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1da177e4 LT |
1 | /* |
2 | * faulty.c : Multiple Devices driver for Linux | |
3 | * | |
4 | * Copyright (C) 2004 Neil Brown | |
5 | * | |
6 | * fautly-device-simulator personality for md | |
7 | * | |
8 | * | |
9 | * This program is free software; you can redistribute it and/or modify | |
10 | * it under the terms of the GNU General Public License as published by | |
11 | * the Free Software Foundation; either version 2, or (at your option) | |
12 | * any later version. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * (for example /usr/src/linux/COPYING); if not, write to the Free | |
16 | * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
17 | */ | |
18 | ||
19 | ||
20 | /* | |
21 | * The "faulty" personality causes some requests to fail. | |
22 | * | |
23 | * Possible failure modes are: | |
24 | * reads fail "randomly" but succeed on retry | |
25 | * writes fail "randomly" but succeed on retry | |
26 | * reads for some address fail and then persist until a write | |
27 | * reads for some address fail and then persist irrespective of write | |
28 | * writes for some address fail and persist | |
29 | * all writes fail | |
30 | * | |
31 | * Different modes can be active at a time, but only | |
32 | * one can be set at array creation. Others can be added later. | |
33 | * A mode can be one-shot or recurrent with the recurrance being | |
34 | * once in every N requests. | |
35 | * The bottom 5 bits of the "layout" indicate the mode. The | |
36 | * remainder indicate a period, or 0 for one-shot. | |
37 | * | |
38 | * There is an implementation limit on the number of concurrently | |
39 | * persisting-faulty blocks. When a new fault is requested that would | |
40 | * exceed the limit, it is ignored. | |
41 | * All current faults can be clear using a layout of "0". | |
42 | * | |
43 | * Requests are always sent to the device. If they are to fail, | |
44 | * we clone the bio and insert a new b_end_io into the chain. | |
45 | */ | |
46 | ||
47 | #define WriteTransient 0 | |
48 | #define ReadTransient 1 | |
49 | #define WritePersistent 2 | |
50 | #define ReadPersistent 3 | |
51 | #define WriteAll 4 /* doesn't go to device */ | |
52 | #define ReadFixable 5 | |
53 | #define Modes 6 | |
54 | ||
55 | #define ClearErrors 31 | |
56 | #define ClearFaults 30 | |
57 | ||
58 | #define AllPersist 100 /* internal use only */ | |
59 | #define NoPersist 101 | |
60 | ||
61 | #define ModeMask 0x1f | |
62 | #define ModeShift 5 | |
63 | ||
64 | #define MaxFault 50 | |
65 | #include <linux/raid/md.h> | |
66 | ||
67 | ||
6712ecf8 | 68 | static void faulty_fail(struct bio *bio, int error) |
1da177e4 LT |
69 | { |
70 | struct bio *b = bio->bi_private; | |
71 | ||
72 | b->bi_size = bio->bi_size; | |
73 | b->bi_sector = bio->bi_sector; | |
74 | ||
6712ecf8 | 75 | bio_put(bio); |
1da177e4 | 76 | |
6712ecf8 | 77 | bio_io_error(b); |
1da177e4 LT |
78 | } |
79 | ||
80 | typedef struct faulty_conf { | |
81 | int period[Modes]; | |
82 | atomic_t counters[Modes]; | |
83 | sector_t faults[MaxFault]; | |
84 | int modes[MaxFault]; | |
85 | int nfaults; | |
86 | mdk_rdev_t *rdev; | |
87 | } conf_t; | |
88 | ||
89 | static int check_mode(conf_t *conf, int mode) | |
90 | { | |
91 | if (conf->period[mode] == 0 && | |
92 | atomic_read(&conf->counters[mode]) <= 0) | |
93 | return 0; /* no failure, no decrement */ | |
94 | ||
95 | ||
96 | if (atomic_dec_and_test(&conf->counters[mode])) { | |
97 | if (conf->period[mode]) | |
98 | atomic_set(&conf->counters[mode], conf->period[mode]); | |
99 | return 1; | |
100 | } | |
101 | return 0; | |
102 | } | |
103 | ||
104 | static int check_sector(conf_t *conf, sector_t start, sector_t end, int dir) | |
105 | { | |
106 | /* If we find a ReadFixable sector, we fix it ... */ | |
107 | int i; | |
108 | for (i=0; i<conf->nfaults; i++) | |
109 | if (conf->faults[i] >= start && | |
110 | conf->faults[i] < end) { | |
111 | /* found it ... */ | |
112 | switch (conf->modes[i] * 2 + dir) { | |
113 | case WritePersistent*2+WRITE: return 1; | |
114 | case ReadPersistent*2+READ: return 1; | |
115 | case ReadFixable*2+READ: return 1; | |
116 | case ReadFixable*2+WRITE: | |
117 | conf->modes[i] = NoPersist; | |
118 | return 0; | |
119 | case AllPersist*2+READ: | |
120 | case AllPersist*2+WRITE: return 1; | |
121 | default: | |
122 | return 0; | |
123 | } | |
124 | } | |
125 | return 0; | |
126 | } | |
127 | ||
128 | static void add_sector(conf_t *conf, sector_t start, int mode) | |
129 | { | |
130 | int i; | |
131 | int n = conf->nfaults; | |
132 | for (i=0; i<conf->nfaults; i++) | |
133 | if (conf->faults[i] == start) { | |
134 | switch(mode) { | |
135 | case NoPersist: conf->modes[i] = mode; return; | |
136 | case WritePersistent: | |
137 | if (conf->modes[i] == ReadPersistent || | |
138 | conf->modes[i] == ReadFixable) | |
139 | conf->modes[i] = AllPersist; | |
140 | else | |
141 | conf->modes[i] = WritePersistent; | |
142 | return; | |
143 | case ReadPersistent: | |
144 | if (conf->modes[i] == WritePersistent) | |
145 | conf->modes[i] = AllPersist; | |
146 | else | |
147 | conf->modes[i] = ReadPersistent; | |
148 | return; | |
149 | case ReadFixable: | |
150 | if (conf->modes[i] == WritePersistent || | |
151 | conf->modes[i] == ReadPersistent) | |
152 | conf->modes[i] = AllPersist; | |
153 | else | |
154 | conf->modes[i] = ReadFixable; | |
155 | return; | |
156 | } | |
157 | } else if (conf->modes[i] == NoPersist) | |
158 | n = i; | |
159 | ||
160 | if (n >= MaxFault) | |
161 | return; | |
162 | conf->faults[n] = start; | |
163 | conf->modes[n] = mode; | |
164 | if (conf->nfaults == n) | |
165 | conf->nfaults = n+1; | |
166 | } | |
167 | ||
165125e1 | 168 | static int make_request(struct request_queue *q, struct bio *bio) |
1da177e4 LT |
169 | { |
170 | mddev_t *mddev = q->queuedata; | |
171 | conf_t *conf = (conf_t*)mddev->private; | |
172 | int failit = 0; | |
173 | ||
802ba064 | 174 | if (bio_data_dir(bio) == WRITE) { |
1da177e4 LT |
175 | /* write request */ |
176 | if (atomic_read(&conf->counters[WriteAll])) { | |
177 | /* special case - don't decrement, don't generic_make_request, | |
178 | * just fail immediately | |
179 | */ | |
6712ecf8 | 180 | bio_endio(bio, -EIO); |
1da177e4 LT |
181 | return 0; |
182 | } | |
183 | ||
184 | if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9), | |
185 | WRITE)) | |
186 | failit = 1; | |
187 | if (check_mode(conf, WritePersistent)) { | |
188 | add_sector(conf, bio->bi_sector, WritePersistent); | |
189 | failit = 1; | |
190 | } | |
191 | if (check_mode(conf, WriteTransient)) | |
192 | failit = 1; | |
193 | } else { | |
194 | /* read request */ | |
195 | if (check_sector(conf, bio->bi_sector, bio->bi_sector + (bio->bi_size>>9), | |
196 | READ)) | |
197 | failit = 1; | |
198 | if (check_mode(conf, ReadTransient)) | |
199 | failit = 1; | |
200 | if (check_mode(conf, ReadPersistent)) { | |
201 | add_sector(conf, bio->bi_sector, ReadPersistent); | |
202 | failit = 1; | |
203 | } | |
204 | if (check_mode(conf, ReadFixable)) { | |
205 | add_sector(conf, bio->bi_sector, ReadFixable); | |
206 | failit = 1; | |
207 | } | |
208 | } | |
209 | if (failit) { | |
210 | struct bio *b = bio_clone(bio, GFP_NOIO); | |
211 | b->bi_bdev = conf->rdev->bdev; | |
212 | b->bi_private = bio; | |
213 | b->bi_end_io = faulty_fail; | |
214 | generic_make_request(b); | |
215 | return 0; | |
216 | } else { | |
217 | bio->bi_bdev = conf->rdev->bdev; | |
218 | return 1; | |
219 | } | |
220 | } | |
221 | ||
222 | static void status(struct seq_file *seq, mddev_t *mddev) | |
223 | { | |
224 | conf_t *conf = (conf_t*)mddev->private; | |
225 | int n; | |
226 | ||
227 | if ((n=atomic_read(&conf->counters[WriteTransient])) != 0) | |
228 | seq_printf(seq, " WriteTransient=%d(%d)", | |
229 | n, conf->period[WriteTransient]); | |
230 | ||
231 | if ((n=atomic_read(&conf->counters[ReadTransient])) != 0) | |
232 | seq_printf(seq, " ReadTransient=%d(%d)", | |
233 | n, conf->period[ReadTransient]); | |
234 | ||
235 | if ((n=atomic_read(&conf->counters[WritePersistent])) != 0) | |
236 | seq_printf(seq, " WritePersistent=%d(%d)", | |
237 | n, conf->period[WritePersistent]); | |
238 | ||
239 | if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0) | |
240 | seq_printf(seq, " ReadPersistent=%d(%d)", | |
241 | n, conf->period[ReadPersistent]); | |
242 | ||
243 | ||
244 | if ((n=atomic_read(&conf->counters[ReadFixable])) != 0) | |
245 | seq_printf(seq, " ReadFixable=%d(%d)", | |
246 | n, conf->period[ReadFixable]); | |
247 | ||
248 | if ((n=atomic_read(&conf->counters[WriteAll])) != 0) | |
249 | seq_printf(seq, " WriteAll"); | |
250 | ||
251 | seq_printf(seq, " nfaults=%d", conf->nfaults); | |
252 | } | |
253 | ||
254 | ||
255 | static int reconfig(mddev_t *mddev, int layout, int chunk_size) | |
256 | { | |
257 | int mode = layout & ModeMask; | |
258 | int count = layout >> ModeShift; | |
259 | conf_t *conf = mddev->private; | |
260 | ||
261 | if (chunk_size != -1) | |
262 | return -EINVAL; | |
263 | ||
264 | /* new layout */ | |
265 | if (mode == ClearFaults) | |
266 | conf->nfaults = 0; | |
267 | else if (mode == ClearErrors) { | |
268 | int i; | |
269 | for (i=0 ; i < Modes ; i++) { | |
270 | conf->period[i] = 0; | |
271 | atomic_set(&conf->counters[i], 0); | |
272 | } | |
273 | } else if (mode < Modes) { | |
274 | conf->period[mode] = count; | |
275 | if (!count) count++; | |
276 | atomic_set(&conf->counters[mode], count); | |
277 | } else | |
278 | return -EINVAL; | |
279 | mddev->layout = -1; /* makes sure further changes come through */ | |
280 | return 0; | |
281 | } | |
282 | ||
283 | static int run(mddev_t *mddev) | |
284 | { | |
285 | mdk_rdev_t *rdev; | |
286 | struct list_head *tmp; | |
287 | int i; | |
288 | ||
289 | conf_t *conf = kmalloc(sizeof(*conf), GFP_KERNEL); | |
290 | ||
291 | for (i=0; i<Modes; i++) { | |
292 | atomic_set(&conf->counters[i], 0); | |
293 | conf->period[i] = 0; | |
294 | } | |
295 | conf->nfaults = 0; | |
296 | ||
d089c6af | 297 | rdev_for_each(rdev, tmp, mddev) |
1da177e4 LT |
298 | conf->rdev = rdev; |
299 | ||
300 | mddev->array_size = mddev->size; | |
301 | mddev->private = conf; | |
302 | ||
303 | reconfig(mddev, mddev->layout, -1); | |
304 | ||
305 | return 0; | |
306 | } | |
307 | ||
308 | static int stop(mddev_t *mddev) | |
309 | { | |
310 | conf_t *conf = (conf_t *)mddev->private; | |
311 | ||
312 | kfree(conf); | |
313 | mddev->private = NULL; | |
314 | return 0; | |
315 | } | |
316 | ||
2604b703 | 317 | static struct mdk_personality faulty_personality = |
1da177e4 LT |
318 | { |
319 | .name = "faulty", | |
2604b703 | 320 | .level = LEVEL_FAULTY, |
1da177e4 LT |
321 | .owner = THIS_MODULE, |
322 | .make_request = make_request, | |
323 | .run = run, | |
324 | .stop = stop, | |
325 | .status = status, | |
326 | .reconfig = reconfig, | |
327 | }; | |
328 | ||
329 | static int __init raid_init(void) | |
330 | { | |
2604b703 | 331 | return register_md_personality(&faulty_personality); |
1da177e4 LT |
332 | } |
333 | ||
334 | static void raid_exit(void) | |
335 | { | |
2604b703 | 336 | unregister_md_personality(&faulty_personality); |
1da177e4 LT |
337 | } |
338 | ||
339 | module_init(raid_init); | |
340 | module_exit(raid_exit); | |
341 | MODULE_LICENSE("GPL"); | |
342 | MODULE_ALIAS("md-personality-10"); /* faulty */ | |
d9d166c2 | 343 | MODULE_ALIAS("md-faulty"); |
2604b703 | 344 | MODULE_ALIAS("md-level--5"); |