Ensure that the geometry presented in the backup superblocks matches
the primary superblock so that repair can recover the filesystem if
that primary gets corrupted.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Add some helpers to enable us to lock an AG's headers, create btree
cursors for all btrees in that allocation group, and clean up
afterwards.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Create helper functions to record crc and corruption problems, and
deal with any other runtime errors that arise.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Create a probe scrubber with id 0.  This will be used by xfs_scrub to
probe the kernel's abilities to scrub (and repair) the metadata.  We do
this by validating the ioctl inputs from userspace, preparing the
filesystem for a scrub (or a repair) operation, and immediately
returning to userspace.  Userspace can use the returned errno and
structure state to decide (in broad terms) if scrub/repair are
supported by the running kernel.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>