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Date:   Sat, 20 Feb 2021 00:23:59 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc:     Theodore Ts'o <tytso@mit.edu>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        "linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: page->index limitation on 32bit system?
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On Sat, Feb 20, 2021 at 07:10:14AM +0800, Qu Wenruo wrote:
> 
> 
> On 2021/2/20 上午12:12, Theodore Ts'o wrote:
> > On Fri, Feb 19, 2021 at 08:37:30AM +0800, Qu Wenruo wrote:
> > > So it means the 32bit archs are already 2nd tier targets for at least
> > > upstream linux kernel?
> > 
> > At least as far as btrfs is concerned, anyway....
> 
> I'm afraid that would be the case.

btrfs already treats 32-bit arches as second class citizens.
I found a1fbc6750e212c5675a4e48d7f51d44607eb8756 by code inspection,
so clearly it hasn't been tested in five years.  I wouldn't recommend
that anybody use btrfs with a 32-bit kernel.