linux-kernel - Re: [PATCH] xfs: Remove i_rwsem lock in buffered read

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Message-ID: <Z5CLSmrBvp66WHPP@infradead.org>
Date: Tue, 21 Jan 2025 22:08:10 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Dave Chinner <david@...morbit.com>
Cc: Amir Goldstein <amir73il@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	Brian Foster <bfoster@...hat.com>,
	"Darrick J. Wong" <djwong@...nel.org>,
	Chi Zhiling <chizhiling@....com>, cem@...nel.org,
	linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	Chi Zhiling <chizhiling@...inos.cn>,
	John Garry <john.g.garry@...cle.com>
Subject: Re: [PATCH] xfs: Remove i_rwsem lock in buffered read

On Sat, Jan 18, 2025 at 09:19:15AM +1100, Dave Chinner wrote:
> And, quite frankly, the fact the bcachefs solution also covers AIO
> DIO in flight (which i_rwsem based locking does not!) means it is a
> more robust solution than trying to rely on racy i_dio_count hacks
> and folio residency in the page cache...

The original i_rwsem (still i_iolock then) scheme did that, but the
core locking maintainers asked us to remove the non-owner unlocks,
so I did that.  It turns out later we got officially sanctioned
non-owner unlocks, so we could have easily add this back.  I did that
5 years ago, but reception was lukewarm:

http://git.infradead.org/?p=users/hch/xfs.git;a=shortlog;h=refs/heads/i_rwsem-non_owner