From: Mike Snitzer <snitzer@redhat.com>
To: Eric Wheeler <dm-devel@lists.ewheeler.net>
Cc: dm-devel@redhat.com, thornber@redhat.com,
Nikos Tsironis <ntsironis@arrikto.com>,
agk@redhat.com
Subject: Re: [PATCH 0/2] dm thin: Flush data device before committing metadata to avoid data corruption
Date: Wed, 4 Dec 2019 15:17:10 -0500 [thread overview]
Message-ID: <20191204201710.GA31432@redhat.com> (raw)
In-Reply-To: <alpine.LRH.2.11.1912041907490.11561@mx.ewheeler.net>
On Wed, Dec 04 2019 at 2:58pm -0500,
Eric Wheeler <dm-devel@lists.ewheeler.net> wrote:
> On Wed, 4 Dec 2019, Nikos Tsironis wrote:
>
> > The thin provisioning target maintains per thin device mappings that map
> > virtual blocks to data blocks in the data device.
> >
> > When we write to a shared block, in case of internal snapshots, or
> > provision a new block, in case of external snapshots, we copy the shared
> > block to a new data block (COW), update the mapping for the relevant
> > virtual block and then issue the write to the new data block.
> >
> > Suppose the data device has a volatile write-back cache and the
> > following sequence of events occur:
>
> For those with NV caches, can the data disk flush be optional (maybe as a
> table flag)?
IIRC block core should avoid issuing the flush if not needed. I'll have
a closer look to verify as much.
Mike
next prev parent reply other threads:[~2019-12-04 20:17 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 14:07 [PATCH 0/2] dm thin: Flush data device before committing metadata to avoid data corruption Nikos Tsironis
2019-12-04 14:07 ` [PATCH 1/2] dm thin metadata: Add support for a pre-commit callback Nikos Tsironis
2019-12-05 19:40 ` Mike Snitzer
2019-12-05 21:33 ` Nikos Tsironis
2019-12-04 14:07 ` [PATCH 2/2] dm thin: Flush data device before committing metadata Nikos Tsironis
2019-12-04 15:27 ` Joe Thornber
2019-12-04 16:17 ` Nikos Tsironis
2019-12-04 16:39 ` Mike Snitzer
2019-12-04 16:47 ` Nikos Tsironis
2019-12-04 19:58 ` [PATCH 0/2] dm thin: Flush data device before committing metadata to avoid data corruption Eric Wheeler
2019-12-04 20:17 ` Mike Snitzer [this message]
2019-12-05 15:31 ` Nikos Tsironis
2019-12-05 15:42 ` Mike Snitzer
2019-12-05 16:02 ` Nikos Tsironis
2019-12-05 22:34 ` Eric Wheeler
2019-12-06 15:14 ` Nikos Tsironis
2019-12-06 20:06 ` Eric Wheeler
2019-12-09 14:25 ` Nikos Tsironis
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