NFSv4: stateful NFSv4 RPC call interface

 The NFSv4 model requires us to complete all RPC calls that might
 establish state on the server whether or not the user wants to
 interrupt it. We may also need to schedule new work (including
 new RPC calls) in order to cancel the new state.

 The asynchronous RPC model will allow us to ensure that RPC calls
 always complete, but in order to allow for "synchronous" RPC, we
 want to add the ability to wait for completion.
 The waits are, of course, interruptible.

 Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 19 insertions, 2 deletions

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index ac1326fc3e1..94b0afa4ab0 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -42,6 +42,7 @@ struct rpc_task {
 #ifdef RPC_DEBUG
         unsigned long           tk_magic;       /* 0xf00baa */
 #endif
+        atomic_t                tk_count;       /* Reference count */
         struct list_head        tk_task;        /* global list of tasks */
         struct rpc_clnt *       tk_client;      /* RPC client */
         struct rpc_rqst *       tk_rqstp;       /* RPC request */
@@ -78,7 +79,6 @@ struct rpc_task {
         struct timer_list       tk_timer;       /* kernel timer */
         unsigned long           tk_timeout;     /* timeout for rpc_sleep() */
         unsigned short          tk_flags;       /* misc flags */
-        unsigned char           tk_active   : 1;/* Task has been activated */
         unsigned char           tk_priority : 2;/* Task priority */
         unsigned long           tk_runstate;    /* Task run status */
         struct workqueue_struct *tk_workqueue;  /* Normally rpciod, but could
@@ -136,7 +136,6 @@ struct rpc_call_ops {
 #define RPC_IS_SWAPPER(t)       ((t)->tk_flags & RPC_TASK_SWAPPER)
 #define RPC_DO_ROOTOVERRIDE(t)  ((t)->tk_flags & RPC_TASK_ROOTCREDS)
 #define RPC_ASSASSINATED(t)     ((t)->tk_flags & RPC_TASK_KILLED)
-#define RPC_IS_ACTIVATED(t)     ((t)->tk_active)
 #define RPC_DO_CALLBACK(t)      ((t)->tk_callback != NULL)
 #define RPC_IS_SOFT(t)          ((t)->tk_flags & RPC_TASK_SOFT)
 #define RPC_TASK_UNINTERRUPTIBLE(t) ((t)->tk_flags & RPC_TASK_NOINTR)
@@ -145,6 +144,7 @@ struct rpc_call_ops {
 #define RPC_TASK_QUEUED         1
 #define RPC_TASK_WAKEUP         2
 #define RPC_TASK_HAS_TIMER      3
+#define RPC_TASK_ACTIVE         4
 
 #define RPC_IS_RUNNING(t)       (test_bit(RPC_TASK_RUNNING, &(t)->tk_runstate))
 #define rpc_set_running(t)      (set_bit(RPC_TASK_RUNNING, &(t)->tk_runstate))
@@ -175,6 +175,15 @@ struct rpc_call_ops {
                 smp_mb__after_clear_bit(); \
         } while (0)
 
+#define RPC_IS_ACTIVATED(t)     (test_bit(RPC_TASK_ACTIVE, &(t)->tk_runstate))
+#define rpc_set_active(t)       (set_bit(RPC_TASK_ACTIVE, &(t)->tk_runstate))
+#define rpc_clear_active(t)     \
+        do { \
+                smp_mb__before_clear_bit(); \
+                clear_bit(RPC_TASK_ACTIVE, &(t)->tk_runstate); \
+                smp_mb__after_clear_bit(); \
+        } while(0)
+
 /*
  * Task priorities.
  * Note: if you change these, you must also change
@@ -237,6 +246,8 @@ struct rpc_wait_queue {
  */
 struct rpc_task *rpc_new_task(struct rpc_clnt *, int flags,
                                 const struct rpc_call_ops *ops, void *data);
+struct rpc_task *rpc_run_task(struct rpc_clnt *clnt, int flags,
+                                const struct rpc_call_ops *ops, void *data);
 struct rpc_task *rpc_new_child(struct rpc_clnt *, struct rpc_task *parent);
 void            rpc_init_task(struct rpc_task *task, struct rpc_clnt *clnt,
                                 int flags, const struct rpc_call_ops *ops,
@@ -260,6 +271,7 @@ void *		rpc_malloc(struct rpc_task *, size_t);
 int             rpciod_up(void);
 void            rpciod_down(void);
 void            rpciod_wake_up(void);
+int             __rpc_wait_for_completion_task(struct rpc_task *task, int (*)(void *));
 #ifdef RPC_DEBUG
 void            rpc_show_tasks(void);
 #endif
@@ -272,6 +284,11 @@ static inline void rpc_exit(struct rpc_task *task, int status)
         task->tk_action = rpc_exit_task;
 }
 
+static inline int rpc_wait_for_completion_task(struct rpc_task *task)
+{
+        return __rpc_wait_for_completion_task(task, NULL);
+}
+
 #ifdef RPC_DEBUG
 static inline const char * rpc_qname(struct rpc_wait_queue *q)
 {