[Sheepdog] [PATCH 7/8] sheep: fix epoch incrementation

[MORITA Kazutaka]

In join operations, the condition to increment epoch is whether
sheepdog cluster is already running or not.  In this patch, the master
node notifies the information to all the node in the response of join
messages.

Signed-off-by: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
---
 sheep/group.c |   20 ++++++++++++++------
 1 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/sheep/group.c b/sheep/group.c
index 2e378a4..5763dda 100644
--- a/sheep/group.c
+++ b/sheep/group.c
@@ -61,7 +61,8 @@ struct join_message {
 	uint32_t epoch;
 	uint64_t ctime;
 	uint32_t result;
-	uint32_t pad;
+	uint8_t inc_epoch; /* set non-zero when we increment epoch of all nodes */
+	uint8_t pad[3];
 	struct {
 		uint32_t nodeid;
 		uint32_t pid;
@@ -373,7 +374,7 @@ static int is_master(void)
 static int get_cluster_status(struct sheepdog_node_list_entry *from,
 			      struct sheepdog_node_list_entry *entries,
 			      int nr_entries, uint64_t ctime, uint32_t epoch,
-			      uint32_t *status)
+			      uint32_t *status, uint8_t *inc_epoch)
 {
 	int i;
 	int nr_local_entries;
@@ -382,9 +383,14 @@ static int get_cluster_status(struct sheepdog_node_list_entry *from,
 	uint32_t local_epoch;
 
 	*status = sys->status;
+	if (inc_epoch)
+		*inc_epoch = 0;
 
 	switch (sys->status) {
 	case SD_STATUS_OK:
+		if (inc_epoch)
+			*inc_epoch = 1;
+
 		if (nr_entries == 0)
 			break;
 
@@ -485,7 +491,8 @@ static void join(struct join_message *msg)
 
 	msg->result = get_cluster_status(&msg->header.from, entry,
 					 msg->nr_nodes, msg->ctime,
-					 msg->epoch, &msg->cluster_status);
+					 msg->epoch, &msg->cluster_status,
+					 &msg->inc_epoch);
 	msg->nr_sobjs = sys->nr_sobjs;
 	msg->epoch = sys->epoch;
 	msg->ctime = get_cluster_ctime();
@@ -629,7 +636,7 @@ out:
 			msg->header.nodeid, msg->header.pid);
 
 	if (msg->cluster_status == SD_STATUS_OK) {
-		if (sys->status == SD_STATUS_OK) {
+		if (msg->inc_epoch) {
 			nr_nodes = get_ordered_sd_node_list(entry);
 
 			dprintf("update epoch, %d, %d\n", sys->epoch + 1, nr_nodes);
@@ -641,7 +648,8 @@ out:
 			sys->epoch++;
 
 			update_epoch_store(sys->epoch);
-		} else {
+		}
+		if (sys->status != SD_STATUS_OK) {
 			get_vdi_bitmap_from_all();
 			set_global_nr_copies(sys->nr_sobjs);
 			set_cluster_ctime(msg->ctime);
@@ -1212,7 +1220,7 @@ static void __sd_confchg_done(struct cpg_event *cevent)
 			sys->epoch = epoch;
 			msg.ctime = ctime;
 			get_cluster_status(&msg.header.from, entries, nr_entries,
-					   ctime, epoch, &msg.cluster_status);
+					   ctime, epoch, &msg.cluster_status, NULL);
 		} else
 			msg.cluster_status = SD_STATUS_WAIT_FOR_FORMAT;
 
-- 
1.5.6.5