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Date:   Thu, 12 Oct 2023 08:02:31 -0700
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Catherine Hoang <catherine.hoang@oracle.com>,
        linux-xfs@vger.kernel.org
Subject: Re: [PATCH v3] xfs: allow read IO and FICLONE to run concurrently
Message-ID: <20231012150231.GE21298@frogsfrogsfrogs>
References: <20231012010845.64286-1-catherine.hoang@oracle.com>
 <ZSevmga8j3dNl34J@infradead.org>
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On Thu, Oct 12, 2023 at 01:34:34AM -0700, Christoph Hellwig wrote:
> On Wed, Oct 11, 2023 at 06:08:45PM -0700, Catherine Hoang wrote:
> > Clone operations and read IO do not change any data in the source file, so they
> > should be able to run concurrently. Demote the exclusive locks taken by FICLONE
> > to shared locks to allow reads while cloning. While a clone is in progress,
> > writes will take the IOLOCK_EXCL, so they block until the clone completes.
> 
> FYI, the first two lines are too long for the normal commit log format.
> 
> Can you provide a justification for the change, i.e. worksloads for
> which this matters, and what metrics are improved?

Catherine started with this,
https://lore.kernel.org/linux-xfs/8911B94D-DD29-4D6E-B5BC-32EAF1866245@oracle.com/

and the rest of us whittled it down to the single patch you see here.
Sections 1-2 are still relevant; S3 was the path not taken.

The commit message should Link: to that.

--D