Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / drivers / md / dm-path-selector.h

diff --git a/kernel/drivers/md/dm-path-selector.h b/kernel/drivers/md/dm-path-selector.h
new file mode 100644 (file)
index 0000000..e7d1fa8
--- /dev/null
+++ b/kernel/drivers/md/dm-path-selector.h
@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+#ifndef        DM_PATH_SELECTOR_H
+#define        DM_PATH_SELECTOR_H
+
+#include <linux/device-mapper.h>
+
+#include "dm-mpath.h"
+
+/*
+ * We provide an abstraction for the code that chooses which path
+ * to send some io down.
+ */
+struct path_selector_type;
+struct path_selector {
+       struct path_selector_type *type;
+       void *context;
+};
+
+/* Information about a path selector type */
+struct path_selector_type {
+       char *name;
+       struct module *module;
+
+       unsigned int table_args;
+       unsigned int info_args;
+
+       /*
+        * Constructs a path selector object, takes custom arguments
+        */
+       int (*create) (struct path_selector *ps, unsigned argc, char **argv);
+       void (*destroy) (struct path_selector *ps);
+
+       /*
+        * Add an opaque path object, along with some selector specific
+        * path args (eg, path priority).
+        */
+       int (*add_path) (struct path_selector *ps, struct dm_path *path,
+                        int argc, char **argv, char **error);
+
+       /*
+        * Chooses a path for this io, if no paths are available then
+        * NULL will be returned.
+        *
+        * repeat_count is the number of times to use the path before
+        * calling the function again.  0 means don't call it again unless
+        * the path fails.
+        */
+       struct dm_path *(*select_path) (struct path_selector *ps,
+                                       unsigned *repeat_count,
+                                       size_t nr_bytes);
+
+       /*
+        * Notify the selector that a path has failed.
+        */
+       void (*fail_path) (struct path_selector *ps, struct dm_path *p);
+
+       /*
+        * Ask selector to reinstate a path.
+        */
+       int (*reinstate_path) (struct path_selector *ps, struct dm_path *p);
+
+       /*
+        * Table content based on parameters added in ps_add_path_fn
+        * or path selector status
+        */
+       int (*status) (struct path_selector *ps, struct dm_path *path,
+                      status_type_t type, char *result, unsigned int maxlen);
+
+       int (*start_io) (struct path_selector *ps, struct dm_path *path,
+                        size_t nr_bytes);
+       int (*end_io) (struct path_selector *ps, struct dm_path *path,
+                      size_t nr_bytes);
+};
+
+/* Register a path selector */
+int dm_register_path_selector(struct path_selector_type *type);
+
+/* Unregister a path selector */
+int dm_unregister_path_selector(struct path_selector_type *type);
+
+/* Returns a registered path selector type */
+struct path_selector_type *dm_get_path_selector(const char *name);
+
+/* Releases a path selector  */
+void dm_put_path_selector(struct path_selector_type *pst);
+
+#endif