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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2003 Sistina Software.
4 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
5 *
6 * Module Author: Heinz Mauelshagen
7 *
8 * This file is released under the GPL.
9 *
10 * Round-robin path selector.
11 */
12
13#include <linux/device-mapper.h>
14
15#include "dm-path-selector.h"
16
17#include <linux/slab.h>
18#include <linux/module.h>
19
20#define DM_MSG_PREFIX "multipath round-robin"
21#define RR_MIN_IO 1
22#define RR_VERSION "1.2.0"
23
24/*
25 *---------------------------------------------------------------
26 * Path-handling code, paths are held in lists
27 *---------------------------------------------------------------
28 */
29struct path_info {
30 struct list_head list;
31 struct dm_path *path;
32 unsigned int repeat_count;
33};
34
35static void free_paths(struct list_head *paths)
36{
37 struct path_info *pi, *next;
38
39 list_for_each_entry_safe(pi, next, paths, list) {
40 list_del(&pi->list);
41 kfree(pi);
42 }
43}
44
45/*
46 *---------------------------------------------------------------
47 * Round-robin selector
48 *---------------------------------------------------------------
49 */
50struct selector {
51 struct list_head valid_paths;
52 struct list_head invalid_paths;
53 spinlock_t lock;
54};
55
56static struct selector *alloc_selector(void)
57{
58 struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL);
59
60 if (s) {
61 INIT_LIST_HEAD(&s->valid_paths);
62 INIT_LIST_HEAD(&s->invalid_paths);
63 spin_lock_init(&s->lock);
64 }
65
66 return s;
67}
68
69static int rr_create(struct path_selector *ps, unsigned int argc, char **argv)
70{
71 struct selector *s;
72
73 s = alloc_selector();
74 if (!s)
75 return -ENOMEM;
76
77 ps->context = s;
78 return 0;
79}
80
81static void rr_destroy(struct path_selector *ps)
82{
83 struct selector *s = ps->context;
84
85 free_paths(&s->valid_paths);
86 free_paths(&s->invalid_paths);
87 kfree(s);
88 ps->context = NULL;
89}
90
91static int rr_status(struct path_selector *ps, struct dm_path *path,
92 status_type_t type, char *result, unsigned int maxlen)
93{
94 struct path_info *pi;
95 int sz = 0;
96
97 if (!path)
98 DMEMIT("0 ");
99 else {
100 switch (type) {
101 case STATUSTYPE_INFO:
102 break;
103 case STATUSTYPE_TABLE:
104 pi = path->pscontext;
105 DMEMIT("%u ", pi->repeat_count);
106 break;
107
108 case STATUSTYPE_IMA:
109 *result = '\0';
110 break;
111 }
112 }
113
114 return sz;
115}
116
117/*
118 * Called during initialisation to register each path with an
119 * optional repeat_count.
120 */
121static int rr_add_path(struct path_selector *ps, struct dm_path *path,
122 int argc, char **argv, char **error)
123{
124 struct selector *s = ps->context;
125 struct path_info *pi;
126 unsigned int repeat_count = RR_MIN_IO;
127 char dummy;
128 unsigned long flags;
129
130 if (argc > 1) {
131 *error = "round-robin ps: incorrect number of arguments";
132 return -EINVAL;
133 }
134
135 /* First path argument is number of I/Os before switching path */
136 if ((argc == 1) && (sscanf(argv[0], "%u%c", &repeat_count, &dummy) != 1)) {
137 *error = "round-robin ps: invalid repeat count";
138 return -EINVAL;
139 }
140
141 if (repeat_count > 1) {
142 DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead");
143 repeat_count = 1;
144 }
145
146 /* allocate the path */
147 pi = kmalloc(sizeof(*pi), GFP_KERNEL);
148 if (!pi) {
149 *error = "round-robin ps: Error allocating path context";
150 return -ENOMEM;
151 }
152
153 pi->path = path;
154 pi->repeat_count = repeat_count;
155
156 path->pscontext = pi;
157
158 spin_lock_irqsave(&s->lock, flags);
159 list_add_tail(&pi->list, &s->valid_paths);
160 spin_unlock_irqrestore(&s->lock, flags);
161
162 return 0;
163}
164
165static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
166{
167 unsigned long flags;
168 struct selector *s = ps->context;
169 struct path_info *pi = p->pscontext;
170
171 spin_lock_irqsave(&s->lock, flags);
172 list_move(&pi->list, &s->invalid_paths);
173 spin_unlock_irqrestore(&s->lock, flags);
174}
175
176static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
177{
178 unsigned long flags;
179 struct selector *s = ps->context;
180 struct path_info *pi = p->pscontext;
181
182 spin_lock_irqsave(&s->lock, flags);
183 list_move(&pi->list, &s->valid_paths);
184 spin_unlock_irqrestore(&s->lock, flags);
185
186 return 0;
187}
188
189static struct dm_path *rr_select_path(struct path_selector *ps, size_t nr_bytes)
190{
191 unsigned long flags;
192 struct selector *s = ps->context;
193 struct path_info *pi = NULL;
194
195 spin_lock_irqsave(&s->lock, flags);
196 if (!list_empty(&s->valid_paths)) {
197 pi = list_entry(s->valid_paths.next, struct path_info, list);
198 list_move_tail(&pi->list, &s->valid_paths);
199 }
200 spin_unlock_irqrestore(&s->lock, flags);
201
202 return pi ? pi->path : NULL;
203}
204
205static struct path_selector_type rr_ps = {
206 .name = "round-robin",
207 .module = THIS_MODULE,
208 .table_args = 1,
209 .info_args = 0,
210 .create = rr_create,
211 .destroy = rr_destroy,
212 .status = rr_status,
213 .add_path = rr_add_path,
214 .fail_path = rr_fail_path,
215 .reinstate_path = rr_reinstate_path,
216 .select_path = rr_select_path,
217};
218
219static int __init dm_rr_init(void)
220{
221 int r = dm_register_path_selector(&rr_ps);
222
223 if (r < 0)
224 DMERR("register failed %d", r);
225
226 DMINFO("version " RR_VERSION " loaded");
227
228 return r;
229}
230
231static void __exit dm_rr_exit(void)
232{
233 int r = dm_unregister_path_selector(&rr_ps);
234
235 if (r < 0)
236 DMERR("unregister failed %d", r);
237}
238
239module_init(dm_rr_init);
240module_exit(dm_rr_exit);
241
242MODULE_DESCRIPTION(DM_NAME " round-robin multipath path selector");
243MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
244MODULE_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#define RR_MIN_IO 1
21#define RR_VERSION "1.2.0"
22
23/*-----------------------------------------------------------------
24 * Path-handling code, paths are held in lists
25 *---------------------------------------------------------------*/
26struct path_info {
27 struct list_head list;
28 struct dm_path *path;
29 unsigned repeat_count;
30};
31
32static void free_paths(struct list_head *paths)
33{
34 struct path_info *pi, *next;
35
36 list_for_each_entry_safe(pi, next, paths, list) {
37 list_del(&pi->list);
38 kfree(pi);
39 }
40}
41
42/*-----------------------------------------------------------------
43 * Round-robin selector
44 *---------------------------------------------------------------*/
45
46struct selector {
47 struct list_head valid_paths;
48 struct list_head invalid_paths;
49 spinlock_t lock;
50};
51
52static struct selector *alloc_selector(void)
53{
54 struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL);
55
56 if (s) {
57 INIT_LIST_HEAD(&s->valid_paths);
58 INIT_LIST_HEAD(&s->invalid_paths);
59 spin_lock_init(&s->lock);
60 }
61
62 return s;
63}
64
65static int rr_create(struct path_selector *ps, unsigned argc, char **argv)
66{
67 struct selector *s;
68
69 s = alloc_selector();
70 if (!s)
71 return -ENOMEM;
72
73 ps->context = s;
74 return 0;
75}
76
77static void rr_destroy(struct path_selector *ps)
78{
79 struct selector *s = ps->context;
80
81 free_paths(&s->valid_paths);
82 free_paths(&s->invalid_paths);
83 kfree(s);
84 ps->context = NULL;
85}
86
87static int rr_status(struct path_selector *ps, struct dm_path *path,
88 status_type_t type, char *result, unsigned int maxlen)
89{
90 struct path_info *pi;
91 int sz = 0;
92
93 if (!path)
94 DMEMIT("0 ");
95 else {
96 switch(type) {
97 case STATUSTYPE_INFO:
98 break;
99 case STATUSTYPE_TABLE:
100 pi = path->pscontext;
101 DMEMIT("%u ", pi->repeat_count);
102 break;
103
104 case STATUSTYPE_IMA:
105 *result = '\0';
106 break;
107 }
108 }
109
110 return sz;
111}
112
113/*
114 * Called during initialisation to register each path with an
115 * optional repeat_count.
116 */
117static int rr_add_path(struct path_selector *ps, struct dm_path *path,
118 int argc, char **argv, char **error)
119{
120 struct selector *s = ps->context;
121 struct path_info *pi;
122 unsigned repeat_count = RR_MIN_IO;
123 char dummy;
124 unsigned long flags;
125
126 if (argc > 1) {
127 *error = "round-robin ps: incorrect number of arguments";
128 return -EINVAL;
129 }
130
131 /* First path argument is number of I/Os before switching path */
132 if ((argc == 1) && (sscanf(argv[0], "%u%c", &repeat_count, &dummy) != 1)) {
133 *error = "round-robin ps: invalid repeat count";
134 return -EINVAL;
135 }
136
137 if (repeat_count > 1) {
138 DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead");
139 repeat_count = 1;
140 }
141
142 /* allocate the path */
143 pi = kmalloc(sizeof(*pi), GFP_KERNEL);
144 if (!pi) {
145 *error = "round-robin ps: Error allocating path context";
146 return -ENOMEM;
147 }
148
149 pi->path = path;
150 pi->repeat_count = repeat_count;
151
152 path->pscontext = pi;
153
154 spin_lock_irqsave(&s->lock, flags);
155 list_add_tail(&pi->list, &s->valid_paths);
156 spin_unlock_irqrestore(&s->lock, flags);
157
158 return 0;
159}
160
161static void rr_fail_path(struct path_selector *ps, struct dm_path *p)
162{
163 unsigned long flags;
164 struct selector *s = ps->context;
165 struct path_info *pi = p->pscontext;
166
167 spin_lock_irqsave(&s->lock, flags);
168 list_move(&pi->list, &s->invalid_paths);
169 spin_unlock_irqrestore(&s->lock, flags);
170}
171
172static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p)
173{
174 unsigned long flags;
175 struct selector *s = ps->context;
176 struct path_info *pi = p->pscontext;
177
178 spin_lock_irqsave(&s->lock, flags);
179 list_move(&pi->list, &s->valid_paths);
180 spin_unlock_irqrestore(&s->lock, flags);
181
182 return 0;
183}
184
185static struct dm_path *rr_select_path(struct path_selector *ps, size_t nr_bytes)
186{
187 unsigned long flags;
188 struct selector *s = ps->context;
189 struct path_info *pi = NULL;
190
191 spin_lock_irqsave(&s->lock, flags);
192 if (!list_empty(&s->valid_paths)) {
193 pi = list_entry(s->valid_paths.next, struct path_info, list);
194 list_move_tail(&pi->list, &s->valid_paths);
195 }
196 spin_unlock_irqrestore(&s->lock, flags);
197
198 return pi ? pi->path : NULL;
199}
200
201static struct path_selector_type rr_ps = {
202 .name = "round-robin",
203 .module = THIS_MODULE,
204 .table_args = 1,
205 .info_args = 0,
206 .create = rr_create,
207 .destroy = rr_destroy,
208 .status = rr_status,
209 .add_path = rr_add_path,
210 .fail_path = rr_fail_path,
211 .reinstate_path = rr_reinstate_path,
212 .select_path = rr_select_path,
213};
214
215static int __init dm_rr_init(void)
216{
217 int r = dm_register_path_selector(&rr_ps);
218
219 if (r < 0)
220 DMERR("register failed %d", r);
221
222 DMINFO("version " RR_VERSION " loaded");
223
224 return r;
225}
226
227static void __exit dm_rr_exit(void)
228{
229 int r = dm_unregister_path_selector(&rr_ps);
230
231 if (r < 0)
232 DMERR("unregister failed %d", r);
233}
234
235module_init(dm_rr_init);
236module_exit(dm_rr_exit);
237
238MODULE_DESCRIPTION(DM_NAME " round-robin multipath path selector");
239MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
240MODULE_LICENSE("GPL");