releases/5.0.4/sunrpc-fix-up-rpc-back-channel-transmission.patch

   1 From 477687e1116ad16180caf8633dd830b296a5ce73 Mon Sep 17 00:00:00 2001
   2 From: Trond Myklebust <trond.myklebust@hammerspace.com>
   3 Date: Tue, 5 Mar 2019 07:30:48 -0500
   4 Subject: SUNRPC: Fix up RPC back channel transmission
   5
   6 From: Trond Myklebust <trond.myklebust@hammerspace.com>
   7
   8 commit 477687e1116ad16180caf8633dd830b296a5ce73 upstream.
   9
  10 Now that transmissions happen through a queue, we require the RPC tasks
  11 to handle error conditions that may have been set while they were
  12 sleeping. The back channel does not currently do this, but assumes
  13 that any error condition happens during its own call to xprt_transmit().
  14
  15 The solution is to ensure that the back channel splits out the
  16 error handling just like the forward channel does.
  17
  18 Fixes: 89f90fe1ad8b ("SUNRPC: Allow calls to xprt_transmit() to drain...")
  19 Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21
  22 ---
  23  net/sunrpc/clnt.c |   61 +++++++++++++++++++++++++++++-------------------------
  24  1 file changed, 33 insertions(+), 28 deletions(-)
  25
  26 --- a/net/sunrpc/clnt.c
  27 +++ b/net/sunrpc/clnt.c
  28 @@ -66,9 +66,6 @@ static void   call_decode(struct rpc_task
  29  static void    call_bind(struct rpc_task *task);
  30  static void    call_bind_status(struct rpc_task *task);
  31  static void    call_transmit(struct rpc_task *task);
  32 -#if defined(CONFIG_SUNRPC_BACKCHANNEL)
  33 -static void    call_bc_transmit(struct rpc_task *task);
  34 -#endif /* CONFIG_SUNRPC_BACKCHANNEL */
  35  static void    call_status(struct rpc_task *task);
  36  static void    call_transmit_status(struct rpc_task *task);
  37  static void    call_refresh(struct rpc_task *task);
  38 @@ -1131,6 +1128,8 @@ rpc_call_async(struct rpc_clnt *clnt, co
  39  EXPORT_SYMBOL_GPL(rpc_call_async);
  40
  41  #if defined(CONFIG_SUNRPC_BACKCHANNEL)
  42 +static void call_bc_encode(struct rpc_task *task);
  43 +
  44  /**
  45   * rpc_run_bc_task - Allocate a new RPC task for backchannel use, then run
  46   * rpc_execute against it
  47 @@ -1152,7 +1151,7 @@ struct rpc_task *rpc_run_bc_task(struct
  48         task = rpc_new_task(&task_setup_data);
  49         xprt_init_bc_request(req, task);
  50
  51 -       task->tk_action = call_bc_transmit;
  52 +       task->tk_action = call_bc_encode;
  53         atomic_inc(&task->tk_count);
  54         WARN_ON_ONCE(atomic_read(&task->tk_count) != 2);
  55         rpc_execute(task);
  56 @@ -2064,6 +2063,16 @@ call_transmit_status(struct rpc_task *ta
  57  }
  58
  59  #if defined(CONFIG_SUNRPC_BACKCHANNEL)
  60 +static void call_bc_transmit(struct rpc_task *task);
  61 +static void call_bc_transmit_status(struct rpc_task *task);
  62 +
  63 +static void
  64 +call_bc_encode(struct rpc_task *task)
  65 +{
  66 +       xprt_request_enqueue_transmit(task);
  67 +       task->tk_action = call_bc_transmit;
  68 +}
  69 +
  70  /*
  71   * 5b. Send the backchannel RPC reply.  On error, drop the reply.  In
  72   * addition, disconnect on connectivity errors.
  73 @@ -2071,26 +2080,23 @@ call_transmit_status(struct rpc_task *ta
  74  static void
  75  call_bc_transmit(struct rpc_task *task)
  76  {
  77 -       struct rpc_rqst *req = task->tk_rqstp;
  78 -
  79 -       if (rpc_task_need_encode(task))
  80 -               xprt_request_enqueue_transmit(task);
  81 -       if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
  82 -               goto out_wakeup;
  83 -
  84 -       if (!xprt_prepare_transmit(task))
  85 -               goto out_retry;
  86 -
  87 -       if (task->tk_status < 0) {
  88 -               printk(KERN_NOTICE "RPC: Could not send backchannel reply "
  89 -                       "error: %d\n", task->tk_status);
  90 -               goto out_done;
  91 +       task->tk_action = call_bc_transmit_status;
  92 +       if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate)) {
  93 +               if (!xprt_prepare_transmit(task))
  94 +                       return;
  95 +               task->tk_status = 0;
  96 +               xprt_transmit(task);
  97         }
  98 +       xprt_end_transmit(task);
  99 +}
 100
 101 -       xprt_transmit(task);
 102 +static void
 103 +call_bc_transmit_status(struct rpc_task *task)
 104 +{
 105 +       struct rpc_rqst *req = task->tk_rqstp;
 106
 107 -       xprt_end_transmit(task);
 108         dprint_status(task);
 109 +
 110         switch (task->tk_status) {
 111         case 0:
 112                 /* Success */
 113 @@ -2104,8 +2110,14 @@ call_bc_transmit(struct rpc_task *task)
 114         case -ENOTCONN:
 115         case -EPIPE:
 116                 break;
 117 +       case -ENOBUFS:
 118 +               rpc_delay(task, HZ>>2);
 119 +               /* fall through */
 120 +       case -EBADSLT:
 121         case -EAGAIN:
 122 -               goto out_retry;
 123 +               task->tk_status = 0;
 124 +               task->tk_action = call_bc_transmit;
 125 +               return;
 126         case -ETIMEDOUT:
 127                 /*
 128                  * Problem reaching the server.  Disconnect and let the
 129 @@ -2124,18 +2136,11 @@ call_bc_transmit(struct rpc_task *task)
 130                  * We were unable to reply and will have to drop the
 131                  * request.  The server should reconnect and retransmit.
 132                  */
 133 -               WARN_ON_ONCE(task->tk_status == -EAGAIN);
 134                 printk(KERN_NOTICE "RPC: Could not send backchannel reply "
 135                         "error: %d\n", task->tk_status);
 136                 break;
 137         }
 138 -out_wakeup:
 139 -       rpc_wake_up_queued_task(&req->rq_xprt->pending, task);
 140 -out_done:
 141         task->tk_action = rpc_exit_task;
 142 -       return;
 143 -out_retry:
 144 -       task->tk_status = 0;
 145  }
 146  #endif /* CONFIG_SUNRPC_BACKCHANNEL */
 147