| From 3c22cae51fbd2e4897b87915e49fd6630ae0ab32 Mon Sep 17 00:00:00 2001 |
| From: Halil Pasic <pasic@linux.ibm.com> |
| Date: Thu, 13 Feb 2020 13:37:27 +0100 |
| Subject: [PATCH] virtio-blk: fix hw_queue stopped on arbitrary error |
| |
| commit f5f6b95c72f7f8bb46eace8c5306c752d0133daa upstream. |
| |
| Since nobody else is going to restart our hw_queue for us, the |
| blk_mq_start_stopped_hw_queues() is in virtblk_done() is not sufficient |
| necessarily sufficient to ensure that the queue will get started again. |
| In case of global resource outage (-ENOMEM because mapping failure, |
| because of swiotlb full) our virtqueue may be empty and we can get |
| stuck with a stopped hw_queue. |
| |
| Let us not stop the queue on arbitrary errors, but only on -EONSPC which |
| indicates a full virtqueue, where the hw_queue is guaranteed to get |
| started by virtblk_done() before when it makes sense to carry on |
| submitting requests. Let us also remove a stale comment. |
| |
| Signed-off-by: Halil Pasic <pasic@linux.ibm.com> |
| Cc: Jens Axboe <axboe@kernel.dk> |
| Fixes: f7728002c1c7 ("virtio_ring: fix return code on DMA mapping fails") |
| Link: https://lore.kernel.org/r/20200213123728.61216-2-pasic@linux.ibm.com |
| Signed-off-by: Michael S. Tsirkin <mst@redhat.com> |
| Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c |
| index 7ffd719d89de..c2ed3e9128e3 100644 |
| --- a/drivers/block/virtio_blk.c |
| +++ b/drivers/block/virtio_blk.c |
| @@ -339,10 +339,12 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, |
| err = virtblk_add_req(vblk->vqs[qid].vq, vbr, vbr->sg, num); |
| if (err) { |
| virtqueue_kick(vblk->vqs[qid].vq); |
| - blk_mq_stop_hw_queue(hctx); |
| + /* Don't stop the queue if -ENOMEM: we may have failed to |
| + * bounce the buffer due to global resource outage. |
| + */ |
| + if (err == -ENOSPC) |
| + blk_mq_stop_hw_queue(hctx); |
| spin_unlock_irqrestore(&vblk->vqs[qid].lock, flags); |
| - /* Out of mem doesn't actually happen, since we fall back |
| - * to direct descriptors */ |
| if (err == -ENOMEM || err == -ENOSPC) |
| return BLK_STS_DEV_RESOURCE; |
| return BLK_STS_IOERR; |
| -- |
| 2.7.4 |
| |
