1*4882a593Smuzhiyun /* 2*4882a593Smuzhiyun * Copyright (C) 2003 Sistina Software. 3*4882a593Smuzhiyun * Copyright (C) 2004 Red Hat, Inc. All rights reserved. 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Module Author: Heinz Mauelshagen 6*4882a593Smuzhiyun * 7*4882a593Smuzhiyun * This file is released under the GPL. 8*4882a593Smuzhiyun * 9*4882a593Smuzhiyun * Path-Selector registration. 10*4882a593Smuzhiyun */ 11*4882a593Smuzhiyun 12*4882a593Smuzhiyun #ifndef DM_PATH_SELECTOR_H 13*4882a593Smuzhiyun #define DM_PATH_SELECTOR_H 14*4882a593Smuzhiyun 15*4882a593Smuzhiyun #include <linux/device-mapper.h> 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun #include "dm-mpath.h" 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun /* 20*4882a593Smuzhiyun * We provide an abstraction for the code that chooses which path 21*4882a593Smuzhiyun * to send some io down. 22*4882a593Smuzhiyun */ 23*4882a593Smuzhiyun struct path_selector_type; 24*4882a593Smuzhiyun struct path_selector { 25*4882a593Smuzhiyun struct path_selector_type *type; 26*4882a593Smuzhiyun void *context; 27*4882a593Smuzhiyun }; 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun /* Information about a path selector type */ 30*4882a593Smuzhiyun struct path_selector_type { 31*4882a593Smuzhiyun char *name; 32*4882a593Smuzhiyun struct module *module; 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun unsigned int table_args; 35*4882a593Smuzhiyun unsigned int info_args; 36*4882a593Smuzhiyun 37*4882a593Smuzhiyun /* 38*4882a593Smuzhiyun * Constructs a path selector object, takes custom arguments 39*4882a593Smuzhiyun */ 40*4882a593Smuzhiyun int (*create) (struct path_selector *ps, unsigned argc, char **argv); 41*4882a593Smuzhiyun void (*destroy) (struct path_selector *ps); 42*4882a593Smuzhiyun 43*4882a593Smuzhiyun /* 44*4882a593Smuzhiyun * Add an opaque path object, along with some selector specific 45*4882a593Smuzhiyun * path args (eg, path priority). 46*4882a593Smuzhiyun */ 47*4882a593Smuzhiyun int (*add_path) (struct path_selector *ps, struct dm_path *path, 48*4882a593Smuzhiyun int argc, char **argv, char **error); 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun /* 51*4882a593Smuzhiyun * Chooses a path for this io, if no paths are available then 52*4882a593Smuzhiyun * NULL will be returned. 53*4882a593Smuzhiyun */ 54*4882a593Smuzhiyun struct dm_path *(*select_path) (struct path_selector *ps, 55*4882a593Smuzhiyun size_t nr_bytes); 56*4882a593Smuzhiyun 57*4882a593Smuzhiyun /* 58*4882a593Smuzhiyun * Notify the selector that a path has failed. 59*4882a593Smuzhiyun */ 60*4882a593Smuzhiyun void (*fail_path) (struct path_selector *ps, struct dm_path *p); 61*4882a593Smuzhiyun 62*4882a593Smuzhiyun /* 63*4882a593Smuzhiyun * Ask selector to reinstate a path. 64*4882a593Smuzhiyun */ 65*4882a593Smuzhiyun int (*reinstate_path) (struct path_selector *ps, struct dm_path *p); 66*4882a593Smuzhiyun 67*4882a593Smuzhiyun /* 68*4882a593Smuzhiyun * Table content based on parameters added in ps_add_path_fn 69*4882a593Smuzhiyun * or path selector status 70*4882a593Smuzhiyun */ 71*4882a593Smuzhiyun int (*status) (struct path_selector *ps, struct dm_path *path, 72*4882a593Smuzhiyun status_type_t type, char *result, unsigned int maxlen); 73*4882a593Smuzhiyun 74*4882a593Smuzhiyun int (*start_io) (struct path_selector *ps, struct dm_path *path, 75*4882a593Smuzhiyun size_t nr_bytes); 76*4882a593Smuzhiyun int (*end_io) (struct path_selector *ps, struct dm_path *path, 77*4882a593Smuzhiyun size_t nr_bytes, u64 start_time); 78*4882a593Smuzhiyun }; 79*4882a593Smuzhiyun 80*4882a593Smuzhiyun /* Register a path selector */ 81*4882a593Smuzhiyun int dm_register_path_selector(struct path_selector_type *type); 82*4882a593Smuzhiyun 83*4882a593Smuzhiyun /* Unregister a path selector */ 84*4882a593Smuzhiyun int dm_unregister_path_selector(struct path_selector_type *type); 85*4882a593Smuzhiyun 86*4882a593Smuzhiyun /* Returns a registered path selector type */ 87*4882a593Smuzhiyun struct path_selector_type *dm_get_path_selector(const char *name); 88*4882a593Smuzhiyun 89*4882a593Smuzhiyun /* Releases a path selector */ 90*4882a593Smuzhiyun void dm_put_path_selector(struct path_selector_type *pst); 91*4882a593Smuzhiyun 92*4882a593Smuzhiyun #endif 93