meta: (re-)Implement Meta translator

The meta translator exposes details about glusterfs itself
in the form of a virtual namespace.

Loading the translator on the client side creates the
meta virtual view under $mntpoint/.meta by default. The
directory is not listed (even with ls -a) and can be
accessed by doing a "cd /mnt/.meta"

Change-Id: I5ffdf39203841a9562a8280a1f79dc76d4dded5d
BUG: 1089216
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/7509
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Harshavardhana <harsha@harshavardhana.net>

1 files changed, 106 insertions, 0 deletions

diff --git a/xlators/meta/src/plugins/graph-dir.c b/xlators/meta/src/plugins/graph-dir.c
new file mode 100644
index 00000000000..3cd6b482e74
--- /dev/null
+++ b/xlators/meta/src/plugins/graph-dir.c
@@ -0,0 +1,106 @@
+/*
+   Copyright (c) 2014 Red Hat, Inc. <http://www.redhat.com>
+   This file is part of GlusterFS.
+
+   This file is licensed to you under your choice of the GNU Lesser
+   General Public License, version 3 or any later version (LGPLv3 or
+   later), or the GNU General Public License, version 2 (GPLv2), in all
+   cases as published by the Free Software Foundation.
+*/
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "xlator.h"
+#include "defaults.h"
+
+#include "meta-mem-types.h"
+#include "meta.h"
+#include "meta-hooks.h"
+
+
+static struct meta_dirent graph_dir_dirents[] = {
+	DOT_DOTDOT,
+
+	{ .name = "top",
+	  .type = IA_IFLNK,
+	  .hook = meta_top_link_hook,
+	},
+	{ .name = "volfile",
+	  .type = IA_IFREG,
+	  .hook = meta_volfile_file_hook,
+	},
+	{ .name = NULL }
+};
+
+
+static int
+graph_dir_fill (xlator_t *this, inode_t *inode, struct meta_dirent **dp)
+{
+	struct meta_dirent *dirents = NULL;
+	glusterfs_graph_t *graph = NULL;
+	int i = 0;
+	int count = 0;
+	xlator_t *xl = NULL;
+
+	graph = meta_ctx_get (inode, this);
+
+	for (xl = graph->first; xl; xl = xl->next)
+		count++;
+
+	dirents = GF_CALLOC (sizeof (*dirents), count, gf_meta_mt_dirents_t);
+	if (!dirents)
+		return -1;
+
+	i = 0;
+	for (xl = graph->first; xl; xl = xl->next) {
+		dirents[i].name = gf_strdup (xl->name);
+		dirents[i].type = IA_IFDIR;
+		dirents[i].hook = meta_xlator_dir_hook;
+		i++;
+	}
+
+	*dp = dirents;
+	return i;
+}
+
+
+struct meta_ops graph_dir_ops = {
+	.fixed_dirents = graph_dir_dirents,
+	.dir_fill = graph_dir_fill,
+};
+
+
+static glusterfs_graph_t *
+glusterfs_graph_lookup (xlator_t *this, const char *graph_uuid)
+{
+	glusterfs_graph_t *graph = NULL;
+	glusterfs_graph_t *tmp = NULL;
+
+	list_for_each_entry (tmp, &this->ctx->graphs, list) {
+		if (strcmp (graph_uuid, tmp->graph_uuid) == 0) {
+			graph = tmp;
+			break;
+		}
+	}
+
+	return graph;
+}
+
+
+int
+meta_graph_dir_hook (call_frame_t *frame, xlator_t *this, loc_t *loc,
+		     dict_t *xdata)
+{
+	glusterfs_graph_t *graph = NULL;
+
+	graph = glusterfs_graph_lookup (this, loc->name);
+
+	meta_ops_set (loc->inode, this, &graph_dir_ops);
+
+	meta_ctx_set (loc->inode, this, (void *) graph);
+
+	return 0;
+}