features/shard: Introducing sharding translator

Based on the high-level design by Anand V. Avati which can be found @
https://gist.github.com/avati/af04f1030dcf52e16535#sharding-xlator-stripe-20

Still to-do:
        * complete implementation of inode write fops - [f]truncate,
          zerofill, fallocate, discard
        * introduce transaction mechanism in inode write fops
        * complete readv
        * Handle open with O_TRUNC
        * Handle unlinking of all shards during unlink/rename
        * Compute total ia_size and ia_blocks in lookup, readdirp, etc
        * wind fsync/flush on all shards

        Note: Most of the items above are related. Once we come up
        with a clean way to determine the last shard/shard count for
        a file/file size and the mgmt of sparse regions of the file,
        implementing them becomes trivial.

Change-Id: Id871379b53a4a916e4baa2e06f197dd8c0043b0f
BUG: 1200082
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/9841
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

2 files changed, 23 insertions, 1 deletions

diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.c b/xlators/mgmt/glusterd/src/glusterd-volgen.c
index 6f6d1095edb..b098a297132 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.c
@@ -3353,6 +3353,18 @@ client_graph_builder (volgen_graph_t *graph, glusterd_volinfo_t *volinfo,
         if (ret == -1)
                 goto out;
 
+        ret = dict_get_str_boolean (set_dict, "features.shard", _gf_false);
+        if (ret == -1)
+                goto out;
+
+        if (ret) {
+                xl = volgen_graph_add (graph, "features/shard", volname);
+                if (!xl) {
+                        ret = -1;
+                        goto out;
+                }
+        }
+
         /* As of now snapshot volume is read-only. Read-only xlator is loaded
          * in client graph so that AFR & DHT healing can be done in server.
          */
@@ -3388,7 +3400,6 @@ client_graph_builder (volgen_graph_t *graph, glusterd_volinfo_t *volinfo,
                 goto out;
         if (ret) {
                 xl = volgen_graph_add (graph, "encryption/crypt", volname);
-
                 if (!xl) {
                         ret = -1;
                         goto out;
diff --git a/xlators/mgmt/glusterd/src/glusterd-volume-set.c b/xlators/mgmt/glusterd/src/glusterd-volume-set.c
index ada814bb25d..68e3fb7d46b 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volume-set.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volume-set.c
@@ -1763,6 +1763,17 @@ struct volopt_map_entry glusterd_volopt_map[] = {
           .type        = NO_DOC,
           .op_version  = GD_OP_VERSION_3_7_0,
         },
+        { .key        = "features.shard",
+          .voltype    = "features/shard",
+          .value      = "off",
+          .op_version = GD_OP_VERSION_3_7_0,
+          .flags      = OPT_FLAG_CLIENT_OPT
+        },
+        { .key        = "features.shard-block-size",
+          .voltype    = "features/shard",
+          .op_version = GD_OP_VERSION_3_7_0,
+          .flags      = OPT_FLAG_CLIENT_OPT
+        },
         { .key         = NULL
         }
 };