ocfs2/hb: Expose the list of heartbeating nodes via debugfs

This patch creates a debugfs file, o2hb/livesnodes, which exposes the
aggregate list of heartbeating node across all heartbeat regions.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

3 files changed, 104 insertions, 4 deletions

diff --git a/fs/ocfs2/cluster/heartbeat.c b/fs/ocfs2/cluster/heartbeat.c
index 04697ba7f73e..4f85eceab376 100644
--- a/fs/ocfs2/cluster/heartbeat.c
+++ b/fs/ocfs2/cluster/heartbeat.c
@@ -33,6 +33,7 @@
 #include <linux/random.h>
 #include <linux/crc32.h>
 #include <linux/time.h>
+#include <linux/debugfs.h>
 
 #include "heartbeat.h"
 #include "tcp.h"
@@ -60,6 +61,11 @@ static unsigned long o2hb_live_node_bitmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
 static LIST_HEAD(o2hb_node_events);
 static DECLARE_WAIT_QUEUE_HEAD(o2hb_steady_queue);
 
+#define O2HB_DEBUG_DIR                  "o2hb"
+#define O2HB_DEBUG_LIVENODES            "livenodes"
+static struct dentry *o2hb_debug_dir;
+static struct dentry *o2hb_debug_livenodes;
+
 static LIST_HEAD(o2hb_all_regions);
 
 static struct o2hb_callback {
@@ -905,7 +911,77 @@ static int o2hb_thread(void *data)
         return 0;
 }
 
-void o2hb_init(void)
+#ifdef CONFIG_DEBUG_FS
+static int o2hb_debug_open(struct inode *inode, struct file *file)
+{
+        unsigned long map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        char *buf = NULL;
+        int i = -1;
+        int out = 0;
+
+        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (!buf)
+                goto bail;
+
+        o2hb_fill_node_map(map, sizeof(map));
+
+        while ((i = find_next_bit(map, O2NM_MAX_NODES, i + 1)) < O2NM_MAX_NODES)
+                out += snprintf(buf + out, PAGE_SIZE - out, "%d ", i);
+        out += snprintf(buf + out, PAGE_SIZE - out, "\n");
+
+        i_size_write(inode, out);
+
+        file->private_data = buf;
+
+        return 0;
+bail:
+        return -ENOMEM;
+}
+
+static int o2hb_debug_release(struct inode *inode, struct file *file)
+{
+        kfree(file->private_data);
+        return 0;
+}
+
+static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
+                                 size_t nbytes, loff_t *ppos)
+{
+        return simple_read_from_buffer(buf, nbytes, ppos, file->private_data,
+                                       i_size_read(file->f_mapping->host));
+}
+#else
+static int o2hb_debug_open(struct inode *inode, struct file *file)
+{
+        return 0;
+}
+static int o2hb_debug_release(struct inode *inode, struct file *file)
+{
+        return 0;
+}
+static ssize_t o2hb_debug_read(struct file *file, char __user *buf,
+                               size_t nbytes, loff_t *ppos)
+{
+        return 0;
+}
+#endif  /* CONFIG_DEBUG_FS */
+
+static struct file_operations o2hb_debug_fops = {
+        .open =         o2hb_debug_open,
+        .release =      o2hb_debug_release,
+        .read =         o2hb_debug_read,
+        .llseek =       generic_file_llseek,
+};
+
+void o2hb_exit(void)
+{
+        if (o2hb_debug_livenodes)
+                debugfs_remove(o2hb_debug_livenodes);
+        if (o2hb_debug_dir)
+                debugfs_remove(o2hb_debug_dir);
+}
+
+int o2hb_init(void)
 {
         int i;
 
@@ -918,6 +994,24 @@ void o2hb_init(void)
         INIT_LIST_HEAD(&o2hb_node_events);
 
         memset(o2hb_live_node_bitmap, 0, sizeof(o2hb_live_node_bitmap));
+
+        o2hb_debug_dir = debugfs_create_dir(O2HB_DEBUG_DIR, NULL);
+        if (!o2hb_debug_dir) {
+                mlog_errno(-ENOMEM);
+                return -ENOMEM;
+        }
+
+        o2hb_debug_livenodes = debugfs_create_file(O2HB_DEBUG_LIVENODES,
+                                                   S_IFREG|S_IRUSR,
+                                                   o2hb_debug_dir, NULL,
+                                                   &o2hb_debug_fops);
+        if (!o2hb_debug_livenodes) {
+                mlog_errno(-ENOMEM);
+                debugfs_remove(o2hb_debug_dir);
+                return -ENOMEM;
+        }
+
+        return 0;
 }
 
 /* if we're already in a callback then we're already serialized by the sem */
diff --git a/fs/ocfs2/cluster/heartbeat.h b/fs/ocfs2/cluster/heartbeat.h
index e511339886b3..2f1649253b49 100644
--- a/fs/ocfs2/cluster/heartbeat.h
+++ b/fs/ocfs2/cluster/heartbeat.h
@@ -75,7 +75,8 @@ void o2hb_unregister_callback(const char *region_uuid,
                               struct o2hb_callback_func *hc);
 void o2hb_fill_node_map(unsigned long *map,
                         unsigned bytes);
-void o2hb_init(void);
+void o2hb_exit(void);
+int o2hb_init(void);
 int o2hb_check_node_heartbeating(u8 node_num);
 int o2hb_check_node_heartbeating_from_callback(u8 node_num);
 int o2hb_check_local_node_heartbeating(void);
diff --git a/fs/ocfs2/cluster/nodemanager.c b/fs/ocfs2/cluster/nodemanager.c
index 70e8fa9e2539..7ee6188bc79a 100644
--- a/fs/ocfs2/cluster/nodemanager.c
+++ b/fs/ocfs2/cluster/nodemanager.c
@@ -881,6 +881,7 @@ static void __exit exit_o2nm(void)
         o2cb_sys_shutdown();
 
         o2net_exit();
+        o2hb_exit();
 }
 
 static int __init init_o2nm(void)
@@ -889,11 +890,13 @@ static int __init init_o2nm(void)
 
         cluster_print_version();
 
-        o2hb_init();
+        ret = o2hb_init();
+        if (ret)
+                goto out;
 
         ret = o2net_init();
         if (ret)
-                goto out;
+                goto out_o2hb;
 
         ret = o2net_register_hb_callbacks();
         if (ret)
@@ -916,6 +919,8 @@ out_callbacks:
         o2net_unregister_hb_callbacks();
 out_o2net:
         o2net_exit();
+out_o2hb:
+        o2hb_exit();
 out:
         return ret;
 }