fuse: fix background request if not connected

request_end() expects fc->num_background and fc->active_background to have
been incremented, which is not the case in fuse_request_send_nowait()
failure path.  So instead just call the ->end() callback (which is actually
set by all callers).
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Ashish Samant <ashish.samant@oracle.com>

fs/fuse/dev.c

@@ -604,13 +604,16 @@ static void fuse_request_send_nowait_locked(struct fuse_conn *fc,
 
 static void fuse_request_send_nowait(struct fuse_conn *fc, struct fuse_req *req)
 {
+	BUG_ON(!req->end);
 	spin_lock(&fc->lock);
 	if (fc->connected) {
 		fuse_request_send_nowait_locked(fc, req);
 		spin_unlock(&fc->lock);
 	} else {
+		spin_unlock(&fc->lock);
 		req->out.h.error = -ENOTCONN;
-		request_end(fc, req);
+		req->end(fc, req);
+		fuse_put_request(fc, req);
 	}
 }