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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 PROBABILITY_BASE 1000000000
20
21#define all_corrupt_bio_flags_match(bio, fc) \
22 (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
23
24/*
25 * Flakey: Used for testing only, simulates intermittent,
26 * catastrophic device failure.
27 */
28struct flakey_c {
29 struct dm_dev *dev;
30 unsigned long start_time;
31 sector_t start;
32 unsigned int up_interval;
33 unsigned int down_interval;
34 unsigned long flags;
35 unsigned int corrupt_bio_byte;
36 unsigned int corrupt_bio_rw;
37 unsigned int corrupt_bio_value;
38 blk_opf_t corrupt_bio_flags;
39 unsigned int random_read_corrupt;
40 unsigned int random_write_corrupt;
41};
42
43enum feature_flag_bits {
44 ERROR_READS,
45 DROP_WRITES,
46 ERROR_WRITES
47};
48
49struct per_bio_data {
50 bool bio_submitted;
51};
52
53static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
54 struct dm_target *ti)
55{
56 int r;
57 unsigned int argc;
58 const char *arg_name;
59
60 static const struct dm_arg _args[] = {
61 {0, 11, "Invalid number of feature args"},
62 {1, UINT_MAX, "Invalid corrupt bio byte"},
63 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
64 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
65 {0, PROBABILITY_BASE, "Invalid random corrupt argument"},
66 };
67
68 /* No feature arguments supplied. */
69 if (!as->argc)
70 return 0;
71
72 r = dm_read_arg_group(_args, as, &argc, &ti->error);
73 if (r)
74 return r;
75
76 while (argc) {
77 arg_name = dm_shift_arg(as);
78 argc--;
79
80 if (!arg_name) {
81 ti->error = "Insufficient feature arguments";
82 return -EINVAL;
83 }
84
85 /*
86 * error_reads
87 */
88 if (!strcasecmp(arg_name, "error_reads")) {
89 if (test_and_set_bit(ERROR_READS, &fc->flags)) {
90 ti->error = "Feature error_reads duplicated";
91 return -EINVAL;
92 }
93 continue;
94 }
95
96 /*
97 * drop_writes
98 */
99 if (!strcasecmp(arg_name, "drop_writes")) {
100 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
101 ti->error = "Feature drop_writes duplicated";
102 return -EINVAL;
103 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
104 ti->error = "Feature drop_writes conflicts with feature error_writes";
105 return -EINVAL;
106 }
107
108 continue;
109 }
110
111 /*
112 * error_writes
113 */
114 if (!strcasecmp(arg_name, "error_writes")) {
115 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
116 ti->error = "Feature error_writes duplicated";
117 return -EINVAL;
118
119 } else if (test_bit(DROP_WRITES, &fc->flags)) {
120 ti->error = "Feature error_writes conflicts with feature drop_writes";
121 return -EINVAL;
122 }
123
124 continue;
125 }
126
127 /*
128 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
129 */
130 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
131 if (!argc) {
132 ti->error = "Feature corrupt_bio_byte requires parameters";
133 return -EINVAL;
134 }
135
136 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
137 if (r)
138 return r;
139 argc--;
140
141 /*
142 * Direction r or w?
143 */
144 arg_name = dm_shift_arg(as);
145 if (arg_name && !strcasecmp(arg_name, "w"))
146 fc->corrupt_bio_rw = WRITE;
147 else if (arg_name && !strcasecmp(arg_name, "r"))
148 fc->corrupt_bio_rw = READ;
149 else {
150 ti->error = "Invalid corrupt bio direction (r or w)";
151 return -EINVAL;
152 }
153 argc--;
154
155 /*
156 * Value of byte (0-255) to write in place of correct one.
157 */
158 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
159 if (r)
160 return r;
161 argc--;
162
163 /*
164 * Only corrupt bios with these flags set.
165 */
166 BUILD_BUG_ON(sizeof(fc->corrupt_bio_flags) !=
167 sizeof(unsigned int));
168 r = dm_read_arg(_args + 3, as,
169 (__force unsigned int *)&fc->corrupt_bio_flags,
170 &ti->error);
171 if (r)
172 return r;
173 argc--;
174
175 continue;
176 }
177
178 if (!strcasecmp(arg_name, "random_read_corrupt")) {
179 if (!argc) {
180 ti->error = "Feature random_read_corrupt requires a parameter";
181 return -EINVAL;
182 }
183 r = dm_read_arg(_args + 4, as, &fc->random_read_corrupt, &ti->error);
184 if (r)
185 return r;
186 argc--;
187
188 continue;
189 }
190
191 if (!strcasecmp(arg_name, "random_write_corrupt")) {
192 if (!argc) {
193 ti->error = "Feature random_write_corrupt requires a parameter";
194 return -EINVAL;
195 }
196 r = dm_read_arg(_args + 4, as, &fc->random_write_corrupt, &ti->error);
197 if (r)
198 return r;
199 argc--;
200
201 continue;
202 }
203
204 ti->error = "Unrecognised flakey feature requested";
205 return -EINVAL;
206 }
207
208 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
209 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
210 return -EINVAL;
211
212 } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
213 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
214 return -EINVAL;
215 }
216
217 if (!fc->corrupt_bio_byte && !test_bit(ERROR_READS, &fc->flags) &&
218 !test_bit(DROP_WRITES, &fc->flags) && !test_bit(ERROR_WRITES, &fc->flags) &&
219 !fc->random_read_corrupt && !fc->random_write_corrupt) {
220 set_bit(ERROR_WRITES, &fc->flags);
221 set_bit(ERROR_READS, &fc->flags);
222 }
223
224 return 0;
225}
226
227/*
228 * Construct a flakey mapping:
229 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
230 *
231 * Feature args:
232 * [drop_writes]
233 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
234 *
235 * Nth_byte starts from 1 for the first byte.
236 * Direction is r for READ or w for WRITE.
237 * bio_flags is ignored if 0.
238 */
239static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
240{
241 static const struct dm_arg _args[] = {
242 {0, UINT_MAX, "Invalid up interval"},
243 {0, UINT_MAX, "Invalid down interval"},
244 };
245
246 int r;
247 struct flakey_c *fc;
248 unsigned long long tmpll;
249 struct dm_arg_set as;
250 const char *devname;
251 char dummy;
252
253 as.argc = argc;
254 as.argv = argv;
255
256 if (argc < 4) {
257 ti->error = "Invalid argument count";
258 return -EINVAL;
259 }
260
261 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
262 if (!fc) {
263 ti->error = "Cannot allocate context";
264 return -ENOMEM;
265 }
266 fc->start_time = jiffies;
267
268 devname = dm_shift_arg(&as);
269
270 r = -EINVAL;
271 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
272 ti->error = "Invalid device sector";
273 goto bad;
274 }
275 fc->start = tmpll;
276
277 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
278 if (r)
279 goto bad;
280
281 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
282 if (r)
283 goto bad;
284
285 if (!(fc->up_interval + fc->down_interval)) {
286 ti->error = "Total (up + down) interval is zero";
287 r = -EINVAL;
288 goto bad;
289 }
290
291 if (fc->up_interval + fc->down_interval < fc->up_interval) {
292 ti->error = "Interval overflow";
293 r = -EINVAL;
294 goto bad;
295 }
296
297 r = parse_features(&as, fc, ti);
298 if (r)
299 goto bad;
300
301 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
302 if (r) {
303 ti->error = "Device lookup failed";
304 goto bad;
305 }
306
307 ti->num_flush_bios = 1;
308 ti->num_discard_bios = 1;
309 ti->per_io_data_size = sizeof(struct per_bio_data);
310 ti->private = fc;
311 return 0;
312
313bad:
314 kfree(fc);
315 return r;
316}
317
318static void flakey_dtr(struct dm_target *ti)
319{
320 struct flakey_c *fc = ti->private;
321
322 dm_put_device(ti, fc->dev);
323 kfree(fc);
324}
325
326static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
327{
328 struct flakey_c *fc = ti->private;
329
330 return fc->start + dm_target_offset(ti, bi_sector);
331}
332
333static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
334{
335 struct flakey_c *fc = ti->private;
336
337 bio_set_dev(bio, fc->dev->bdev);
338 bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
339}
340
341static void corrupt_bio_common(struct bio *bio, unsigned int corrupt_bio_byte,
342 unsigned char corrupt_bio_value)
343{
344 struct bvec_iter iter;
345 struct bio_vec bvec;
346
347 /*
348 * Overwrite the Nth byte of the bio's data, on whichever page
349 * it falls.
350 */
351 bio_for_each_segment(bvec, bio, iter) {
352 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
353 unsigned char *segment = bvec_kmap_local(&bvec);
354 segment[corrupt_bio_byte] = corrupt_bio_value;
355 kunmap_local(segment);
356 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
357 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
358 bio, corrupt_bio_value, corrupt_bio_byte,
359 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
360 (unsigned long long)bio->bi_iter.bi_sector,
361 bio->bi_iter.bi_size);
362 break;
363 }
364 corrupt_bio_byte -= bio_iter_len(bio, iter);
365 }
366}
367
368static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
369{
370 unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
371
372 if (!bio_has_data(bio))
373 return;
374
375 corrupt_bio_common(bio, corrupt_bio_byte, fc->corrupt_bio_value);
376}
377
378static void corrupt_bio_random(struct bio *bio)
379{
380 unsigned int corrupt_byte;
381 unsigned char corrupt_value;
382
383 if (!bio_has_data(bio))
384 return;
385
386 corrupt_byte = get_random_u32() % bio->bi_iter.bi_size;
387 corrupt_value = get_random_u8();
388
389 corrupt_bio_common(bio, corrupt_byte, corrupt_value);
390}
391
392static void clone_free(struct bio *clone)
393{
394 struct folio_iter fi;
395
396 if (clone->bi_vcnt > 0) { /* bio_for_each_folio_all crashes with an empty bio */
397 bio_for_each_folio_all(fi, clone)
398 folio_put(fi.folio);
399 }
400
401 bio_uninit(clone);
402 kfree(clone);
403}
404
405static void clone_endio(struct bio *clone)
406{
407 struct bio *bio = clone->bi_private;
408 bio->bi_status = clone->bi_status;
409 clone_free(clone);
410 bio_endio(bio);
411}
412
413static struct bio *clone_bio(struct dm_target *ti, struct flakey_c *fc, struct bio *bio)
414{
415 struct bio *clone;
416 unsigned size, remaining_size, nr_iovecs, order;
417 struct bvec_iter iter = bio->bi_iter;
418
419 if (unlikely(bio->bi_iter.bi_size > UIO_MAXIOV << PAGE_SHIFT))
420 dm_accept_partial_bio(bio, UIO_MAXIOV << PAGE_SHIFT >> SECTOR_SHIFT);
421
422 size = bio->bi_iter.bi_size;
423 nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
424
425 clone = bio_kmalloc(nr_iovecs, GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
426 if (!clone)
427 return NULL;
428
429 bio_init(clone, fc->dev->bdev, bio->bi_inline_vecs, nr_iovecs, bio->bi_opf);
430
431 clone->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
432 clone->bi_private = bio;
433 clone->bi_end_io = clone_endio;
434
435 remaining_size = size;
436
437 order = MAX_PAGE_ORDER;
438 while (remaining_size) {
439 struct page *pages;
440 unsigned size_to_add, to_copy;
441 unsigned char *virt;
442 unsigned remaining_order = __fls((remaining_size + PAGE_SIZE - 1) >> PAGE_SHIFT);
443 order = min(order, remaining_order);
444
445retry_alloc_pages:
446 pages = alloc_pages(GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN | __GFP_COMP, order);
447 if (unlikely(!pages)) {
448 if (order) {
449 order--;
450 goto retry_alloc_pages;
451 }
452 clone_free(clone);
453 return NULL;
454 }
455 size_to_add = min((unsigned)PAGE_SIZE << order, remaining_size);
456
457 virt = page_to_virt(pages);
458 to_copy = size_to_add;
459 do {
460 struct bio_vec bvec = bvec_iter_bvec(bio->bi_io_vec, iter);
461 unsigned this_step = min(bvec.bv_len, to_copy);
462 void *map = bvec_kmap_local(&bvec);
463 memcpy(virt, map, this_step);
464 kunmap_local(map);
465
466 bvec_iter_advance(bio->bi_io_vec, &iter, this_step);
467 to_copy -= this_step;
468 virt += this_step;
469 } while (to_copy);
470
471 __bio_add_page(clone, pages, size_to_add, 0);
472 remaining_size -= size_to_add;
473 }
474
475 return clone;
476}
477
478static int flakey_map(struct dm_target *ti, struct bio *bio)
479{
480 struct flakey_c *fc = ti->private;
481 unsigned int elapsed;
482 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
483
484 pb->bio_submitted = false;
485
486 if (op_is_zone_mgmt(bio_op(bio)))
487 goto map_bio;
488
489 /* Are we alive ? */
490 elapsed = (jiffies - fc->start_time) / HZ;
491 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
492 bool corrupt_fixed, corrupt_random;
493 /*
494 * Flag this bio as submitted while down.
495 */
496 pb->bio_submitted = true;
497
498 /*
499 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
500 * Otherwise, flakey_end_io() will decide if the reads should be modified.
501 */
502 if (bio_data_dir(bio) == READ) {
503 if (test_bit(ERROR_READS, &fc->flags))
504 return DM_MAPIO_KILL;
505 goto map_bio;
506 }
507
508 /*
509 * Drop or error writes?
510 */
511 if (test_bit(DROP_WRITES, &fc->flags)) {
512 bio_endio(bio);
513 return DM_MAPIO_SUBMITTED;
514 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
515 bio_io_error(bio);
516 return DM_MAPIO_SUBMITTED;
517 }
518
519 /*
520 * Corrupt matching writes.
521 */
522 corrupt_fixed = false;
523 corrupt_random = false;
524 if (fc->corrupt_bio_byte && fc->corrupt_bio_rw == WRITE) {
525 if (all_corrupt_bio_flags_match(bio, fc))
526 corrupt_fixed = true;
527 }
528 if (fc->random_write_corrupt) {
529 u64 rnd = get_random_u64();
530 u32 rem = do_div(rnd, PROBABILITY_BASE);
531 if (rem < fc->random_write_corrupt)
532 corrupt_random = true;
533 }
534 if (corrupt_fixed || corrupt_random) {
535 struct bio *clone = clone_bio(ti, fc, bio);
536 if (clone) {
537 if (corrupt_fixed)
538 corrupt_bio_data(clone, fc);
539 if (corrupt_random)
540 corrupt_bio_random(clone);
541 submit_bio(clone);
542 return DM_MAPIO_SUBMITTED;
543 }
544 }
545 }
546
547map_bio:
548 flakey_map_bio(ti, bio);
549
550 return DM_MAPIO_REMAPPED;
551}
552
553static int flakey_end_io(struct dm_target *ti, struct bio *bio,
554 blk_status_t *error)
555{
556 struct flakey_c *fc = ti->private;
557 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
558
559 if (op_is_zone_mgmt(bio_op(bio)))
560 return DM_ENDIO_DONE;
561
562 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
563 if (fc->corrupt_bio_byte) {
564 if ((fc->corrupt_bio_rw == READ) &&
565 all_corrupt_bio_flags_match(bio, fc)) {
566 /*
567 * Corrupt successful matching READs while in down state.
568 */
569 corrupt_bio_data(bio, fc);
570 }
571 }
572 if (fc->random_read_corrupt) {
573 u64 rnd = get_random_u64();
574 u32 rem = do_div(rnd, PROBABILITY_BASE);
575 if (rem < fc->random_read_corrupt)
576 corrupt_bio_random(bio);
577 }
578 if (test_bit(ERROR_READS, &fc->flags)) {
579 /*
580 * Error read during the down_interval if drop_writes
581 * and error_writes were not configured.
582 */
583 *error = BLK_STS_IOERR;
584 }
585 }
586
587 return DM_ENDIO_DONE;
588}
589
590static void flakey_status(struct dm_target *ti, status_type_t type,
591 unsigned int status_flags, char *result, unsigned int maxlen)
592{
593 unsigned int sz = 0;
594 struct flakey_c *fc = ti->private;
595 unsigned int error_reads, drop_writes, error_writes;
596
597 switch (type) {
598 case STATUSTYPE_INFO:
599 result[0] = '\0';
600 break;
601
602 case STATUSTYPE_TABLE:
603 DMEMIT("%s %llu %u %u", fc->dev->name,
604 (unsigned long long)fc->start, fc->up_interval,
605 fc->down_interval);
606
607 error_reads = test_bit(ERROR_READS, &fc->flags);
608 drop_writes = test_bit(DROP_WRITES, &fc->flags);
609 error_writes = test_bit(ERROR_WRITES, &fc->flags);
610 DMEMIT(" %u", error_reads + drop_writes + error_writes +
611 (fc->corrupt_bio_byte > 0) * 5 +
612 (fc->random_read_corrupt > 0) * 2 +
613 (fc->random_write_corrupt > 0) * 2);
614
615 if (error_reads)
616 DMEMIT(" error_reads");
617 if (drop_writes)
618 DMEMIT(" drop_writes");
619 else if (error_writes)
620 DMEMIT(" error_writes");
621
622 if (fc->corrupt_bio_byte)
623 DMEMIT(" corrupt_bio_byte %u %c %u %u",
624 fc->corrupt_bio_byte,
625 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
626 fc->corrupt_bio_value, fc->corrupt_bio_flags);
627
628 if (fc->random_read_corrupt > 0)
629 DMEMIT(" random_read_corrupt %u", fc->random_read_corrupt);
630 if (fc->random_write_corrupt > 0)
631 DMEMIT(" random_write_corrupt %u", fc->random_write_corrupt);
632
633 break;
634
635 case STATUSTYPE_IMA:
636 result[0] = '\0';
637 break;
638 }
639}
640
641static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
642{
643 struct flakey_c *fc = ti->private;
644
645 *bdev = fc->dev->bdev;
646
647 /*
648 * Only pass ioctls through if the device sizes match exactly.
649 */
650 if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
651 return 1;
652 return 0;
653}
654
655#ifdef CONFIG_BLK_DEV_ZONED
656static int flakey_report_zones(struct dm_target *ti,
657 struct dm_report_zones_args *args, unsigned int nr_zones)
658{
659 struct flakey_c *fc = ti->private;
660
661 return dm_report_zones(fc->dev->bdev, fc->start,
662 flakey_map_sector(ti, args->next_sector),
663 args, nr_zones);
664}
665#else
666#define flakey_report_zones NULL
667#endif
668
669static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
670{
671 struct flakey_c *fc = ti->private;
672
673 return fn(ti, fc->dev, fc->start, ti->len, data);
674}
675
676static struct target_type flakey_target = {
677 .name = "flakey",
678 .version = {1, 5, 0},
679 .features = DM_TARGET_ZONED_HM | DM_TARGET_PASSES_CRYPTO,
680 .report_zones = flakey_report_zones,
681 .module = THIS_MODULE,
682 .ctr = flakey_ctr,
683 .dtr = flakey_dtr,
684 .map = flakey_map,
685 .end_io = flakey_end_io,
686 .status = flakey_status,
687 .prepare_ioctl = flakey_prepare_ioctl,
688 .iterate_devices = flakey_iterate_devices,
689};
690module_dm(flakey);
691
692MODULE_DESCRIPTION(DM_NAME " flakey target");
693MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
694MODULE_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 r = -EINVAL;
187 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
188 ti->error = "Invalid device sector";
189 goto bad;
190 }
191 fc->start = tmpll;
192
193 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
194 if (r)
195 goto bad;
196
197 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
198 if (r)
199 goto bad;
200
201 if (!(fc->up_interval + fc->down_interval)) {
202 ti->error = "Total (up + down) interval is zero";
203 goto bad;
204 }
205
206 if (fc->up_interval + fc->down_interval < fc->up_interval) {
207 ti->error = "Interval overflow";
208 goto bad;
209 }
210
211 r = parse_features(&as, fc, ti);
212 if (r)
213 goto bad;
214
215 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
216 if (r) {
217 ti->error = "Device lookup failed";
218 goto bad;
219 }
220
221 ti->num_flush_bios = 1;
222 ti->num_discard_bios = 1;
223 ti->per_io_data_size = sizeof(struct per_bio_data);
224 ti->private = fc;
225 return 0;
226
227bad:
228 kfree(fc);
229 return r;
230}
231
232static void flakey_dtr(struct dm_target *ti)
233{
234 struct flakey_c *fc = ti->private;
235
236 dm_put_device(ti, fc->dev);
237 kfree(fc);
238}
239
240static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
241{
242 struct flakey_c *fc = ti->private;
243
244 return fc->start + dm_target_offset(ti, bi_sector);
245}
246
247static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
248{
249 struct flakey_c *fc = ti->private;
250
251 bio->bi_bdev = fc->dev->bdev;
252 if (bio_sectors(bio))
253 bio->bi_iter.bi_sector =
254 flakey_map_sector(ti, bio->bi_iter.bi_sector);
255}
256
257static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
258{
259 unsigned bio_bytes = bio_cur_bytes(bio);
260 char *data = bio_data(bio);
261
262 /*
263 * Overwrite the Nth byte of the data returned.
264 */
265 if (data && bio_bytes >= fc->corrupt_bio_byte) {
266 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
267
268 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
269 "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
270 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
271 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw,
272 (unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
273 }
274}
275
276static int flakey_map(struct dm_target *ti, struct bio *bio)
277{
278 struct flakey_c *fc = ti->private;
279 unsigned elapsed;
280 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
281 pb->bio_submitted = false;
282
283 /* Are we alive ? */
284 elapsed = (jiffies - fc->start_time) / HZ;
285 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
286 /*
287 * Flag this bio as submitted while down.
288 */
289 pb->bio_submitted = true;
290
291 /*
292 * Map reads as normal.
293 */
294 if (bio_data_dir(bio) == READ)
295 goto map_bio;
296
297 /*
298 * Drop writes?
299 */
300 if (test_bit(DROP_WRITES, &fc->flags)) {
301 bio_endio(bio);
302 return DM_MAPIO_SUBMITTED;
303 }
304
305 /*
306 * Corrupt matching writes.
307 */
308 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
309 if (all_corrupt_bio_flags_match(bio, fc))
310 corrupt_bio_data(bio, fc);
311 goto map_bio;
312 }
313
314 /*
315 * By default, error all I/O.
316 */
317 return -EIO;
318 }
319
320map_bio:
321 flakey_map_bio(ti, bio);
322
323 return DM_MAPIO_REMAPPED;
324}
325
326static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
327{
328 struct flakey_c *fc = ti->private;
329 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
330
331 /*
332 * Corrupt successful READs while in down state.
333 * If flags were specified, only corrupt those that match.
334 */
335 if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
336 (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
337 all_corrupt_bio_flags_match(bio, fc))
338 corrupt_bio_data(bio, fc);
339
340 return error;
341}
342
343static void flakey_status(struct dm_target *ti, status_type_t type,
344 unsigned status_flags, char *result, unsigned maxlen)
345{
346 unsigned sz = 0;
347 struct flakey_c *fc = ti->private;
348 unsigned drop_writes;
349
350 switch (type) {
351 case STATUSTYPE_INFO:
352 result[0] = '\0';
353 break;
354
355 case STATUSTYPE_TABLE:
356 DMEMIT("%s %llu %u %u ", fc->dev->name,
357 (unsigned long long)fc->start, fc->up_interval,
358 fc->down_interval);
359
360 drop_writes = test_bit(DROP_WRITES, &fc->flags);
361 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
362
363 if (drop_writes)
364 DMEMIT("drop_writes ");
365
366 if (fc->corrupt_bio_byte)
367 DMEMIT("corrupt_bio_byte %u %c %u %u ",
368 fc->corrupt_bio_byte,
369 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
370 fc->corrupt_bio_value, fc->corrupt_bio_flags);
371
372 break;
373 }
374}
375
376static int flakey_prepare_ioctl(struct dm_target *ti,
377 struct block_device **bdev, fmode_t *mode)
378{
379 struct flakey_c *fc = ti->private;
380
381 *bdev = fc->dev->bdev;
382
383 /*
384 * Only pass ioctls through if the device sizes match exactly.
385 */
386 if (fc->start ||
387 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
388 return 1;
389 return 0;
390}
391
392static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
393{
394 struct flakey_c *fc = ti->private;
395
396 return fn(ti, fc->dev, fc->start, ti->len, data);
397}
398
399static struct target_type flakey_target = {
400 .name = "flakey",
401 .version = {1, 3, 1},
402 .module = THIS_MODULE,
403 .ctr = flakey_ctr,
404 .dtr = flakey_dtr,
405 .map = flakey_map,
406 .end_io = flakey_end_io,
407 .status = flakey_status,
408 .prepare_ioctl = flakey_prepare_ioctl,
409 .iterate_devices = flakey_iterate_devices,
410};
411
412static int __init dm_flakey_init(void)
413{
414 int r = dm_register_target(&flakey_target);
415
416 if (r < 0)
417 DMERR("register failed %d", r);
418
419 return r;
420}
421
422static void __exit dm_flakey_exit(void)
423{
424 dm_unregister_target(&flakey_target);
425}
426
427/* Module hooks */
428module_init(dm_flakey_init);
429module_exit(dm_flakey_exit);
430
431MODULE_DESCRIPTION(DM_NAME " flakey target");
432MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
433MODULE_LICENSE("GPL");