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Date: Tue, 6 May 2025 14:11:02 +0200
From: Christoph Hellwig <hch@lst.de>
To: Zhang Yi <yi.zhang@huaweicloud.com>
Cc: Christoph Hellwig <hch@lst.de>, "Darrick J. Wong" <djwong@kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
	linux-block@vger.kernel.org, dm-devel@lists.linux.dev,
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	brauner@kernel.org, yi.zhang@huawei.com, chengzhihao1@huawei.com,
	yukuai3@huawei.com, yangerkun@huawei.com
Subject: Re: [RFC PATCH v4 07/11] fs: statx add write zeroes unmap attribute
Message-ID: <20250506121102.GA21905@lst.de>
References: <20250421021509.2366003-1-yi.zhang@huaweicloud.com> <20250421021509.2366003-8-yi.zhang@huaweicloud.com> <20250505132208.GA22182@lst.de> <20250505142945.GJ1035866@frogsfrogsfrogs> <c7d8d0c3-7efa-4ee6-b518-f8b09ec87b73@huaweicloud.com> <20250506043907.GA27061@lst.de> <64c8b62a-83ba-45be-a83e-62b6ad8d6f22@huaweicloud.com>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Tue, May 06, 2025 at 07:16:56PM +0800, Zhang Yi wrote:
> Sorry, but I don't understand your suggestion. The
> STATX_ATTR_WRITE_ZEROES_UNMAP attribute only indicate whether the bdev
> and the block device that under the specified file support unmap write
> zeroes commoand. It does not reflect whether the bdev and the
> filesystems support FALLOC_FL_WRITE_ZEROES. The implementation of
> FALLOC_FL_WRITE_ZEROES doesn't fully rely on the unmap write zeroes
> commoand now, users simply refer to this attribute flag to determine
> whether to use FALLOC_FL_WRITE_ZEROES when preallocating a file.
> So, STATX_ATTR_WRITE_ZEROES_UNMAP and FALLOC_FL_WRITE_ZEROES doesn't
> have strong relations, why do you suggested to put this into the ext4
> and bdev patches that adding FALLOC_FL_WRITE_ZEROES?

So what is the point of STATX_ATTR_WRITE_ZEROES_UNMAP?