dm snapshot: iterate origin and cow devices

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 led to badly calculated device limits if snapshot and origin were placed
on different types of disks.

Cc: stable@kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 54853773510c..a6ab98920cc3 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1899,8 +1899,14 @@ static int snapshot_iterate_devices(struct dm_target *ti,
                                     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;
 }