[03/15] rbd: reorder rbd_img_advance()

Commit Message

Hannes Reinecke Jan. 31, 2020, 10:37 a.m. UTC

Reorder switch statement to avoid the use of a label/goto and add
an RBD_IMG_DONE state to signal that the state machine has completed.

Signed-off-by: Hannes Reinecke <[e-mail]>
---
 drivers/block/rbd.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

Patch

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 792180548e89..c80942e08164 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -321,9 +321,9 @@  enum img_req_flags {
 };
 
 enum rbd_img_state {
-	RBD_IMG_START = 1,
+	RBD_IMG_DONE,
+	RBD_IMG_START,
 	RBD_IMG_EXCLUSIVE_LOCK,
-	__RBD_IMG_OBJECT_REQUESTS,
 	RBD_IMG_OBJECT_REQUESTS,
 };
 
@@ -3591,40 +3591,44 @@  static bool rbd_img_advance(struct rbd_img_request *img_req, int *result)
 	struct rbd_device *rbd_dev = img_req->rbd_dev;
 	int ret;
 
-again:
+	dout("%s: img %p state %d\n", __func__, img_req, img_req->state);
 	switch (img_req->state) {
 	case RBD_IMG_START:
 		rbd_assert(!*result);
 
+		img_req->state = RBD_IMG_EXCLUSIVE_LOCK;
 		ret = rbd_img_exclusive_lock(img_req);
 		if (ret < 0) {
 			*result = ret;
+			img_req->state = RBD_IMG_DONE;
 			return true;
 		}
-		img_req->state = RBD_IMG_EXCLUSIVE_LOCK;
-		if (ret > 0)
-			goto again;
-		return false;
+		if (ret == 0)
+			return false;
+		/* fall through */
 	case RBD_IMG_EXCLUSIVE_LOCK:
-		if (*result)
+		if (*result) {
+			img_req->state = RBD_IMG_DONE;
 			return true;
+		}
 
 		rbd_assert(!need_exclusive_lock(img_req) ||
 			   __rbd_is_lock_owner(rbd_dev));
 
+		img_req->state = RBD_IMG_OBJECT_REQUESTS;
 		rbd_img_object_requests(img_req);
 		if (!img_req->pending.num_pending) {
 			*result = img_req->pending.result;
-			img_req->state = RBD_IMG_OBJECT_REQUESTS;
-			goto again;
+			img_req->state = RBD_IMG_DONE;
+			return true;
 		}
-		img_req->state = __RBD_IMG_OBJECT_REQUESTS;
 		return false;
-	case __RBD_IMG_OBJECT_REQUESTS:
+	case RBD_IMG_OBJECT_REQUESTS:
 		if (!pending_result_dec(&img_req->pending, result))
 			return false;
+		img_req->state = RBD_IMG_DONE;
 		/* fall through */
-	case RBD_IMG_OBJECT_REQUESTS:
+	case RBD_IMG_DONE:
 		return true;
 	default:
 		BUG();