Message-ID: <CA+qGm=-wZz1ZzTSxZ1U-7QkqFu-t9j=3BZZz+MFpZ=yL8=ec7w@mail.gmail.com>
Date:	Fri, 13 Sep 2013 13:33:12 +0000
From:	Alexander Harrowell <a.harrowell@...il.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: Fwd: Fwd: strange e2fsck magic number behaviour

Hmm, coming back to this, block 16777215 with identical content is
recurring at intervals of 8 inodes.

On Fri, Sep 13, 2013 at 11:46 AM, Alexander Harrowell
<a.harrowell@...il.com> wrote:
> To update, I've found that a) even with 8GB RAM and 8GB swap, e2fsck
> can silently run out of memory.
>
> b) something is clearly wrong in block 16777215.
>
> c) debugfs places that block in inode 409774, in use, with an extent
> of 16777212-5 and 10 associated filenames, plus several dozen ext2
> directory errors.
>
> d) after a first attempt with the updated (1.42.8) version of
> e2fsprogs this morning, the disk is mountable again but not much on it
> is accessible and the % usage is still screwy.
>
> e) that said, "new" debugfs and e2fsck seem to find more things to fix.
>
> f) trying to decrypt the filenames, most of them don't get found by
> ecryptfs-find but the first one produces a list of the files in /home/
> and a lot of find: no such file or directory messages.
>
> g) dumpe2fs -b reports no bad blocks. smart reports drive in good condition.
>
> h) I'm quite tempted to zap 409774.
>
> On Thu, Sep 12, 2013 at 7:33 PM, Alexander Harrowell
> <a.harrowell@...il.com> wrote:
>> investigating dmesg, I think e2fsck may have been running out of memory.
>>
>> On Thu, Sep 12, 2013 at 6:59 PM, Eric Sandeen <sandeen@...hat.com> wrote:
>>> On 9/12/13 11:56 AM, Alexander Harrowell wrote:
>>>> ---------- Forwarded message ----------
>>>> From: Alexander Harrowell <a.harrowell@...il.com>
>>>> Date: Thu, Sep 12, 2013 at 4:54 PM
>>>> Subject: Re: Fwd: strange e2fsck magic number behaviour
>>>> To: Eric Sandeen <sandeen@...hat.com>
>>>>
>>>>
>>>> It was 63GB and I just wanted to fork over 3GB of extra space from my
>>>> Windows partition...
>>>
>>> Ok, so you tried to resize from 63G to 66G?  Should have been relatively
>>> easy/safe.  I forgot to ask which version of e2fsprogs you had, but if
>>> you did the grow online/mounted, most of the work is done in the kernel.
>>>
>>> As Ted said, knowing more info might yield clues:
>>>
>>> 1) what e2fsprogs version?
>>> 2) what were the kernel messages when it crashed/hung?
>>> 3) what was the fsck output?
>>>
>>> If you didn't save that stuff, it makes it harder to do a post-mortem...
>>>
>>>> The fstab is as follows
>>>>
>>>> /dev/sda1 SYSTEM_DRV ntfs 1.17g (boot)
>>>> /dev/sda2 Windows7_OS ntfs 63.4G
>>>> /dev/sda4 extended partition containing:
>>>> -- /dev/sda6 swap linux-swap 8.05G
>>>> -- /dev/sda5 /home ext4 66.14G
>>>> /dev/sda3 Lenovo_Recovery ntfs 10.25G
>>>> unallocated 1M
>>>>
>>>> that's what was intended and is what gparted reports. (however,
>>>> weirdly, if you ask Ubuntu Disk Utility, it says /dev/sda5 is 71GB and
>>>> /dev/sda4 is correspondingly bigger. this I have only just noticed.)
>>>
>>> TBH, I have no idea what Ubuntu Disk Utility does.  I'd trust fdisk -lu
>>> output or /proc/partitions for accurate size info.
>>>
>>> Oh; 61.14GiB (powers of 2) == 71 GB (powers of 10)
>>>
>>> (61.14*1024*1024*1024/1000/1000/1000 = 71)
>>>
>>> So Ubuntu Disk Utility is in cahoots w/ the drive manufacturers, and
>>> using more favorable units.  ;)
>>>
>>> -Eric
>>>
>>>> kernel is 3.2.0-29-generic, machine is a ThinkPad X200s with 160GB disk.
>>>>
>>>> thanks for your help.
>>>>
>>>>
>>>> On Thu, Sep 12, 2013 at 4:44 PM, Eric Sandeen <sandeen@...hat.com> wrote:
>>>>> On 9/12/13 11:39 AM, Alexander Harrowell wrote:
>>>>>> I'm currently trying to recover an ext4 filesystem. Last night, during
>>>>>> a resize operation,
>>>>>
>>>>> from what size to what size? On what kernel?
>>>>>
>>>>>> the system (Ubuntu 12.04 LTS on my fix-stuff usb
>>>>>> stick) locked up hard and eventually crashed. Restarting,
>>>>>> unsurprisingly, gparted offered to check the volume. e2fsck, called
>>>>>> from within gparted, replayed the journal overnight and completed the
>>>>>> resize.
>>>>>
>>>>> hmmm... perhaps.
>>>>>
>>>>>> however, where I was expecting a volume with about 3.5GB of free
>>>>>> space, there was now a volume with 32GB free space, a bit more than
>>>>>> 50% utilised. inevitably, trying to boot the linux that lives in there
>>>>>> dropped into grub rescue.
>>>>>>
>>>>>> going back, I tried to e2fsck it. this reported large numbers of inode
>>>>>> issues and eventually reported clean. I could mount the volume, but
>>>>>> file metadata looked generally broken (lots of ?s). testdisk showed
>>>>>> the partitions were intact, although it claimed the drive was the
>>>>>> wrong size (incorrectly), and found lots of deleted files within my
>>>>>> ecryptfs home folder. It also found the backup superblocks for the
>>>>>> damaged volume.
>>>>>>
>>>>>> the first couple I tried were corrupt, but the third was valid. e2fsck
>>>>>> -b [superblock] -y reports fixing a lot of inode things, checksums,
>>>>>> and then restarts.  it then starts to report hunormous numbers of
>>>>>> multiply-claimed blocks.
>>>>>>
>>>>>> and now comes the interesting bit - at some point, block 16777215
>>>>>> starts to appear more and more often in the inodes, often duplicated,
>>>>>> until it starts to print out the number 16777215 in a fast loop. in
>>>>>> fact, it looks like it hits some inode and keeps printing block
>>>>>> 16777215 to the same very long line (it's generated 500MB of log)
>>>>>
>>>>> = 111111111111111111111111 binary.
>>>>>
>>>>> Guessing it's maybe a bitmap block?
>>>>>
>>>>> Resize2fs has had a lot of trouble lately it seems.  You may have just
>>>>> been the unlucky recipient of a resize2fs bug...
>>>>>
>>>>> -Eric
>>>>>
>>>>>> I removed the first inode containing this block via debugfs, without
>>>>>> this helping.
>>>>>>
>>>>>> It sticks out that 16777215 is a magic number (the maximum in a 48 bit
>>>>>> address space) and I google that either ext4 or e2fsck has had a bug
>>>>>> involving it before.
>>>>>> --
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>>>>>
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>>>
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