Re: [dm-devel] can't recover ext4 on lvm from ext4_mb_generate_buddy:739: group 1687, 32254 clusters in bitmap, 32258 in gd

[WIMPy <WIMPy@yeti.dk>]

... and another update:

> As there was a mention at the beginning that this may have happened after an 
> upgrade from 3.1.5 to 3.2, I will build a 3.1.5 and see if that really makes 
a 
> difference.

Yes it does.
3.1.5 has been working for 4.5 hours now, continuing form the point where 3.2 
and 3.2.2 reproducibly barfed.
I see some changes to ext4 on January 9 and 10. But nothing thereafter so I'm 
not sure if it's worth trying something like 3.3-rc1.
The bad thing is that 3.2 has been working for about 20 hours, so it's not a 
quick test.

> > >>>>> this is a problem which apparently occurred when the user went from
> > >>>> v3.1.5 to v3.2, so this looks likes 3.2 regression.)

> > >> It happened for me on a freshly created FS.
> > >> "mke2fs -j -O sparse_super -O dir_index -O extents -O filetype -O uninit_
> bg"
> > >> mounted with no additional options for the first time I got an
> > >> "EXT4-fs error (device md127): ext4_mb_generate_buddy:739: group 28671, 
> 32765 
> > >> clusters in bitmap, 32766 in gd"
> > >> after writing about 3TB of data.
> > >> I do not have RO snapshots as the OP, but my md sits on top of luks 
> > > containers. 
> > >> So we do have the device mapper in common.
> > > 
> > > After I did an fsck and tried to continue, I didn't get that far.
> > > After another 200GB or so it happened again.
> > > And now it's reproducible:
> > > I can run fsck and then try to continue (using rsync). But as soon as 
> writing 
> > > starts, the process hangs for a long time. At least one minute, probably 
> longer.
> > > Then the ext4_mb_generate_buddy comes again.

  Greetings,
    WIMPy