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, this patch
checks the max discard segment for the discard request
in the BUG_ON() instead.
Fixes: 1f23816b8eb8 ("virtio_blk: add discard and write zeroes support")
Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
---
drivers/block/virtio_blk.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index c443cd64fc9b..a1f9045f848e 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -79,6 +79,9 @@ struct virtio_blk {
/* What host tells us, plus 2 for header & tailer. */
unsigned int sg_elems;
+ /* The max discard segment. */
+ unsigned int discard_sg_elems;
+
/* Ida index - used to track minor number allocations. */
int index;
@@ -321,8 +324,10 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
bool notify = false;
blk_status_t status;
int err;
+ u32 sg_elems = (req_op(req) == REQ_OP_DISCARD) ?
+ vblk->discard_sg_elems + 2 : vblk->sg_elems;
- BUG_ON(req->nr_phys_segments + 2 > vblk->sg_elems);
+ BUG_ON(req->nr_phys_segments + 2 > sg_elems);
status = virtblk_setup_cmd(vblk->vdev, req, vbr);
if (unlikely(status))
@@ -925,9 +930,8 @@ static int virtblk_probe(struct virtio_device *vdev)
virtio_cread(vdev, struct virtio_blk_config, max_discard_seg,
&v);
- blk_queue_max_discard_segments(q,
- min_not_zero(v,
- MAX_DISCARD_SEGMENTS));
+ vblk->discard_sg_elems = min_not_zero(v, MAX_DISCARD_SEGMENTS);
+ blk_queue_max_discard_segments(q, vblk->discard_sg_elems);
blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
}
--
2.20.1
