From 6d4402070503c3b104dbc5e84c93deb2e9db2cc4 Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Fri, 21 Dec 2012 20:23:37 +0000
Subject: [PATCH] --- yaml --- r: 347961 b: refs/heads/master c:
 23508a96cd2e857d57044a2ed7d305f2d9daf441 h: refs/heads/master i:   347959:
 fada6796d458aa491de174501c28080273497987 v: v3

---
 [refs]                |  2 +-
 trunk/drivers/md/dm.c | 44 ++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/[refs] b/[refs]
index 41e8f0e5249a..72bfa9350c2d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d54eaa5a0fde0a202e4e91f200f818edcef15bee
+refs/heads/master: 23508a96cd2e857d57044a2ed7d305f2d9daf441
diff --git a/trunk/drivers/md/dm.c b/trunk/drivers/md/dm.c
index 77e6eff41cae..5401cdce0fc5 100644
--- a/trunk/drivers/md/dm.c
+++ b/trunk/drivers/md/dm.c
@@ -1174,7 +1174,28 @@ static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti)
 	ci->sector_count = 0;
 }
 
-static int __clone_and_map_discard(struct clone_info *ci)
+typedef unsigned (*get_num_requests_fn)(struct dm_target *ti);
+
+static unsigned get_num_discard_requests(struct dm_target *ti)
+{
+	return ti->num_discard_requests;
+}
+
+static unsigned get_num_write_same_requests(struct dm_target *ti)
+{
+	return ti->num_write_same_requests;
+}
+
+typedef bool (*is_split_required_fn)(struct dm_target *ti);
+
+static bool is_split_required_for_discard(struct dm_target *ti)
+{
+	return ti->split_discard_requests;
+}
+
+static int __clone_and_map_changing_extent_only(struct clone_info *ci,
+						get_num_requests_fn get_num_requests,
+						is_split_required_fn is_split_required)
 {
 	struct dm_target *ti;
 	sector_t len;
@@ -1185,15 +1206,15 @@ static int __clone_and_map_discard(struct clone_info *ci)
 			return -EIO;
 
 		/*
-		 * Even though the device advertised discard support,
-		 * that does not mean every target supports it, and
+		 * Even though the device advertised support for this type of
+		 * request, that does not mean every target supports it, and
 		 * reconfiguration might also have changed that since the
 		 * check was performed.
 		 */
-		if (!ti->num_discard_requests)
+		if (!get_num_requests || !get_num_requests(ti))
 			return -EOPNOTSUPP;
 
-		if (!ti->split_discard_requests)
+		if (is_split_required && !is_split_required(ti))
 			len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
 		else
 			len = min(ci->sector_count, max_io_len(ci->sector, ti));
@@ -1206,6 +1227,17 @@ static int __clone_and_map_discard(struct clone_info *ci)
 	return 0;
 }
 
+static int __clone_and_map_discard(struct clone_info *ci)
+{
+	return __clone_and_map_changing_extent_only(ci, get_num_discard_requests,
+						    is_split_required_for_discard);
+}
+
+static int __clone_and_map_write_same(struct clone_info *ci)
+{
+	return __clone_and_map_changing_extent_only(ci, get_num_write_same_requests, NULL);
+}
+
 static int __clone_and_map(struct clone_info *ci)
 {
 	struct bio *bio = ci->bio;
@@ -1215,6 +1247,8 @@ static int __clone_and_map(struct clone_info *ci)
 
 	if (unlikely(bio->bi_rw & REQ_DISCARD))
 		return __clone_and_map_discard(ci);
+	else if (unlikely(bio->bi_rw & REQ_WRITE_SAME))
+		return __clone_and_map_write_same(ci);
 
 	ti = dm_table_find_target(ci->map, ci->sector);
 	if (!dm_target_is_valid(ti))