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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
23
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
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
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
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
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
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
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
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
174
175
176
177
178
179
180
181
182
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
300
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
329 elapsed = (jiffies - fc->start_time) / HZ;
330 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
331
332
333
334 pb->bio_submitted = true;
335
336
337
338
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
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
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
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
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
401
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
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
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");
520
