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) || bio_op(bio) == REQ_OP_ZONE_RESET)
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 /* Do not fail reset zone */
326 if (bio_op(bio) == REQ_OP_ZONE_RESET)
327 goto map_bio;
328
329 /* Are we alive ? */
330 elapsed = (jiffies - fc->start_time) / HZ;
331 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
332 /*
333 * Flag this bio as submitted while down.
334 */
335 pb->bio_submitted = true;
336
337 /*
338 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
339 * Otherwise, flakey_end_io() will decide if the reads should be modified.
340 */
341 if (bio_data_dir(bio) == READ) {
342 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
343 !test_bit(ERROR_WRITES, &fc->flags))
344 return DM_MAPIO_KILL;
345 goto map_bio;
346 }
347
348 /*
349 * Drop or error writes?
350 */
351 if (test_bit(DROP_WRITES, &fc->flags)) {
352 bio_endio(bio);
353 return DM_MAPIO_SUBMITTED;
354 }
355 else if (test_bit(ERROR_WRITES, &fc->flags)) {
356 bio_io_error(bio);
357 return DM_MAPIO_SUBMITTED;
358 }
359
360 /*
361 * Corrupt matching writes.
362 */
363 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
364 if (all_corrupt_bio_flags_match(bio, fc))
365 corrupt_bio_data(bio, fc);
366 goto map_bio;
367 }
368
369 /*
370 * By default, error all I/O.
371 */
372 return DM_MAPIO_KILL;
373 }
374
375map_bio:
376 flakey_map_bio(ti, bio);
377
378 return DM_MAPIO_REMAPPED;
379}
380
381static int flakey_end_io(struct dm_target *ti, struct bio *bio,
382 blk_status_t *error)
383{
384 struct flakey_c *fc = ti->private;
385 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
386
387 if (bio_op(bio) == REQ_OP_ZONE_RESET)
388 return DM_ENDIO_DONE;
389
390 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
391 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
392 all_corrupt_bio_flags_match(bio, fc)) {
393 /*
394 * Corrupt successful matching READs while in down state.
395 */
396 corrupt_bio_data(bio, fc);
397
398 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
399 !test_bit(ERROR_WRITES, &fc->flags)) {
400 /*
401 * Error read during the down_interval if drop_writes
402 * and error_writes were not configured.
403 */
404 *error = BLK_STS_IOERR;
405 }
406 }
407
408 return DM_ENDIO_DONE;
409}
410
411static void flakey_status(struct dm_target *ti, status_type_t type,
412 unsigned status_flags, char *result, unsigned maxlen)
413{
414 unsigned sz = 0;
415 struct flakey_c *fc = ti->private;
416 unsigned drop_writes, error_writes;
417
418 switch (type) {
419 case STATUSTYPE_INFO:
420 result[0] = '\0';
421 break;
422
423 case STATUSTYPE_TABLE:
424 DMEMIT("%s %llu %u %u ", fc->dev->name,
425 (unsigned long long)fc->start, fc->up_interval,
426 fc->down_interval);
427
428 drop_writes = test_bit(DROP_WRITES, &fc->flags);
429 error_writes = test_bit(ERROR_WRITES, &fc->flags);
430 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
431
432 if (drop_writes)
433 DMEMIT("drop_writes ");
434 else if (error_writes)
435 DMEMIT("error_writes ");
436
437 if (fc->corrupt_bio_byte)
438 DMEMIT("corrupt_bio_byte %u %c %u %u ",
439 fc->corrupt_bio_byte,
440 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
441 fc->corrupt_bio_value, fc->corrupt_bio_flags);
442
443 break;
444 }
445}
446
447static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
448{
449 struct flakey_c *fc = ti->private;
450
451 *bdev = fc->dev->bdev;
452
453 /*
454 * Only pass ioctls through if the device sizes match exactly.
455 */
456 if (fc->start ||
457 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
458 return 1;
459 return 0;
460}
461
462#ifdef CONFIG_BLK_DEV_ZONED
463static int flakey_report_zones(struct dm_target *ti, sector_t sector,
464 struct blk_zone *zones, unsigned int *nr_zones,
465 gfp_t gfp_mask)
466{
467 struct flakey_c *fc = ti->private;
468 int ret;
469
470 /* Do report and remap it */
471 ret = blkdev_report_zones(fc->dev->bdev, flakey_map_sector(ti, sector),
472 zones, nr_zones, gfp_mask);
473 if (ret != 0)
474 return ret;
475
476 if (*nr_zones)
477 dm_remap_zone_report(ti, fc->start, zones, nr_zones);
478 return 0;
479}
480#endif
481
482static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
483{
484 struct flakey_c *fc = ti->private;
485
486 return fn(ti, fc->dev, fc->start, ti->len, data);
487}
488
489static struct target_type flakey_target = {
490 .name = "flakey",
491 .version = {1, 5, 0},
492#ifdef CONFIG_BLK_DEV_ZONED
493 .features = DM_TARGET_ZONED_HM,
494 .report_zones = flakey_report_zones,
495#endif
496 .module = THIS_MODULE,
497 .ctr = flakey_ctr,
498 .dtr = flakey_dtr,
499 .map = flakey_map,
500 .end_io = flakey_end_io,
501 .status = flakey_status,
502 .prepare_ioctl = flakey_prepare_ioctl,
503 .iterate_devices = flakey_iterate_devices,
504};
505
506static int __init dm_flakey_init(void)
507{
508 int r = dm_register_target(&flakey_target);
509
510 if (r < 0)
511 DMERR("register failed %d", r);
512
513 return r;
514}
515
516static void __exit dm_flakey_exit(void)
517{
518 dm_unregister_target(&flakey_target);
519}
520
521/* Module hooks */
522module_init(dm_flakey_init);
523module_exit(dm_flakey_exit);
524
525MODULE_DESCRIPTION(DM_NAME " flakey target");
526MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
527MODULE_LICENSE("GPL");
528