linux-kernel - Re: [RFC PATCH v4 07/11] fs: statx add write zeroes unmap attribute

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Message-ID: <20250506121102.GA21905@lst.de>
Date: Tue, 6 May 2025 14:11:02 +0200
From: Christoph Hellwig <hch@....de>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: Christoph Hellwig <hch@....de>, "Darrick J. Wong" <djwong@...nel.org>,
	linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
	linux-block@...r.kernel.org, dm-devel@...ts.linux.dev,
	linux-nvme@...ts.infradead.org, linux-scsi@...r.kernel.org,
	linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	tytso@....edu, john.g.garry@...cle.com, bmarzins@...hat.com,
	chaitanyak@...dia.com, shinichiro.kawasaki@....com,
	brauner@...nel.org, yi.zhang@...wei.com, chengzhihao1@...wei.com,
	yukuai3@...wei.com, yangerkun@...wei.com
Subject: Re: [RFC PATCH v4 07/11] fs: statx add write zeroes unmap attribute

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?