qemu-traditional/xendisk: properly update stats in ioreq_release()

While for the "normal" case (called from blk_send_response_all())
decrementing requests_finished is correct, doing so in the parse error
case is wrong; requests_inflight needs to be decremented instead.

upstream-commit: ed5477664369c1e9de23b0e7e8f16a418573bd2a

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Reviewed-by: Kevin Wolf <kwolf@xxxxxxxxxx>

--- a/hw/xen_disk.c
+++ b/hw/xen_disk.c
@@ -151,7 +151,7 @@ static void ioreq_finish(struct ioreq *i
     blkdev->requests_finished++;
 }
 
-static void ioreq_release(struct ioreq *ioreq)
+static void ioreq_release(struct ioreq *ioreq, bool finish)
 {
     struct XenBlkDev *blkdev = ioreq->blkdev;
 
@@ -159,7 +159,11 @@ static void ioreq_release(struct ioreq *
     memset(ioreq, 0, sizeof(*ioreq));
     ioreq->blkdev = blkdev;
     LIST_INSERT_HEAD(&blkdev->freelist, ioreq, list);
-    blkdev->requests_finished--;
+    if (finish) {
+        blkdev->requests_finished--;
+    } else {
+        blkdev->requests_inflight--;
+    }
 }
 
 /*
@@ -487,7 +491,7 @@ static void blk_send_response_all(struct
     while (!LIST_EMPTY(&blkdev->finished)) {
         ioreq = LIST_FIRST(&blkdev->finished);
 	send_notify += blk_send_response_one(ioreq);
-	ioreq_release(ioreq);
+        ioreq_release(ioreq, true);
     }
     if (send_notify)
 	xen_be_send_notify(&blkdev->xendev);
@@ -539,7 +543,7 @@ static void blk_handle_requests(struct X
         if (ioreq_parse(ioreq) != 0) {
             if (blk_send_response_one(ioreq))
                 xen_be_send_notify(&blkdev->xendev);
-            ioreq_release(ioreq);
+            ioreq_release(ioreq, false);
             continue;
         }