linux-kernel - Re: [PATCH 2/4] xfs: convert delayed extents to unwritten when zeroing post eof blocks

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Message-ID: <ZfBI1l2l3TWw0tMV@infradead.org>
Date: Tue, 12 Mar 2024 05:21:42 -0700
From: Christoph Hellwig <hch@...radead.org>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: Zhang Yi <yi.zhang@...weicloud.com>, linux-xfs@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	hch@...radead.org, brauner@...nel.org, david@...morbit.com,
	tytso@....edu, jack@...e.cz, yi.zhang@...wei.com,
	chengzhihao1@...wei.com, yukuai3@...wei.com
Subject: Re: [PATCH 2/4] xfs: convert delayed extents to unwritten when
 zeroing post eof blocks

On Mon, Mar 11, 2024 at 08:37:37AM -0700, Darrick J. Wong wrote:
> > +convert_delay:
> > +	end_fsb = min(end_fsb, imap.br_startoff + imap.br_blockcount);
> > +	xfs_iunlock(ip, lockmode);
> > +	truncate_pagecache_range(inode, offset, XFS_FSB_TO_B(mp, end_fsb));
> > +	error = xfs_iomap_write_direct(ip, offset_fsb, end_fsb - offset_fsb,
> > +				       flags, &imap, &seq);
> 
> I expected this to be a direct call to xfs_bmapi_convert_delalloc.
> What was the reason not for using that?

Same here.  The fact that we even convert delalloc reservations in
xfs_iomap_write_direct is something that doesn't make much sense
given that we're punching out delalloc reservations before starting
direct I/O.