rpc: server to client callback mechanism

Signed-off-by: Amar Tumballi <amar@gluster.com>
Signed-off-by: Vijay Bellur <vijay@dev.gluster.com>

19 files changed, 496 insertions, 132 deletions

diff --git a/glusterfsd/src/glusterfsd-mgmt.c b/glusterfsd/src/glusterfsd-mgmt.c
index e6cfa6ac6d1..2602d5431bc 100644
--- a/glusterfsd/src/glusterfsd-mgmt.c
+++ b/glusterfsd/src/glusterfsd-mgmt.c
@@ -43,6 +43,36 @@ static char is_mgmt_rpc_reconnect;
 typedef ssize_t (*mgmt_serialize_t) (struct iovec outmsg, void *args);
 
 
+
+int glusterfs_mgmt_pmap_signin (glusterfs_ctx_t *ctx);
+int glusterfs_volfile_fetch (glusterfs_ctx_t *ctx);
+int glusterfs_process_volfp (glusterfs_ctx_t *ctx, FILE *fp);
+
+int
+mgmt_cbk_spec (void *data)
+{
+        glusterfs_ctx_t *ctx = NULL;
+
+        ctx = glusterfs_ctx_get ();
+        gf_log ("mgmt", GF_LOG_INFO, "Volume file changed");
+
+        glusterfs_volfile_fetch (ctx);
+        return 0;
+}
+
+rpcclnt_cb_actor_t gluster_cbk_actors[] = {
+        [GF_CBK_FETCHSPEC] = {"FETCHSPEC", GF_CBK_FETCHSPEC, mgmt_cbk_spec },
+};
+
+
+struct rpcclnt_cb_program mgmt_cbk_prog = {
+        .progname  = "GlusterFS Callback",
+        .prognum   = GLUSTER_CBK_PROGRAM,
+        .progver   = GLUSTER_CBK_VERSION,
+        .actors    = gluster_cbk_actors,
+        .numactors = GF_CBK_MAXVALUE,
+};
+
 char *clnt_pmap_procs[GF_PMAP_MAXVALUE] = {
         [GF_PMAP_NULL]        = "NULL",
         [GF_PMAP_PORTBYBRICK] = "PORTBYBRICK",
@@ -74,11 +104,6 @@ rpc_clnt_prog_t clnt_handshake_prog = {
         .procnames = clnt_handshake_procs,
 };
 
-
-int glusterfs_mgmt_pmap_signin (glusterfs_ctx_t *ctx);
-int glusterfs_volfile_fetch (glusterfs_ctx_t *ctx);
-int glusterfs_process_volfp (glusterfs_ctx_t *ctx, FILE *fp);
-
 int
 mgmt_submit_request (void *req, call_frame_t *frame,
                      glusterfs_ctx_t *ctx,
@@ -133,7 +158,6 @@ out:
 /* XXX: move these into @ctx */
 static char oldvolfile[131072];
 static int oldvollen = 0;
-static void *timer;
 
 int
 mgmt_getspec_cbk (struct rpc_req *req, struct iovec *iov, int count,
@@ -145,7 +169,6 @@ mgmt_getspec_cbk (struct rpc_req *req, struct iovec *iov, int count,
         int                      ret   = 0;
         ssize_t                  size = 0;
         FILE                    *tmpfp = NULL;
-        struct timeval           tv = {0, };
 
         frame = myframe;
         ctx = frame->this->ctx;
@@ -194,11 +217,6 @@ mgmt_getspec_cbk (struct rpc_req *req, struct iovec *iov, int count,
         }
 
 out:
-        tv.tv_sec = 1;
-        timer = gf_timer_call_after (ctx, tv,
-                                     (gf_timer_cbk_t) glusterfs_volfile_fetch,
-                                     ctx);
-
         STACK_DESTROY (frame->root);
 
         if (rsp.spec)
@@ -216,12 +234,6 @@ glusterfs_volfile_fetch (glusterfs_ctx_t *ctx)
         int               ret = 0;
         call_frame_t     *frame = NULL;
 
-        {
-                if (timer)
-                        gf_timer_call_cancel (ctx, timer);
-                timer = NULL;
-        }
-
         cmd_args = &ctx->cmd_args;
 
         frame = create_frame (THIS, ctx->pool);
@@ -318,6 +330,10 @@ glusterfs_mgmt_init (glusterfs_ctx_t *ctx)
         if (ret)
                 goto out;
 
+        ret = rpcclnt_cbk_program_register (rpc, &mgmt_cbk_prog);
+        if (ret)
+                goto out;
+
 out:
         return ret;
 }
diff --git a/rpc/rpc-lib/src/protocol-common.h b/rpc/rpc-lib/src/protocol-common.h
index 4df5a554fec..fdb42dfe663 100644
--- a/rpc/rpc-lib/src/protocol-common.h
+++ b/rpc/rpc-lib/src/protocol-common.h
@@ -140,6 +140,13 @@ enum gf_probe_resp {
 	GF_PROBE_FRIEND,
 };
 
+enum gf_cbk_procnum {
+        GF_CBK_NULL = 0,
+        GF_CBK_FETCHSPEC,
+        GF_CBK_INO_FLUSH,
+        GF_CBK_MAXVALUE,
+};
+
 #define GLUSTER3_1_FOP_PROGRAM   1298437 /* Completely random */
 #define GLUSTER3_1_FOP_VERSION   310 /* 3.1.0 */
 #define GLUSTER3_1_FOP_PROCCNT   GFS3_OP_MAXVALUE
@@ -152,10 +159,13 @@ enum gf_probe_resp {
 #define GLUSTER3_1_CLI_VERSION   1   /* 0.0.1 */
 #define GLUSTER3_1_CLI_PROCCNT   GF1_CLI_MAXVALUE
 
-#define GLUSTER_HNDSK_PROGRAM   14398633 /* Completely random */
-#define GLUSTER_HNDSK_VERSION   1   /* 0.0.1 */
+#define GLUSTER_HNDSK_PROGRAM    14398633 /* Completely random */
+#define GLUSTER_HNDSK_VERSION    1   /* 0.0.1 */
+
+#define GLUSTER_PMAP_PROGRAM     34123456
+#define GLUSTER_PMAP_VERSION     1
 
-#define GLUSTER_PMAP_PROGRAM    34123456
-#define GLUSTER_PMAP_VERSION    1
+#define GLUSTER_CBK_PROGRAM      52743234 /* Completely random */
+#define GLUSTER_CBK_VERSION      1   /* 0.0.1 */
 
 #endif /* !_PROTOCOL_COMMON_H */
diff --git a/rpc/rpc-lib/src/rpc-clnt.c b/rpc/rpc-lib/src/rpc-clnt.c
index eac9f875066..8d923ed5f43 100644
--- a/rpc/rpc-lib/src/rpc-clnt.c
+++ b/rpc/rpc-lib/src/rpc-clnt.c
@@ -31,6 +31,7 @@
 #include "rpc-transport.h"
 #include "protocol-common.h"
 #include "mem-pool.h"
+#include "xdr-rpc.h"
 
 void
 rpc_clnt_reply_deinit (struct rpc_req *req, struct mem_pool *pool);
@@ -653,6 +654,49 @@ out:
         return ret;
 }
 
+int
+rpc_clnt_handle_cbk (struct rpc_clnt *clnt, rpc_transport_pollin_t *msg)
+{
+        char                 *msgbuf = NULL;
+        rpcclnt_cb_program_t *program = NULL;
+        struct rpc_msg        rpcmsg;
+        struct iovec          progmsg; /* RPC Program payload */
+        size_t                msglen = 0;
+        int                   found  = 0;
+        int                   ret    = -1;
+        int                   procnum = 0;
+
+        msgbuf = msg->vector[0].iov_base;
+        msglen = msg->vector[0].iov_len;
+
+        ret = xdr_to_rpc_call (msgbuf, msglen, &rpcmsg, &progmsg, NULL,NULL);
+        if (ret == -1) {
+                gf_log ("rpc-clnt", GF_LOG_ERROR, "RPC call decoding failed");
+                goto out;
+        }
+
+        gf_log ("rpc-clnt", GF_LOG_INFO, "RPC XID: %lx, Ver: %ld, Program: %ld,"
+                " ProgVers: %ld, Proc: %ld", rpc_call_xid (&rpcmsg),
+                rpc_call_rpcvers (&rpcmsg), rpc_call_program (&rpcmsg),
+                rpc_call_progver (&rpcmsg), rpc_call_progproc (&rpcmsg));
+
+        procnum = rpc_call_progproc (&rpcmsg);
+
+        list_for_each_entry (program, &clnt->programs, program) {
+                if ((program->prognum == rpc_call_program (&rpcmsg))
+                    && (program->progver == rpc_call_progver (&rpcmsg))) {
+                        found = 1;
+                        break;
+                }
+        }
+        if (found && (procnum < program->numactors) &&
+            (program->actors[procnum].actor)) {
+                program->actors[procnum].actor (&progmsg);
+        }
+
+out:
+        return ret;
+}
 
 int
 rpc_clnt_handle_reply (struct rpc_clnt *clnt, rpc_transport_pollin_t *pollin)
@@ -796,7 +840,10 @@ rpc_clnt_notify (rpc_transport_t *trans, void *mydata,
         case RPC_TRANSPORT_MSG_RECEIVED:
         {
                 pollin = data;
-                ret = rpc_clnt_handle_reply (clnt, pollin);
+                if (pollin->is_reply)
+                        ret = rpc_clnt_handle_reply (clnt, pollin);
+                else
+                        ret = rpc_clnt_handle_cbk (clnt, pollin);
                 /* ret = clnt->notifyfn (clnt, clnt->mydata, RPC_CLNT_MSG,
                  * data);
                  */
@@ -943,6 +990,8 @@ rpc_clnt_init (struct rpc_clnt_config *config, dict_t *options,
                 goto out;
         }
 
+        INIT_LIST_HEAD (&rpc->programs);
+
 out:
         return rpc;
 }
@@ -1168,6 +1217,37 @@ out:
         return request_iob;
 }
 
+int
+rpcclnt_cbk_program_register (struct rpc_clnt *clnt,
+                              rpcclnt_cb_program_t *program)
+{
+        int ret = -1;
+
+        if (!clnt)
+                goto out;
+
+        if (program->actors == NULL)
+                goto out;
+
+        INIT_LIST_HEAD (&program->program);
+
+        list_add_tail (&program->program, &clnt->programs);
+
+        ret = 0;
+        gf_log ("rpc-clnt", GF_LOG_DEBUG, "New program registered: %s, Num: %d,"
+                " Ver: %d", program->progname, program->prognum,
+                program->progver);
+
+out:
+        if (ret == -1) {
+                gf_log ("rpc-clnt", GF_LOG_ERROR, "Program registration failed:"
+                        " %s, Num: %d, Ver: %d", program->progname,
+                        program->prognum, program->progver);
+        }
+
+        return ret;
+}
+
 
 int
 rpc_clnt_submit (struct rpc_clnt *rpc, rpc_clnt_prog_t *prog,
diff --git a/rpc/rpc-lib/src/rpc-clnt.h b/rpc/rpc-lib/src/rpc-clnt.h
index 2381aaa087c..a0251c7c551 100644
--- a/rpc/rpc-lib/src/rpc-clnt.h
+++ b/rpc/rpc-lib/src/rpc-clnt.h
@@ -83,6 +83,38 @@ typedef struct rpc_clnt_program {
         int                   numproc;
 } rpc_clnt_prog_t;
 
+typedef int (*rpcclnt_cb_fn) (void *data);
+
+/* The descriptor for each procedure/actor that runs
+ * over the RPC service.
+ */
+typedef struct rpcclnt_actor_desc {
+        char                 procname[32];
+        int                  procnum;
+        rpcclnt_cb_fn        actor;
+} rpcclnt_cb_actor_t;
+
+/* Describes a program and its version along with the function pointers
+ * required to handle the procedures/actors of each program/version.
+ * Never changed ever by any thread so no need for a lock.
+ */
+typedef struct rpcclnt_cb_program {
+        char                      progname[32];
+        int                       prognum;
+        int                       progver;
+        rpcclnt_cb_actor_t       *actors;        /* All procedure handlers */
+        int                       numactors;     /* Num actors in actor array */
+
+        /* Program specific state handed to actors */
+        void                    *private;
+
+
+        /* list member to link to list of registered services with rpc_clnt */
+        struct list_head        program;
+} rpcclnt_cb_program_t;
+
+
+
 #define RPC_MAX_AUTH_BYTES   400
 typedef struct rpc_auth_data {
         int             flavour;
@@ -141,6 +173,9 @@ struct rpc_clnt {
         void                  *mydata;
         uint64_t               xid;
 
+        /* list of cb programs registered with rpc-clnt */
+        struct list_head       programs;
+
         /* Memory pool for rpc_req_t */
         struct mem_pool       *reqpool;
 
@@ -171,7 +206,7 @@ int rpc_clnt_register_notify (struct rpc_clnt *rpc, rpc_clnt_notify_t fn,
  *    also be filled with pointer to buffer to hold header and length
  *    of the header.
  */
- 
+
 int rpc_clnt_submit (struct rpc_clnt *rpc, rpc_clnt_prog_t *prog,
                      int procnum, fop_cbk_fn_t cbkfn,
                      struct iovec *proghdr, int proghdrcount,
@@ -190,4 +225,10 @@ void rpc_clnt_reconnect (void *trans_ptr);
 
 void rpc_clnt_reconfig (struct rpc_clnt *rpc, struct rpc_clnt_config *config);
 
+/* All users of RPC services should use this API to register their
+ * procedure handlers.
+ */
+int rpcclnt_cbk_program_register (struct rpc_clnt *svc,
+                                  rpcclnt_cb_program_t *program);
+
 #endif /* !_RPC_CLNT_H */
diff --git a/rpc/rpc-lib/src/rpc-transport.h b/rpc/rpc-lib/src/rpc-transport.h
index c5b6f382e7b..cccae5f261d 100644
--- a/rpc/rpc-lib/src/rpc-transport.h
+++ b/rpc/rpc-lib/src/rpc-transport.h
@@ -166,6 +166,7 @@ struct rpc_transport_pollin {
         char vectored;
         void *private;
         struct iobref *iobref;
+        char is_reply;
 };
 typedef struct rpc_transport_pollin rpc_transport_pollin_t;
 
@@ -196,6 +197,8 @@ struct rpc_transport {
         void                      *notify_data;
 	peer_info_t                peerinfo;
 	peer_info_t                myinfo;
+
+        struct list_head           list;
 };
 
 struct rpc_transport_ops {
diff --git a/rpc/rpc-lib/src/rpcsvc.c b/rpc/rpc-lib/src/rpcsvc.c
index 5b5c2998c5e..ee3d674c2eb 100644
--- a/rpc/rpc-lib/src/rpcsvc.c
+++ b/rpc/rpc-lib/src/rpcsvc.c
@@ -46,6 +46,8 @@
 #include <stdarg.h>
 #include <stdio.h>
 
+#include "xdr-rpcclnt.h"
+
 struct rpcsvc_program gluster_dump_prog;
 
 #define rpcsvc_alloc_request(svc, request)                              \
@@ -1119,6 +1121,189 @@ err:
         return txrecord;
 }
 
+inline int
+rpcsvc_get_callid (rpcsvc_t *rpc)
+{
+        return GF_UNIVERSAL_ANSWER;
+}
+
+int
+rpcsvc_fill_callback (int prognum, int progver, int procnum, int payload,
+                      uint64_t xid, struct rpc_msg *request)
+{
+        int   ret          = -1;
+
+        if (!request) {
+                goto out;
+        }
+
+        memset (request, 0, sizeof (*request));
+
+        request->rm_xid = xid;
+        request->rm_direction = CALL;
+
+        request->rm_call.cb_rpcvers = 2;
+        request->rm_call.cb_prog = prognum;
+        request->rm_call.cb_vers = progver;
+        request->rm_call.cb_proc = procnum;
+
+        request->rm_call.cb_cred.oa_flavor = AUTH_NONE;
+        request->rm_call.cb_cred.oa_base   = NULL;
+        request->rm_call.cb_cred.oa_length = 0;
+
+        request->rm_call.cb_verf.oa_flavor = AUTH_NONE;
+        request->rm_call.cb_verf.oa_base = NULL;
+        request->rm_call.cb_verf.oa_length = 0;
+
+        ret = 0;
+out:
+        return ret;
+}
+
+
+struct iovec
+rpcsvc_callback_build_header (char *recordstart, size_t rlen,
+                             struct rpc_msg *request, size_t payload)
+{
+        struct iovec    requesthdr = {0, };
+        struct iovec    txrecord   = {0, 0};
+        int             ret        = -1;
+        size_t          fraglen    = 0;
+
+        ret = rpc_request_to_xdr (request, recordstart, rlen, &requesthdr);
+        if (ret == -1) {
+                gf_log ("rpcsvc", GF_LOG_DEBUG,
+                        "Failed to create RPC request");
+                goto out;
+        }
+
+        fraglen = payload + requesthdr.iov_len;
+        gf_log ("rpcsvc", GF_LOG_TRACE, "Request fraglen %zu, payload: %zu, "
+                "rpc hdr: %zu", fraglen, payload, requesthdr.iov_len);
+
+        txrecord.iov_base = recordstart;
+
+        /* Remember, this is only the vec for the RPC header and does not
+         * include the payload above. We needed the payload only to calculate
+         * the size of the full fragment. This size is sent in the fragment
+         * header.
+         */
+        txrecord.iov_len = requesthdr.iov_len;
+
+out:
+        return txrecord;
+}
+
+struct iobuf *
+rpcsvc_callback_build_record (rpcsvc_t *rpc, int prognum, int progver,
+                              int procnum, size_t payload, uint64_t xid,
+                              struct iovec *recbuf)
+{
+        struct rpc_msg           request     = {0, };
+        struct iobuf            *request_iob = NULL;
+        char                    *record      = NULL;
+        struct iovec             recordhdr   = {0, };
+        size_t                   pagesize    = 0;
+        int                      ret         = -1;
+
+        if ((!rpc) || (!recbuf)) {
+                goto out;
+        }
+
+        /* First, try to get a pointer into the buffer which the RPC
+         * layer can use.
+         */
+        request_iob = iobuf_get (rpc->ctx->iobuf_pool);
+        if (!request_iob) {
+                gf_log ("rpcsvc", GF_LOG_ERROR, "Failed to get iobuf");
+                goto out;
+        }
+
+        pagesize = ((struct iobuf_pool *)rpc->ctx->iobuf_pool)->page_size;
+
+        record = iobuf_ptr (request_iob);  /* Now we have it. */
+
+        /* Fill the rpc structure and XDR it into the buffer got above. */
+        ret = rpcsvc_fill_callback (prognum, progver, procnum, payload, xid,
+                                    &request);
+        if (ret == -1) {
+                gf_log ("rpcsvc", GF_LOG_DEBUG, "cannot build a rpc-request "
+                        "xid (%"PRIu64")", xid);
+                goto out;
+        }
+
+        recordhdr = rpcsvc_callback_build_header (record, pagesize, &request,
+                                                  payload);
+
+        if (!recordhdr.iov_base) {
+                gf_log ("rpc-clnt", GF_LOG_ERROR, "Failed to build record "
+                        " header");
+                iobuf_unref (request_iob);
+                request_iob = NULL;
+                recbuf->iov_base = NULL;
+                goto out;
+        }
+
+        recbuf->iov_base = recordhdr.iov_base;
+        recbuf->iov_len = recordhdr.iov_len;
+
+out:
+        return request_iob;
+}
+
+int
+rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
+                        rpcsvc_cbk_program_t *prog, int procnum,
+                        struct iovec *proghdr, int proghdrcount)
+{
+        struct iobuf          *request_iob = NULL;
+        struct iovec           rpchdr      = {0,};
+        rpc_transport_req_t    req;
+        int                    ret         = -1;
+        int                    proglen     = 0;
+        uint64_t               callid      = 0;
+
+        if (!rpc) {
+                goto out;
+        }
+
+        memset (&req, 0, sizeof (req));
+
+        callid = rpcsvc_get_callid (rpc);
+
+        if (proghdr) {
+                proglen += iov_length (proghdr, proghdrcount);
+        }
+
+        request_iob = rpcsvc_callback_build_record (rpc, prog->prognum,
+                                                    prog->progver, procnum,
+                                                    proglen, callid,
+                                                    &rpchdr);
+        if (!request_iob) {
+                gf_log ("rpcsvc", GF_LOG_DEBUG,
+                        "cannot build rpc-record");
+                goto out;
+        }
+
+        req.msg.rpchdr = &rpchdr;
+        req.msg.rpchdrcount = 1;
+        req.msg.proghdr = proghdr;
+        req.msg.proghdrcount = proghdrcount;
+
+        ret = rpc_transport_submit_request (trans, &req);
+        if (ret == -1) {
+                gf_log ("rpc-clnt", GF_LOG_DEBUG,
+                        "transmission of rpc-request failed");
+                goto out;
+        }
+
+        ret = 0;
+
+out:
+        iobuf_unref (request_iob);
+
+        return ret;
+}
 
 inline int
 rpcsvc_transport_submit (rpc_transport_t *trans, struct iovec *hdrvec,
diff --git a/rpc/rpc-lib/src/rpcsvc.h b/rpc/rpc-lib/src/rpcsvc.h
index 10b20af0a88..fca7d047a7b 100644
--- a/rpc/rpc-lib/src/rpcsvc.h
+++ b/rpc/rpc-lib/src/rpcsvc.h
@@ -375,7 +375,11 @@ struct rpcsvc_program {
         struct list_head        program;
 };
 
-
+typedef struct rpcsvc_cbk_program {
+        char                 *progname;
+        int                   prognum;
+        int                   progver;
+} rpcsvc_cbk_program_t;
 /* All users of RPC services should use this API to register their
  * procedure handlers.
  */
@@ -525,4 +529,9 @@ rpcsvc_combine_gen_spec_volume_checks (int gen, int spec);
 
 extern char *
 rpcsvc_volume_allowed (dict_t *options, char *volname);
+
+int rpcsvc_callback_submit (rpcsvc_t *rpc, rpc_transport_t *trans,
+                            rpcsvc_cbk_program_t *prog, int procnum,
+                            struct iovec *proghdr, int proghdrcount);
+
 #endif
diff --git a/rpc/rpc-transport/socket/src/socket.c b/rpc/rpc-transport/socket/src/socket.c
index 6d2d584d111..26b56fad577 100644
--- a/rpc/rpc-transport/socket/src/socket.c
+++ b/rpc/rpc-transport/socket/src/socket.c
@@ -1477,6 +1477,8 @@ __socket_proto_state_machine (rpc_transport_t *this,
                                         ret = -1;
                                         goto out;
                                 }
+                                if (priv->incoming.msg_type == REPLY)
+                                        (*pollin)->is_reply = 1;
 
                                 priv->incoming.request_info = NULL;
                         }
diff --git a/xlators/mgmt/glusterd/src/glusterd-op-sm.c b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
index ecbe7b150ff..11fca774a9f 100644
--- a/xlators/mgmt/glusterd/src/glusterd-op-sm.c
+++ b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
@@ -254,87 +254,6 @@ out:
         return ret;
 }
 
-int
-glusterd_volume_create_generate_volfiles (glusterd_volinfo_t *volinfo)
-{
-        int32_t         ret = -1;
-        char            cmd_str[8192] = {0,};
-        char            path[PATH_MAX] = {0,};
-        glusterd_conf_t *priv = NULL;
-        xlator_t        *this = NULL;
-        char            bricks[8192] = {0,};
-        glusterd_brickinfo_t    *brickinfo = NULL;
-        int32_t         len = 0;
-
-        this = THIS;
-        GF_ASSERT (this);
-        priv = this->private;
-
-        GF_ASSERT (priv);
-        GF_ASSERT (volinfo);
-
-        GLUSTERD_GET_VOLUME_DIR(path, volinfo, priv);
-        if (!volinfo->port) {
-                //volinfo->port = ++glusterfs_port;
-        }
-
-        list_for_each_entry (brickinfo, &volinfo->bricks, brick_list) {
-                snprintf (bricks + len, 8192 - len, "%s:%s ",
-                          brickinfo->hostname, brickinfo->path);
-                len = strlen (bricks);
-        }
-
-        gf_log ("", GF_LOG_DEBUG, "Brick string: %s", bricks);
-
-        switch (volinfo->type) {
-
-                case GF_CLUSTER_TYPE_REPLICATE:
-                {
-                        snprintf (cmd_str, 8192,
-                                  "%s/bin/glusterfs-volgen --portmapper-mode -n %s "
-                                  " -c %s -r 1 %s -p %d --num-replica %d",
-                                  GFS_PREFIX, volinfo->volname, path, bricks,
-                                  volinfo->port, volinfo->sub_count);
-                        ret = gf_system (cmd_str);
-                        gf_log ("", 1, "%s", cmd_str);
-                        break;
-                }
-
-                case GF_CLUSTER_TYPE_STRIPE:
-                {
-                        snprintf (cmd_str, 8192,
-                                  "%s/bin/glusterfs-volgen --portmapper-mode -n %s "
-                                  " -c %s -r 0 %s -p %d --num-stripe %d",
-                                  GFS_PREFIX, volinfo->volname, path, bricks,
-                                  volinfo->port, volinfo->sub_count);
-                        ret = gf_system (cmd_str);
-                        gf_log ("", 1, "%s", cmd_str);
-                        break;
-                }
-
-                case GF_CLUSTER_TYPE_NONE:
-                {
-                        snprintf (cmd_str, 8192,
-                                  "%s/bin/glusterfs-volgen --portmapper-mode "
-                                  " -n %s -c %s %s -p %d",
-                                  GFS_PREFIX, volinfo->volname, path, bricks,
-                                  volinfo->port);
-                        ret = gf_system (cmd_str);
-                        gf_log ("", 1, "%s", cmd_str);
-                        break;
-                }
-
-                default:
-                        gf_log ("", GF_LOG_ERROR, "Unkown type: %d",
-                                volinfo->type);
-                        ret = -1;
-        }
-//out:
-        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
-        return ret;
-}
-
-
 
 static int
 glusterd_op_stage_create_volume (gd1_mgmt_stage_op_req *req)
@@ -952,8 +871,7 @@ glusterd_op_add_brick (gd1_mgmt_stage_op_req *req)
 
                 if (!ret && (!uuid_compare (brickinfo->uuid, priv->uuid)) &&
                                 (GLUSTERD_STATUS_STARTED == volinfo->status)) {
-                        ret =
-                          glusterd_volume_create_generate_volfiles (volinfo);
+                        ret = glusterd_create_volfiles (volinfo);
                         if (ret)
                                 goto out;
 
@@ -975,7 +893,7 @@ glusterd_op_add_brick (gd1_mgmt_stage_op_req *req)
         }
 
         if (!glfs_started) {
-                ret = glusterd_volume_create_generate_volfiles (volinfo);
+                ret = glusterd_create_volfiles (volinfo);
                 if (ret)
                         goto out;
         }
@@ -1892,8 +1810,7 @@ glusterd_op_remove_brick (gd1_mgmt_stage_op_req *req)
 
                 if ((!uuid_compare (brickinfo->uuid, priv->uuid)) &&
                     (GLUSTERD_STATUS_STARTED == volinfo->status)) {
-                        ret =
-                          glusterd_volume_create_generate_volfiles (volinfo);
+                        ret = glusterd_create_volfiles (volinfo);
                         if (ret)
                                 goto out;
 
@@ -1918,7 +1835,7 @@ glusterd_op_remove_brick (gd1_mgmt_stage_op_req *req)
         }
 
         if (!glfs_stopped) {
-                ret = glusterd_volume_create_generate_volfiles (volinfo);
+                ret = glusterd_create_volfiles (volinfo);
                 if (ret)
                         goto out;
         }
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index 770ee86d43c..cbafb81ec4b 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -1356,7 +1356,7 @@ glusterd_import_friend_volume (dict_t *vols, int count)
                 ret = glusterd_store_update_volume (volinfo);
         }
 
-        ret = glusterd_volume_create_generate_volfiles (volinfo);
+        ret = glusterd_create_volfiles (volinfo);
         if (ret)
                 goto out;
 
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.h b/xlators/mgmt/glusterd/src/glusterd-utils.h
index 1e9469ce0fd..6af21a490fe 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.h
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.h
@@ -127,6 +127,4 @@ glusterd_compare_friend_data (dict_t  *vols, int32_t *status);
 int
 glusterd_volume_compute_cksum (glusterd_volinfo_t  *volinfo);
 
-int
-glusterd_volume_create_generate_volfiles (glusterd_volinfo_t *volinfo);
 #endif
diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.c b/xlators/mgmt/glusterd/src/glusterd-volgen.c
index 10ee80e359c..ee7d6839197 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.c
@@ -1683,6 +1683,8 @@ glusterd_create_volfiles (glusterd_volinfo_t *volinfo)
                 goto out;
         }
 
+        ret = glusterd_fetchspec_notify (THIS);
+
 out:
         return ret;
 }
diff --git a/xlators/mgmt/glusterd/src/glusterd.c b/xlators/mgmt/glusterd/src/glusterd.c
index 1d19c7ed80a..d23f06190d7 100644
--- a/xlators/mgmt/glusterd/src/glusterd.c
+++ b/xlators/mgmt/glusterd/src/glusterd.c
@@ -52,6 +52,12 @@ extern struct rpc_clnt_program glusterd3_1_mgmt_prog;
 extern struct rpcsvc_program gluster_pmap_prog;
 extern glusterd_op_info_t opinfo;
 
+rpcsvc_cbk_program_t glusterd_cbk_prog = {
+        .progname  = "Gluster Callback",
+        .prognum   = GLUSTER_CBK_PROGRAM,
+        .progver   = GLUSTER_CBK_VERSION,
+};
+
 
 static int
 glusterd_opinfo_init ()
@@ -100,7 +106,24 @@ glusterd_uuid_init ()
         return 0;
 }
 
+int
+glusterd_fetchspec_notify (xlator_t *this)
+{
+        int              ret   = -1;
+        glusterd_conf_t *priv  = NULL;
+        rpc_transport_t *trans = NULL;
+
+        priv = this->private;
 
+        list_for_each_entry (trans, &priv->xprt_list, list) {
+                rpcsvc_callback_submit (priv->rpc, trans, &glusterd_cbk_prog,
+                                        GF_CBK_FETCHSPEC, NULL, 0);
+        }
+
+        ret = 0;
+
+        return ret;
+}
 
 int
 glusterd_priv (xlator_t *this)
@@ -135,6 +158,7 @@ glusterd_rpcsvc_notify (rpcsvc_t *rpc, void *xl, rpcsvc_event_t event,
 {
         xlator_t            *this = NULL;
         rpc_transport_t     *xprt = NULL;
+        glusterd_conf_t     *priv = NULL;
 
         if (!xl || !data) {
                 gf_log ("glusterd", GF_LOG_WARNING,
@@ -145,13 +169,19 @@ glusterd_rpcsvc_notify (rpcsvc_t *rpc, void *xl, rpcsvc_event_t event,
         this = xl;
         xprt = data;
 
+        priv = this->private;
+
         switch (event) {
         case RPCSVC_EVENT_ACCEPT:
         {
+                INIT_LIST_HEAD (&xprt->list);
+
+                list_add_tail (&xprt->list, &priv->xprt_list);
                 break;
         }
         case RPCSVC_EVENT_DISCONNECT:
         {
+                list_del (&xprt->list);
                 pmap_registry_remove (this, 0, NULL, xprt);
                 break;
         }
@@ -328,11 +358,12 @@ init (xlator_t *this)
         conf->mgmt = &glusterd3_1_mgmt_prog;
         strncpy (conf->workdir, dirname, PATH_MAX);
 
+        INIT_LIST_HEAD (&conf->xprt_list);
+
         this->private = conf;
         //this->ctx->top = this;
 
         ret = glusterd_uuid_init ();
-
         if (ret < 0)
                 goto out;
 
@@ -390,22 +421,11 @@ int
 notify (xlator_t *this, int32_t event, void *data, ...)
 {
         int          ret = 0;
-        //transport_t *trans = data;
-        //peer_info_t *peerinfo = NULL;
-        //peer_info_t *myinfo = NULL;
 
-/*        if (trans != NULL) {
-                peerinfo = &(trans->peerinfo);
-                myinfo = &(trans->myinfo);
-        }
-*/
         switch (event) {
-
                 case GF_EVENT_POLLIN:
-          //              ret = glusterd_pollin (this, trans);
                         break;
 
-
                 case GF_EVENT_POLLERR:
                         break;
 
@@ -422,10 +442,6 @@ notify (xlator_t *this, int32_t event, void *data, ...)
 }
 
 
-
-//struct xlator_mops mops = {
-//};
-
 struct xlator_fops fops = {
 };
 
diff --git a/xlators/mgmt/glusterd/src/glusterd.h b/xlators/mgmt/glusterd/src/glusterd.h
index 0f2004779c8..f3e864a5f6e 100644
--- a/xlators/mgmt/glusterd/src/glusterd.h
+++ b/xlators/mgmt/glusterd/src/glusterd.h
@@ -69,6 +69,7 @@ typedef struct {
         struct pmap_registry *pmap;
         struct list_head  volumes;
         struct list_head  hostnames;
+        struct list_head  xprt_list;
         glusterd_store_handle_t *handle;
 } glusterd_conf_t;
 
@@ -337,4 +338,8 @@ glusterd_remove_brick (rpcsvc_request_t *req, dict_t *dict);
 int
 glusterd_xfer_cli_deprobe_resp (rpcsvc_request_t *req, int32_t op_ret,
                                 int32_t op_errno, char *hostname);
+
+int
+glusterd_fetchspec_notify (xlator_t *this);
+
 #endif
diff --git a/xlators/protocol/client/src/Makefile.am b/xlators/protocol/client/src/Makefile.am
index 159faf268a7..007810e9901 100644
--- a/xlators/protocol/client/src/Makefile.am
+++ b/xlators/protocol/client/src/Makefile.am
@@ -8,7 +8,8 @@ client_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la \
 	$(top_builddir)/rpc/rpc-lib/src/libgfrpc.la \
 	$(top_builddir)/rpc/xdr/src/libgfxdr.la
 
-client_la_SOURCES = client.c client-helpers.c client3_1-fops.c client-handshake.c
+client_la_SOURCES = client.c client-helpers.c client3_1-fops.c  \
+	client-handshake.c client-callback.c
 noinst_HEADERS = client.h client-mem-types.h
 
 AM_CFLAGS = -fPIC -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -Wall -D$(GF_HOST_OS) \
diff --git a/xlators/protocol/client/src/client-callback.c b/xlators/protocol/client/src/client-callback.c
new file mode 100644
index 00000000000..51bd3375845
--- /dev/null
+++ b/xlators/protocol/client/src/client-callback.c
@@ -0,0 +1,60 @@
+/*
+  Copyright (c) 2010 Gluster, Inc. <http://www.gluster.com>
+  This file is part of GlusterFS.
+
+  GlusterFS is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published
+  by the Free Software Foundation; either version 3 of the License,
+  or (at your option) any later version.
+
+  GlusterFS is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see
+  <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "client.h"
+#include "rpc-clnt.h"
+
+int
+client_cbk_null (void *data)
+{
+        return 0;
+}
+
+int
+client_cbk_fetchspec (void *data)
+{
+        gf_log ("", 1, "here i am");
+        return 0;
+}
+
+int
+client_cbk_ino_flush (void *data)
+{
+        return 0;
+}
+
+rpcclnt_cb_actor_t gluster_cbk_actors[] = {
+        [GF_CBK_NULL]      = {"NULL",      GF_CBK_NULL,      client_cbk_null },
+        [GF_CBK_FETCHSPEC] = {"FETCHSPEC", GF_CBK_FETCHSPEC, client_cbk_fetchspec },
+        [GF_CBK_INO_FLUSH] = {"INO_FLUSH", GF_CBK_INO_FLUSH, client_cbk_ino_flush },
+};
+
+
+struct rpcclnt_cb_program gluster_cbk_prog = {
+        .progname  = "GlusterFS Callback",
+        .prognum   = GLUSTER_CBK_PROGRAM,
+        .progver   = GLUSTER_CBK_VERSION,
+        .actors    = gluster_cbk_actors,
+        .numactors = GF_CBK_MAXVALUE,
+};
diff --git a/xlators/protocol/client/src/client.c b/xlators/protocol/client/src/client.c
index c840d96f54c..458ecfa8f88 100644
--- a/xlators/protocol/client/src/client.c
+++ b/xlators/protocol/client/src/client.c
@@ -34,6 +34,7 @@
 
 extern rpc_clnt_prog_t clnt_handshake_prog;
 extern rpc_clnt_prog_t clnt_dump_prog;
+extern struct rpcclnt_cb_program gluster_cbk_prog;
 
 int client_handshake (xlator_t *this, struct rpc_clnt *rpc);
 void client_start_ping (void *data);
@@ -1730,6 +1731,10 @@ client_init_rpc (xlator_t *this)
         conf->handshake = &clnt_handshake_prog;
         conf->dump      = &clnt_dump_prog;
 
+        ret = rpcclnt_cbk_program_register (conf->rpc, &gluster_cbk_prog);
+        if (ret)
+                goto out;
+
         ret = 0;
 
         gf_log (this->name, GF_LOG_DEBUG, "client init successful");
diff --git a/xlators/protocol/server/src/server.c b/xlators/protocol/server/src/server.c
index 262da3e3158..8a7d9da0bbf 100644
--- a/xlators/protocol/server/src/server.c
+++ b/xlators/protocol/server/src/server.c
@@ -123,6 +123,10 @@ server_submit_reply (call_frame_t *frame, rpcsvc_request_t *req, void *arg,
         ret = rpcsvc_submit_generic (req, &rsp, 1, payload, payloadcount,
                                      iobref);
 
+        /* TODO: this is demo purpose only */
+        /* ret = rpcsvc_callback_submit (req->svc, req->trans, req->prog,
+                                         GF_CBK_NULL, &rsp, 1);
+        */
         /* Now that we've done our job of handing the message to the RPC layer
          * we can safely unref the iob in the hope that RPC layer must have
          * ref'ed the iob on receiving into the txlist.
@@ -366,6 +370,7 @@ server_rpc_notify (rpcsvc_t *rpc, void *xl, rpcsvc_event_t event,
         xlator_t            *this = NULL;
         rpc_transport_t     *xprt = NULL;
         server_connection_t *conn = NULL;
+        server_conf_t       *conf = NULL;
 
 
         if (!xl || !data) {
@@ -376,6 +381,7 @@ server_rpc_notify (rpcsvc_t *rpc, void *xl, rpcsvc_event_t event,
 
         this = xl;
         xprt = data;
+        conf = this->private;
 
         switch (event) {
         case RPCSVC_EVENT_ACCEPT:
@@ -388,6 +394,10 @@ server_rpc_notify (rpcsvc_t *rpc, void *xl, rpcsvc_event_t event,
 
                 xprt->protocol_private = conn;
                 */
+                INIT_LIST_HEAD (&xprt->list);
+
+                list_add_tail (&xprt->list, &conf->xprt_list);
+
                 break;
         }
         case RPCSVC_EVENT_DISCONNECT:
@@ -395,6 +405,8 @@ server_rpc_notify (rpcsvc_t *rpc, void *xl, rpcsvc_event_t event,
                 if (conn)
                         server_connection_put (this, conn);
 
+                list_del (&xprt->list);
+
                 break;
         default:
                 break;
@@ -449,6 +461,7 @@ init (xlator_t *this)
         GF_VALIDATE_OR_GOTO(this->name, conf, out);
 
         INIT_LIST_HEAD (&conf->conns);
+        INIT_LIST_HEAD (&conf->xprt_list);
         pthread_mutex_init (&conf->mutex, NULL);
 
         this->private = conf;
diff --git a/xlators/protocol/server/src/server.h b/xlators/protocol/server/src/server.h
index 62e5ef886cf..b58e8a5fada 100644
--- a/xlators/protocol/server/src/server.h
+++ b/xlators/protocol/server/src/server.h
@@ -99,6 +99,7 @@ struct server_conf {
 	dict_t                 *auth_modules;
 	pthread_mutex_t         mutex;
 	struct list_head        conns;
+        struct list_head        xprt_list;
 };
 typedef struct server_conf server_conf_t;