blk-mq: remap queues when adding/removing hardware queues (ebe8bddb) · Commits · e / devices / android_kernel_fairphone_FP4

blk_mq_update_nr_hw_queues() used to remap hardware queues, which is the behavior that drivers expect. However, commit changed blk_mq_queue_reinit() to not remap queues for the case of CPU hotplugging, inadvertently making blk_mq_update_nr_hw_queues() not remap queues as well. This breaks, for example, NBD's multi-connection mode, leaving the added hardware queues unused. Fix it by making blk_mq_update_nr_hw_queues() explicitly remap the queues. Fixes: ("blk-mq: don't redistribute hardware queues on a CPU hotplug event") Reviewed-by:

Keith Busch <keith.busch@intel.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Reviewed-by:

Sagi Grimberg <sagi@grimberg.me> Signed-off-by:

Omar Sandoval <osandov@fb.com> Signed-off-by:

Jens Axboe <axboe@fb.com>

block/blk-mq.c

+10 −4

Original line number	Diff line number	Diff line
		@@ -2570,6 +2570,14 @@ static int blk_mq_alloc_rq_maps(struct blk_mq_tag_set *set)
		return 0;
		}

		static int blk_mq_update_queue_map(struct blk_mq_tag_set *set)
		{
		if (set->ops->map_queues)
		return set->ops->map_queues(set);
		else
		return blk_mq_map_queues(set);
		}

		/*
		* Alloc a tag set to be associated with one or more request queues.
		* May fail with EINVAL for various error conditions. May adjust the
		@@ -2624,10 +2632,7 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set)
		if (!set->mq_map)
		goto out_free_tags;

		if (set->ops->map_queues)
		ret = set->ops->map_queues(set);
		else
		ret = blk_mq_map_queues(set);
		ret = blk_mq_update_queue_map(set);
		if (ret)
		goto out_free_mq_map;

		@@ -2719,6 +2724,7 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues)
		blk_mq_freeze_queue(q);

		set->nr_hw_queues = nr_hw_queues;
		blk_mq_update_queue_map(set);
		list_for_each_entry(q, &set->tag_list, tag_set_list) {
		blk_mq_realloc_hw_ctxs(set, q);