[Drbd-dev] [DRBD-8.0 PATCH] Fix deadlock between transfer log and
lars.ellenberg at linbit.com
Mon Jan 14 10:07:48 CET 2008
On Fri, Jan 11, 2008 at 10:29:57AM -0500, Graham, Simon wrote:
> The attached patches fix some deadlocks between the transfer log and
> resync - when the TL is in use (previously only protocols A and B but
> now all protocols), if there is a request on the TL that conflicts with
> a resync region, the code would deadlock with the resync processing
> waiting for the AL area to be clean and new requests that might lead to
> a barrier that would clear out the TL blocked by the resync.
> The attached patches include the following:
> 1. Non-TCQ DRBD Barrier implementation on target now flushes
> disk to force cached data to disk.
this is correct, we should do that.
> 2. A deadlock between resync and requests sitting in the TL
> is fixed - if a resync request is started that conflicts
> with entries in the TL, a DRBD barrier is initiated - this
> will clear up the TL when the barrier ack is received and
> allow the resync to procede.
> 3. When changing role from Primary, it is necessary to clear out
> transfer log - do this by initiating barrier
> 4. When SyncTarget is also Primary, it is possible for
> to never make progress due to entries in tl that will not be flushed.
> Change code to initiate barrier IF conflict with AL is found.
these will be handled differently and more generically,
as recently discussed in the "Crash in lru_cache.c" thread.
: Lars Ellenberg Tel +43-1-8178292-55 :
: LINBIT Information Technologies GmbH Fax +43-1-8178292-82 :
: Vivenotgasse 48, A-1120 Vienna/Europe http://www.linbit.com :
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