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1/*
2 * Copyright (C) 2003 Sistina Software.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * Module Author: Heinz Mauelshagen
6 *
7 * This file is released under the GPL.
8 *
9 * Round-robin path selector.
10 */
11
12#include <linux/device-mapper.h>
13
14#include "dm-path-selector.h"
15
16#include <linux/slab.h>
17
18#define DM_MSG_PREFIX "multipath round-robin"
19
20/*-----------------------------------------------------------------
21 * Path-handling code, paths are held in lists
22 *---------------------------------------------------------------*/
23struct path_info {
24 struct list_head list;
25 struct dm_path *path;
26 unsigned repeat_count;
27};
28
29static void free_paths(struct list_head *paths)
30{
31 struct path_info *pi, *next;
32
33 list_for_each_entry_safe(pi, next, paths, list) {
34 list_del(&pi->list);
35 kfree(pi);
36 }
37}
38
39/*-----------------------------------------------------------------
40 * Round-robin selector
41 *---------------------------------------------------------------*/
42
43#define RR_MIN_IO 1000
44
45struct selector {
46 struct list_head valid_paths;
47 struct list_head invalid_paths;
48};
49
50static struct selector *alloc_selector(void)
51{
52 struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL);
53
54 if (s) {
55 INIT_LIST_HEAD(&s->valid_paths);
56 INIT_LIST_HEAD(&s->invalid_paths);
57 }
58
59 return s;
60}
61
62static int rr_create(struct path_selector *ps, unsigned argc, char **argv)
63{
64 struct selector *s;
65
66 s = alloc_selector();
67 if (!s)
68 return -ENOMEM;
69
70 ps->context = s;
71 return 0;
72}
73
74static void rr_destroy(struct path_selector *ps)
75{
76 struct selector *s = (struct selector *) ps->context;
77
78 free_paths(&s->valid_paths);
79 free_paths(&s->invalid_paths);
80 kfree(s);
81 ps->context = NULL;
82}
83
84static int rr_status(struct path_selector *ps, struct dm_path *path,
85 status_type_t type, char *result, unsigned int maxlen)
86{
87 struct path_info *pi;
88 int sz = 0;
89
90 if (!path)
91 DMEMIT("0 ");
92 else {
93 switch(type) {
94 case STATUSTYPE_INFO:
95 break;
96 case STATUSTYPE_TABLE:
97 pi = path->pscontext;
98 DMEMIT("%u ", pi->repeat_count);
99 break;
100 }
101 }
102
103 return sz;
104}
105
106/*
107 * Called during initialisation to register each path with an
108 * optional repeat_count.
109 */
110static int rr_add_path(struct path_selector *ps, struct dm_path *path,
111 int argc, char **argv, char **error)
112{
113 struct selector *s = (struct selector *) ps->context;
114 struct path_info *pi;
115 unsigned repeat_count = RR_MIN_IO;
116
117 if (argc > 1) {
118 *error = "round-robin ps: incorrect number of arguments";
119 return -EINVAL;
120 }
121
122 /* First path argument is number of I/Os before switching path */
123 if ((argc == 1) && (sscanf(argv[0], "%u", &repeat_count) != 1)) {
124 *error = "round-robin ps: invalid repeat count";
125 return -EINVAL;
126 }
127
128 /* allocate the path */
129 pi = kmalloc(sizeof(*pi), GFP_KERNEL);
130 if (!pi) {
131 *error = "round-robin ps: Error allocating path context";
132 return -ENOMEM;
133 }
134
135 pi->path = path;
136 pi->repeat_count = repeat_count;
137
138 path->pscontext = pi;
139
140 list_add_tail(&pi->list, &s->valid_paths);
141
142 return 0;
143}
144
145static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
146{
147 struct selector *s = (struct selector *) ps->context;
148 struct path_info *pi = p->pscontext;
149
150 list_move(&pi->list, &s->invalid_paths);
151}
152
153static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
154{
155 struct selector *s = (struct selector *) ps->context;
156 struct path_info *pi = p->pscontext;
157
158 list_move(&pi->list, &s->valid_paths);
159
160 return 0;
161}
162
163static struct dm_path *rr_select_path(struct path_selector *ps,
164 unsigned *repeat_count, size_t nr_bytes)
165{
166 struct selector *s = (struct selector *) ps->context;
167 struct path_info *pi = NULL;
168
169 if (!list_empty(&s->valid_paths)) {
170 pi = list_entry(s->valid_paths.next, struct path_info, list);
171 list_move_tail(&pi->list, &s->valid_paths);
172 *repeat_count = pi->repeat_count;
173 }
174
175 return pi ? pi->path : NULL;
176}
177
178static struct path_selector_type rr_ps = {
179 .name = "round-robin",
180 .module = THIS_MODULE,
181 .table_args = 1,
182 .info_args = 0,
183 .create = rr_create,
184 .destroy = rr_destroy,
185 .status = rr_status,
186 .add_path = rr_add_path,
187 .fail_path = rr_fail_path,
188 .reinstate_path = rr_reinstate_path,
189 .select_path = rr_select_path,
190};
191
192static int __init dm_rr_init(void)
193{
194 int r = dm_register_path_selector(&rr_ps);
195
196 if (r < 0)
197 DMERR("register failed %d", r);
198
199 DMINFO("version 1.0.0 loaded");
200
201 return r;
202}
203
204static void __exit dm_rr_exit(void)
205{
206 int r = dm_unregister_path_selector(&rr_ps);
207
208 if (r < 0)
209 DMERR("unregister failed %d", r);
210}
211
212module_init(dm_rr_init);
213module_exit(dm_rr_exit);
214
215MODULE_DESCRIPTION(DM_NAME " round-robin multipath path selector");
216MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
217MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2003 Sistina Software.
3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
4 *
5 * Module Author: Heinz Mauelshagen
6 *
7 * This file is released under the GPL.
8 *
9 * Round-robin path selector.
10 */
11
12#include <linux/device-mapper.h>
13
14#include "dm-path-selector.h"
15
16#include <linux/slab.h>
17#include <linux/module.h>
18
19#define DM_MSG_PREFIX "multipath round-robin"
20
21/*-----------------------------------------------------------------
22 * Path-handling code, paths are held in lists
23 *---------------------------------------------------------------*/
24struct path_info {
25 struct list_head list;
26 struct dm_path *path;
27 unsigned repeat_count;
28};
29
30static void free_paths(struct list_head *paths)
31{
32 struct path_info *pi, *next;
33
34 list_for_each_entry_safe(pi, next, paths, list) {
35 list_del(&pi->list);
36 kfree(pi);
37 }
38}
39
40/*-----------------------------------------------------------------
41 * Round-robin selector
42 *---------------------------------------------------------------*/
43
44#define RR_MIN_IO 1000
45
46struct selector {
47 struct list_head valid_paths;
48 struct list_head invalid_paths;
49};
50
51static struct selector *alloc_selector(void)
52{
53 struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL);
54
55 if (s) {
56 INIT_LIST_HEAD(&s->valid_paths);
57 INIT_LIST_HEAD(&s->invalid_paths);
58 }
59
60 return s;
61}
62
63static int rr_create(struct path_selector *ps, unsigned argc, char **argv)
64{
65 struct selector *s;
66
67 s = alloc_selector();
68 if (!s)
69 return -ENOMEM;
70
71 ps->context = s;
72 return 0;
73}
74
75static void rr_destroy(struct path_selector *ps)
76{
77 struct selector *s = (struct selector *) ps->context;
78
79 free_paths(&s->valid_paths);
80 free_paths(&s->invalid_paths);
81 kfree(s);
82 ps->context = NULL;
83}
84
85static int rr_status(struct path_selector *ps, struct dm_path *path,
86 status_type_t type, char *result, unsigned int maxlen)
87{
88 struct path_info *pi;
89 int sz = 0;
90
91 if (!path)
92 DMEMIT("0 ");
93 else {
94 switch(type) {
95 case STATUSTYPE_INFO:
96 break;
97 case STATUSTYPE_TABLE:
98 pi = path->pscontext;
99 DMEMIT("%u ", pi->repeat_count);
100 break;
101 }
102 }
103
104 return sz;
105}
106
107/*
108 * Called during initialisation to register each path with an
109 * optional repeat_count.
110 */
111static int rr_add_path(struct path_selector *ps, struct dm_path *path,
112 int argc, char **argv, char **error)
113{
114 struct selector *s = (struct selector *) ps->context;
115 struct path_info *pi;
116 unsigned repeat_count = RR_MIN_IO;
117 char dummy;
118
119 if (argc > 1) {
120 *error = "round-robin ps: incorrect number of arguments";
121 return -EINVAL;
122 }
123
124 /* First path argument is number of I/Os before switching path */
125 if ((argc == 1) && (sscanf(argv[0], "%u%c", &repeat_count, &dummy) != 1)) {
126 *error = "round-robin ps: invalid repeat count";
127 return -EINVAL;
128 }
129
130 /* allocate the path */
131 pi = kmalloc(sizeof(*pi), GFP_KERNEL);
132 if (!pi) {
133 *error = "round-robin ps: Error allocating path context";
134 return -ENOMEM;
135 }
136
137 pi->path = path;
138 pi->repeat_count = repeat_count;
139
140 path->pscontext = pi;
141
142 list_add_tail(&pi->list, &s->valid_paths);
143
144 return 0;
145}
146
147static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
148{
149 struct selector *s = (struct selector *) ps->context;
150 struct path_info *pi = p->pscontext;
151
152 list_move(&pi->list, &s->invalid_paths);
153}
154
155static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
156{
157 struct selector *s = (struct selector *) ps->context;
158 struct path_info *pi = p->pscontext;
159
160 list_move(&pi->list, &s->valid_paths);
161
162 return 0;
163}
164
165static struct dm_path *rr_select_path(struct path_selector *ps,
166 unsigned *repeat_count, size_t nr_bytes)
167{
168 struct selector *s = (struct selector *) ps->context;
169 struct path_info *pi = NULL;
170
171 if (!list_empty(&s->valid_paths)) {
172 pi = list_entry(s->valid_paths.next, struct path_info, list);
173 list_move_tail(&pi->list, &s->valid_paths);
174 *repeat_count = pi->repeat_count;
175 }
176
177 return pi ? pi->path : NULL;
178}
179
180static struct path_selector_type rr_ps = {
181 .name = "round-robin",
182 .module = THIS_MODULE,
183 .table_args = 1,
184 .info_args = 0,
185 .create = rr_create,
186 .destroy = rr_destroy,
187 .status = rr_status,
188 .add_path = rr_add_path,
189 .fail_path = rr_fail_path,
190 .reinstate_path = rr_reinstate_path,
191 .select_path = rr_select_path,
192};
193
194static int __init dm_rr_init(void)
195{
196 int r = dm_register_path_selector(&rr_ps);
197
198 if (r < 0)
199 DMERR("register failed %d", r);
200
201 DMINFO("version 1.0.0 loaded");
202
203 return r;
204}
205
206static void __exit dm_rr_exit(void)
207{
208 int r = dm_unregister_path_selector(&rr_ps);
209
210 if (r < 0)
211 DMERR("unregister failed %d", r);
212}
213
214module_init(dm_rr_init);
215module_exit(dm_rr_exit);
216
217MODULE_DESCRIPTION(DM_NAME " round-robin multipath path selector");
218MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
219MODULE_LICENSE("GPL");