From: Colin Ian King <colin.king@canonical.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
overlayfs <linux-unionfs@vger.kernel.org>,
kernel-janitors@vger.kernel.org,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ovl: create UUIDs for file systems that do not set the superblock UUID
Date: Thu, 7 Nov 2019 09:43:59 +0000 [thread overview]
Message-ID: <bba96a64-a9f7-cd03-e00b-8ee369520ae7@canonical.com> (raw)
In-Reply-To: <f88a4ef7-3e2a-9e17-1573-3594288091cd@canonical.com>
On 07/11/2019 09:12, Colin Ian King wrote:
> On 07/11/2019 08:45, Colin Ian King wrote:
>> On 07/11/2019 07:08, Amir Goldstein wrote:
>>> On Thu, Nov 7, 2019 at 1:43 AM Colin King <colin.king@canonical.com> wrote:
>>>>
>>>> From: Colin Ian King <colin.king@canonical.com>
>>>>
>>>> Some file systems such as squashfs do not set the UUID in the
>>>> superblock resulting in a zero'd UUID. In cases were two or more
>>>> of these file systems are overlayed on the lower layer we can hit
>>>> overlay corruption issues because identical zero'd overlayfs UUIDs
>>>> are impossible to differentiate between. This can be fixed by
>>>> creating an overlayfs UUID based on the file system from the
>>>> superblock s_magic and s_dev fields. (This currently seems like
>>>> enough information to be able create a UUID, but the could be
>>>> scope to use other super block fields such as the pointer s_fs_info
>>>> but may need some obfuscation).
>>>>
>>>
>>> The fix is incorrent. uuid stored in xattr needs to have persistent properties.
>>> In the use case that you describe, the origin file handle should simply be
>>> ignored.
>>>
>>> Please test attached patch.
>>
>> Thanks for the patch. Tested, and the error still occurs:
>>
>> [ 163.959633] overlayfs: invalid origin (etc/.pwd.lock, ftype=8000,
>> origin ftype=4000).
>
> Added debug, seems like nouuid is not being set to true, nouuid is false
> on the layers 0 and 1.
So nouuid is not being set in ovl_lower_uuid_ok() because the code is
returning early because of the following statement:
if (!ofs->config.nfs_export && !(ofs->config.index && ofs->upper_mnt))
return true;
..and not getting to the following for-loop.
>
>>
>> Colin
>>
>>>
>>> Thanks,
>>> Amir.
>>>
>>
>
next prev parent reply other threads:[~2019-11-07 9:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 23:43 [PATCH] ovl: create UUIDs for file systems that do not set the superblock UUID Colin King
2019-11-07 7:08 ` Amir Goldstein
2019-11-07 7:18 ` Dan Carpenter
2019-11-07 8:45 ` Colin Ian King
2019-11-07 9:12 ` Colin Ian King
2019-11-07 9:43 ` Colin Ian King [this message]
2019-11-07 9:56 ` Amir Goldstein
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