]>
git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - drivers/md/dm-round-robin.c
2 * Copyright (C) 2003 Sistina Software.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
5 * Module Author: Heinz Mauelshagen
7 * This file is released under the GPL.
9 * Round-robin path selector.
13 #include "dm-path-selector.h"
15 #include <linux/slab.h>
17 #define DM_MSG_PREFIX "multipath round-robin"
19 /*-----------------------------------------------------------------
20 * Path-handling code, paths are held in lists
21 *---------------------------------------------------------------*/
23 struct list_head list
;
25 unsigned repeat_count
;
28 static void free_paths(struct list_head
*paths
)
30 struct path_info
*pi
, *next
;
32 list_for_each_entry_safe(pi
, next
, paths
, list
) {
38 /*-----------------------------------------------------------------
39 * Round-robin selector
40 *---------------------------------------------------------------*/
42 #define RR_MIN_IO 1000
45 struct list_head valid_paths
;
46 struct list_head invalid_paths
;
49 static struct selector
*alloc_selector(void)
51 struct selector
*s
= kmalloc(sizeof(*s
), GFP_KERNEL
);
54 INIT_LIST_HEAD(&s
->valid_paths
);
55 INIT_LIST_HEAD(&s
->invalid_paths
);
61 static int rr_create(struct path_selector
*ps
, unsigned argc
, char **argv
)
73 static void rr_destroy(struct path_selector
*ps
)
75 struct selector
*s
= (struct selector
*) ps
->context
;
77 free_paths(&s
->valid_paths
);
78 free_paths(&s
->invalid_paths
);
83 static int rr_status(struct path_selector
*ps
, struct dm_path
*path
,
84 status_type_t type
, char *result
, unsigned int maxlen
)
95 case STATUSTYPE_TABLE
:
97 DMEMIT("%u ", pi
->repeat_count
);
106 * Called during initialisation to register each path with an
107 * optional repeat_count.
109 static int rr_add_path(struct path_selector
*ps
, struct dm_path
*path
,
110 int argc
, char **argv
, char **error
)
112 struct selector
*s
= (struct selector
*) ps
->context
;
113 struct path_info
*pi
;
114 unsigned repeat_count
= RR_MIN_IO
;
117 *error
= "round-robin ps: incorrect number of arguments";
121 /* First path argument is number of I/Os before switching path */
122 if ((argc
== 1) && (sscanf(argv
[0], "%u", &repeat_count
) != 1)) {
123 *error
= "round-robin ps: invalid repeat count";
127 /* allocate the path */
128 pi
= kmalloc(sizeof(*pi
), GFP_KERNEL
);
130 *error
= "round-robin ps: Error allocating path context";
135 pi
->repeat_count
= repeat_count
;
137 path
->pscontext
= pi
;
139 list_add_tail(&pi
->list
, &s
->valid_paths
);
144 static void rr_fail_path(struct path_selector
*ps
, struct dm_path
*p
)
146 struct selector
*s
= (struct selector
*) ps
->context
;
147 struct path_info
*pi
= p
->pscontext
;
149 list_move(&pi
->list
, &s
->invalid_paths
);
152 static int rr_reinstate_path(struct path_selector
*ps
, struct dm_path
*p
)
154 struct selector
*s
= (struct selector
*) ps
->context
;
155 struct path_info
*pi
= p
->pscontext
;
157 list_move(&pi
->list
, &s
->valid_paths
);
162 static struct dm_path
*rr_select_path(struct path_selector
*ps
,
163 unsigned *repeat_count
)
165 struct selector
*s
= (struct selector
*) ps
->context
;
166 struct path_info
*pi
= NULL
;
168 if (!list_empty(&s
->valid_paths
)) {
169 pi
= list_entry(s
->valid_paths
.next
, struct path_info
, list
);
170 list_move_tail(&pi
->list
, &s
->valid_paths
);
171 *repeat_count
= pi
->repeat_count
;
174 return pi
? pi
->path
: NULL
;
177 static struct path_selector_type rr_ps
= {
178 .name
= "round-robin",
179 .module
= THIS_MODULE
,
183 .destroy
= rr_destroy
,
185 .add_path
= rr_add_path
,
186 .fail_path
= rr_fail_path
,
187 .reinstate_path
= rr_reinstate_path
,
188 .select_path
= rr_select_path
,
191 static int __init
dm_rr_init(void)
193 int r
= dm_register_path_selector(&rr_ps
);
196 DMERR("register failed %d", r
);
198 DMINFO("version 1.0.0 loaded");
203 static void __exit
dm_rr_exit(void)
205 int r
= dm_unregister_path_selector(&rr_ps
);
208 DMERR("unregister failed %d", r
);
211 module_init(dm_rr_init
);
212 module_exit(dm_rr_exit
);
214 MODULE_DESCRIPTION(DM_NAME
" round-robin multipath path selector");
215 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
216 MODULE_LICENSE("GPL");