libxfs: readahead of dir3 data blocks should use the read verifier

libxfs: readahead of dir3 data blocks should use the read verifier

In the dir3 data block readahead function, use the regular read
verifier to check the block's CRC and spot-check the block contents
instead of calling the spot-checking routine directly.  This prevents
corrupted directory data blocks from being read into the kernel, which
can lead to garbage ls output and directory loops (if say one of the
entries contains invalid characters).

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>