btrfs: test a compressed send stream scenario that triggered a read corruption

btrfs: test a compressed send stream scenario that triggered a read corruption

Test a scenario of a compressed send stream that triggered a bug in the
extent map merging code introduced in the merge window for 6.11.

The commit that introduced the bug is on its way to Linus' tree and its
subject is:

   "btrfs: introduce new members for extent_map"

The corresponding fix was submitted to the btrfs mailing list, with the
subject:

  "btrfs: fix corrupt read due to bad offset of a compressed extent map"

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>