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Date:   Wed, 24 Oct 2018 10:32:37 -0400
From:   "Theodore Y. Ts'o" <tytso@mit.edu>
To:     NeilBrown <neilb@suse.com>, Andy Lutomirski <luto@kernel.org>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Peter Zijlstra <peterz@infradead.org>,
        Dmitry Safonov <dsafonov@virtuozzo.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
        Brian Gerst <brgerst@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-tip-commits@vger.kernel.org, jsimmons@infradead.org
Subject: Re: in_compat_syscall() returns from kernel thread for X86_32.
Message-ID: <20181024143237.GA27168@thunk.org>
Mail-Followup-To: "Theodore Y. Ts'o" <tytso@mit.edu>,
        NeilBrown <neilb@suse.com>, Andy Lutomirski <luto@kernel.org>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Peter Zijlstra <peterz@infradead.org>,
        Dmitry Safonov <dsafonov@virtuozzo.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
        Brian Gerst <brgerst@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-tip-commits@vger.kernel.org, jsimmons@infradead.org
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On Wed, Oct 24, 2018 at 09:15:34AM -0400, Theodore Y. Ts'o wrote:
> At least for ext4, the primary problem is that we want to use a 64-bit
> telldir/seekdir cookie if all 64-bits will make it to user space, and
> a 32-bit telldir cookie if only 32 bits will make it userspace.  This
> impacts NFS as well because if there are people who are still using
> NFSv2, which has 32-bit directory offsets, we need to constrain the
> telldir/seekdir cookies we give to NFS to be a 32 has as opposed to a
> 64-bit hash.

Are there anyone still using NFSv2, BTW?  One way of making the
problem *much* easier to sovle would be to drop NFSv2 support.  :-)

	       	      	       	     - Ted