ocfs2/cluster: Add new function o2net_fill_node_map()

Patch adds function o2net_fill_node_map() to return the bitmap of nodes that
it is connected to. This bitmap is also accessible by the user via the debugfs
file, /sys/kernel/debug/o2net/connected_nodes.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>

3 files changed, 90 insertions, 33 deletions

diff --git a/fs/ocfs2/cluster/netdebug.c b/fs/ocfs2/cluster/netdebug.c
index 3a5835904b3d..dc45deb19e68 100644
--- a/fs/ocfs2/cluster/netdebug.c
+++ b/fs/ocfs2/cluster/netdebug.c
@@ -47,6 +47,7 @@
 #define SC_DEBUG_NAME           "sock_containers"
 #define NST_DEBUG_NAME          "send_tracking"
 #define STATS_DEBUG_NAME        "stats"
+#define NODES_DEBUG_NAME        "connected_nodes"
 
 #define SHOW_SOCK_CONTAINERS    0
 #define SHOW_SOCK_STATS         1
@@ -55,6 +56,7 @@ static struct dentry *o2net_dentry;
 static struct dentry *sc_dentry;
 static struct dentry *nst_dentry;
 static struct dentry *stats_dentry;
+static struct dentry *nodes_dentry;
 
 static DEFINE_SPINLOCK(o2net_debug_lock);
 
@@ -491,53 +493,87 @@ static const struct file_operations sc_seq_fops = {
         .release = sc_fop_release,
 };
 
-int o2net_debugfs_init(void)
+static int o2net_fill_bitmap(char *buf, int len)
 {
-        o2net_dentry = debugfs_create_dir(O2NET_DEBUG_DIR, NULL);
-        if (!o2net_dentry) {
-                mlog_errno(-ENOMEM);
-                goto bail;
-        }
+        unsigned long map[BITS_TO_LONGS(O2NM_MAX_NODES)];
+        int i = -1, out = 0;
 
-        nst_dentry = debugfs_create_file(NST_DEBUG_NAME, S_IFREG|S_IRUSR,
-                                         o2net_dentry, NULL,
-                                         &nst_seq_fops);
-        if (!nst_dentry) {
-                mlog_errno(-ENOMEM);
-                goto bail;
-        }
+        o2net_fill_node_map(map, sizeof(map));
 
-        sc_dentry = debugfs_create_file(SC_DEBUG_NAME, S_IFREG|S_IRUSR,
-                                        o2net_dentry, NULL,
-                                        &sc_seq_fops);
-        if (!sc_dentry) {
-                mlog_errno(-ENOMEM);
-                goto bail;
-        }
+        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");
 
-        stats_dentry = debugfs_create_file(STATS_DEBUG_NAME, S_IFREG|S_IRUSR,
-                                           o2net_dentry, NULL,
-                                           &stats_seq_fops);
-        if (!stats_dentry) {
-                mlog_errno(-ENOMEM);
-                goto bail;
-        }
+        return out;
+}
+
+static int nodes_fop_open(struct inode *inode, struct file *file)
+{
+        char *buf;
+
+        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+        if (!buf)
+                return -ENOMEM;
+
+        i_size_write(inode, o2net_fill_bitmap(buf, PAGE_SIZE));
+
+        file->private_data = buf;
 
         return 0;
-bail:
-        debugfs_remove(stats_dentry);
-        debugfs_remove(sc_dentry);
-        debugfs_remove(nst_dentry);
-        debugfs_remove(o2net_dentry);
-        return -ENOMEM;
 }
 
+static int o2net_debug_release(struct inode *inode, struct file *file)
+{
+        kfree(file->private_data);
+        return 0;
+}
+
+static ssize_t o2net_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));
+}
+
+static const struct file_operations nodes_fops = {
+        .open           = nodes_fop_open,
+        .release        = o2net_debug_release,
+        .read           = o2net_debug_read,
+        .llseek         = generic_file_llseek,
+};
+
 void o2net_debugfs_exit(void)
 {
+        debugfs_remove(nodes_dentry);
         debugfs_remove(stats_dentry);
         debugfs_remove(sc_dentry);
         debugfs_remove(nst_dentry);
         debugfs_remove(o2net_dentry);
 }
 
+int o2net_debugfs_init(void)
+{
+        mode_t mode = S_IFREG|S_IRUSR;
+
+        o2net_dentry = debugfs_create_dir(O2NET_DEBUG_DIR, NULL);
+        if (o2net_dentry)
+                nst_dentry = debugfs_create_file(NST_DEBUG_NAME, mode,
+                                        o2net_dentry, NULL, &nst_seq_fops);
+        if (nst_dentry)
+                sc_dentry = debugfs_create_file(SC_DEBUG_NAME, mode,
+                                        o2net_dentry, NULL, &sc_seq_fops);
+        if (sc_dentry)
+                stats_dentry = debugfs_create_file(STATS_DEBUG_NAME, mode,
+                                        o2net_dentry, NULL, &stats_seq_fops);
+        if (stats_dentry)
+                nodes_dentry = debugfs_create_file(NODES_DEBUG_NAME, mode,
+                                        o2net_dentry, NULL, &nodes_fops);
+        if (nodes_dentry)
+                return 0;
+
+        o2net_debugfs_exit();
+        mlog_errno(-ENOMEM);
+        return -ENOMEM;
+}
+
 #endif  /* CONFIG_DEBUG_FS */
diff --git a/fs/ocfs2/cluster/tcp.c b/fs/ocfs2/cluster/tcp.c
index 6e97895ecf24..ae13d5ca7908 100644
--- a/fs/ocfs2/cluster/tcp.c
+++ b/fs/ocfs2/cluster/tcp.c
@@ -1034,6 +1034,25 @@ static int o2net_tx_can_proceed(struct o2net_node *nn,
         return ret;
 }
 
+/* Get a map of all nodes to which this node is currently connected to */
+void o2net_fill_node_map(unsigned long *map, unsigned bytes)
+{
+        struct o2net_sock_container *sc;
+        int node, ret;
+
+        BUG_ON(bytes < (BITS_TO_LONGS(O2NM_MAX_NODES) * sizeof(unsigned long)));
+
+        memset(map, 0, bytes);
+        for (node = 0; node < O2NM_MAX_NODES; ++node) {
+                o2net_tx_can_proceed(o2net_nn_from_num(node), &sc, &ret);
+                if (!ret) {
+                        set_bit(node, map);
+                        sc_put(sc);
+                }
+        }
+}
+EXPORT_SYMBOL_GPL(o2net_fill_node_map);
+
 int o2net_send_message_vec(u32 msg_type, u32 key, struct kvec *caller_vec,
                            size_t caller_veclen, u8 target_node, int *status)
 {
diff --git a/fs/ocfs2/cluster/tcp.h b/fs/ocfs2/cluster/tcp.h
index fd6179eb26d4..5bada2a69b50 100644
--- a/fs/ocfs2/cluster/tcp.h
+++ b/fs/ocfs2/cluster/tcp.h
@@ -106,6 +106,8 @@ int o2net_register_handler(u32 msg_type, u32 key, u32 max_len,
                            struct list_head *unreg_list);
 void o2net_unregister_handler_list(struct list_head *list);
 
+void o2net_fill_node_map(unsigned long *map, unsigned bytes);
+
 struct o2nm_node;
 int o2net_register_hb_callbacks(void);
 void o2net_unregister_hb_callbacks(void);