[PATCH 5.16 019/121] virtio-blk: Remove BUG_ON() in virtio_queue_rq()

Greg Kroah-Hartman
2022-03-14T12:32:32Z

From: Xie Yongji <xieyongji@bytedance.com>

[ Upstream commit e030759a1ddcbf61d42b6e996bfeb675e0032d8b ]

Currently we have a BUG_ON() to make sure the number of sg
list does not exceed queue_max_segments() in virtio_queue_rq().
However, the block layer uses queue_max_discard_segments()
instead of queue_max_segments() to limit the sg list for
discard requests. So the BUG_ON() might be triggered if
virtio-blk device reports a larger value for max discard
segment than queue_max_segments(). To fix it, let's simply
remove the BUG_ON() which has become unnecessary after commit
02746e26c39e("virtio-blk: avoid preallocating big SGL for data").
And the unused vblk->sg_elems can also be removed together.

Fixes: 1f23816b8eb8 ("virtio_blk: add discard and write zeroes support")
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20220304100058.116-2-xieyongji@bytedance.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/virtio_blk.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 87f239eb0a99..b3df5e5452a7 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -76,9 +76,6 @@ struct virtio_blk {
*/
refcount_t refs;

- /* What host tells us, plus 2 for header & tailer. */
- unsigned int sg_elems;
-
/* Ida index - used to track minor number allocations. */
int index;

@@ -322,8 +319,6 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
blk_status_t status;
int err;

- BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
-
status = virtblk_setup_cmd(vblk->vdev, req, vbr);
if (unlikely(status))
return status;
@@ -783,8 +778,6 @@ static int virtblk_probe(struct virtio_device *vdev)
/* Prevent integer overflows and honor max vq size */
sg_elems = min_t(u32, sg_elems, VIRTIO_BLK_MAX_SG_ELEMS - 2);

- /* We need extra sg elements at head and tail. */
- sg_elems += 2;
vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
if (!vblk) {
err = -ENOMEM;
@@ -796,7 +789,6 @@ static int virtblk_probe(struct virtio_device *vdev)
mutex_init(&vblk->vdev_mutex);

vblk->vdev = vdev;
- vblk->sg_elems = sg_elems;

INIT_WORK(&vblk->config_work, virtblk_config_changed_work);

@@ -854,7 +846,7 @@ static int virtblk_probe(struct virtio_device *vdev)
set_disk_ro(vblk->disk, 1);

/* We can handle whatever the host told us to handle. */
- blk_queue_max_segments(q, vblk->sg_elems-2);
+ blk_queue_max_segments(q, sg_elems);

/* No real sector limit. */
blk_queue_max_hw_sectors(q, -1U);
@@ -932,7 +924,7 @@ static int virtblk_probe(struct virtio_device *vdev)
* handled it.
*/
if (!v)
- v = sg_elems - 2;
+ v = sg_elems;
blk_queue_max_discard_segments(q,
min(v, MAX_DISCARD_SEGMENTS));

--
2.34.1