[dm-devel] [PATCH 0/8] dm: request-based dm-multipath
Hannes Reinecke
hare at suse.de
Wed Mar 11 12:28:29 UTC 2009
Hi Kiyoshi,
Kiyoshi Ueda wrote:
> Hi Hannes,
>
[ .. ]
>
> Suspend was broken.
> dm_suspend() recognized that suspend completed while some requests
> were still in flight. So we could swap/free the in-use table while
> there was in_flight request.
> The patch is like the attached one, although it is not finalized and
> I'm testing now.
> I'll post an updated patch-set including the attached patch
> this week or next week.
>
>
> ---
> drivers/md/dm.c | 236 ++++++++++++++++++++++++++++++++++----------------------
> 1 file changed, 144 insertions(+), 92 deletions(-)
>
> Index: 2.6.29-rc2/drivers/md/dm.c
> ===================================================================
> --- 2.6.29-rc2.orig/drivers/md/dm.c
> +++ 2.6.29-rc2/drivers/md/dm.c
> @@ -701,11 +701,17 @@ static void free_bio_clone(struct reques
> }
> }
>
> -static void dec_rq_pending(struct dm_rq_target_io *tio)
> +/*
> + * XXX: Not taking queue lock for efficiency.
> + * For correctness, waiters will check that again with queue lock held.
> + * No false negative because this function will be called everytime
> + * in_flight is decremented.
> + */
> +static void rq_completed(struct mapped_device *md)
> {
> - if (!atomic_dec_return(&tio->md->pending))
> + if (!md->queue->in_flight)
> /* nudge anyone waiting on suspend queue */
> - wake_up(&tio->md->wait);
> + wake_up(&md->wait);
> }
>
Hmm. Don't think that's a good idea. Either take the spinlock here or
in_flight should be atomic.
Apart from this I'll give it a shot.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare at suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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