From: Greg KH on
2.6.34-stable review patch. If anyone has any objections, please let us know.

------------------

From: Tao Ma <tao.ma(a)oracle.com>

commit 1b99973f1c82707e46e8cb9416865a1e955e8f8c upstream.

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(a)oracle.com>
Signed-off-by: Jens Axboe <jaxboe(a)fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de>

---
block/blk-core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1556,7 +1556,7 @@ 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 {


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