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Date: Thu, 24 Sep 2026 15:33:20 -0700
From: "Darrick J. Wong" <djwong@kernel.org>
To: Andrea Parri <parri.andrea@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>,
	Carlos Maiolino <cem@kernel.org>,
	Joanne Koong <joannelkoong@gmail.com>,
	Brian Foster <bfoster@redhat.com>,
	Christoph Hellwig <hch@infradead.org>,
	Damien Le Moal <dlemoal@kernel.org>, Hannes Reinecke <hare@suse.de>,
	Daniel Gomez <da.gomez@samsung.com>,
	Pankaj Raghav <p.raghav@samsung.com>,
	Dave Chinner <dchinner@redhat.com>, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH v2 1/4] iomap: don't resubmit an ioend after
 ->writeback_submit() failed
Message-ID: <20260924223320.GL2705364@frogsfrogsfrogs>
References: <20260924091203.198225-1-parri.andrea@gmail.com>
 <20260924091203.198225-2-parri.andrea@gmail.com>
 <20260924184910.GI2705364@frogsfrogsfrogs>
 <20260924203013.9967-1-parri.andrea@gmail.com>
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In-Reply-To: <20260924203013.9967-1-parri.andrea@gmail.com>

On Thu, Sep 24, 2026 at 10:30:07PM +0200, Andrea Parri wrote:
> On Thu, Sep 24, 2026 at 11:49:10AM -0700, Darrick J. Wong wrote:
> > I looked around the codebase and saw that iomap_writepages also calls
> > ->writeback_submit.  Does that need to null out wb_ctx?
> > 
> > My guess is that none of the callers do anything with wpc after
> > iomap_writepages returns so it's not harming anyone, but we should drop
> > the stale context too, right?
> 
> Your guess is right: that ->writeback_submit() call is the last thing
> iomap_writepages() does, and all of its callers (xfs, gfs2, zonefs,
> exfat, fuse, ntfs, ntfs3) have the wpc on the stack for that single
> call, so wb_ctx is never looked at again.  Christoph made the same
> point on v1 [1], and the last paragraph of the commit message now
> spells it out.
> 
> Clearing it there as well would be harmless but dead code, so I'd
> rather leave it out; happy to add it if you feel strongly about it.
> 
> [1] https://lore.kernel.org/all/arITXTsUhrA0N-qr@infradead.org/

LOL ok thanks for the reminder.  My brain is fried this week, in a good
way. ;)

--D

> Thanks!
>   Andrea
>