ext4: test block group metadata corruption checking and repair
Targeted fuzzing tests which destroy various pieces of filesystem or
block group metadata; the tests look for (a) kernel detection of
corruption, (b) e2fsck repair of said corruption, and (c) post-repair
fs usability.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com>