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Subject: Re: [PATCH v3 2/3] erofs: dax support for non-tailpacking regular
 file
To: Gao Xiang <hsiangkao@linux.alibaba.com>, linux-erofs@lists.ozlabs.org
Cc: linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev,
 LKML <linux-kernel@vger.kernel.org>, "Darrick J. Wong" <djwong@kernel.org>,
 Liu Bo <bo.liu@linux.alibaba.com>, Joseph Qi <joseph.qi@linux.alibaba.com>,
 Liu Jiang <gerry@linux.alibaba.com>, Huang Jianan <huangjianan@oppo.com>,
 Tao Ma <boyu.mt@taobao.com>
References: <20210805003601.183063-1-hsiangkao@linux.alibaba.com>
 <20210805003601.183063-3-hsiangkao@linux.alibaba.com>
From: Chao Yu <chao@kernel.org>
Message-ID: <7aa650b8-a853-368d-7a81-f435194eec33@kernel.org>
Date: Thu, 5 Aug 2021 11:01:43 +0800
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On 2021/8/5 8:36, Gao Xiang wrote:
> DAX is quite useful for some VM use cases in order to save guest
> memory extremely with minimal lightweight EROFS.
> 
> In order to prepare for such use cases, add preliminary dax support
> for non-tailpacking regular files for now.
> 
> Tested with the DRAM-emulated PMEM and the EROFS image generated by
> "mkfs.erofs -Enoinline_data enwik9.fsdax.img enwik9"
> 
> Cc: nvdimm@lists.linux.dev
> Cc: linux-fsdevel@vger.kernel.org
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> ---
>   Documentation/filesystems/erofs.rst |  2 +
>   fs/erofs/data.c                     | 42 +++++++++++++++++++-
>   fs/erofs/inode.c                    |  4 ++
>   fs/erofs/internal.h                 |  3 ++
>   fs/erofs/super.c                    | 59 ++++++++++++++++++++++++++++-
>   5 files changed, 106 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/filesystems/erofs.rst b/Documentation/filesystems/erofs.rst
> index 832839fcf4c3..ffd2ae7be511 100644
> --- a/Documentation/filesystems/erofs.rst
> +++ b/Documentation/filesystems/erofs.rst
> @@ -84,6 +84,8 @@ cache_strategy=%s      Select a strategy for cached decompression from now on:
>                                      It still does in-place I/O decompression
>                                      for the rest compressed physical clusters.
>   		       ==========  =============================================
> +dax                    Use direct access (no page cache).  See

dax or dax=%s

Otherwise, it looks good to me.

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,