linux-kernel - Re: [PATCH v3] f2fs: introduce flush

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Message-ID: <aJnLXmepVBD4V2QH@infradead.org>
Date: Mon, 11 Aug 2025 03:52:14 -0700
From: Christoph Hellwig <hch@...radead.org>
To: Chao Yu <chao@...nel.org>
Cc: jaegeuk@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v3] f2fs: introduce flush_policy sysfs entry

On Thu, Aug 07, 2025 at 11:48:38AM +0800, Chao Yu wrote:
> This patch introduces a new sysfs entry /sys/fs/f2fs/<disk>/flush_policy
> in order to tune performance of f2fs data flush flow.
> 
> For example, checkpoint will use REQ_FUA to persist CP metadata, however,
> some kind device has bad performance on REQ_FUA command, result in that
> checkpoint being blocked for long time, w/ this sysfs entry, we can give
> an option to use REQ_PREFLUSH command instead of REQ_FUA during checkpoint,
> it can help to mitigate long latency of checkpoint.

That's and odd place to deal with this.  If that's a real issue it
should be a block layer tweak to disable FUA, potentially with a quirk
entry in the driver to disable it rather than having to touch a file
system sysfs attribute.