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

[Christian Zangl <coralllama@gmail.com>]

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>?
...

> If you can rollback, would you provide the ext4 fs image?

You mean the vmdk from VMware? I do have a backup.

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
>