[PATCH 0/3 rfc] Fix nvme-tcp and nvme-rdma controller reset hangs

[Sagi Grimberg]

> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index a1d476e1ac020f..92adebfaf86fd1 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -309,6 +309,7 @@ blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
>   	 */
>   	blk_queue_split(&bio);
>   
> +retry:
>   	srcu_idx = srcu_read_lock(&head->srcu);
>   	ns = nvme_find_path(head);
>   	if (likely(ns)) {
> @@ -316,7 +317,12 @@ blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
>   		bio->bi_opf |= REQ_NVME_MPATH;
>   		trace_block_bio_remap(bio, disk_devt(ns->head->disk),
>   				      bio->bi_iter.bi_sector);
> -		ret = submit_bio_noacct(bio);
> +
> +		if (!blk_mq_submit_bio_direct(bio, &ret)) {
> +			nvme_mpath_clear_current_path(ns);
> +			srcu_read_unlock(&head->srcu, srcu_idx);

Its a bit unusual to see mutation of a data protected by srcu while
under the srcu_read_lock, can that be problematic somehow?