block: add a cdrom_device_info pointer to struct gendisk

Add a pointer to the CDROM information structure to struct gendisk.
This will allow various removable media file systems to call directly
into the CDROM layer instead of abusing ioctls with kernel pointers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/paride/pcd.c

@@ -1032,7 +1032,7 @@ static int __init pcd_init(void)
 
 	for (unit = 0, cd = pcd; unit < PCD_UNITS; unit++, cd++) {
 		if (cd->present) {
-			register_cdrom(&cd->info);
+			register_cdrom(cd->disk, &cd->info);
 			cd->disk->private_data = cd;
 			add_disk(cd->disk);
 		}

drivers/cdrom/cdrom.c

@@ -586,7 +586,7 @@ static int cdrom_mrw_set_lba_space(struct cdrom_device_info *cdi, int space)
 	return 0;
 }
 
-int register_cdrom(struct cdrom_device_info *cdi)
+int register_cdrom(struct gendisk *disk, struct cdrom_device_info *cdi)
 {
 	static char banner_printed;
 	const struct cdrom_device_ops *cdo = cdi->ops;
@@ -601,6 +601,9 @@ int register_cdrom(struct cdrom_device_info *cdi)
 		cdrom_sysctl_register();
 	}
 
+	cdi->disk = disk;
+	disk->cdi = cdi;
+
 	ENSURE(cdo, drive_status, CDC_DRIVE_STATUS);
 	if (cdo->check_events == NULL && cdo->media_changed == NULL)
 		WARN_ON_ONCE(cdo->capability & (CDC_MEDIA_CHANGED | CDC_SELECT_DISC));

drivers/cdrom/gdrom.c

@@ -770,7 +770,7 @@ static int probe_gdrom(struct platform_device *devptr)
 		goto probe_fail_no_disk;
 	}
 	probe_gdrom_setupdisk();
-	if (register_cdrom(gd.cd_info)) {
+	if (register_cdrom(gd.disk, gd.cd_info)) {
 		err = -ENODEV;
 		goto probe_fail_cdrom_register;
 	}

drivers/ide/ide-cd.c

@@ -1305,8 +1305,7 @@ static int ide_cdrom_register(ide_drive_t *drive, int nslots)
 	if (drive->atapi_flags & IDE_AFLAG_NO_SPEED_SELECT)
 		devinfo->mask |= CDC_SELECT_SPEED;
 
-	devinfo->disk = info->disk;
-	return register_cdrom(devinfo);
+	return register_cdrom(info->disk, devinfo);
 }
 
 static int ide_cdrom_probe_capabilities(ide_drive_t *drive)

drivers/scsi/sr.c

@@ -794,9 +794,8 @@ static int sr_probe(struct device *dev)
 	set_capacity(disk, cd->capacity);
 	disk->private_data = &cd->driver;
 	disk->queue = sdev->request_queue;
-	cd->cdi.disk = disk;
 
-	if (register_cdrom(&cd->cdi))
+	if (register_cdrom(disk, &cd->cdi))
 		goto fail_put;
 
 	/*

include/linux/cdrom.h

@@ -104,7 +104,7 @@ extern unsigned int cdrom_check_events(struct cdrom_device_info *cdi,
 				       unsigned int clearing);
 extern int cdrom_media_changed(struct cdrom_device_info *);
 
-extern int register_cdrom(struct cdrom_device_info *cdi);
+extern int register_cdrom(struct gendisk *disk, struct cdrom_device_info *cdi);
 extern void unregister_cdrom(struct cdrom_device_info *cdi);
 
 typedef struct {

include/linux/genhd.h

@@ -217,11 +217,20 @@ struct gendisk {
 #ifdef  CONFIG_BLK_DEV_INTEGRITY
 	struct kobject integrity_kobj;
 #endif	/* CONFIG_BLK_DEV_INTEGRITY */
+#if IS_ENABLED(CONFIG_CDROM)
+	struct cdrom_device_info *cdi;
+#endif
 	int node_id;
 	struct badblocks *bb;
 	struct lockdep_map lockdep_map;
 };
 
+#if IS_REACHABLE(CONFIG_CDROM)
+#define disk_to_cdi(disk)	((disk)->cdi)
+#else
+#define disk_to_cdi(disk)	NULL
+#endif
+
 static inline struct gendisk *part_to_disk(struct hd_struct *part)
 {
 	if (likely(part)) {