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Re: [dm-devel] [PATCH 0/8] dm: request-based dm-multipath

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.


Dr. Hannes Reinecke		      zSeries & Storage
hare 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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