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, 72 insertions, 52 deletions

diff --git a/api/src/glfs-mgmt.c b/api/src/glfs-mgmt.c
index ac306e40027..f709b54d49e 100644
--- a/api/src/glfs-mgmt.c
+++ b/api/src/glfs-mgmt.c
@@ -580,6 +580,8 @@ glfs_mgmt_getspec_cbk (struct rpc_req *req, struct iovec *iov, int count,
 	FILE			*tmpfp = NULL;
 	int			 need_retry = 0;
 	struct glfs		*fs = NULL;
+        dict_t                  *dict = NULL;
+        char                    *servers_list = NULL;
 
 	frame = myframe;
 	ctx = frame->this->ctx;
@@ -617,6 +619,44 @@ glfs_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;
 
@@ -676,8 +716,8 @@ out:
 	if (rsp.spec)
 		free (rsp.spec);
 
-        if (rsp.xdata.xdata_val)
-                free (rsp.xdata.xdata_val);
+        if (dict)
+                dict_unref (dict);
 
 	// Stop if server is running at an unsupported op-version
 	if (ENOTSUP == ret) {
@@ -752,6 +792,11 @@ glfs_volfile_fetch (struct glfs *fs)
                 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;
+        }
+
         ret = dict_allocate_and_serialize (dict, &req.xdata.xdata_val,
                                            &req.xdata.xdata_len);
         if (ret < 0) {
diff --git a/api/src/glfs.c b/api/src/glfs.c
index 2a7ae2f3986..6724534fb31 100644
--- a/api/src/glfs.c
+++ b/api/src/glfs.c
@@ -412,9 +412,9 @@ pub_glfs_set_volfile_server (struct glfs *fs, const char *transport,
                              const char *host, int port)
 {
         cmd_args_t            *cmd_args = NULL;
-        server_cmdline_t      *server = NULL;
-        server_cmdline_t      *tmp = NULL;
         int                    ret = -1;
+        char                  *server_host = NULL;
+        char                  *server_transport = NULL;
 
         if (!fs || !host) {
                 errno = EINVAL;
@@ -425,21 +425,10 @@ pub_glfs_set_volfile_server (struct glfs *fs, const char *transport,
         __GLFS_ENTRY_VALIDATE_FS (fs, invalid_fs);
 
         cmd_args = &fs->ctx->cmd_args;
-
         cmd_args->max_connect_attempts = 1;
 
-        server = GF_CALLOC (1, sizeof (server_cmdline_t),
-                            glfs_mt_server_cmdline_t);
-
-        if (!server) {
-                errno = ENOMEM;
-                goto out;
-        }
-
-        INIT_LIST_HEAD (&server->list);
-
-        server->volfile_server = gf_strdup (host);
-        if (!server->volfile_server) {
+        server_host = gf_strdup (host);
+        if (!server_host) {
                 errno = ENOMEM;
                 goto out;
         }
@@ -447,9 +436,10 @@ pub_glfs_set_volfile_server (struct glfs *fs, const char *transport,
         if (transport) {
                 /* volfile fetch support over tcp|unix only */
                 if (!strcmp(transport, "tcp") || !strcmp(transport, "unix")) {
-                        server->transport = gf_strdup (transport);
+                        server_transport = gf_strdup (transport);
                 } else if (!strcmp(transport, "rdma")) {
-                        server->transport = gf_strdup ("tcp");
+                        server_transport =
+                                gf_strdup (GF_DEFAULT_VOLFILE_TRANSPORT);
                         gf_msg ("glfs", GF_LOG_WARNING, EINVAL,
                                 API_MSG_INVALID_ENTRY,
                                 "transport RDMA is deprecated, "
@@ -460,55 +450,39 @@ pub_glfs_set_volfile_server (struct glfs *fs, const char *transport,
                                 "transport %s is not supported, "
                                 "possible values tcp|unix",
                                 transport);
-                        ret = -1;
                         goto out;
                 }
         } else {
-                server->transport = gf_strdup (GF_DEFAULT_VOLFILE_TRANSPORT);
+                server_transport = gf_strdup (GF_DEFAULT_VOLFILE_TRANSPORT);
         }
 
-        if (!server->transport) {
+        if (!server_transport) {
                 errno = ENOMEM;
                 goto out;
         }
 
-        if (strcmp(server->transport, "unix")) {
-                if (port) {
-                        server->port = port;
-                } else {
-                        server->port = GF_DEFAULT_BASE_PORT;
-                }
-        } else {
-                server->port = 0;
+        if (!port) {
+                port = GF_DEFAULT_BASE_PORT;
         }
 
-        if (!cmd_args->volfile_server) {
-                cmd_args->volfile_server = server->volfile_server;
-                cmd_args->volfile_server_transport = server->transport;
-                cmd_args->volfile_server_port = server->port;
-                cmd_args->curr_server = server;
+        if (!strcmp(server_transport, "unix")) {
+                port = 0;
         }
 
-        list_for_each_entry(tmp, &cmd_args->volfile_servers, list) {
-                if ((!strcmp(tmp->volfile_server, server->volfile_server) &&
-                     !strcmp(tmp->transport, server->transport) &&
-                     (tmp->port == server->port))) {
-                        errno = EEXIST;
-                        ret = -1;
-                        goto out;
-                }
+        ret = gf_set_volfile_server_common(cmd_args, server_host,
+                                           server_transport, port);
+        if (ret) {
+                gf_log ("glfs", 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->transport);
-                        GF_FREE (server);
-                }
+        if (server_host) {
+                GF_FREE (server_host);
+        }
+
+        if (server_transport) {
+                GF_FREE (server_transport);
         }
 
         __GLFS_EXIT_FS;
@@ -823,6 +797,7 @@ pub_glfs_new (const char *volname)
                 goto out;
 
         fs->ctx = ctx;
+        fs->ctx->process_mode = GF_CLIENT_PROCESS;
 
         ret = glfs_set_logging (fs, "/dev/null", 0);
         if (ret)