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Date: Thu, 12 Feb 2015 18:44:27 +0800
From: Kevin Liao <kevinlia@...il.com>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: Possible file system corruption?
Hi Carlos,
Thank you for the reply. Today I try to run e2fsck again. This time I'm sure
I run it in correct volume. I also try to use different backup suprtblock.
The results are as below:
e2fsck -fnv /dev/md0
e2fsck 1.42.12 (29-Aug-2014)
ext2fs_check_desc: Corrupt group descriptor: bad block for block bitmap
e2fsck: Group descriptors look bad... trying backup blocks...
Corruption found in superblock. (reserved_gdt_blocks = 16384).
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>
e2fsck -fnv -b 8193 /dev/md0
e2fsck 1.42.12 (29-Aug-2014)
e2fsck: Bad magic number in super-block while trying to open /dev/md0
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>
e2fsck -fnv -b 32768 /dev/md0
e2fsck 1.42.12 (29-Aug-2014)
Corruption found in superblock. (reserved_gdt_blocks = 16384).
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>
It all complains about superblock corrupted. I then use dumpe2fs to check the
superblock and get the following:
dumpe2fs -h /dev/md0
dumpe2fs 1.42.12 (29-Aug-2014)
Filesystem volume name: <none>
Last mounted on: /share/MD0_DATA
Filesystem UUID: 6c1f5c4f-7185-436f-bc1f-8876a1d524fe
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: has_journal ext_attr filetype extent 64bit flex_bg
sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: (none)
Filesystem state: clean with errors
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 610230272
Block count: 4881811920
Reserved block count: 218453
Free blocks: 1387940253
Free inodes: 610226921
First block: 0
Block size: 4096
Fragment size: 4096
Group descriptor size: 64
Reserved GDT blocks: 16384
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 4096
Inode blocks per group: 256
RAID stride: 1
Flex block group size: 16
Filesystem created: Mon Jan 13 08:40:19 2014
Last mount time: Thu Feb 12 10:34:24 2015
Last write time: Thu Feb 12 10:35:23 2015
Mount count: 50
Maximum mount count: 31
Last checked: Tue Jun 17 07:54:54 2014
Check interval: 15552000 (6 months)
Next check after: Sun Dec 14 06:54:54 2014
Lifetime writes: 15 TB
Reserved blocks uid: 0 (user unknown)
Reserved blocks gid: 0 (group unknown)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Journal inode: 8
Default directory hash: half_md4
Directory Hash Seed: a9c4f391-d68d-4886-b7cb-5a804077f823
Directory Magic Number: 0x0000
Journal backup: inode blocks
FS Error count: 25
First error time: Thu Jan 1 12:19:59 2015
First error function: ext4_ext_find_extent
First error line #: 400
First error inode #: 95223833
First error block #: 0
Last error time: Wed Feb 4 11:57:05 2015
Last error function: ext4_ext_find_extent
Last error line #: 400
Last error inode #: 95223833
Last error block #: 0
Journal features: journal_incompat_revoke journal_64bit
Journal size: 128M
Journal length: 32768
Journal sequence: 0x00092ac2
Journal start: 0
I can not see anything wrong (except the error count that was what I already
knew). That's why I am really confused about why e2fsck report something like
this.
Kevin
2015-02-10 17:39 GMT+08:00 Carlos Maiolino <cmaiolino@...hat.com>:
> Hello,
>
> I don't work with ext4 for a while, but maybe I can give a few suggestions.
>
> first of all, I'd suggest you to run `e2fsck -fnv` and attach the whole output
> of the command to the e-mail (pastebins are preferred though).
>
> Giving the description, I'd say that you might be trying to run e2fsck in a
> different volume/device that you're actually mounting, but well, that's too soon
> to say.
>
> have you tried to actually run e2fsck specifying a backup superblock?
>
> cheers
>
> On Mon, Feb 09, 2015 at 07:33:28PM +0800, Kevin Liao wrote:
>> Hi All,
>>
>> Recently whenvevr I try to access one file, I saw the following kernel log:
>>
>> "EXT4-fs error (device md0): ext4_ext_find_extent:400: inode #95223833: comm
>> fio: bad header/extent: invalid magic - magic e2b6, entries 59156, max
>> 58100(0), depth 43399(0)"
>>
>> inode 95223833 is just the file I want to read. I guess there may be some
>> corruption in the file system. Therefore I umount it and run e2fsck command
>> but get the following result:
>>
>> "ext2fs_check_desc: Corrupt group descriptor: bad block for block bitmap
>> ./e2fsck: Group descriptors look bad... trying backup blocks...
>> Corruption found in superblock. (reserved_gdt_blocks = 16384).
>>
>> The superblock could not be read or does not describe a valid ext2/ext3/ext4
>> filesystem. If the device is valid and it really contains an ext2/ext3/ext4
>> filesystem (and not swap or ufs or something else), then the superblock
>> is corrupt, and you might try running e2fsck with an alternate superblock:
>> e2fsck -b 8193 <device>
>> or
>> e2fsck -b 32768 <device>"
>>
>> It seems that the superblock is bad, however I can still mount it and access
>> to other files without error. The kernel version is 3.4.23. Is there anything
>> I can do to recover the file? Any help is very appreciated. Thank a lot.
>>
>> Kevin
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>
> --
> Carlos
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