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path: root/drivers/md/dm-cache-policy.c
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Diffstat (limited to 'drivers/md/dm-cache-policy.c')
-rw-r--r--drivers/md/dm-cache-policy.c161
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);
+
+/*----------------------------------------------------------------*/