1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2003 Sistina Software (UK) Limited.
4 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
6 * This file is released under the GPL.
9 #include <linux/device-mapper.h>
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>
17 #define DM_MSG_PREFIX "flakey"
19 #define PROBABILITY_BASE 1000000000
21 #define all_corrupt_bio_flags_match(bio, fc) \
22 (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
25 * Flakey: Used for testing only, simulates intermittent,
26 * catastrophic device failure.
30 unsigned long start_time;
32 unsigned int up_interval;
33 unsigned int down_interval;
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;
43 enum feature_flag_bits {
53 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
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"},
68 /* No feature arguments supplied. */
72 r = dm_read_arg_group(_args, as, &argc, &ti->error);
77 arg_name = dm_shift_arg(as);
81 ti->error = "Insufficient feature arguments";
88 if (!strcasecmp(arg_name, "error_reads")) {
89 if (test_and_set_bit(ERROR_READS, &fc->flags)) {
90 ti->error = "Feature error_reads duplicated";
99 if (!strcasecmp(arg_name, "drop_writes")) {
100 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
101 ti->error = "Feature drop_writes duplicated";
103 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
104 ti->error = "Feature drop_writes conflicts with feature error_writes";
114 if (!strcasecmp(arg_name, "error_writes")) {
115 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
116 ti->error = "Feature error_writes duplicated";
119 } else if (test_bit(DROP_WRITES, &fc->flags)) {
120 ti->error = "Feature error_writes conflicts with feature drop_writes";
128 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
130 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
132 ti->error = "Feature corrupt_bio_byte requires parameters";
136 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
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;
150 ti->error = "Invalid corrupt bio direction (r or w)";
156 * Value of byte (0-255) to write in place of correct one.
158 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
164 * Only corrupt bios with these flags set.
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,
178 if (!strcasecmp(arg_name, "random_read_corrupt")) {
180 ti->error = "Feature random_read_corrupt requires a parameter";
183 r = dm_read_arg(_args + 4, as, &fc->random_read_corrupt, &ti->error);
191 if (!strcasecmp(arg_name, "random_write_corrupt")) {
193 ti->error = "Feature random_write_corrupt requires a parameter";
196 r = dm_read_arg(_args + 4, as, &fc->random_write_corrupt, &ti->error);
204 ti->error = "Unrecognised flakey feature requested";
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";
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";
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);
228 * Construct a flakey mapping:
229 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
233 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
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.
239 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
241 static const struct dm_arg _args[] = {
242 {0, UINT_MAX, "Invalid up interval"},
243 {0, UINT_MAX, "Invalid down interval"},
248 unsigned long long tmpll;
249 struct dm_arg_set as;
257 ti->error = "Invalid argument count";
261 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
263 ti->error = "Cannot allocate context";
266 fc->start_time = jiffies;
268 devname = dm_shift_arg(&as);
271 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
272 ti->error = "Invalid device sector";
277 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
281 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
285 if (!(fc->up_interval + fc->down_interval)) {
286 ti->error = "Total (up + down) interval is zero";
291 if (fc->up_interval + fc->down_interval < fc->up_interval) {
292 ti->error = "Interval overflow";
297 r = parse_features(&as, fc, ti);
301 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
303 ti->error = "Device lookup failed";
307 ti->num_flush_bios = 1;
308 ti->num_discard_bios = 1;
309 ti->per_io_data_size = sizeof(struct per_bio_data);
318 static void flakey_dtr(struct dm_target *ti)
320 struct flakey_c *fc = ti->private;
322 dm_put_device(ti, fc->dev);
326 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
328 struct flakey_c *fc = ti->private;
330 return fc->start + dm_target_offset(ti, bi_sector);
333 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
335 struct flakey_c *fc = ti->private;
337 bio_set_dev(bio, fc->dev->bdev);
338 bio->bi_iter.bi_sector = flakey_map_sector(ti, bio->bi_iter.bi_sector);
341 static void corrupt_bio_common(struct bio *bio, unsigned int corrupt_bio_byte,
342 unsigned char corrupt_bio_value)
344 struct bvec_iter iter;
348 * Overwrite the Nth byte of the bio's data, on whichever page
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);
364 corrupt_bio_byte -= bio_iter_len(bio, iter);
368 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
370 unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
372 if (!bio_has_data(bio))
375 corrupt_bio_common(bio, corrupt_bio_byte, fc->corrupt_bio_value);
378 static void corrupt_bio_random(struct bio *bio)
380 unsigned int corrupt_byte;
381 unsigned char corrupt_value;
383 if (!bio_has_data(bio))
386 corrupt_byte = get_random_u32() % bio->bi_iter.bi_size;
387 corrupt_value = get_random_u8();
389 corrupt_bio_common(bio, corrupt_byte, corrupt_value);
392 static void clone_free(struct bio *clone)
394 struct folio_iter fi;
396 if (clone->bi_vcnt > 0) { /* bio_for_each_folio_all crashes with an empty bio */
397 bio_for_each_folio_all(fi, clone)
405 static void clone_endio(struct bio *clone)
407 struct bio *bio = clone->bi_private;
408 bio->bi_status = clone->bi_status;
413 static struct bio *clone_bio(struct dm_target *ti, struct flakey_c *fc, struct bio *bio)
416 unsigned size, remaining_size, nr_iovecs, order;
417 struct bvec_iter iter = bio->bi_iter;
419 if (unlikely(bio->bi_iter.bi_size > UIO_MAXIOV << PAGE_SHIFT))
420 dm_accept_partial_bio(bio, UIO_MAXIOV << PAGE_SHIFT >> SECTOR_SHIFT);
422 size = bio->bi_iter.bi_size;
423 nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
425 clone = bio_kmalloc(nr_iovecs, GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN);
429 bio_init(clone, fc->dev->bdev, bio->bi_inline_vecs, nr_iovecs, bio->bi_opf);
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;
435 remaining_size = size;
437 order = MAX_PAGE_ORDER;
438 while (remaining_size) {
440 unsigned size_to_add, to_copy;
442 unsigned remaining_order = __fls((remaining_size + PAGE_SIZE - 1) >> PAGE_SHIFT);
443 order = min(order, remaining_order);
446 pages = alloc_pages(GFP_NOIO | __GFP_NORETRY | __GFP_NOWARN | __GFP_COMP, order);
447 if (unlikely(!pages)) {
450 goto retry_alloc_pages;
455 size_to_add = min((unsigned)PAGE_SIZE << order, remaining_size);
457 virt = page_to_virt(pages);
458 to_copy = size_to_add;
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);
466 bvec_iter_advance(bio->bi_io_vec, &iter, this_step);
467 to_copy -= this_step;
471 __bio_add_page(clone, pages, size_to_add, 0);
472 remaining_size -= size_to_add;
478 static int flakey_map(struct dm_target *ti, struct bio *bio)
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));
484 pb->bio_submitted = false;
486 if (op_is_zone_mgmt(bio_op(bio)))
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;
494 * Flag this bio as submitted while down.
496 pb->bio_submitted = true;
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.
502 if (bio_data_dir(bio) == READ) {
503 if (test_bit(ERROR_READS, &fc->flags))
504 return DM_MAPIO_KILL;
509 * Drop or error writes?
511 if (test_bit(DROP_WRITES, &fc->flags)) {
513 return DM_MAPIO_SUBMITTED;
514 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
516 return DM_MAPIO_SUBMITTED;
520 * Corrupt matching writes.
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;
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;
534 if (corrupt_fixed || corrupt_random) {
535 struct bio *clone = clone_bio(ti, fc, bio);
538 corrupt_bio_data(clone, fc);
540 corrupt_bio_random(clone);
542 return DM_MAPIO_SUBMITTED;
548 flakey_map_bio(ti, bio);
550 return DM_MAPIO_REMAPPED;
553 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
556 struct flakey_c *fc = ti->private;
557 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
559 if (op_is_zone_mgmt(bio_op(bio)))
560 return DM_ENDIO_DONE;
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)) {
567 * Corrupt successful matching READs while in down state.
569 corrupt_bio_data(bio, fc);
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);
578 if (test_bit(ERROR_READS, &fc->flags)) {
580 * Error read during the down_interval if drop_writes
581 * and error_writes were not configured.
583 *error = BLK_STS_IOERR;
587 return DM_ENDIO_DONE;
590 static void flakey_status(struct dm_target *ti, status_type_t type,
591 unsigned int status_flags, char *result, unsigned int maxlen)
594 struct flakey_c *fc = ti->private;
595 unsigned int error_reads, drop_writes, error_writes;
598 case STATUSTYPE_INFO:
602 case STATUSTYPE_TABLE:
603 DMEMIT("%s %llu %u %u", fc->dev->name,
604 (unsigned long long)fc->start, fc->up_interval,
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);
616 DMEMIT(" error_reads");
618 DMEMIT(" drop_writes");
619 else if (error_writes)
620 DMEMIT(" error_writes");
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);
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);
641 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
643 struct flakey_c *fc = ti->private;
645 *bdev = fc->dev->bdev;
648 * Only pass ioctls through if the device sizes match exactly.
650 if (fc->start || ti->len != bdev_nr_sectors((*bdev)))
655 #ifdef CONFIG_BLK_DEV_ZONED
656 static int flakey_report_zones(struct dm_target *ti,
657 struct dm_report_zones_args *args, unsigned int nr_zones)
659 struct flakey_c *fc = ti->private;
661 return dm_report_zones(fc->dev->bdev, fc->start,
662 flakey_map_sector(ti, args->next_sector),
666 #define flakey_report_zones NULL
669 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
671 struct flakey_c *fc = ti->private;
673 return fn(ti, fc->dev, fc->start, ti->len, data);
676 static struct target_type flakey_target = {
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,
685 .end_io = flakey_end_io,
686 .status = flakey_status,
687 .prepare_ioctl = flakey_prepare_ioctl,
688 .iterate_devices = flakey_iterate_devices,
692 MODULE_DESCRIPTION(DM_NAME " flakey target");
693 MODULE_AUTHOR("Joe Thornber <dm-devel@lists.linux.dev>");
694 MODULE_LICENSE("GPL");