blk-mq: streamline handling of q->mq_ops->queue_rq result (7bf13729) · Commits · 戴 / test

Current handling of q->mq_ops->queue_rq result is a bit ugly: - two branches which needs to 'continue' have to check if the dispatch local list is empty, otherwise one bad request may be retrieved via 'rq = list_first_entry(list, struct request, queuelist);' - the branch of 'if (unlikely(ret != BLK_STS_OK))' isn't easy to follow, since it is actually one error branch. Streamline this handling, so the code becomes more readable, meantime potential kernel oops can be avoided in case that the last request in local dispatch list is failed. Fixes: ("blk-mq: switch ->queue_rq return value to blk_status_t") Signed-off-by:

Ming Lei <ming.lei@redhat.com> Reviewed-by:

Johannes Thumshirn <johannes.thumshirn@wdc.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by:

Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

+11 −13

Original line number	Diff line number	Diff line
		@@ -1387,30 +1387,28 @@ bool blk_mq_dispatch_rq_list(struct blk_mq_hw_ctx hctx, struct list_head list,
		if (nr_budgets)
		nr_budgets--;
		ret = q->mq_ops->queue_rq(hctx, &bd);
		if (ret == BLK_STS_RESOURCE \|\| ret == BLK_STS_DEV_RESOURCE) {
		blk_mq_handle_dev_resource(rq, list);
		switch (ret) {
		case BLK_STS_OK:
		queued++;
		break;
		} else if (ret == BLK_STS_ZONE_RESOURCE) {
		case BLK_STS_RESOURCE:
		case BLK_STS_DEV_RESOURCE:
		blk_mq_handle_dev_resource(rq, list);
		goto out;
		case BLK_STS_ZONE_RESOURCE:
		/*
		* Move the request to zone_list and keep going through
		* the dispatch list to find more requests the drive can
		* accept.
		*/
		blk_mq_handle_zone_resource(rq, &zone_list);
		if (list_empty(list))
		break;
		continue;
		}

		if (unlikely(ret != BLK_STS_OK)) {
		default:
		errors++;
		blk_mq_end_request(rq, BLK_STS_IOERR);
		continue;
		}

		queued++;
		} while (!list_empty(list));

		out:
		if (!list_empty(&zone_list))
		list_splice_tail_init(&zone_list, list);

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