glusterd: support for tier volumes 'detach start' and 'detach commit'

These commands work in a manner analagous to rebalancing when removing a
brick. The existing migration daemon detects "detach start" and switches
to moving data off the hot tier. While in this state all lookups are
directed to the cold tier.

gluster v detach-tier <vol> start
gluster v detach-tier <vol> commit

The status and stop cli commands shall be submitted separately.

Change-Id: I24fda5cc3ba74f5fb8aa9a3234ad51f18b80a8a0
BUG: 1205540
Signed-off-by: Dan Lambright <dlambrig@redhat.com>
Signed-off-by: root <root@localhost.localdomain>
Signed-off-by: Dan Lambright <dlambrig@redhat.com>
Reviewed-on: http://review.gluster.org/10108
Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>
Tested-by: NetBSD Build System

1 files changed, 30 insertions, 8 deletions

diff --git a/xlators/cluster/dht/src/tier.c b/xlators/cluster/dht/src/tier.c
index cf481c5e7f2..5c3c3aa5548 100644
--- a/xlators/cluster/dht/src/tier.c
+++ b/xlators/cluster/dht/src/tier.c
@@ -794,6 +794,15 @@ tier_start (xlator_t *this, gf_defrag_info_t *defrag)
                         goto out;
                 }
 
+                if (defrag->cmd == GF_DEFRAG_CMD_START_DETACH_TIER) {
+                        ret = 1;
+                        gf_msg (this->name, GF_LOG_ERROR, 0,
+                                DHT_MSG_LOG_TIER_ERROR,
+                                "defrag->defrag_cmd == "
+                                "GF_DEFRAG_CMD_START_DETACH_TIER");
+                        goto out;
+                }
+
                 tick = (tick + 1) % TIMER_SECS;
                 if ((next_demote != tick) && (next_promote != tick))
                         continue;
@@ -893,15 +902,19 @@ tier_migration_get_dst (xlator_t *this, dht_local_t *local)
 {
         dht_conf_t              *conf   = NULL;
         int32_t                  ret = -1;
+        gf_defrag_info_t        *defrag = NULL;
 
         GF_VALIDATE_OR_GOTO("tier", this, out);
         GF_VALIDATE_OR_GOTO(this->name, this->private, out);
 
         conf = this->private;
-        if (!conf)
-                goto out;
 
-        if (conf->subvolumes[0] == local->cached_subvol)
+        defrag = conf->defrag;
+
+        if (defrag && defrag->cmd == GF_DEFRAG_CMD_START_DETACH_TIER) {
+                local->rebalance.target_node = conf->subvolumes[0];
+
+        } else if (conf->subvolumes[0] == local->cached_subvol)
                 local->rebalance.target_node =
                         conf->subvolumes[1];
         else
@@ -918,16 +931,25 @@ out:
 xlator_t *
 tier_search (xlator_t *this, dht_layout_t *layout, const char *name)
 {
-        xlator_t  *subvol = NULL;
-        void      *value;
-        int        search_first_subvol = 0;
+        xlator_t                *subvol = NULL;
+        void                    *value;
+        int                      search_first_subvol = 0;
+        dht_conf_t              *conf   = NULL;
+        gf_defrag_info_t        *defrag = NULL;
 
         GF_VALIDATE_OR_GOTO("tier", this, out);
         GF_VALIDATE_OR_GOTO(this->name, layout, out);
         GF_VALIDATE_OR_GOTO(this->name, name, out);
+        GF_VALIDATE_OR_GOTO(this->name, this->private, out);
+
+        conf = this->private;
+
+        defrag = conf->defrag;
+        if (defrag && defrag->cmd == GF_DEFRAG_CMD_START_DETACH_TIER)
+                search_first_subvol = 1;
 
-        if (!dict_get_ptr (this->options, "rule", &value) &&
-            !strcmp(layout->list[0].xlator->name, value)) {
+        else if (!dict_get_ptr (this->options, "rule", &value) &&
+                 !strcmp(layout->list[0].xlator->name, value)) {
                 search_first_subvol = 1;
         }