From: "Darrick J. Wong" <djwong@kernel.org>
To: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc: Christoph Hellwig <hch@lst.de>,
linux-xfs@vger.kernel.org, dan.j.williams@intel.com,
david@fromorbit.com, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev,
rgoldwyn@suse.de, viro@zeniv.linux.org.uk, willy@infradead.org,
Ritesh Harjani <riteshh@linux.ibm.com>
Subject: Re: [PATCH v9 5/8] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero
Date: Thu, 16 Sep 2021 15:55:44 -0700 [thread overview]
Message-ID: <20210916225544.GF34830@magnolia> (raw)
In-Reply-To: <9fb0c82f-b2ae-82e3-62df-f0a473ed6395@fujitsu.com>
On Thu, Sep 16, 2021 at 04:49:19PM +0800, Shiyang Ruan wrote:
>
>
> On 2021/9/16 14:16, Christoph Hellwig wrote:
> > On Wed, Sep 15, 2021 at 06:44:58PM +0800, Shiyang Ruan wrote:
> > > + rc = dax_direct_access(iomap->dax_dev, pgoff, 1, &kaddr, NULL);
> > > + if (rc < 0)
> > > + goto out;
> > > + memset(kaddr + offset, 0, size);
> > > + if (srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) {
> >
> > Should we also check that ->dax_dev for iomap and srcmap are different
> > first to deal with case of file system with multiple devices?
>
> I have not thought of this case. Isn't it possible to CoW between different
> devices?
There's nothing in the iomap API that prevents a filesystem from doing
that, though there are no filesystems today that do such a thing.
That said, if btrfs ever joins the fold (and adds DAX support) then they
could totally COW to a different device.
--D
>
>
> --
> Thanks,
> Ruan
>
> >
> > Otherwise looks good:
> >
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
> >
>
>
next prev parent reply other threads:[~2021-09-16 22:55 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-15 10:44 [PATCH v9 0/8] fsdax,xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-09-15 10:44 ` [PATCH v9 1/8] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-09-16 0:09 ` Darrick J. Wong
2021-09-16 1:36 ` Shiyang Ruan
2021-09-15 10:44 ` [PATCH v9 2/8] fsdax: Introduce dax_iomap_cow_copy() Shiyang Ruan
2021-09-15 10:44 ` [PATCH v9 3/8] fsdax: Replace mmap entry in case of CoW Shiyang Ruan
2021-09-16 14:51 ` kernel test robot
2021-09-15 10:44 ` [PATCH v9 4/8] fsdax: Convert dax_iomap_zero to iter model Shiyang Ruan
2021-09-16 0:11 ` Darrick J. Wong
2021-09-16 6:15 ` Christoph Hellwig
2021-09-15 10:44 ` [PATCH v9 5/8] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero Shiyang Ruan
2021-09-16 6:16 ` Christoph Hellwig
2021-09-16 8:49 ` Shiyang Ruan
2021-09-16 22:55 ` Darrick J. Wong [this message]
2021-09-15 10:44 ` [PATCH v9 6/8] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-09-16 6:17 ` Christoph Hellwig
2021-09-15 10:45 ` [PATCH v9 7/8] xfs: support CoW in fsdax mode Shiyang Ruan
2021-09-16 0:22 ` Darrick J. Wong
2021-09-16 6:32 ` Christoph Hellwig
2021-09-17 15:33 ` Darrick J. Wong
2021-09-21 8:14 ` Christoph Hellwig
2021-09-16 6:23 ` Christoph Hellwig
2021-09-16 8:51 ` Shiyang Ruan
2021-09-15 10:45 ` [PATCH v9 8/8] xfs: Add dax dedupe support Shiyang Ruan
2021-09-16 0:30 ` Darrick J. Wong
2021-09-16 4:01 ` Shiyang Ruan
2021-09-16 4:18 ` Darrick J. Wong
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