linux-ext4 - Re: [PATCH, RFC] Ext3: Mount partition as read only if during orphan cleanup truncate fails to obtain journal handle.

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Message-ID: <CAOiN93=p-EOiRWOs=mw52zkQtFy=6Tg7PgJ7HT=drcgFKWCNdw@mail.gmail.com>
Date:	Mon, 29 Oct 2012 16:37:17 +0530
From:	Ashish Sangwan <ashishsangwan2@...il.com>
To:	Jan Kara <jack@...e.cz>
Cc:	linux-ext4@...r.kernel.org,
	Ashish Sangwan <ashish.sangwan2@...il.com>,
	Namjae Jeon <linkinjeon@...il.com>
Subject: Re: [PATCH, RFC] Ext3: Mount partition as read only if during orphan
 cleanup truncate fails to obtain journal handle.

On Mon, Oct 29, 2012 at 4:19 PM, Jan Kara <jack@...e.cz> wrote:
> On Wed 24-10-12 16:12:44, Ashish Sangwan wrote:
>> During orphan cleanup while doing truncate, if we fail to obtain journal
>> handle, the inode for which truncate was called would not be removed from
>> both the on-disk and in-memory orphan lists as the call to ext3_orphan_del
>> would not be executed.
>>
>> This would have following consequences:
>> a) As the inode is not removed from the on-disk list, truncate would be
>> called again for the same inode. Each call would add the inode to the
>> in-memory list. This operation would continue endlessly or until truncate
>> is succeed.
>>
>> b) If somehow, after some iterations, truncate is succeed, ext3_orphan_del
>> will only remove the inode from in-memory list just 1 time. This will trigger
>> j_assert during put super.
>>
>> This patch handles both the problems. If truncate fails, first in-memory
>> list is cleared and than the partition is mounted as read only.
>> Failure to obtain journal handle during mount may suggest that journal
>> device is corrupted.
>   Could you really trigger any of the described bugs? Because
> ext3_truncate() does take care to remove inode from orphan list even if
> starting of a transaction fails (see out_notrans label in ext3_truncate()).
Sorry, my bad. Did'nt notice out_notrans tag.
Actually, its just ext4 which does not clear orphan list.
Please ignore this patch.

Thanks,
Ashish
> Also spitting additional messages should be unnecessary - the error which
> caused truncate to fail should have logged the error message and also taken
> appropriate action depending on filesystem configuration (i.e., remount fs
> read-only, panic the system, or do nothing).
>
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