On Mon, 28 Mar 2011 15:31:57 +0200 Krzysztof Wojcik <krzysztof.wojcik@xxxxxxxxx> wrote: > Problem: > After raid4->raid0 takeover operation, another takeover operation > (e.g raid0->raid10) results "kernel oops". > Root cause: > Variables 'degraded' and 'plug' in mddev structure are not cleared > after raid45->raid0 takeover. > > This patch reset these variables. > > Signed-off-by: Krzysztof Wojcik <krzysztof.wojcik@xxxxxxxxx> > --- > drivers/md/raid0.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c > index c0ac457..5d47113 100644 > --- a/drivers/md/raid0.c > +++ b/drivers/md/raid0.c > @@ -603,6 +603,8 @@ static void *raid0_takeover_raid45(mddev_t *mddev) > mddev->new_chunk_sectors = mddev->chunk_sectors; > mddev->raid_disks--; > mddev->delta_disks = -1; > + mddev->degraded = 0; > + mddev->plug = NULL; > /* make sure it will be not marked as dirty */ > mddev->recovery_cp = MaxSector; > This is wrong. The raid0 'takeover' method is called while the raid5 array is still active, and mddev->plug and mddev->degraded are used by the active array. So you cannot just clear them like this. The new_* and delta_disks values are not used by an active array - also raid_disks isn't used - each personality keeps a copy of the effective raid_disks in it's private structure. So the ->plug must be cleared in the raid5 stop routine, and degraded should be cleared by level_store after calling ->stop on the raid5 and before calling ->run on the raid0. I have changed the patch to do that instead. Thanks, NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
