linux-kernel - Re: [PATCH v9 05/15] xfs: ignore HW which cannot atomic write a single block

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Message-ID: <20250429144446.GD25655@frogsfrogsfrogs>
Date: Tue, 29 Apr 2025 07:44:46 -0700
From: "Darrick J. Wong" <djwong@...nel.org>
To: Christoph Hellwig <hch@....de>
Cc: John Garry <john.g.garry@...cle.com>, brauner@...nel.org,
	viro@...iv.linux.org.uk, jack@...e.cz, cem@...nel.org,
	linux-fsdevel@...r.kernel.org, dchinner@...hat.com,
	linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	ojaswin@...ux.ibm.com, ritesh.list@...il.com,
	martin.petersen@...cle.com, linux-ext4@...r.kernel.org,
	linux-block@...r.kernel.org, catherine.hoang@...cle.com,
	linux-api@...r.kernel.org
Subject: Re: [PATCH v9 05/15] xfs: ignore HW which cannot atomic write a
 single block

On Tue, Apr 29, 2025 at 02:21:05PM +0200, Christoph Hellwig wrote:
> On Fri, Apr 25, 2025 at 04:44:54PM +0000, John Garry wrote:
> > +	/* Configure hardware atomic write geometry */
> > +	xfs_buftarg_config_atomic_writes(mp->m_ddev_targp);
> > +	if (mp->m_logdev_targp && mp->m_logdev_targp != mp->m_ddev_targp)
> > +		xfs_buftarg_config_atomic_writes(mp->m_logdev_targp);
> > +	if (mp->m_rtdev_targp && mp->m_rtdev_targp != mp->m_ddev_targp)
> > +		xfs_buftarg_config_atomic_writes(mp->m_rtdev_targp);
> 
> So this can't be merged into xfs_setsize_buftarg as suggeted last round
> instead of needing yet another per-device call into the buftarg code?

Oh, heh, I forgot that xfs_setsize_buftarg is called a second time by
xfs_setup_devices at the end of fill_super.  xfs_setup_devices is a
better place to call xfs_buftarg_config_atomic_writes.

I don't like the idea of merging the hw atomic write detection into
xfs_setsize_buftarg itself because (a) it gets called for the data
device before we've read the fs blocksize so the validation is
meaningless and (b) that makes xfs_setsize_buftarg's purpose less
cohesive.

--D