;
-	}
 
 	if (fs_info->balance_ctl) {
 		ret = -EINPROGRESS;
@@ -4441,16 +4433,11 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 		goto out_bargs;
 	}
 
-	if (arg) {
 	memcpy(&bctl->data, &bargs->data, sizeof(bctl->data));
 	memcpy(&bctl->meta, &bargs->meta, sizeof(bctl->meta));
 	memcpy(&bctl->sys, &bargs->sys, sizeof(bctl->sys));
 
 	bctl->flags = bargs->flags;
-	} else {
-		/* balance everything - no filters */
-		bctl->flags |= BTRFS_BALANCE_TYPE_MASK;
-	}
 
 	if (bctl->flags & ~(BTRFS_BALANCE_ARGS_MASK | BTRFS_BALANCE_TYPE_MASK)) {
 		ret = -EINVAL;
@@ -4469,7 +4456,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg)
 	ret = btrfs_balance(fs_info, bctl, bargs);
 	bctl = NULL;
 
-	if ((ret == 0 || ret == -ECANCELED) && arg) {
+	if (ret == 0 || ret == -ECANCELED) {
 		if (copy_to_user(arg, bargs, sizeof(*bargs)))
 			ret = -EFAULT;
 	}