linux-ext4 - Re: [PATCH 03/12] ext4: prevent a fs without journal from being resized

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 18 Jul 2011 11:44:59 +0800
From:	Yongqiang Yang <xiaoqiangnk@...il.com>
To:	Tao Ma <tm@....ma>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 03/12] ext4: prevent a fs without journal from being resized

On Mon, Jul 18, 2011 at 11:28 AM, Yongqiang Yang <xiaoqiangnk@...il.com> wrote:
> On Mon, Jul 18, 2011 at 11:17 AM, Tao Ma <tm@....ma> wrote:
>> On 07/18/2011 10:52 AM, Yongqiang Yang wrote:
>>> This patch prevents a fs without journal from being resized, because
>>> it is easy to detroy the fs.
>> Why you want to do this?  You see any corruption?
>> At least in our product system, no-journal mode is heavily used and we
>> really don't want to disable this feature.
Let's assume a situation without journal.  If the online resizing is
done successfully, it dirties super block and returns, then the added
groups could be used and some data are written to the added groups,
now comes an error before the super block are flushed. Could e2fsck
can find data in the added groups?  If not, this may bring something
strange to users.

It seems that super block should be flushed by online resizing, not
just be dirtied. :-)
Yongqiang.
> I did not see any corruption.  If there is no journal in a fs, then if
> an error happens during online resizing, the filesystem will be
> destroyed easily, I thought.  Just my thought:-)  It needs much more
> feedbacks.
>
> Thanks,
> Yongqiang.
>>
>> Thanks
>> Tao
>>>
>>> Signed-off-by: Yongqiang Yang <xiaoqiangnk@...il.com>
>>> ---
>>>  fs/ext4/resize.c |   10 ++++++++++
>>>  1 files changed, 10 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
>>> index 53d9795..33ab40d 100644
>>> --- a/fs/ext4/resize.c
>>> +++ b/fs/ext4/resize.c
>>> @@ -33,6 +33,16 @@ int ext4_resize_begin(struct super_block *sb)
>>>               return -EPERM;
>>>       }
>>>
>>> +     /*
>>> +      * We are not allowed to do online-resizing on a filesystem without
>>> +      * journal, otherwise, it is easy to destroy the filesystem.
>>> +      */
>>> +     if (!EXT4_SB(sb)->s_journal) {
>>> +             ext4_warning(sb, "There is no journal for the filesystem, "
>>> +                          "so online resizing is not allowed\n");
>>> +             return -EPERM;
>>> +     }
>>> +
>>>       if (test_and_set_bit_lock(EXT4_RESIZING, &EXT4_SB(sb)->s_resize_flags))
>>>               ret = -EBUSY;
>>>
>>
>>
>
>
>
> --
> Best Wishes
> Yongqiang Yang
>



-- 
Best Wishes
Yongqiang Yang
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html