bug#8001: cp (8.10) sparse handling fails on compressed btrfs (cp/fiemap-2)

[Chris Mason]

Excerpts from Mike Frysinger's message of 2011-02-19 19:53:18 -0500:
> 2011/2/19 Pádraig Brady:
> > On 19/02/11 18:28, Mike Frysinger wrote:
> >> based on other threads (which i havent been following too closely), did we
> >> settle on this being a btrfs bug ?
> >
> > Nope, cp 8.10 is not absolved yet.
> > It may be btrfs not honoring FIEMAP_FLAG_SYNC,
> > and/or it may be cp needing to handle FIEMAP_EXTENT_ENCODED
> > specially.
> >
> > It would help if you ran `sync` before the copy,
> > to exclude that as a possible issue.
> 
> makes no difference after applying this patch:

I've got a fix for this on the btrfs side in testing.  It is definitely
a btrfs bug.

-chris