For ext* fs containing a large hole(larger than 128M), btrfs-convert
will only insert one 128M hole extent and skip the remaining.
This leads to discontinuous file extents.
Add test case for it, and since it's a pinpoint regression test case, no
combination of convert options nor checksum verification.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>