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1/*
2 * Copyright (C) 2003 Sistina Software (UK) Limited.
3 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include <linux/device-mapper.h>
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/blkdev.h>
13#include <linux/bio.h>
14#include <linux/slab.h>
15
16#define DM_MSG_PREFIX "flakey"
17
18#define all_corrupt_bio_flags_match(bio, fc) \
19 (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
20
21/*
22 * Flakey: Used for testing only, simulates intermittent,
23 * catastrophic device failure.
24 */
25struct flakey_c {
26 struct dm_dev *dev;
27 unsigned long start_time;
28 sector_t start;
29 unsigned up_interval;
30 unsigned down_interval;
31 unsigned long flags;
32 unsigned corrupt_bio_byte;
33 unsigned corrupt_bio_rw;
34 unsigned corrupt_bio_value;
35 unsigned corrupt_bio_flags;
36};
37
38enum feature_flag_bits {
39 DROP_WRITES,
40 ERROR_WRITES
41};
42
43struct per_bio_data {
44 bool bio_submitted;
45};
46
47static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
48 struct dm_target *ti)
49{
50 int r;
51 unsigned argc;
52 const char *arg_name;
53
54 static const struct dm_arg _args[] = {
55 {0, 6, "Invalid number of feature args"},
56 {1, UINT_MAX, "Invalid corrupt bio byte"},
57 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
58 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
59 };
60
61 /* No feature arguments supplied. */
62 if (!as->argc)
63 return 0;
64
65 r = dm_read_arg_group(_args, as, &argc, &ti->error);
66 if (r)
67 return r;
68
69 while (argc) {
70 arg_name = dm_shift_arg(as);
71 argc--;
72
73 if (!arg_name) {
74 ti->error = "Insufficient feature arguments";
75 return -EINVAL;
76 }
77
78 /*
79 * drop_writes
80 */
81 if (!strcasecmp(arg_name, "drop_writes")) {
82 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
83 ti->error = "Feature drop_writes duplicated";
84 return -EINVAL;
85 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
86 ti->error = "Feature drop_writes conflicts with feature error_writes";
87 return -EINVAL;
88 }
89
90 continue;
91 }
92
93 /*
94 * error_writes
95 */
96 if (!strcasecmp(arg_name, "error_writes")) {
97 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
98 ti->error = "Feature error_writes duplicated";
99 return -EINVAL;
100
101 } else if (test_bit(DROP_WRITES, &fc->flags)) {
102 ti->error = "Feature error_writes conflicts with feature drop_writes";
103 return -EINVAL;
104 }
105
106 continue;
107 }
108
109 /*
110 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
111 */
112 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
113 if (!argc) {
114 ti->error = "Feature corrupt_bio_byte requires parameters";
115 return -EINVAL;
116 }
117
118 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
119 if (r)
120 return r;
121 argc--;
122
123 /*
124 * Direction r or w?
125 */
126 arg_name = dm_shift_arg(as);
127 if (!strcasecmp(arg_name, "w"))
128 fc->corrupt_bio_rw = WRITE;
129 else if (!strcasecmp(arg_name, "r"))
130 fc->corrupt_bio_rw = READ;
131 else {
132 ti->error = "Invalid corrupt bio direction (r or w)";
133 return -EINVAL;
134 }
135 argc--;
136
137 /*
138 * Value of byte (0-255) to write in place of correct one.
139 */
140 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
141 if (r)
142 return r;
143 argc--;
144
145 /*
146 * Only corrupt bios with these flags set.
147 */
148 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
149 if (r)
150 return r;
151 argc--;
152
153 continue;
154 }
155
156 ti->error = "Unrecognised flakey feature requested";
157 return -EINVAL;
158 }
159
160 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
161 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
162 return -EINVAL;
163
164 } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
165 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
166 return -EINVAL;
167 }
168
169 return 0;
170}
171
172/*
173 * Construct a flakey mapping:
174 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
175 *
176 * Feature args:
177 * [drop_writes]
178 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
179 *
180 * Nth_byte starts from 1 for the first byte.
181 * Direction is r for READ or w for WRITE.
182 * bio_flags is ignored if 0.
183 */
184static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
185{
186 static const struct dm_arg _args[] = {
187 {0, UINT_MAX, "Invalid up interval"},
188 {0, UINT_MAX, "Invalid down interval"},
189 };
190
191 int r;
192 struct flakey_c *fc;
193 unsigned long long tmpll;
194 struct dm_arg_set as;
195 const char *devname;
196 char dummy;
197
198 as.argc = argc;
199 as.argv = argv;
200
201 if (argc < 4) {
202 ti->error = "Invalid argument count";
203 return -EINVAL;
204 }
205
206 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
207 if (!fc) {
208 ti->error = "Cannot allocate context";
209 return -ENOMEM;
210 }
211 fc->start_time = jiffies;
212
213 devname = dm_shift_arg(&as);
214
215 r = -EINVAL;
216 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
217 ti->error = "Invalid device sector";
218 goto bad;
219 }
220 fc->start = tmpll;
221
222 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
223 if (r)
224 goto bad;
225
226 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
227 if (r)
228 goto bad;
229
230 if (!(fc->up_interval + fc->down_interval)) {
231 ti->error = "Total (up + down) interval is zero";
232 r = -EINVAL;
233 goto bad;
234 }
235
236 if (fc->up_interval + fc->down_interval < fc->up_interval) {
237 ti->error = "Interval overflow";
238 r = -EINVAL;
239 goto bad;
240 }
241
242 r = parse_features(&as, fc, ti);
243 if (r)
244 goto bad;
245
246 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
247 if (r) {
248 ti->error = "Device lookup failed";
249 goto bad;
250 }
251
252 ti->num_flush_bios = 1;
253 ti->num_discard_bios = 1;
254 ti->per_io_data_size = sizeof(struct per_bio_data);
255 ti->private = fc;
256 return 0;
257
258bad:
259 kfree(fc);
260 return r;
261}
262
263static void flakey_dtr(struct dm_target *ti)
264{
265 struct flakey_c *fc = ti->private;
266
267 dm_put_device(ti, fc->dev);
268 kfree(fc);
269}
270
271static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
272{
273 struct flakey_c *fc = ti->private;
274
275 return fc->start + dm_target_offset(ti, bi_sector);
276}
277
278static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
279{
280 struct flakey_c *fc = ti->private;
281
282 bio_set_dev(bio, fc->dev->bdev);
283 if (bio_sectors(bio) || op_is_zone_mgmt(bio_op(bio)))
284 bio->bi_iter.bi_sector =
285 flakey_map_sector(ti, bio->bi_iter.bi_sector);
286}
287
288static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
289{
290 unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
291
292 struct bvec_iter iter;
293 struct bio_vec bvec;
294
295 if (!bio_has_data(bio))
296 return;
297
298 /*
299 * Overwrite the Nth byte of the bio's data, on whichever page
300 * it falls.
301 */
302 bio_for_each_segment(bvec, bio, iter) {
303 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
304 char *segment = (page_address(bio_iter_page(bio, iter))
305 + bio_iter_offset(bio, iter));
306 segment[corrupt_bio_byte] = fc->corrupt_bio_value;
307 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
308 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
309 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
310 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
311 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
312 break;
313 }
314 corrupt_bio_byte -= bio_iter_len(bio, iter);
315 }
316}
317
318static int flakey_map(struct dm_target *ti, struct bio *bio)
319{
320 struct flakey_c *fc = ti->private;
321 unsigned elapsed;
322 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
323 pb->bio_submitted = false;
324
325 if (op_is_zone_mgmt(bio_op(bio)))
326 goto map_bio;
327
328 /* Are we alive ? */
329 elapsed = (jiffies - fc->start_time) / HZ;
330 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
331 /*
332 * Flag this bio as submitted while down.
333 */
334 pb->bio_submitted = true;
335
336 /*
337 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
338 * Otherwise, flakey_end_io() will decide if the reads should be modified.
339 */
340 if (bio_data_dir(bio) == READ) {
341 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
342 !test_bit(ERROR_WRITES, &fc->flags))
343 return DM_MAPIO_KILL;
344 goto map_bio;
345 }
346
347 /*
348 * Drop or error writes?
349 */
350 if (test_bit(DROP_WRITES, &fc->flags)) {
351 bio_endio(bio);
352 return DM_MAPIO_SUBMITTED;
353 }
354 else if (test_bit(ERROR_WRITES, &fc->flags)) {
355 bio_io_error(bio);
356 return DM_MAPIO_SUBMITTED;
357 }
358
359 /*
360 * Corrupt matching writes.
361 */
362 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
363 if (all_corrupt_bio_flags_match(bio, fc))
364 corrupt_bio_data(bio, fc);
365 goto map_bio;
366 }
367
368 /*
369 * By default, error all I/O.
370 */
371 return DM_MAPIO_KILL;
372 }
373
374map_bio:
375 flakey_map_bio(ti, bio);
376
377 return DM_MAPIO_REMAPPED;
378}
379
380static int flakey_end_io(struct dm_target *ti, struct bio *bio,
381 blk_status_t *error)
382{
383 struct flakey_c *fc = ti->private;
384 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
385
386 if (op_is_zone_mgmt(bio_op(bio)))
387 return DM_ENDIO_DONE;
388
389 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
390 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
391 all_corrupt_bio_flags_match(bio, fc)) {
392 /*
393 * Corrupt successful matching READs while in down state.
394 */
395 corrupt_bio_data(bio, fc);
396
397 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
398 !test_bit(ERROR_WRITES, &fc->flags)) {
399 /*
400 * Error read during the down_interval if drop_writes
401 * and error_writes were not configured.
402 */
403 *error = BLK_STS_IOERR;
404 }
405 }
406
407 return DM_ENDIO_DONE;
408}
409
410static void flakey_status(struct dm_target *ti, status_type_t type,
411 unsigned status_flags, char *result, unsigned maxlen)
412{
413 unsigned sz = 0;
414 struct flakey_c *fc = ti->private;
415 unsigned drop_writes, error_writes;
416
417 switch (type) {
418 case STATUSTYPE_INFO:
419 result[0] = '\0';
420 break;
421
422 case STATUSTYPE_TABLE:
423 DMEMIT("%s %llu %u %u ", fc->dev->name,
424 (unsigned long long)fc->start, fc->up_interval,
425 fc->down_interval);
426
427 drop_writes = test_bit(DROP_WRITES, &fc->flags);
428 error_writes = test_bit(ERROR_WRITES, &fc->flags);
429 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
430
431 if (drop_writes)
432 DMEMIT("drop_writes ");
433 else if (error_writes)
434 DMEMIT("error_writes ");
435
436 if (fc->corrupt_bio_byte)
437 DMEMIT("corrupt_bio_byte %u %c %u %u ",
438 fc->corrupt_bio_byte,
439 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
440 fc->corrupt_bio_value, fc->corrupt_bio_flags);
441
442 break;
443 }
444}
445
446static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
447{
448 struct flakey_c *fc = ti->private;
449
450 *bdev = fc->dev->bdev;
451
452 /*
453 * Only pass ioctls through if the device sizes match exactly.
454 */
455 if (fc->start ||
456 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
457 return 1;
458 return 0;
459}
460
461#ifdef CONFIG_BLK_DEV_ZONED
462static int flakey_report_zones(struct dm_target *ti,
463 struct dm_report_zones_args *args, unsigned int nr_zones)
464{
465 struct flakey_c *fc = ti->private;
466 sector_t sector = flakey_map_sector(ti, args->next_sector);
467
468 args->start = fc->start;
469 return blkdev_report_zones(fc->dev->bdev, sector, nr_zones,
470 dm_report_zones_cb, args);
471}
472#endif
473
474static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
475{
476 struct flakey_c *fc = ti->private;
477
478 return fn(ti, fc->dev, fc->start, ti->len, data);
479}
480
481static struct target_type flakey_target = {
482 .name = "flakey",
483 .version = {1, 5, 0},
484#ifdef CONFIG_BLK_DEV_ZONED
485 .features = DM_TARGET_ZONED_HM,
486 .report_zones = flakey_report_zones,
487#endif
488 .module = THIS_MODULE,
489 .ctr = flakey_ctr,
490 .dtr = flakey_dtr,
491 .map = flakey_map,
492 .end_io = flakey_end_io,
493 .status = flakey_status,
494 .prepare_ioctl = flakey_prepare_ioctl,
495 .iterate_devices = flakey_iterate_devices,
496};
497
498static int __init dm_flakey_init(void)
499{
500 int r = dm_register_target(&flakey_target);
501
502 if (r < 0)
503 DMERR("register failed %d", r);
504
505 return r;
506}
507
508static void __exit dm_flakey_exit(void)
509{
510 dm_unregister_target(&flakey_target);
511}
512
513/* Module hooks */
514module_init(dm_flakey_init);
515module_exit(dm_flakey_exit);
516
517MODULE_DESCRIPTION(DM_NAME " flakey target");
518MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
519MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2003 Sistina Software (UK) Limited.
3 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include <linux/device-mapper.h>
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/blkdev.h>
13#include <linux/bio.h>
14#include <linux/slab.h>
15
16#define DM_MSG_PREFIX "flakey"
17
18#define all_corrupt_bio_flags_match(bio, fc) \
19 (((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
20
21/*
22 * Flakey: Used for testing only, simulates intermittent,
23 * catastrophic device failure.
24 */
25struct flakey_c {
26 struct dm_dev *dev;
27 unsigned long start_time;
28 sector_t start;
29 unsigned up_interval;
30 unsigned down_interval;
31 unsigned long flags;
32 unsigned corrupt_bio_byte;
33 unsigned corrupt_bio_rw;
34 unsigned corrupt_bio_value;
35 unsigned corrupt_bio_flags;
36};
37
38enum feature_flag_bits {
39 DROP_WRITES
40};
41
42struct per_bio_data {
43 bool bio_submitted;
44};
45
46static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
47 struct dm_target *ti)
48{
49 int r;
50 unsigned argc;
51 const char *arg_name;
52
53 static struct dm_arg _args[] = {
54 {0, 6, "Invalid number of feature args"},
55 {1, UINT_MAX, "Invalid corrupt bio byte"},
56 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
57 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
58 };
59
60 /* No feature arguments supplied. */
61 if (!as->argc)
62 return 0;
63
64 r = dm_read_arg_group(_args, as, &argc, &ti->error);
65 if (r)
66 return r;
67
68 while (argc) {
69 arg_name = dm_shift_arg(as);
70 argc--;
71
72 /*
73 * drop_writes
74 */
75 if (!strcasecmp(arg_name, "drop_writes")) {
76 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
77 ti->error = "Feature drop_writes duplicated";
78 return -EINVAL;
79 }
80
81 continue;
82 }
83
84 /*
85 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
86 */
87 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
88 if (!argc) {
89 ti->error = "Feature corrupt_bio_byte requires parameters";
90 return -EINVAL;
91 }
92
93 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
94 if (r)
95 return r;
96 argc--;
97
98 /*
99 * Direction r or w?
100 */
101 arg_name = dm_shift_arg(as);
102 if (!strcasecmp(arg_name, "w"))
103 fc->corrupt_bio_rw = WRITE;
104 else if (!strcasecmp(arg_name, "r"))
105 fc->corrupt_bio_rw = READ;
106 else {
107 ti->error = "Invalid corrupt bio direction (r or w)";
108 return -EINVAL;
109 }
110 argc--;
111
112 /*
113 * Value of byte (0-255) to write in place of correct one.
114 */
115 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
116 if (r)
117 return r;
118 argc--;
119
120 /*
121 * Only corrupt bios with these flags set.
122 */
123 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
124 if (r)
125 return r;
126 argc--;
127
128 continue;
129 }
130
131 ti->error = "Unrecognised flakey feature requested";
132 return -EINVAL;
133 }
134
135 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
136 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
137 return -EINVAL;
138 }
139
140 return 0;
141}
142
143/*
144 * Construct a flakey mapping:
145 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
146 *
147 * Feature args:
148 * [drop_writes]
149 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
150 *
151 * Nth_byte starts from 1 for the first byte.
152 * Direction is r for READ or w for WRITE.
153 * bio_flags is ignored if 0.
154 */
155static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
156{
157 static struct dm_arg _args[] = {
158 {0, UINT_MAX, "Invalid up interval"},
159 {0, UINT_MAX, "Invalid down interval"},
160 };
161
162 int r;
163 struct flakey_c *fc;
164 unsigned long long tmpll;
165 struct dm_arg_set as;
166 const char *devname;
167 char dummy;
168
169 as.argc = argc;
170 as.argv = argv;
171
172 if (argc < 4) {
173 ti->error = "Invalid argument count";
174 return -EINVAL;
175 }
176
177 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
178 if (!fc) {
179 ti->error = "Cannot allocate context";
180 return -ENOMEM;
181 }
182 fc->start_time = jiffies;
183
184 devname = dm_shift_arg(&as);
185
186 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
187 ti->error = "Invalid device sector";
188 goto bad;
189 }
190 fc->start = tmpll;
191
192 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
193 if (r)
194 goto bad;
195
196 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
197 if (r)
198 goto bad;
199
200 if (!(fc->up_interval + fc->down_interval)) {
201 ti->error = "Total (up + down) interval is zero";
202 goto bad;
203 }
204
205 if (fc->up_interval + fc->down_interval < fc->up_interval) {
206 ti->error = "Interval overflow";
207 goto bad;
208 }
209
210 r = parse_features(&as, fc, ti);
211 if (r)
212 goto bad;
213
214 if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
215 ti->error = "Device lookup failed";
216 goto bad;
217 }
218
219 ti->num_flush_bios = 1;
220 ti->num_discard_bios = 1;
221 ti->per_bio_data_size = sizeof(struct per_bio_data);
222 ti->private = fc;
223 return 0;
224
225bad:
226 kfree(fc);
227 return -EINVAL;
228}
229
230static void flakey_dtr(struct dm_target *ti)
231{
232 struct flakey_c *fc = ti->private;
233
234 dm_put_device(ti, fc->dev);
235 kfree(fc);
236}
237
238static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
239{
240 struct flakey_c *fc = ti->private;
241
242 return fc->start + dm_target_offset(ti, bi_sector);
243}
244
245static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
246{
247 struct flakey_c *fc = ti->private;
248
249 bio->bi_bdev = fc->dev->bdev;
250 if (bio_sectors(bio))
251 bio->bi_iter.bi_sector =
252 flakey_map_sector(ti, bio->bi_iter.bi_sector);
253}
254
255static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
256{
257 unsigned bio_bytes = bio_cur_bytes(bio);
258 char *data = bio_data(bio);
259
260 /*
261 * Overwrite the Nth byte of the data returned.
262 */
263 if (data && bio_bytes >= fc->corrupt_bio_byte) {
264 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
265
266 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
267 "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
268 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
269 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw,
270 (unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
271 }
272}
273
274static int flakey_map(struct dm_target *ti, struct bio *bio)
275{
276 struct flakey_c *fc = ti->private;
277 unsigned elapsed;
278 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
279 pb->bio_submitted = false;
280
281 /* Are we alive ? */
282 elapsed = (jiffies - fc->start_time) / HZ;
283 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
284 /*
285 * Flag this bio as submitted while down.
286 */
287 pb->bio_submitted = true;
288
289 /*
290 * Map reads as normal.
291 */
292 if (bio_data_dir(bio) == READ)
293 goto map_bio;
294
295 /*
296 * Drop writes?
297 */
298 if (test_bit(DROP_WRITES, &fc->flags)) {
299 bio_endio(bio, 0);
300 return DM_MAPIO_SUBMITTED;
301 }
302
303 /*
304 * Corrupt matching writes.
305 */
306 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
307 if (all_corrupt_bio_flags_match(bio, fc))
308 corrupt_bio_data(bio, fc);
309 goto map_bio;
310 }
311
312 /*
313 * By default, error all I/O.
314 */
315 return -EIO;
316 }
317
318map_bio:
319 flakey_map_bio(ti, bio);
320
321 return DM_MAPIO_REMAPPED;
322}
323
324static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
325{
326 struct flakey_c *fc = ti->private;
327 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
328
329 /*
330 * Corrupt successful READs while in down state.
331 * If flags were specified, only corrupt those that match.
332 */
333 if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
334 (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
335 all_corrupt_bio_flags_match(bio, fc))
336 corrupt_bio_data(bio, fc);
337
338 return error;
339}
340
341static void flakey_status(struct dm_target *ti, status_type_t type,
342 unsigned status_flags, char *result, unsigned maxlen)
343{
344 unsigned sz = 0;
345 struct flakey_c *fc = ti->private;
346 unsigned drop_writes;
347
348 switch (type) {
349 case STATUSTYPE_INFO:
350 result[0] = '\0';
351 break;
352
353 case STATUSTYPE_TABLE:
354 DMEMIT("%s %llu %u %u ", fc->dev->name,
355 (unsigned long long)fc->start, fc->up_interval,
356 fc->down_interval);
357
358 drop_writes = test_bit(DROP_WRITES, &fc->flags);
359 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
360
361 if (drop_writes)
362 DMEMIT("drop_writes ");
363
364 if (fc->corrupt_bio_byte)
365 DMEMIT("corrupt_bio_byte %u %c %u %u ",
366 fc->corrupt_bio_byte,
367 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
368 fc->corrupt_bio_value, fc->corrupt_bio_flags);
369
370 break;
371 }
372}
373
374static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
375{
376 struct flakey_c *fc = ti->private;
377 struct dm_dev *dev = fc->dev;
378 int r = 0;
379
380 /*
381 * Only pass ioctls through if the device sizes match exactly.
382 */
383 if (fc->start ||
384 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
385 r = scsi_verify_blk_ioctl(NULL, cmd);
386
387 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
388}
389
390static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
391 struct bio_vec *biovec, int max_size)
392{
393 struct flakey_c *fc = ti->private;
394 struct request_queue *q = bdev_get_queue(fc->dev->bdev);
395
396 if (!q->merge_bvec_fn)
397 return max_size;
398
399 bvm->bi_bdev = fc->dev->bdev;
400 bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
401
402 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
403}
404
405static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
406{
407 struct flakey_c *fc = ti->private;
408
409 return fn(ti, fc->dev, fc->start, ti->len, data);
410}
411
412static struct target_type flakey_target = {
413 .name = "flakey",
414 .version = {1, 3, 1},
415 .module = THIS_MODULE,
416 .ctr = flakey_ctr,
417 .dtr = flakey_dtr,
418 .map = flakey_map,
419 .end_io = flakey_end_io,
420 .status = flakey_status,
421 .ioctl = flakey_ioctl,
422 .merge = flakey_merge,
423 .iterate_devices = flakey_iterate_devices,
424};
425
426static int __init dm_flakey_init(void)
427{
428 int r = dm_register_target(&flakey_target);
429
430 if (r < 0)
431 DMERR("register failed %d", r);
432
433 return r;
434}
435
436static void __exit dm_flakey_exit(void)
437{
438 dm_unregister_target(&flakey_target);
439}
440
441/* Module hooks */
442module_init(dm_flakey_init);
443module_exit(dm_flakey_exit);
444
445MODULE_DESCRIPTION(DM_NAME " flakey target");
446MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
447MODULE_LICENSE("GPL");