nfs41: Add backchannel processing support to RPC state machine

[safe/jmp/linux-2.6] / net / sunrpc / xprt.c

diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index 52739f8..0eea2bf 100644 (file)
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -12,8 +12,9 @@
  *  -  Next, the caller puts together the RPC message, stuffs it into
  *     the request struct, and calls xprt_transmit().
  *  -  xprt_transmit sends the message and installs the caller on the
- *     transport's wait list. At the same time, it installs a timer that
- *     is run after the packet's timeout has expired.
+ *     transport's wait list. At the same time, if a reply is expected,
+ *     it installs a timer that is run after the packet's timeout has
+ *     expired.
  *  -  When a packet arrives, the data_ready handler walks the list of
  *     pending requests for that transport. If a matching XID is found, the
  *     caller is woken up, and the timer removed.
@@ -46,6 +47,8 @@
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/metrics.h>
 
+#include "sunrpc.h"
+
 /*
  * Local variables
  */
@@ -873,7 +876,10 @@ void xprt_transmit(struct rpc_task *task)
        dprintk("RPC: %5u xprt_transmit(%u)\n", task->tk_pid, req->rq_slen);
 
        if (!req->rq_received) {
-               if (list_empty(&req->rq_list)) {
+               if (list_empty(&req->rq_list) && rpc_reply_expected(task)) {
+                       /*
+                        * Add to the list only if we're expecting a reply
+                        */
                        spin_lock_bh(&xprt->transport_lock);
                        /* Update the softirq receive buffer */
                        memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
@@ -908,8 +914,13 @@ void xprt_transmit(struct rpc_task *task)
        /* Don't race with disconnect */
        if (!xprt_connected(xprt))
                task->tk_status = -ENOTCONN;
-       else if (!req->rq_received)
+       else if (!req->rq_received && rpc_reply_expected(task)) {
+               /*
+                * Sleep on the pending queue since
+                * we're expecting a reply.
+                */
                rpc_sleep_on(&xprt->pending, task, xprt_timer);
+       }
        spin_unlock_bh(&xprt->transport_lock);
 }
 
@@ -982,11 +993,17 @@ static void xprt_request_init(struct rpc_task *task, struct rpc_xprt *xprt)
  */
 void xprt_release(struct rpc_task *task)
 {
-       struct rpc_xprt *xprt = task->tk_xprt;
+       struct rpc_xprt *xprt;
        struct rpc_rqst *req;
+       int is_bc_request;
 
        if (!(req = task->tk_rqstp))
                return;
+
+       /* Preallocated backchannel request? */
+       is_bc_request = bc_prealloc(req);
+
+       xprt = req->rq_xprt;
        rpc_count_iostats(task);
        spin_lock_bh(&xprt->transport_lock);
        xprt->ops->release_xprt(xprt, task);
@@ -999,10 +1016,19 @@ void xprt_release(struct rpc_task *task)
                mod_timer(&xprt->timer,
                                xprt->last_used + xprt->idle_timeout);
        spin_unlock_bh(&xprt->transport_lock);
-       xprt->ops->buf_free(req->rq_buffer);
+       if (!bc_prealloc(req))
+               xprt->ops->buf_free(req->rq_buffer);
        task->tk_rqstp = NULL;
        if (req->rq_release_snd_buf)
                req->rq_release_snd_buf(req);
+
+       /*
+        * Early exit if this is a backchannel preallocated request.
+        * There is no need to have it added to the RPC slot list.
+        */
+       if (is_bc_request)
+               return;
+
        memset(req, 0, sizeof(*req));   /* mark unused */
 
        dprintk("RPC: %5u release request %p\n", task->tk_pid, req);