fuse: make request allocations for background processing explicit

There are two types of processing requests in FUSE: synchronous (via
fuse_request_send()) and asynchronous (via adding to fc->bg_queue).

Fortunately, the type of processing is always known in advance, at the time
of request allocation. This preparatory patch utilizes this fact making
fuse_get_req() aware about the type. Next patches will use it.

Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index 6f96a8d..b7c7f30 100644
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -422,7 +422,7 @@
 
 	BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE);
 
-	req = fuse_get_req(fc, 1);
+	req = fuse_get_req_for_background(fc, 1);
 	if (IS_ERR(req)) {
 		rc = PTR_ERR(req);
 		goto err;