[sheepdog] [PATCH 2/3] sheep: count prevent cow requests in a correct manner

[Hitoshi Mitake]

Multiple execution of "dog vdi snapshot" can be overlapped. The
variable should not be boolean.

Signed-off-by: Hitoshi Mitake <mitake.hitoshi at lab.ntt.co.jp>
---
 sheep/ops.c        |    6 ++++--
 sheep/request.c    |    2 +-
 sheep/sheep_priv.h |    2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/sheep/ops.c b/sheep/ops.c
index 3432c83..3bf4838 100644
--- a/sheep/ops.c
+++ b/sheep/ops.c
@@ -1207,7 +1207,7 @@ static int local_prevent_cow(const struct sd_req *req, struct sd_rsp *rsp,
 	sd_debug("preventing COW request, ongoing COW requests: %d",
 		 sys->nr_ongoing_cow_request);
 
-	sys->prevent_cow = true;
+	sys->nr_prevent_cow++;
 
 	if (sys->nr_ongoing_cow_request) {
 		list_add_tail(&rq->pending_prevent_cow_request_list,
@@ -1224,8 +1224,10 @@ static int local_allow_cow(const struct sd_req *req, struct sd_rsp *rsp,
 	struct request *rq;
 
 	sd_debug("allowing COW request");
+	sys->nr_prevent_cow--;
 
-	sys->prevent_cow = false;
+	if (sys->nr_prevent_cow)
+		return SD_RES_SUCCESS;
 
 	list_for_each_entry(rq, &sys->prevented_cow_request_queue,
 			    prevented_cow_request_list) {
diff --git a/sheep/request.c b/sheep/request.c
index f5150d5..5a251c2 100644
--- a/sheep/request.c
+++ b/sheep/request.c
@@ -353,7 +353,7 @@ queue_work:
 	}
 
 	if (req->rq.opcode == SD_OP_WRITE_OBJ && is_data_vid_update(&req->rq)) {
-		if (sys->prevent_cow) {
+		if (sys->nr_prevent_cow) {
 			sd_debug("preventing COW");
 			list_add_tail(&req->prevented_cow_request_list,
 				      &sys->prevented_cow_request_queue);
diff --git a/sheep/sheep_priv.h b/sheep/sheep_priv.h
index a876fe5..0c590c0 100644
--- a/sheep/sheep_priv.h
+++ b/sheep/sheep_priv.h
@@ -166,7 +166,7 @@ struct system_info {
 	bool upgrade;
 	struct sd_stat stat;
 
-	bool prevent_cow;
+	int nr_prevent_cow;
 	int nr_ongoing_cow_request;
 	struct list_head prevented_cow_request_queue;
 	struct list_head pending_prevent_cow_request_queue;
-- 
1.7.1