ocfs2: Create stack glue sysfs files.

Introduce a set of sysfs files that describe the current stack glue
state.  The files live under /sys/fs/ocfs2.  The locking_protocol file
displays the version of ocfs2's locking code.  The
loaded_cluster_plugins file displays all of the currently loaded stack
plugins.  When filesystems are mounted, the active_cluster_plugin file
will display the plugin in use.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 120 insertions, 1 deletions

diff --git a/fs/ocfs2/stackglue.c b/fs/ocfs2/stackglue.c
index 1978c9cff0e9..76ae4fcebcbd 100644
--- a/fs/ocfs2/stackglue.c
+++ b/fs/ocfs2/stackglue.c
@@ -23,6 +23,9 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/kmod.h>
+#include <linux/fs.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
 
 #include "stackglue.h"
 
@@ -335,14 +338,130 @@ int ocfs2_cluster_this_node(unsigned int *node)
 EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
 
 
-static int __init ocfs2_stack_glue_init(void)
+/*
+ * Sysfs bits
+ */
+
+static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
+                                               struct kobj_attribute *attr,
+                                               char *buf)
+{
+        ssize_t ret = 0;
+
+        spin_lock(&ocfs2_stack_lock);
+        if (lproto)
+                ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
+                               lproto->lp_max_version.pv_major,
+                               lproto->lp_max_version.pv_minor);
+        spin_unlock(&ocfs2_stack_lock);
+
+        return ret;
+}
+
+static struct kobj_attribute ocfs2_attr_max_locking_protocol =
+        __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
+               ocfs2_max_locking_protocol_show, NULL);
+
+static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
+                                                 struct kobj_attribute *attr,
+                                                 char *buf)
 {
+        ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
+        struct ocfs2_stack_plugin *p;
+
+        spin_lock(&ocfs2_stack_lock);
+        list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
+                ret = snprintf(buf, remain, "%s\n",
+                               p->sp_name);
+                if (ret < 0) {
+                        total = ret;
+                        break;
+                }
+                if (ret == remain) {
+                        /* snprintf() didn't fit */
+                        total = -E2BIG;
+                        break;
+                }
+                total += ret;
+                remain -= ret;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+
+        return total;
+}
+
+static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
+        __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
+               ocfs2_loaded_cluster_plugins_show, NULL);
+
+static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
+                                                struct kobj_attribute *attr,
+                                                char *buf)
+{
+        ssize_t ret = 0;
+
+        spin_lock(&ocfs2_stack_lock);
+        if (active_stack) {
+                ret = snprintf(buf, PAGE_SIZE, "%s\n",
+                               active_stack->sp_name);
+                if (ret == PAGE_SIZE)
+                        ret = -E2BIG;
+        }
+        spin_unlock(&ocfs2_stack_lock);
+
+        return ret;
+}
+
+static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
+        __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
+               ocfs2_active_cluster_plugin_show, NULL);
+
+static struct attribute *ocfs2_attrs[] = {
+        &ocfs2_attr_max_locking_protocol.attr,
+        &ocfs2_attr_loaded_cluster_plugins.attr,
+        &ocfs2_attr_active_cluster_plugin.attr,
+        NULL,
+};
+
+static struct attribute_group ocfs2_attr_group = {
+        .attrs = ocfs2_attrs,
+};
+
+static struct kset *ocfs2_kset;
+
+static void ocfs2_sysfs_exit(void)
+{
+        kset_unregister(ocfs2_kset);
+}
+
+static int ocfs2_sysfs_init(void)
+{
+        int ret;
+
+        ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
+        if (!ocfs2_kset)
+                return -ENOMEM;
+
+        ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
+        if (ret)
+                goto error;
+
         return 0;
+
+error:
+        kset_unregister(ocfs2_kset);
+        return ret;
+}
+
+static int __init ocfs2_stack_glue_init(void)
+{
+        return ocfs2_sysfs_init();
 }
 
 static void __exit ocfs2_stack_glue_exit(void)
 {
         lproto = NULL;
+        ocfs2_sysfs_exit();
 }
 
 MODULE_AUTHOR("Oracle");