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Message-ID: <1467143000.3504.431.camel@hpe.com>
Date: Tue, 28 Jun 2016 19:43:26 +0000
From: "Kani, Toshimitsu" <toshi.kani@....com>
To: "snitzer@...hat.com" <snitzer@...hat.com>
CC: "linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-nvdimm@...ts.01.org" <linux-nvdimm@...ts.01.org>,
"dm-devel@...hat.com" <dm-devel@...hat.com>,
"agk@...hat.com" <agk@...hat.com>
Subject: Re: [PATCH 0/2] fix dm-snap for dax
Sorry, subject line should be "[PATCH 0/2] fix dm-snap for dax"
-Toshi
On Tue, 2016-06-28 at 13:37 -0600, Toshi Kani wrote:
> I noticed that dm-snap reloads DM table of target mapped-device, which
> fails for dax-capable device after dax support is added. Ideally,
> adding dax support to dm-snap solves the issue, but it cannot be done
> easily. This patch-set allows dm-snap to work with dax-capable target
> devices when bio-based operation is used.
>
> dax operation is unsupported with dm-snap, such that:
> a) After snapshot is taken, mount with dax option to a target device
> or a snapshot device fails. They can be mounted without dax.
> b) After snapshot is taken to a dax-mounted target device, any writes
> to the target device fails (EIO).
>
> b) can be protected by changing lvcreate to fail when snapshot is
> requested to a dax-mounted target device.
>
> - Patch 1 solves an error when lvremove is made to a snapshot device.
> - Patch 2 solves an error when lvcreate --snapshot is made to a dax-
> capable device.
>
> ---
> Toshi Kani (2):
> 1/2 dm: update table type check for dax
> 2/2 dm snap: add fake origin_direct_access
>
> ---
> drivers/md/dm-ioctl.c | 11 ++++++++++-
> drivers/md/dm-snap.c | 8 ++++++++
> 2 files changed, 18 insertions(+), 1 deletion(-)
> _______________________________________________
> Linux-nvdimm mailing list
> Linux-nvdimm@...ts.01.org
> https://lists.01.org/mailman/listinfo/linux-nvdimm
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