cluster/dht: Add tier translator.

The tier translator shares most of DHT's code. It differs in how
subvolumes are chosen for I/Os, and how file migration (cache promotion
and demotion) is managed. That different functionality is split to either
DHT or tier logic according to the "tier_methods" structure.

A cache promotion and demotion thread is created in a manner
similar to the rebalance daemon. The thread operates a timing
wheel which periodically checks for promotion and demotion candidates
(files). Candidates are queued and then migrated. Candidates must exist on
the same node as the daemon and meet other critera per caching policies.

This patch has two authors (Dan Lambright and Joseph Fernandes). Dan
did the DHT changes and Joe wrote the cache policies. The fix depends on
DHT readidr changes and the database library which have been submitted
separately.  Header files in libglusterfs/src/gfdb should be reviewed in
patch 9683.

For more background and design see the feature page [1].

[1]
http://www.gluster.org/community/documentation/index.php/Features/data-classification

Change-Id: Icc26c517ccecf5c42aef039f5b9c6f7afe83e46c
BUG: 1194753
Signed-off-by: Dan Lambright <dlambrig@redhat.com>
Reviewed-on: http://review.gluster.org/9724
Reviewed-by: Vijay Bellur <vbellur@redhat.com>
Tested-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 82 insertions, 18 deletions

diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index 9fda4aa07d6..3a196e07be9 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -3175,6 +3175,7 @@ dht_setxattr (call_frame_t *frame, xlator_t *this,
         xlator_t     *subvol   = NULL;
         dht_local_t  *local    = NULL;
         dht_conf_t   *conf     = NULL;
+        dht_methods_t *methods = NULL;
         dht_layout_t *layout   = NULL;
         int           i        = 0;
         int           op_errno = EINVAL;
@@ -3191,6 +3192,10 @@ dht_setxattr (call_frame_t *frame, xlator_t *this,
         VALIDATE_OR_GOTO (loc->inode, err);
 
         conf   = this->private;
+        GF_VALIDATE_OR_GOTO (this->name, conf, err);
+
+        methods = conf->methods;
+        GF_VALIDATE_OR_GOTO (this->name, conf->methods, err);
 
         GF_IF_INTERNAL_XATTR_GOTO (conf->wild_xattr_name, xattr,
                                    op_errno, err);
@@ -3255,8 +3260,8 @@ dht_setxattr (call_frame_t *frame, xlator_t *this,
                         goto err;
                 }
 
-                local->rebalance.target_node =
-                        dht_subvol_get_hashed (this, &local->loc);
+                methods->migration_get_dst_subvol(this, local);
+
                 if (!local->rebalance.target_node) {
                         gf_msg (this->name, GF_LOG_ERROR, 0,
                                 DHT_MSG_HASHED_SUBVOL_GET_FAILED,
@@ -3719,7 +3724,6 @@ dht_statfs (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xdata)
         VALIDATE_OR_GOTO (frame, err);
         VALIDATE_OR_GOTO (this, err);
         VALIDATE_OR_GOTO (loc, err);
-        VALIDATE_OR_GOTO (loc->inode, err);
         VALIDATE_OR_GOTO (this->private, err);
 
         conf = this->private;
@@ -3730,7 +3734,7 @@ dht_statfs (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xdata)
                 goto err;
         }
 
-        if (IA_ISDIR (loc->inode->ia_type)) {
+        if (!loc->inode || IA_ISDIR (loc->inode->ia_type)) {
                 local->call_cnt = conf->subvolume_cnt;
 
                 for (i = 0; i < conf->subvolume_cnt; i++) {
@@ -3820,6 +3824,7 @@ dht_readdirp_cbk (call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,
         int           count = 0;
         dht_layout_t *layout = 0;
         dht_conf_t   *conf   = NULL;
+        dht_methods_t *methods = NULL;
         xlator_t     *subvol = 0;
         xlator_t     *hashed_subvol = 0;
         int           ret    = 0;
@@ -3828,7 +3833,12 @@ dht_readdirp_cbk (call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,
         INIT_LIST_HEAD (&entries.list);
         prev = cookie;
         local = frame->local;
+
         conf  = this->private;
+        GF_VALIDATE_OR_GOTO(this->name, conf, unwind);
+
+        methods = conf->methods;
+        GF_VALIDATE_OR_GOTO(this->name, conf->methods, done);
 
         if (op_ret < 0)
                 goto done;
@@ -3867,8 +3877,8 @@ dht_readdirp_cbk (call_frame_t *frame, void *cookie, xlator_t *this, int op_ret,
 
                         }
 
-                        hashed_subvol = dht_layout_search (this, layout, \
-                                                           orig_entry->d_name);
+                        hashed_subvol = methods->layout_search (this, layout,
+                                                         orig_entry->d_name);
 
                         if (prev->this == hashed_subvol)
                                 goto list;
@@ -3894,8 +3904,8 @@ list:
 
                 /* Do this if conf->search_unhashed is set to "auto" */
                 if (conf->search_unhashed == GF_DHT_LOOKUP_UNHASHED_AUTO) {
-                        subvol = dht_layout_search (this, layout,
-                                                    orig_entry->d_name);
+                        subvol = methods->layout_search (this, layout,
+                                                         orig_entry->d_name);
                         if (!subvol || (subvol != prev->this)) {
                                 /* TODO: Count the number of entries which need
                                    linkfile to prove its existence in fs */
@@ -4008,11 +4018,19 @@ dht_readdir_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         int           count = 0;
         dht_layout_t *layout = 0;
         xlator_t     *subvol = 0;
+        dht_conf_t   *conf = NULL;
+        dht_methods_t *methods = NULL;
 
         INIT_LIST_HEAD (&entries.list);
         prev = cookie;
         local = frame->local;
 
+        conf = this->private;
+        GF_VALIDATE_OR_GOTO (this->name, conf, done);
+
+        methods = conf->methods;
+        GF_VALIDATE_OR_GOTO (this->name, conf->methods, done);
+
         if (op_ret < 0)
                 goto done;
 
@@ -4024,7 +4042,8 @@ dht_readdir_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         list_for_each_entry (orig_entry, (&orig_entries->list), list) {
                 next_offset = orig_entry->d_off;
 
-                subvol = dht_layout_search (this, layout, orig_entry->d_name);
+                subvol = methods->layout_search (this, layout,
+                                                 orig_entry->d_name);
 
                 if (!subvol || (subvol == prev->this)) {
                         entry = gf_dirent_for_name (orig_entry->d_name);
@@ -6073,11 +6092,13 @@ dht_notify (xlator_t *this, int event, void *data, ...)
         gf_defrag_type           cmd    = 0;
         dict_t                  *output = NULL;
         va_list                  ap;
-
+        dht_methods_t           *methods = NULL;
 
         conf = this->private;
-        if (!conf)
-                return ret;
+        GF_VALIDATE_OR_GOTO (this->name, conf, out);
+
+        methods = conf->methods;
+        GF_VALIDATE_OR_GOTO (this->name, methods, out);
 
         /* had all subvolumes reported status once till now? */
         had_heard_from_all = 1;
@@ -6271,12 +6292,18 @@ unlock:
                  * not need to handle CHILD_DOWN event here.
                  */
                 if (conf->defrag) {
-                        ret = gf_thread_create (&conf->defrag->th, NULL,
-						gf_defrag_start, this);
-                        if (ret) {
-                                conf->defrag = NULL;
+                        if (methods->migration_needed(this)) {
+                                ret = gf_thread_create(&conf->defrag->th,
+                                                       NULL,
+                                                       gf_defrag_start, this);
+                                if (ret) {
+                                        GF_FREE (conf->defrag);
+                                        conf->defrag = NULL;
+                                        kill (getpid(), SIGTERM);
+                                }
+                        } else {
                                 GF_FREE (conf->defrag);
-                                kill (getpid(), SIGTERM);
+                                conf->defrag = NULL;
                         }
                 }
         }
@@ -6284,7 +6311,7 @@ unlock:
         ret = 0;
         if (propagate)
                 ret = default_notify (this, event, data);
-
+out:
         return ret;
 }
 
@@ -6412,3 +6439,40 @@ dht_log_new_layout_for_dir_selfheal (xlator_t *this, loc_t *loc,
 err:
         GF_FREE (output_string);
 }
+
+int32_t dht_migration_get_dst_subvol(xlator_t *this, dht_local_t  *local)
+{
+        int ret = -1;
+
+        if (!local)
+                goto out;
+
+        local->rebalance.target_node =
+                dht_subvol_get_hashed (this, &local->loc);
+
+        if (local->rebalance.target_node)
+                ret = 0;
+
+out:
+        return ret;
+}
+
+int32_t dht_migration_needed(xlator_t *this)
+{
+        gf_defrag_info_t        *defrag = NULL;
+        dht_conf_t              *conf   = NULL;
+        int                      ret = 0;
+
+        conf = this->private;
+
+        GF_VALIDATE_OR_GOTO ("dht", conf, out);
+        GF_VALIDATE_OR_GOTO ("dht", conf->defrag, out);
+
+        defrag = conf->defrag;
+
+        if (defrag->cmd != GF_DEFRAG_CMD_START_TIER)
+                ret = 1;
+
+out:
+        return ret;
+}