cdrom: factor out a cdrom_read_tocentry helper

Factor out a version of the CDROMREADTOCENTRY ioctl handler that can
be called directly from kernel space.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/cdrom/cdrom.c

@@ -2666,32 +2666,37 @@ static int cdrom_ioctl_read_tochdr(struct cdrom_device_info *cdi,
 	return 0;
 }
 
-static int cdrom_ioctl_read_tocentry(struct cdrom_device_info *cdi,
-		void __user *argp)
+int cdrom_read_tocentry(struct cdrom_device_info *cdi,
+		struct cdrom_tocentry *entry)
 {
-	struct cdrom_tocentry entry;
-	u8 requested_format;
+	u8 requested_format = entry->cdte_format;
 	int ret;
 
-	/* cd_dbg(CD_DO_IOCTL, "entering CDROMREADTOCENTRY\n"); */
-
-	if (copy_from_user(&entry, argp, sizeof(entry)))
-		return -EFAULT;
-
-	requested_format = entry.cdte_format;
 	if (requested_format != CDROM_MSF && requested_format != CDROM_LBA)
 		return -EINVAL;
+
 	/* make interface to low-level uniform */
-	entry.cdte_format = CDROM_MSF;
-	ret = cdi->ops->audio_ioctl(cdi, CDROMREADTOCENTRY, &entry);
-	if (ret)
+	entry->cdte_format = CDROM_MSF;
+	ret = cdi->ops->audio_ioctl(cdi, CDROMREADTOCENTRY, entry);
+	if (!ret)
+		sanitize_format(&entry->cdte_addr, &entry->cdte_format,
+				requested_format);
 	return ret;
-	sanitize_format(&entry.cdte_addr, &entry.cdte_format, requested_format);
+}
+EXPORT_SYMBOL_GPL(cdrom_read_tocentry);
 
-	if (copy_to_user(argp, &entry, sizeof(entry)))
+static int cdrom_ioctl_read_tocentry(struct cdrom_device_info *cdi,
+		void __user *argp)
+{
+	struct cdrom_tocentry entry;
+	int ret;
+
+	if (copy_from_user(&entry, argp, sizeof(entry)))
 		return -EFAULT;
-	/* cd_dbg(CD_DO_IOCTL, "CDROMREADTOCENTRY successful\n"); */
-	return 0;
+	ret = cdrom_read_tocentry(cdi, &entry);
+	if (!ret && copy_to_user(argp, &entry, sizeof(entry)))
+		return -EFAULT;
+	return ret;
 }
 
 static int cdrom_ioctl_play_msf(struct cdrom_device_info *cdi,

include/linux/cdrom.h

@@ -94,6 +94,9 @@ struct cdrom_device_ops {
 			       struct packet_command *);
 };
 
+int cdrom_read_tocentry(struct cdrom_device_info *cdi,
+		struct cdrom_tocentry *entry);
+
 /* the general block_device operations structure: */
 extern int cdrom_open(struct cdrom_device_info *cdi, struct block_device *bdev,
 			fmode_t mode);