Eric Sandeen wrote:
(oops, get Andi's email right!)
> I've noticed that on 2.6.29-rcX, with Andi's patch
> (ab4c1424882be9cd70b89abf2b484add355712fa, dm: support barriers on
> simple devices) barriers are still getting rejected on these simple devices.
>
> The problem is in __generic_make_request():
>
> if (bio_barrier(bio) && bio_has_data(bio) &&
> (q->next_ordered == QUEUE_ORDERED_NONE)) {
> err = -EOPNOTSUPP;
> goto end_io;
> }
>
> and dm isn't flagging its queue as supporting ordered writes, so it's
> rejected here.
>
> Doing something like this:
>
> + if (t->barriers_supported)
> + blk_queue_ordered(q, QUEUE_ORDERED_DRAIN, NULL);
>
> somewhere in dm (I stuck it in dm_table_set_restrictions() - almost
> certainly the wrong thing to do) did get my dm-linear device to mount
> with xfs, w/o xfs complaining that its mount-time barrier tests failed.
>
> So what's the right way around this? What should dm (or md for that
> matter) advertise on their queues about ordered-ness? Should there be
> some sort of "QUEUE_ORDERED_PASSTHROUGH" or something to say "this level
> doesn't care, ask the next level" or somesuch? Or should it inherit the
> flag from the next level down? Ideas?
>
> Thanks,
> -Eric
>
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
