[dm-devel] [PATCH 1/4] Iterate both origin and snapshot devices

[Mikulas Patocka <mpatocka redhat com>]

Iterate both origin and snapshot devices

iterate_devices method should call the callback for all the devices where
the bio may be remapped. Thus, snapshot_iterate_devices should call the callback
for both snapshot and origin underlying devices because it remaps some bios
to the snapshot and some to the origin.

snapshot_iterate_devices called the callback only for the origin device.
This lead to badly calculated device limits if snapshot and origin were placed
on different types of disks.

Signed-off-by: Mikulas Patocka <mpatocka redhat com>

---
 drivers/md/dm-snap.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6.34-rc1-devel/drivers/md/dm-snap.c
===================================================================
--- linux-2.6.34-rc1-devel.orig/drivers/md/dm-snap.c	2010-03-12 14:24:39.000000000 +0100
+++ linux-2.6.34-rc1-devel/drivers/md/dm-snap.c	2010-03-12 14:30:30.000000000 +0100
@@ -1899,8 +1899,14 @@ static int snapshot_iterate_devices(stru
 				    iterate_devices_callout_fn fn, void *data)
 {
 	struct dm_snapshot *snap = ti->private;
+	int r;
+
+	r = fn(ti, snap->origin, 0, ti->len, data);
 
-	return fn(ti, snap->origin, 0, ti->len, data);
+	if (!r)
+		r = fn(ti, snap->cow, 0, get_dev_size(snap->cow->bdev), data);
+
+	return r;
 }