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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
73static void faulty_fail(struct bio *bio)
74{
75 struct bio *b = bio->bi_private;
76
77 b->bi_iter.bi_size = bio->bi_iter.bi_size;
78 b->bi_iter.bi_sector = bio->bi_iter.bi_sector;
79
80 bio_put(bio);
81
82 bio_io_error(b);
83}
84
85struct 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
94static 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
109static 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
133static 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
173static void faulty_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_io_error(bio);
185 return;
186 }
187
188 if (check_sector(conf, bio->bi_iter.bi_sector,
189 bio_end_sector(bio), WRITE))
190 failit = 1;
191 if (check_mode(conf, WritePersistent)) {
192 add_sector(conf, bio->bi_iter.bi_sector,
193 WritePersistent);
194 failit = 1;
195 }
196 if (check_mode(conf, WriteTransient))
197 failit = 1;
198 } else {
199 /* read request */
200 if (check_sector(conf, bio->bi_iter.bi_sector,
201 bio_end_sector(bio), READ))
202 failit = 1;
203 if (check_mode(conf, ReadTransient))
204 failit = 1;
205 if (check_mode(conf, ReadPersistent)) {
206 add_sector(conf, bio->bi_iter.bi_sector,
207 ReadPersistent);
208 failit = 1;
209 }
210 if (check_mode(conf, ReadFixable)) {
211 add_sector(conf, bio->bi_iter.bi_sector,
212 ReadFixable);
213 failit = 1;
214 }
215 }
216 if (failit) {
217 struct bio *b = bio_clone_mddev(bio, GFP_NOIO, mddev);
218
219 b->bi_bdev = conf->rdev->bdev;
220 b->bi_private = bio;
221 b->bi_end_io = faulty_fail;
222 bio = b;
223 } else
224 bio->bi_bdev = conf->rdev->bdev;
225
226 generic_make_request(bio);
227}
228
229static void faulty_status(struct seq_file *seq, struct mddev *mddev)
230{
231 struct faulty_conf *conf = mddev->private;
232 int n;
233
234 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
235 seq_printf(seq, " WriteTransient=%d(%d)",
236 n, conf->period[WriteTransient]);
237
238 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
239 seq_printf(seq, " ReadTransient=%d(%d)",
240 n, conf->period[ReadTransient]);
241
242 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
243 seq_printf(seq, " WritePersistent=%d(%d)",
244 n, conf->period[WritePersistent]);
245
246 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
247 seq_printf(seq, " ReadPersistent=%d(%d)",
248 n, conf->period[ReadPersistent]);
249
250
251 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
252 seq_printf(seq, " ReadFixable=%d(%d)",
253 n, conf->period[ReadFixable]);
254
255 if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
256 seq_printf(seq, " WriteAll");
257
258 seq_printf(seq, " nfaults=%d", conf->nfaults);
259}
260
261
262static int faulty_reshape(struct mddev *mddev)
263{
264 int mode = mddev->new_layout & ModeMask;
265 int count = mddev->new_layout >> ModeShift;
266 struct faulty_conf *conf = mddev->private;
267
268 if (mddev->new_layout < 0)
269 return 0;
270
271 /* new layout */
272 if (mode == ClearFaults)
273 conf->nfaults = 0;
274 else if (mode == ClearErrors) {
275 int i;
276 for (i=0 ; i < Modes ; i++) {
277 conf->period[i] = 0;
278 atomic_set(&conf->counters[i], 0);
279 }
280 } else if (mode < Modes) {
281 conf->period[mode] = count;
282 if (!count) count++;
283 atomic_set(&conf->counters[mode], count);
284 } else
285 return -EINVAL;
286 mddev->new_layout = -1;
287 mddev->layout = -1; /* makes sure further changes come through */
288 return 0;
289}
290
291static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks)
292{
293 WARN_ONCE(raid_disks,
294 "%s does not support generic reshape\n", __func__);
295
296 if (sectors == 0)
297 return mddev->dev_sectors;
298
299 return sectors;
300}
301
302static int faulty_run(struct mddev *mddev)
303{
304 struct md_rdev *rdev;
305 int i;
306 struct faulty_conf *conf;
307
308 if (md_check_no_bitmap(mddev))
309 return -EINVAL;
310
311 conf = kmalloc(sizeof(*conf), GFP_KERNEL);
312 if (!conf)
313 return -ENOMEM;
314
315 for (i=0; i<Modes; i++) {
316 atomic_set(&conf->counters[i], 0);
317 conf->period[i] = 0;
318 }
319 conf->nfaults = 0;
320
321 rdev_for_each(rdev, mddev) {
322 conf->rdev = rdev;
323 disk_stack_limits(mddev->gendisk, rdev->bdev,
324 rdev->data_offset << 9);
325 }
326
327 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
328 mddev->private = conf;
329
330 faulty_reshape(mddev);
331
332 return 0;
333}
334
335static void faulty_free(struct mddev *mddev, void *priv)
336{
337 struct faulty_conf *conf = priv;
338
339 kfree(conf);
340}
341
342static struct md_personality faulty_personality =
343{
344 .name = "faulty",
345 .level = LEVEL_FAULTY,
346 .owner = THIS_MODULE,
347 .make_request = faulty_make_request,
348 .run = faulty_run,
349 .free = faulty_free,
350 .status = faulty_status,
351 .check_reshape = faulty_reshape,
352 .size = faulty_size,
353};
354
355static int __init raid_init(void)
356{
357 return register_md_personality(&faulty_personality);
358}
359
360static void raid_exit(void)
361{
362 unregister_md_personality(&faulty_personality);
363}
364
365module_init(raid_init);
366module_exit(raid_exit);
367MODULE_LICENSE("GPL");
368MODULE_DESCRIPTION("Fault injection personality for MD");
369MODULE_ALIAS("md-personality-10"); /* faulty */
370MODULE_ALIAS("md-faulty");
371MODULE_ALIAS("md-level--5");