linux-ext4 - Re: [PATCH, RFC] Ext4: Mount partition as read only if during orphan cleanup truncate fails to obtain journal handle.

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Date:	Thu, 6 Dec 2012 16:59:43 +0530
From:	Ashish Sangwan <ashishsangwan2@...il.com>
To:	Namjae Jeon <linkinjeon@...il.com>
Cc:	"Theodore Ts'o" <tytso@....edu>,
	ext4 development <linux-ext4@...r.kernel.org>,
	Ashish Sangwan <ashish.sangwan2@...il.com>,
	Lukáš Czerner <lczerner@...hat.com>,
	Eric Sandeen <sandeen@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH, RFC] Ext4: Mount partition as read only if during orphan
 cleanup truncate fails to obtain journal handle.

Hi Ted,

Did you get any time to look into this patch?
This problem is with ext4 only as ext4_truncate does not clean the
orphan list unlike that of ext3_truncate.
Instead, in case of failure to obtain handle, orphan list cleanup is
done in ext4_setattr.
But during mount, ext4_truncate is not called via ext4_setattr and
hence the problem.
What do you think?

On Fri, Oct 26, 2012 at 5:11 PM, Namjae Jeon <linkinjeon@...il.com> wrote:
> Add Cc in mail loop.
>
> Thanks.
>
> 2012/10/24, Ashish Sangwan <ashishsangwan2@...il.com>:
>> 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 ext4_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, ext4_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.
>>
>> Signed-off-by: Ashish Sangwan <ashish.sangwan2@...il.com>
>> Signed-off-by: Namjae Jeon <linkinjeon@...il.com>
>> ---
>>  fs/ext4/super.c | 16 +++++++++++++++-
>>  1 file changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>> index 4e2aacb..859eccb 100644
>> --- a/fs/ext4/super.c
>> +++ b/fs/ext4/super.c
>> @@ -2201,7 +2201,21 @@ static void ext4_orphan_cleanup(struct super_block
>> *sb,
>>                       jbd_debug(2, "truncating inode %lu to %lld bytes\n",
>>                                 inode->i_ino, inode->i_size);
>>                       ext4_truncate(inode);
>> -                     nr_truncates++;
>> +                     if (list_empty(&EXT4_I(inode)->i_orphan)) {
>> +                             nr_truncates++;
>> +                     } else {
>> +                             /* Remove inode from in-memory orphan list */
>> +                             list_del_init(&EXT4_I(inode)->i_orphan);
>> +                             ext4_msg(sb, KERN_ERR, "Truncate failed for "
>> +                                      "orphan  inode = %lu. Running e2fsck"
>> +                                      " is recommended", inode->i_ino);
>> +                             if (!(s_flags & MS_RDONLY)) {
>> +                                     ext4_msg(sb, KERN_INFO, "FS would be"
>> +                                             " mounted as readonly");
>> +                                     s_flags |= MS_RDONLY;
>> +                             }
>> +                             break;
>> +                     }
>>               } else {
>>                       ext4_msg(sb, KERN_DEBUG,
>>                               "%s: deleting unreferenced inode %lu",
>> --
>> 1.7.11.4
>>
>>
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