blk-mq: support multiple hctx maps
Add support for the tag set carrying multiple queue maps, and
for the driver to inform blk-mq how many it wishes to support
through setting set->nr_maps.
This adds an mq_ops helper for drivers that support more than 1
map, mq_ops->rq_flags_to_type(). The function takes request/bio
flags and CPU, and returns a queue map index for that. We then
use the type information in blk_mq_map_queue() to index the map
set.
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 6c39d54..8994c95 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -85,7 +85,14 @@ enum {
};
struct blk_mq_tag_set {
+ /*
+ * map[] holds ctx -> hctx mappings, one map exists for each type
+ * that the driver wishes to support. There are no restrictions
+ * on maps being of the same size, and it's perfectly legal to
+ * share maps between types.
+ */
struct blk_mq_queue_map map[HCTX_MAX_TYPES];
+ unsigned int nr_maps; /* nr entries in map[] */
const struct blk_mq_ops *ops;
unsigned int nr_hw_queues; /* nr hw queues across maps */
unsigned int queue_depth; /* max hw supported */
@@ -109,6 +116,8 @@ struct blk_mq_queue_data {
typedef blk_status_t (queue_rq_fn)(struct blk_mq_hw_ctx *,
const struct blk_mq_queue_data *);
+/* takes rq->cmd_flags as input, returns a hardware type index */
+typedef int (rq_flags_to_type_fn)(struct request_queue *, unsigned int);
typedef bool (get_budget_fn)(struct blk_mq_hw_ctx *);
typedef void (put_budget_fn)(struct blk_mq_hw_ctx *);
typedef enum blk_eh_timer_return (timeout_fn)(struct request *, bool);
@@ -135,6 +144,11 @@ struct blk_mq_ops {
queue_rq_fn *queue_rq;
/*
+ * Return a queue map type for the given request/bio flags
+ */
+ rq_flags_to_type_fn *rq_flags_to_type;
+
+ /*
* Reserve budget before queue request, once .queue_rq is
* run, it is driver's responsibility to release the
* reserved budget. Also we have to handle failure case