From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-xfs-owner@vger.kernel.org>
Received: from mail-yw0-f194.google.com ([209.85.161.194]:33590 "EHLO
        mail-yw0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1753461AbeBAA32 (ORCPT
        <rfc822;linux-xfs@vger.kernel.org>); Wed, 31 Jan 2018 19:29:28 -0500
MIME-Version: 1.0
In-Reply-To: <CAOQ4uxjMfZGMtbq2vRN8dL5QvgC0=UD-yWDbNib=dckDTFR0Nw@mail.gmail.com>
References: <1516952669-14769-1-git-send-email-amir73il@gmail.com>
 <20180126214404.GE9068@magnolia> <CAOQ4uxgVaGgwio=538-PP4QuRbcny6q0_CAeV-9bQEWBaxv2gA@mail.gmail.com>
 <20180129155054.GJ9359@magnolia> <CAOQ4uxjMfZGMtbq2vRN8dL5QvgC0=UD-yWDbNib=dckDTFR0Nw@mail.gmail.com>
From: Amir Goldstein <amir73il@gmail.com>
Date: Thu, 1 Feb 2018 02:29:27 +0200
Message-ID: <CAOQ4uxhXn3DdoyOKLjzk0KU=fUwPM4dr98=FatDHktE9_5Fq+g@mail.gmail.com>
Subject: Re: [PATCH v2] xfs: preserve i_rdev when recycling a reclaimable inode
Content-Type: text/plain; charset="UTF-8"
Sender: linux-xfs-owner@vger.kernel.org
List-ID: <linux-xfs.vger.kernel.org>
List-Id: xfs
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>, Eryu Guan <eguan@redhat.com>, Miklos Szeredi <miklos@szeredi.hu>, linux-xfs <linux-xfs@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Greg KH <gregkh@linuxfoundation.org>, stable <stable@vger.kernel.org>

On Thu, Feb 1, 2018 at 2:27 AM, Amir Goldstein <amir73il@gmail.com> wrote:
> On Mon, Jan 29, 2018 at 5:50 PM, Darrick J. Wong
> <darrick.wong@oracle.com> wrote:
>> On Mon, Jan 29, 2018 at 01:07:36PM +0200, Amir Goldstein wrote:
>>> On Fri, Jan 26, 2018 at 11:44 PM, Darrick J. Wong
>>> <darrick.wong@oracle.com> wrote:
>>> > On Fri, Jan 26, 2018 at 09:44:29AM +0200, Amir Goldstein wrote:
>>> >> Commit 66f364649d870 ("xfs: remove if_rdev") moved storing of rdev
>>> >> value for special inodes to VFS inodes, but forgot to preserve the
>>> >> value of i_rdev when recycling a reclaimable xfs_inode.
>>> >>
>>> >> This was detected by xfstest overlay/017 with inodex=on mount option
>>> >> and xfs base fs. The test does a lookup of overlay chardev and blockdev
>>> >> right after drop caches.
>>> >>
>>> >> Overlayfs inodes hold a reference on underlying xfs inodes when mount
>>> >> option index=on is configured. If drop caches reclaim xfs inodes, before
>>> >> it relclaims overlayfs inodes, that can sometimes leave a reclaimable xfs
>>> >> inode and that test hits that case quite often.
>>> >>
>>> >> When that happens, the xfs inode cache remains broken (zere i_rdev)
>>> >> until the next cycle mount or drop caches.
>>> >>
>>> >> Fixes: 66f364649d870 ("xfs: remove if_rdev")
>>> >> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
>>> >
>>> > Looks ok,
>>> > Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
>>> >
>>>
>>> I recon that now we should now also strap:
>>> Cc: <stable@vger.kernel.org> #v4.15
>>>
>>> Can I assume, you'll add it on apply?
>>
>> I'll do a proper backport of this and a couple other critical cow
>> fixes after I get the 4.16 stuff merged.
>>
>
> I am not sure what "proper backport" means in the context of
> this patch.
> This is a v4.15-rc1 regression fix that is based on v4.15-rc8.
> It applied cleanly on v4.15.
>
> CC'ing stable for attention.
>
> This patch is now in master, but due to its timing it did not
> get the CC: stable tag.
>

Now really CC stable.

Amir.