SUNRPC: Add a flag to avoid reference counts on credentials

Add a flag to signal to the RPC layer that the credential is already
pinned for the duration of the RPC call.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

include/linux/sunrpc/sched.h

@@ -132,6 +132,7 @@ struct rpc_task_setup {
 #define RPC_TASK_TIMEOUT	0x1000		/* fail with ETIMEDOUT on timeout */
 #define RPC_TASK_NOCONNECT	0x2000		/* return ENOTCONN if not connected */
 #define RPC_TASK_NO_RETRANS_TIMEOUT	0x4000		/* wait forever for a reply */
+#define RPC_TASK_CRED_NOREF	0x8000		/* No refcount on the credential */
 
 #define RPC_IS_ASYNC(t)		((t)->tk_flags & RPC_TASK_ASYNC)
 #define RPC_IS_SWAPPER(t)	((t)->tk_flags & RPC_TASK_SWAPPER)

net/sunrpc/clnt.c

@@ -1099,8 +1099,9 @@ rpc_task_set_rpc_message(struct rpc_task *task, const struct rpc_message *msg)
 		task->tk_msg.rpc_proc = msg->rpc_proc;
 		task->tk_msg.rpc_argp = msg->rpc_argp;
 		task->tk_msg.rpc_resp = msg->rpc_resp;
-		if (msg->rpc_cred != NULL)
-			task->tk_msg.rpc_cred = get_cred(msg->rpc_cred);
+		task->tk_msg.rpc_cred = msg->rpc_cred;
+		if (!(task->tk_flags & RPC_TASK_CRED_NOREF))
+			get_cred(task->tk_msg.rpc_cred);
 	}
 }
 

net/sunrpc/sched.c

@@ -1162,7 +1162,8 @@ static void rpc_release_resources_task(struct rpc_task *task)
 {
 	xprt_release(task);
 	if (task->tk_msg.rpc_cred) {
-		put_cred(task->tk_msg.rpc_cred);
+		if (!(task->tk_flags & RPC_TASK_CRED_NOREF))
+			put_cred(task->tk_msg.rpc_cred);
 		task->tk_msg.rpc_cred = NULL;
 	}
 	rpc_task_release_client(task);