glusterd: Volume locks and transaction specific opinfos

With this patch we are replacing the existing cluster-wide
lock taken on glusterds across the cluster, with volume locks
which are also taken on glusterds across the cluster, but are
volume specific. So with the volume locks we are able to perform
more than one gluster operation at the same time, as long as the
operations are being performed on different volumes.

We maintain a global list of volume-locks (using a dict for a list)
where the key is the volume name, and which saves the uuid of the
originator glusterd. These locks are held and released per volume
transaction.

In order to acheive multiple gluster operations occuring at the
same time, we also separate opinfos in the op-state-machine, as a
part of this patch. To do so, we generate a unique transaction-id
(uuid) per gluster transaction. An opinfo is then associated with
this transaction id, which is used throughout the transaction. We
maintain a run-time global list(using a dict) of transaction-ids,
and their respective opinfos to achieve this.

Upstream Feature Page: http://www.gluster.org/community/documentation/index.php/Features/glusterd-volume-locks

Change-Id: Iaad505a854bac8de8f83beec0357eb6cde3f7ea8
BUG: 1011470
Signed-off-by: Avra Sengupta <asengupt@redhat.com>
Reviewed-on: http://review.gluster.org/5994
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

18 files changed, 2047 insertions, 249 deletions

diff --git a/xlators/mgmt/glusterd/src/Makefile.am b/xlators/mgmt/glusterd/src/Makefile.am
index a6f49ae01b1..b109e6dff24 100644
--- a/xlators/mgmt/glusterd/src/Makefile.am
+++ b/xlators/mgmt/glusterd/src/Makefile.am
@@ -11,7 +11,8 @@ glusterd_la_SOURCES = glusterd.c glusterd-handler.c glusterd-sm.c \
 	glusterd-volgen.c glusterd-rebalance.c glusterd-quota.c \
 	glusterd-geo-rep.c glusterd-replace-brick.c glusterd-log-ops.c \
 	glusterd-volume-ops.c glusterd-brick-ops.c glusterd-mountbroker.c \
-	glusterd-syncop.c glusterd-hooks.c glusterd-volume-set.c
+	glusterd-syncop.c glusterd-hooks.c glusterd-volume-set.c \
+        glusterd-locks.c
 
 glusterd_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la \
 		     $(top_builddir)/rpc/xdr/src/libgfxdr.la \
@@ -21,7 +22,7 @@ glusterd_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la \
 noinst_HEADERS = glusterd.h glusterd-utils.h glusterd-op-sm.h \
 	glusterd-sm.h glusterd-store.h glusterd-mem-types.h \
 	glusterd-pmap.h glusterd-volgen.h glusterd-mountbroker.h \
-	glusterd-syncop.h glusterd-hooks.h
+	glusterd-syncop.h glusterd-hooks.h glusterd-locks.h
 
 AM_CPPFLAGS = $(GF_CPPFLAGS) -I$(top_srcdir)/libglusterfs/src \
 	-I$(rpclibdir) -I$(CONTRIBDIR)/rbtree \
diff --git a/xlators/mgmt/glusterd/src/glusterd-brick-ops.c b/xlators/mgmt/glusterd/src/glusterd-brick-ops.c
index 26d608a2f4c..ced916ea122 100644
--- a/xlators/mgmt/glusterd/src/glusterd-brick-ops.c
+++ b/xlators/mgmt/glusterd/src/glusterd-brick-ops.c
@@ -1467,7 +1467,7 @@ glusterd_op_stage_remove_brick (dict_t *dict, char **op_errstr)
                         goto out;
                 }
 
-                if (is_origin_glusterd ()) {
+                if (is_origin_glusterd (dict)) {
                         ret = glusterd_generate_and_set_task_id
                                 (dict, GF_REMOVE_BRICK_TID_KEY);
                         if (ret) {
@@ -1733,7 +1733,7 @@ glusterd_op_remove_brick (dict_t *dict, char **op_errstr)
         /* Set task-id, if available, in ctx dict for operations other than
          * start
          */
-        if (is_origin_glusterd () && (cmd != GF_OP_CMD_START)) {
+        if (is_origin_glusterd (dict) && (cmd != GF_OP_CMD_START)) {
                 if (!uuid_is_null (volinfo->rebal.rebalance_id)) {
                         ret = glusterd_copy_uuid_to_dict
                                 (volinfo->rebal.rebalance_id, dict,
diff --git a/xlators/mgmt/glusterd/src/glusterd-handler.c b/xlators/mgmt/glusterd/src/glusterd-handler.c
index ab3fa94c0fa..797141decd1 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handler.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handler.c
@@ -33,6 +33,7 @@
 #include "glusterd-op-sm.h"
 #include "glusterd-utils.h"
 #include "glusterd-store.h"
+#include "glusterd-locks.h"
 
 #include "glusterd1-xdr.h"
 #include "cli1-xdr.h"
@@ -55,6 +56,7 @@
 #endif
 
 extern glusterd_op_info_t opinfo;
+extern uuid_t global_txn_id;
 
 int glusterd_big_locked_notify (struct rpc_clnt *rpc, void *mydata,
                                 rpc_clnt_event_t event,
@@ -590,10 +592,16 @@ int32_t
 glusterd_op_txn_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx,
                        char *err_str, size_t err_len)
 {
-        int32_t                  ret    = -1;
-        xlator_t                *this   = NULL;
-        glusterd_conf_t         *priv   = NULL;
-        int32_t                  locked = 0;
+        int32_t                     ret             = -1;
+        dict_t                     *dict            = NULL;
+        xlator_t                   *this            = NULL;
+        glusterd_conf_t            *priv            = NULL;
+        int32_t                     locked          = 0;
+        char                       *tmp             = NULL;
+        char                       *volname         = NULL;
+        uuid_t                     *txn_id          = NULL;
+        glusterd_op_info_t          txn_op_info     = {{0},};
+        glusterd_op_sm_event_type_t event_type      = GD_OP_EVENT_NONE;
 
         GF_ASSERT (req);
         GF_ASSERT ((op > GD_OP_NONE) && (op < GD_OP_MAX));
@@ -604,33 +612,122 @@ glusterd_op_txn_begin (rpcsvc_request_t *req, glusterd_op_t op, void *ctx,
         priv = this->private;
         GF_ASSERT (priv);
 
-        ret = glusterd_lock (MY_UUID);
+        dict = ctx;
+
+        /* Generate a transaction-id for this operation and
+         * save it in the dict. This transaction id distinguishes
+         * each transaction, and helps separate opinfos in the
+         * op state machine. */
+        ret = glusterd_generate_txn_id (dict, &txn_id);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to generate transaction id");
+                goto out;
+
+        }
+
+        /* Save the MY_UUID as the originator_uuid. This originator_uuid
+         * will be used by is_origin_glusterd() to determine if a node
+         * is the originator node for a command. */
+        ret = glusterd_set_originator_uuid (dict);
         if (ret) {
                 gf_log (this->name, GF_LOG_ERROR,
-                        "Unable to acquire lock on localhost, ret: %d", ret);
-                snprintf (err_str, err_len, "Another transaction is in progress. "
-                          "Please try again after sometime.");
+                        "Failed to set originator_uuid.");
                 goto out;
         }
 
+        /* Based on the op_version, acquire a cluster or volume lock */
+        if (priv->op_version < GD_OP_VERSION_4) {
+                ret = glusterd_lock (MY_UUID);
+                if (ret) {
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to acquire lock on localhost, ret: %d",
+                                ret);
+                        snprintf (err_str, err_len,
+                                  "Another transaction is in progress. "
+                                  "Please try again after sometime.");
+                        goto out;
+                }
+        } else {
+                /* If no volname is given as a part of the command, locks will
+                 * not be held */
+                ret = dict_get_str (dict, "volname", &tmp);
+                if (ret) {
+                        gf_log ("", GF_LOG_INFO,
+                                "No Volume name present. "
+                                "Locks not being held.");
+                        goto local_locking_done;
+                } else {
+                        /* Use a copy of volname, as cli response will be
+                         * sent before the unlock, and the volname in the
+                         * dict, might be removed */
+                        volname = gf_strdup (tmp);
+                        if (!volname)
+                                goto out;
+                }
+
+                ret = glusterd_volume_lock (volname, MY_UUID);
+                if (ret) {
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to acquire lock for %s", volname);
+                        snprintf (err_str, err_len,
+                                  "Another transaction is in progress for %s. "
+                                  "Please try again after sometime.", volname);
+                        goto out;
+                }
+        }
+
         locked = 1;
         gf_log (this->name, GF_LOG_DEBUG, "Acquired lock on localhost");
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_START_LOCK, NULL);
+local_locking_done:
+
+        /* If no volname is given as a part of the command, locks will
+         * not be held, hence sending stage event. */
+        if (volname)
+                event_type = GD_OP_EVENT_START_LOCK;
+        else {
+                txn_op_info.state.state = GD_OP_STATE_LOCK_SENT;
+                event_type = GD_OP_EVENT_ALL_ACC;
+        }
+
+        /* Save opinfo for this transaction with the transaction id */
+        glusterd_txn_opinfo_init (&txn_op_info, NULL, &op, ctx, req);
+
+        ret = glusterd_set_txn_opinfo (txn_id, &txn_op_info);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to set transaction's opinfo");
+                if (ctx)
+                        dict_unref (ctx);
+                goto out;
+        }
+
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, ctx);
         if (ret) {
                 gf_log (this->name, GF_LOG_ERROR, "Failed to acquire cluster"
                         " lock.");
                 goto out;
         }
 
-        glusterd_op_set_op (op);
-        glusterd_op_set_ctx (ctx);
-        glusterd_op_set_req (req);
-
-
 out:
-        if (locked && ret)
-                glusterd_unlock (MY_UUID);
+        if (locked && ret) {
+                /* Based on the op-version, we release the
+                 * cluster or volume lock */
+                if (priv->op_version < GD_OP_VERSION_4)
+                        glusterd_unlock (MY_UUID);
+                else {
+                        ret = glusterd_volume_unlock (volname, MY_UUID);
+                        if (ret)
+                                gf_log (this->name, GF_LOG_ERROR,
+                                        "Unable to release lock for %s",
+                                        volname);
+                        ret = -1;
+                }
+        }
+
+        if (volname)
+                GF_FREE (volname);
 
         gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
         return ret;
@@ -639,11 +736,15 @@ out:
 int
 __glusterd_handle_cluster_lock (rpcsvc_request_t *req)
 {
-        gd1_mgmt_cluster_lock_req       lock_req = {{0},};
-        int32_t                         ret = -1;
-        glusterd_op_lock_ctx_t          *ctx = NULL;
-        glusterd_peerinfo_t             *peerinfo = NULL;
-        xlator_t                        *this = NULL;
+        dict_t                         *op_ctx      = NULL;
+        int32_t                         ret         = -1;
+        gd1_mgmt_cluster_lock_req       lock_req    = {{0},};
+        glusterd_op_lock_ctx_t         *ctx         = NULL;
+        glusterd_op_t                   op          = GD_OP_EVENT_LOCK;
+        glusterd_peerinfo_t            *peerinfo    = NULL;
+        glusterd_op_info_t              txn_op_info = {{0},};
+        uuid_t                         *txn_id      = &global_txn_id;
+        xlator_t                       *this        = NULL;
 
         this = THIS;
         GF_ASSERT (this);
@@ -678,8 +779,29 @@ __glusterd_handle_cluster_lock (rpcsvc_request_t *req)
 
         uuid_copy (ctx->uuid, lock_req.uuid);
         ctx->req = req;
+        ctx->dict = NULL;
+
+        op_ctx =  dict_new ();
+        if (!op_ctx) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to set new dict");
+                goto out;
+        }
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_LOCK, ctx);
+        glusterd_txn_opinfo_init (&txn_op_info, NULL, &op, op_ctx, req);
+
+        ret = glusterd_set_txn_opinfo (txn_id, &txn_op_info);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to set transaction's opinfo");
+                dict_unref (txn_op_info.op_ctx);
+                goto out;
+        }
+
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_LOCK, txn_id, ctx);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to inject event GD_OP_EVENT_LOCK");
 
 out:
         gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
@@ -697,6 +819,186 @@ glusterd_handle_cluster_lock (rpcsvc_request_t *req)
                                             __glusterd_handle_cluster_lock);
 }
 
+static int
+glusterd_handle_volume_lock_fn (rpcsvc_request_t *req)
+{
+        gd1_mgmt_volume_lock_req        lock_req    = {{0},};
+        int32_t                         ret         = -1;
+        glusterd_op_lock_ctx_t         *ctx         = NULL;
+        glusterd_peerinfo_t            *peerinfo    = NULL;
+        xlator_t                       *this        = NULL;
+        glusterd_op_info_t              txn_op_info = {{0},};
+
+        this = THIS;
+        GF_ASSERT (this);
+        GF_ASSERT (req);
+
+        ret = xdr_to_generic (req->msg[0], &lock_req,
+                              (xdrproc_t)xdr_gd1_mgmt_volume_lock_req);
+        if (ret < 0) {
+                gf_log (this->name, GF_LOG_ERROR, "Failed to decode lock "
+                        "request received from peer");
+                req->rpc_err = GARBAGE_ARGS;
+                goto out;
+        }
+
+        gf_log (this->name, GF_LOG_DEBUG, "Received volume lock req "
+                "from uuid: %s txn_id: %s", uuid_utoa (lock_req.uuid),
+                uuid_utoa (lock_req.txn_id));
+
+        if (glusterd_friend_find_by_uuid (lock_req.uuid, &peerinfo)) {
+                gf_log (this->name, GF_LOG_WARNING, "%s doesn't "
+                        "belong to the cluster. Ignoring request.",
+                        uuid_utoa (lock_req.uuid));
+                ret = -1;
+                goto out;
+        }
+
+        ctx = GF_CALLOC (1, sizeof (*ctx), gf_gld_mt_op_lock_ctx_t);
+        if (!ctx) {
+                ret = -1;
+                goto out;
+        }
+
+        uuid_copy (ctx->uuid, lock_req.uuid);
+        ctx->req = req;
+
+        ctx->dict = dict_new ();
+        if (!ctx->dict) {
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_unserialize (lock_req.dict.dict_val,
+                                lock_req.dict.dict_len, &ctx->dict);
+        if (ret) {
+                gf_log (this->name, GF_LOG_WARNING,
+                        "failed to unserialize the dictionary");
+                goto out;
+        }
+
+        glusterd_txn_opinfo_init (&txn_op_info, NULL, &lock_req.op,
+                                  ctx->dict, req);
+
+        ret = glusterd_set_txn_opinfo (&lock_req.txn_id, &txn_op_info);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to set transaction's opinfo");
+                goto out;
+        }
+
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_LOCK,
+                                           &lock_req.txn_id, ctx);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to inject event GD_OP_EVENT_LOCK");
+
+out:
+        if (ret) {
+                if (ctx->dict)
+                        dict_destroy (ctx->dict);
+                if (ctx)
+                        GF_FREE (ctx);
+        }
+
+        glusterd_friend_sm ();
+        glusterd_op_sm ();
+
+        gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int
+glusterd_handle_volume_lock (rpcsvc_request_t *req)
+{
+        return glusterd_big_locked_handler (req,
+                                            glusterd_handle_volume_lock_fn);
+}
+
+static int
+glusterd_handle_volume_unlock_fn (rpcsvc_request_t *req)
+{
+        gd1_mgmt_volume_unlock_req        lock_req = {{0},};
+        int32_t                           ret      = -1;
+        glusterd_op_lock_ctx_t           *ctx      = NULL;
+        glusterd_peerinfo_t              *peerinfo = NULL;
+        xlator_t                         *this     = NULL;
+
+        this = THIS;
+        GF_ASSERT (this);
+        GF_ASSERT (req);
+
+        ret = xdr_to_generic (req->msg[0], &lock_req,
+                              (xdrproc_t)xdr_gd1_mgmt_volume_unlock_req);
+        if (ret < 0) {
+                gf_log (this->name, GF_LOG_ERROR, "Failed to decode unlock "
+                        "request received from peer");
+                req->rpc_err = GARBAGE_ARGS;
+                goto out;
+        }
+
+        gf_log (this->name, GF_LOG_DEBUG, "Received volume unlock req "
+                "from uuid: %s", uuid_utoa (lock_req.uuid));
+
+        if (glusterd_friend_find_by_uuid (lock_req.uuid, &peerinfo)) {
+                gf_log (this->name, GF_LOG_WARNING, "%s doesn't "
+                        "belong to the cluster. Ignoring request.",
+                        uuid_utoa (lock_req.uuid));
+                ret = -1;
+                goto out;
+        }
+
+        ctx = GF_CALLOC (1, sizeof (*ctx), gf_gld_mt_op_lock_ctx_t);
+        if (!ctx) {
+                ret = -1;
+                goto out;
+        }
+
+        uuid_copy (ctx->uuid, lock_req.uuid);
+        ctx->req = req;
+
+        ctx->dict = dict_new ();
+        if (!ctx->dict) {
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_unserialize (lock_req.dict.dict_val,
+                                lock_req.dict.dict_len, &ctx->dict);
+        if (ret) {
+                gf_log (this->name, GF_LOG_WARNING,
+                        "failed to unserialize the dictionary");
+                goto out;
+        }
+
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_UNLOCK,
+                                           &lock_req.txn_id, ctx);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to inject event GD_OP_EVENT_UNLOCK");
+
+out:
+        if (ret) {
+                if (ctx->dict)
+                        dict_destroy (ctx->dict);
+                if (ctx)
+                        GF_FREE (ctx);
+        }
+
+        glusterd_friend_sm ();
+        glusterd_op_sm ();
+
+        gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int
+glusterd_handle_volume_unlock (rpcsvc_request_t *req)
+{
+        return glusterd_big_locked_handler (req,
+                                            glusterd_handle_volume_unlock_fn);
+}
+
 int
 glusterd_req_ctx_create (rpcsvc_request_t *rpc_req,
                          glusterd_op_t op, uuid_t uuid,
@@ -755,6 +1057,9 @@ __glusterd_handle_stage_op (rpcsvc_request_t *req)
         gd1_mgmt_stage_op_req           op_req = {{0},};
         glusterd_peerinfo_t             *peerinfo = NULL;
         xlator_t                        *this = NULL;
+        uuid_t                          *txn_id = &global_txn_id;
+        glusterd_op_info_t              txn_op_info = {{0},};
+        glusterd_op_sm_state_info_t     state = {0,};
 
         this = THIS;
         GF_ASSERT (this);
@@ -783,7 +1088,36 @@ __glusterd_handle_stage_op (rpcsvc_request_t *req)
         if (ret)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_STAGE_OP, req_ctx);
+        ret = dict_get_bin (req_ctx->dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
+
+        /* In cases where there is no volname, the receivers won't have a
+         * transaction opinfo created, as for those operations, the locking
+         * phase where the transaction opinfos are created, won't be called. */
+        ret = glusterd_get_txn_opinfo (txn_id, &txn_op_info);
+        if (ret) {
+                gf_log (this->name, GF_LOG_DEBUG,
+                        "No transaction's opinfo set");
+
+                state.state = GD_OP_STATE_LOCKED;
+                glusterd_txn_opinfo_init (&txn_op_info, &state,
+                                          &op_req.op, req_ctx->dict, req);
+
+                ret = glusterd_set_txn_opinfo (txn_id, &txn_op_info);
+                if (ret) {
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to set transaction's opinfo");
+                        dict_unref (req_ctx->dict);
+                        goto out;
+                }
+        }
+
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_STAGE_OP,
+                                           txn_id, req_ctx);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to inject event GD_OP_EVENT_STAGE_OP");
 
  out:
         free (op_req.buf.buf_val);//malloced by xdr
@@ -807,6 +1141,7 @@ __glusterd_handle_commit_op (rpcsvc_request_t *req)
         gd1_mgmt_commit_op_req          op_req = {{0},};
         glusterd_peerinfo_t             *peerinfo = NULL;
         xlator_t                        *this = NULL;
+        uuid_t                          *txn_id = &global_txn_id;
 
         this = THIS;
         GF_ASSERT (this);
@@ -837,11 +1172,12 @@ __glusterd_handle_commit_op (rpcsvc_request_t *req)
         if (ret)
                 goto out;
 
-        ret = glusterd_op_init_ctx (op_req.op);
-        if (ret)
-                goto out;
+        ret = dict_get_bin (req_ctx->dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_COMMIT_OP, req_ctx);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_COMMIT_OP,
+                                           txn_id, req_ctx);
 
 out:
         free (op_req.buf.buf_val);//malloced by xdr
@@ -1892,6 +2228,56 @@ glusterd_op_unlock_send_resp (rpcsvc_request_t *req, int32_t status)
 }
 
 int
+glusterd_op_volume_lock_send_resp (rpcsvc_request_t *req, uuid_t *txn_id,
+                                   int32_t status)
+{
+
+        gd1_mgmt_volume_lock_rsp       rsp = {{0},};
+        int                            ret = -1;
+
+        GF_ASSERT (req);
+        GF_ASSERT (txn_id);
+        glusterd_get_uuid (&rsp.uuid);
+        rsp.op_ret = status;
+        if (rsp.op_ret)
+               rsp.op_errno = errno;
+        uuid_copy (rsp.txn_id, *txn_id);
+
+        ret = glusterd_submit_reply (req, &rsp, NULL, 0, NULL,
+                                     (xdrproc_t)xdr_gd1_mgmt_volume_lock_rsp);
+
+        gf_log (THIS->name, GF_LOG_DEBUG, "Responded to volume lock, ret: %d",
+                ret);
+
+        return ret;
+}
+
+int
+glusterd_op_volume_unlock_send_resp (rpcsvc_request_t *req, uuid_t *txn_id,
+                                     int32_t status)
+{
+
+        gd1_mgmt_volume_unlock_rsp      rsp = {{0},};
+        int                             ret = -1;
+
+        GF_ASSERT (req);
+        GF_ASSERT (txn_id);
+        rsp.op_ret = status;
+        if (rsp.op_ret)
+               rsp.op_errno = errno;
+        glusterd_get_uuid (&rsp.uuid);
+        uuid_copy (rsp.txn_id, *txn_id);
+
+        ret = glusterd_submit_reply (req, &rsp, NULL, 0, NULL,
+                                     (xdrproc_t)xdr_gd1_mgmt_volume_unlock_rsp);
+
+        gf_log (THIS->name, GF_LOG_DEBUG, "Responded to volume unlock, ret: %d",
+                ret);
+
+        return ret;
+}
+
+int
 __glusterd_handle_cluster_unlock (rpcsvc_request_t *req)
 {
         gd1_mgmt_cluster_unlock_req     unlock_req = {{0}, };
@@ -1899,6 +2285,7 @@ __glusterd_handle_cluster_unlock (rpcsvc_request_t *req)
         glusterd_op_lock_ctx_t          *ctx = NULL;
         glusterd_peerinfo_t             *peerinfo = NULL;
         xlator_t                        *this = NULL;
+        uuid_t                          *txn_id = &global_txn_id;
 
         this = THIS;
         GF_ASSERT (this);
@@ -1933,8 +2320,9 @@ __glusterd_handle_cluster_unlock (rpcsvc_request_t *req)
         }
         uuid_copy (ctx->uuid, unlock_req.uuid);
         ctx->req = req;
+        ctx->dict = NULL;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_UNLOCK, ctx);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_UNLOCK, txn_id, ctx);
 
 out:
         glusterd_friend_sm ();
@@ -3838,6 +4226,7 @@ __glusterd_peer_rpc_notify (struct rpc_clnt *rpc, void *mydata,
         glusterd_peerinfo_t  *peerinfo    = NULL;
         glusterd_peerctx_t   *peerctx     = NULL;
         gf_boolean_t         quorum_action = _gf_false;
+        glusterd_volinfo_t   *volinfo     = NULL;
         uuid_t               uuid;
 
         peerctx = mydata;
@@ -3866,6 +4255,30 @@ __glusterd_peer_rpc_notify (struct rpc_clnt *rpc, void *mydata,
                 gf_log (this->name, GF_LOG_DEBUG, "got RPC_CLNT_DISCONNECT %d",
                         peerinfo->state.state);
 
+                if (peerinfo->connected) {
+                        if (conf->op_version < GD_OP_VERSION_4) {
+                                glusterd_get_lock_owner (&uuid);
+                                if (!uuid_is_null (uuid) &&
+                                    !uuid_compare (peerinfo->uuid, uuid))
+                                        glusterd_unlock (peerinfo->uuid);
+                        } else {
+                                list_for_each_entry (volinfo, &conf->volumes,
+                                                     vol_list) {
+                                        ret = glusterd_volume_unlock
+                                                    (volinfo->volname,
+                                                     peerinfo->uuid);
+                                        if (ret)
+                                                gf_log (this->name,
+                                                        GF_LOG_TRACE,
+                                                        "Lock not released "
+                                                        "for %s",
+                                                         volinfo->volname);
+                                }
+                        }
+
+                        ret = 0;
+                }
+
                 if ((peerinfo->quorum_contrib != QUORUM_DOWN) &&
                     (peerinfo->state.state == GD_FRIEND_STATE_BEFRIENDED)) {
                         peerinfo->quorum_contrib = QUORUM_DOWN;
@@ -3880,13 +4293,6 @@ __glusterd_peer_rpc_notify (struct rpc_clnt *rpc, void *mydata,
                         glusterd_friend_remove_notify (peerctx);
                         goto out;
                 }
-                glusterd_get_lock_owner (&uuid);
-                if (!uuid_is_null (uuid) &&
-                    !uuid_compare (peerinfo->uuid, uuid)) {
-                        glusterd_unlock (peerinfo->uuid);
-                        if (opinfo.state.state != GD_OP_STATE_DEFAULT)
-                                opinfo.state.state = GD_OP_STATE_DEFAULT;
-                }
 
                 peerinfo->connected = 0;
                 break;
@@ -4021,3 +4427,18 @@ struct rpcsvc_program gd_svc_cli_prog_ro = {
         .actors    = gd_svc_cli_actors_ro,
 	.synctask  = _gf_true,
 };
+
+rpcsvc_actor_t gd_svc_mgmt_v3_actors[] = {
+        [GLUSTERD_MGMT_V3_NULL]          = { "NULL",       GLUSTERD_MGMT_V3_NULL,          glusterd_null,                 NULL, 0, DRC_NA},
+        [GLUSTERD_MGMT_V3_VOLUME_LOCK]   = { "VOL_LOCK",   GLUSTERD_MGMT_V3_VOLUME_LOCK,   glusterd_handle_volume_lock,   NULL, 0, DRC_NA},
+        [GLUSTERD_MGMT_V3_VOLUME_UNLOCK] = { "VOL_UNLOCK", GLUSTERD_MGMT_V3_VOLUME_UNLOCK, glusterd_handle_volume_unlock, NULL, 0, DRC_NA},
+};
+
+struct rpcsvc_program gd_svc_mgmt_v3_prog = {
+        .progname  = "GlusterD svc mgmt v3",
+        .prognum   = GD_MGMT_PROGRAM,
+        .progver   = GD_MGMT_V3_VERSION,
+        .numactors = GLUSTERD_MGMT_V3_MAXVALUE,
+        .actors    = gd_svc_mgmt_v3_actors,
+        .synctask  = _gf_true,
+};
diff --git a/xlators/mgmt/glusterd/src/glusterd-handshake.c b/xlators/mgmt/glusterd/src/glusterd-handshake.c
index 1420eb692ee..e0508faf62b 100644
--- a/xlators/mgmt/glusterd/src/glusterd-handshake.c
+++ b/xlators/mgmt/glusterd/src/glusterd-handshake.c
@@ -30,6 +30,7 @@
 
 extern struct rpc_clnt_program gd_peer_prog;
 extern struct rpc_clnt_program gd_mgmt_prog;
+extern struct rpc_clnt_program gd_mgmt_v3_prog;
 
 #define TRUSTED_PREFIX         "trusted-"
 
@@ -812,6 +813,7 @@ __glusterd_mgmt_hndsk_version_ack_cbk (struct rpc_req *req, struct iovec *iov,
          */
         peerinfo->mgmt = &gd_mgmt_prog;
         peerinfo->peer = &gd_peer_prog;
+        peerinfo->mgmt_v3 = &gd_mgmt_v3_prog;
 
         ret = default_notify (this, GF_EVENT_CHILD_UP, NULL);
 
@@ -1038,6 +1040,15 @@ glusterd_set_clnt_mgmt_program (glusterd_peerinfo_t *peerinfo,
                          peerinfo->peer->progname, peerinfo->peer->prognum,
                          peerinfo->peer->progver);
         }
+
+        if (peerinfo->mgmt_v3) {
+                 gf_log ("", GF_LOG_INFO,
+                         "Using Program %s, Num (%d), Version (%d)",
+                         peerinfo->mgmt_v3->progname,
+                         peerinfo->mgmt_v3->prognum,
+                         peerinfo->mgmt_v3->progver);
+        }
+
         ret = 0;
 out:
         return ret;
diff --git a/xlators/mgmt/glusterd/src/glusterd-locks.c b/xlators/mgmt/glusterd/src/glusterd-locks.c
new file mode 100644
index 00000000000..68c6d74264b
--- /dev/null
+++ b/xlators/mgmt/glusterd/src/glusterd-locks.c
@@ -0,0 +1,177 @@
+/*
+   Copyright (c) 2013-2014 Red Hat, Inc. <http://www.redhat.com>
+   This file is part of GlusterFS.
+
+   This file is licensed to you under your choice of the GNU Lesser
+   General Public License, version 3 or any later version (LGPLv3 or
+   later), or the GNU General Public License, version 2 (GPLv2), in all
+   cases as published by the Free Software Foundation.
+*/
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "common-utils.h"
+#include "cli1-xdr.h"
+#include "xdr-generic.h"
+#include "glusterd.h"
+#include "glusterd-op-sm.h"
+#include "glusterd-store.h"
+#include "glusterd-utils.h"
+#include "glusterd-volgen.h"
+#include "glusterd-locks.h"
+#include "run.h"
+#include "syscall.h"
+
+#include <signal.h>
+
+static dict_t *vol_lock;
+
+/* Initialize the global vol-lock list(dict) when
+ * glusterd is spawned */
+int32_t
+glusterd_vol_lock_init ()
+{
+        int32_t ret = -1;
+
+        vol_lock = dict_new ();
+        if (!vol_lock)
+                goto out;
+
+        ret = 0;
+out:
+        return ret;
+}
+
+/* Destroy the global vol-lock list(dict) when
+ * glusterd cleanup is performed */
+void
+glusterd_vol_lock_fini ()
+{
+        if (vol_lock)
+                dict_unref (vol_lock);
+}
+
+int32_t
+glusterd_get_vol_lock_owner (char *volname, uuid_t *uuid)
+{
+        int32_t        ret      = -1;
+        vol_lock_obj  *lock_obj = NULL;
+        uuid_t         no_owner = {0,};
+
+        if (!volname || !uuid) {
+                gf_log ("", GF_LOG_ERROR, "volname or uuid is null.");
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_get_bin (vol_lock, volname, (void **) &lock_obj);
+        if (!ret)
+                uuid_copy (*uuid, lock_obj->lock_owner);
+        else
+                uuid_copy (*uuid, no_owner);
+
+        ret = 0;
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
+glusterd_volume_lock (char *volname, uuid_t uuid)
+{
+        int32_t        ret      = -1;
+        vol_lock_obj  *lock_obj = NULL;
+        uuid_t         owner    = {0};
+
+        if (!volname) {
+                gf_log ("", GF_LOG_ERROR, "volname is null.");
+                ret = -1;
+                goto out;
+        }
+
+        ret = glusterd_get_vol_lock_owner (volname, &owner);
+        if (ret) {
+                gf_log ("", GF_LOG_DEBUG, "Unable to get volume lock owner");
+                goto out;
+        }
+
+        /* If the lock has already been held for the given volume
+         * we fail */
+        if (!uuid_is_null (owner)) {
+                gf_log ("", GF_LOG_ERROR, "Unable to acquire lock. "
+                        "Lock for %s held by %s", volname,
+                        uuid_utoa (owner));
+                ret = -1;
+                goto out;
+        }
+
+        lock_obj = GF_CALLOC (1, sizeof(vol_lock_obj),
+                              gf_common_mt_vol_lock_obj_t);
+        if (!lock_obj) {
+                ret = -1;
+                goto out;
+        }
+
+        uuid_copy (lock_obj->lock_owner, uuid);
+
+        ret = dict_set_bin (vol_lock, volname, lock_obj, sizeof(vol_lock_obj));
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR, "Unable to set lock owner "
+                                          "in volume lock");
+                if (lock_obj)
+                        GF_FREE (lock_obj);
+                goto out;
+        }
+
+        gf_log ("", GF_LOG_DEBUG, "Lock for %s successfully held by %s",
+                volname, uuid_utoa (uuid));
+
+        ret = 0;
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
+glusterd_volume_unlock (char *volname, uuid_t uuid)
+{
+        int32_t        ret      = -1;
+        uuid_t         owner    = {0};
+
+        if (!volname) {
+                gf_log ("", GF_LOG_ERROR, "volname is null.");
+                ret = -1;
+                goto out;
+        }
+
+        ret = glusterd_get_vol_lock_owner (volname, &owner);
+        if (ret)
+                goto out;
+
+        if (uuid_is_null (owner)) {
+                gf_log ("", GF_LOG_ERROR, "Lock for %s not held", volname);
+                ret = -1;
+                goto out;
+        }
+
+        ret = uuid_compare (uuid, owner);
+        if (ret) {
+                gf_log (THIS->name, GF_LOG_ERROR, "Lock owner mismatch. "
+                        "Lock for %s held by %s",
+                        volname, uuid_utoa (owner));
+                goto out;
+        }
+
+        /* Removing the volume lock from the global list */
+        dict_del (vol_lock, volname);
+
+        gf_log ("", GF_LOG_DEBUG, "Lock for %s successfully released",
+                volname);
+
+        ret = 0;
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
diff --git a/xlators/mgmt/glusterd/src/glusterd-locks.h b/xlators/mgmt/glusterd/src/glusterd-locks.h
new file mode 100644
index 00000000000..2a8cc20ed25
--- /dev/null
+++ b/xlators/mgmt/glusterd/src/glusterd-locks.h
@@ -0,0 +1,38 @@
+/*
+   Copyright (c) 2013-2014 Red Hat, Inc. <http://www.redhat.com>
+   This file is part of GlusterFS.
+
+   This file is licensed to you under your choice of the GNU Lesser
+   General Public License, version 3 or any later version (LGPLv3 or
+   later), or the GNU General Public License, version 2 (GPLv2), in all
+   cases as published by the Free Software Foundation.
+*/
+#ifndef _GLUSTERD_LOCKS_H_
+#define _GLUSTERD_LOCKS_H_
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+struct volume_lock_object_ {
+        uuid_t              lock_owner;
+};
+typedef struct volume_lock_object_ vol_lock_obj;
+
+int32_t
+glusterd_vol_lock_init ();
+
+void
+glusterd_vol_lock_fini ();
+
+int32_t
+glusterd_get_vol_lock_owner (char *volname, uuid_t *uuid);
+
+int32_t
+glusterd_volume_lock (char *volname, uuid_t uuid);
+
+int32_t
+glusterd_volume_unlock (char *volname, uuid_t uuid);
+
+#endif
diff --git a/xlators/mgmt/glusterd/src/glusterd-op-sm.c b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
index 5758e217df9..83c91a52d1d 100644
--- a/xlators/mgmt/glusterd/src/glusterd-op-sm.c
+++ b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
@@ -37,6 +37,7 @@
 #include "glusterd-store.h"
 #include "glusterd-hooks.h"
 #include "glusterd-volgen.h"
+#include "glusterd-locks.h"
 #include "syscall.h"
 #include "cli1-xdr.h"
 #include "common-utils.h"
@@ -67,6 +68,195 @@
 static struct list_head gd_op_sm_queue;
 pthread_mutex_t       gd_op_sm_lock;
 glusterd_op_info_t    opinfo = {{0},};
+uuid_t                global_txn_id = {0}; /* To be used in
+                                               * heterogeneous
+                                               * cluster with no
+                                               * transaction ids */
+
+static dict_t *txn_opinfo;
+
+struct glusterd_txn_opinfo_object_ {
+        glusterd_op_info_t    opinfo;
+};
+typedef struct glusterd_txn_opinfo_object_ glusterd_txn_opinfo_obj;
+
+int32_t
+glusterd_txn_opinfo_dict_init ()
+{
+        int32_t ret = -1;
+
+        txn_opinfo = dict_new ();
+        if (!txn_opinfo) {
+                ret = -1;
+                goto out;
+        }
+
+        ret = 0;
+out:
+        return ret;
+}
+
+void
+glusterd_txn_opinfo_dict_fini ()
+{
+        if (txn_opinfo)
+                dict_destroy (txn_opinfo);
+}
+
+void
+glusterd_txn_opinfo_init (glusterd_op_info_t  *opinfo,
+                          glusterd_op_sm_state_info_t *state,
+                          glusterd_op_t *op,
+                          dict_t *op_ctx,
+                          rpcsvc_request_t *req)
+{
+        GF_ASSERT (opinfo);
+
+        if (state)
+                opinfo->state = *state;
+
+        if (op)
+                opinfo->op = *op;
+
+        opinfo->op_ctx = dict_ref(op_ctx);
+
+        if (req)
+                opinfo->req = req;
+
+        return;
+}
+
+int32_t
+glusterd_generate_txn_id (dict_t *dict, uuid_t **txn_id)
+{
+        int32_t             ret      = -1;
+
+        GF_ASSERT (dict);
+
+        *txn_id = GF_CALLOC (1, sizeof(uuid_t), gf_common_mt_uuid_t);
+        if (!*txn_id)
+                goto out;
+
+        uuid_generate (**txn_id);
+
+        ret = dict_set_bin (dict, "transaction_id",
+                            *txn_id, sizeof (uuid_t));
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR,
+                       "Failed to set transaction id.");
+                goto out;
+        }
+
+        gf_log ("", GF_LOG_DEBUG,
+                "Transaction_id = %s", uuid_utoa (**txn_id));
+out:
+        if (ret && *txn_id)
+                GF_FREE (*txn_id);
+
+        return ret;
+}
+
+int32_t
+glusterd_get_txn_opinfo (uuid_t *txn_id, glusterd_op_info_t  *opinfo)
+{
+        int32_t                   ret         = -1;
+        glusterd_txn_opinfo_obj  *opinfo_obj  = NULL;
+
+        if (!txn_id || !opinfo) {
+                gf_log ("", GF_LOG_ERROR,
+                        "Empty transaction id or opinfo received.");
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_get_bin(txn_opinfo, uuid_utoa (*txn_id),
+                           (void **) &opinfo_obj);
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR,
+                        "Unable to get transaction opinfo");
+                goto out;
+        }
+
+        (*opinfo) = opinfo_obj->opinfo;
+
+        ret = 0;
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
+glusterd_set_txn_opinfo (uuid_t *txn_id, glusterd_op_info_t  *opinfo)
+{
+        int32_t                   ret        = -1;
+        glusterd_txn_opinfo_obj  *opinfo_obj = NULL;
+
+        if (!txn_id) {
+                gf_log ("", GF_LOG_ERROR, "Empty transaction id received.");
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_get_bin(txn_opinfo, uuid_utoa (*txn_id),
+                           (void **) &opinfo_obj);
+        if (ret) {
+                opinfo_obj = GF_CALLOC (1, sizeof(glusterd_txn_opinfo_obj),
+                                        gf_common_mt_txn_opinfo_obj_t);
+                if (!opinfo_obj) {
+                        ret = -1;
+                        goto out;
+                }
+
+                ret = dict_set_bin(txn_opinfo, uuid_utoa (*txn_id), opinfo_obj,
+                                   sizeof(glusterd_txn_opinfo_obj));
+                if (ret) {
+                        gf_log ("", GF_LOG_ERROR,
+                                "Unable to set opinfo for transaction ID : %s",
+                                uuid_utoa (*txn_id));
+                        goto out;
+                }
+        }
+
+        opinfo_obj->opinfo = (*opinfo);
+
+        ret = 0;
+out:
+        if (ret)
+                if (opinfo_obj)
+                        GF_FREE (opinfo_obj);
+
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
+glusterd_clear_txn_opinfo (uuid_t *txn_id)
+{
+        int32_t               ret         = -1;
+        glusterd_op_info_t    txn_op_info = {{0},};
+
+        if (!txn_id) {
+                gf_log ("", GF_LOG_ERROR, "Empty transaction id received.");
+                ret = -1;
+                goto out;
+        }
+
+        ret = glusterd_get_txn_opinfo (txn_id, &txn_op_info);
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR, "Transaction opinfo not found");
+                goto out;
+        }
+
+        dict_unref (txn_op_info.op_ctx);
+
+        dict_del(txn_opinfo, uuid_utoa (*txn_id));
+
+        ret = 0;
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
 static int glusterfs_port = GLUSTERD_DEFAULT_PORT;
 static char *glusterd_op_sm_state_names[] = {
         "Default",
@@ -147,10 +337,10 @@ glusterd_is_volume_started (glusterd_volinfo_t  *volinfo)
 }
 
 static int
-glusterd_op_sm_inject_all_acc ()
+glusterd_op_sm_inject_all_acc (uuid_t *txn_id)
 {
         int32_t                 ret = -1;
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACC, NULL);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACC, txn_id, NULL);
         gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
         return ret;
 }
@@ -445,7 +635,7 @@ glusterd_op_stage_set_volume (dict_t *dict, char **op_errstr)
          * This check is not done on the originator glusterd. The originator
          * glusterd sets this value.
          */
-        origin_glusterd = is_origin_glusterd ();
+        origin_glusterd = is_origin_glusterd (dict);
 
         if (!origin_glusterd) {
                 /* Check for v3.3.x origin glusterd */
@@ -2215,7 +2405,7 @@ glusterd_op_status_volume (dict_t *dict, char **op_errstr,
 
         GF_ASSERT (dict);
 
-        origin_glusterd = is_origin_glusterd ();
+        origin_glusterd = is_origin_glusterd (dict);
 
         ret = dict_get_uint32 (dict, "cmd", &cmd);
         if (ret)
@@ -2420,6 +2610,7 @@ glusterd_op_ac_send_lock (glusterd_op_sm_event_t *event, void *ctx)
         xlator_t             *this     = NULL;
         glusterd_peerinfo_t  *peerinfo = NULL;
         uint32_t             pending_count = 0;
+        dict_t               *dict     = NULL;
 
         this = THIS;
         priv = this->private;
@@ -2434,27 +2625,61 @@ glusterd_op_ac_send_lock (glusterd_op_sm_event_t *event, void *ctx)
                     (glusterd_op_get_op() != GD_OP_SYNC_VOLUME))
                         continue;
 
-                proc = &peerinfo->mgmt->proctable[GLUSTERD_MGMT_CLUSTER_LOCK];
-                if (proc->fn) {
-                        ret = proc->fn (NULL, this, peerinfo);
-                        if (ret) {
-                                gf_log (this->name, GF_LOG_WARNING, "Failed to "
-                                        "send lock request for operation "
-                                        "'Volume %s' to peer %s",
-                                        gd_op_list[opinfo.op],
-                                        peerinfo->hostname);
-                                continue;
+                /* Based on the op_version, acquire a cluster or volume lock */
+                if (priv->op_version < GD_OP_VERSION_4) {
+                        proc = &peerinfo->mgmt->proctable
+                                          [GLUSTERD_MGMT_CLUSTER_LOCK];
+                        if (proc->fn) {
+                                ret = proc->fn (NULL, this, peerinfo);
+                                if (ret) {
+                                        gf_log (this->name, GF_LOG_WARNING,
+                                                "Failed to send lock request "
+                                                "for operation 'Volume %s' to "
+                                                "peer %s",
+                                                gd_op_list[opinfo.op],
+                                                peerinfo->hostname);
+                                        continue;
+                                }
+                                pending_count++;
+                        }
+                } else {
+                        dict = glusterd_op_get_ctx ();
+                        dict_ref (dict);
+
+                        proc = &peerinfo->mgmt_v3->proctable
+                                          [GLUSTERD_MGMT_V3_VOLUME_LOCK];
+                        if (proc->fn) {
+                                ret = dict_set_static_ptr (dict, "peerinfo",
+                                                           peerinfo);
+                                if (ret) {
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "failed to set peerinfo");
+                                        dict_unref (dict);
+                                        goto out;
+                                }
+
+                                ret = proc->fn (NULL, this, dict);
+                                if (ret) {
+                                        gf_log (this->name, GF_LOG_WARNING,
+                                                "Failed to send volume lock "
+                                                "request for operation "
+                                                "'Volume %s' to peer %s",
+                                                gd_op_list[opinfo.op],
+                                                peerinfo->hostname);
+                                        dict_unref (dict);
+                                        continue;
+                                }
+                                pending_count++;
                         }
-                        pending_count++;
                 }
         }
 
         opinfo.pending_count = pending_count;
         if (!opinfo.pending_count)
-                ret = glusterd_op_sm_inject_all_acc ();
+                ret = glusterd_op_sm_inject_all_acc (&event->txn_id);
 
+out:
         gf_log (this->name, GF_LOG_DEBUG, "Returning with %d", ret);
-
         return ret;
 }
 
@@ -2467,17 +2692,12 @@ glusterd_op_ac_send_unlock (glusterd_op_sm_event_t *event, void *ctx)
         xlator_t             *this     = NULL;
         glusterd_peerinfo_t  *peerinfo = NULL;
         uint32_t             pending_count = 0;
+        dict_t               *dict     = NULL;
 
         this = THIS;
         priv = this->private;
         GF_ASSERT (priv);
 
-        /*ret = glusterd_unlock (MY_UUID);
-
-        if (ret)
-                goto out;
-        */
-
         list_for_each_entry (peerinfo, &priv->peers, uuid_list) {
                 GF_ASSERT (peerinfo);
 
@@ -2487,29 +2707,63 @@ glusterd_op_ac_send_unlock (glusterd_op_sm_event_t *event, void *ctx)
                     (glusterd_op_get_op() != GD_OP_SYNC_VOLUME))
                         continue;
 
-                proc = &peerinfo->mgmt->proctable[GLUSTERD_MGMT_CLUSTER_UNLOCK];
-                if (proc->fn) {
-                        ret = proc->fn (NULL, this, peerinfo);
-                        if (ret) {
-                                gf_log (this->name, GF_LOG_WARNING, "Failed to "
-                                        "send unlock request for operation "
-                                        "'Volume %s' to peer %s",
-                                        gd_op_list[opinfo.op],
-                                        peerinfo->hostname);
-                                continue;
+                /* Based on the op_version,
+                 * release the cluster or volume lock */
+                if (priv->op_version < GD_OP_VERSION_4) {
+                        proc = &peerinfo->mgmt->proctable
+                                          [GLUSTERD_MGMT_CLUSTER_UNLOCK];
+                        if (proc->fn) {
+                                ret = proc->fn (NULL, this, peerinfo);
+                                if (ret) {
+                                        gf_log (this->name, GF_LOG_WARNING,
+                                                "Failed to send unlock request "
+                                                "for operation 'Volume %s' to "
+                                                "peer %s",
+                                                gd_op_list[opinfo.op],
+                                                peerinfo->hostname);
+                                        continue;
+                                }
+                                pending_count++;
+                        }
+                } else {
+                        dict = glusterd_op_get_ctx ();
+                        dict_ref (dict);
+
+                        proc = &peerinfo->mgmt_v3->proctable
+                                          [GLUSTERD_MGMT_V3_VOLUME_UNLOCK];
+                        if (proc->fn) {
+                                ret = dict_set_static_ptr (dict, "peerinfo",
+                                                           peerinfo);
+                                if (ret) {
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "failed to set peerinfo");
+                                        dict_unref (dict);
+                                        goto out;
+                                }
+
+                                ret = proc->fn (NULL, this, dict);
+                                if (ret) {
+                                        gf_log (this->name, GF_LOG_WARNING,
+                                                "Failed to send volume unlock "
+                                                "request for operation "
+                                                "'Volume %s' to peer %s",
+                                                gd_op_list[opinfo.op],
+                                                peerinfo->hostname);
+                                        dict_unref (dict);
+                                        continue;
+                                }
+                                pending_count++;
                         }
-                        pending_count++;
                 }
         }
 
         opinfo.pending_count = pending_count;
         if (!opinfo.pending_count)
-                ret = glusterd_op_sm_inject_all_acc ();
+                ret = glusterd_op_sm_inject_all_acc (&event->txn_id);
 
+out:
         gf_log (this->name, GF_LOG_DEBUG, "Returning with %d", ret);
-
         return ret;
-
 }
 
 static int
@@ -2521,7 +2775,8 @@ glusterd_op_ac_ack_drain (glusterd_op_sm_event_t *event, void *ctx)
                 opinfo.pending_count--;
 
         if (!opinfo.pending_count)
-                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, NULL);
+                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK,
+                                                   &event->txn_id, NULL);
 
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning with %d", ret);
 
@@ -2537,43 +2792,93 @@ glusterd_op_ac_send_unlock_drain (glusterd_op_sm_event_t *event, void *ctx)
 static int
 glusterd_op_ac_lock (glusterd_op_sm_event_t *event, void *ctx)
 {
-        glusterd_op_lock_ctx_t   *lock_ctx = NULL;
-        int32_t                  ret = 0;
+        int32_t                         ret             = 0;
+        char                           *volname         = NULL;
+        glusterd_op_lock_ctx_t         *lock_ctx        = NULL;
+        glusterd_conf_t                *priv            = NULL;
+        xlator_t                       *this            = NULL;
 
         GF_ASSERT (event);
         GF_ASSERT (ctx);
 
+        this = THIS;
+        priv = this->private;
+
         lock_ctx = (glusterd_op_lock_ctx_t *)ctx;
 
-        ret = glusterd_lock (lock_ctx->uuid);
+        /* If the req came from a node running on older op_version
+         * the dict won't be present. Based on it acquiring a cluster
+         * or volume lock */
+        if (lock_ctx->dict == NULL) {
+                ret = glusterd_lock (lock_ctx->uuid);
+                glusterd_op_lock_send_resp (lock_ctx->req, ret);
+        } else {
+                ret = dict_get_str (lock_ctx->dict, "volname", &volname);
+                if (ret)
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to acquire volname");
+                else {
+                        ret = glusterd_volume_lock (volname, lock_ctx->uuid);
+                        if (ret)
+                                gf_log (this->name, GF_LOG_ERROR,
+                                        "Unable to acquire lock for %s",
+                                        volname);
+                }
 
-        gf_log (THIS->name, GF_LOG_DEBUG, "Lock Returned %d", ret);
+                glusterd_op_volume_lock_send_resp (lock_ctx->req,
+                                                   &event->txn_id, ret);
 
-        glusterd_op_lock_send_resp (lock_ctx->req, ret);
+                dict_unref (lock_ctx->dict);
+        }
 
+        gf_log (THIS->name, GF_LOG_DEBUG, "Lock Returned %d", ret);
         return ret;
 }
 
 static int
 glusterd_op_ac_unlock (glusterd_op_sm_event_t *event, void *ctx)
 {
-        int                      ret = 0;
-        glusterd_op_lock_ctx_t   *lock_ctx = NULL;
-        xlator_t                 *this = NULL;
-        glusterd_conf_t          *priv = NULL;
+        int32_t                         ret             = 0;
+        char                           *volname         = NULL;
+        glusterd_op_lock_ctx_t         *lock_ctx        = NULL;
+        glusterd_conf_t                *priv            = NULL;
+        xlator_t                       *this            = NULL;
+
 
         GF_ASSERT (event);
         GF_ASSERT (ctx);
 
         this = THIS;
         priv = this->private;
+
         lock_ctx = (glusterd_op_lock_ctx_t *)ctx;
 
-        ret = glusterd_unlock (lock_ctx->uuid);
+        /* If the req came from a node running on older op_version
+         * the dict won't be present. Based on it releasing the cluster
+         * or volume lock */
+        if (lock_ctx->dict == NULL) {
+                ret = glusterd_unlock (lock_ctx->uuid);
+                glusterd_op_unlock_send_resp (lock_ctx->req, ret);
+        } else {
+                ret = dict_get_str (lock_ctx->dict, "volname", &volname);
+                if (ret)
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to acquire volname");
+                else {
+                        ret = glusterd_volume_unlock (volname, lock_ctx->uuid);
+                        if (ret)
+                                gf_log (this->name, GF_LOG_ERROR,
+                                        "Unable to release lock for %s",
+                                        volname);
+                }
+
+                glusterd_op_volume_unlock_send_resp (lock_ctx->req,
+                                                     &event->txn_id, ret);
 
-        gf_log (this->name, GF_LOG_DEBUG, "Unlock Returned %d", ret);
+                dict_unref (lock_ctx->dict);
+        }
 
-        glusterd_op_unlock_send_resp (lock_ctx->req, ret);
+        gf_log (this->name, GF_LOG_DEBUG, "Unlock Returned %d", ret);
 
         if (priv->pending_quorum_action)
                 glusterd_do_quorum_action ();
@@ -2611,7 +2916,8 @@ glusterd_op_ac_rcvd_lock_acc (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACC, NULL);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACC,
+                                           &event->txn_id, NULL);
 
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
 
@@ -3043,7 +3349,8 @@ out:
         if (dict)
                 dict_unref (dict);
         if (ret) {
-                glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT, NULL);
+                glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT,
+                                             &event->txn_id, NULL);
                 opinfo.op_ret = ret;
         }
 
@@ -3052,7 +3359,7 @@ out:
                 opinfo.pending_count);
 
         if (!opinfo.pending_count)
-                ret = glusterd_op_sm_inject_all_acc ();
+                ret = glusterd_op_sm_inject_all_acc (&event->txn_id);
 
         gf_log (this->name, GF_LOG_DEBUG, "Returning with %d", ret);
 
@@ -3061,7 +3368,7 @@ out:
 }
 
 static int32_t
-glusterd_op_start_rb_timer (dict_t *dict)
+glusterd_op_start_rb_timer (dict_t *dict, uuid_t *txn_id)
 {
         int32_t         op = 0;
         struct timespec timeout = {0, };
@@ -3080,7 +3387,7 @@ glusterd_op_start_rb_timer (dict_t *dict)
         }
 
         if (op != GF_REPLACE_OP_START) {
-                ret = glusterd_op_sm_inject_all_acc ();
+                ret = glusterd_op_sm_inject_all_acc (txn_id);
                 goto out;
         }
 
@@ -3095,6 +3402,17 @@ glusterd_op_start_rb_timer (dict_t *dict)
                 ret = -1;
                 goto out;
         }
+
+        ret = dict_set_bin (rb_ctx, "transaction_id",
+                            txn_id, sizeof (uuid_t));
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR,
+                       "Failed to set transaction id.");
+                goto out;
+        } else
+               gf_log ("", GF_LOG_DEBUG,
+                        "transaction_id = %s", uuid_utoa (*txn_id));
+
         priv->timer = gf_timer_call_after (THIS->ctx, timeout,
                                            glusterd_do_replace_brick,
                                            (void *) rb_ctx);
@@ -3584,17 +3902,19 @@ out:
         if (dict)
                 dict_unref (dict);
         if (ret) {
-                glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT, NULL);
+                glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT,
+                                             &event->txn_id, NULL);
                 opinfo.op_ret = ret;
         }
 
         if (!opinfo.pending_count) {
                 if (op == GD_OP_REPLACE_BRICK) {
-                        ret = glusterd_op_start_rb_timer (op_dict);
+                        ret = glusterd_op_start_rb_timer (op_dict,
+                                                          &event->txn_id);
 
                 } else {
                         glusterd_op_modify_op_ctx (op, NULL);
-                        ret = glusterd_op_sm_inject_all_acc ();
+                        ret = glusterd_op_sm_inject_all_acc (&event->txn_id);
                 }
                 goto err;
         }
@@ -3619,7 +3939,8 @@ glusterd_op_ac_rcvd_stage_op_acc (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_STAGE_ACC, NULL);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_STAGE_ACC,
+                                           &event->txn_id, NULL);
 
 out:
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
@@ -3640,7 +3961,8 @@ glusterd_op_ac_stage_op_failed (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, NULL);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK,
+                                           &event->txn_id, NULL);
 
 out:
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
@@ -3661,7 +3983,8 @@ glusterd_op_ac_commit_op_failed (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, NULL);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK,
+                                           &event->txn_id, NULL);
 
 out:
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
@@ -3704,7 +4027,8 @@ glusterd_op_ac_brick_op_failed (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.brick_pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, ev_ctx->commit_ctx);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK,
+                                           &event->txn_id, ev_ctx->commit_ctx);
 
 out:
         if (ev_ctx->rsp_dict)
@@ -3746,7 +4070,7 @@ glusterd_op_ac_rcvd_commit_op_acc (glusterd_op_sm_event_t *event, void *ctx)
                         goto out;
                 }
 
-                ret = glusterd_op_start_rb_timer (op_ctx);
+                ret = glusterd_op_start_rb_timer (op_ctx, &event->txn_id);
                 if (ret) {
                         gf_log (this->name, GF_LOG_ERROR, "Couldn't start "
                                 "replace-brick operation.");
@@ -3761,10 +4085,14 @@ glusterd_op_ac_rcvd_commit_op_acc (glusterd_op_sm_event_t *event, void *ctx)
 out:
         if (commit_ack_inject) {
                 if (ret)
-                        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT, NULL);
+                        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT,
+                                                           &event->txn_id,
+                                                           NULL);
                 else if (!opinfo.pending_count) {
                         glusterd_op_modify_op_ctx (op, NULL);
-                        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_COMMIT_ACC, NULL);
+                        ret = glusterd_op_sm_inject_event
+                                                  (GD_OP_EVENT_COMMIT_ACC,
+                                                   &event->txn_id, NULL);
                 }
                 /*else do nothing*/
         }
@@ -3785,7 +4113,8 @@ glusterd_op_ac_rcvd_unlock_acc (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACC, NULL);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACC,
+                                           &event->txn_id, NULL);
 
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
 
@@ -3819,7 +4148,7 @@ glusterd_op_reset_ctx ()
 }
 
 int32_t
-glusterd_op_txn_complete ()
+glusterd_op_txn_complete (uuid_t *txn_id)
 {
         int32_t                 ret = -1;
         glusterd_conf_t         *priv = NULL;
@@ -3829,6 +4158,7 @@ glusterd_op_txn_complete ()
         rpcsvc_request_t        *req = NULL;
         void                    *ctx = NULL;
         char                    *op_errstr = NULL;
+        char                    *volname = NULL;
         xlator_t                *this = NULL;
 
         this = THIS;
@@ -3851,14 +4181,29 @@ glusterd_op_txn_complete ()
         glusterd_op_reset_ctx ();
         glusterd_op_clear_errstr ();
 
-        ret = glusterd_unlock (MY_UUID);
-
-        /* unlock cant/shouldnt fail here!! */
-        if (ret) {
-                gf_log (this->name, GF_LOG_CRITICAL,
-                        "Unable to clear local lock, ret: %d", ret);
+        /* Based on the op-version, we release the cluster or volume lock */
+        if (priv->op_version < GD_OP_VERSION_4) {
+                ret = glusterd_unlock (MY_UUID);
+                /* unlock cant/shouldnt fail here!! */
+                if (ret)
+                        gf_log (this->name, GF_LOG_CRITICAL,
+                                "Unable to clear local lock, ret: %d", ret);
+                else
+                        gf_log (this->name, GF_LOG_DEBUG, "Cleared local lock");
         } else {
-                gf_log (this->name, GF_LOG_DEBUG, "Cleared local lock");
+                ret = dict_get_str (ctx, "volname", &volname);
+                if (ret)
+                        gf_log ("", GF_LOG_INFO,
+                                "No Volume name present. "
+                                "Locks have not been held.");
+
+                if (volname) {
+                        ret = glusterd_volume_unlock (volname, MY_UUID);
+                        if (ret)
+                                gf_log (this->name, GF_LOG_ERROR,
+                                        "Unable to release lock for %s",
+                                        volname);
+                }
         }
 
         ret = glusterd_op_send_cli_response (op, op_ret,
@@ -3877,6 +4222,13 @@ glusterd_op_txn_complete ()
 
         if (priv->pending_quorum_action)
                 glusterd_do_quorum_action ();
+
+        /* Clearing the transaction opinfo */
+        ret = glusterd_clear_txn_opinfo (txn_id);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to clear transaction's opinfo");
+
         gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
         return ret;
 }
@@ -3888,7 +4240,7 @@ glusterd_op_ac_unlocked_all (glusterd_op_sm_event_t *event, void *ctx)
 
         GF_ASSERT (event);
 
-        ret = glusterd_op_txn_complete ();
+        ret = glusterd_op_txn_complete (&event->txn_id);
 
         gf_log (THIS->name, GF_LOG_DEBUG, "Returning %d", ret);
 
@@ -3905,6 +4257,7 @@ glusterd_op_ac_stage_op (glusterd_op_sm_event_t *event, void *ctx)
         char                    *op_errstr = NULL;
         dict_t                  *dict = NULL;
         xlator_t                *this = NULL;
+        uuid_t                  *txn_id = NULL;
 
         this = THIS;
         GF_ASSERT (this);
@@ -3930,9 +4283,27 @@ glusterd_op_ac_stage_op (glusterd_op_sm_event_t *event, void *ctx)
                         status);
         }
 
+        txn_id = GF_CALLOC (1, sizeof(uuid_t), gf_common_mt_uuid_t);
+
+        if (txn_id)
+                uuid_copy (*txn_id, event->txn_id);
+        else {
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_set_bin (rsp_dict, "transaction_id",
+                            txn_id, sizeof(uuid_t *));
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                       "Failed to set transaction id.");
+                goto out;
+        }
+
         ret = glusterd_op_stage_send_resp (req_ctx->req, req_ctx->op,
                                            status, op_errstr, rsp_dict);
 
+out:
         if (op_errstr && (strcmp (op_errstr, "")))
                 GF_FREE (op_errstr);
 
@@ -3994,6 +4365,7 @@ glusterd_op_ac_commit_op (glusterd_op_sm_event_t *event, void *ctx)
         dict_t                   *dict       = NULL;
         dict_t                   *rsp_dict   = NULL;
         xlator_t                 *this       = NULL;
+        uuid_t                   *txn_id     = NULL;
 
         this = THIS;
         GF_ASSERT (this);
@@ -4023,10 +4395,27 @@ glusterd_op_ac_commit_op (glusterd_op_sm_event_t *event, void *ctx)
                         "'Volume %s' failed: %d", gd_op_list[req_ctx->op],
                         status);
 
+        txn_id = GF_CALLOC (1, sizeof(uuid_t), gf_common_mt_uuid_t);
+
+        if (txn_id)
+                uuid_copy (*txn_id, event->txn_id);
+        else {
+                ret = -1;
+                goto out;
+        }
+
+        ret = dict_set_bin (rsp_dict, "transaction_id",
+                            txn_id, sizeof(uuid_t));
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                       "Failed to set transaction id.");
+                goto out;
+        }
+
         ret = glusterd_op_commit_send_resp (req_ctx->req, req_ctx->op,
                                             status, op_errstr, rsp_dict);
 
-        glusterd_op_fini_ctx ();
+out:
         if (op_errstr && (strcmp (op_errstr, "")))
                 GF_FREE (op_errstr);
 
@@ -4055,7 +4444,6 @@ glusterd_op_ac_send_commit_failed (glusterd_op_sm_event_t *event, void *ctx)
                                             opinfo.op_ret, opinfo.op_errstr,
                                             op_ctx);
 
-        glusterd_op_fini_ctx ();
         if (opinfo.op_errstr && (strcmp (opinfo.op_errstr, ""))) {
                 GF_FREE (opinfo.op_errstr);
                 opinfo.op_errstr = NULL;
@@ -5237,7 +5625,8 @@ glusterd_op_ac_send_brick_op (glusterd_op_sm_event_t *event, void *ctx)
 
         if (!opinfo.pending_count && !opinfo.brick_pending_count) {
                 glusterd_clear_pending_nodes (&opinfo.pending_bricks);
-                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, req_ctx);
+                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK,
+                                                   &event->txn_id, req_ctx);
         }
 
 out:
@@ -5291,7 +5680,8 @@ glusterd_op_ac_rcvd_brick_op_acc (glusterd_op_sm_event_t *event, void *ctx)
         if (opinfo.brick_pending_count > 0)
                 goto out;
 
-        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, ev_ctx->commit_ctx);
+        ret = glusterd_op_sm_inject_event (GD_OP_EVENT_ALL_ACK, &event->txn_id,
+                                           ev_ctx->commit_ctx);
 
 out:
         if (ev_ctx->rsp_dict)
@@ -5665,7 +6055,7 @@ glusterd_op_sm_new_event (glusterd_op_sm_event_type_t event_type,
 
 int
 glusterd_op_sm_inject_event (glusterd_op_sm_event_type_t event_type,
-                             void *ctx)
+                             uuid_t *txn_id, void *ctx)
 {
         int32_t                 ret = -1;
         glusterd_op_sm_event_t  *event = NULL;
@@ -5680,6 +6070,9 @@ glusterd_op_sm_inject_event (glusterd_op_sm_event_type_t event_type,
 
         event->ctx = ctx;
 
+        if (txn_id)
+                uuid_copy (event->txn_id, *txn_id);
+
         gf_log (THIS->name, GF_LOG_DEBUG, "Enqueue event: '%s'",
                 glusterd_op_sm_event_name_get (event->event));
         list_add_tail (&event->list, &gd_op_sm_queue);
@@ -5740,6 +6133,7 @@ glusterd_op_sm ()
         glusterd_op_sm_t                *state = NULL;
         glusterd_op_sm_event_type_t     event_type = GD_OP_EVENT_NONE;
         xlator_t                        *this = NULL;
+        glusterd_op_info_t              txn_op_info;
 
         this = THIS;
         GF_ASSERT (this);
@@ -5760,6 +6154,20 @@ glusterd_op_sm ()
                                 "type: '%s'",
                                 glusterd_op_sm_event_name_get(event_type));
 
+                        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s",
+                                uuid_utoa (event->txn_id));
+
+                        ret = glusterd_get_txn_opinfo (&event->txn_id,
+                                                       &txn_op_info);
+                        if (ret) {
+                                gf_log (this->name, GF_LOG_ERROR,
+                                        "Unable to get transaction's opinfo");
+                                glusterd_destroy_op_event_ctx (event);
+                                GF_FREE (event);
+                                continue;
+                        } else
+                                opinfo = txn_op_info;
+
                         state = glusterd_op_state_table[opinfo.state.state];
 
                         GF_ASSERT (state);
@@ -5790,8 +6198,27 @@ glusterd_op_sm ()
                                 return ret;
                         }
 
+                        if ((state[event_type].next_state ==
+                             GD_OP_STATE_DEFAULT) &&
+                           (event_type == GD_OP_EVENT_UNLOCK)) {
+                                /* Clearing the transaction opinfo */
+                                ret = glusterd_clear_txn_opinfo(&event->txn_id);
+                                if (ret)
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "Unable to clear "
+                                                "transaction's opinfo");
+                        } else {
+                                ret = glusterd_set_txn_opinfo (&event->txn_id,
+                                                               &opinfo);
+                                if (ret)
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "Unable to set "
+                                                "transaction's opinfo");
+                        }
+
                         glusterd_destroy_op_event_ctx (event);
                         GF_FREE (event);
+
                 }
         }
 
@@ -5845,52 +6272,6 @@ glusterd_op_clear_op (glusterd_op_t op)
 }
 
 int32_t
-glusterd_op_init_ctx (glusterd_op_t op)
-{
-        int     ret = 0;
-        dict_t *dict = NULL;
-        xlator_t *this = NULL;
-
-        this = THIS;
-        GF_ASSERT (this);
-        GF_ASSERT (GD_OP_NONE < op && op < GD_OP_MAX);
-
-        if (_gf_false == glusterd_need_brick_op (op)) {
-                gf_log (this->name, GF_LOG_DEBUG, "Received op: %s, returning",
-                        gd_op_list[op]);
-                goto out;
-        }
-        dict = dict_new ();
-        if (dict == NULL) {
-                ret = -1;
-                goto out;
-        }
-        ret = glusterd_op_set_ctx (dict);
-        if (ret)
-                goto out;
-out:
-        gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
-        return ret;
-}
-
-
-
-int32_t
-glusterd_op_fini_ctx ()
-{
-        dict_t *dict = NULL;
-
-        dict = glusterd_op_get_ctx ();
-        if (dict)
-                dict_unref (dict);
-
-        glusterd_op_reset_ctx ();
-        return 0;
-}
-
-
-
-int32_t
 glusterd_op_free_ctx (glusterd_op_t op, void *ctx)
 {
 
diff --git a/xlators/mgmt/glusterd/src/glusterd-op-sm.h b/xlators/mgmt/glusterd/src/glusterd-op-sm.h
index 1125368cef9..53d4e2ff4b1 100644
--- a/xlators/mgmt/glusterd/src/glusterd-op-sm.h
+++ b/xlators/mgmt/glusterd/src/glusterd-op-sm.h
@@ -77,6 +77,7 @@ struct glusterd_op_sm_event_ {
         struct list_head                list;
         void                            *ctx;
         glusterd_op_sm_event_type_t     event;
+        uuid_t                          txn_id;
 };
 
 typedef struct glusterd_op_sm_event_ glusterd_op_sm_event_t;
@@ -119,6 +120,7 @@ typedef struct glusterd_op_log_filename_ctx_ glusterd_op_log_filename_ctx_t;
 
 struct glusterd_op_lock_ctx_ {
         uuid_t                  uuid;
+        dict_t                 *dict;
         rpcsvc_request_t        *req;
 };
 
@@ -180,7 +182,7 @@ glusterd_op_sm_new_event (glusterd_op_sm_event_type_t event_type,
                           glusterd_op_sm_event_t **new_event);
 int
 glusterd_op_sm_inject_event (glusterd_op_sm_event_type_t event_type,
-                             void *ctx);
+                             uuid_t *txn_id, void *ctx);
 
 int
 glusterd_op_sm_init ();
@@ -264,10 +266,7 @@ glusterd_op_init_commit_rsp_dict (glusterd_op_t op);
 
 void
 glusterd_op_modify_op_ctx (glusterd_op_t op, void *op_ctx);
-int32_t
-glusterd_op_init_ctx (glusterd_op_t op);
-int32_t
-glusterd_op_fini_ctx ();
+
 int32_t
 glusterd_volume_stats_read_perf (char *brick_path, int32_t blk_size,
                 int32_t blk_count, double *throughput, double *time);
@@ -296,4 +295,16 @@ int
 glusterd_is_valid_vg (glusterd_brickinfo_t *brick, int check_tag, char *msg);
 #endif
 
+int32_t
+glusterd_get_txn_opinfo (uuid_t *txn_id, glusterd_op_info_t  *opinfo);
+
+int32_t
+glusterd_set_txn_opinfo (uuid_t *txn_id, glusterd_op_info_t  *opinfo);
+
+int32_t
+glusterd_clear_txn_opinfo (uuid_t *txn_id);
+
+int32_t
+glusterd_generate_txn_id (dict_t *dict, uuid_t **txn_id);
+
 #endif
diff --git a/xlators/mgmt/glusterd/src/glusterd-quota.c b/xlators/mgmt/glusterd/src/glusterd-quota.c
index d13533aa6c1..cf23b640478 100644
--- a/xlators/mgmt/glusterd/src/glusterd-quota.c
+++ b/xlators/mgmt/glusterd/src/glusterd-quota.c
@@ -824,7 +824,7 @@ glusterd_quota_limit_usage (glusterd_volinfo_t *volinfo, dict_t *dict,
                 }
         }
 
-        if (is_origin_glusterd ()) {
+        if (is_origin_glusterd (dict)) {
                 ret = glusterd_set_quota_limit (volinfo->volname, path,
                                                 hard_limit, soft_limit,
                                                 op_errstr);
@@ -919,7 +919,7 @@ glusterd_quota_remove_limits (glusterd_volinfo_t *volinfo, dict_t *dict,
         if (ret)
                 goto out;
 
-        if (is_origin_glusterd ()) {
+        if (is_origin_glusterd (dict)) {
                 ret = glusterd_remove_quota_limit (volinfo->volname, path,
                                                    op_errstr);
                 if (ret)
@@ -1385,7 +1385,7 @@ glusterd_op_stage_quota (dict_t *dict, char **op_errstr, dict_t *rsp_dict)
         case GF_QUOTA_OPTION_TYPE_ENABLE:
         case GF_QUOTA_OPTION_TYPE_LIST:
                 /* Fuse mount req. only for enable & list-usage options*/
-                if (is_origin_glusterd () &&
+                if (is_origin_glusterd (dict) &&
                     !glusterd_is_fuse_available ()) {
                         *op_errstr = gf_strdup ("Fuse unavailable");
                         ret = -1;
diff --git a/xlators/mgmt/glusterd/src/glusterd-rebalance.c b/xlators/mgmt/glusterd/src/glusterd-rebalance.c
index b2805613517..b274e3367da 100644
--- a/xlators/mgmt/glusterd/src/glusterd-rebalance.c
+++ b/xlators/mgmt/glusterd/src/glusterd-rebalance.c
@@ -545,7 +545,7 @@ glusterd_op_stage_rebalance (dict_t *dict, char **op_errstr)
         case GF_DEFRAG_CMD_START:
         case GF_DEFRAG_CMD_START_LAYOUT_FIX:
         case GF_DEFRAG_CMD_START_FORCE:
-                if (is_origin_glusterd ()) {
+                if (is_origin_glusterd (dict)) {
                         op_ctx = glusterd_op_get_ctx ();
                         if (!op_ctx) {
                                 ret = -1;
diff --git a/xlators/mgmt/glusterd/src/glusterd-replace-brick.c b/xlators/mgmt/glusterd/src/glusterd-replace-brick.c
index 5c3fc2d8259..f26108f89c2 100644
--- a/xlators/mgmt/glusterd/src/glusterd-replace-brick.c
+++ b/xlators/mgmt/glusterd/src/glusterd-replace-brick.c
@@ -31,6 +31,7 @@
                   DEFAULT_VAR_RUN_DIRECTORY"/%s-"RB_CLIENT_MOUNTPOINT,      \
                   volinfo->volname);
 
+extern uuid_t global_txn_id;
 
 int
 glusterd_get_replace_op_str (gf1_cli_replace_op op, char *op_str)
@@ -325,7 +326,7 @@ glusterd_op_stage_replace_brick (dict_t *dict, char **op_errstr,
                         ret = -1;
                         goto out;
                 }
-                if (is_origin_glusterd ()) {
+                if (is_origin_glusterd (dict)) {
                         if (!ctx) {
                                 ret = -1;
                                 gf_log (this->name, GF_LOG_ERROR,
@@ -1631,7 +1632,7 @@ glusterd_op_replace_brick (dict_t *dict, dict_t *rsp_dict)
                 /* Set task-id, if available, in op_ctx dict for operations
                  * other than start
                  */
-                if  (is_origin_glusterd ()) {
+                if  (is_origin_glusterd (dict)) {
                         ctx = glusterd_op_get_ctx();
                         if (!ctx) {
                                 gf_log (this->name, GF_LOG_ERROR, "Failed to "
@@ -1894,6 +1895,7 @@ glusterd_do_replace_brick (void *data)
         glusterd_brickinfo_t   *src_brickinfo = NULL;
         glusterd_brickinfo_t   *dst_brickinfo = NULL;
 	glusterd_conf_t	       *priv = NULL;
+        uuid_t                 *txn_id = &global_txn_id;
 
         int ret = 0;
 
@@ -1913,6 +1915,10 @@ glusterd_do_replace_brick (void *data)
         gf_log ("", GF_LOG_DEBUG,
                 "Replace brick operation detected");
 
+        ret = dict_get_bin (dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
+
         ret = dict_get_int32 (dict, "operation", &op);
         if (ret) {
                 gf_log ("", GF_LOG_DEBUG,
@@ -2008,9 +2014,11 @@ glusterd_do_replace_brick (void *data)
 
 out:
         if (ret)
-                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT, NULL);
+                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT,
+                                                   txn_id, NULL);
         else
-                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_COMMIT_ACC, NULL);
+                ret = glusterd_op_sm_inject_event (GD_OP_EVENT_COMMIT_ACC,
+                                                   txn_id, NULL);
 
         synclock_lock (&priv->big_lock);
         {
diff --git a/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c b/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c
index cd81383e921..9af26cfab07 100644
--- a/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c
+++ b/xlators/mgmt/glusterd/src/glusterd-rpc-ops.c
@@ -33,6 +33,7 @@
 
 
 extern glusterd_op_info_t opinfo;
+extern uuid_t global_txn_id;
 
 int32_t
 glusterd_op_send_cli_response (glusterd_op_t op, int32_t op_ret,
@@ -574,6 +575,7 @@ __glusterd_cluster_lock_cbk (struct rpc_req *req, struct iovec *iov,
         glusterd_op_sm_event_type_t   event_type = GD_OP_EVENT_NONE;
         glusterd_peerinfo_t           *peerinfo = NULL;
         xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = &global_txn_id;
 
         this = THIS;
         GF_ASSERT (this);
@@ -618,7 +620,7 @@ out:
                 event_type = GD_OP_EVENT_RCVD_ACC;
         }
 
-        ret = glusterd_op_sm_inject_event (event_type, NULL);
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, NULL);
 
         if (!ret) {
                 glusterd_friend_sm ();
@@ -637,6 +639,168 @@ glusterd_cluster_lock_cbk (struct rpc_req *req, struct iovec *iov,
                                         __glusterd_cluster_lock_cbk);
 }
 
+static int32_t
+glusterd_vol_lock_cbk_fn (struct rpc_req *req, struct iovec *iov,
+                            int count, void *myframe)
+{
+        gd1_mgmt_volume_lock_rsp      rsp   = {{0},};
+        int                           ret   = -1;
+        int32_t                       op_ret = -1;
+        glusterd_op_sm_event_type_t   event_type = GD_OP_EVENT_NONE;
+        glusterd_peerinfo_t           *peerinfo = NULL;
+        xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = NULL;
+
+        this = THIS;
+        GF_ASSERT (this);
+        GF_ASSERT (req);
+
+        if (-1 == req->rpc_status) {
+                rsp.op_ret   = -1;
+                rsp.op_errno = EINVAL;
+                goto out;
+        }
+
+        ret = xdr_to_generic (*iov, &rsp,
+                              (xdrproc_t)xdr_gd1_mgmt_volume_lock_rsp);
+        if (ret < 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to decode volume lock "
+                        "response received from peer");
+                rsp.op_ret   = -1;
+                rsp.op_errno = EINVAL;
+                goto out;
+        }
+
+        op_ret = rsp.op_ret;
+
+        txn_id = &rsp.txn_id;
+
+        gf_log (this->name, (op_ret) ? GF_LOG_ERROR : GF_LOG_DEBUG,
+                "Received volume lock %s from uuid: %s",
+                (op_ret) ? "RJT" : "ACC", uuid_utoa (rsp.uuid));
+
+        ret = glusterd_friend_find (rsp.uuid, NULL, &peerinfo);
+        if (ret) {
+                gf_log (this->name, GF_LOG_CRITICAL,
+                        "Volume lock response received "
+                        "from unknown peer: %s. Ignoring response",
+                         uuid_utoa (rsp.uuid));
+                goto out;
+        }
+
+        if (op_ret) {
+                event_type = GD_OP_EVENT_RCVD_RJT;
+                opinfo.op_ret = op_ret;
+                opinfo.op_errstr = gf_strdup ("Another transaction could be in "
+                                              "progress. Please try again after"
+                                              " sometime.");
+        } else {
+                event_type = GD_OP_EVENT_RCVD_ACC;
+        }
+
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, NULL);
+
+        if (!ret) {
+                glusterd_friend_sm ();
+                glusterd_op_sm ();
+        }
+
+out:
+        GLUSTERD_STACK_DESTROY (((call_frame_t *)myframe));
+        return ret;
+}
+
+int32_t
+glusterd_vol_lock_cbk (struct rpc_req *req, struct iovec *iov,
+                       int count, void *myframe)
+{
+        return glusterd_big_locked_cbk (req, iov, count, myframe,
+                                        glusterd_vol_lock_cbk_fn);
+}
+
+static int32_t
+glusterd_vol_unlock_cbk_fn (struct rpc_req *req, struct iovec *iov,
+                           int count, void *myframe)
+{
+        gd1_mgmt_volume_unlock_rsp    rsp   = {{0},};
+        int                           ret   = -1;
+        int32_t                       op_ret = -1;
+        glusterd_op_sm_event_type_t   event_type = GD_OP_EVENT_NONE;
+        glusterd_peerinfo_t           *peerinfo = NULL;
+        xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = NULL;
+
+        this = THIS;
+        GF_ASSERT (this);
+        GF_ASSERT (req);
+
+        if (-1 == req->rpc_status) {
+                rsp.op_ret   = -1;
+                rsp.op_errno = EINVAL;
+                goto out;
+        }
+
+        ret = xdr_to_generic (*iov, &rsp,
+                              (xdrproc_t)xdr_gd1_mgmt_volume_unlock_rsp);
+        if (ret < 0) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to decode volume unlock "
+                        "response received from peer");
+                rsp.op_ret   = -1;
+                rsp.op_errno = EINVAL;
+                goto out;
+        }
+
+        op_ret = rsp.op_ret;
+
+        txn_id = &rsp.txn_id;
+
+        gf_log (this->name, (op_ret) ? GF_LOG_ERROR : GF_LOG_DEBUG,
+                "Received volume unlock %s from uuid: %s",
+                (op_ret) ? "RJT" : "ACC",
+                uuid_utoa (rsp.uuid));
+
+        ret = glusterd_friend_find (rsp.uuid, NULL, &peerinfo);
+
+        if (ret) {
+                gf_log (this->name, GF_LOG_CRITICAL,
+                        "Volume unlock response received "
+                        "from unknown peer: %s. Ignoring response",
+                        uuid_utoa (rsp.uuid));
+                goto out;
+        }
+
+        if (op_ret) {
+                event_type = GD_OP_EVENT_RCVD_RJT;
+                opinfo.op_ret = op_ret;
+                opinfo.op_errstr = gf_strdup ("Another transaction could be in "
+                                              "progress. Please try again after"
+                                              " sometime.");
+        } else {
+                event_type = GD_OP_EVENT_RCVD_ACC;
+        }
+
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, NULL);
+
+        if (!ret) {
+                glusterd_friend_sm ();
+                glusterd_op_sm ();
+        }
+
+out:
+        GLUSTERD_STACK_DESTROY (((call_frame_t *)myframe));
+        return ret;
+}
+
+int32_t
+glusterd_vol_unlock_cbk (struct rpc_req *req, struct iovec *iov,
+                         int count, void *myframe)
+{
+        return glusterd_big_locked_cbk (req, iov, count, myframe,
+                                        glusterd_vol_unlock_cbk_fn);
+}
+
 int32_t
 __glusterd_cluster_unlock_cbk (struct rpc_req *req, struct iovec *iov,
                                  int count, void *myframe)
@@ -647,6 +811,7 @@ __glusterd_cluster_unlock_cbk (struct rpc_req *req, struct iovec *iov,
         glusterd_op_sm_event_type_t   event_type = GD_OP_EVENT_NONE;
         glusterd_peerinfo_t           *peerinfo = NULL;
         xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = &global_txn_id;
 
         this = THIS;
         GF_ASSERT (this);
@@ -688,7 +853,7 @@ out:
                 event_type = GD_OP_EVENT_RCVD_ACC;
         }
 
-        ret = glusterd_op_sm_inject_event (event_type, NULL);
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, NULL);
 
         if (!ret) {
                 glusterd_friend_sm ();
@@ -720,6 +885,7 @@ __glusterd_stage_op_cbk (struct rpc_req *req, struct iovec *iov,
         char                          err_str[2048] = {0};
         char                          *peer_str = NULL;
         xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = NULL;
 
         this = THIS;
         GF_ASSERT (this);
@@ -772,11 +938,17 @@ out:
                 "Received stage %s from uuid: %s",
                 (op_ret) ? "RJT" : "ACC", uuid_utoa (rsp.uuid));
 
+        ret = dict_get_bin (dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
+
         ret = glusterd_friend_find (rsp.uuid, NULL, &peerinfo);
 
         if (ret) {
                 gf_log (this->name, GF_LOG_CRITICAL, "Stage response received "
-                        "from unknown peer: %s", uuid_utoa (rsp.uuid));
+                        "from unknown peer: %s. Ignoring response.",
+                        uuid_utoa (rsp.uuid));
+                goto out;
         }
 
         if (op_ret) {
@@ -807,7 +979,7 @@ out:
                 break;
         }
 
-        ret = glusterd_op_sm_inject_event (event_type, NULL);
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, NULL);
 
         if (!ret) {
                 glusterd_friend_sm ();
@@ -847,6 +1019,8 @@ __glusterd_commit_op_cbk (struct rpc_req *req, struct iovec *iov,
         char                          err_str[2048] = {0};
         char                          *peer_str = NULL;
         xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = NULL;
+
 
         this = THIS;
         GF_ASSERT (this);
@@ -900,6 +1074,10 @@ __glusterd_commit_op_cbk (struct rpc_req *req, struct iovec *iov,
                 "Received commit %s from uuid: %s",
                 (op_ret)?"RJT":"ACC", uuid_utoa (rsp.uuid));
 
+        ret = dict_get_bin (dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
+
         ret = glusterd_friend_find (rsp.uuid, NULL, &peerinfo);
 
         if (ret) {
@@ -979,7 +1157,7 @@ __glusterd_commit_op_cbk (struct rpc_req *req, struct iovec *iov,
         }
 
 out:
-        ret = glusterd_op_sm_inject_event (event_type, NULL);
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, NULL);
 
         if (!ret) {
                 glusterd_friend_sm ();
@@ -1216,6 +1394,107 @@ out:
 }
 
 int32_t
+glusterd_vol_lock (call_frame_t *frame, xlator_t *this,
+                   void *data)
+{
+        gd1_mgmt_volume_lock_req         req         = {{0},};
+        int                              ret         = -1;
+        glusterd_peerinfo_t             *peerinfo    = NULL;
+        glusterd_conf_t                 *priv        = NULL;
+        call_frame_t                    *dummy_frame = NULL;
+        dict_t                          *dict        = NULL;
+
+        if (!this)
+                goto out;
+
+        dict = data;
+
+        priv = this->private;
+        GF_ASSERT (priv);
+
+        ret = dict_get_ptr (dict, "peerinfo", VOID (&peerinfo));
+        if (ret)
+                goto out;
+
+        //peerinfo should not be in payload
+        dict_del (dict, "peerinfo");
+
+        glusterd_get_uuid (&req.uuid);
+
+        ret = dict_allocate_and_serialize (dict, &req.dict.dict_val,
+                                           &req.dict.dict_len);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR, "Failed to serialize dict "
+                        "to request buffer");
+                goto out;
+        }
+
+        dummy_frame = create_frame (this, this->ctx->pool);
+        if (!dummy_frame)
+                goto out;
+
+        ret = glusterd_submit_request (peerinfo->rpc, &req, dummy_frame,
+                                       peerinfo->mgmt_v3,
+                                       GLUSTERD_MGMT_V3_VOLUME_LOCK, NULL,
+                                       this, glusterd_vol_lock_cbk,
+                                       (xdrproc_t)xdr_gd1_mgmt_volume_lock_req);
+out:
+        gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
+glusterd_vol_unlock (call_frame_t *frame, xlator_t *this,
+                   void *data)
+{
+        gd1_mgmt_volume_unlock_req       req         = {{0},};
+        int                              ret         = -1;
+        glusterd_peerinfo_t             *peerinfo    = NULL;
+        glusterd_conf_t                 *priv        = NULL;
+        call_frame_t                    *dummy_frame = NULL;
+        dict_t                          *dict        = NULL;
+
+        if (!this)
+                goto out;
+
+        dict = data;
+
+        priv = this->private;
+        GF_ASSERT (priv);
+
+        ret = dict_get_ptr (dict, "peerinfo", VOID (&peerinfo));
+        if (ret)
+                goto out;
+
+        //peerinfo should not be in payload
+        dict_del (dict, "peerinfo");
+
+        glusterd_get_uuid (&req.uuid);
+
+        ret = dict_allocate_and_serialize (dict, &req.dict.dict_val,
+                                           &req.dict.dict_len);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR, "Failed to serialize dict "
+                        "to request buffer");
+                goto out;
+        }
+
+        dummy_frame = create_frame (this, this->ctx->pool);
+        if (!dummy_frame)
+                goto out;
+
+        ret = glusterd_submit_request (peerinfo->rpc, &req, dummy_frame,
+                                       peerinfo->mgmt_v3,
+                                       GLUSTERD_MGMT_V3_VOLUME_UNLOCK, NULL,
+                                       this, glusterd_vol_unlock_cbk,
+                                       (xdrproc_t)
+                                       xdr_gd1_mgmt_volume_unlock_req);
+out:
+        gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
 glusterd_cluster_unlock (call_frame_t *frame, xlator_t *this,
                             void *data)
 {
@@ -1378,6 +1657,7 @@ __glusterd_brick_op_cbk (struct rpc_req *req, struct iovec *iov,
         glusterd_req_ctx_t            *req_ctx = NULL;
         glusterd_pending_node_t       *node = NULL;
         xlator_t                      *this = NULL;
+        uuid_t                        *txn_id = &global_txn_id;
 
         this = THIS;
         GF_ASSERT (this);
@@ -1440,6 +1720,11 @@ __glusterd_brick_op_cbk (struct rpc_req *req, struct iovec *iov,
                 }
         }
 out:
+
+        ret = dict_get_bin (req_ctx->dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
+
         ev_ctx = GF_CALLOC (1, sizeof (*ev_ctx), gf_gld_mt_brick_rsp_ctx_t);
         GF_ASSERT (ev_ctx);
         if (op_ret) {
@@ -1452,7 +1737,7 @@ out:
         ev_ctx->pending_node = frame->cookie;
         ev_ctx->rsp_dict  = dict;
         ev_ctx->commit_ctx = frame->local;
-        ret = glusterd_op_sm_inject_event (event_type, ev_ctx);
+        ret = glusterd_op_sm_inject_event (event_type, txn_id, ev_ctx);
         if (!ret) {
                 glusterd_friend_sm ();
                 glusterd_op_sm ();
@@ -1477,6 +1762,7 @@ int32_t
 glusterd_brick_op (call_frame_t *frame, xlator_t *this,
                       void *data)
 {
+
         gd1_mgmt_brick_op_req           *req = NULL;
         int                             ret = 0;
         glusterd_conf_t                 *priv = NULL;
@@ -1487,6 +1773,7 @@ glusterd_brick_op (call_frame_t *frame, xlator_t *this,
         glusterd_req_ctx_t              *req_ctx = NULL;
         struct rpc_clnt                 *rpc = NULL;
         dict_t                          *op_ctx = NULL;
+        uuid_t                          *txn_id = &global_txn_id;
 
         if (!this) {
                 ret = -1;
@@ -1509,6 +1796,11 @@ glusterd_brick_op (call_frame_t *frame, xlator_t *this,
                 goto out;
         }
 
+
+        ret = dict_get_bin (req_ctx->dict, "transaction_id", (void **)&txn_id);
+
+        gf_log ("", GF_LOG_DEBUG, "transaction ID = %s", uuid_utoa (*txn_id));
+
         list_for_each_entry (pending_node, &opinfo.pending_bricks, list) {
                 dummy_frame = create_frame (this, this->ctx->pool);
                 if (!dummy_frame)
@@ -1587,7 +1879,8 @@ glusterd_brick_op (call_frame_t *frame, xlator_t *this,
 
 out:
         if (ret) {
-                glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT, data);
+                glusterd_op_sm_inject_event (GD_OP_EVENT_RCVD_RJT,
+                                             txn_id, data);
                 opinfo.op_ret = ret;
         }
         gf_log (this->name, GF_LOG_DEBUG, "Returning %d", ret);
@@ -1615,6 +1908,12 @@ struct rpc_clnt_procedure gd_mgmt_actors[GLUSTERD_MGMT_MAXVALUE] = {
         [GLUSTERD_MGMT_COMMIT_OP]      = {"COMMIT_OP", glusterd_commit_op},
 };
 
+struct rpc_clnt_procedure gd_mgmt_v3_actors[GLUSTERD_MGMT_V3_MAXVALUE] = {
+        [GLUSTERD_MGMT_V3_NULL]           = {"NULL", NULL },
+        [GLUSTERD_MGMT_V3_VOLUME_LOCK]    = {"VOLUME_LOCK", glusterd_vol_lock},
+        [GLUSTERD_MGMT_V3_VOLUME_UNLOCK]  = {"VOLUME_UNLOCK", glusterd_vol_unlock},
+};
+
 struct rpc_clnt_program gd_mgmt_prog = {
         .progname  = "glusterd mgmt",
         .prognum   = GD_MGMT_PROGRAM,
@@ -1639,4 +1938,10 @@ struct rpc_clnt_program gd_peer_prog = {
         .numproc   = GLUSTERD_FRIEND_MAXVALUE,
 };
 
-
+struct rpc_clnt_program gd_mgmt_v3_prog = {
+        .progname  = "glusterd mgmt v3",
+        .prognum   = GD_MGMT_PROGRAM,
+        .progver   = GD_MGMT_V3_VERSION,
+        .proctable = gd_mgmt_v3_actors,
+        .numproc   = GLUSTERD_MGMT_V3_MAXVALUE,
+};
diff --git a/xlators/mgmt/glusterd/src/glusterd-sm.h b/xlators/mgmt/glusterd/src/glusterd-sm.h
index e29bb7277e3..b9bedbe6994 100644
--- a/xlators/mgmt/glusterd/src/glusterd-sm.h
+++ b/xlators/mgmt/glusterd/src/glusterd-sm.h
@@ -97,6 +97,7 @@ struct glusterd_peerinfo_ {
         struct rpc_clnt                 *rpc;
         rpc_clnt_prog_t                 *mgmt;
         rpc_clnt_prog_t                 *peer;
+        rpc_clnt_prog_t                 *mgmt_v3;
         int                             connected;
         gf_store_handle_t         *shandle;
         glusterd_sm_tr_log_t            sm_log;
diff --git a/xlators/mgmt/glusterd/src/glusterd-syncop.c b/xlators/mgmt/glusterd/src/glusterd-syncop.c
index c9a1b5a7561..5eb5e9f3899 100644
--- a/xlators/mgmt/glusterd/src/glusterd-syncop.c
+++ b/xlators/mgmt/glusterd/src/glusterd-syncop.c
@@ -17,6 +17,9 @@
 #include "glusterd.h"
 #include "glusterd-op-sm.h"
 #include "glusterd-utils.h"
+#include "glusterd-locks.h"
+
+extern glusterd_op_info_t opinfo;
 
 static inline void
 gd_synctask_barrier_wait (struct syncargs *args, int count)
@@ -31,6 +34,62 @@ gd_synctask_barrier_wait (struct syncargs *args, int count)
 }
 
 static void
+gd_mgmt_v3_collate_errors (struct syncargs *args, int op_ret, int op_errno,
+                           char *op_errstr, int op_code,
+                           glusterd_peerinfo_t *peerinfo, u_char *uuid)
+{
+        char     err_str[PATH_MAX] = "Please check log file for details.";
+        char     op_err[PATH_MAX] = "";
+        char    *peer_str      = NULL;
+
+        if (op_ret) {
+                args->op_ret = op_ret;
+                args->op_errno = op_errno;
+
+                if (peerinfo)
+                        peer_str = peerinfo->hostname;
+                else
+                        peer_str = uuid_utoa (uuid);
+
+                if (op_errstr && strcmp (op_errstr, ""))
+                        snprintf (err_str, sizeof(err_str) - 1,
+                                  "Error: %s", op_errstr);
+
+                switch (op_code) {
+                        case GLUSTERD_MGMT_V3_VOLUME_LOCK:
+                        {
+                                snprintf (op_err, sizeof(op_err) - 1,
+                                          "Locking volume failed "
+                                          "on %s. %s", peer_str, err_str);
+                                break;
+                        }
+                        case GLUSTERD_MGMT_V3_VOLUME_UNLOCK:
+                        {
+                                snprintf (op_err, sizeof(op_err) - 1,
+                                          "Unlocking volume failed "
+                                          "on %s. %s", peer_str, err_str);
+                                break;
+                        }
+                }
+
+                if (args->errstr) {
+                        snprintf (err_str, sizeof(err_str) - 1,
+                                  "%s\n%s", args->errstr,
+                                  op_err);
+                        GF_FREE (args->errstr);
+                        args->errstr = NULL;
+                } else
+                        snprintf (err_str, sizeof(err_str) - 1,
+                                  "%s", op_err);
+
+                gf_log ("", GF_LOG_ERROR, "%s", op_err);
+                args->errstr = gf_strdup (err_str);
+        }
+
+        return;
+}
+
+static void
 gd_collate_errors (struct syncargs *args, int op_ret, int op_errno,
                    char *op_errstr, int op_code,
                    glusterd_peerinfo_t *peerinfo, u_char *uuid)
@@ -207,6 +266,7 @@ out:
 /* Defined in glusterd-rpc-ops.c */
 extern struct rpc_clnt_program gd_mgmt_prog;
 extern struct rpc_clnt_program gd_brick_prog;
+extern struct rpc_clnt_program gd_mgmt_v3_prog;
 
 static int
 glusterd_syncop_aggr_rsp_dict (glusterd_op_t op, dict_t *aggr, dict_t *rsp)
@@ -287,6 +347,185 @@ out:
 }
 
 int32_t
+_gd_syncop_mgmt_volume_lock_cbk (struct rpc_req *req, struct iovec *iov,
+                                 int count, void *myframe)
+{
+        int                         ret         = -1;
+        struct syncargs             *args       = NULL;
+        glusterd_peerinfo_t         *peerinfo   = NULL;
+        gd1_mgmt_volume_lock_rsp     rsp        = {{0},};
+        call_frame_t                *frame      = NULL;
+        int                         op_ret      = -1;
+        int                         op_errno    = -1;
+
+        GF_ASSERT(req);
+        GF_ASSERT(iov);
+        GF_ASSERT(myframe);
+
+        frame  = myframe;
+        args   = frame->local;
+        peerinfo = frame->cookie;
+        frame->local = NULL;
+        frame->cookie = NULL;
+
+        if (-1 == req->rpc_status) {
+                op_errno = ENOTCONN;
+                goto out;
+        }
+
+        ret = xdr_to_generic (*iov, &rsp,
+                              (xdrproc_t)xdr_gd1_mgmt_volume_lock_rsp);
+        if (ret < 0)
+                goto out;
+
+        uuid_copy (args->uuid, rsp.uuid);
+
+        op_ret = rsp.op_ret;
+        op_errno = rsp.op_errno;
+out:
+        gd_mgmt_v3_collate_errors (args, op_ret, op_errno, NULL,
+                                   GLUSTERD_MGMT_V3_VOLUME_LOCK,
+                                   peerinfo, rsp.uuid);
+        STACK_DESTROY (frame->root);
+        synctask_barrier_wake(args);
+        return 0;
+}
+
+int32_t
+gd_syncop_mgmt_volume_lock_cbk (struct rpc_req *req, struct iovec *iov,
+                                int count, void *myframe)
+{
+        return glusterd_big_locked_cbk (req, iov, count, myframe,
+                                        _gd_syncop_mgmt_volume_lock_cbk);
+}
+
+int
+gd_syncop_mgmt_volume_lock (glusterd_op_t op, dict_t *op_ctx,
+                            glusterd_peerinfo_t *peerinfo,
+                            struct syncargs *args, uuid_t my_uuid,
+                            uuid_t recv_uuid, uuid_t txn_id)
+{
+        int                      ret  = -1;
+        gd1_mgmt_volume_lock_req req  = {{0},};
+        glusterd_conf_t         *conf = THIS->private;
+
+        GF_ASSERT(op_ctx);
+        GF_ASSERT(peerinfo);
+        GF_ASSERT(args);
+
+        ret = dict_allocate_and_serialize (op_ctx,
+                                           &req.dict.dict_val,
+                                           &req.dict.dict_len);
+        if (ret)
+                goto out;
+
+        uuid_copy (req.uuid, my_uuid);
+        uuid_copy (req.txn_id, txn_id);
+        req.op = op;
+        synclock_unlock (&conf->big_lock);
+        ret = gd_syncop_submit_request (peerinfo->rpc, &req, args, peerinfo,
+                                        &gd_mgmt_v3_prog,
+                                        GLUSTERD_MGMT_V3_VOLUME_LOCK,
+                                        gd_syncop_mgmt_volume_lock_cbk,
+                                        (xdrproc_t)
+                                        xdr_gd1_mgmt_volume_lock_req);
+        synclock_lock (&conf->big_lock);
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
+_gd_syncop_mgmt_volume_unlock_cbk (struct rpc_req *req, struct iovec *iov,
+                                   int count, void *myframe)
+{
+        int                         ret         = -1;
+        struct syncargs             *args       = NULL;
+        glusterd_peerinfo_t         *peerinfo   = NULL;
+        gd1_mgmt_volume_unlock_rsp   rsp        = {{0},};
+        call_frame_t                *frame      = NULL;
+        int                         op_ret      = -1;
+        int                         op_errno    = -1;
+
+        GF_ASSERT(req);
+        GF_ASSERT(iov);
+        GF_ASSERT(myframe);
+
+        frame  = myframe;
+        args   = frame->local;
+        peerinfo = frame->cookie;
+        frame->local = NULL;
+        frame->cookie = NULL;
+
+        if (-1 == req->rpc_status) {
+                op_errno = ENOTCONN;
+                goto out;
+        }
+
+        ret = xdr_to_generic (*iov, &rsp,
+                              (xdrproc_t)xdr_gd1_mgmt_volume_unlock_rsp);
+        if (ret < 0)
+                goto out;
+
+        uuid_copy (args->uuid, rsp.uuid);
+
+        /* Set peer as locked, so we unlock only the locked peers */
+        if (rsp.op_ret == 0)
+                peerinfo->locked = _gf_true;
+        op_ret = rsp.op_ret;
+        op_errno = rsp.op_errno;
+out:
+        gd_mgmt_v3_collate_errors (args, op_ret, op_errno, NULL,
+                                   GLUSTERD_MGMT_V3_VOLUME_UNLOCK,
+                                   peerinfo, rsp.uuid);
+        STACK_DESTROY (frame->root);
+        synctask_barrier_wake(args);
+        return 0;
+}
+
+int32_t
+gd_syncop_mgmt_volume_unlock_cbk (struct rpc_req *req, struct iovec *iov,
+                                  int count, void *myframe)
+{
+        return glusterd_big_locked_cbk (req, iov, count, myframe,
+                                        _gd_syncop_mgmt_volume_unlock_cbk);
+}
+
+int
+gd_syncop_mgmt_volume_unlock (dict_t *op_ctx, glusterd_peerinfo_t *peerinfo,
+                              struct syncargs *args, uuid_t my_uuid,
+                              uuid_t recv_uuid, uuid_t txn_id)
+{
+        int                          ret  = -1;
+        gd1_mgmt_volume_unlock_req   req  = {{0},};
+        glusterd_conf_t             *conf = THIS->private;
+
+        GF_ASSERT(op_ctx);
+        GF_ASSERT(peerinfo);
+        GF_ASSERT(args);
+
+        ret = dict_allocate_and_serialize (op_ctx,
+                                           &req.dict.dict_val,
+                                           &req.dict.dict_len);
+        if (ret)
+                goto out;
+
+        uuid_copy (req.uuid, my_uuid);
+        uuid_copy (req.txn_id, txn_id);
+        synclock_unlock (&conf->big_lock);
+        ret = gd_syncop_submit_request (peerinfo->rpc, &req, args, peerinfo,
+                                        &gd_mgmt_v3_prog,
+                                        GLUSTERD_MGMT_V3_VOLUME_UNLOCK,
+                                        gd_syncop_mgmt_volume_unlock_cbk,
+                                        (xdrproc_t)
+                                        xdr_gd1_mgmt_volume_unlock_req);
+        synclock_lock (&conf->big_lock);
+out:
+        gf_log ("", GF_LOG_DEBUG, "Returning %d", ret);
+        return ret;
+}
+
+int32_t
 _gd_syncop_mgmt_lock_cbk (struct rpc_req *req, struct iovec *iov,
                           int count, void *myframe)
 {
@@ -830,8 +1069,8 @@ gd_build_peers_list (struct list_head *peers, struct list_head *xact_peers,
 }
 
 int
-gd_lock_op_phase (struct list_head *peers, glusterd_op_t op, dict_t *op_ctx,
-                  char **op_errstr, int npeers)
+gd_lock_op_phase (glusterd_conf_t  *conf, glusterd_op_t op, dict_t *op_ctx,
+                  char **op_errstr, int npeers, uuid_t txn_id)
 {
         int                 ret         = -1;
         int                 peer_cnt    = 0;
@@ -839,6 +1078,9 @@ gd_lock_op_phase (struct list_head *peers, glusterd_op_t op, dict_t *op_ctx,
         xlator_t            *this       = NULL;
         glusterd_peerinfo_t *peerinfo   = NULL;
         struct syncargs     args        = {0};
+        struct list_head   *peers       = NULL;
+
+        peers = &conf->xaction_peers;
 
         if (!npeers) {
                 ret = 0;
@@ -849,22 +1091,38 @@ gd_lock_op_phase (struct list_head *peers, glusterd_op_t op, dict_t *op_ctx,
         synctask_barrier_init((&args));
         peer_cnt = 0;
         list_for_each_entry (peerinfo, peers, op_peers_list) {
-                /* Reset lock status */
-                peerinfo->locked = _gf_false;
-                gd_syncop_mgmt_lock (peerinfo, &args, MY_UUID, peer_uuid);
+                if (conf->op_version < GD_OP_VERSION_4) {
+                        /* Reset lock status */
+                        peerinfo->locked = _gf_false;
+                        gd_syncop_mgmt_lock (peerinfo, &args,
+                                             MY_UUID, peer_uuid);
+                } else
+                        gd_syncop_mgmt_volume_lock (op, op_ctx, peerinfo, &args,
+                                                    MY_UUID, peer_uuid, txn_id);
                 peer_cnt++;
         }
         gd_synctask_barrier_wait((&args), peer_cnt);
-        ret = args.op_ret;
-        if (ret) {
-                gf_asprintf (op_errstr, "Another transaction could be "
-                             "in progress. Please try again after "
-                             "sometime.");
-                gf_log (this->name, GF_LOG_ERROR, "Failed to acquire lock");
-                goto out;
+
+        if (args.op_ret) {
+                if (args.errstr)
+                         *op_errstr = gf_strdup (args.errstr);
+                else {
+                        ret = gf_asprintf (op_errstr, "Another transaction "
+                                           "could be in progress. Please try "
+                                           "again after sometime.");
+                        if (ret == -1)
+                                *op_errstr = NULL;
+
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Failed to acquire lock");
+
+                }
         }
 
-        ret = 0;
+        ret = args.op_ret;
+
+        gf_log (this->name, GF_LOG_DEBUG, "Sent lock op req for 'Volume %s' "
+                "to %d peers. Returning %d", gd_op_list[op], peer_cnt, ret);
 out:
         return ret;
 }
@@ -1055,9 +1313,10 @@ out:
 }
 
 int
-gd_unlock_op_phase (struct list_head *peers, glusterd_op_t op, int op_ret,
+gd_unlock_op_phase (glusterd_conf_t  *conf, glusterd_op_t op, int op_ret,
                     rpcsvc_request_t *req, dict_t *op_ctx, char *op_errstr,
-                    int npeers, gf_boolean_t is_locked)
+                    int npeers, char *volname, gf_boolean_t is_acquired,
+                    uuid_t txn_id)
 {
         glusterd_peerinfo_t *peerinfo   = NULL;
         glusterd_peerinfo_t *tmp        = NULL;
@@ -1066,6 +1325,9 @@ gd_unlock_op_phase (struct list_head *peers, glusterd_op_t op, int op_ret,
         int                 ret         = -1;
         xlator_t            *this       = NULL;
         struct syncargs     args        = {0};
+        struct list_head   *peers       = NULL;
+
+        peers = &conf->xaction_peers;
 
         if (!npeers) {
                 ret = 0;
@@ -1074,24 +1336,40 @@ gd_unlock_op_phase (struct list_head *peers, glusterd_op_t op, int op_ret,
 
         /* If the lock has not been held during this
          * transaction, do not send unlock requests */
-        if (!is_locked)
+        if (!is_acquired)
                 goto out;
 
         this = THIS;
         synctask_barrier_init((&args));
         peer_cnt = 0;
-        list_for_each_entry_safe (peerinfo, tmp, peers, op_peers_list) {
-                /* Only unlock peers that were locked */
-                if (peerinfo->locked) {
-                        gd_syncop_mgmt_unlock (peerinfo, &args, MY_UUID,
-                                               tmp_uuid);
-                        peer_cnt++;
+        if (conf->op_version < GD_OP_VERSION_4) {
+                list_for_each_entry_safe (peerinfo, tmp, peers, op_peers_list) {
+                        /* Only unlock peers that were locked */
+                        if (peerinfo->locked) {
+                                gd_syncop_mgmt_unlock (peerinfo, &args,
+                                                       MY_UUID, tmp_uuid);
+                                peer_cnt++;
+                                list_del_init (&peerinfo->op_peers_list);
+                        }
+                }
+        } else {
+                if (volname) {
+                        list_for_each_entry_safe (peerinfo, tmp,
+                                                  peers, op_peers_list) {
+                                gd_syncop_mgmt_volume_unlock (op_ctx, peerinfo,
+                                                              &args, MY_UUID,
+                                                              tmp_uuid, txn_id);
+                                peer_cnt++;
+                                list_del_init (&peerinfo->op_peers_list);
+                        }
                 }
-
-                list_del_init (&peerinfo->op_peers_list);
         }
         gd_synctask_barrier_wait((&args), peer_cnt);
+
         ret = args.op_ret;
+
+        gf_log (this->name, GF_LOG_DEBUG, "Sent unlock op req for 'Volume %s' "
+                "to %d peers. Returning %d", gd_op_list[op], peer_cnt, ret);
         if (ret) {
                 gf_log (this->name, GF_LOG_ERROR, "Failed to unlock "
                         "on some peer(s)");
@@ -1099,10 +1377,24 @@ gd_unlock_op_phase (struct list_head *peers, glusterd_op_t op, int op_ret,
 
 out:
         glusterd_op_send_cli_response (op, op_ret, 0, req, op_ctx, op_errstr);
-        /* Unlock and reset opinfo.op ONLY if lock ever succeeded! */
-        if (is_locked) {
+
+        if (is_acquired) {
+                /* Based on the op-version,
+                 * we release the cluster or volume lock
+                 * and clear the op */
+
                 glusterd_op_clear_op (op);
-                glusterd_unlock (MY_UUID);
+                if (conf->op_version < GD_OP_VERSION_4)
+                        glusterd_unlock (MY_UUID);
+                else {
+                        if (volname) {
+                                ret = glusterd_volume_unlock (volname, MY_UUID);
+                                if (ret)
+                                        gf_log (this->name, GF_LOG_ERROR,
+                                                "Unable to release lock for %s",
+                                                volname);
+                        }
+                }
         }
 
         return 0;
@@ -1120,7 +1412,8 @@ gd_get_brick_count (struct list_head *bricks)
 }
 
 int
-gd_brick_op_phase (glusterd_op_t op, dict_t *op_ctx, dict_t *req_dict, char **op_errstr)
+gd_brick_op_phase (glusterd_op_t op, dict_t *op_ctx, dict_t *req_dict,
+                   char **op_errstr)
 {
         glusterd_pending_node_t *pending_node = NULL;
         struct list_head        selected = {0,};
@@ -1192,21 +1485,43 @@ out:
 void
 gd_sync_task_begin (dict_t *op_ctx, rpcsvc_request_t * req)
 {
-        int                         ret             = -1;
-        int                         npeers          = 0;
-        dict_t                      *req_dict       = NULL;
-        glusterd_conf_t             *conf           = NULL;
-        glusterd_op_t               op              = 0;
-        int32_t                     tmp_op          = 0;
-        char                        *op_errstr      = NULL;
-        xlator_t                    *this           = NULL;
-        gf_boolean_t                is_locked       = _gf_false;
+        int                         ret              = -1;
+        int                         npeers           = 0;
+        dict_t                      *req_dict        = NULL;
+        glusterd_conf_t             *conf            = NULL;
+        glusterd_op_t               op               = 0;
+        int32_t                     tmp_op           = 0;
+        char                        *op_errstr       = NULL;
+        char                        *tmp             = NULL;
+        char                        *volname         = NULL;
+        xlator_t                    *this            = NULL;
+        gf_boolean_t                is_acquired      = _gf_false;
+        uuid_t                      *txn_id          = NULL;
+        glusterd_op_info_t          txn_opinfo;
 
         this = THIS;
         GF_ASSERT (this);
         conf = this->private;
         GF_ASSERT (conf);
 
+        /* Generate a transaction-id for this operation and
+         * save it in the dict */
+        ret = glusterd_generate_txn_id (op_ctx, &txn_id);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to generate transaction id");
+                goto out;
+
+        }
+
+        /* Save the MY_UUID as the originator_uuid */
+        ret = glusterd_set_originator_uuid (op_ctx);
+        if (ret) {
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Failed to set originator_uuid.");
+                goto out;
+        }
+
         ret = dict_get_int32 (op_ctx, GD_SYNC_OPCODE_KEY, &tmp_op);
         if (ret) {
                 gf_log (this->name, GF_LOG_ERROR, "Failed to get volume "
@@ -1215,28 +1530,73 @@ gd_sync_task_begin (dict_t *op_ctx, rpcsvc_request_t * req)
         }
 
         op = tmp_op;
-        ret = glusterd_lock (MY_UUID);
-        if (ret) {
-                gf_log (this->name, GF_LOG_ERROR, "Unable to acquire lock");
-                gf_asprintf (&op_errstr, "Another transaction is in progress. "
-                             "Please try again after sometime.");
-                goto out;
+
+        /* Based on the op_version, acquire a cluster or volume lock */
+        if (conf->op_version < GD_OP_VERSION_4) {
+                ret = glusterd_lock (MY_UUID);
+                if (ret) {
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to acquire lock");
+                        gf_asprintf (&op_errstr,
+                                     "Another transaction is in progress. "
+                                     "Please try again after sometime.");
+                        goto out;
+                }
+        } else {
+
+                /* If no volname is given as a part of the command, locks will
+                 * not be held */
+                ret = dict_get_str (op_ctx, "volname", &tmp);
+                if (ret) {
+                        gf_log ("", GF_LOG_DEBUG, "Failed to get volume "
+                                "name");
+                        goto local_locking_done;
+                } else {
+                        /* Use a copy of volname, as cli response will be
+                         * sent before the unlock, and the volname in the
+                         * dict, might be removed */
+                        volname = gf_strdup (tmp);
+                        if (!volname)
+                                goto out;
+                }
+
+                ret = glusterd_volume_lock (volname, MY_UUID);
+                if (ret) {
+                        gf_log (this->name, GF_LOG_ERROR,
+                                "Unable to acquire lock for %s", volname);
+                        gf_asprintf (&op_errstr,
+                                     "Another transaction is in progress "
+                                     "for %s. Please try again after sometime.",
+                                     volname);
+                        goto out;
+                }
         }
 
-        is_locked = _gf_true;
+        is_acquired = _gf_true;
+
+local_locking_done:
+
+        /* Save opinfo for this transaction with the transaction id */
+        glusterd_txn_opinfo_init (&txn_opinfo, NULL, &op, NULL, NULL);
+        ret = glusterd_set_txn_opinfo (txn_id, &txn_opinfo);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to set transaction's opinfo");
+
+        opinfo = txn_opinfo;
 
-        /* storing op globally to access in synctask code paths
-         * This is still acceptable, as we are performing this under
-         * the 'cluster' lock*/
-        glusterd_op_set_op  (op);
         INIT_LIST_HEAD (&conf->xaction_peers);
 
         npeers = gd_build_peers_list  (&conf->peers, &conf->xaction_peers, op);
 
-        ret = gd_lock_op_phase (&conf->xaction_peers, op, op_ctx, &op_errstr,
-                                npeers);
-        if (ret)
-                goto out;
+        /* If no volname is given as a part of the command, locks will
+         * not be held */
+        if (volname) {
+                ret = gd_lock_op_phase (conf, op, op_ctx, &op_errstr,
+                                        npeers, *txn_id);
+                if (ret)
+                        goto out;
+        }
 
         ret = glusterd_op_build_payload (&req_dict, &op_errstr, op_ctx);
         if (ret) {
@@ -1263,8 +1623,17 @@ gd_sync_task_begin (dict_t *op_ctx, rpcsvc_request_t * req)
 
         ret = 0;
 out:
-        (void) gd_unlock_op_phase (&conf->xaction_peers, op, ret, req,
-                                   op_ctx, op_errstr, npeers, is_locked);
+        (void) gd_unlock_op_phase (conf, op, ret, req, op_ctx, op_errstr,
+                                   npeers, volname, is_acquired, *txn_id);
+
+        /* Clearing the transaction opinfo */
+        ret = glusterd_clear_txn_opinfo (txn_id);
+        if (ret)
+                gf_log (this->name, GF_LOG_ERROR,
+                        "Unable to clear transaction's opinfo");
+
+        if (volname)
+                GF_FREE (volname);
 
         if (req_dict)
                 dict_unref (req_dict);
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index 78593d14e3b..ea26c4e475a 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -37,6 +37,7 @@
 #include "glusterd-pmap.h"
 #include "glusterfs-acl.h"
 #include "glusterd-syncop.h"
+#include "glusterd-locks.h"
 
 #include "xdr-generic.h"
 #include <sys/resource.h>
@@ -7897,7 +7898,7 @@ glusterd_volume_status_copy_to_op_ctx_dict (dict_t *aggr, dict_t *rsp_dict)
         if (ret)
                 goto out;
 
-        if (cmd & GF_CLI_STATUS_ALL && is_origin_glusterd ()) {
+        if (cmd & GF_CLI_STATUS_ALL && is_origin_glusterd (ctx_dict)) {
                 ret = dict_get_int32 (rsp_dict, "vol_count", &vol_count);
                 if (ret == 0) {
                         ret = dict_set_int32 (ctx_dict, "vol_count",
@@ -8788,20 +8789,66 @@ glusterd_handle_node_rsp (dict_t *req_dict, void *pending_entry,
         return ret;
 }
 
+int32_t
+glusterd_set_originator_uuid (dict_t *dict)
+{
+        int          ret              = -1;
+        uuid_t      *originator_uuid  = NULL;
+
+        GF_ASSERT (dict);
+
+        originator_uuid = GF_CALLOC (1, sizeof(uuid_t),
+                                     gf_common_mt_uuid_t);
+        if (!originator_uuid) {
+                ret = -1;
+                goto out;
+        }
+
+        uuid_copy (*originator_uuid, MY_UUID);
+        ret = dict_set_bin (dict, "originator_uuid",
+                            originator_uuid, sizeof (uuid_t));
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR,
+                        "Failed to set originator_uuid.");
+                goto out;
+        }
+
+out:
+        if (ret && originator_uuid)
+                GF_FREE (originator_uuid);
+
+        return ret;
+}
+
 /* Should be used only when an operation is in progress, as that is the only
  * time a lock_owner is set
  */
 gf_boolean_t
-is_origin_glusterd ()
+is_origin_glusterd (dict_t *dict)
 {
-        int     ret = 0;
-        uuid_t  lock_owner = {0,};
+        gf_boolean_t  ret              = _gf_false;
+        uuid_t        lock_owner       = {0,};
+        uuid_t        *originator_uuid = NULL;
 
-        ret = glusterd_get_lock_owner (&lock_owner);
-        if (ret)
-                return _gf_false;
+        GF_ASSERT (dict);
 
-        return (uuid_compare (MY_UUID, lock_owner) == 0);
+        ret = dict_get_bin (dict, "originator_uuid",
+                            (void **) &originator_uuid);
+        if (ret) {
+                /* If not originator_uuid has been set, then the command
+                 * has been originated from a glusterd running on older version
+                 * Hence fetching the lock owner */
+                ret = glusterd_get_lock_owner (&lock_owner);
+                if (ret) {
+                        ret = _gf_false;
+                        goto out;
+                }
+                ret = !uuid_compare (MY_UUID, lock_owner);
+        } else
+                ret = !uuid_compare (MY_UUID, *originator_uuid);
+
+out:
+        return ret;
 }
 
 int
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.h b/xlators/mgmt/glusterd/src/glusterd-utils.h
index 6b0d77b9f5d..cd22b29605a 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.h
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.h
@@ -529,11 +529,14 @@ glusterd_are_vol_all_peers_up (glusterd_volinfo_t *volinfo,
                                struct list_head *peers,
                                char **down_peerstr);
 
+int32_t
+glusterd_set_originator_uuid (dict_t *dict);
+
 /* Should be used only when an operation is in progress, as that is the only
  * time a lock_owner is set
  */
 gf_boolean_t
-is_origin_glusterd ();
+is_origin_glusterd (dict_t *dict);
 
 gf_boolean_t
 glusterd_is_quorum_changed (dict_t *options, char *option, char *value);
diff --git a/xlators/mgmt/glusterd/src/glusterd.c b/xlators/mgmt/glusterd/src/glusterd.c
index d59aaa44aae..9da8a29902c 100644
--- a/xlators/mgmt/glusterd/src/glusterd.c
+++ b/xlators/mgmt/glusterd/src/glusterd.c
@@ -36,6 +36,7 @@
 #include "glusterd-store.h"
 #include "glusterd-hooks.h"
 #include "glusterd-utils.h"
+#include "glusterd-locks.h"
 #include "common-utils.h"
 #include "run.h"
 
@@ -48,6 +49,7 @@ extern struct rpcsvc_program gluster_cli_getspec_prog;
 extern struct rpcsvc_program gluster_pmap_prog;
 extern glusterd_op_info_t opinfo;
 extern struct rpcsvc_program gd_svc_mgmt_prog;
+extern struct rpcsvc_program gd_svc_mgmt_v3_prog;
 extern struct rpcsvc_program gd_svc_peer_prog;
 extern struct rpcsvc_program gd_svc_cli_prog;
 extern struct rpcsvc_program gd_svc_cli_prog_ro;
@@ -64,6 +66,7 @@ struct rpcsvc_program *gd_inet_programs[] = {
         &gd_svc_peer_prog,
         &gd_svc_cli_prog_ro,
         &gd_svc_mgmt_prog,
+        &gd_svc_mgmt_v3_prog,
         &gluster_pmap_prog,
         &gluster_handshake_prog,
         &glusterd_mgmt_hndsk_prog,
@@ -1303,6 +1306,8 @@ init (xlator_t *this)
         glusterd_friend_sm_init ();
         glusterd_op_sm_init ();
         glusterd_opinfo_init ();
+        glusterd_vol_lock_init ();
+        glusterd_txn_opinfo_dict_init ();
         ret = glusterd_sm_tr_log_init (&conf->op_sm_log,
                                        glusterd_op_sm_state_name_get,
                                        glusterd_op_sm_event_name_get,
@@ -1422,6 +1427,8 @@ fini (xlator_t *this)
         if (conf->handle)
                 gf_store_handle_destroy (conf->handle);
         glusterd_sm_tr_log_delete (&conf->op_sm_log);
+        glusterd_vol_lock_fini ();
+        glusterd_txn_opinfo_dict_fini ();
         GF_FREE (conf);
 
         this->private = NULL;
diff --git a/xlators/mgmt/glusterd/src/glusterd.h b/xlators/mgmt/glusterd/src/glusterd.h
index 9b6e2fb3343..e8035c7c619 100644
--- a/xlators/mgmt/glusterd/src/glusterd.h
+++ b/xlators/mgmt/glusterd/src/glusterd.h
@@ -525,6 +525,14 @@ int
 glusterd_op_unlock_send_resp (rpcsvc_request_t *req, int32_t status);
 
 int
+glusterd_op_volume_lock_send_resp (rpcsvc_request_t *req,
+                                   uuid_t *txn_id, int32_t status);
+
+int
+glusterd_op_volume_unlock_send_resp (rpcsvc_request_t *req,
+                                     uuid_t *txn_id, int32_t status);
+
+int
 glusterd_op_stage_send_resp (rpcsvc_request_t *req,
                              int32_t op, int32_t status,
                              char *op_errstr, dict_t *rsp_dict);
@@ -797,4 +805,14 @@ int32_t glusterd_op_begin_synctask (rpcsvc_request_t *req, glusterd_op_t op,
                                     void *dict);
 int32_t
 glusterd_defrag_event_notify_handle (dict_t *dict);
+
+int32_t
+glusterd_txn_opinfo_dict_init ();
+
+void
+glusterd_txn_opinfo_dict_fini ();
+
+void
+glusterd_txn_opinfo_init ();
+
 #endif