ceph: additional debugfs output

MDS session state and client global ID is
useful instrumentation when testing.
Signed-off-by: John Spray <john.spray@redhat.com>

fs/ceph/debugfs.c

@@ -158,10 +158,47 @@ static int dentry_lru_show(struct seq_file *s, void *ptr)
 	return 0;
 }
 
+static int mds_sessions_show(struct seq_file *s, void *ptr)
+{
+	struct ceph_fs_client *fsc = s->private;
+	struct ceph_mds_client *mdsc = fsc->mdsc;
+	struct ceph_auth_client *ac = fsc->client->monc.auth;
+	struct ceph_options *opt = fsc->client->options;
+	int mds = -1;
+
+	mutex_lock(&mdsc->mutex);
+
+	/* The 'num' portion of an 'entity name' */
+	seq_printf(s, "global_id %llu\n", ac->global_id);
+
+	/* The -o name mount argument */
+	seq_printf(s, "name \"%s\"\n", opt->name ? opt->name : "");
+
+	/* The list of MDS session rank+state */
+	for (mds = 0; mds < mdsc->max_sessions; mds++) {
+		struct ceph_mds_session *session =
+			__ceph_lookup_mds_session(mdsc, mds);
+		if (!session) {
+			continue;
+		}
+		mutex_unlock(&mdsc->mutex);
+		seq_printf(s, "mds.%d %s\n",
+				session->s_mds,
+				ceph_session_state_name(session->s_state));
+
+		ceph_put_mds_session(session);
+		mutex_lock(&mdsc->mutex);
+	}
+	mutex_unlock(&mdsc->mutex);
+
+	return 0;
+}
+
 CEPH_DEFINE_SHOW_FUNC(mdsmap_show)
 CEPH_DEFINE_SHOW_FUNC(mdsc_show)
 CEPH_DEFINE_SHOW_FUNC(caps_show)
 CEPH_DEFINE_SHOW_FUNC(dentry_lru_show)
+CEPH_DEFINE_SHOW_FUNC(mds_sessions_show)
 
 
 /*
@@ -193,6 +230,7 @@ void ceph_fs_debugfs_cleanup(struct ceph_fs_client *fsc)
 	debugfs_remove(fsc->debugfs_bdi);
 	debugfs_remove(fsc->debugfs_congestion_kb);
 	debugfs_remove(fsc->debugfs_mdsmap);
+	debugfs_remove(fsc->debugfs_mds_sessions);
 	debugfs_remove(fsc->debugfs_caps);
 	debugfs_remove(fsc->debugfs_mdsc);
 	debugfs_remove(fsc->debugfs_dentry_lru);
@@ -231,6 +269,14 @@ int ceph_fs_debugfs_init(struct ceph_fs_client *fsc)
 	if (!fsc->debugfs_mdsmap)
 		goto out;
 
+	fsc->debugfs_mds_sessions = debugfs_create_file("mds_sessions",
+					0600,
+					fsc->client->debugfs_dir,
+					fsc,
+					&mds_sessions_show_fops);
+	if (!fsc->debugfs_mds_sessions)
+		goto out;
+
 	fsc->debugfs_mdsc = debugfs_create_file("mdsc",
 						0600,
 						fsc->client->debugfs_dir,

fs/ceph/super.h

@@ -95,6 +95,7 @@ struct ceph_fs_client {
 	struct dentry *debugfs_congestion_kb;
 	struct dentry *debugfs_bdi;
 	struct dentry *debugfs_mdsc, *debugfs_mdsmap;
+	struct dentry *debugfs_mds_sessions;
 #endif
 
 #ifdef CONFIG_CEPH_FSCACHE