Commit | Line | Data |
---|---|---|
1da177e4 LT |
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 | ||
586e80e6 MP |
12 | #include <linux/device-mapper.h> |
13 | ||
1da177e4 LT |
14 | #include "dm-path-selector.h" |
15 | ||
16 | #include <linux/slab.h> | |
056075c7 | 17 | #include <linux/module.h> |
1da177e4 | 18 | |
72d94861 | 19 | #define DM_MSG_PREFIX "multipath round-robin" |
37a098e9 MS |
20 | #define RR_MIN_IO 1 |
21 | #define RR_VERSION "1.2.0" | |
72d94861 | 22 | |
1da177e4 LT |
23 | /*----------------------------------------------------------------- |
24 | * Path-handling code, paths are held in lists | |
25 | *---------------------------------------------------------------*/ | |
26 | struct path_info { | |
27 | struct list_head list; | |
c922d5f7 | 28 | struct dm_path *path; |
1da177e4 LT |
29 | unsigned repeat_count; |
30 | }; | |
31 | ||
32 | static 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 | ||
1da177e4 LT |
46 | struct selector { |
47 | struct list_head valid_paths; | |
48 | struct list_head invalid_paths; | |
9659f811 | 49 | spinlock_t lock; |
1da177e4 LT |
50 | }; |
51 | ||
52 | static struct selector *alloc_selector(void) | |
53 | { | |
54 | struct selector *s = kmalloc(sizeof(*s), GFP_KERNEL); | |
55 | ||
37a098e9 MS |
56 | if (s) { |
57 | INIT_LIST_HEAD(&s->valid_paths); | |
58 | INIT_LIST_HEAD(&s->invalid_paths); | |
59 | spin_lock_init(&s->lock); | |
60 | } | |
1da177e4 LT |
61 | |
62 | return s; | |
63 | } | |
64 | ||
65 | static 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 | ||
77 | static void rr_destroy(struct path_selector *ps) | |
78 | { | |
9659f811 | 79 | struct selector *s = ps->context; |
1da177e4 LT |
80 | |
81 | free_paths(&s->valid_paths); | |
82 | free_paths(&s->invalid_paths); | |
83 | kfree(s); | |
84 | ps->context = NULL; | |
85 | } | |
86 | ||
c922d5f7 | 87 | static int rr_status(struct path_selector *ps, struct dm_path *path, |
1da177e4 LT |
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 | } | |
105 | ||
106 | return sz; | |
107 | } | |
108 | ||
109 | /* | |
110 | * Called during initialisation to register each path with an | |
111 | * optional repeat_count. | |
112 | */ | |
c922d5f7 | 113 | static int rr_add_path(struct path_selector *ps, struct dm_path *path, |
1da177e4 LT |
114 | int argc, char **argv, char **error) |
115 | { | |
9659f811 | 116 | struct selector *s = ps->context; |
1da177e4 LT |
117 | struct path_info *pi; |
118 | unsigned repeat_count = RR_MIN_IO; | |
31998ef1 | 119 | char dummy; |
9659f811 | 120 | unsigned long flags; |
1da177e4 LT |
121 | |
122 | if (argc > 1) { | |
123 | *error = "round-robin ps: incorrect number of arguments"; | |
124 | return -EINVAL; | |
125 | } | |
126 | ||
127 | /* First path argument is number of I/Os before switching path */ | |
31998ef1 | 128 | if ((argc == 1) && (sscanf(argv[0], "%u%c", &repeat_count, &dummy) != 1)) { |
1da177e4 LT |
129 | *error = "round-robin ps: invalid repeat count"; |
130 | return -EINVAL; | |
131 | } | |
132 | ||
37a098e9 MS |
133 | if (repeat_count > 1) { |
134 | DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead"); | |
135 | repeat_count = 1; | |
136 | } | |
137 | ||
1da177e4 LT |
138 | /* allocate the path */ |
139 | pi = kmalloc(sizeof(*pi), GFP_KERNEL); | |
140 | if (!pi) { | |
141 | *error = "round-robin ps: Error allocating path context"; | |
142 | return -ENOMEM; | |
143 | } | |
144 | ||
145 | pi->path = path; | |
146 | pi->repeat_count = repeat_count; | |
147 | ||
148 | path->pscontext = pi; | |
149 | ||
9659f811 | 150 | spin_lock_irqsave(&s->lock, flags); |
5d55fdf9 | 151 | list_add_tail(&pi->list, &s->valid_paths); |
9659f811 | 152 | spin_unlock_irqrestore(&s->lock, flags); |
1da177e4 LT |
153 | |
154 | return 0; | |
155 | } | |
156 | ||
c922d5f7 | 157 | static void rr_fail_path(struct path_selector *ps, struct dm_path *p) |
1da177e4 | 158 | { |
9659f811 MS |
159 | unsigned long flags; |
160 | struct selector *s = ps->context; | |
1da177e4 LT |
161 | struct path_info *pi = p->pscontext; |
162 | ||
9659f811 | 163 | spin_lock_irqsave(&s->lock, flags); |
1da177e4 | 164 | list_move(&pi->list, &s->invalid_paths); |
9659f811 | 165 | spin_unlock_irqrestore(&s->lock, flags); |
1da177e4 LT |
166 | } |
167 | ||
c922d5f7 | 168 | static int rr_reinstate_path(struct path_selector *ps, struct dm_path *p) |
1da177e4 | 169 | { |
9659f811 MS |
170 | unsigned long flags; |
171 | struct selector *s = ps->context; | |
1da177e4 LT |
172 | struct path_info *pi = p->pscontext; |
173 | ||
9659f811 | 174 | spin_lock_irqsave(&s->lock, flags); |
1da177e4 | 175 | list_move(&pi->list, &s->valid_paths); |
9659f811 | 176 | spin_unlock_irqrestore(&s->lock, flags); |
1da177e4 LT |
177 | |
178 | return 0; | |
179 | } | |
180 | ||
90a4323c | 181 | static struct dm_path *rr_select_path(struct path_selector *ps, size_t nr_bytes) |
1da177e4 | 182 | { |
9659f811 MS |
183 | unsigned long flags; |
184 | struct selector *s = ps->context; | |
1da177e4 LT |
185 | struct path_info *pi = NULL; |
186 | ||
37a098e9 | 187 | spin_lock_irqsave(&s->lock, flags); |
1da177e4 LT |
188 | if (!list_empty(&s->valid_paths)) { |
189 | pi = list_entry(s->valid_paths.next, struct path_info, list); | |
190 | list_move_tail(&pi->list, &s->valid_paths); | |
1da177e4 | 191 | } |
9659f811 | 192 | spin_unlock_irqrestore(&s->lock, flags); |
1da177e4 | 193 | |
37a098e9 | 194 | return pi ? pi->path : NULL; |
1da177e4 LT |
195 | } |
196 | ||
197 | static struct path_selector_type rr_ps = { | |
198 | .name = "round-robin", | |
199 | .module = THIS_MODULE, | |
200 | .table_args = 1, | |
201 | .info_args = 0, | |
202 | .create = rr_create, | |
203 | .destroy = rr_destroy, | |
204 | .status = rr_status, | |
205 | .add_path = rr_add_path, | |
206 | .fail_path = rr_fail_path, | |
207 | .reinstate_path = rr_reinstate_path, | |
208 | .select_path = rr_select_path, | |
209 | }; | |
210 | ||
211 | static int __init dm_rr_init(void) | |
212 | { | |
213 | int r = dm_register_path_selector(&rr_ps); | |
214 | ||
215 | if (r < 0) | |
72d94861 | 216 | DMERR("register failed %d", r); |
1da177e4 | 217 | |
21136f89 | 218 | DMINFO("version " RR_VERSION " loaded"); |
1da177e4 LT |
219 | |
220 | return r; | |
221 | } | |
222 | ||
223 | static void __exit dm_rr_exit(void) | |
224 | { | |
225 | int r = dm_unregister_path_selector(&rr_ps); | |
226 | ||
227 | if (r < 0) | |
0cd33124 | 228 | DMERR("unregister failed %d", r); |
1da177e4 LT |
229 | } |
230 | ||
231 | module_init(dm_rr_init); | |
232 | module_exit(dm_rr_exit); | |
233 | ||
234 | MODULE_DESCRIPTION(DM_NAME " round-robin multipath path selector"); | |
235 | MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); | |
236 | MODULE_LICENSE("GPL"); |