From: Junichi Nomura <j-nomura@ce.jp.nec.com>
Date: Fri, 3 Oct 2014 21:27:11 +0000 (-0400)
Subject: block: use bio_clone_fast() in blk_rq_prep_clone()
X-Git-Tag: fixes-against-v3.18-rc2~51^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=11dfce509eaa35e8fc81cb50d0910c0e235fd7e2;p=pandora-kernel.git

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>
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