[dm-devel] [PATCH 2/2] dm log: remove struct dm_dirty_log_internal

[Mike Snitzer]

Remove the 'dm_dirty_log_internal' structure.  The resulting cleanup
eliminates extra memory allocations.  Therefore exposing the internal
list_head to the external 'dm_dirty_log_type' structure is a worthwhile
compromise.

Signed-off-by: Mike Snitzer <snitzer at redhat.com>
---
 drivers/md/dm-log.c          |   60 ++++++++++-------------------------------
 include/linux/dm-dirty-log.h |    3 ++
 2 files changed, 18 insertions(+), 45 deletions(-)

diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 094c8f0..f5e5e11 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -16,34 +16,28 @@
 
 #define DM_MSG_PREFIX "dirty region log"
 
-struct dm_dirty_log_internal {
-	struct dm_dirty_log_type *type;
-
-	struct list_head list;
-};
-
 static LIST_HEAD(_log_types);
 static DEFINE_SPINLOCK(_lock);
 
-static struct dm_dirty_log_internal *__find_dirty_log_type(const char *name)
+static struct dm_dirty_log_type *__find_dirty_log_type(const char *name)
 {
-	struct dm_dirty_log_internal *log_type;
+	struct dm_dirty_log_type *log_type;
 
 	list_for_each_entry(log_type, &_log_types, list)
-		if (!strcmp(name, log_type->type->name))
+		if (!strcmp(name, log_type->name))
 			return log_type;
 
 	return NULL;
 }
 
-static struct dm_dirty_log_internal *_get_dirty_log_type(const char *name)
+static struct dm_dirty_log_type *_get_dirty_log_type(const char *name)
 {
-	struct dm_dirty_log_internal *log_type;
+	struct dm_dirty_log_type *log_type;
 
 	spin_lock(&_lock);
 
 	log_type = __find_dirty_log_type(name);
-	if (log_type && !try_module_get(log_type->type->module))
+	if (log_type && !try_module_get(log_type->module))
 		log_type = NULL;
 
 	spin_unlock(&_lock);
@@ -71,14 +65,14 @@ static struct dm_dirty_log_internal *_get_dirty_log_type(const char *name)
 static struct dm_dirty_log_type *get_type(const char *type_name)
 {
 	char *p, *type_name_dup;
-	struct dm_dirty_log_internal *log_type;
+	struct dm_dirty_log_type *log_type;
 
 	if (!type_name)
 		return NULL;
 
 	log_type = _get_dirty_log_type(type_name);
 	if (log_type)
-		return log_type->type;
+		return log_type;
 
 	type_name_dup = kstrdup(type_name, GFP_KERNEL);
 	if (!type_name_dup) {
@@ -100,19 +94,16 @@ static struct dm_dirty_log_type *get_type(const char *type_name)
 
 	kfree(type_name_dup);
 
-	return log_type ? log_type->type : NULL;
+	return log_type;
 }
 
 static void put_type(struct dm_dirty_log_type *type)
 {
-	struct dm_dirty_log_internal *log_type;
-
 	if (!type)
 		return;
 
-	spin_lock(&_lock);
-	log_type = __find_dirty_log_type(type->name);
-	if (!log_type)
+	spin_lock(&_lock);
+	if (!__find_dirty_log_type(type->name))
 		goto out;
 
 	module_put(type->module);
@@ -121,32 +112,15 @@ 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);
 	if (!__find_dirty_log_type(type->name))
-		list_add(&log_type->list, &_log_types);
-	else {
-		kfree(log_type);
+		list_add(&type->list, &_log_types);
+	else
 		r = -EEXIST;
-	}
 	spin_unlock(&_lock);
 
 	return r;
@@ -155,20 +129,16 @@ 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);
 
-	log_type = __find_dirty_log_type(type->name);
-	if (!log_type) {
+	if (!__find_dirty_log_type(type->name)) {
 		spin_unlock(&_lock);
 		return -EINVAL;
 	}
 
-	list_del(&log_type->list);
+	list_del(&type->list);
 
 	spin_unlock(&_lock);
-	kfree(log_type);
 
 	return 0;
 }
diff --git a/include/linux/dm-dirty-log.h b/include/linux/dm-dirty-log.h
index a6600a5..5e8b11d 100644
--- a/include/linux/dm-dirty-log.h
+++ b/include/linux/dm-dirty-log.h
@@ -28,6 +28,9 @@ struct dm_dirty_log_type {
 	const char *name;
 	struct module *module;
 
+	/* For internal device-mapper use */
+	struct list_head list;
+
 	int (*ctr)(struct dm_dirty_log *log, struct dm_target *ti,
 		   unsigned argc, char **argv);
 	void (*dtr)(struct dm_dirty_log *log);
-- 
1.6.0.6