Commit 9b79f86e authored by Jens Axboe's avatar Jens Axboe
Browse files

block: ensure that struct blk_mq_alloc_data is fully initialized 



On x86, rep stos will be emitted to clear the the blk_mq_alloc_data
struct, as not all members are being explicitly initialied. Depending on
the type of CPU, this is a noticeable slowdown compared to just ensuring
that the struct is fully initialized when setup.

For the 4 spots that setup a struct blk_mq_alloc_data on the stack,
ensure all members are being initialized.

Reviewed-by: default avatarChaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e093b784

block/blk-mq.c

+21 −1
Original line number Diff line number Diff line
@@ -584,9 +584,13 @@ static struct request *blk_mq_rq_cache_fill(struct request_queue *q, 
	struct blk_mq_alloc_data data = {

		.q		= q,

		.flags		= flags,

		.shallow_depth	= 0,

		.cmd_flags	= opf,

		.rq_flags	= 0,

		.nr_tags	= plug->nr_ios,

		.cached_rqs	= &plug->cached_rqs,

		.ctx		= NULL,

		.hctx		= NULL

	};

	struct request *rq;
@@ -646,8 +650,13 @@ struct request *blk_mq_alloc_request(struct request_queue *q, blk_opf_t opf, 
		struct blk_mq_alloc_data data = {

			.q		= q,

			.flags		= flags,

			.shallow_depth	= 0,

			.cmd_flags	= opf,

			.rq_flags	= 0,

			.nr_tags	= 1,

			.cached_rqs	= NULL,

			.ctx		= NULL,

			.hctx		= NULL

		};

		int ret;
@@ -675,8 +684,13 @@ struct request *blk_mq_alloc_request_hctx(struct request_queue *q, 
	struct blk_mq_alloc_data data = {

		.q		= q,

		.flags		= flags,

		.shallow_depth	= 0,

		.cmd_flags	= opf,

		.rq_flags	= 0,

		.nr_tags	= 1,

		.cached_rqs	= NULL,

		.ctx		= NULL,

		.hctx		= NULL

	};

	u64 alloc_time_ns = 0;

	struct request *rq;
@@ -2967,8 +2981,14 @@ static struct request *blk_mq_get_new_requests(struct request_queue *q, 
{

	struct blk_mq_alloc_data data = {

		.q		= q,

		.nr_tags	= 1,

		.flags		= 0,

		.shallow_depth	= 0,

		.cmd_flags	= bio->bi_opf,

		.rq_flags	= 0,

		.nr_tags	= 1,

		.cached_rqs	= NULL,

		.ctx		= NULL,

		.hctx		= NULL

	};

	struct request *rq;