From 8c29dd356bdd6bc1ae74cd1d9b84ed7e7ac21891 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Tue, 2 Aug 2011 12:32:08 +0100
Subject: [PATCH] --- yaml --- r: 262214 b: refs/heads/master c:
 ed8b752bccf2560e305e25125721d2f0ac759e88 h: refs/heads/master v: v3

---
 [refs]                      |  2 +-
 trunk/drivers/md/dm-table.c | 43 +++++++++++++++++++++++++++++++++++++
 trunk/drivers/md/dm.c       |  1 -
 3 files changed, 44 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 19acbcb77633..2386246e6780 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 772ae5f54d69c38a5e3c4352c5fdbdaff141af21
+refs/heads/master: ed8b752bccf2560e305e25125721d2f0ac759e88
diff --git a/trunk/drivers/md/dm-table.c b/trunk/drivers/md/dm-table.c
index 259ce99302fc..986b8754bb08 100644
--- a/trunk/drivers/md/dm-table.c
+++ b/trunk/drivers/md/dm-table.c
@@ -1248,9 +1248,45 @@ static void dm_table_set_integrity(struct dm_table *t)
 			       blk_get_integrity(template_disk));
 }
 
+static int device_flush_capable(struct dm_target *ti, struct dm_dev *dev,
+				sector_t start, sector_t len, void *data)
+{
+	unsigned flush = (*(unsigned *)data);
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+
+	return q && (q->flush_flags & flush);
+}
+
+static bool dm_table_supports_flush(struct dm_table *t, unsigned flush)
+{
+	struct dm_target *ti;
+	unsigned i = 0;
+
+	/*
+	 * Require at least one underlying device to support flushes.
+	 * t->devices includes internal dm devices such as mirror logs
+	 * so we need to use iterate_devices here, which targets
+	 * supporting flushes must provide.
+	 */
+	while (i < dm_table_get_num_targets(t)) {
+		ti = dm_table_get_target(t, i++);
+
+		if (!ti->num_flush_requests)
+			continue;
+
+		if (ti->type->iterate_devices &&
+		    ti->type->iterate_devices(ti, device_flush_capable, &flush))
+			return 1;
+	}
+
+	return 0;
+}
+
 void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 			       struct queue_limits *limits)
 {
+	unsigned flush = 0;
+
 	/*
 	 * Copy table's limits to the DM device's request_queue
 	 */
@@ -1261,6 +1297,13 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 	else
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
 
+	if (dm_table_supports_flush(t, REQ_FLUSH)) {
+		flush |= REQ_FLUSH;
+		if (dm_table_supports_flush(t, REQ_FUA))
+			flush |= REQ_FUA;
+	}
+	blk_queue_flush(q, flush);
+
 	dm_table_set_integrity(t);
 
 	/*
diff --git a/trunk/drivers/md/dm.c b/trunk/drivers/md/dm.c
index 1000eaf984ef..52b39f335bb3 100644
--- a/trunk/drivers/md/dm.c
+++ b/trunk/drivers/md/dm.c
@@ -1808,7 +1808,6 @@ static void dm_init_md_queue(struct mapped_device *md)
 	blk_queue_make_request(md->queue, dm_request);
 	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
 	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
-	blk_queue_flush(md->queue, REQ_FLUSH | REQ_FUA);
 }
 
 /*