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Subject: Re: [PATCH v2 00/10] fsdax,xfs: Add reflink&dedupe support for fsdax
To:     Shiyang Ruan <ruansy.fnst@fujitsu.com>,
        linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
        linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org
Cc:     darrick.wong@oracle.com, dan.j.williams@intel.com,
        willy@infradead.org, jack@suse.cz, viro@zeniv.linux.org.uk,
        linux-btrfs@vger.kernel.org, ocfs2-devel@oss.oracle.com,
        david@fromorbit.com, hch@lst.de, rgoldwyn@suse.de
References: <20210226002030.653855-1-ruansy.fnst@fujitsu.com>
From:   Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Message-ID: <5e7766f9-0224-10be-6810-2e516e610191@linux.alibaba.com>
Date:   Tue, 9 Mar 2021 14:36:13 +0800
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hi,

First thanks for your patchset.
I'd like to know whether your patchset pass fstests? Thanks.

Regards,
Xiaoguang Wang

> This patchset is attempt to add CoW support for fsdax, and take XFS,
> which has both reflink and fsdax feature, as an example.
> 
> Changes from V1:
>   - Factor some helper functions to simplify dax fault code
>   - Introduce iomap_apply2() for dax_dedupe_file_range_compare()
>   - Fix mistakes and other problems
>   - Rebased on v5.11
> 
> One of the key mechanism need to be implemented in fsdax is CoW.  Copy
> the data from srcmap before we actually write data to the destance
> iomap.  And we just copy range in which data won't be changed.
> 
> Another mechanism is range comparison.  In page cache case, readpage()
> is used to load data on disk to page cache in order to be able to
> compare data.  In fsdax case, readpage() does not work.  So, we need
> another compare data with direct access support.
> 
> With the two mechanism implemented in fsdax, we are able to make reflink
> and fsdax work together in XFS.
> 
> 
> Some of the patches are picked up from Goldwyn's patchset.  I made some
> changes to adapt to this patchset.
> 
> (Rebased on v5.11)
> ==
> 
> Shiyang Ruan (10):
>    fsdax: Factor helpers to simplify dax fault code
>    fsdax: Factor helper: dax_fault_actor()
>    fsdax: Output address in dax_iomap_pfn() and rename it
>    fsdax: Introduce dax_iomap_cow_copy()
>    fsdax: Replace mmap entry in case of CoW
>    fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero
>    iomap: Introduce iomap_apply2() for operations on two files
>    fsdax: Dedup file range to use a compare function
>    fs/xfs: Handle CoW for fsdax write() path
>    fs/xfs: Add dedupe support for fsdax
> 
>   fs/dax.c               | 532 +++++++++++++++++++++++++++--------------
>   fs/iomap/apply.c       |  51 ++++
>   fs/iomap/buffered-io.c |   2 +-
>   fs/remap_range.c       |  45 +++-
>   fs/xfs/xfs_bmap_util.c |   3 +-
>   fs/xfs/xfs_file.c      |  29 ++-
>   fs/xfs/xfs_inode.c     |   8 +-
>   fs/xfs/xfs_inode.h     |   1 +
>   fs/xfs/xfs_iomap.c     |  30 ++-
>   fs/xfs/xfs_iomap.h     |   1 +
>   fs/xfs/xfs_iops.c      |  11 +-
>   fs/xfs/xfs_reflink.c   |  16 +-
>   include/linux/dax.h    |   7 +-
>   include/linux/fs.h     |  15 +-
>   include/linux/iomap.h  |   7 +-
>   15 files changed, 550 insertions(+), 208 deletions(-)
>