Fetch backup volfile servers from glusterd2

Clients will request for a list of volfile servers from glusterd2 by
setting a (optional) flag in GETSPEC RPC call. glusterd2 will check for
the presence of this flag and accordingly return a list of glusterd2
servers in GETSPEC RPC reply. Currently, this list of servers returned
only contains servers which have bricks belonging to the volume.

See:
https://github.com/gluster/glusterd2/issues/382
https://github.com/gluster/glusterfs/issues/351

Updates #351
Change-Id: I0eee3d0bf25a87627e562380ef73063926a16b81
Signed-off-by: Prashanth Pai <ppai@redhat.com>

2 files changed, 54 insertions, 31 deletions

diff --git a/glusterfsd/src/glusterfsd-mgmt.c b/glusterfsd/src/glusterfsd-mgmt.c
index 4c4d98dad3e..5d0c83fd1a6 100644
--- a/glusterfsd/src/glusterfsd-mgmt.c
+++ b/glusterfsd/src/glusterfsd-mgmt.c
@@ -1917,6 +1917,8 @@ mgmt_getspec_cbk (struct rpc_req *req, struct iovec *iov, int count,
         gf_volfile_t            *volfile_obj = NULL;
         gf_volfile_t            *volfile_tmp = NULL;
         char                     sha256_hash[SHA256_DIGEST_LENGTH] = {0, };
+        dict_t                  *dict = NULL;
+        char                    *servers_list = NULL;
 
         frame = myframe;
         ctx = frame->this->ctx;
@@ -1940,6 +1942,44 @@ mgmt_getspec_cbk (struct rpc_req *req, struct iovec *iov, int count,
                 goto out;
         }
 
+        if (!rsp.xdata.xdata_len) {
+                goto volfile;
+        }
+
+        dict = dict_new ();
+        if (!dict) {
+                ret = -1;
+                errno = ENOMEM;
+                goto out;
+        }
+
+        ret = dict_unserialize (rsp.xdata.xdata_val, rsp.xdata.xdata_len,
+                                &dict);
+        if (ret) {
+                gf_log (frame->this->name, GF_LOG_ERROR,
+                        "failed to unserialize xdata to dictionary");
+                goto out;
+        }
+        dict->extra_stdfree = rsp.xdata.xdata_val;
+
+        /* glusterd2 only */
+        ret = dict_get_str (dict, "servers-list", &servers_list);
+        if (ret) {
+                goto volfile;
+        }
+
+        gf_log (frame->this->name, GF_LOG_INFO,
+                "Received list of available volfile servers: %s",
+                servers_list);
+
+        ret = gf_process_getspec_servers_list(&ctx->cmd_args, servers_list);
+        if (ret) {
+                gf_log (frame->this->name, GF_LOG_ERROR,
+                        "Failed (%s) to process servers list: %s",
+                        strerror (errno), servers_list);
+        }
+
+volfile:
         ret = 0;
         size = rsp.op_ret;
 
@@ -2058,6 +2098,9 @@ out:
 
         free (rsp.spec);
 
+        if (dict)
+                dict_unref (dict);
+
         // Stop if server is running at an unsupported op-version
         if (ENOTSUP == ret) {
                 gf_log ("mgmt", GF_LOG_ERROR, "Server is operating at an "
@@ -2133,6 +2176,11 @@ glusterfs_volfile_fetch_one (glusterfs_ctx_t *ctx, char *volfile_id)
                 goto out;
         }
 
+        /* Ask for a list of volfile (glusterd2 only) servers */
+        if (GF_CLIENT_PROCESS == ctx->process_mode) {
+                req.flags = req.flags | GF_GETSPEC_FLAG_SERVERS_LIST;
+        }
+
         if (cmd_args->brick_name) {
                 ret = dict_set_dynstr_with_alloc (dict, "brick_name",
                                                   cmd_args->brick_name);
diff --git a/glusterfsd/src/glusterfsd.c b/glusterfsd/src/glusterfsd.c
index 3bfd0f12384..dfaf9c09c6d 100644
--- a/glusterfsd/src/glusterfsd.c
+++ b/glusterfsd/src/glusterfsd.c
@@ -718,7 +718,6 @@ gf_remember_backup_volfile_server (char *arg)
         glusterfs_ctx_t         *ctx = NULL;
         cmd_args_t              *cmd_args = NULL;
         int                      ret = -1;
-        server_cmdline_t        *server = NULL;
 
         ctx = glusterfsd_ctx;
         if (!ctx)
@@ -728,39 +727,15 @@ gf_remember_backup_volfile_server (char *arg)
         if(!cmd_args)
                 goto out;
 
-        server = GF_CALLOC (1, sizeof (server_cmdline_t),
-                            gfd_mt_server_cmdline_t);
-        if (!server)
-                goto out;
-
-        INIT_LIST_HEAD(&server->list);
-
-        server->volfile_server = gf_strdup(arg);
-
-        if (!cmd_args->volfile_server) {
-                cmd_args->volfile_server = server->volfile_server;
-                cmd_args->curr_server = server;
-        }
-
-        if (!server->volfile_server) {
-                gf_msg ("glusterfsd", GF_LOG_WARNING, 0, glusterfsd_msg_10,
-                        "xlator option %s is invalid", arg);
-                goto out;
+        ret = gf_set_volfile_server_common(cmd_args, arg,
+                                           GF_DEFAULT_VOLFILE_TRANSPORT,
+                                           GF_DEFAULT_BASE_PORT);
+        if (ret) {
+                gf_log ("glusterfs", GF_LOG_ERROR,
+                        "failed to set volfile server: %s", strerror (errno));
         }
-
-        list_add_tail (&server->list, &cmd_args->volfile_servers);
-
-        ret = 0;
 out:
-        if (ret == -1) {
-                if (server) {
-                        GF_FREE (server->volfile_server);
-                        GF_FREE (server);
-                }
-        }
-
         return ret;
-
 }
 
 static int