glusterd: Improve rebalance handling during volume sync

        Backport of http://review.gluster.org/6334

Glusterd will now correctly copy existing rebalance information when a
volinfo is updated during volume sync. If the existing rebalance
information was stale, then any existing rebalance process will be
termimnated. A new rebalance process will be started only if there is no
existing rebalance process. The rebalance process will not be started if
the existing rebalance session had completed, failed or been stopped.

Change-Id: I68c5984267c188734da76770ba557662d4ea3ee0
BUG: 1036464
Signed-off-by: Kaushal M <kaushal@redhat.com>
Signed-off-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-on: http://review.gluster.org/6564
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

2 files changed, 200 insertions, 10 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.c b/xlators/mgmt/glusterd/src/glusterd-utils.c
index ad6731e626c..15c40f3e468 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.c
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.c
@@ -36,6 +36,7 @@
 #include "glusterd-volgen.h"
 #include "glusterd-pmap.h"
 #include "glusterfs-acl.h"
+#include "glusterd-syncop.h"
 
 #include "xdr-generic.h"
 #include <sys/resource.h>
@@ -587,6 +588,8 @@ glusterd_volinfo_delete (glusterd_volinfo_t *volinfo)
         if (volinfo->gsync_slaves)
                 dict_unref (volinfo->gsync_slaves);
         GF_FREE (volinfo->logdir);
+        if (volinfo->rebal.dict)
+                dict_unref (volinfo->rebal.dict);
 
         gf_store_handle_destroy (volinfo->quota_conf_shandle);
 
@@ -3322,6 +3325,50 @@ glusterd_delete_stale_volume (glusterd_volinfo_t *stale_volinfo,
         return 0;
 }
 
+/* This function updates the rebalance information of the new volinfo using the
+ * information from the old volinfo.
+ */
+int
+gd_check_and_update_rebalance_info (glusterd_volinfo_t *old_volinfo,
+                                    glusterd_volinfo_t *new_volinfo)
+{
+        int                  ret  = -1;
+        glusterd_rebalance_t *old = NULL;
+        glusterd_rebalance_t *new = NULL;
+
+        GF_ASSERT (old_volinfo);
+        GF_ASSERT (new_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 (uuid_compare (old->rebalance_id, new->rebalance_id)) {
+                (void)gd_stop_rebalance_process (old_volinfo);
+                goto out;
+        }
+
+        /* If the tasks match, copy the status and other information of the
+         * rebalance process from old_volinfo to new_volinfo
+         */
+        new->defrag_status      = old->defrag_status;
+        new->rebalance_files    = old->rebalance_files;
+        new->rebalance_data     = old->rebalance_data;
+        new->lookedup_files     = old->lookedup_files;
+        new->skipped_files      = old->skipped_files;
+        new->rebalance_failures = old->rebalance_failures;
+        new->rebalance_time     = old->rebalance_time;
+        new->defrag             = old->defrag;
+        new->dict               = (old->dict ? dict_ref (old->dict) : NULL);
+
+        /* glusterd_rebalance_t.{op, id, defrag_cmd} are copied during volume
+         * import
+         */
+out:
+        return ret;
+}
+
 int32_t
 glusterd_import_friend_volume (dict_t *vols, size_t count)
 {
@@ -3344,6 +3391,8 @@ glusterd_import_friend_volume (dict_t *vols, size_t count)
 
         ret = glusterd_volinfo_find (new_volinfo->volname, &old_volinfo);
         if (0 == ret) {
+                (void) gd_check_and_update_rebalance_info (old_volinfo,
+                                                           new_volinfo);
                 (void) glusterd_delete_stale_volume (old_volinfo, new_volinfo);
         }
 
@@ -6693,22 +6742,44 @@ int
 glusterd_volume_defrag_restart (glusterd_volinfo_t *volinfo, char *op_errstr,
                               size_t len, int cmd, defrag_cbk_fn_t cbk)
 {
-        glusterd_conf_t         *priv                   = NULL;
-        char                     pidfile[PATH_MAX];
-        int                      ret                    = -1;
-        pid_t                    pid;
+        xlator_t        *this             = NULL;
+        glusterd_conf_t *priv             = NULL;
+        char            pidfile[PATH_MAX] = {0,};
+        int             ret               = -1;
+        pid_t           pid               = 0;
 
-        priv = THIS->private;
+        this = THIS;
+        GF_ASSERT (this);
+
+        priv = this->private;
         if (!priv)
                 return ret;
 
-        GLUSTERD_GET_DEFRAG_PID_FILE(pidfile, volinfo, priv);
-
-        if (!gf_is_service_running (pidfile, &pid)) {
+        /* Don't start the rebalance process if the stautus is already
+         * completed, stopped or failed. If the status is started, check if
+         * there is an existing process already and connect to it. If not, then
+         * start the rebalance process
+         */
+        switch (volinfo->rebal.defrag_status) {
+        case GF_DEFRAG_STATUS_COMPLETE:
+        case GF_DEFRAG_STATUS_STOPPED:
+        case GF_DEFRAG_STATUS_FAILED:
+                break;
+        case GF_DEFRAG_STATUS_STARTED:
+                GLUSTERD_GET_DEFRAG_PID_FILE(pidfile, volinfo, priv);
+                if (gf_is_service_running (pidfile, &pid)) {
+                        glusterd_rebalance_rpc_create (volinfo);
+                        break;
+                }
+        case GF_DEFRAG_STATUS_NOT_STARTED:
                 glusterd_handle_defrag_start (volinfo, op_errstr, len, cmd,
                                               cbk, volinfo->rebal.op);
-        } else {
-                glusterd_rebalance_rpc_create (volinfo);
+                break;
+        default:
+                gf_log (this->name, GF_LOG_ERROR, "Unknown defrag status (%d)."
+                        "Not starting rebalance process for %s.",
+                        volinfo->rebal.defrag_status, volinfo->volname);
+                break;
         }
 
         return ret;
@@ -9071,3 +9142,119 @@ glusterd_remove_auxiliary_mount (char *volname)
         rmdir (mountdir);
         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
+ */
+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,};
+
+        GF_ASSERT (volinfo);
+
+        this = THIS;
+        GF_ASSERT (this);
+
+        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);
+
+        return ret;
+}
diff --git a/xlators/mgmt/glusterd/src/glusterd-utils.h b/xlators/mgmt/glusterd/src/glusterd-utils.h
index 7917fba197e..970b1f8a638 100644
--- a/xlators/mgmt/glusterd/src/glusterd-utils.h
+++ b/xlators/mgmt/glusterd/src/glusterd-utils.h
@@ -621,4 +621,7 @@ glusterd_remove_auxiliary_mount (char *volname);
 
 gf_boolean_t
 glusterd_status_has_tasks (int cmd);
+
+int
+gd_stop_rebalance_process (glusterd_volinfo_t *volinfo);
 #endif