Date:   Tue, 22 May 2018 08:31:09 +0200
From:   Jaco Kroon <jaco@....co.za>
To:     linux-ext4 <linux-ext4@...r.kernel.org>
Cc:     Pieter Kruger <pieter@....co.za>, Theodore Ts'o <tytso@....edu>
Subject: Re: corrupt filesystem, superblock/journal - fsck

Hi All,

Is there any additional information required here that would help to assist?

/ on the filesystem (mounted on /home) is returning empty directory
listings, and fsck (1.43.6) is not fixing the problem.  I've checked the
changelogs for fsck since and in spite of updating to 1.43.9 the
bahaviour persists.

The changelog entries from 1.43.8 that I thought might relate:

Fix a potential use after free bug in e2fsck when fixing a corrupted
root node in directory hash tree.

Fix a bug in e2fsck where a badly/maliciously corrupted superblock
(which is not fixed due to the -n option, for example) can cause a
floating point exception when printing the summary statistics.
(Addresses Debian Bug: #879220)

The former looked potential, the latter looks like a crash type scenario
which we're not seeing.

Kind Regards,
Jaco



On 21/05/2018 14:21, Jaco Kroon wrote:
> Hi All,
>
> We had a host starting to fail processing on an ext4 filesystem directly
> after extend from 60.5TB to 64TB (lvresize -L64T /dev/lvm/home,
> resize2fs /dev/lvm/home).
>
> We rebooted, and now the filesystem will mount but the problem
> persists.  We've now umounted the filesystem, and fsck complains as follows:
>
> crowsnest ~ # fsck.ext4 -f /dev/lvm/home
> e2fsck 1.43.6 (29-Aug-2017)
> Superblock has an invalid journal (inode 8).
> Clear<y>? yes
> *** journal has been deleted ***
>
> Corruption found in superblock.  (inodes_count = 0).
>
> 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>
>
> Corruption found in superblock.  (first_ino = 11).
>
> 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>
>
> Inode count in superblock is 0, should be 4294967295.
> Fix<y>? yes
>
> /dev/lvm/home: ***** FILE SYSTEM WAS MODIFIED *****
>
> Note that in spite of supposedly fixing the errors if we re-run fsck the
> exact errors repeat.  Even if we use -b 32768 (4K blocks) it still repeats.
>
> crowsnest ~ # dumpe2fs -f /dev/lvm/home
> dumpe2fs 1.43.6 (29-Aug-2017)
> Filesystem volume name:   <none>
> Last mounted on:          /home
> Filesystem UUID:          9f0e94bc-25b7-44b7-afdd-bfaa90dbf25c
> Filesystem magic number:  0xEF53
> Filesystem revision #:    1 (dynamic)
> Filesystem features:      has_journal ext_attr dir_index filetype
> meta_bg extent 64bit flex_bg sparse_super large_file huge_file uninit_bg
> dir_nlink extra_isize
> Filesystem flags:         signed_directory_hash
> Default mount options:    user_xattr acl
> Filesystem state:         clean with errors
> Errors behavior:          Continue
> Filesystem OS type:       Linux
> Inode count:              0
> Block count:              17179869184
> Reserved block count:     0
> Free blocks:              997705247
> Free inodes:              4176704883
> First block:              0
> Block size:               4096
> Fragment size:            4096
> Group descriptor size:    64
> Blocks per group:         32768
> Fragments per group:      32768
> Inodes per group:         8192
> Inode blocks per group:   512
> RAID stride:              128
> RAID stripe width:        512
> First meta block group:   1472
> Flex block group size:    16
> Filesystem created:       Tue Feb 10 12:51:13 2015
> Last mount time:          Mon May 21 13:44:11 2018
> Last write time:          Mon May 21 13:44:27 2018
> Mount count:              34
> Maximum mount count:      -1
> Last checked:             Sat Aug 19 19:16:38 2017
> Check interval:           0 (<none>)
> Lifetime writes:          86 TB
> Reserved blocks uid:      0 (user root)
> Reserved blocks gid:      0 (group root)
> 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:      e4a234f2-63e8-4bdd-9591-ba54453485cc
> Journal backup:           inode blocks
> FS Error count:           30230
> First error time:         Mon May 21 12:47:00 2018
> First error function:     ext4_search_dir
> First error line #:       1296
> First error inode #:      304881794
> First error block #:      1219511409
> Last error time:          Mon May 21 13:44:19 2018
> Last error function:      htree_dirblock_to_tree
> Last error line #:        1006
> Last error inode #:       2
> Last error block #:       9697
> dumpe2fs: Illegal inode number while reading journal inode
>
> The filesystem does mount but dmesg gives:
>
> [ 3112.080745] EXT4-fs (dm-5): warning: mounting fs with errors, running
> e2fsck is recommended
> [ 3112.646029] EXT4-fs (dm-5): mounted filesystem with ordered data
> mode. Opts: delalloc,inode_readahead_blks=4096
> [ 3120.230898] EXT4-fs error (device dm-5): htree_dirblock_to_tree:1006:
> inode #2: block 9697: comm ls: bad entry in directory: inode out of
> bounds - offset=0(0), inode=2, rec_len=12, name_len=1
>
> The last line is as soon as we run ls on the mount point (which ends up
> giving an empty, not even . or .., listing).  ls doesn't give nor does
> strace show any errors coming back on any system calls:
>
> stat("/home/", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
> open("/home/", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3
> fstat(3, {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
> getdents(3, /* 0 entries */, 32768)     = 0
> close(3)                                = 0
> close(1)                                = 0
> close(2)                                = 0
>
> Interestingly stat does work:
>
> crowsnest ~ # stat /home
>   File: /home
>   Size: 4096            Blocks: 8          IO Block: 4096   directory
> Device: fd05h/64773d    Inode: 2           Links: 5
> Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
> Access: 2015-03-28 17:36:47.489839898 +0200
> Modify: 2016-12-01 16:52:49.162294603 +0200
> Change: 2016-12-01 16:52:49.162294603 +0200
>  Birth: -
>
> I'm unsure if the filesystem resize completed properly before reboot
> .... and also keeping in mind this is LVM on top of software raid (2 x
> RAID6 arays consisting of 10 and 12 x 4 TB disks respectively), on top
> of an mpt3sas controller.  Kernel 4.16 with the patch at
> https://www.mail-archive.com/linux-scsi@vger.kernel.org/msg72812.html
> applied (which prevents the system from locking up every few days).  As
> far as I can determine this patch series has not been mainlined anywhere
> in 4.16.*.
>
> Kind Regards,
> Jaco
>

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