Commit 24b45e6c authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

virtio_blk: simplify refcounting 



Implement the ->free_disk method to free the virtio_blk structure only
once the last gendisk reference goes away instead of keeping a local
refcount.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20220215094514.3828912-6-hch@lst.de


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 185ed423

drivers/block/virtio_blk.c

+14 −52
Original line number Diff line number Diff line
@@ -69,13 +69,6 @@ struct virtio_blk { 
	/* Process context for config space updates */

	struct work_struct config_work;



	/*

	 * Tracks references from block_device_operations open/release and

	 * virtio_driver probe/remove so this object can be freed once no

	 * longer in use.

	 */

	refcount_t refs;



	/* What host tells us, plus 2 for header & tailer. */

	unsigned int sg_elems;
@@ -391,43 +384,6 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str) 
	return err;

}



static void virtblk_get(struct virtio_blk *vblk)

{

	refcount_inc(&vblk->refs);

}



static void virtblk_put(struct virtio_blk *vblk)

{

	if (refcount_dec_and_test(&vblk->refs)) {

		ida_simple_remove(&vd_index_ida, vblk->index);

		mutex_destroy(&vblk->vdev_mutex);

		kfree(vblk);

	}

}



static int virtblk_open(struct block_device *bd, fmode_t mode)

{

	struct virtio_blk *vblk = bd->bd_disk->private_data;

	int ret = 0;



	mutex_lock(&vblk->vdev_mutex);



	if (vblk->vdev)

		virtblk_get(vblk);

	else

		ret = -ENXIO;



	mutex_unlock(&vblk->vdev_mutex);

	return ret;

}



static void virtblk_release(struct gendisk *disk, fmode_t mode)

{

	struct virtio_blk *vblk = disk->private_data;



	virtblk_put(vblk);

}



/* We provide getgeo only to please some old bootloader/partitioning tools */

static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)

{
@@ -460,11 +416,19 @@ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo) 
	return ret;

}



static void virtblk_free_disk(struct gendisk *disk)

{

	struct virtio_blk *vblk = disk->private_data;



	ida_simple_remove(&vd_index_ida, vblk->index);

	mutex_destroy(&vblk->vdev_mutex);

	kfree(vblk);

}



static const struct block_device_operations virtblk_fops = {

	.owner  	= THIS_MODULE,

	.open = virtblk_open,

	.release = virtblk_release,

	.getgeo		= virtblk_getgeo,

	.free_disk	= virtblk_free_disk,

};



static int index_to_minor(int index)
@@ -791,8 +755,6 @@ static int virtblk_probe(struct virtio_device *vdev) 
		goto out_free_index;

	}



	/* This reference is dropped in virtblk_remove(). */

	refcount_set(&vblk->refs, 1);

	mutex_init(&vblk->vdev_mutex);



	vblk->vdev = vdev;
@@ -970,7 +932,7 @@ static void virtblk_remove(struct virtio_device *vdev) 
	flush_work(&vblk->config_work);



	del_gendisk(vblk->disk);

	blk_cleanup_disk(vblk->disk);

	blk_cleanup_queue(vblk->disk->queue);

	blk_mq_free_tag_set(&vblk->tag_set);



	mutex_lock(&vblk->vdev_mutex);
@@ -986,7 +948,7 @@ static void virtblk_remove(struct virtio_device *vdev) 


	mutex_unlock(&vblk->vdev_mutex);



	virtblk_put(vblk);

	put_disk(vblk->disk);

}



#ifdef CONFIG_PM_SLEEP