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path: root/drivers/md/dm-path-selector.c
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Diffstat (limited to 'drivers/md/dm-path-selector.c')
-rw-r--r--drivers/md/dm-path-selector.c140
1 files changed, 140 insertions, 0 deletions
diff --git a/drivers/md/dm-path-selector.c b/drivers/md/dm-path-selector.c
new file mode 100644
index 000000000..fa0ccc585
--- /dev/null
+++ b/drivers/md/dm-path-selector.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2003 Sistina Software.
+ * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ *
+ * Module Author: Heinz Mauelshagen
+ *
+ * This file is released under the GPL.
+ *
+ * Path selector registration.
+ */
+
+#include <linux/device-mapper.h>
+#include <linux/module.h>
+
+#include "dm-path-selector.h"
+
+#include <linux/slab.h>
+
+struct ps_internal {
+ struct path_selector_type pst;
+ struct list_head list;
+};
+
+#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
+
+static LIST_HEAD(_path_selectors);
+static DECLARE_RWSEM(_ps_lock);
+
+static struct ps_internal *__find_path_selector_type(const char *name)
+{
+ struct ps_internal *psi;
+
+ list_for_each_entry(psi, &_path_selectors, list) {
+ if (!strcmp(name, psi->pst.name))
+ return psi;
+ }
+
+ return NULL;
+}
+
+static struct ps_internal *get_path_selector(const char *name)
+{
+ struct ps_internal *psi;
+
+ down_read(&_ps_lock);
+ psi = __find_path_selector_type(name);
+ if (psi && !try_module_get(psi->pst.module))
+ psi = NULL;
+ up_read(&_ps_lock);
+
+ return psi;
+}
+
+struct path_selector_type *dm_get_path_selector(const char *name)
+{
+ struct ps_internal *psi;
+
+ if (!name)
+ return NULL;
+
+ psi = get_path_selector(name);
+ if (!psi) {
+ request_module("dm-%s", name);
+ psi = get_path_selector(name);
+ }
+
+ return psi ? &psi->pst : NULL;
+}
+
+void dm_put_path_selector(struct path_selector_type *pst)
+{
+ struct ps_internal *psi;
+
+ if (!pst)
+ return;
+
+ down_read(&_ps_lock);
+ psi = __find_path_selector_type(pst->name);
+ if (!psi)
+ goto out;
+
+ module_put(psi->pst.module);
+out:
+ up_read(&_ps_lock);
+}
+
+static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst)
+{
+ struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL);
+
+ if (psi)
+ psi->pst = *pst;
+
+ return psi;
+}
+
+int dm_register_path_selector(struct path_selector_type *pst)
+{
+ int r = 0;
+ struct ps_internal *psi = _alloc_path_selector(pst);
+
+ if (!psi)
+ return -ENOMEM;
+
+ down_write(&_ps_lock);
+
+ if (__find_path_selector_type(pst->name)) {
+ kfree(psi);
+ r = -EEXIST;
+ } else
+ list_add(&psi->list, &_path_selectors);
+
+ up_write(&_ps_lock);
+
+ return r;
+}
+
+int dm_unregister_path_selector(struct path_selector_type *pst)
+{
+ struct ps_internal *psi;
+
+ down_write(&_ps_lock);
+
+ psi = __find_path_selector_type(pst->name);
+ if (!psi) {
+ up_write(&_ps_lock);
+ return -EINVAL;
+ }
+
+ list_del(&psi->list);
+
+ up_write(&_ps_lock);
+
+ kfree(psi);
+
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(dm_register_path_selector);
+EXPORT_SYMBOL_GPL(dm_unregister_path_selector);