linux-kernel - [39/91] dm snapshot: iterate origin and cow devices

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Date:	Tue, 24 Aug 2010 15:42:01 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Mikulas Patocka <mpatocka@...hat.com>,
	Alasdair G Kergon <agk@...hat.com>
Subject: [39/91] dm snapshot: iterate origin and cow devices

2.6.34-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Mikulas Patocka <mpatocka@...hat.com>

commit 1e5554c8428bc7209a83e2d07ca724be4d981ce3 upstream.

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.

Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Reviewed-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Alasdair G Kergon <agk@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

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

--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -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;
 
-	return fn(ti, snap->origin, 0, ti->len, data);
+	r = 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;
 }
 
 


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