[LTP] [PATCH 2/2] fallocate05: Deallocate whole file on bcachefs

[Kent Overstreet]

On Fri, Sep 06, 2024 at 10:02:00AM GMT, Petr Vorel wrote:
> Hi Martin, all,
> 
> [ Cc Kent and Bcachefs ML ]
> 
> > The default deallocation size is likely too small for bcachefs
> > to actually release the blocks. Since it is also a copy-on-write
> > filesystem, deallocated the whole file like on Btrfs.
> 
> Make sense.
> Reviewed-by: Petr Vorel <pvorel@suse.cz>

I haven't looked at this specific test, but one thing that we run into
with the weird CoW behaviour tests in xfstests is that bcachefs btree
nodes are 256k by default - you're going to see weird effects from that
if tests are looking at disk usage.