cluster/dht: Bring option to choose gfid or name based hashing

Change-Id: I11794eb2adceb88e75864aede450e904431a6273
BUG: 1095888
Signed-off-by: Venkatesh Somyajulu <vsomyaju@redhat.com>
Reviewed-on: http://review.gluster.org/8049
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

3 files changed, 32 insertions, 5 deletions

diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index 6fa5b91d97d..e1e3a5a4e38 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -303,6 +303,7 @@ struct dht_conf {
         char            *xattr_name;
         char            *link_xattr_name;
         char            *wild_xattr_name;
+        gf_boolean_t    randomize_by_gfid;
 };
 typedef struct dht_conf dht_conf_t;
 
diff --git a/xlators/cluster/dht/src/dht-selfheal.c b/xlators/cluster/dht/src/dht-selfheal.c
index 84b0f2f4679..04e58903147 100644
--- a/xlators/cluster/dht/src/dht-selfheal.c
+++ b/xlators/cluster/dht/src/dht-selfheal.c
@@ -566,16 +566,26 @@ dht_selfheal_dir_mkdir (call_frame_t *frame, loc_t *loc,
         return 0;
 }
 
-
 int
 dht_selfheal_layout_alloc_start (xlator_t *this, loc_t *loc,
                                  dht_layout_t *layout)
 {
-        int           start = 0;
-        uint32_t      hashval = 0;
-        int           ret = 0;
+        int         start                               = 0;
+        uint32_t    hashval                             = 0;
+        int         ret                                 = 0;
+        const char *str                                 = NULL;
+        dht_conf_t *conf                                = NULL;
+        char           buf[UUID_CANONICAL_FORM_LEN + 1] = {0, };
+
+        conf = this->private;
+
+        if (conf->randomize_by_gfid) {
+                str = uuid_utoa_r (loc->gfid, buf);
+        } else {
+                str = loc->path;
+        }
 
-        ret = dht_hash_compute (this, layout->type, loc->path, &hashval);
+        ret = dht_hash_compute (this, layout->type, str, &hashval);
         if (ret == 0) {
                 start = (hashval % layout->cnt);
         }
diff --git a/xlators/cluster/dht/src/dht-shared.c b/xlators/cluster/dht/src/dht-shared.c
index 3d1d635b4ed..53082c505ff 100644
--- a/xlators/cluster/dht/src/dht-shared.c
+++ b/xlators/cluster/dht/src/dht-shared.c
@@ -395,6 +395,10 @@ dht_reconfigure (xlator_t *this, dict_t *options)
 
         GF_OPTION_RECONF ("readdir-optimize", conf->readdir_optimize, options,
                           bool, out);
+        GF_OPTION_RECONF ("randomize-hash-range-by-gfid",
+                          conf->randomize_by_gfid,
+                          options, bool, out);
+
         if (conf->defrag) {
                 GF_OPTION_RECONF ("rebalance-stats", conf->defrag->stats,
                                   options, bool, out);
@@ -643,6 +647,9 @@ dht_init (xlator_t *this)
                 goto err;
         }
 
+        GF_OPTION_INIT ("randomize-hash-range-by-gfid",
+                        conf->randomize_by_gfid, bool, err);
+
         GF_OPTION_INIT ("xattr-name", conf->xattr_name, str, err);
         gf_asprintf (&conf->link_xattr_name, "%s."DHT_LINKFILE_STR,
                      conf->xattr_name);
@@ -793,5 +800,14 @@ struct volume_options options[] = {
           .type = GF_OPTION_TYPE_ANY
         },
 
+        { .key =  {"randomize-hash-range-by-gfid"},
+          .type = GF_OPTION_TYPE_BOOL,
+          .default_value = "off",
+          .description = "Use gfid of directory to determine the subvolume "
+          "from which hash ranges are allocated starting with 0. "
+          "Note that we still use a directory/file's name to determine the "
+          "subvolume to which it hashes"
+        },
+
         { .key  = {NULL} },
 };