Re: testing result of loop-aio patchset on ext3

Rui Xiang
2014-07-21T02:35:11Z

On 2014/7/18 17:10, Lukáš Czerner wrote:
> On Wed, 16 Jul 2014, Rui Xiang wrote:
>
>> Date: Wed, 16 Jul 2014 17:28:10 +0800
>> From: Rui Xiang <rui.xiang@huawei.com>
>> To: Lukáš Czerner <lczerner@redhat.com>
>> Cc: Dave Kleikamp <dave.kleikamp@oracle.com>, linux-ext4@vger.kernel.org,
>> linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
>> Li Zefan <lizefan@huawei.com>
>> Subject: Re: testing result of loop-aio patchset on ext3
>>
>> On 2014/7/16 15:58, Lukáš Czerner wrote:
>>> On Wed, 16 Jul 2014, Rui Xiang wrote:
>>>
>>>> Date: Wed, 16 Jul 2014 11:54:24 +0800
>>>> From: Rui Xiang <rui.xiang@huawei.com>
>>>> To: Lukáš Czerner <lczerner@redhat.com>
>>>> Cc: Dave Kleikamp <dave.kleikamp@oracle.com>, linux-ext4@vger.kernel.org,
>>>> linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
>>>> Li Zefan <lizefan@huawei.com>
>>>> Subject: Re: testing result of loop-aio patchset on ext3
>>>>
>>>> On 2014/7/14 17:51, Lukáš Czerner wrote:
>>>>> On Mon, 14 Jul 2014, Rui Xiang wrote:
>>>>>
>>>>>> Date: Mon, 14 Jul 2014 17:34:38 +0800
>>>>>> From: Rui Xiang <rui.xiang@huawei.com>
>>>>>> To: Dave Kleikamp <dave.kleikamp@oracle.com>, linux-ext4@vger.kernel.org
>>>>>> Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
>>>>>> Li Zefan <lizefan@huawei.com>
>>>>>> Subject: testing result of loop-aio patchset on ext3
>>>>>>
>>>>>> Hi Dave,
>>>>>>
>>>>>> We export a container image file as a block device via loop device, but we
>>>>>> found it's very easy that the container rootfs gets corrupted due to power
>>>>>> loss.
>>>>>>
>>>>>> Your early version of loop-aio patchset said the patchset can make loop
>>>>>> mounted filesystems recoverable(lkml.org/lkml/2012/3/30/317), but we found
>>>>>> it doesn't help.
>>>>>>
>>>>>> Both the guest fs and host fs are ext3.
>>>>>>
>>>>>> The loop-aio patchset is from:
>>>>>> git://github.com/kleikamp/linux-shaggy.git aio_loop
>>>>>>
>>>>>> Steps:
>>>>>> 1. dd a 10G image, mkfs.ext3,
>>>>>> # dd if=/dev/zero of=./raw_image bs=1M count=10000
>>>>>> # echo y | mkfs.ext3 raw_image
>>>>>>
>>>>>> 2. losetup a loop device, mount at ./test_dir
>>>>>> # losetup /dev/loop1 raw_image
>>>>>> # mount /dev/loop1 ./test_dir
>>>>>>
>>>>>> 3. copy fs_mark into test_dir and run
>>>>>> # ./fs_mark -d ./tmp/ -s 102400000 -n 80
>>>>>>
>>>>>> 4. during runing fs_mark, make systerm reboot indirectly.
>>>>>> # echo b > /proc/sysrq-trigger
>>>>>>
>>>>>> After systerm booted up, sometimes fsck reported raw_image fs has been damaged.
>>>>>>
>>>>>> # fsck.ext3 -n raw_image
>>>>>> e2fsck 1.41.9 (22-Aug-2009)
>>>>>> Warning: skipping journal recovery because doing a read-only filesystem check.
>>>>>> raw_image contains a file system with errors, check forced.
>>>>>> Pass 1: Checking inodes, blocks, and sizes
>>>>>> Pass 2: Checking directory structure
>>>>>> Pass 3: Checking directory connectivity
>>>>>> Pass 4: Checking reference counts
>>>>>> Pass 5: Checking group summary information
>>>>>> Free blocks count wrong (2481348, counted=2480577).
>>>>>> Fix? no
>>>>>> Free inodes count wrong (640837, counted=640835).
>>>>>> Fix? no
>>>>>> raw_image: ********** WARNING: Filesystem still has errors **********
>>>>>> raw_image: 11/640848 files (0.0% non-contiguous), 78652/2560000 blocks
>>>>>
>>>>> It's not damaged, this is expected result if you're using old
>>>>> e2fsprogs which still treats this as an error.
>>>>>
>>>>> It's not an error because we only update superblock summary at
>>>>> unmount time so with unclean shutdown it's likely that it does not
>>>>> match the reality, but e2fsck can and will easily fix that for you.
>>>>>
>>>>> Please try e2fsprogs v1.42.3 or newer.
>>>>>
>>>>
>>>> Hi Lukas,
>>>>
>>>> I updated e2fsprogs to v1.42.3, and user the newer fsck.ext3 to check raw_image.
>>>> Exactly, the result seemed normal.
>>>
>>> Now I can see that there are much more problems than before, that's
>>> weird. Sorry for not making this clear, but for this kind of
>>> reproducers please use the most recent e2fsprogs. Also , what is the
>>> kernel version you're using in this test ?
>>>
>>
>> I use the most recent e2fsprogs 1.42.11 to check, and the error info is same as
>> result fscked by v1.42.3. It seems that shouldn't be the reason.
>>
>> Otherwise, the kernel version in this test is stable 3.4.
>
> In that case, this is a problem somewhere else. I'll try to
> reproduce and see what I can see.
>
> I assume you're not able to reproduce this on a real device ?
>

Yes, it only exits on a loop device in my test.

Otherwise, There was another case in this test:

I fsck the err image with "-n", the result contains 7 issues.

# fsck.ext3 -n image1
Warning: skipping journal recovery because doing a read-only filesystem check.
image1 has been mounted 36 times without being checked, check forced.
Pass 1: Checking inodes, blocks, and sizes
*Inode 16407, i_size is 643005, should be 647168. Fix? no
*Inode 16407, i_blocks is 1264, should be 1272. Fix? no
*Inode 409941, i_blocks is 200208, should be 16688. Fix? no
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
*Block bitmap differences: -1643951 +1644741 -(1646592--1646598) +(1648640--1648646) -(1657079--1658102) -(1658104--1659127) -(1659129--1660152) -(1660154--1661177) -(1661179--1662202) -(1662204--1663227) -(1663229--1664252) -(1664254--1665277) -(1665279--1666302) -(1666304--1667327) -(1667329--1668352) -(1668354--1669377) -(1669379--1670402) -(1670404--1671167) -(1671688--1671947) -(1671949--1672972) -(1672974--1673997) -(1673999--1675022) -(1675024--1676047) -(1676049--1677072) -(1677074--1678097) -(1678099--1679122) -(1679124--1680147) -(1680149--1680560)
Fix? no
*Free blocks count wrong for group #2 (31522, counted=31520).
Fix? no
*Free blocks count wrong for group #43 (15870, counted=15871).
Fix? no
*Free blocks count wrong for group #45 (398, counted=396).
Fix? no
*Free blocks count wrong (2203971, counted=2203968).
Fix? no
image1: ********** WARNING: Filesystem still has errors **********
image1: 13008/655360 files (0.3% non-contiguous), 417469/2621440 blocks

When I "fsck -y" the image, it seems that only fixes 1 issue.

# fsck.ext3 -y image1
image1: recovering journal
image1 has been mounted 36 times without being checked, check forced.
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
*Free blocks count wrong (2203971, counted=2203968).
Fix<y>? yes
image1: ***** FILE SYSTEM WAS MODIFIED *****
image1: 13008/655360 files (0.3% non-contiguous), 417472/2621440 blocks

So, I assume journal is revocered before fs checking while doing
"fsck -y", and other issues are fixed during fs revovering journal,
is that?

Thanks!

> Thanks!
> -Lukas
>
>>
>>
>> Thanks!
>>
>>> Thanks!
>>> -Lukas
>>>
>>>>
>>>> Then, I continue my previous test. And after testing 35 times, "fsck -n" reported image fs
>>>> had been damaged, too.
>>>>
>>>> # fsck.ext3 -n image1
>>>> e2fsck 1.42.3.wc1 (28-May-2012)
>>>> Warning: skipping journal recovery because doing a read-only filesystem check.
>>>> image1 has been mounted 36 times without being checked, check forced.
>>>> Pass 1: Checking inodes, blocks, and sizes
>>>> Inode 16407, i_size is 597447, should be 602112. Fix? no
>>>> Inode 16407, i_blocks is 1176, should be 1184. Fix? no
>>>> Inode 409941, i_blocks is 200208, should be 112. Fix? no
>>>> Pass 2: Checking directory structure
>>>> Pass 3: Checking directory connectivity
>>>> Pass 4: Checking reference counts
>>>> Pass 5: Checking group summary information
>>>> Block bitmap differences: -1506836 -1506843 -(1506859--1506860) -(1660941--1661964) -(1661966--1671167) -(1671688--1686473)
>>>> Fix? no
>>>> Free blocks count wrong for group #2 (31558, counted=31556).
>>>> Fix? no
>>>> Free blocks count wrong for group #43 (15871, counted=15867).
>>>> Fix? no
>>>> Free blocks count wrong (2204041, counted=2204035).
>>>> Fix? no
>>>> image1: ********** WARNING: Filesystem still has errors **********
>>>> image1: 13008/655360 files (0.3% non-contiguous), 417399/2621440 blocks
>>>>
>>>> I backup the image to image_bk, and then mount the image to a dir, and cat all files in the image.
>>>> Steps:
>>>> # dd if=image1 of=image_bk
>>>> # mount image1 err_dir
>>>> # find -name '*' -exec cat > /dev/null {} \;
>>>>
>>>> There are no issues during catting, and no err in dmesg too.
>>>>
>>>> *But when I umount the image1 from err_dir, The fsck result didn't show any fs corruption info.
>>>>
>>>> I mount image_bk to err_dir and umount it with no operation directly. The result is same to iamge1.
>>>>
>>>> *So, is fs in the image as a block device via loop device damaged really, or does it have some others issues?
>>>> Could you give me some opinions?
>>>>
>>>>
>>>> Thanks.
>>>>
>>>>
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