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blk-mq: remap queues when adding/removing hardware queues

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blk_mq_update_nr_hw_queues() used to remap hardware queues, which is the
behavior that drivers expect. However, commit 4e68a011428a 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: 4e68a011428a ("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>
This commit is contained in:
Omar Sandoval 2017-04-07 08:53:11 -06:00 committed by Jens Axboe
parent 54d5329d42
commit ebe8bddb6e
1 changed files with 10 additions and 4 deletions
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14
block/blk-mq.c
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@ -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);