block: use bio_clone_fast() in blk_rq_prep_clone()

Request cloning clones bios in the request to track the completion
of each bio.
For that purpose, we can use bio_clone_fast() instead of bio_clone()
to avoid unnecessary allocation and copy of bvecs.

This patch reduces memory footprint of request-based device-mapper
(about 1-4KB for each request) and is a preparation for further
reduction of memory usage by removing unused bvec mempool.

Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Junichi Nomura 2014-10-03 17:27:11 -04:00 committed by Jens Axboe
parent 4a0efdc933
commit 11dfce509e

View File

@ -2926,7 +2926,7 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
blk_rq_init(NULL, rq);
__rq_for_each_bio(bio_src, rq_src) {
bio = bio_clone_bioset(bio_src, gfp_mask, bs);
bio = bio_clone_fast(bio_src, gfp_mask, bs);
if (!bio)
goto free_and_out;