1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * faulty.c : Multiple Devices driver for Linux
4 *
5 * Copyright (C) 2004 Neil Brown
6 *
7 * fautly-device-simulator personality for md
8 */
9
10
11 /*
12 * The "faulty" personality causes some requests to fail.
13 *
14 * Possible failure modes are:
15 * reads fail "randomly" but succeed on retry
16 * writes fail "randomly" but succeed on retry
17 * reads for some address fail and then persist until a write
18 * reads for some address fail and then persist irrespective of write
19 * writes for some address fail and persist
20 * all writes fail
21 *
22 * Different modes can be active at a time, but only
23 * one can be set at array creation. Others can be added later.
24 * A mode can be one-shot or recurrent with the recurrence being
25 * once in every N requests.
26 * The bottom 5 bits of the "layout" indicate the mode. The
27 * remainder indicate a period, or 0 for one-shot.
28 *
29 * There is an implementation limit on the number of concurrently
30 * persisting-faulty blocks. When a new fault is requested that would
31 * exceed the limit, it is ignored.
32 * All current faults can be clear using a layout of "0".
33 *
34 * Requests are always sent to the device. If they are to fail,
35 * we clone the bio and insert a new b_end_io into the chain.
36 */
37
38 #define WriteTransient 0
39 #define ReadTransient 1
40 #define WritePersistent 2
41 #define ReadPersistent 3
42 #define WriteAll 4 /* doesn't go to device */
43 #define ReadFixable 5
44 #define Modes 6
45
46 #define ClearErrors 31
47 #define ClearFaults 30
48
49 #define AllPersist 100 /* internal use only */
50 #define NoPersist 101
51
52 #define ModeMask 0x1f
53 #define ModeShift 5
54
55 #define MaxFault 50
56 #include <linux/blkdev.h>
57 #include <linux/module.h>
58 #include <linux/raid/md_u.h>
59 #include <linux/slab.h>
60 #include "md.h"
61 #include <linux/seq_file.h>
62
63
faulty_fail(struct bio * bio)64 static void faulty_fail(struct bio *bio)
65 {
66 struct bio *b = bio->bi_private;
67
68 b->bi_iter.bi_size = bio->bi_iter.bi_size;
69 b->bi_iter.bi_sector = bio->bi_iter.bi_sector;
70
71 bio_put(bio);
72
73 bio_io_error(b);
74 }
75
76 struct faulty_conf {
77 int period[Modes];
78 atomic_t counters[Modes];
79 sector_t faults[MaxFault];
80 int modes[MaxFault];
81 int nfaults;
82 struct md_rdev *rdev;
83 };
84
check_mode(struct faulty_conf * conf,int mode)85 static int check_mode(struct faulty_conf *conf, int mode)
86 {
87 if (conf->period[mode] == 0 &&
88 atomic_read(&conf->counters[mode]) <= 0)
89 return 0; /* no failure, no decrement */
90
91
92 if (atomic_dec_and_test(&conf->counters[mode])) {
93 if (conf->period[mode])
94 atomic_set(&conf->counters[mode], conf->period[mode]);
95 return 1;
96 }
97 return 0;
98 }
99
check_sector(struct faulty_conf * conf,sector_t start,sector_t end,int dir)100 static int check_sector(struct faulty_conf *conf, sector_t start, sector_t end, int dir)
101 {
102 /* If we find a ReadFixable sector, we fix it ... */
103 int i;
104 for (i=0; i<conf->nfaults; i++)
105 if (conf->faults[i] >= start &&
106 conf->faults[i] < end) {
107 /* found it ... */
108 switch (conf->modes[i] * 2 + dir) {
109 case WritePersistent*2+WRITE: return 1;
110 case ReadPersistent*2+READ: return 1;
111 case ReadFixable*2+READ: return 1;
112 case ReadFixable*2+WRITE:
113 conf->modes[i] = NoPersist;
114 return 0;
115 case AllPersist*2+READ:
116 case AllPersist*2+WRITE: return 1;
117 default:
118 return 0;
119 }
120 }
121 return 0;
122 }
123
add_sector(struct faulty_conf * conf,sector_t start,int mode)124 static void add_sector(struct faulty_conf *conf, sector_t start, int mode)
125 {
126 int i;
127 int n = conf->nfaults;
128 for (i=0; i<conf->nfaults; i++)
129 if (conf->faults[i] == start) {
130 switch(mode) {
131 case NoPersist: conf->modes[i] = mode; return;
132 case WritePersistent:
133 if (conf->modes[i] == ReadPersistent ||
134 conf->modes[i] == ReadFixable)
135 conf->modes[i] = AllPersist;
136 else
137 conf->modes[i] = WritePersistent;
138 return;
139 case ReadPersistent:
140 if (conf->modes[i] == WritePersistent)
141 conf->modes[i] = AllPersist;
142 else
143 conf->modes[i] = ReadPersistent;
144 return;
145 case ReadFixable:
146 if (conf->modes[i] == WritePersistent ||
147 conf->modes[i] == ReadPersistent)
148 conf->modes[i] = AllPersist;
149 else
150 conf->modes[i] = ReadFixable;
151 return;
152 }
153 } else if (conf->modes[i] == NoPersist)
154 n = i;
155
156 if (n >= MaxFault)
157 return;
158 conf->faults[n] = start;
159 conf->modes[n] = mode;
160 if (conf->nfaults == n)
161 conf->nfaults = n+1;
162 }
163
faulty_make_request(struct mddev * mddev,struct bio * bio)164 static bool faulty_make_request(struct mddev *mddev, struct bio *bio)
165 {
166 struct faulty_conf *conf = mddev->private;
167 int failit = 0;
168
169 if (bio_data_dir(bio) == WRITE) {
170 /* write request */
171 if (atomic_read(&conf->counters[WriteAll])) {
172 /* special case - don't decrement, don't submit_bio_noacct,
173 * just fail immediately
174 */
175 bio_io_error(bio);
176 return true;
177 }
178
179 if (check_sector(conf, bio->bi_iter.bi_sector,
180 bio_end_sector(bio), WRITE))
181 failit = 1;
182 if (check_mode(conf, WritePersistent)) {
183 add_sector(conf, bio->bi_iter.bi_sector,
184 WritePersistent);
185 failit = 1;
186 }
187 if (check_mode(conf, WriteTransient))
188 failit = 1;
189 } else {
190 /* read request */
191 if (check_sector(conf, bio->bi_iter.bi_sector,
192 bio_end_sector(bio), READ))
193 failit = 1;
194 if (check_mode(conf, ReadTransient))
195 failit = 1;
196 if (check_mode(conf, ReadPersistent)) {
197 add_sector(conf, bio->bi_iter.bi_sector,
198 ReadPersistent);
199 failit = 1;
200 }
201 if (check_mode(conf, ReadFixable)) {
202 add_sector(conf, bio->bi_iter.bi_sector,
203 ReadFixable);
204 failit = 1;
205 }
206 }
207 if (failit) {
208 struct bio *b = bio_clone_fast(bio, GFP_NOIO, &mddev->bio_set);
209
210 bio_set_dev(b, conf->rdev->bdev);
211 b->bi_private = bio;
212 b->bi_end_io = faulty_fail;
213 bio = b;
214 } else
215 bio_set_dev(bio, conf->rdev->bdev);
216
217 submit_bio_noacct(bio);
218 return true;
219 }
220
faulty_status(struct seq_file * seq,struct mddev * mddev)221 static void faulty_status(struct seq_file *seq, struct mddev *mddev)
222 {
223 struct faulty_conf *conf = mddev->private;
224 int n;
225
226 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
227 seq_printf(seq, " WriteTransient=%d(%d)",
228 n, conf->period[WriteTransient]);
229
230 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
231 seq_printf(seq, " ReadTransient=%d(%d)",
232 n, conf->period[ReadTransient]);
233
234 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
235 seq_printf(seq, " WritePersistent=%d(%d)",
236 n, conf->period[WritePersistent]);
237
238 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
239 seq_printf(seq, " ReadPersistent=%d(%d)",
240 n, conf->period[ReadPersistent]);
241
242
243 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
244 seq_printf(seq, " ReadFixable=%d(%d)",
245 n, conf->period[ReadFixable]);
246
247 if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
248 seq_printf(seq, " WriteAll");
249
250 seq_printf(seq, " nfaults=%d", conf->nfaults);
251 }
252
253
faulty_reshape(struct mddev * mddev)254 static int faulty_reshape(struct mddev *mddev)
255 {
256 int mode = mddev->new_layout & ModeMask;
257 int count = mddev->new_layout >> ModeShift;
258 struct faulty_conf *conf = mddev->private;
259
260 if (mddev->new_layout < 0)
261 return 0;
262
263 /* new layout */
264 if (mode == ClearFaults)
265 conf->nfaults = 0;
266 else if (mode == ClearErrors) {
267 int i;
268 for (i=0 ; i < Modes ; i++) {
269 conf->period[i] = 0;
270 atomic_set(&conf->counters[i], 0);
271 }
272 } else if (mode < Modes) {
273 conf->period[mode] = count;
274 if (!count) count++;
275 atomic_set(&conf->counters[mode], count);
276 } else
277 return -EINVAL;
278 mddev->new_layout = -1;
279 mddev->layout = -1; /* makes sure further changes come through */
280 return 0;
281 }
282
faulty_size(struct mddev * mddev,sector_t sectors,int raid_disks)283 static sector_t faulty_size(struct mddev *mddev, sector_t sectors, int raid_disks)
284 {
285 WARN_ONCE(raid_disks,
286 "%s does not support generic reshape\n", __func__);
287
288 if (sectors == 0)
289 return mddev->dev_sectors;
290
291 return sectors;
292 }
293
faulty_run(struct mddev * mddev)294 static int faulty_run(struct mddev *mddev)
295 {
296 struct md_rdev *rdev;
297 int i;
298 struct faulty_conf *conf;
299
300 if (md_check_no_bitmap(mddev))
301 return -EINVAL;
302
303 conf = kmalloc(sizeof(*conf), GFP_KERNEL);
304 if (!conf)
305 return -ENOMEM;
306
307 for (i=0; i<Modes; i++) {
308 atomic_set(&conf->counters[i], 0);
309 conf->period[i] = 0;
310 }
311 conf->nfaults = 0;
312
313 rdev_for_each(rdev, mddev) {
314 conf->rdev = rdev;
315 disk_stack_limits(mddev->gendisk, rdev->bdev,
316 rdev->data_offset << 9);
317 }
318
319 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
320 mddev->private = conf;
321
322 faulty_reshape(mddev);
323
324 return 0;
325 }
326
faulty_free(struct mddev * mddev,void * priv)327 static void faulty_free(struct mddev *mddev, void *priv)
328 {
329 struct faulty_conf *conf = priv;
330
331 kfree(conf);
332 }
333
334 static struct md_personality faulty_personality =
335 {
336 .name = "faulty",
337 .level = LEVEL_FAULTY,
338 .owner = THIS_MODULE,
339 .make_request = faulty_make_request,
340 .run = faulty_run,
341 .free = faulty_free,
342 .status = faulty_status,
343 .check_reshape = faulty_reshape,
344 .size = faulty_size,
345 };
346
raid_init(void)347 static int __init raid_init(void)
348 {
349 return register_md_personality(&faulty_personality);
350 }
351
raid_exit(void)352 static void raid_exit(void)
353 {
354 unregister_md_personality(&faulty_personality);
355 }
356
357 module_init(raid_init);
358 module_exit(raid_exit);
359 MODULE_LICENSE("GPL");
360 MODULE_DESCRIPTION("Fault injection personality for MD");
361 MODULE_ALIAS("md-personality-10"); /* faulty */
362 MODULE_ALIAS("md-faulty");
363 MODULE_ALIAS("md-level--5");
364
