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, 14 insertions, 0 deletions

diff --git a/xlators/cluster/dht/src/dht-selfheal.c b/xlators/cluster/dht/src/dht-selfheal.c
index 882e0209e..1c881be39 100644
--- a/xlators/cluster/dht/src/dht-selfheal.c
+++ b/xlators/cluster/dht/src/dht-selfheal.c
@@ -460,8 +460,22 @@ static inline int
 dht_get_layout_count (xlator_t *this, dht_layout_t *layout, int new_layout)
 {
         int i = 0;
+        int j = 0;
         int err = 0;
         int count = 0;
+        dht_conf_t *conf = NULL;
+
+        /* Gets in use only for replace-brick, remove-brick */
+        conf = this->private;
+        for (i = 0; i < layout->cnt; i++) {
+                for (j = 0; j < conf->subvolume_cnt; j++) {
+                        if (conf->decommissioned_bricks[j] &&
+                            conf->decommissioned_bricks[j] == layout->list[i].xlator) {
+                                layout->list[i].err = -EINVAL;
+                                break;
+                        }
+                }
+        }
 
         for (i = 0; i < layout->cnt; i++) {
                 err = layout->list[i].err;