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 */
25 struct 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
38 enum feature_flag_bits {
39 DROP_WRITES,
40 ERROR_WRITES
41 };
42
43 struct per_bio_data {
44 bool bio_submitted;
45 };
46
parse_features(struct dm_arg_set * as,struct flakey_c * fc,struct dm_target * ti)47 static 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 (arg_name && !strcasecmp(arg_name, "w"))
128 fc->corrupt_bio_rw = WRITE;
129 else if (arg_name && !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 */
flakey_ctr(struct dm_target * ti,unsigned int argc,char ** argv)184 static 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
258 bad:
259 kfree(fc);
260 return r;
261 }
262
flakey_dtr(struct dm_target * ti)263 static 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
flakey_map_sector(struct dm_target * ti,sector_t bi_sector)271 static 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
flakey_map_bio(struct dm_target * ti,struct bio * bio)278 static 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
corrupt_bio_data(struct bio * bio,struct flakey_c * fc)288 static 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;
305 struct page *page = bio_iter_page(bio, iter);
306 if (unlikely(page == ZERO_PAGE(0)))
307 break;
308 segment = (page_address(page) + bio_iter_offset(bio, iter));
309 segment[corrupt_bio_byte] = fc->corrupt_bio_value;
310 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
311 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
312 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
313 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
314 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
315 break;
316 }
317 corrupt_bio_byte -= bio_iter_len(bio, iter);
318 }
319 }
320
flakey_map(struct dm_target * ti,struct bio * bio)321 static int flakey_map(struct dm_target *ti, struct bio *bio)
322 {
323 struct flakey_c *fc = ti->private;
324 unsigned elapsed;
325 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
326 pb->bio_submitted = false;
327
328 if (op_is_zone_mgmt(bio_op(bio)))
329 goto map_bio;
330
331 /* Are we alive ? */
332 elapsed = (jiffies - fc->start_time) / HZ;
333 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
334 /*
335 * Flag this bio as submitted while down.
336 */
337 pb->bio_submitted = true;
338
339 /*
340 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
341 * Otherwise, flakey_end_io() will decide if the reads should be modified.
342 */
343 if (bio_data_dir(bio) == READ) {
344 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
345 !test_bit(ERROR_WRITES, &fc->flags))
346 return DM_MAPIO_KILL;
347 goto map_bio;
348 }
349
350 /*
351 * Drop or error writes?
352 */
353 if (test_bit(DROP_WRITES, &fc->flags)) {
354 bio_endio(bio);
355 return DM_MAPIO_SUBMITTED;
356 }
357 else if (test_bit(ERROR_WRITES, &fc->flags)) {
358 bio_io_error(bio);
359 return DM_MAPIO_SUBMITTED;
360 }
361
362 /*
363 * Corrupt matching writes.
364 */
365 if (fc->corrupt_bio_byte) {
366 if (fc->corrupt_bio_rw == WRITE) {
367 if (all_corrupt_bio_flags_match(bio, fc))
368 corrupt_bio_data(bio, fc);
369 }
370 goto map_bio;
371 }
372
373 /*
374 * By default, error all I/O.
375 */
376 return DM_MAPIO_KILL;
377 }
378
379 map_bio:
380 flakey_map_bio(ti, bio);
381
382 return DM_MAPIO_REMAPPED;
383 }
384
flakey_end_io(struct dm_target * ti,struct bio * bio,blk_status_t * error)385 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
386 blk_status_t *error)
387 {
388 struct flakey_c *fc = ti->private;
389 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
390
391 if (op_is_zone_mgmt(bio_op(bio)))
392 return DM_ENDIO_DONE;
393
394 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
395 if (fc->corrupt_bio_byte) {
396 if ((fc->corrupt_bio_rw == READ) &&
397 all_corrupt_bio_flags_match(bio, fc)) {
398 /*
399 * Corrupt successful matching READs while in down state.
400 */
401 corrupt_bio_data(bio, fc);
402 }
403 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
404 !test_bit(ERROR_WRITES, &fc->flags)) {
405 /*
406 * Error read during the down_interval if drop_writes
407 * and error_writes were not configured.
408 */
409 *error = BLK_STS_IOERR;
410 }
411 }
412
413 return DM_ENDIO_DONE;
414 }
415
flakey_status(struct dm_target * ti,status_type_t type,unsigned status_flags,char * result,unsigned maxlen)416 static void flakey_status(struct dm_target *ti, status_type_t type,
417 unsigned status_flags, char *result, unsigned maxlen)
418 {
419 unsigned sz = 0;
420 struct flakey_c *fc = ti->private;
421 unsigned drop_writes, error_writes;
422
423 switch (type) {
424 case STATUSTYPE_INFO:
425 result[0] = '\0';
426 break;
427
428 case STATUSTYPE_TABLE:
429 DMEMIT("%s %llu %u %u ", fc->dev->name,
430 (unsigned long long)fc->start, fc->up_interval,
431 fc->down_interval);
432
433 drop_writes = test_bit(DROP_WRITES, &fc->flags);
434 error_writes = test_bit(ERROR_WRITES, &fc->flags);
435 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
436
437 if (drop_writes)
438 DMEMIT("drop_writes ");
439 else if (error_writes)
440 DMEMIT("error_writes ");
441
442 if (fc->corrupt_bio_byte)
443 DMEMIT("corrupt_bio_byte %u %c %u %u ",
444 fc->corrupt_bio_byte,
445 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
446 fc->corrupt_bio_value, fc->corrupt_bio_flags);
447
448 break;
449 }
450 }
451
flakey_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev)452 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
453 {
454 struct flakey_c *fc = ti->private;
455
456 *bdev = fc->dev->bdev;
457
458 /*
459 * Only pass ioctls through if the device sizes match exactly.
460 */
461 if (fc->start ||
462 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
463 return 1;
464 return 0;
465 }
466
467 #ifdef CONFIG_BLK_DEV_ZONED
flakey_report_zones(struct dm_target * ti,struct dm_report_zones_args * args,unsigned int nr_zones)468 static int flakey_report_zones(struct dm_target *ti,
469 struct dm_report_zones_args *args, unsigned int nr_zones)
470 {
471 struct flakey_c *fc = ti->private;
472 sector_t sector = flakey_map_sector(ti, args->next_sector);
473
474 args->start = fc->start;
475 return blkdev_report_zones(fc->dev->bdev, sector, nr_zones,
476 dm_report_zones_cb, args);
477 }
478 #endif
479
flakey_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)480 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
481 {
482 struct flakey_c *fc = ti->private;
483
484 return fn(ti, fc->dev, fc->start, ti->len, data);
485 }
486
487 static struct target_type flakey_target = {
488 .name = "flakey",
489 .version = {1, 5, 0},
490 #ifdef CONFIG_BLK_DEV_ZONED
491 .features = DM_TARGET_ZONED_HM,
492 .report_zones = flakey_report_zones,
493 #endif
494 .module = THIS_MODULE,
495 .ctr = flakey_ctr,
496 .dtr = flakey_dtr,
497 .map = flakey_map,
498 .end_io = flakey_end_io,
499 .status = flakey_status,
500 .prepare_ioctl = flakey_prepare_ioctl,
501 .iterate_devices = flakey_iterate_devices,
502 };
503
dm_flakey_init(void)504 static int __init dm_flakey_init(void)
505 {
506 int r = dm_register_target(&flakey_target);
507
508 if (r < 0)
509 DMERR("register failed %d", r);
510
511 return r;
512 }
513
dm_flakey_exit(void)514 static void __exit dm_flakey_exit(void)
515 {
516 dm_unregister_target(&flakey_target);
517 }
518
519 /* Module hooks */
520 module_init(dm_flakey_init);
521 module_exit(dm_flakey_exit);
522
523 MODULE_DESCRIPTION(DM_NAME " flakey target");
524 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
525 MODULE_LICENSE("GPL");
526