From 7dab264f53ff7078c2cae9b3c2adb33158013e8b Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Fri, 11 Feb 2011 11:05:46 +0100
Subject: [PATCH] --- yaml --- r: 242239 b: refs/heads/master c:
 9d5a4e946ce5352f19400b6370f4cd8e72806278 h: refs/heads/master i:   242237:
 1bb3d13b5f5c4ecd6dbb82483270071e107cd152   242235:
 3383c1eab02c98de71867e612920d5c40247d994   242231:
 e5f3abc10d78a5f60a9e4c901b0fbcfea7d25219   242223:
 07d217058b392b96c371f4379e7213072e3ba6f6   242207:
 3fb295667ab8c517e6be13300cec0d8fb4d59d74   242175:
 039da57f2758b33536036a367841d25b55df1bdc v: v3

---
 [refs]                 |  2 +-
 trunk/block/blk-core.c | 29 +++++++++++++++++++++++++----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/[refs] b/[refs]
index 4c408bbe20c5..c07fefa5a79b 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: ae1b1539622fb46e51b4d13b3f9e5f4c713f86ae
+refs/heads/master: 9d5a4e946ce5352f19400b6370f4cd8e72806278
diff --git a/trunk/block/blk-core.c b/trunk/block/blk-core.c
index 05746093b45e..ab4a7696956d 100644
--- a/trunk/block/blk-core.c
+++ b/trunk/block/blk-core.c
@@ -737,6 +737,25 @@ static void freed_request(struct request_queue *q, int sync, int priv)
 		__freed_request(q, sync ^ 1);
 }
 
+/*
+ * Determine if elevator data should be initialized when allocating the
+ * request associated with @bio.
+ */
+static bool blk_rq_should_init_elevator(struct bio *bio)
+{
+	if (!bio)
+		return true;
+
+	/*
+	 * Flush requests do not use the elevator so skip initialization.
+	 * This allows a request to share the flush and elevator data.
+	 */
+	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
+		return false;
+
+	return true;
+}
+
 /*
  * Get a free request, queue_lock must be held.
  * Returns NULL on failure, with queue_lock held.
@@ -749,7 +768,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	struct request_list *rl = &q->rq;
 	struct io_context *ioc = NULL;
 	const bool is_sync = rw_is_sync(rw_flags) != 0;
-	int may_queue, priv;
+	int may_queue, priv = 0;
 
 	may_queue = elv_may_queue(q, rw_flags);
 	if (may_queue == ELV_MQUEUE_NO)
@@ -793,9 +812,11 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	rl->count[is_sync]++;
 	rl->starved[is_sync] = 0;
 
-	priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
-	if (priv)
-		rl->elvpriv++;
+	if (blk_rq_should_init_elevator(bio)) {
+		priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+		if (priv)
+			rl->elvpriv++;
+	}
 
 	if (blk_queue_io_stat(q))
 		rw_flags |= REQ_IO_STAT;