sr: use bdev_check_media_change

Switch to use bdev_check_media_change instead of check_disk_change and
call sr_block_revalidate_disk manually.  Also add an explicit call to
sr_block_revalidate_disk just before disk_add() to ensure we always
read check for a ready unit and read the TOC and then stop wiring up
->revalidate_disk.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/scsi/sr.c

@@ -86,6 +86,7 @@ static int sr_remove(struct device *);
 static blk_status_t sr_init_command(struct scsi_cmnd *SCpnt);
 static int sr_done(struct scsi_cmnd *);
 static int sr_runtime_suspend(struct device *dev);
+static int sr_block_revalidate_disk(struct gendisk *disk);
 
 static const struct dev_pm_ops sr_pm_ops = {
 	.runtime_suspend	= sr_runtime_suspend,
@@ -529,7 +530,8 @@ static int sr_block_open(struct block_device *bdev, fmode_t mode)
 
 	sdev = cd->device;
 	scsi_autopm_get_device(sdev);
-	check_disk_change(bdev);
+	if (bdev_check_media_change(bdev))
+		sr_block_revalidate_disk(bdev->bd_disk);
 
 	mutex_lock(&cd->lock);
 	ret = cdrom_open(&cd->cdi, bdev, mode);
@@ -688,7 +690,6 @@ static const struct block_device_operations sr_bdops =
 	.compat_ioctl	= sr_block_compat_ioctl,
 #endif
 	.check_events	= sr_block_check_events,
-	.revalidate_disk = sr_block_revalidate_disk,
 };
 
 static int sr_open(struct cdrom_device_info *cdi, int purpose)
@@ -802,6 +803,7 @@ static int sr_probe(struct device *dev)
 
 	dev_set_drvdata(dev, cd);
 	disk->flags |= GENHD_FL_REMOVABLE;
+	sr_block_revalidate_disk(disk);
 	device_add_disk(&sdev->sdev_gendev, disk, NULL);
 
 	sdev_printk(KERN_DEBUG, sdev,