From: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
The dm-registry module is a general purpose registry for modules.
The remote replicator utilizes it to register its ringbuffer log and
site link handlers.
Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
Signed-off-by: Zdenek Kabelac <zkabelac@xxxxxxxxxx>
---
drivers/md/dm-registry.c | 224 ++++++++++++++++++++++++++++++++++++++++++++++
drivers/md/dm-registry.h | 38 ++++++++
2 files changed, 262 insertions(+), 0 deletions(-)
create mode 100644 drivers/md/dm-registry.c
create mode 100644 drivers/md/dm-registry.h
diff --git a/drivers/md/dm-registry.c b/drivers/md/dm-registry.c
new file mode 100644
index 0000000..f439e1a
--- /dev/null
+++ b/drivers/md/dm-registry.c
@@ -0,0 +1,224 @@
+/*
+ * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
+ *
+ * Module Author: Heinz Mauelshagen (heinzm@xxxxxxxxxx)
+ *
+ * Generic registry for arbitrary structures
+ * (needs dm_registry_type structure upfront each registered structure).
+ *
+ * This file is released under the GPL.
+ *
+ * FIXME: use as registry for e.g. dirty log types as well.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include "dm-registry.h"
+
+#define DM_MSG_PREFIX "dm-registry"
+
+static const char *version = "0.001";
+
+/* Sizable class registry. */
+static unsigned num_classes;
+static struct list_head *_classes;
+static rwlock_t *_locks;
+
+void *
+dm_get_type(const char *type_name, enum dm_registry_class class)
+{
+ struct dm_registry_type *t;
+
+ read_lock(_locks + class);
+ list_for_each_entry(t, _classes + class, list) {
+ if (!strcmp(type_name, t->name)) {
+ if (!t->use_count && !try_module_get(t->module)) {
+ read_unlock(_locks + class);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ t->use_count++;
+ read_unlock(_locks + class);
+ return t;
+ }
+ }
+
+ read_unlock(_locks + class);
+ return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL(dm_get_type);
+
+void
+dm_put_type(void *type, enum dm_registry_class class)
+{
+ struct dm_registry_type *t = type;
+
+ read_lock(_locks + class);
+ if (!--t->use_count)
+ module_put(t->module);
+
+ read_unlock(_locks + class);
+}
+EXPORT_SYMBOL(dm_put_type);
+
+/* Add a type to the registry. */
+int
+dm_register_type(void *type, enum dm_registry_class class)
+{
+ struct dm_registry_type *t = type, *tt;
+
+ if (unlikely(class >= num_classes))
+ return -EINVAL;
+
+ tt = dm_get_type(t->name, class);
+ if (unlikely(!IS_ERR(tt))) {
+ dm_put_type(t, class);
+ return -EEXIST;
+ }
+
+ write_lock(_locks + class);
+ t->use_count = 0;
+ list_add(&t->list, _classes + class);
+ write_unlock(_locks + class);
+
+ return 0;
+}
+EXPORT_SYMBOL(dm_register_type);
+
+/* Remove a type from the registry. */
+int
+dm_unregister_type(void *type, enum dm_registry_class class)
+{
+ struct dm_registry_type *t = type;
+
+ if (unlikely(class >= num_classes)) {
+ DMERR("Attempt to unregister invalid class");
+ return -EINVAL;
+ }
+
+ write_lock(_locks + class);
+
+ if (unlikely(t->use_count)) {
+ write_unlock(_locks + class);
+ DMWARN("Attempt to unregister a type that is still in use");
+ return -ETXTBSY;
+ } else
+ list_del(&t->list);
+
+ write_unlock(_locks + class);
+ return 0;
+}
+EXPORT_SYMBOL(dm_unregister_type);
+
+/*
+ * Return kmalloc'ed NULL terminated pointer
+ * array of all type names of the given class.
+ *
+ * Caller has to kfree the array!.
+ */
+const char **dm_types_list(enum dm_registry_class class)
+{
+ unsigned i = 0, count = 0;
+ const char **r;
+ struct dm_registry_type *t;
+
+ /* First count the registered types in the class. */
+ read_lock(_locks + class);
+ list_for_each_entry(t, _classes + class, list)
+ count++;
+ read_unlock(_locks + class);
+
+ /* None registered in this class. */
+ if (!count)
+ return NULL;
+
+ /* One member more for array NULL termination. */
+ r = kzalloc((count + 1) * sizeof(*r), GFP_KERNEL);
+ if (!r)
+ return ERR_PTR(-ENOMEM);
+
+ /*
+ * Go with the counted ones.
+ * Any new added ones after we counted will be ignored!
+ */
+ read_lock(_locks + class);
+ list_for_each_entry(t, _classes + class, list) {
+ r[i++] = t->name;
+ if (!--count)
+ break;
+ }
+ read_unlock(_locks + class);
+
+ return r;
+}
+EXPORT_SYMBOL(dm_types_list);
+
+int __init
+dm_registry_init(void)
+{
+ unsigned n;
+
+ BUG_ON(_classes);
+ BUG_ON(_locks);
+
+ /* Module parameter given ? */
+ if (!num_classes)
+ num_classes = DM_REGISTRY_CLASS_END;
+
+ n = num_classes;
+ _classes = kmalloc(n * sizeof(*_classes), GFP_KERNEL);
+ if (!_classes) {
+ DMERR("Failed to allocate classes registry");
+ return -ENOMEM;
+ }
+
+ _locks = kmalloc(n * sizeof(*_locks), GFP_KERNEL);
+ if (!_locks) {
+ DMERR("Failed to allocate classes locks");
+ kfree(_classes);
+ _classes = NULL;
+ return -ENOMEM;
+ }
+
+ while (n--) {
+ INIT_LIST_HEAD(_classes + n);
+ rwlock_init(_locks + n);
+ }
+
+ DMINFO(" initialized %s for max %u classes", version, num_classes);
+ return 0;
+}
+
+void __exit
+dm_registry_exit(void)
+{
+ BUG_ON(!_classes);
+ BUG_ON(!_locks);
+
+ kfree(_classes);
+ _classes = NULL;
+ kfree(_locks);
+ _locks = NULL;
+ DMINFO(" exit %s", version);
+}
+
+/* Module hooks */
+module_init(dm_registry_init);
+module_exit(dm_registry_exit);
+module_param(num_classes, uint, 0);
+MODULE_PARM_DESC(num_classes, "Maximum number of classes");
+MODULE_DESCRIPTION(DM_NAME "device-mapper registry");
+MODULE_AUTHOR("Heinz Mauelshagen <heinzm@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
+
+#ifndef MODULE
+static int __init num_classes_setup(char *str)
+{
+ num_classes = simple_strtol(str, NULL, 0);
+ return num_classes ? 1 : 0;
+}
+
+__setup("num_classes=", num_classes_setup);
+#endif
diff --git a/drivers/md/dm-registry.h b/drivers/md/dm-registry.h
new file mode 100644
index 0000000..2d04314
--- /dev/null
+++ b/drivers/md/dm-registry.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2008 Red Hat, Inc. All rights reserved.
+ *
+ * Module Author: Heinz Mauelshagen (Mauelshagen@xxxxxxxxxx)
+ *
+ * Generic registry for arbitrary structures.
+ * (needs dm_registry_type structure upfront each registered structure).
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+
+#ifndef DM_REGISTRY_H
+#define DM_REGISTRY_H
+
+enum dm_registry_class {
+ DM_REPLOG = 0,
+ DM_SLINK,
+ DM_LOG,
+ DM_REGION_HASH,
+ DM_REGISTRY_CLASS_END,
+};
+
+struct dm_registry_type {
+ struct list_head list; /* Linked list of types in this class. */
+ const char *name;
+ struct module *module;
+ unsigned int use_count;
+};
+
+void *dm_get_type(const char *type_name, enum dm_registry_class class);
+void dm_put_type(void *type, enum dm_registry_class class);
+int dm_register_type(void *type, enum dm_registry_class class);
+int dm_unregister_type(void *type, enum dm_registry_class class);
+const char **dm_types_list(enum dm_registry_class class);
+
+#endif
--
1.6.2.5
--
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