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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
NeilBrownbff61972009-03-31 14:33:13 +110065#include <linux/blkdev.h>
66#include <linux/raid/md_u.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090067#include <linux/slab.h>
NeilBrown43b2e5d2009-03-31 14:33:13 +110068#include "md.h"
NeilBrownbff61972009-03-31 14:33:13 +110069#include <linux/seq_file.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
71
NeilBrown6712ecf2007-09-27 12:47:43 +020072static void faulty_fail(struct bio *bio, int error)
Linus Torvalds1da177e2005-04-16 15:20:36 -070073{
74 struct bio *b = bio->bi_private;
75
76 b->bi_size = bio->bi_size;
77 b->bi_sector = bio->bi_sector;
78
NeilBrown6712ecf2007-09-27 12:47:43 +020079 bio_put(bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
NeilBrown6712ecf2007-09-27 12:47:43 +020081 bio_io_error(b);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082}
83
84typedef struct faulty_conf {
85 int period[Modes];
86 atomic_t counters[Modes];
87 sector_t faults[MaxFault];
88 int modes[MaxFault];
89 int nfaults;
90 mdk_rdev_t *rdev;
91} conf_t;
92
93static int check_mode(conf_t *conf, int mode)
94{
95 if (conf->period[mode] == 0 &&
96 atomic_read(&conf->counters[mode]) <= 0)
97 return 0; /* no failure, no decrement */
98
99
100 if (atomic_dec_and_test(&conf->counters[mode])) {
101 if (conf->period[mode])
102 atomic_set(&conf->counters[mode], conf->period[mode]);
103 return 1;
104 }
105 return 0;
106}
107
108static int check_sector(conf_t *conf, sector_t start, sector_t end, int dir)
109{
110 /* If we find a ReadFixable sector, we fix it ... */
111 int i;
112 for (i=0; i<conf->nfaults; i++)
113 if (conf->faults[i] >= start &&
114 conf->faults[i] < end) {
115 /* found it ... */
116 switch (conf->modes[i] * 2 + dir) {
117 case WritePersistent*2+WRITE: return 1;
118 case ReadPersistent*2+READ: return 1;
119 case ReadFixable*2+READ: return 1;
120 case ReadFixable*2+WRITE:
121 conf->modes[i] = NoPersist;
122 return 0;
123 case AllPersist*2+READ:
124 case AllPersist*2+WRITE: return 1;
125 default:
126 return 0;
127 }
128 }
129 return 0;
130}
131
132static void add_sector(conf_t *conf, sector_t start, int mode)
133{
134 int i;
135 int n = conf->nfaults;
136 for (i=0; i<conf->nfaults; i++)
137 if (conf->faults[i] == start) {
138 switch(mode) {
139 case NoPersist: conf->modes[i] = mode; return;
140 case WritePersistent:
141 if (conf->modes[i] == ReadPersistent ||
142 conf->modes[i] == ReadFixable)
143 conf->modes[i] = AllPersist;
144 else
145 conf->modes[i] = WritePersistent;
146 return;
147 case ReadPersistent:
148 if (conf->modes[i] == WritePersistent)
149 conf->modes[i] = AllPersist;
150 else
151 conf->modes[i] = ReadPersistent;
152 return;
153 case ReadFixable:
154 if (conf->modes[i] == WritePersistent ||
155 conf->modes[i] == ReadPersistent)
156 conf->modes[i] = AllPersist;
157 else
158 conf->modes[i] = ReadFixable;
159 return;
160 }
161 } else if (conf->modes[i] == NoPersist)
162 n = i;
163
164 if (n >= MaxFault)
165 return;
166 conf->faults[n] = start;
167 conf->modes[n] = mode;
168 if (conf->nfaults == n)
169 conf->nfaults = n+1;
170}
171
NeilBrown21a52c62010-04-01 15:02:13 +1100172static int make_request(mddev_t *mddev, struct bio *bio)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173{
H Hartley Sweeten7b928132010-03-08 16:02:40 +1100174 conf_t *conf = mddev->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 int failit = 0;
176
NeilBrown802ba062006-12-13 00:34:13 -0800177 if (bio_data_dir(bio) == WRITE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 /* write request */
179 if (atomic_read(&conf->counters[WriteAll])) {
180 /* special case - don't decrement, don't generic_make_request,
181 * just fail immediately
182 */
NeilBrown6712ecf2007-09-27 12:47:43 +0200183 bio_endio(bio, -EIO);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 return 0;
185 }
186
187 if (check_sector(conf, bio->bi_sector, bio->bi_sector+(bio->bi_size>>9),
188 WRITE))
189 failit = 1;
190 if (check_mode(conf, WritePersistent)) {
191 add_sector(conf, bio->bi_sector, WritePersistent);
192 failit = 1;
193 }
194 if (check_mode(conf, WriteTransient))
195 failit = 1;
196 } else {
197 /* read request */
198 if (check_sector(conf, bio->bi_sector, bio->bi_sector + (bio->bi_size>>9),
199 READ))
200 failit = 1;
201 if (check_mode(conf, ReadTransient))
202 failit = 1;
203 if (check_mode(conf, ReadPersistent)) {
204 add_sector(conf, bio->bi_sector, ReadPersistent);
205 failit = 1;
206 }
207 if (check_mode(conf, ReadFixable)) {
208 add_sector(conf, bio->bi_sector, ReadFixable);
209 failit = 1;
210 }
211 }
212 if (failit) {
213 struct bio *b = bio_clone(bio, GFP_NOIO);
214 b->bi_bdev = conf->rdev->bdev;
215 b->bi_private = bio;
216 b->bi_end_io = faulty_fail;
217 generic_make_request(b);
218 return 0;
219 } else {
220 bio->bi_bdev = conf->rdev->bdev;
221 return 1;
222 }
223}
224
225static void status(struct seq_file *seq, mddev_t *mddev)
226{
H Hartley Sweeten7b928132010-03-08 16:02:40 +1100227 conf_t *conf = mddev->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 int n;
229
230 if ((n=atomic_read(&conf->counters[WriteTransient])) != 0)
231 seq_printf(seq, " WriteTransient=%d(%d)",
232 n, conf->period[WriteTransient]);
233
234 if ((n=atomic_read(&conf->counters[ReadTransient])) != 0)
235 seq_printf(seq, " ReadTransient=%d(%d)",
236 n, conf->period[ReadTransient]);
237
238 if ((n=atomic_read(&conf->counters[WritePersistent])) != 0)
239 seq_printf(seq, " WritePersistent=%d(%d)",
240 n, conf->period[WritePersistent]);
241
242 if ((n=atomic_read(&conf->counters[ReadPersistent])) != 0)
243 seq_printf(seq, " ReadPersistent=%d(%d)",
244 n, conf->period[ReadPersistent]);
245
246
247 if ((n=atomic_read(&conf->counters[ReadFixable])) != 0)
248 seq_printf(seq, " ReadFixable=%d(%d)",
249 n, conf->period[ReadFixable]);
250
251 if ((n=atomic_read(&conf->counters[WriteAll])) != 0)
252 seq_printf(seq, " WriteAll");
253
254 seq_printf(seq, " nfaults=%d", conf->nfaults);
255}
256
257
NeilBrown50ac1682009-06-18 08:47:55 +1000258static int reshape(mddev_t *mddev)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259{
NeilBrown597a7112009-06-18 08:47:42 +1000260 int mode = mddev->new_layout & ModeMask;
261 int count = mddev->new_layout >> ModeShift;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 conf_t *conf = mddev->private;
263
NeilBrown597a7112009-06-18 08:47:42 +1000264 if (mddev->new_layout < 0)
265 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266
267 /* new layout */
268 if (mode == ClearFaults)
269 conf->nfaults = 0;
270 else if (mode == ClearErrors) {
271 int i;
272 for (i=0 ; i < Modes ; i++) {
273 conf->period[i] = 0;
274 atomic_set(&conf->counters[i], 0);
275 }
276 } else if (mode < Modes) {
277 conf->period[mode] = count;
278 if (!count) count++;
279 atomic_set(&conf->counters[mode], count);
280 } else
281 return -EINVAL;
NeilBrown597a7112009-06-18 08:47:42 +1000282 mddev->new_layout = -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700283 mddev->layout = -1; /* makes sure further changes come through */
284 return 0;
285}
286
Dan Williams80c3a6c2009-03-17 18:10:40 -0700287static sector_t faulty_size(mddev_t *mddev, sector_t sectors, int raid_disks)
288{
289 WARN_ONCE(raid_disks,
290 "%s does not support generic reshape\n", __func__);
291
292 if (sectors == 0)
293 return mddev->dev_sectors;
294
295 return sectors;
296}
297
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298static int run(mddev_t *mddev)
299{
300 mdk_rdev_t *rdev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 int i;
Andre Noll0894cc32009-06-18 08:49:23 +1000302 conf_t *conf;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303
Andre Noll0894cc32009-06-18 08:49:23 +1000304 if (md_check_no_bitmap(mddev))
305 return -EINVAL;
306
307 conf = kmalloc(sizeof(*conf), GFP_KERNEL);
Sven Wegener08ff39f2008-10-16 14:16:53 +1100308 if (!conf)
309 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310
311 for (i=0; i<Modes; i++) {
312 atomic_set(&conf->counters[i], 0);
313 conf->period[i] = 0;
314 }
315 conf->nfaults = 0;
316
Cheng Renquan159ec1f2009-01-09 08:31:08 +1100317 list_for_each_entry(rdev, &mddev->disks, same_set)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 conf->rdev = rdev;
319
Dan Williams1f403622009-03-31 14:59:03 +1100320 md_set_array_sectors(mddev, faulty_size(mddev, 0, 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321 mddev->private = conf;
322
NeilBrown50ac1682009-06-18 08:47:55 +1000323 reshape(mddev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700324
325 return 0;
326}
327
328static int stop(mddev_t *mddev)
329{
H Hartley Sweeten7b928132010-03-08 16:02:40 +1100330 conf_t *conf = mddev->private;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331
332 kfree(conf);
333 mddev->private = NULL;
334 return 0;
335}
336
NeilBrown2604b702006-01-06 00:20:36 -0800337static struct mdk_personality faulty_personality =
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338{
339 .name = "faulty",
NeilBrown2604b702006-01-06 00:20:36 -0800340 .level = LEVEL_FAULTY,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 .owner = THIS_MODULE,
342 .make_request = make_request,
343 .run = run,
344 .stop = stop,
345 .status = status,
NeilBrown50ac1682009-06-18 08:47:55 +1000346 .check_reshape = reshape,
Dan Williams80c3a6c2009-03-17 18:10:40 -0700347 .size = faulty_size,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348};
349
350static int __init raid_init(void)
351{
NeilBrown2604b702006-01-06 00:20:36 -0800352 return register_md_personality(&faulty_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353}
354
355static void raid_exit(void)
356{
NeilBrown2604b702006-01-06 00:20:36 -0800357 unregister_md_personality(&faulty_personality);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700358}
359
360module_init(raid_init);
361module_exit(raid_exit);
362MODULE_LICENSE("GPL");
NeilBrown0efb9e62009-12-14 12:49:58 +1100363MODULE_DESCRIPTION("Fault injection personality for MD");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364MODULE_ALIAS("md-personality-10"); /* faulty */
NeilBrownd9d166c2006-01-06 00:20:51 -0800365MODULE_ALIAS("md-faulty");
NeilBrown2604b702006-01-06 00:20:36 -0800366MODULE_ALIAS("md-level--5");