Re: "missing data block" when converting ext4 to btrfs

[Christian Zangl <coralllama@gmail.com>]

On 2020-07-14 12:10, Qu Wenruo wrote:
> 
> 
> On 2020/7/14 下午5:33, Christian Zangl wrote:
>> On 2020-07-14 10:09, Qu Wenruo wrote:
>>>
>>>
>>> On 2020/7/14 下午3:58, Christian Zangl wrote:
>>>> On 2020-07-14 08:10, Qu Wenruo wrote:
>>>>>
>>>>>
>>>>> On 2020/7/14 上午3:46, Christian Zangl wrote:
>>>>>> I am on a test VM where I am trying to convert a second disk to btrfs.
>>>>>>
>>>>>> The conversion fails with the error missing data block for bytenr
>>>>>> 1048576 (see below).
>>>>>>
>>>>>> I couldn't find any information about the error. What can I do to fix
>>>>>> this?
>>>>>>
>>>>>> $ fsck -f /dev/sdb1
>>>>>> fsck from util-linux 2.35.2
>>>>>> e2fsck 1.45.6 (20-Mar-2020)
>>>>>> 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
>>>>>> /dev/sdb1: 150510/4194304 files (0.5% non-contiguous),
>>>>>> 2726652/16777216
>>>>>> blocks
>>>>>>
>>>>>> $ btrfs-convert /dev/sdb1
>>>>>> create btrfs filesystem:
>>>>>>            blocksize: 4096
>>>>>>            nodesize:  16384
>>>>>>            features:  extref, skinny-metadata (default)
>>>>>>            checksum:  crc32c
>>>>>> creating ext2 image file
>>>>>> ERROR: missing data block for bytenr 1048576
>>>>>> ERROR: failed to create ext2_saved/image: -2
>>>>>> WARNING: an error occurred during conversion, filesystem is partially
>>>>>> created but not finalized and not mountable
>>>>>
>>>>> Can btrfs-convert -r rollback the fs?
>>>>
>>>> No:
>>>>
>>>> $ sudo btrfs-convert -r /dev/sdb1
>>>> No valid Btrfs found on /dev/sdb1
>>>> ERROR: unable to open ctree
>>>> ERROR: rollback failed
>>>>
>>>> If I do `fsck -f /dev/sdb1` I get lots of errors:
>>>>
>>>> t-arch:~$ sudo fsck -f /dev/sdb1
>>>> fsck from util-linux 2.35.2
>>>> e2fsck 1.45.6 (20-Mar-2020)
>>>> Resize inode not valid.  Recreate<y>? yes
>>>> Pass 1: Checking inodes, blocks, and sizes
>>>> Deleted inode 3681 has zero dtime.  Fix<y>? yes
>>>> Inodes that were part of a corrupted orphan linked list found.
>>>> Fix<y>? yes
>>>> Inode 3744 was part of the orphaned inode list.  FIXED.
>>>> Deleted inode 3745 has zero dtime.  Fix<y>? yes
>>>> Inode 3747 has INLINE_DATA_FL flag on filesystem without inline data
>>>> support.
>>>> Clear<y>? yes
>>>> Inode 3748 was part of the orphaned inode list.  FIXED.
>>>> Inode 3748 has a extra size (6144) which is invalid
>>>> Fix<y>? yes
>>>> Inode 3751 is in use, but has dtime set.  Fix<y>? yes
>>>> Inode 3751 has imagic flag set.  Clear<y>? yes
>>>> Inode 3752 was part of the orphaned inode list.  FIXED.
>>>> Inode 3753 was part of the orphaned inode list.  FIXED.
>>>> Inode 3754 is in use, but has dtime set.  Fix<y>? yes
>>>> Inode 3755 was part of the orphaned inode list.  FIXED.
>>>> Inode 3755 has imagic flag set.  Clear ('a' enables 'yes' to all)
>>>> <y>? yes
>>>> Deleted inode 3801 has zero dtime.  Fix ('a' enables 'yes' to all) <y>?
>>>> ...
>>>
>>> This sounds like the cause.
>>>
>>> As btrfs completely rely on the used space reported from ext*, and if
>>> the fs is corrupted, then a lot of things can go wrong.
>>
>> No, maybe you missed it but I did a fsck before the convert (see above).
>> It reported no errors.
>>
>> Only after the failed btrfs-convert I get the errors.
>>
>>
>>>>
>>>>> If you can rollback, would you provide the ext4 fs image?
>>>>
>>>> You mean the vmdk from VMware? I do have a backup.
>>>
>>> Would you mind to run e2fsck on the backup first to see if that's the
>>> problem?
>>
>> The backup has no fsck issues.
>>
>>> If the fixed fs can not pass btrfs-convert still, would you mind to send
>>> the fs image?
>>
>> How/where would you like me to send it?
> 
> Does Google driver work for you?

I sent it to you.

Thanks, Christian

> Thanks,
> Qu
>>
>> Thanks, Christian
>>
>>>
>>> Thanks,
>>> Qu
>>>
>>>>
>>>> Thanks!
>>>>
>>>> Christian
>>>>
>>>>>
>>>>> Thanks,
>>>>> Qu
>>>>>
>>>>>>
>>>>>> $ uname -a
>>>>>> Linux t-arch 5.7.7-arch1-1 #1 SMP PREEMPT Wed, 01 Jul 2020 14:53:16
>>>>>> +0000 x86_64 GNU/Linux
>>>>>>
>>>>>> $ btrfs --version
>>>>>> btrfs-progs v5.7
>>>>>
>>>>
>>>
>>
>