common: use fiemap to count extents and holes

For the follwoing tests, this patch adds general script to get extent and
hole counts.

 xfs/137         (data vs filesize)
 xfs/138         (data vs filesize vs truncate)
 xfs/139         (data vs filesize vs partial truncate)
 xfs/140         (data vs filesize vs extending truncate)
 xfs/179         (data vs filesize w/ fsync)
 xfs/180         (data vs filesize w/ sync)
 xfs/182         (data vs filesize w/ recovery)

It also requires these tests to check for fiemap support.

[dchinner: use _require_xfs_io_command "fiemap" for consistency]

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/xfs/182

@@ -42,6 +42,7 @@ _supported_os Linux IRIX
 
 _require_scratch
 _require_scratch_shutdown
+_require_fiemap
 _scratch_mkfs_xfs >/dev/null 2>&1
 _scratch_mount
 
@@ -59,8 +60,8 @@ _check_files()
 			if [ `ls -l $file | tr -s ' ' | cut -d ' ' -f 5` -eq 32768 ]
 			then
 				# if file has non-zero size but no extents then it's contents will be NULLs, bad.
-				if xfs_bmap $file | grep 'no extents' > /dev/null
-				then
+				num_extents=`_count_extents $file`
+				if [ $num_extents -eq 0 ]; then
 					echo corrupt file $file - non-zero size but no extents
 				else
 					rm -f $file