When running xfstests with an external log, the metadump tests fail
with extra output like:
    +filesystem is marked as having an external log; specify logdev on the mount command line.
    +xfs_metadump: cannot read superblock for ag 0
Add a _scratch_metadump() function to handle different logdev
configurations automatically for metadump.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Rich Johnston <rjohnston@sgi.com>
     echo $SCRATCH_OPTIONS $MKFS_OPTIONS $* $SCRATCH_DEV
 }
 
+_scratch_metadump()
+{
+       dumpfile=$1
+       options=
+
+       [ "$USE_EXTERNAL" = yes -a ! -z "$SCRATCH_LOGDEV" ] && \
+               options="-l $SCRATCH_LOGDEV"
+
+       xfs_metadump $options $SCRATCH_DEV $dumpfile
+}
 
 _setup_large_xfs_fs()
 {
 
 cd $here
 
 _scratch_unmount
-
-xfs_metadump -f "${SCRATCH_DEV}" "${METADUMP_FILE}"
+_scratch_metadump $METADUMP_FILE
 
 # Now restore the obfuscated one back and take a look around
 xfs_mdrestore "${METADUMP_FILE}" "${SCRATCH_DEV}"
 
 
 # Yes they can!  Now...
 # Can xfs_metadump cope with this monster?
-xfs_metadump $SCRATCH_DEV $tmp.metadump || _fail "xfs_metadump failed"
+_scratch_metadump $tmp.metadump || _fail "xfs_metadump failed"
 xfs_mdrestore $tmp.metadump $tmp.img || _fail "xfs_mdrestore failed"
 xfs_repair $tmp.img >> $seqres.full 2>&1 || _fail "xfs_repair of metadump failed"