@@ -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);
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 <keith.busch@intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Ming Lei <ming.lei@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Bart Van Assche <bvanassche@acm.org> --- block/blk-mq.c | 47 ++++++++++++++++++++++++++++++----------------- 1 file changed, 30 insertions(+), 17 deletions(-)