This is a note to let you know that I've just added the patch titled virtio_blk: fix the discard_granularity and discard_alignment queue limits to the 5.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: virtio_blk-fix-the-discard_granularity-and-discard_a.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 8b1ad4df0116ffda5acfce49b20bf97806ee9582 Author: Christoph Hellwig <hch@xxxxxx> Date: Mon Apr 18 06:53:07 2022 +0200 virtio_blk: fix the discard_granularity and discard_alignment queue limits [ Upstream commit 62952cc5bccd89b76d710de1d0b43244af0f2903 ] The discard_alignment queue limit is named a bit misleading means the offset into the block device at which the discard granularity starts. On the other hand the discard_sector_alignment from the virtio 1.1 looks similar to what Linux uses as discard granularity (even if not very well described): "discard_sector_alignment can be used by OS when splitting a request based on alignment. " And at least qemu does set it to the discard granularity. So stop setting the discard_alignment and use the virtio discard_sector_alignment to set the discard granularity. Fixes: 1f23816b8eb8 ("virtio_blk: add discard and write zeroes support") Signed-off-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Link: https://lore.kernel.org/r/20220418045314.360785-5-hch@xxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index c0b8a26892a5..c05138a28475 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -855,11 +855,12 @@ 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; + if (v) + q->limits.discard_granularity = v << SECTOR_SHIFT; + else + q->limits.discard_granularity = blk_size; virtio_cread(vdev, struct virtio_blk_config, max_discard_sectors, &v);