1 files changed, 161 insertions, 0 deletions

diff --git a/drivers/md/dm-cache-policy.c b/drivers/md/dm-cache-policy.c
new file mode 100644
index 000000000000..2cbf5fdaac52
--- /dev/null
+++ b/drivers/md/dm-cache-policy.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2012 Red Hat. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-cache-policy-internal.h"
+#include "dm.h"
+
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*----------------------------------------------------------------*/
+
+#define DM_MSG_PREFIX "cache-policy"
+
+static DEFINE_SPINLOCK(register_lock);
+static LIST_HEAD(register_list);
+
+static struct dm_cache_policy_type *__find_policy(const char *name)
+{
+        struct dm_cache_policy_type *t;
+
+        list_for_each_entry(t, &register_list, list)
+                if (!strcmp(t->name, name))
+                        return t;
+
+        return NULL;
+}
+
+static struct dm_cache_policy_type *__get_policy_once(const char *name)
+{
+        struct dm_cache_policy_type *t = __find_policy(name);
+
+        if (t && !try_module_get(t->owner)) {
+                DMWARN("couldn't get module %s", name);
+                t = ERR_PTR(-EINVAL);
+        }
+
+        return t;
+}
+
+static struct dm_cache_policy_type *get_policy_once(const char *name)
+{
+        struct dm_cache_policy_type *t;
+
+        spin_lock(&register_lock);
+        t = __get_policy_once(name);
+        spin_unlock(&register_lock);
+
+        return t;
+}
+
+static struct dm_cache_policy_type *get_policy(const char *name)
+{
+        struct dm_cache_policy_type *t;
+
+        t = get_policy_once(name);
+        if (IS_ERR(t))
+                return NULL;
+
+        if (t)
+                return t;
+
+        request_module("dm-cache-%s", name);
+
+        t = get_policy_once(name);
+        if (IS_ERR(t))
+                return NULL;
+
+        return t;
+}
+
+static void put_policy(struct dm_cache_policy_type *t)
+{
+        module_put(t->owner);
+}
+
+int dm_cache_policy_register(struct dm_cache_policy_type *type)
+{
+        int r;
+
+        /* One size fits all for now */
+        if (type->hint_size != 0 && type->hint_size != 4) {
+                DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size);
+                return -EINVAL;
+        }
+
+        spin_lock(&register_lock);
+        if (__find_policy(type->name)) {
+                DMWARN("attempt to register policy under duplicate name %s", type->name);
+                r = -EINVAL;
+        } else {
+                list_add(&type->list, &register_list);
+                r = 0;
+        }
+        spin_unlock(&register_lock);
+
+        return r;
+}
+EXPORT_SYMBOL_GPL(dm_cache_policy_register);
+
+void dm_cache_policy_unregister(struct dm_cache_policy_type *type)
+{
+        spin_lock(&register_lock);
+        list_del_init(&type->list);
+        spin_unlock(&register_lock);
+}
+EXPORT_SYMBOL_GPL(dm_cache_policy_unregister);
+
+struct dm_cache_policy *dm_cache_policy_create(const char *name,
+                                               dm_cblock_t cache_size,
+                                               sector_t origin_size,
+                                               sector_t cache_block_size)
+{
+        struct dm_cache_policy *p = NULL;
+        struct dm_cache_policy_type *type;
+
+        type = get_policy(name);
+        if (!type) {
+                DMWARN("unknown policy type");
+                return NULL;
+        }
+
+        p = type->create(cache_size, origin_size, cache_block_size);
+        if (!p) {
+                put_policy(type);
+                return NULL;
+        }
+        p->private = type;
+
+        return p;
+}
+EXPORT_SYMBOL_GPL(dm_cache_policy_create);
+
+void dm_cache_policy_destroy(struct dm_cache_policy *p)
+{
+        struct dm_cache_policy_type *t = p->private;
+
+        p->destroy(p);
+        put_policy(t);
+}
+EXPORT_SYMBOL_GPL(dm_cache_policy_destroy);
+
+const char *dm_cache_policy_get_name(struct dm_cache_policy *p)
+{
+        struct dm_cache_policy_type *t = p->private;
+
+        return t->name;
+}
+EXPORT_SYMBOL_GPL(dm_cache_policy_get_name);
+
+size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p)
+{
+        struct dm_cache_policy_type *t = p->private;
+
+        return t->hint_size;
+}
+EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size);
+
+/*----------------------------------------------------------------*/