cluster/tier: add pause tier for snapshots

This is a backport of 12304

Snaps of tiered volumes cannot handle files undergoing migration.
We implement a helper mechanism to "pause" migration. Any files
undergoing migration are aborted. Clean up is done to remove
sticky bits and data at the destination. Migration is restarted
after snap completes.

For testing an internal switch is added. It is not exposed externally.

gluster volume set vol1 tier-pause [true|false]

> Change-Id: Ia85bbf89ac142e9b7e73fcbef98bb9da86097799
> BUG: 1267950
> Signed-off-by: Dan Lambright <dlambrig@redhat.com>
> Reviewed-on: http://review.gluster.org/12304
> Reviewed-by: N Balachandran <nbalacha@redhat.com>
> Tested-by: NetBSD Build System <jenkins@build.gluster.org>
> Tested-by: Gluster Build System <jenkins@build.gluster.com>
Signed-off-by: Dan Lambright <dlambrig@redhat.com>

Conflicts:
	xlators/mgmt/glusterd/src/glusterd-messages.h

Change-Id: I5f039d8d38a4c915bd873969f336b96755a0b8f1
BUG: 1274101
Reviewed-on: http://review.gluster.org/12411
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>
Tested-by: Dan Lambright <dlambrig@redhat.com>

1 files changed, 67 insertions, 1 deletions

diff --git a/xlators/cluster/dht/src/tier.c b/xlators/cluster/dht/src/tier.c
index efdc57fe644..ecb8709547c 100644
--- a/xlators/cluster/dht/src/tier.c
+++ b/xlators/cluster/dht/src/tier.c
@@ -311,6 +311,13 @@ tier_migrate_using_query_file (void *_args)
                 per_file_status      = 0;
                 per_link_status      = 0;
 
+                if (defrag->tier_conf.request_pause) {
+                        gf_msg (this->name, GF_LOG_INFO, 0,
+                                DHT_MSG_LOG_TIER_STATUS,
+                                "Tiering paused. Exiting tier_migrate_using_query_file");
+                        break;
+                }
+
                 memset (gfid_str, 0, UUID_CANONICAL_FORM_LEN+1);
                 memset (query_record->_link_info_str, 0, DB_QUERY_RECORD_SIZE);
 
@@ -372,6 +379,14 @@ tier_migrate_using_query_file (void *_args)
                 /* Per link of file */
                 while (token_str != NULL) {
 
+                        if (defrag->tier_conf.request_pause) {
+                                gf_msg (this->name, GF_LOG_INFO, 0,
+                                        DHT_MSG_LOG_TIER_STATUS,
+                                        "Tiering paused. "
+                                        "Exiting tier_migrate_using_query_file");
+                                goto abort;
+                        }
+
                         link_str = gf_strdup (token_str);
 
                         if (!link_info) {
@@ -489,6 +504,14 @@ tier_migrate_using_query_file (void *_args)
 
                         gf_uuid_copy (loc.gfid, loc.inode->gfid);
 
+                        if (defrag->tier_conf.request_pause) {
+                                gf_msg (this->name, GF_LOG_INFO, 0,
+                                        DHT_MSG_LOG_TIER_STATUS,
+                                        "Tiering paused. "
+                                        "Exiting tier_migrate_using_query_file");
+                                goto abort;
+                        }
+
                         ret = syncop_setxattr (this, &loc, migrate_data, 0,
                                                NULL, NULL);
                         if (ret) {
@@ -1348,6 +1371,11 @@ tier_start (xlator_t *this, gf_defrag_info_t *defrag)
                         goto out;
                 }
 
+                if (defrag->tier_conf.request_pause)
+                        defrag->tier_conf.paused = _gf_true;
+                else
+                        defrag->tier_conf.paused = _gf_false;
+
                 sleep(1);
 
                 if (defrag->defrag_status != GF_DEFRAG_STATUS_STARTED) {
@@ -1370,6 +1398,11 @@ tier_start (xlator_t *this, gf_defrag_info_t *defrag)
                         goto out;
                 }
 
+                if ((defrag->tier_conf.paused) ||
+                    (defrag->tier_conf.request_pause))
+                        continue;
+
+
                 /* To have proper synchronization amongst all
                  * brick holding nodes, so that promotion and demotions
                  * start atomicly w.r.t promotion/demotion frequency
@@ -1660,6 +1693,7 @@ tier_init (xlator_t *this)
         gf_defrag_info_t *defrag         = NULL;
         char             *voldir         = NULL;
         char             *mode           = NULL;
+        char             *paused         = NULL;
 
         ret = dht_init (this);
         if (ret) {
@@ -1778,7 +1812,15 @@ tier_init (xlator_t *this)
                 defrag->tier_conf.mode = ret;
         }
 
-        ret = gf_asprintf (&voldir, "%s/%s",
+        defrag->tier_conf.request_pause = 0;
+
+        ret = dict_get_str (this->options,
+                              "tier-pause", &paused);
+
+        if (paused && strcmp (paused, "on") == 0)
+                defrag->tier_conf.request_pause = 1;
+
+        ret = gf_asprintf(&voldir, "%s/%s",
                           DEFAULT_VAR_RUN_DIRECTORY,
                           this->name);
         if (ret < 0)
@@ -1846,6 +1888,9 @@ tier_reconfigure (xlator_t *this, dict_t *options)
         gf_defrag_info_t *defrag         = NULL;
         char             *mode           = NULL;
         int               migrate_mb     = 0;
+        gf_boolean_t      req_pause      = _gf_false;
+        int               ret            = 0;
+
         conf = this->private;
 
         if (conf->defrag) {
@@ -1887,6 +1932,27 @@ tier_reconfigure (xlator_t *this, dict_t *options)
                 GF_OPTION_RECONF ("tier-max-files",
                                   defrag->tier_conf.max_migrate_files, options,
                                   int32, out);
+
+                GF_OPTION_RECONF ("tier-pause",
+                                  req_pause, options,
+                                  bool, out);
+
+                if (req_pause == _gf_true) {
+                        ret = gf_defrag_pause_tier (this, defrag);
+                        if (ret) {
+                                gf_msg (this->name, GF_LOG_ERROR, 0,
+                                        DHT_MSG_LOG_TIER_ERROR,
+                                        "pause tier failed on reconfigure");
+                        }
+                } else {
+                        ret = gf_defrag_resume_tier (this, defrag);
+                        if (ret) {
+                                gf_msg (this->name, GF_LOG_ERROR, 0,
+                                        DHT_MSG_LOG_TIER_ERROR,
+                                        "resume tier failed on reconfigure");
+                        }
+                }
+
         }
 
 out: