linux-ext4 - Re: [PATCH v2] fcntl: Add 32bit filesystem mode

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Date:   Mon, 6 Jul 2020 10:54:45 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     "Theodore Ts'o" <tytso@....edu>
Cc:     Andreas Dilger <adilger.kernel@...ger.ca>,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        QEMU Developers <qemu-devel@...gnu.org>,
        Florian Weimer <fw@...eb.enyo.de>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Maydell <peter.maydell@...aro.org>
Subject: Re: [PATCH v2] fcntl: Add 32bit filesystem mode

On Tue, Jun 23, 2020 at 12:08 PM Peter Maydell <peter.maydell@...aro.org> wrote:
> On Fri, 29 May 2020 at 08:22, Linus Walleij <linus.walleij@...aro.org> wrote:
> >
> > It was brought to my attention that this bug from 2018 was
> > still unresolved: 32 bit emulators like QEMU were given
> > 64 bit hashes when running 32 bit emulation on 64 bit systems.
> >
> > This adds a flag to the fcntl() F_GETFD and F_SETFD operations
> > to set the underlying filesystem into 32bit mode even if the
> > file handle was opened using 64bit mode without the compat
> > syscalls.
>
> I somewhat belatedly got round to updating my QEMU patch
> that uses this new fcntl() flag to fix the bug. Sorry for
> the delay getting round to this. You can find the QEMU patch here:
> https://patchew.org/QEMU/20200623100101.6041-1-peter.maydell@linaro.org/
> (it's an RFC because obviously we won't put it into QEMU until
> the kernel side has gone upstream and the API is final.)
>
> What's the next step for moving this forward?

Ted, can you merge this patch?

It seems QEMU is happy and AFICT it uses the approach you want :)

Yours,
Linus Walleij