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From:   =?UTF-8?Q?Andreas_Gr=C3=BCnbacher?= <andreas.gruenbacher@gmail.com>
Date:   Wed, 21 Jul 2021 04:26:47 +0200
Message-ID: <CAHpGcM+8cp81=bkzFf3sZfKREM9VbXfePpXrswNJOLVcwEnK7A@mail.gmail.com>
Subject: Re: [PATCH v4] iomap: support tail packing inline read
To:     "Darrick J. Wong" <djwong@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        linux-erofs@lists.ozlabs.org,
        Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Andreas Gruenbacher <andreas.gruenbacher@gmail.com>
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Am Mi., 21. Juli 2021 um 02:33 Uhr schrieb Gao Xiang
<hsiangkao@linux.alibaba.com>:
> > And since you can only kmap one page at a time, an inline read grabs the
> > first part of the data in "page one" and then we have to call
> > iomap_begin a second time get a new address so that we can read the rest
> > from "page two"?
>
> Nope, currently EROFS inline data won't cross page like this.
>
> But in principle, yes, I don't want to limit it to the current
> EROFS or gfs2 usage. I think we could make this iomap function
> more generally (I mean, I'd like to make the INLINE extent
> functionity as general as possible,

Nono. Can we please limit this patch what we actually need right now,
and worry about extending it later?

> my v1 original approach
> in principle can support any inline extent in the middle of
> file rather than just tail blocks, but zeroing out post-EOF
> needs another iteration) and I don't see it add more code and
> complexity.

Thanks,
Andreas