Test that if we punch a hole in a file, with either a range that goes
beyond the file's size or covers a file range that is already a hole,
and that if after we do some buffered write operations that cover
different parts of the hole, no warnings are emmitted in syslog/dmesg
and the file's content is correct after remounting the filesystem.
This test is motivated by a bug in btrfs that is manifested in kernel
4.12-rc1 onwards (the bug existed long time ago but was not so easy
to expose before 4.12-rc1). The btrfs patch that fixes the issue is
titled: "Btrfs: fix invalid extent maps due to hole punching".
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>
Filipe Manana