1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2003 Sistina Software (UK) Limited.
4 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
5 *
6 * This file is released under the GPL.
7 */
8
9 #include <linux/device-mapper.h>
10
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/blkdev.h>
14 #include <linux/bio.h>
15 #include <linux/slab.h>
16
17 #define DM_MSG_PREFIX "flakey"
18
19 #define all_corrupt_bio_flags_match(bio, fc) \
20 (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
21
22 /*
23 * Flakey: Used for testing only, simulates intermittent,
24 * catastrophic device failure.
25 */
26 struct flakey_c {
27 struct dm_dev *dev;
28 unsigned long start_time;
29 sector_t start;
30 unsigned int up_interval;
31 unsigned int down_interval;
32 unsigned long flags;
33 unsigned int corrupt_bio_byte;
34 unsigned int corrupt_bio_rw;
35 unsigned int corrupt_bio_value;
36 blk_opf_t corrupt_bio_flags;
37 };
38
39 enum feature_flag_bits {
40 DROP_WRITES,
41 ERROR_WRITES
42 };
43
44 struct per_bio_data {
45 bool bio_submitted;
46 };
47
parse_features(struct dm_arg_set * as,struct flakey_c * fc,struct dm_target * ti)48 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
49 struct dm_target *ti)
50 {
51 int r;
52 unsigned int argc;
53 const char *arg_name;
54
55 static const struct dm_arg _args[] = {
56 {0, 6, "Invalid number of feature args"},
57 {1, UINT_MAX, "Invalid corrupt bio byte"},
58 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
59 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
60 };
61
62 /* No feature arguments supplied. */
63 if (!as->argc)
64 return 0;
65
66 r = dm_read_arg_group(_args, as, &argc, &ti->error);
67 if (r)
68 return r;
69
70 while (argc) {
71 arg_name = dm_shift_arg(as);
72 argc--;
73
74 if (!arg_name) {
75 ti->error = "Insufficient feature arguments";
76 return -EINVAL;
77 }
78
79 /*
80 * drop_writes
81 */
82 if (!strcasecmp(arg_name, "drop_writes")) {
83 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
84 ti->error = "Feature drop_writes duplicated";
85 return -EINVAL;
86 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
87 ti->error = "Feature drop_writes conflicts with feature error_writes";
88 return -EINVAL;
89 }
90
91 continue;
92 }
93
94 /*
95 * error_writes
96 */
97 if (!strcasecmp(arg_name, "error_writes")) {
98 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
99 ti->error = "Feature error_writes duplicated";
100 return -EINVAL;
101
102 } else if (test_bit(DROP_WRITES, &fc->flags)) {
103 ti->error = "Feature error_writes conflicts with feature drop_writes";
104 return -EINVAL;
105 }
106
107 continue;
108 }
109
110 /*
111 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
112 */
113 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
114 if (!argc) {
115 ti->error = "Feature corrupt_bio_byte requires parameters";
116 return -EINVAL;
117 }
118
119 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
120 if (r)
121 return r;
122 argc--;
123
124 /*
125 * Direction r or w?
126 */
127 arg_name = dm_shift_arg(as);
128 if (!strcasecmp(arg_name, "w"))
129 fc->corrupt_bio_rw = WRITE;
130 else if (!strcasecmp(arg_name, "r"))
131 fc->corrupt_bio_rw = READ;
132 else {
133 ti->error = "Invalid corrupt bio direction (r or w)";
134 return -EINVAL;
135 }
136 argc--;
137
138 /*
139 * Value of byte (0-255) to write in place of correct one.
140 */
141 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
142 if (r)
143 return r;
144 argc--;
145
146 /*
147 * Only corrupt bios with these flags set.
148 */
149 BUILD_BUG_ON(sizeof(fc->corrupt_bio_flags) !=
150 sizeof(unsigned int));
151 r = dm_read_arg(_args + 3, as,
152 (__force unsigned int *)&fc->corrupt_bio_flags,
153 &ti->error);
154 if (r)
155 return r;
156 argc--;
157
158 continue;
159 }
160
161 ti->error = "Unrecognised flakey feature requested";
162 return -EINVAL;
163 }
164
165 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
166 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
167 return -EINVAL;
168
169 } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
170 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
171 return -EINVAL;
172 }
173
174 return 0;
175 }
176
177 /*
178 * Construct a flakey mapping:
179 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
180 *
181 * Feature args:
182 * [drop_writes]
183 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
184 *
185 * Nth_byte starts from 1 for the first byte.
186 * Direction is r for READ or w for WRITE.
187 * bio_flags is ignored if 0.
188 */
flakey_ctr(struct dm_target * ti,unsigned int argc,char ** argv)189 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
190 {
191 static const struct dm_arg _args[] = {
192 {0, UINT_MAX, "Invalid up interval"},
193 {0, UINT_MAX, "Invalid down interval"},
194 };
195
196 int r;
197 struct flakey_c *fc;
198 unsigned long long tmpll;
199 struct dm_arg_set as;
200 const char *devname;
201 char dummy;
202
203 as.argc = argc;
204 as.argv = argv;
205
206 if (argc < 4) {
207 ti->error = "Invalid argument count";
208 return -EINVAL;
209 }
210
211 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
212 if (!fc) {
213 ti->error = "Cannot allocate context";
214 return -ENOMEM;
215 }
216 fc->start_time = jiffies;
217
218 devname = dm_shift_arg(&as);
219
220 r = -EINVAL;
221 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
222 ti->error = "Invalid device sector";
223 goto bad;
224 }
225 fc->start = tmpll;
226
227 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
228 if (r)
229 goto bad;
230
231 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
232 if (r)
233 goto bad;
234
235 if (!(fc->up_interval + fc->down_interval)) {
236 ti->error = "Total (up + down) interval is zero";
237 r = -EINVAL;
238 goto bad;
239 }
240
241 if (fc->up_interval + fc->down_interval < fc->up_interval) {
242 ti->error = "Interval overflow";
243 r = -EINVAL;
244 goto bad;
245 }
246
247 r = parse_features(&as, fc, ti);
248 if (r)
249 goto bad;
250
251 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
252 if (r) {
253 ti->error = "Device lookup failed";
254 goto bad;
255 }
256
257 ti->num_flush_bios = 1;
258 ti->num_discard_bios = 1;
259 ti->per_io_data_size = sizeof(struct per_bio_data);
260 ti->private = fc;
261 return 0;
262
263 bad:
264 kfree(fc);
265 return r;
266 }
267
flakey_dtr(struct dm_target * ti)268 static void flakey_dtr(struct dm_target *ti)
269 {
270 struct flakey_c *fc = ti->private;
271
272 dm_put_device(ti, fc->dev);
273 kfree(fc);
274 }
275
flakey_map_sector(struct dm_target * ti,sector_t bi_sector)276 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
277 {
278 struct flakey_c *fc = ti->private;
279
280 return fc->start + dm_target_offset(ti, bi_sector);
281 }
282
flakey_map_bio(struct dm_target * ti,struct bio * bio)283 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
284 {
285 struct flakey_c *fc = ti->private;
286
287 bio_set_dev(bio, fc->dev->bdev);
288 bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
289 }
290
corrupt_bio_data(struct bio * bio,struct flakey_c * fc)291 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
292 {
293 unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
294
295 struct bvec_iter iter;
296 struct bio_vec bvec;
297
298 if (!bio_has_data(bio))
299 return;
300
301 /*
302 * Overwrite the Nth byte of the bio's data, on whichever page
303 * it falls.
304 */
305 bio_for_each_segment(bvec, bio, iter) {
306 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
307 char *segment;
308 struct page *page = bio_iter_page(bio, iter);
309 if (unlikely(page == ZERO_PAGE(0)))
310 break;
311 segment = bvec_kmap_local(&bvec);
312 segment[corrupt_bio_byte] = fc->corrupt_bio_value;
313 kunmap_local(segment);
314 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
315 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
316 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
317 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
318 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
319 break;
320 }
321 corrupt_bio_byte -= bio_iter_len(bio, iter);
322 }
323 }
324
flakey_map(struct dm_target * ti,struct bio * bio)325 static int flakey_map(struct dm_target *ti, struct bio *bio)
326 {
327 struct flakey_c *fc = ti->private;
328 unsigned int elapsed;
329 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
330
331 pb->bio_submitted = false;
332
333 if (op_is_zone_mgmt(bio_op(bio)))
334 goto map_bio;
335
336 /* Are we alive ? */
337 elapsed = (jiffies - fc->start_time) / HZ;
338 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
339 /*
340 * Flag this bio as submitted while down.
341 */
342 pb->bio_submitted = true;
343
344 /*
345 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
346 * Otherwise, flakey_end_io() will decide if the reads should be modified.
347 */
348 if (bio_data_dir(bio) == READ) {
349 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
350 !test_bit(ERROR_WRITES, &fc->flags))
351 return DM_MAPIO_KILL;
352 goto map_bio;
353 }
354
355 /*
356 * Drop or error writes?
357 */
358 if (test_bit(DROP_WRITES, &fc->flags)) {
359 bio_endio(bio);
360 return DM_MAPIO_SUBMITTED;
361 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
362 bio_io_error(bio);
363 return DM_MAPIO_SUBMITTED;
364 }
365
366 /*
367 * Corrupt matching writes.
368 */
369 if (fc->corrupt_bio_byte) {
370 if (fc->corrupt_bio_rw == WRITE) {
371 if (all_corrupt_bio_flags_match(bio, fc))
372 corrupt_bio_data(bio, fc);
373 }
374 goto map_bio;
375 }
376
377 /*
378 * By default, error all I/O.
379 */
380 return DM_MAPIO_KILL;
381 }
382
383 map_bio:
384 flakey_map_bio(ti, bio);
385
386 return DM_MAPIO_REMAPPED;
387 }
388
flakey_end_io(struct dm_target * ti,struct bio * bio,blk_status_t * error)389 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
390 blk_status_t *error)
391 {
392 struct flakey_c *fc = ti->private;
393 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
394
395 if (op_is_zone_mgmt(bio_op(bio)))
396 return DM_ENDIO_DONE;
397
398 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
399 if (fc->corrupt_bio_byte) {
400 if ((fc->corrupt_bio_rw == READ) &&
401 all_corrupt_bio_flags_match(bio, fc)) {
402 /*
403 * Corrupt successful matching READs while in down state.
404 */
405 corrupt_bio_data(bio, fc);
406 }
407 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
408 !test_bit(ERROR_WRITES, &fc->flags)) {
409 /*
410 * Error read during the down_interval if drop_writes
411 * and error_writes were not configured.
412 */
413 *error = BLK_STS_IOERR;
414 }
415 }
416
417 return DM_ENDIO_DONE;
418 }
419
flakey_status(struct dm_target * ti,status_type_t type,unsigned int status_flags,char * result,unsigned int maxlen)420 static void flakey_status(struct dm_target *ti, status_type_t type,
421 unsigned int status_flags, char *result, unsigned int maxlen)
422 {
423 unsigned int sz = 0;
424 struct flakey_c *fc = ti->private;
425 unsigned int drop_writes, error_writes;
426
427 switch (type) {
428 case STATUSTYPE_INFO:
429 result[0] = '\0';
430 break;
431
432 case STATUSTYPE_TABLE:
433 DMEMIT("%s %llu %u %u ", fc->dev->name,
434 (unsigned long long)fc->start, fc->up_interval,
435 fc->down_interval);
436
437 drop_writes = test_bit(DROP_WRITES, &fc->flags);
438 error_writes = test_bit(ERROR_WRITES, &fc->flags);
439 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
440
441 if (drop_writes)
442 DMEMIT("drop_writes ");
443 else if (error_writes)
444 DMEMIT("error_writes ");
445
446 if (fc->corrupt_bio_byte)
447 DMEMIT("corrupt_bio_byte %u %c %u %u ",
448 fc->corrupt_bio_byte,
449 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
450 fc->corrupt_bio_value, fc->corrupt_bio_flags);
451
452 break;
453
454 case STATUSTYPE_IMA:
455 result[0] = '\0';
456 break;
457 }
458 }
459
flakey_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev)460 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
461 {
462 struct flakey_c *fc = ti->private;
463
464 *bdev = fc->dev->bdev;
465
466 /*
467 * Only pass ioctls through if the device sizes match exactly.
468 */
469 if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
470 return 1;
471 return 0;
472 }
473
474 #ifdef CONFIG_BLK_DEV_ZONED
flakey_report_zones(struct dm_target * ti,struct dm_report_zones_args * args,unsigned int nr_zones)475 static int flakey_report_zones(struct dm_target *ti,
476 struct dm_report_zones_args *args, unsigned int nr_zones)
477 {
478 struct flakey_c *fc = ti->private;
479
480 return dm_report_zones(fc->dev->bdev, fc->start,
481 flakey_map_sector(ti, args->next_sector),
482 args, nr_zones);
483 }
484 #else
485 #define flakey_report_zones NULL
486 #endif
487
flakey_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)488 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
489 {
490 struct flakey_c *fc = ti->private;
491
492 return fn(ti, fc->dev, fc->start, ti->len, data);
493 }
494
495 static struct target_type flakey_target = {
496 .name = "flakey",
497 .version = {1, 5, 0},
498 .features = DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
499 .report_zones = flakey_report_zones,
500 .module = THIS_MODULE,
501 .ctr = flakey_ctr,
502 .dtr = flakey_dtr,
503 .map = flakey_map,
504 .end_io = flakey_end_io,
505 .status = flakey_status,
506 .prepare_ioctl = flakey_prepare_ioctl,
507 .iterate_devices = flakey_iterate_devices,
508 };
509
dm_flakey_init(void)510 static int __init dm_flakey_init(void)
511 {
512 int r = dm_register_target(&flakey_target);
513
514 if (r < 0)
515 DMERR("register failed %d", r);
516
517 return r;
518 }
519
dm_flakey_exit(void)520 static void __exit dm_flakey_exit(void)
521 {
522 dm_unregister_target(&flakey_target);
523 }
524
525 /* Module hooks */
526 module_init(dm_flakey_init);
527 module_exit(dm_flakey_exit);
528
529 MODULE_DESCRIPTION(DM_NAME " flakey target");
530 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
531 MODULE_LICENSE("GPL");
532