From: Jeff Moyer <jmoyer@redhat.com>
Date: Thu, 25 Mar 2010 16:53:11 -0400
Subject: [block] introduce the rq_is_sync macro
Message-id: <1269535995-21213-2-git-send-email-jmoyer@redhat.com>
Patchwork-id: 23757
O-Subject: [RHEL5 PATCH 1/5] block: introduce the rq_is_sync macro
Bugzilla: 574285
RH-Acked-by: Josef Bacik <josef@redhat.com>
RH-Acked-by: Vivek Goyal <vgoyal@redhat.com>
RH-Acked-by: Jerome Marchand <jmarchan@redhat.com>

This is a partial backport of the following upstream commit:

  commit 9e2585a8a23f3a42f815b2a638725d85a921cd65
  Author: Jens Axboe <axboe@suse.de>
  Date:   Fri Jul 28 09:26:13 2006 +0200

    [PATCH] as-iosched: remove arq->is_sync member

    We can track this in struct request.

    Signed-off-by: Jens Axboe <axboe@suse.de>
    Signed-off-by: Nick Piggin <npiggin@suse.de>

This patch simply introduces an rq_is_sync() macro.  I chose not to backport
the as-iosched bits as I wanted to limit the scope of the change.  This is
related to bug 574285.  The rq_is_sync macro will be used by later patches
to CFQ to differentiate between O_DIRECT and buffered writes.
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c005442..99b4017 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -540,6 +540,11 @@ static inline int blk_do_io_stat(struct request *rq)
 
 #define rq_data_dir(rq)		((rq)->flags & 1)
 
+/*
+ * We regard a request as sync, if it's a READ or a SYNC write.
+ */
+#define rq_is_sync(rq)		(rq_data_dir((rq)) == READ || (rq)->flags & REQ_RW_SYNC)
+
 static inline int blk_queue_full(struct request_queue *q, int rw)
 {
 	if (rw == READ)