glusterd: Fix stopping of stale rebalance processes

        Backport of http://review.gluster.org/6531

Trying to stop rebalance process via RPC using the GD_SYNCOP macro,
could lead to glusterd crashing. In case of an implicit volume update,
which happens when a peer comes back up, the stop function would be
called in the epoll thread. This would lead to glusterd crashing as the
epoll thread doesn't have synctasks for the GD_SYNCOP macro to make use
of.

Instead of using the RPC method, we now terminate the rebalance process
by kill(). The rebalance process has been designed to be resistant to
interruption, so this will not lead to any data corruption.

Also, when checking for stale rebalance task, make sure that the old
task-id is not null.

Change-Id: I54dd93803954ee55316cc58b5877f38d1ebc40b9
BUG: 1044327
Signed-off-by: Kaushal M <kaushal@redhat.com>
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/6567
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 12 insertions, 102 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index fb1fed3a4a2..9b5371231a7 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -3412,10 +3412,12 @@ gd_check_and_update_rebalance_info (glusterd_volinfo_t *old_volinfo,
 
         old = &(old_volinfo->rebal);
         new = &(new_volinfo->rebal);
-        /* If the task-id's don't match, the old volinfo task is stale and
-         * should be cleaned up
+
+        /* If the old task-id is not null and the task-id's don't match, the old
+         * volinfo task is stale and should be cleaned up
          */
-        if (uuid_compare (old->rebalance_id, new->rebalance_id)) {
+        if (!uuid_is_null (old->rebalance_id) &&
+            uuid_compare (old->rebalance_id, new->rebalance_id)) {
                 (void)gd_stop_rebalance_process (old_volinfo);
                 goto out;
         }
@@ -9215,72 +9217,15 @@ glusterd_remove_auxiliary_mount (char *volname)
         return ret;
 }
 
-/* Just a minimal callback function to which logs if the request was successfull
- * or not
- */
-int
-_gd_stop_rebalance_process_cbk (struct rpc_req *req, struct iovec *iov,
-                                int count, void *call_frame)
-{
-        xlator_t              *this  = NULL;
-        struct syncargs       *args  = NULL;
-        gd1_mgmt_brick_op_rsp rsp    = {0,};
-        int                   ret    = -1;
-        call_frame_t          *frame = NULL;
-
-        this = THIS;
-        GF_ASSERT (this);
-
-        frame = call_frame;
-        args = frame->local;
-        frame->local = NULL;
-
-        if (-1 == req->rpc_status) {
-                gf_log (this->name, GF_LOG_WARNING, "Failed to stop rebalance "
-                        "process.");
-                goto out;
-        }
-
-        ret = xdr_to_generic (*iov, &rsp, (xdrproc_t)xdr_gd1_mgmt_brick_op_rsp);
-        if (ret < 0) {
-                gf_log (this->name, GF_LOG_DEBUG, "Failed to decode stop "
-                        "rebalance process response.");
-                goto out;
-        }
-
-        gf_log (this->name, GF_LOG_INFO, "Stopping rebalance process was %s.",
-                (rsp.op_ret ? "unsuccessful" : "successful"));
-
-out:
-        if ((rsp.op_errstr) && (strcmp (rsp.op_errstr, "") != 0))
-                free (rsp.op_errstr);
-        free (rsp.output.output_val);
-
-        STACK_DESTROY (frame->root);
-        __wake (args);
-
-        return 0;
-}
-
-int
-gd_stop_rebalance_process_cbk (struct rpc_req *req, struct iovec *iov,
-                                int count, void *call_frame)
-{
-        return glusterd_big_locked_cbk (req, iov, count, call_frame,
-                                        _gd_stop_rebalance_process_cbk);
-}
-/* Stops the rebalance process of the given volume, gracefully
+/* Stops the rebalance process of the given volume
  */
 int
 gd_stop_rebalance_process (glusterd_volinfo_t *volinfo)
 {
-        int                   ret       = -1;
-        xlator_t              *this     = NULL;
-        glusterd_conf_t       *conf     = NULL;
-        gd1_mgmt_brick_op_req *req      = NULL;
-        dict_t                *req_dict = NULL;
-        char                  *name     = NULL;
-        struct syncargs       args      = {0,};
+        int              ret               = -1;
+        xlator_t        *this              = NULL;
+        glusterd_conf_t *conf              = NULL;
+        char             pidfile[PATH_MAX] = {0,};
 
         GF_ASSERT (volinfo);
 
@@ -9290,43 +9235,8 @@ gd_stop_rebalance_process (glusterd_volinfo_t *volinfo)
         conf = this->private;
         GF_ASSERT (conf);
 
-        req = GF_CALLOC (1, sizeof (*req), gf_gld_mt_mop_brick_req_t);
-        if (!req) {
-                ret = -1;
-                goto out;
-        }
-
-        req->op = GLUSTERD_BRICK_XLATOR_DEFRAG;
-
-        ret = gf_asprintf(&name, "%s-dht", volinfo->volname);
-        if (ret < 0)
-                goto out;
-        req->name = name;
-
-        req_dict = dict_new();
-        if (!req_dict) {
-                ret = -1;
-                goto out;
-        }
-
-        ret = dict_set_int32 (req_dict, "rebalance-command",
-                              GF_DEFRAG_CMD_STOP);
-        if (ret)
-                goto out;
-
-        ret = dict_allocate_and_serialize (req_dict, &req->input.input_val,
-                                           &req->input.input_len);
-        if (ret)
-                goto out;
-
-        GD_SYNCOP (volinfo->rebal.defrag->rpc, (&args), NULL,
-                   gd_stop_rebalance_process_cbk, req, conf->gfs_mgmt, req->op,
-                   (xdrproc_t)xdr_gd1_mgmt_brick_op_req);
-out:
-
-        GF_FREE (name);
-        GF_FREE (req);
-        dict_unref (req_dict);
+        GLUSTERD_GET_DEFRAG_PID_FILE (pidfile, volinfo, conf);
+        ret = glusterd_service_stop ("rebalance", pidfile, SIGTERM, _gf_true);
 
         return ret;
 }