/* * 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 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 path *(*select_path) (struct path_selector *ps, unsigned *repeat_count); /* * Notify the selector that a path has failed. */ void (*fail_path) (struct path_selector *ps, struct path *p); /* * Ask selector to reinstate a path. */ int (*reinstate_path) (struct path_selector *ps, struct path *p); /* * Table content based on parameters added in ps_add_path_fn * or path selector status */ int (*status) (struct path_selector *ps, struct path *path, status_type_t type, char *result, unsigned int maxlen); int (*end_io) (struct path_selector *ps, struct path *path); }; /* 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