[sheepdog] [PATCH v4] dog/vdi: bug fix for voting majority, add test case to test it

[Ruoyu]

There is a critical error in the function vote_majority_object.
When all the three copies are different, the original logic still
choose the last one as majority.
The root cause is step 2 of the voting algorithm was missed.

Signed-off-by: Ruoyu <liangry at ucweb.com>
---
 dog/vdi.c                | 22 +++++++++++++---
 tests/functional/077     | 65 ++++++++++++++++++++++++++++++++++++++++++++++++
 tests/functional/077.out | 45 +++++++++++++++++++++++++++++++++
 3 files changed, 129 insertions(+), 3 deletions(-)

diff --git a/dog/vdi.c b/dog/vdi.c
index 999d4be..db5fc58 100644
--- a/dog/vdi.c
+++ b/dog/vdi.c
@@ -1578,6 +1578,7 @@ static void vote_majority_object(struct vdi_check_info *info)
 	int count = 0, nr_live_copies = 0;
 	struct vdi_check_work *majority = NULL;
 
+	/* step 1 */
 	for (int i = 0; i < info->nr_copies; i++) {
 		struct vdi_check_work *vcw = &info->vcw[i];
 
@@ -1594,14 +1595,29 @@ static void vote_majority_object(struct vdi_check_info *info)
 			count--;
 	}
 
+	/* step 2 */
+	if (count > 0 && count <= nr_live_copies / 2) {
+		count = 0;
+		for (int i = 0; i < info->nr_copies; i++) {
+			struct vdi_check_work *vcw = &info->vcw[i];
+
+			if (!vcw->object_found)
+				continue;
+			if (!memcmp(majority->hash, vcw->hash,
+						sizeof(vcw->hash)))
+				count++;
+		}
+	}
+
 	if (!majority)
 		info->result = VDI_CHECK_NO_OBJ_FOUND;
-	else if (count < nr_live_copies / 2) {
+	else if (count > nr_live_copies / 2)
+		info->result = VDI_CHECK_SUCCESS;
+	else {
 		/* no majority found */
 		majority = NULL;
 		info->result = VDI_CHECK_NO_MAJORITY_FOUND;
-	} else
-		info->result = VDI_CHECK_SUCCESS;
+	}
 
 	info->majority = majority;
 }
diff --git a/tests/functional/077 b/tests/functional/077
index f2c2211..2ab8e4f 100755
--- a/tests/functional/077
+++ b/tests/functional/077
@@ -82,3 +82,68 @@ _wait_for_sheep 3
 $DOG vdi check test
 
 $DOG cluster shutdown
+
+
+
+read_vdi_from_nodes()
+{
+	for i in `seq 0 $(($1-1))`; do
+		$DOG vdi read test 0 12 -p $((7000+$i))
+		echo ""
+	done
+}
+
+check_vdi_consistance()
+{
+	read_vdi_from_nodes $1
+	$DOG vdi check test
+	read_vdi_from_nodes $1
+}
+
+echo ""
+
+for i in 0 1 2; do
+    _start_sheep $i
+done
+_wait_for_sheep 3
+
+echo "yes" | $DOG cluster format -c 3
+$DOG vdi create test 4M
+echo "hello, copy0" | $DOG vdi write test 0 12
+cp $STORE/0/obj/007c2b2500000000 $STORE/copy0
+echo "hello, copy1" | $DOG vdi write test 0 12
+cp $STORE/1/obj/007c2b2500000000 $STORE/copy1
+echo "hello, copy2" | $DOG vdi write test 0 12
+
+# three copies, two broken objects, no majority
+
+cp $STORE/copy0 $STORE/0/obj/007c2b2500000000
+cp $STORE/copy1 $STORE/1/obj/007c2b2500000000
+check_vdi_consistance 3
+
+for i in 3 4; do
+    _start_sheep $i
+done
+_wait_for_sheep 5
+
+echo "yes" | $DOG cluster format -c 5
+$DOG vdi create test 4M
+echo "hello, copy0" | $DOG vdi write test 0 12
+cp $STORE/0/obj/007c2b2500000000 $STORE/copy0
+echo "hello, copy1" | $DOG vdi write test 0 12
+cp $STORE/1/obj/007c2b2500000000 $STORE/copy1
+
+# five copies, two broken objects(AABBB)
+
+cp $STORE/copy0 $STORE/0/obj/007c2b2500000000
+cp $STORE/copy0 $STORE/1/obj/007c2b2500000000
+check_vdi_consistance 5
+
+# five copies, two broken objects(BABAB)
+
+cp $STORE/copy0 $STORE/1/obj/007c2b2500000000
+cp $STORE/copy0 $STORE/3/obj/007c2b2500000000
+check_vdi_consistance 5
+
+$DOG cluster shutdown
+
diff --git a/tests/functional/077.out b/tests/functional/077.out
index be8c8d7..c966bbf 100644
--- a/tests/functional/077.out
+++ b/tests/functional/077.out
@@ -14,3 +14,48 @@ finish check&repair test
 original data
 no majority of 7c2b2500000000
 finish check&repair test
+
+    __
+   ()'`;
+   /\|`
+  /  |   Caution! The cluster is not empty.
+(/_)_|_  Are you sure you want to continue? [yes/no]: using backend plain store
+hello, copy0
+hello, copy1
+hello, copy2
+no majority of 7c2b2500000000
+finish check&repair test
+hello, copy0
+hello, copy1
+hello, copy2
+    __
+   ()'`;
+   /\|`
+  /  |   Caution! The cluster is not empty.
+(/_)_|_  Are you sure you want to continue? [yes/no]: using backend plain store
+hello, copy0
+hello, copy0
+hello, copy1
+hello, copy1
+hello, copy1
+fixed replica 7c2b2500000000
+fixed replica 7c2b2500000000
+finish check&repair test
+hello, copy1
+hello, copy1
+hello, copy1
+hello, copy1
+hello, copy1
+hello, copy1
+hello, copy0
+hello, copy1
+hello, copy0
+hello, copy1
+fixed replica 7c2b2500000000
+fixed replica 7c2b2500000000
+finish check&repair test
+hello, copy1
+hello, copy1
+hello, copy1
+hello, copy1
+hello, copy1
-- 
1.8.3.2