support for de-commissioning a node using 'remove-brick'

to achieve this, we now create volume-file with
'decommissioned-nodes' option in distribute volume, then just
perform the rebalance set of operations (with 'force' flag set).

now onwards, the 'remove-brick' (with 'start' option) operation tries
to migrate data from removed bricks to existing bricks.

'remove-brick' also supports similar options as of replace-brick.

* (no options) -> works as 'force', will have the current behavior
         of remove-brick, ie., no data-migration, volume changes.

* start  (starts remove-brick with data-migration/draining process,
          which takes care of migrating data and once complete, will
          commit the changes to volume file)
* pause  (stop data migration, but keep the volume file intact with
          extra options whatever is set)
* abort  (stop data-migration, and fall back to old configuration)
* commit (if volume is stopped, commits the changes to volumefile)
* force  (stops the data-migration and commits the changes to
          volume file)

Change-Id: I3952bcfbe604a0952e68b6accace7014d5e401d3
BUG: 1952
Reviewed-on: http://review.gluster.com/118
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vijay@gluster.com>

1 files changed, 56 insertions, 6 deletions

diff --git a/xlators/cluster/dht/src/dht.c b/xlators/cluster/dht/src/dht.c
index 87a5756546f..d9499a407a6 100644
--- a/xlators/cluster/dht/src/dht.c
+++ b/xlators/cluster/dht/src/dht.c
@@ -255,6 +255,47 @@ out:
 
 
 int
+dht_parse_decommissioned_bricks (xlator_t *this, dht_conf_t *conf,
+                                 const char *bricks)
+{
+        int         i  = 0;
+        int         ret  = -1;
+        char       *tmpstr = NULL;
+        char       *dup_brick = NULL;
+        char       *node = NULL;
+
+        if (!conf || !bricks)
+                goto out;
+
+        dup_brick = gf_strdup (bricks);
+        node = strtok_r (dup_brick, ",", &tmpstr);
+        while (node) {
+                for (i = 0; i < conf->subvolume_cnt; i++) {
+                        if (!strcmp (conf->subvolumes[i]->name, node)) {
+                                conf->decommissioned_bricks[i] =
+                                        conf->subvolumes[i];
+                                gf_log (this->name, GF_LOG_INFO,
+                                        "decommissioning subvolume %s",
+                                        conf->subvolumes[i]->name);
+                                break;
+                        }
+                }
+                if (i == conf->subvolume_cnt) {
+                        /* Wrong node given. */
+                        goto out;
+                }
+                node = strtok_r (NULL, ",", &tmpstr);
+        }
+
+        ret = 0;
+out:
+        if (dup_brick)
+                GF_FREE (dup_brick);
+
+        return ret;
+}
+
+int
 reconfigure (xlator_t *this, dict_t *options)
 {
         dht_conf_t      *conf = NULL;
@@ -299,6 +340,12 @@ reconfigure (xlator_t *this, dict_t *options)
         GF_OPTION_RECONF ("directory-layout-spread", conf->dir_spread_cnt,
                           options, uint32, out);
 
+        if (dict_get_str (options, "decommissioned-bricks", &temp_str) == 0) {
+                ret = dht_parse_decommissioned_bricks (this, conf, temp_str);
+                if (ret == -1)
+                        goto out;
+        }
+
         ret = 0;
 out:
         return ret;
@@ -360,14 +407,14 @@ init (xlator_t *this)
                 goto err;
         }
 
-        ret = dht_layouts_init (this, conf);
-        if (ret == -1) {
-                goto err;
+        if (dict_get_str (this->options, "decommissioned-bricks", &temp_str) == 0) {
+                ret = dht_parse_decommissioned_bricks (this, conf, temp_str);
+                if (ret == -1)
+                        goto err;
         }
 
-        conf->du_stats = GF_CALLOC (conf->subvolume_cnt, sizeof (dht_du_t),
-                                    gf_dht_mt_dht_du_t);
-        if (!conf->du_stats) {
+        ret = dht_layouts_init (this, conf);
+        if (ret == -1) {
                 goto err;
         }
 
@@ -501,5 +548,8 @@ struct volume_options options[] = {
         { .key  = {"directory-layout-spread"},
           .type = GF_OPTION_TYPE_INT,
         },
+        { .key  = {"decommissioned-bricks"},
+          .type = GF_OPTION_TYPE_ANY,
+        },
         { .key  = {NULL} },
 };