Instead of allocating an array of size nr_cpu_ids for set->tags, allocate
an array of size set->nr_hw_queues. This patch improves behavior that was
introduced by commit 868f2f0b7206 ("blk-mq: dynamic h/w context count").Reallocating tag sets from inside __blk_mq_update_nr_hw_queues() is safe because: - All request queues that share the tag sets are frozen before the tag sets are reallocated. - blk_mq_queue_tag_busy_iter() holds q->q_usage_counter while active and hence is serialized against __blk_mq_update_nr_hw_queues(). Cc: Keith Busch <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Ming Lei <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Johannes Thumshirn <[email protected]> Signed-off-by: Bart Van Assche <[email protected]> --- block/blk-mq.c | 47 ++++++++++++++++++++++++++++++----------------- 1 file changed, 30 insertions(+), 17 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 86f6852130fc..1279db579fa2 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2833,19 +2833,6 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, mutex_unlock(&q->sysfs_lock); } -/* - * Maximum number of hardware queues we support. For single sets, we'll never - * have more than the CPUs (software queues). For multiple sets, the tag_set - * user may have set ->nr_hw_queues larger. - */ -static unsigned int nr_hw_queues(struct blk_mq_tag_set *set) -{ - if (set->nr_maps == 1) - return nr_cpu_ids; - - return max(set->nr_hw_queues, nr_cpu_ids); -} - struct request_queue *blk_mq_init_allocated_queue(struct blk_mq_tag_set *set, struct request_queue *q, bool elevator_init) @@ -3012,6 +2999,29 @@ static int blk_mq_update_queue_map(struct blk_mq_tag_set *set) } } +static int blk_mq_realloc_tag_set_tags(struct blk_mq_tag_set *set, + int cur_nr_hw_queues, int new_nr_hw_queues) +{ + struct blk_mq_tags **new_tags; + + if (cur_nr_hw_queues >= new_nr_hw_queues) + return 0; + + new_tags = kcalloc_node(new_nr_hw_queues, sizeof(struct blk_mq_tags *), + GFP_KERNEL, set->numa_node); + if (!new_tags) + return -ENOMEM; + + if (set->tags) + memcpy(new_tags, set->tags, cur_nr_hw_queues * + sizeof(*set->tags)); + kfree(set->tags); + set->tags = new_tags; + set->nr_hw_queues = new_nr_hw_queues; + + return 0; +} + /* * Alloc a tag set to be associated with one or more request queues. * May fail with EINVAL for various error conditions. May adjust the @@ -3065,9 +3075,7 @@ int blk_mq_alloc_tag_set(struct blk_mq_tag_set *set) if (set->nr_maps == 1 && set->nr_hw_queues > nr_cpu_ids) set->nr_hw_queues = nr_cpu_ids; - set->tags = kcalloc_node(nr_hw_queues(set), sizeof(struct blk_mq_tags *), - GFP_KERNEL, set->numa_node); - if (!set->tags) + if (blk_mq_realloc_tag_set_tags(set, 0, set->nr_hw_queues) < 0) return -ENOMEM; ret = -ENOMEM; @@ -3108,7 +3116,7 @@ void blk_mq_free_tag_set(struct blk_mq_tag_set *set) { int i, j; - for (i = 0; i < nr_hw_queues(set); i++) + for (i = 0; i < set->nr_hw_queues; i++) blk_mq_free_map_and_requests(set, i); for (j = 0; j < set->nr_maps; j++) { @@ -3266,6 +3274,10 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, blk_mq_sysfs_unregister(q); } + if (blk_mq_realloc_tag_set_tags(set, set->nr_hw_queues, nr_hw_queues) < + 0) + goto reregister; + prev_nr_hw_queues = set->nr_hw_queues; set->nr_hw_queues = nr_hw_queues; blk_mq_update_queue_map(set); @@ -3282,6 +3294,7 @@ static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, blk_mq_map_swqueue(q); } +reregister: list_for_each_entry(q, &set->tag_list, tag_set_list) { blk_mq_sysfs_register(q); blk_mq_debugfs_register_hctxs(q); -- 2.23.0.866.gb869b98d4c-goog
