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    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 <>

    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 <>
    Reviewed-by: Mike Snitzer <>
    Signed-off-by: Alasdair G Kergon <>
    Signed-off-by: Greg Kroah-Hartman <>

    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;

     \ /
      Last update: 2010-08-25 01:51    [W:0.046 / U:0.784 seconds]
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