On Wed, Feb 02, 2022 at 04:56:56PM +0100, Christoph Hellwig wrote:
> 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: Christoph Hellwig <hch@xxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> drivers/block/virtio_blk.c | 64 +++++++-------------------------------
> 1 file changed, 12 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index c443cd64fc9b4..2d939ac1508c1 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -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,
> + .owner = THIS_MODULE,
> + .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;
> @@ -985,8 +947,6 @@ static void virtblk_remove(struct virtio_device *vdev)
> kfree(vblk->vqs);
>
> mutex_unlock(&vblk->vdev_mutex);
> -
> - virtblk_put(vblk);
> }
>
> #ifdef CONFIG_PM_SLEEP
> --
> 2.30.2
