common: add helper to count number of exclusive extents in a file

Add a new helper that is similar to _count_extents() except that
extents that are shared several times by the file with itself
(reflinked at different file offsets) are accounted 1 time only,
instead of N times.

This is motivated by a subsequent test for btrfs that will use this
new helper, to verify that send streams are issuing reflink
operations.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

diff --git a/common/rc b/common/rc
index 238ffef9d959e5309abcb73724c687e62d7877b5..3c4121780ebf14c10dc652e775676dd51b0b8250 100644 (file)
--- a/common/rc
+++ b/common/rc
@@ -3202,6 +3202,15 @@ _count_extents()
        $XFS_IO_PROG -r -c "fiemap" $1 | tail -n +2 | grep -v hole | wc -l
 }
 
+# Similar to _count_extents() but if any extent is shared multiples times in
+# the file (reflinked to different file offsets), it is accounted as 1 extent
+# instead of N extents.
+_count_exclusive_extents()
+{
+       $XFS_IO_PROG -r -c "fiemap" $1 | tail -n +2 | grep -v hole | \
+               cut -d ' ' -f 3 | sort | uniq | wc -l
+}
+
 _count_holes()
 {
        $XFS_IO_PROG -r -c "fiemap" $1 | tail -n +2 | grep hole | wc -l