From: mchristi@redhat.com <mchristi@redhat.com>
Date: Tue, 23 Sep 2008 11:40:39 -0500
Subject: [scsi] failfast bit setting in dm-multipath/multipath
Message-id: 1222188039-6324-1-git-send-email-mchristi@redhat.com
O-Subject: [PATCH 1/1] PATCH RHEL 5.3: Regression: fix failfast bit setting in dm-multipath/multipath (fix perf regression)
Bugzilla: 463470

From: Mike Christie <mchristi@redhat.com>

For BZ 463470.

This fixes the performance drop when using multipath that Jeff and
Sanjay saw yesterday.

I set the REQ flag instead of the BIO one for compat support.
The REQ flag actually maps to bio barriers so
this is why we get a drop in performance and the sync caches
and sync IO (my git trees must have got messed and so when I reported
sync caches to Alasdair and Milan my compat patch had went into that
branch).

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index a82f4c3..b96d7c3 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -868,10 +868,10 @@ static int multipath_map(struct dm_target *ti, struct bio *bio,
 	map_context->ptr = mpio;
 	/*
 	 * We set both incase 3rd party drivers were only checking
-	 * for REQ_FAILFAST.
+	 * for BIO_RW_FAILFAST.
 	 */
 	bio->bi_rw |= (1 << BIO_RW_FAILFAST_TRANSPORT);
-	bio->bi_rw |= (1 << REQ_FAILFAST);
+	bio->bi_rw |= (1 << BIO_RW_FAILFAST);
 	r = map_io(m, bio, mpio, 0);
 	if (r < 0 || r == DM_MAPIO_REQUEUE)
 		mempool_free(mpio, m->mpio_pool);
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index 756117e..c646100 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -180,10 +180,10 @@ static int multipath_make_request (request_queue_t *q, struct bio * bio)
 	mp_bh->bio.bi_bdev = multipath->rdev->bdev;
 	/*
 	 * We set both incase 3rd party drivers were only checking
-	 * for REQ_FAILFAST.
+	 * for BIO_RW_FAILFAST.
 	 */
 	mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST_TRANSPORT);
-	mp_bh->bio.bi_rw |= (1 << REQ_FAILFAST);
+	mp_bh->bio.bi_rw |= (1 << BIO_RW_FAILFAST);
 	mp_bh->bio.bi_end_io = multipath_end_request;
 	mp_bh->bio.bi_private = mp_bh;
 	generic_make_request(&mp_bh->bio);