From: Tao Ma <tao.ma@oracle.com>
Date: Wed, 23 Jun 2010 23:43:57 +0000 (+0800)
Subject: block: Don't count_vm_events for discard bio in submit_bio.
X-Git-Tag: v2.6.35.3~269^2
X-Git-Url: https://rtime.felk.cvut.cz/gitweb/linux-imx.git/commitdiff_plain/1b99973f1c82707e46e8cb9416865a1e955e8f8c

block: Don't count_vm_events for discard bio in submit_bio.

In submit_bio, we count vm events by check READ/WRITE.
But actually DISCARD_NOBARRIER also has the WRITE flag set.
It looks as if in blkdev_issue_discard, we also add a
page as the payload and the bio_has_data check isn't enough.
So add another check for discard bio.

Signed-off-by: Tao Ma <tao.ma@oracle.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
---

diff --git a/block/blk-core.c b/block/blk-core.c
index 3deca77e0254..f0640d7f800f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1583,7 +1583,7 @@ void submit_bio(int rw, struct bio *bio)
 	 * If it's a regular read/write or a barrier with data attached,
 	 * go through the normal accounting stuff before submission.
 	 */
-	if (bio_has_data(bio)) {
+	if (bio_has_data(bio) && !(rw & (1 << BIO_RW_DISCARD))) {
 		if (rw & WRITE) {
 			count_vm_events(PGPGOUT, count);
 		} else {