[PATCH 04/11] virtio_blk: fix the discard_granularity and discard_alignment queue limits
- To: Jens Axboe <axboe@kernel.dk>
- Cc: Richard Weinberger <richard@nod.at>, Johannes Berg <johannes@sipsolutions.net>, Josef Bacik <josef@toxicpanda.com>, "Md. Haris Iqbal" <haris.iqbal@ionos.com>, Jack Wang <jinpu.wang@ionos.com>, "Michael S. Tsirkin" <mst@redhat.com>, Jason Wang <jasowang@redhat.com>, Roger Pau Monné <roger.pau@citrix.com>, Mike Snitzer <snitzer@kernel.org>, Song Liu <song@kernel.org>, Stefan Haberland <sth@linux.ibm.com>, Jan Hoeppner <hoeppner@linux.ibm.com>, "Martin K. Petersen" <martin.petersen@oracle.com>, linux-um@lists.infradead.org, linux-block@vger.kernel.org, nbd@other.debian.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-raid@vger.kernel.org, linux-nvme@lists.infradead.org, linux-s390@vger.kernel.org, dm-devel@redhat.com
- Subject: [PATCH 04/11] virtio_blk: fix the discard_granularity and discard_alignment queue limits
- From: Christoph Hellwig <hch@lst.de>
- Date: Mon, 18 Apr 2022 06:53:07 +0200
- Message-id: <[🔎] 20220418045314.360785-5-hch@lst.de>
- In-reply-to: <[🔎] 20220418045314.360785-1-hch@lst.de>
- References: <[🔎] 20220418045314.360785-1-hch@lst.de>
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@lst.de>
---
drivers/block/virtio_blk.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 6ccf15253dee1..d624cc8eddc3c 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -867,11 +867,12 @@ 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);
--
2.30.2
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