xfs: more multi-block atomic writes tests

xfs: more multi-block atomic writes tests

Add xfs specific tests for realtime volumes and error recovery.

The first test validates multi-block atomic writes on a realtime file. We
perform basic atomic writes operations within the advertised sizes and ensure
that atomic writes will fail outside of these bounds. The hardware used in this
test is not required to support atomic writes.

The second test verifies that a large atomic write can complete after a crash.
The error is injected while attempting to free an extent. We ensure that this
error occurs by first creating a heavily fragmented filesystem. After recovery,
we check that the write completes successfully.

The third test verifies that a large atomic write on a reflinked file can
complete after a crash. We start with two files that share the same data and
inject an error while attempting to perform a write on one of the files. After
recovery, we verify that these files now contain different data, indicating
that the write has succeeded.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>