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Date: Fri, 3 Jul 2026 14:43:31 +0200
From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Joanne Koong <joannelkoong@gmail.com>, brauner@kernel.org, hch@lst.de,
	willy@infradead.org, hsiangkao@linux.alibaba.com,
	linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org,
	Jonathan Corbet <corbet@lwn.net>,
	Shuah Khan <skhan@linuxfoundation.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 18/18] Documentation: iomap: update docs to reflect
 iomap_next model
Message-ID: <20260703124331.GA26440@lst.de>
References: <20260701000949.1666714-1-joannelkoong@gmail.com> <20260701000949.1666714-19-joannelkoong@gmail.com> <20260702192658.GN9392@frogsfrogsfrogs> <CAJnrk1YZQOQ0D6p6qYx1BPvKQaDgZsrKzLbGZzaH8tUkj_OoOQ@mail.gmail.com> <20260703020020.GS9392@frogsfrogsfrogs>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Thu, Jul 02, 2026 at 07:00:20PM -0700, Darrick J. Wong wrote:
> The ->begin method can still set iomap::private and the ->end method can
> dispose of it, right?  Oh, wait, no, that doesn't work because you're
> talking about ->begin/->end passing something to the next ->begin.

Should we move ->private from struct iomap to struct iomap_iter?
That'll deal with the constness and the fact that private data
really is a per-operation thing.

That also reminds me that now that we actually still keep the low-level
begin/end ops we need to switch them to a calling convention that
passes the iter instead of the ugly container_of.  This is something
I wanted deferred until we get the iter conversion, but it turns out
that now leaves them untouched..

> Hm.  I was thinking that the signature for iomap_process could be
> cleaner if you didn't have to pass iomap/srcmap explicitly.
> iomap_process could do the (dangerous) casting from the (const struct
> iomap_iter *) to the (struct iomap *) pointers before calling ->begin
> and ->end.

I don't quite understand those part.