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Date:   Mon, 27 Mar 2023 18:04:32 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Qu Wenruo <wqu@suse.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Qu Wenruo <quwenruo.btrfs@gmx.com>,
        linux-btrfs@vger.kernel.org, David Sterba <dsterba@suse.com>
Subject: Re: [PATCH v5 03/13] btrfs: introduce a new helper to submit read
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On Tue, Mar 28, 2023 at 09:01:57AM +0800, Qu Wenruo wrote:
> > Well, if did just call btrfs_submit_chunk, the RST lookup would ensure
> > you only get the length of the RST mapping, and you get the behavior
> > you want without duplication.  We'd need to make it non-static (and
> > document it), but I'd still be much happier about that than yet another
> > I/O submission interface.
> 
> But in that case, wouldn't we just error out?

btrfs_submit_chunk is greedy.  But yes, if there was no mapping at all
I guess it would error out and we'd need to find a way to handle that.
But that still seems better than duplicating the logic again.