dm log: make module use tracking internal

Remove internal module reference fields from the interface.

Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 82df73f67a0d3a70d6b13c15ab961035f98d8687..e6b6a9d5fdd2651aeca88262a211e7aed67e3bea 100644 (file)
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -16,34 +16,51 @@
 
 #define DM_MSG_PREFIX "dirty region log"
 
+struct dm_dirty_log_internal {
+       struct dm_dirty_log_type *type;
+
+       struct list_head list;
+       long use;
+};
+
 static LIST_HEAD(_log_types);
 static DEFINE_SPINLOCK(_lock);
 
-static struct dm_dirty_log_type *_get_type(const char *type_name)
+static struct dm_dirty_log_internal *__find_dirty_log_type(const char *name)
 {
-       struct dm_dirty_log_type *type;
+       struct dm_dirty_log_internal *log_type;
+
+       list_for_each_entry(log_type, &_log_types, list)
+               if (!strcmp(name, log_type->type->name))
+                       return log_type;
+
+       return NULL;
+}
+
+static struct dm_dirty_log_internal *_get_dirty_log_type(const char *name)
+{
+       struct dm_dirty_log_internal *log_type;
 
        spin_lock(&_lock);
-       list_for_each_entry (type, &_log_types, list)
-               if (!strcmp(type_name, type->name)) {
-                       if (!type->use_count && !try_module_get(type->module)){
-                               spin_unlock(&_lock);
-                               return NULL;
-                       }
-                       type->use_count++;
-                       spin_unlock(&_lock);
-                       return type;
-               }
+
+       log_type = __find_dirty_log_type(name);
+       if (log_type) {
+               if (!log_type->use && !try_module_get(log_type->type->module))
+                       log_type = NULL;
+               else
+                       log_type->use++;
+       }
 
        spin_unlock(&_lock);
-       return NULL;
+
+       return log_type;
 }
 
 /*
  * get_type
  * @type_name
  *
- * Attempt to retrieve the dirty_log_type by name.  If not already
+ * Attempt to retrieve the dm_dirty_log_type by name.  If not already
  * available, attempt to load the appropriate module.
  *
  * Log modules are named "dm-log-" followed by the 'type_name'.
@@ -59,11 +76,14 @@ static struct dm_dirty_log_type *_get_type(const char *type_name)
 static struct dm_dirty_log_type *get_type(const char *type_name)
 {
        char *p, *type_name_dup;
-       struct dm_dirty_log_type *type;
+       struct dm_dirty_log_internal *log_type;
 
-       type = _get_type(type_name);
-       if (type)
-               return type;
+       if (!type_name)
+               return NULL;
+
+       log_type = _get_dirty_log_type(type_name);
+       if (log_type)
+               return log_type->type;
 
        type_name_dup = kstrdup(type_name, GFP_KERNEL);
        if (!type_name_dup) {
@@ -73,50 +93,95 @@ static struct dm_dirty_log_type *get_type(const char *type_name)
        }
 
        while (request_module("dm-log-%s", type_name_dup) ||
-              !(type = _get_type(type_name))) {
+              !(log_type = _get_dirty_log_type(type_name))) {
                p = strrchr(type_name_dup, '-');
                if (!p)
                        break;
                p[0] = '\0';
        }
 
-       if (!type)
+       if (!log_type)
                DMWARN("Module for logging type \"%s\" not found.", type_name);
 
        kfree(type_name_dup);
 
-       return type;
+       return log_type ? log_type->type : NULL;
 }
 
 static void put_type(struct dm_dirty_log_type *type)
 {
+       struct dm_dirty_log_internal *log_type;
+
+       if (!type)
+               return;
+
        spin_lock(&_lock);
-       if (!--type->use_count)
+       log_type = __find_dirty_log_type(type->name);
+       if (!log_type)
+               goto out;
+
+       if (!--log_type->use)
                module_put(type->module);
+
+       BUG_ON(log_type->use < 0);
+
+out:
        spin_unlock(&_lock);
 }
 
+static struct dm_dirty_log_internal *_alloc_dirty_log_type(struct dm_dirty_log_type *type)
+{
+       struct dm_dirty_log_internal *log_type = kzalloc(sizeof(*log_type),
+                                                        GFP_KERNEL);
+
+       if (log_type)
+               log_type->type = type;
+
+       return log_type;
+}
+
 int dm_dirty_log_type_register(struct dm_dirty_log_type *type)
 {
+       struct dm_dirty_log_internal *log_type = _alloc_dirty_log_type(type);
+       int r = 0;
+
+       if (!log_type)
+               return -ENOMEM;
+
        spin_lock(&_lock);
-       type->use_count = 0;
-       list_add(&type->list, &_log_types);
+       if (!__find_dirty_log_type(type->name))
+               list_add(&log_type->list, &_log_types);
+       else {
+               kfree(log_type);
+               r = -EEXIST;
+       }
        spin_unlock(&_lock);
 
-       return 0;
+       return r;
 }
 EXPORT_SYMBOL(dm_dirty_log_type_register);
 
 int dm_dirty_log_type_unregister(struct dm_dirty_log_type *type)
 {
+       struct dm_dirty_log_internal *log_type;
+
        spin_lock(&_lock);
 
-       if (type->use_count)
-               DMWARN("Attempt to unregister a log type that is still in use");
-       else
-               list_del(&type->list);
+       log_type = __find_dirty_log_type(type->name);
+       if (!log_type) {
+               spin_unlock(&_lock);
+               return -EINVAL;
+       }
+
+       if (log_type->use) {
+               spin_unlock(&_lock);
+               return -ETXTBSY;
+       }
+
+       list_del(&log_type->list);
 
        spin_unlock(&_lock);
+       kfree(log_type);
 
        return 0;
 }

diff --git a/drivers/md/dm-log.h b/drivers/md/dm-log.h
index 2da48a857cb9e9ce0e54d22ac65dd50e69858cf6..600c5fb2daad4c231b53a4654316469895af9b0c 100644 (file)
--- a/drivers/md/dm-log.h
+++ b/drivers/md/dm-log.h
@@ -25,10 +25,8 @@ struct dm_dirty_log {
 };
 
 struct dm_dirty_log_type {
-       struct list_head list;
        const char *name;
        struct module *module;
-       unsigned use_count;
 
        int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
                   unsigned argc, char **argv);