rpc: add owner xlator argument to rpc_clnt_new

The @owner argument tells RPC layer the xlator that owns
the connection and to which xlator THIS needs be set during
network notifications like CONNECT and DISCONNECT.

Code paths that originate from the head of a (volume) graph and use
STACK_WIND ensure that the RPC local endpoint has the right xlator saved
in the frame of the call (callback pair). This guarantees that the
callback is executed in the right xlator context.

The client handshake process which includes fetching of brick ports from
glusterd, setting lk-version on the brick for the session, don't have
the correct xlator set in their frames. The problem lies with RPC
notifications. It doesn't have the provision to set THIS with the xlator
that is registered with the corresponding RPC programs. e.g,
RPC_CLNT_CONNECT event received by protocol/client doesn't have THIS set
to its xlator. This implies, call(-callbacks) originating from this
thread don't have the right xlator set too.

The fix would be to save the xlator registered with the RPC connection
during rpc_clnt_new. e.g, protocol/client's xlator would be saved with
the RPC connection that it 'owns'. RPC notifications such as CONNECT,
DISCONNECT, etc inherit THIS from the RPC connection's xlator.

Change-Id: I9dea2c35378c511d800ef58f7fa2ea5552f2c409
BUG: 1253212
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/11436
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
(cherry picked from commit f7668938cd7745d024f3d2884e04cd744d0a69ab)
Reviewed-on: http://review.gluster.org/11908
Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>

2 files changed, 21 insertions, 2 deletions

diff --git a/rpc/rpc-lib/src/rpc-clnt.c b/rpc/rpc-lib/src/rpc-clnt.c
index 5fbe072033a..1d878663611 100644
--- a/rpc/rpc-lib/src/rpc-clnt.c
+++ b/rpc/rpc-lib/src/rpc-clnt.c
@@ -817,6 +817,16 @@ out:
 static void
 rpc_clnt_destroy (struct rpc_clnt *rpc);
 
+#define RPC_THIS_SAVE(xl) do {                                  \
+        old_THIS = THIS ;                                       \
+        if (!old_THIS)                                          \
+                gf_log_callingfn ("rpc", GF_LOG_CRITICAL,       \
+                                  "THIS is not initialised.");  \
+        THIS = xl;                                              \
+} while (0)
+
+#define RPC_THIS_RESTORE        (THIS = old_THIS)
+
 int
 rpc_clnt_notify (rpc_transport_t *trans, void *mydata,
                  rpc_transport_event_t event, void *data, ...)
@@ -828,6 +838,7 @@ rpc_clnt_notify (rpc_transport_t *trans, void *mydata,
         rpc_transport_pollin_t *pollin      = NULL;
         struct timespec         ts          = {0, };
         void                   *clnt_mydata = NULL;
+        DECLARE_OLD_THIS;
 
         conn = mydata;
         if (conn == NULL) {
@@ -837,6 +848,8 @@ rpc_clnt_notify (rpc_transport_t *trans, void *mydata,
         if (!clnt)
                 goto out;
 
+        RPC_THIS_SAVE (clnt->owner);
+
         switch (event) {
         case RPC_TRANSPORT_DISCONNECT:
         {
@@ -937,6 +950,7 @@ rpc_clnt_notify (rpc_transport_t *trans, void *mydata,
         }
 
 out:
+        RPC_THIS_RESTORE;
         return ret;
 }
 
@@ -1041,11 +1055,13 @@ out:
 }
 
 struct rpc_clnt *
-rpc_clnt_new (dict_t *options, glusterfs_ctx_t *ctx, char *name,
+rpc_clnt_new (dict_t *options, xlator_t *owner, char *name,
               uint32_t reqpool_size)
 {
         int                    ret  = -1;
         struct rpc_clnt       *rpc  = NULL;
+        glusterfs_ctx_t       *ctx  = owner->ctx;
+
 
         rpc = GF_CALLOC (1, sizeof (*rpc), gf_common_mt_rpcclnt_t);
         if (!rpc) {
@@ -1054,6 +1070,7 @@ rpc_clnt_new (dict_t *options, glusterfs_ctx_t *ctx, char *name,
 
         pthread_mutex_init (&rpc->lock, NULL);
         rpc->ctx = ctx;
+        rpc->owner = owner;
 
         if (!reqpool_size)
                 reqpool_size = RPC_CLNT_DEFAULT_REQUEST_COUNT;
diff --git a/rpc/rpc-lib/src/rpc-clnt.h b/rpc/rpc-lib/src/rpc-clnt.h
index ee46a9a9263..6a4bb40793f 100644
--- a/rpc/rpc-lib/src/rpc-clnt.h
+++ b/rpc/rpc-lib/src/rpc-clnt.h
@@ -188,9 +188,11 @@ typedef struct rpc_clnt {
         int                   refcount;
         int                   auth_null;
         char                  disabled;
+        xlator_t             *owner;
 } rpc_clnt_t;
 
-struct rpc_clnt *rpc_clnt_new (dict_t *options, glusterfs_ctx_t *ctx,
+
+struct rpc_clnt *rpc_clnt_new (dict_t *options, xlator_t *owner,
                                char *name, uint32_t reqpool_size);
 
 int rpc_clnt_start (struct rpc_clnt *rpc);