On Thu, Feb 24, 2022 at 06:38:02PM +0900, Akihiko Odaki
wrote:> Virtual I/O Device (VIRTIO) Version 1.1
>
https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.html
> > discard_sector_alignment can be used by OS when splitting a request
> > based on alignment.
>
> According to Documentation/ABI/stable/sysfs-block, the corresponding
> field in the kernel is, confusingly, discard_granularity, not
> discard_alignment.
Good catch, struct virtio_blk_config->discard_sector_alignment is Linux
q->limits.discard_granularity.
>
> Signed-off-by: Akihiko Odaki <akihiko.odaki at gmail.com>
> ---
> drivers/block/virtio_blk.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> index c443cd64fc9b..1fb3c89900e3 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -913,11 +913,9 @@ static int virtblk_probe(struct virtio_device *vdev)
> blk_queue_io_opt(q, blk_size * opt_io_size);
>
> if (virtio_has_feature(vdev, VIRTIO_BLK_F_DISCARD)) {
> - q->limits.discard_granularity = blk_size;
> -
> virtio_cread(vdev, struct virtio_blk_config,
> discard_sector_alignment, &v);
> - q->limits.discard_alignment = v ? v << SECTOR_SHIFT : 0;
Should we use struct virtio_blk_config->topology.alignment_offset
("offset of first aligned logical block" and used for Linux
blk_queue_alignment_offset()) for q->limits.discard_alignment?
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