SUNRPC: Add a helper to allow pNFS drivers to selectively cancel RPC calls

Add the helper rpc_cancel_tasks(), which uses a caller-defined selection
function to define a set of in-flight RPC calls to cancel. This is
mainly intended for pNFS drivers which are subject to a layout recall,
and which may therefore want to cancel all pending I/O using that layout
in order to redrive it after the layout recall has been satisfied.

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

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index 647247040ef94bc1fd7c93084c280960e1c5f82d..cdcf0fe56a6feb021f97313389dd2dca6883710b 100644 (file)
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -210,11 +210,16 @@ struct rpc_task *rpc_run_bc_task(struct rpc_rqst *req);
 void           rpc_put_task(struct rpc_task *);
 void           rpc_put_task_async(struct rpc_task *);
 bool           rpc_task_set_rpc_status(struct rpc_task *task, int rpc_status);
+void           rpc_task_try_cancel(struct rpc_task *task, int error);
 void           rpc_signal_task(struct rpc_task *);
 void           rpc_exit_task(struct rpc_task *);
 void           rpc_exit(struct rpc_task *, int);
 void           rpc_release_calldata(const struct rpc_call_ops *, void *);
 void           rpc_killall_tasks(struct rpc_clnt *);
+unsigned long  rpc_cancel_tasks(struct rpc_clnt *clnt, int error,
+                                bool (*fnmatch)(const struct rpc_task *,
+                                                const void *),
+                                const void *data);
 void           rpc_execute(struct rpc_task *);
 void           rpc_init_priority_wait_queue(struct rpc_wait_queue *, const char *);
 void           rpc_init_wait_queue(struct rpc_wait_queue *, const char *);

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index a8c341e4351015b6a036742319e8c4640f5beb7a..57677517b47478b9023e0005e0fc36c574976682 100644 (file)
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -873,6 +873,43 @@ void rpc_killall_tasks(struct rpc_clnt *clnt)
 }
 EXPORT_SYMBOL_GPL(rpc_killall_tasks);
 
+/**
+ * rpc_cancel_tasks - try to cancel a set of RPC tasks
+ * @clnt: Pointer to RPC client
+ * @error: RPC task error value to set
+ * @fnmatch: Pointer to selector function
+ * @data: User data
+ *
+ * Uses @fnmatch to define a set of RPC tasks that are to be cancelled.
+ * The argument @error must be a negative error value.
+ */
+unsigned long rpc_cancel_tasks(struct rpc_clnt *clnt, int error,
+                              bool (*fnmatch)(const struct rpc_task *,
+                                              const void *),
+                              const void *data)
+{
+       struct rpc_task *task;
+       unsigned long count = 0;
+
+       if (list_empty(&clnt->cl_tasks))
+               return 0;
+       /*
+        * Spin lock all_tasks to prevent changes...
+        */
+       spin_lock(&clnt->cl_lock);
+       list_for_each_entry(task, &clnt->cl_tasks, tk_task) {
+               if (!RPC_IS_ACTIVATED(task))
+                       continue;
+               if (!fnmatch(task, data))
+                       continue;
+               rpc_task_try_cancel(task, error);
+               count++;
+       }
+       spin_unlock(&clnt->cl_lock);
+       return count;
+}
+EXPORT_SYMBOL_GPL(rpc_cancel_tasks);
+
 /*
  * Properly shut down an RPC client, terminating all outstanding
  * requests.

diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index f388bfaf6ff03f0583cf83eabc14a5291076b7b5..de912e02371bac6458523a2b10fc4998729e3635 100644 (file)
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -872,6 +872,17 @@ void rpc_signal_task(struct rpc_task *task)
                rpc_wake_up_queued_task(queue, task);
 }
 
+void rpc_task_try_cancel(struct rpc_task *task, int error)
+{
+       struct rpc_wait_queue *queue;
+
+       if (!rpc_task_set_rpc_status(task, error))
+               return;
+       queue = READ_ONCE(task->tk_waitqueue);
+       if (queue)
+               rpc_wake_up_queued_task(queue, task);
+}
+
 void rpc_exit(struct rpc_task *task, int status)
 {
        task->tk_status = status;