linux-ext4 - Re: [RFC PATCH 1/1] Remove buffered failover for ext4 and block fops direct writes.

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Date: Wed, 1 May 2024 22:45:06 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Jeremy Bongio <bongiojp@...il.com>
Cc: Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
	linux-block@...r.kernel.org, Jeremy Bongio <jbongio@...gle.com>
Subject: Re: [RFC PATCH 1/1] Remove buffered failover for ext4 and block fops
 direct writes.

On Wed, May 01, 2024 at 04:15:33PM -0700, Jeremy Bongio wrote:
> From: Jeremy Bongio <jbongio@...gle.com>
> 
> ext4 and block fops would both failover to syncronous, buffered writes if
> the direct IO results in a short write where only a portion of the request
> was completed.
> 
> This patch changes the behavior to simply return the number of bytes
> written if the direct write is short.

Please don't combine ext4 and block changes in a single patch.  Please
also explain why you want to change things.

AFAIK this is simply the historic behavior of the old direct I/O code
that's been around forever.  I think the XFS semantics make a lot more
sense, but people might rely on this one way or another.