Re: [PATCH 0/3 rfc] Fix nvme-tcp and nvme-rdma controller reset hangs
From: Keith Busch <kbusch@kernel.org>
Date: 2021-03-19 19:08:00
On Fri, Mar 19, 2021 at 06:28:17PM +0100, Christoph Hellwig wrote:
What about something like this?
Yes, this looks good.
quoted hunk ↗ jump to hunk
diff --git a/block/blk-core.c b/block/blk-core.c index fc60ff20849738..4344f3c9058282 100644 --- a/block/blk-core.c +++ b/block/blk-core.c@@ -792,7 +792,7 @@ static inline blk_status_t blk_check_zone_append(struct request_queue *q, return BLK_STS_OK; } -static noinline_for_stack bool submit_bio_checks(struct bio *bio) +noinline_for_stack bool submit_bio_checks(struct bio *bio) { struct block_device *bdev = bio->bi_bdev; struct request_queue *q = bdev->bd_disk->queue;diff --git a/block/blk-mq.c b/block/blk-mq.c index d4d7c1caa43966..4ff85692843b49 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c@@ -2286,6 +2286,43 @@ blk_qc_t blk_mq_submit_bio(struct bio *bio) return BLK_QC_T_NONE; } +/** + * blk_mq_submit_bio_direct - hand a bio directly to the driver for I/O + * @bio: The bio describing the location in memory and on the device. + * + * This function behaves similar to submit_bio_noacct(), but does never waits + * for the queue to be unfreozen, instead it return false and lets the caller + * deal with the fallout. It also does not protect against recursion and thus + * must only be used if the called driver is known to be blk-mq based. + */ +bool blk_mq_submit_bio_direct(struct bio *bio, blk_qc_t *qc) +{ + struct gendisk *disk = bio->bi_bdev->bd_disk; + struct request_queue *q = disk->queue; + + if (WARN_ON_ONCE(!current->bio_list) || + WARN_ON_ONCE(disk->fops->submit_bio)) { + bio_io_error(bio); + goto fail; + } + if (!submit_bio_checks(bio)) + goto fail; + + if (unlikely(blk_queue_enter(q, BLK_MQ_REQ_NOWAIT))) + return false; + if (!blk_crypto_bio_prep(&bio)) + goto fail_queue_exit; + *qc = blk_mq_submit_bio(bio); + return true; + +fail_queue_exit: + blk_queue_exit(disk->queue); +fail: + *qc = BLK_QC_T_NONE; + return true; +} +EXPORT_SYMBOL_GPL(blk_mq_submit_bio_direct); + void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, unsigned int hctx_idx) {diff --git a/block/blk.h b/block/blk.h index 3b53e44b967e4e..c4c66b2a9ffb19 100644 --- a/block/blk.h +++ b/block/blk.h@@ -221,6 +221,7 @@ ssize_t part_timeout_show(struct device *, struct device_attribute *, char *); ssize_t part_timeout_store(struct device *, struct device_attribute *, const char *, size_t); +bool submit_bio_checks(struct bio *bio); void __blk_queue_split(struct bio **bio, unsigned int *nr_segs); int ll_back_merge_fn(struct request *req, struct bio *bio, unsigned int nr_segs);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); + goto retry; + } } else if (nvme_available_path(head)) { dev_warn_ratelimited(dev, "no usable path - requeuing I/O\n");diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 2c473c9b899089..6804f397106ada 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h@@ -615,6 +615,7 @@ static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio, } blk_qc_t blk_mq_submit_bio(struct bio *bio); +bool blk_mq_submit_bio_direct(struct bio *bio, blk_qc_t *qc); void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, struct lock_class_key *key);
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