Heinz Graalfs <graalfs@xxxxxxxxxxxxxxxxxx> writes:
> Deleting the disk and partitions in virtblk_remove() via del_gendisk() causes
> never ending waits when trying to synch dirty inode pages.
>
> A dummy virtqueue_notify() in virtblk_remove() is used to detect a host
> notification error, latter occurs when block device was hot-unplugged.
> When the dummy host kick failed blk_cleanup_queue() should be invoked
> prior to del_gendisk().
>
> Signed-off-by: Heinz Graalfs <graalfs@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/block/virtio_blk.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index 6472395..98f081a 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -880,8 +880,14 @@ static void virtblk_remove(struct virtio_device *vdev)
> vblk->config_enable = false;
> mutex_unlock(&vblk->config_lock);
>
> - del_gendisk(vblk->disk);
> - blk_cleanup_queue(vblk->disk->queue);
> + virtqueue_notify(vblk->vq);
> + if (virtqueue_is_broken(vblk->vq)) {
> + blk_cleanup_queue(vblk->disk->queue);
> + del_gendisk(vblk->disk);
> + } else {
> + del_gendisk(vblk->disk);
> + blk_cleanup_queue(vblk->disk->queue);
> + }
This seems horribly wrong. Firstly, it's ugly to have a gratuitous
kick. Secondly, it's racy: what if there's a hot unplug (or other
failure) after your virtqueue_is_broken() test? We should be doing I/O
failures which should be handled by del_gendisk() correctly.
Cheers,
Rusty.
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