From: Kevin Liao <kevinlia@gmail.com>
Subject: Possible file system corruption?
Date: Mon, 9 Feb 2015 19:33:28 +0800
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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