scsi: sg: Consolidate compat ioctl handling

Merge the native and compat ioctl handlers into a single one using
in_compat_syscall().

Link: https://lore.kernel.org/r/20210724072033.1284840-6-hch@lst.deSigned-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sg.c

@@ -1166,28 +1166,11 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
 	if (ret != -ENOIOCTLCMD)
 		return ret;
 
+	if (in_compat_syscall())
+		return scsi_compat_ioctl(sdp->device, cmd_in, p);
 	return scsi_ioctl(sdp->device, cmd_in, p);
 }
 
-#ifdef CONFIG_COMPAT
-static long sg_compat_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
-{
-	void __user *p = compat_ptr(arg);
-	Sg_device *sdp;
-	Sg_fd *sfp;
-	int ret;
-
-	if ((!(sfp = (Sg_fd *) filp->private_data)) || (!(sdp = sfp->parentdp)))
-		return -ENXIO;
-
-	ret = sg_ioctl_common(filp, sdp, sfp, cmd_in, p);
-	if (ret != -ENOIOCTLCMD)
-		return ret;
-
-	return scsi_compat_ioctl(sdp->device, cmd_in, p);
-}
-#endif
-
 static __poll_t
 sg_poll(struct file *filp, poll_table * wait)
 {
@@ -1441,9 +1424,7 @@ static const struct file_operations sg_fops = {
 	.write = sg_write,
 	.poll = sg_poll,
 	.unlocked_ioctl = sg_ioctl,
-#ifdef CONFIG_COMPAT
-	.compat_ioctl = sg_compat_ioctl,
-#endif
+	.compat_ioctl = compat_ptr_ioctl,
 	.open = sg_open,
 	.mmap = sg_mmap,
 	.release = sg_release,