SUNRPC: Allow the rpc_release() callback to be run on another workqueue

A lot of the work done by the rpc_release() callback is inappropriate for
rpciod as it will often involve things like starting a new rpc call in
order to clean up state after an interrupted NFSv4 open() call, or
calls to mntput(), etc.

This patch allows the caller of rpc_run_task() to specify that the
rpc_release callback should run on a different workqueue than the default
rpciod_workqueue.

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

2 files changed, 22 insertions, 8 deletions

diff --git a/include/linux/sunrpc/sched.h b/include/linux/sunrpc/sched.h
index f689f02e6793..fefb0ab52189 100644
--- a/include/linux/sunrpc/sched.h
+++ b/include/linux/sunrpc/sched.h
@@ -123,6 +123,7 @@ struct rpc_task_setup {
         const struct rpc_message *rpc_message;
         const struct rpc_call_ops *callback_ops;
         void *callback_data;
+        struct workqueue_struct *workqueue;
         unsigned short flags;
         signed char priority;
 };
diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
index 4c669121e607..3e0b22382a3b 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -326,7 +326,7 @@ static void rpc_make_runnable(struct rpc_task *task)
                 int status;
 
                 INIT_WORK(&task->u.tk_work, rpc_async_schedule);
-                status = queue_work(task->tk_workqueue, &task->u.tk_work);
+                status = queue_work(rpciod_workqueue, &task->u.tk_work);
                 if (status < 0) {
                         printk(KERN_WARNING "RPC: failed to add task to queue: error: %d!\n", status);
                         task->tk_status = status;
@@ -832,7 +832,7 @@ static void rpc_init_task(struct rpc_task *task, const struct rpc_task_setup *ta
         task->tk_owner = current->tgid;
 
         /* Initialize workqueue for async tasks */
-        task->tk_workqueue = rpciod_workqueue;
+        task->tk_workqueue = task_setup_data->workqueue;
 
         task->tk_client = task_setup_data->rpc_client;
         if (task->tk_client != NULL) {
@@ -868,7 +868,7 @@ rpc_alloc_task(void)
         return (struct rpc_task *)mempool_alloc(rpc_task_mempool, GFP_NOFS);
 }
 
-static void rpc_free_task(struct rcu_head *rcu)
+static void rpc_free_task_rcu(struct rcu_head *rcu)
 {
         struct rpc_task *task = container_of(rcu, struct rpc_task, u.tk_rcu);
         dprintk("RPC: %5u freeing task\n", task->tk_pid);
@@ -898,12 +898,23 @@ out:
         return task;
 }
 
-
-void rpc_put_task(struct rpc_task *task)
+static void rpc_free_task(struct rpc_task *task)
 {
         const struct rpc_call_ops *tk_ops = task->tk_ops;
         void *calldata = task->tk_calldata;
 
+        if (task->tk_flags & RPC_TASK_DYNAMIC)
+                call_rcu_bh(&task->u.tk_rcu, rpc_free_task_rcu);
+        rpc_release_calldata(tk_ops, calldata);
+}
+
+static void rpc_async_release(struct work_struct *work)
+{
+        rpc_free_task(container_of(work, struct rpc_task, u.tk_work));
+}
+
+void rpc_put_task(struct rpc_task *task)
+{
         if (!atomic_dec_and_test(&task->tk_count))
                 return;
         /* Release resources */
@@ -915,9 +926,11 @@ void rpc_put_task(struct rpc_task *task)
                 rpc_release_client(task->tk_client);
                 task->tk_client = NULL;
         }
-        if (task->tk_flags & RPC_TASK_DYNAMIC)
-                call_rcu_bh(&task->u.tk_rcu, rpc_free_task);
-        rpc_release_calldata(tk_ops, calldata);
+        if (task->tk_workqueue != NULL) {
+                INIT_WORK(&task->u.tk_work, rpc_async_release);
+                queue_work(task->tk_workqueue, &task->u.tk_work);
+        } else
+                rpc_free_task(task);
 }
 EXPORT_SYMBOL_GPL(rpc_put_task);