nfsstat: fix a bug in diff_stats()

	Fix a bug in diff_stats() that causes false-positives in
has_stats(), which can result in a bunch of zeros being displayed instead
of suppressed as intended.

Signed-off-by: David M. Richter <richterd@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>

1 files changed, 25 insertions, 4 deletions

diff --git a/utils/nfsstat/nfsstat.c b/utils/nfsstat/nfsstat.c
index eb6e45d..1c44050 100644
--- a/utils/nfsstat/nfsstat.c
+++ b/utils/nfsstat/nfsstat.c
@@ -671,16 +671,37 @@ copy_stats(struct statinfo *dest, struct statinfo *src)
 static void
 diff_stats(struct statinfo *new, struct statinfo *old)
 {
-	int i, j, is_srv, should_diff;
-
+	int i, j, is_srv, nodiff_first_index, should_diff;
+
+	/*
+	 * Different stat types have different formats in the /proc
+	 * files: for the proc2/3/4-type stats, the first entry has
+	 * the total number of subsequent entries; one does not want
+	 * to diff that first entry.  The other stat types aren't like
+	 * this.  So, we diff a given entry if it's not of one of the
+	 * procX types ("i" < 2 for clt, < 4 for srv), or if it's not
+	 * the first entry ("j" > 0).
+	 */
 	is_srv = (new == srvinfo);
+	nodiff_first_index = 2 + (2 * is_srv);
+
 	for (i = 0; old[i].tag; i++) {
 		for (j = 0; j < new[i].nrvals; j++) {
-			/* skip items in valptr that shouldn't be changed */
-			should_diff = (i < (3 + is_srv) || j > 0);
+			should_diff = (i < nodiff_first_index || j > 0);
 			if (should_diff)
 				new[i].valptr[j] -= old[i].valptr[j];
 		}
+
+		/*
+		 * Make sure that the "totals" entry (last value in
+		 * each stat array) for the procX-type stats has the
+		 * "numentries" entry's (first value in procX-type
+		 * stat arrays) constant value added-back after the
+		 * diff -- i.e., it should always be included in the
+		 * total.
+		 */
+		if (!strncmp("proc", new[i].tag, 4))
+			new[i].valptr[new[i].nrvals - 1] += new[i].valptr[0];
 	}
 }