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Date:   Mon, 7 Nov 2016 07:01:03 -0800
From:   Christoph Hellwig <>
To:     "Kirill A. Shutemov" <>
Cc:     Christoph Hellwig <>, Jan Kara <>,
        "Kirill A. Shutemov" <>,
        Theodore Ts'o <>,
        Andreas Dilger <>,
        Jan Kara <>,
        Andrew Morton <>,
        Alexander Viro <>,
        Hugh Dickins <>,
        Andrea Arcangeli <>,
        Dave Hansen <>,
        Vlastimil Babka <>,
        Matthew Wilcox <>,
        Ross Zwisler <>,,,,,
Subject: Re: [PATCHv3 15/41] filemap: handle huge pages in

On Mon, Nov 07, 2016 at 02:13:05PM +0300, Kirill A. Shutemov wrote:
> It looks like a huge limitation to me.

The DAX PMD fault code can live just fine with it.  And without it
performance would suck anyway.

> I'm looking onto iomap_write_actor(): we still calculate 'offset' and
> 'bytes' based on PAGE_SIZE before we even get the page.
> This way we limit outself to PAGE_SIZE per-iteration.

Of course it does, given that it does not support huge pages _yet_.
But the important part is that this is now isolate to the highlevel
code, and the fs can get iomap_begin calls for a huge page (or in fact
much larger sizes than that).

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