On Wednesday June 24, jens.axboe@xxxxxxxxxx wrote:
> On Wed, Jun 24 2009, Neil Brown wrote:
> > On Sunday June 21, ken.milmore@xxxxxxxxxxxxxx wrote:
> > > I thought I had better bump my previous post as this regression is still
> > > present in 2.6.29.5.
> >
> > Thanks Ken.
> >
> > >
> > > To recap, commit cec0707e40ae25794b5a2de7b7f03c51961f80d9 has broken
> > > write barriers on md raid1 block devices in 2.6.29 and later kernels.
> > > Reversing this commit appears to fix the problem.
> > >
> > > Please let me know if I'm harassing the wrong maintainers here!
> >
> > Jens,
> > have you had a chance to look at this?
>
> Yeah, I think it's the right way to go. I'll queue it up for .31 and we
> should put in in -stable as well.
Great, thanks.
NeilBrown
>
> >
> > I think the following patch is appropriate and should go in to
> > -stable.
> >
> > Thanks,
> > NeilBrown
> >
> >
> > From addd8b129835a63d6df9a38eae20caaa15de5988 Mon Sep 17 00:00:00 2001
> > From: NeilBrown <neilb@xxxxxxx>
> > Date: Wed, 24 Jun 2009 13:39:15 +1000
> > Subject: [PATCH] Restore barrier support for md and probably other virtual devices.
> >
> > The next_ordered flag is only meaningful for devices that use __make_request.
> > So move the test against next_ordered out of generic code and in to
> > __make_request
> >
> > Since this test was added, barriers have not worked on md, and (I
> > think) dm and similar devices that don't use __make_request and so
> > don't bother to set next_ordered.
> >
> > Cc: stable@xxxxxxxxxx
> > Cc: Ken Milmore <ken.milmore@xxxxxxxxxxxxxx>
> > Signed-off-by: NeilBrown <neilb@xxxxxxx>
> > ---
> > block/blk-core.c | 10 +++++-----
> > 1 files changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/block/blk-core.c b/block/blk-core.c
> > index b06cf5c..fc221aa 100644
> > --- a/block/blk-core.c
> > +++ b/block/blk-core.c
> > @@ -1172,6 +1172,11 @@ static int __make_request(struct request_queue *q, struct bio *bio)
> > const int unplug = bio_unplug(bio);
> > int rw_flags;
> >
> > + if (bio_barrier(bio) && bio_has_data(bio) &&
> > + (q->next_ordered == QUEUE_ORDERED_NONE)) {
> > + bio_endio(bio, -EOPNOTSUPP)
> > + return 0;
> > + }
> > /*
> > * low level driver can indicate that it wants pages above a
> > * certain limit bounced to low memory (ie for highmem, or even
> > @@ -1472,11 +1477,6 @@ static inline void __generic_make_request(struct bio *bio)
> > err = -EOPNOTSUPP;
> > goto end_io;
> > }
> > - if (bio_barrier(bio) && bio_has_data(bio) &&
> > - (q->next_ordered == QUEUE_ORDERED_NONE)) {
> > - err = -EOPNOTSUPP;
> > - goto end_io;
> > - }
> >
> > ret = q->make_request_fn(q, bio);
> > } while (ret);
> > --
> > 1.6.3.1
> >
>
> --
> Jens Axboe
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