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 recurrence 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/blkdev.h>
66 #include <linux/module.h>
67 #include <linux/raid/md_u.h>
68 #include <linux/slab.h>
69 #include "md.h"
70 #include <linux/seq_file.h>
71
72
faulty_fail(struct bio * bio,int error)73 static void faulty_fail(struct bio *bio, int error)
74 {
75 struct bio *b = bio->bi_private;
76
77 b->bi_size = bio->bi_size;
78 b->bi_sector = bio->bi_sector;
79
80 bio_put(bio);
81
82 bio_io_error(b);
83 }
84
85 struct faulty_conf {
86 int period[Modes];
87 atomic_t counters[Modes];
88 sector_t faults[MaxFault];
89 int modes[MaxFault];
90 int nfaults;
91 struct md_rdev *rdev;
92 };
93
check_mode(struct faulty_conf * conf,int mode)94 static int check_mode(struct faulty_conf *conf, int mode)
95 {
96 if (conf->period[mode] == 0 &&
97 atomic_read(&conf->counters[mode]) <= 0)
98 return 0; /* no failure, no decrement */
99
100
101 if (atomic_dec_and_test(&conf->counters[mode])) {
102 if (conf->period[mode])
103 atomic_set(&conf->counters[mode], conf->period[mode]);
104 return 1;
105 }
106 return 0;
107 }
108
check_sector(struct faulty_conf * conf,sector_t start,sector_t end,int dir)109 static int check_sector(struct faulty_conf *conf, sector_t start, sector_t end, int dir)
110 {
111 /* If we find a ReadFixable sector, we fix it ... */
112 int i;
113 for (i=0; i<conf->nfaults; i++)
114 if (conf->faults[i] >= start &&
115 conf->faults[i] < end) {
116 /* found it ... */
117 switch (conf->modes[i] * 2 + dir) {
118 case WritePersistent*2+WRITE: return 1;
119 case ReadPersistent*2+READ: return 1;
120 case ReadFixable*2+READ: return 1;
121 case ReadFixable*2+WRITE:
122 conf->modes[i] = NoPersist;
123 return 0;
124 case AllPersist*2+READ:
125 case AllPersist*2+WRITE: return 1;
126 default:
127 return 0;
128 }
129 }
130 return 0;
131 }
132
add_sector(struct faulty_conf * conf,sector_t start,int mode)133 static void add_sector(struct faulty_conf *conf, sector_t start, int mode)
134 {
135 int i;
136 int n = conf->nfaults;
137 for (i=0; i<conf->nfaults; i++)
138 if (conf->faults[i] == start) {
139 switch(mode) {
140 case NoPersist: conf->modes[i] = mode; return;
141 case WritePersistent:
142 if (conf->modes[i] == ReadPersistent ||
143 conf->modes[i] == ReadFixable)
144 conf->modes[i] = AllPersist;
145 else
146 conf->modes[i] = WritePersistent;
147 return;
148 case ReadPersistent:
149 if (conf->modes[i] == WritePersistent)
150 conf->modes[i] = AllPersist;
151 else
152 conf->modes[i] = ReadPersistent;
153 return;
154 case ReadFixable:
155 if (conf->modes[i] == WritePersistent ||
156 conf->modes[i] == ReadPersistent)
157 conf->modes[i] = AllPersist;
158 else
159 conf->modes[i] = ReadFixable;
160 return;
161 }
162 } else if (conf->modes[i] == NoPersist)
163 n = i;
164
165 if (n >= MaxFault)
166 return;
167 conf->faults[n] = start;
168 conf->modes[n] = mode;
169 if (conf->nfaults == n)
170 conf->nfaults = n+1;
171 }
172
make_request(struct mddev * mddev,struct bio * bio)173 static void make_request(struct mddev *mddev, struct bio *bio)
174 {
175 struct faulty_conf *conf = mddev->private;
176 int failit = 0;
177
178 if (bio_data_dir(bio) == WRITE) {
179 /* write request */
180 if (atomic_read(&conf->counters[WriteAll])) {
181 /* special case - don't decrement, don't generic_make_request,
182 * just fail immediately
183 */
184 bio_endio(bio, -EIO);
185 return;
186 }
187
188 if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9),
189 WRITE))
190 failit = 1;
191 if (check_mode(conf, WritePersistent)) {
192 add_sector(conf, bio->bi_sector, WritePersistent);
193 failit = 1;
194 }
195 if (check_mode(conf, WriteTransient))
196 failit = 1;
197 } else {
198 /* read request */
199 if (check_sector(conf, bio->bi_sector, bio->bi_sector + (bio->bi_size>>9),
200 READ))
201 failit = 1;
202 if (check_mode(conf, ReadTransient))
203 failit = 1;
204 if (check_mode(conf, ReadPersistent)) {
205 add_sector(conf, bio->bi_sector, ReadPersistent);
206 failit = 1;
207 }
208 if (check_mode(conf, ReadFixable)) {
209 add_sector(conf, bio->bi_sector, ReadFixable);
210 failit = 1;
211 }
212 }
213 if (failit) {
214 struct bio *b = bio_clone_mddev(bio, GFP_NOIO, mddev);
215
216 b->bi_bdev = conf->rdev->bdev;
217 b->bi_private = bio;
218 b->bi_end_io = faulty_fail;
219 bio = b;
220 } else
221 bio->bi_bdev = conf->rdev->bdev;
222
223 generic_make_request(bio);
224 }
225
status(struct seq_file * seq,struct mddev * mddev)226 static void status(struct seq_file *seq, struct mddev *mddev)
227 {
228 struct faulty_conf *conf = mddev->private;
229 int n;
230
231 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
232 seq_printf(seq, " WriteTransient=%d(%d)",
233 n, conf->period[WriteTransient]);
234
235 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
236 seq_printf(seq, " ReadTransient=%d(%d)",
237 n, conf->period[ReadTransient]);
238
239 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
240 seq_printf(seq, " WritePersistent=%d(%d)",
241 n, conf->period[WritePersistent]);
242
243 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
244 seq_printf(seq, " ReadPersistent=%d(%d)",
245 n, conf->period[ReadPersistent]);
246
247
248 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
249 seq_printf(seq, " ReadFixable=%d(%d)",
250 n, conf->period[ReadFixable]);
251
252 if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
253 seq_printf(seq, " WriteAll");
254
255 seq_printf(seq, " nfaults=%d", conf->nfaults);
256 }
257
258
reshape(struct mddev * mddev)259 static int reshape(struct mddev *mddev)
260 {
261 int mode = mddev->new_layout & ModeMask;
262 int count = mddev->new_layout >> ModeShift;
263 struct faulty_conf *conf = mddev->private;
264
265 if (mddev->new_layout < 0)
266 return 0;
267
268 /* new layout */
269 if (mode == ClearFaults)
270 conf->nfaults = 0;
271 else if (mode == ClearErrors) {
272 int i;
273 for (i=0 ; i < Modes ; i++) {
274 conf->period[i] = 0;
275 atomic_set(&conf->counters[i], 0);
276 }
277 } else if (mode < Modes) {
278 conf->period[mode] = count;
279 if (!count) count++;
280 atomic_set(&conf->counters[mode], count);
281 } else
282 return -EINVAL;
283 mddev->new_layout = -1;
284 mddev->layout = -1; /* makes sure further changes come through */
285 return 0;
286 }
287
faulty_size(struct mddev * mddev,sector_t sectors,int raid_disks)288 static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks)
289 {
290 WARN_ONCE(raid_disks,
291 "%s does not support generic reshape\n", __func__);
292
293 if (sectors == 0)
294 return mddev->dev_sectors;
295
296 return sectors;
297 }
298
run(struct mddev * mddev)299 static int run(struct mddev *mddev)
300 {
301 struct md_rdev *rdev;
302 int i;
303 struct faulty_conf *conf;
304
305 if (md_check_no_bitmap(mddev))
306 return -EINVAL;
307
308 conf = kmalloc(sizeof(*conf), GFP_KERNEL);
309 if (!conf)
310 return -ENOMEM;
311
312 for (i=0; i<Modes; i++) {
313 atomic_set(&conf->counters[i], 0);
314 conf->period[i] = 0;
315 }
316 conf->nfaults = 0;
317
318 rdev_for_each(rdev, mddev)
319 conf->rdev = rdev;
320
321 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
322 mddev->private = conf;
323
324 reshape(mddev);
325
326 return 0;
327 }
328
stop(struct mddev * mddev)329 static int stop(struct mddev *mddev)
330 {
331 struct faulty_conf *conf = mddev->private;
332
333 kfree(conf);
334 mddev->private = NULL;
335 return 0;
336 }
337
338 static struct md_personality faulty_personality =
339 {
340 .name = "faulty",
341 .level = LEVEL_FAULTY,
342 .owner = THIS_MODULE,
343 .make_request = make_request,
344 .run = run,
345 .stop = stop,
346 .status = status,
347 .check_reshape = reshape,
348 .size = faulty_size,
349 };
350
raid_init(void)351 static int __init raid_init(void)
352 {
353 return register_md_personality(&faulty_personality);
354 }
355
raid_exit(void)356 static void raid_exit(void)
357 {
358 unregister_md_personality(&faulty_personality);
359 }
360
361 module_init(raid_init);
362 module_exit(raid_exit);
363 MODULE_LICENSE("GPL");
364 MODULE_DESCRIPTION("Fault injection personality for MD");
365 MODULE_ALIAS("md-personality-10"); /* faulty */
366 MODULE_ALIAS("md-faulty");
367 MODULE_ALIAS("md-level--5");
368