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Date: Wed, 28 Aug 2024 06:48:48 +0200
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Chandan Babu R <chandan.babu@oracle.com>,
	Christian Brauner <brauner@kernel.org>, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 01/10] iomap: handle a post-direct I/O invalidate race
 in iomap_write_delalloc_release
Message-ID: <20240828044848.GA31463@lst.de>
References: <20240827051028.1751933-1-hch@lst.de> <20240827051028.1751933-2-hch@lst.de> <20240827161416.GV865349@frogsfrogsfrogs>
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On Tue, Aug 27, 2024 at 09:14:16AM -0700, Darrick J. Wong wrote:
> Is there any chance that we could get stuck in a loop here?  I
> think it's the case that if SEEK_HOLE returns data_end == start_byte,
> then the next time through the loop, the SEEK_DATA will return something
> that is > start_byte.

Yes.

> Unless someone is very rapidly writing and
> punching the page cache?
> 
> Hmm but then if *xfs* is punching delalloc then we're we holding the
> iolock so who else could be doing that?

Yes.  It's only the async direct I/O completions that punch without
the lock.