Commit f5d632d1 authored by Jens Axboe's avatar Jens Axboe
Browse files

block: shrink rq_map_data a bit 



We don't need full ints for several of these members. Change the
page_order and nr_entries to unsigned shorts, and the true/false from_user
and null_mapped to booleans.

This shrinks the struct from 32 to 24 bytes on 64-bit archs.

Reviewed-by: default avatarChaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent d322f355

block/blk-map.c

+1 −1
Original line number Diff line number Diff line
@@ -158,7 +158,7 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data, 
	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, req_op(rq));



	if (map_data) {

		nr_pages = 1 << map_data->page_order;

		nr_pages = 1U << map_data->page_order;

		i = map_data->offset / PAGE_SIZE;

	}

	while (len) {

include/linux/blk-mq.h

+4 −4
Original line number Diff line number Diff line
@@ -963,11 +963,11 @@ blk_status_t blk_insert_cloned_request(struct request *rq); 


struct rq_map_data {

	struct page **pages;

	int page_order;

	int nr_entries;

	unsigned long offset;

	int null_mapped;

	int from_user;

	unsigned short page_order;

	unsigned short nr_entries;

	bool null_mapped;

	bool from_user;

};



int blk_rq_map_user(struct request_queue *, struct request *,