loop: Remove the unnecessary bdev checks and unused bdev variable

The lo->lo_device can't be null if the lo->lo_backing_file is set.
So let's remove the unnecessary bdev checks and the entire bdev
variable in __loop_clr_fd() since the lo->lo_backing_file is already
checked before.

Signed-off-by: Xie Yongji <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

drivers/block/loop.c

···
 {
 	struct file *filp = NULL;
 	gfp_t gfp = lo->old_gfp_mask;
-	struct block_device *bdev = lo->lo_device;
 	int err = 0;
 	bool partscan = false;
 	int lo_number;
···
 	blk_queue_io_min(lo->lo_queue, 512);
 	invalidate_disk(lo->lo_disk);
 	loop_sysfs_exit(lo);
-	if (bdev) {
-		/* let user-space know about this change */
-		kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
-	}
+	/* let user-space know about this change */
+	kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
 	mapping_set_gfp_mask(filp->f_mapping, gfp);
 	/* This is safe: open() is still holding a reference. */
 	module_put(THIS_MODULE);
 	blk_mq_unfreeze_queue(lo->lo_queue);
 
-	partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
+	partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
 	lo_number = lo->lo_number;
 	disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
 out_unlock: