Re: btrfs-convert aborts with an assert

[Nikolay Borisov <nborisov@suse.com>]

On 6.06.22 г. 17:03 ч., Torbjörn Jansson wrote:
> Hello
> 
> i tried to do a btrfs-convert of a ext4 filesystem and after a short 
> while after starting it i was greeted with:
> 
> # btrfs-convert /dev/xxxx
> btrfs-convert from btrfs-progs v5.16.2
> 
> convert/main.c:1162: do_convert: Assertion `cctx.total_bytes != 0` 
> failed, value 0
> btrfs-convert(+0xffb0)[0x557defdabfb0]
> btrfs-convert(main+0x6c5)[0x557defdaa125]
> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xea)[0x7f66e1f8bd0a]
> btrfs-convert(_start+0x2a)[0x557defdab52a]
> Aborted
> 
> Any idea whats going on?
> Is it a known bug?
> Is the btrfs-progs that come with my dist too old?
> FYI the ext4 filesystem is a bit large ~10tb of used data on it.
> 
> I assume the convert didn't even start in this case and nothing was 
> modified on the ext4 filesystem, correct? or?
> 

This suggests that btrfs progs is unable to properly read/parse the 
superblock of the ext4 filesystem. So you are right that convert hasn't 
even started in this case so your ext4 is intact.

However, that's strange since for ext* related queries we do use libext2fs.