GNU Linux-libre 4.19.264-gnu1
[releases.git] / drivers / md / dm-flakey.c
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
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 (!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  */
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
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
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
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) || 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
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 = (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
318 static 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         /* We need to remap reported zones, so remember the BIO iter */
330         if (bio_op(bio) == REQ_OP_ZONE_REPORT)
331                 goto map_bio;
332
333         /* Are we alive ? */
334         elapsed = (jiffies - fc->start_time) / HZ;
335         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
336                 /*
337                  * Flag this bio as submitted while down.
338                  */
339                 pb->bio_submitted = true;
340
341                 /*
342                  * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
343                  * Otherwise, flakey_end_io() will decide if the reads should be modified.
344                  */
345                 if (bio_data_dir(bio) == READ) {
346                         if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
347                             !test_bit(ERROR_WRITES, &fc->flags))
348                                 return DM_MAPIO_KILL;
349                         goto map_bio;
350                 }
351
352                 /*
353                  * Drop or error writes?
354                  */
355                 if (test_bit(DROP_WRITES, &fc->flags)) {
356                         bio_endio(bio);
357                         return DM_MAPIO_SUBMITTED;
358                 }
359                 else if (test_bit(ERROR_WRITES, &fc->flags)) {
360                         bio_io_error(bio);
361                         return DM_MAPIO_SUBMITTED;
362                 }
363
364                 /*
365                  * Corrupt matching writes.
366                  */
367                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
368                         if (all_corrupt_bio_flags_match(bio, fc))
369                                 corrupt_bio_data(bio, fc);
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
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 (bio_op(bio) == REQ_OP_ZONE_RESET)
392                 return DM_ENDIO_DONE;
393
394         if (bio_op(bio) == REQ_OP_ZONE_REPORT) {
395                 dm_remap_zone_report(ti, bio, fc->start);
396                 return DM_ENDIO_DONE;
397         }
398
399         if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
400                 if (fc->corrupt_bio_byte && (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
420 static void flakey_status(struct dm_target *ti, status_type_t type,
421                           unsigned status_flags, char *result, unsigned maxlen)
422 {
423         unsigned sz = 0;
424         struct flakey_c *fc = ti->private;
425         unsigned 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 }
455
456 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
457 {
458         struct flakey_c *fc = ti->private;
459
460         *bdev = fc->dev->bdev;
461
462         /*
463          * Only pass ioctls through if the device sizes match exactly.
464          */
465         if (fc->start ||
466             ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
467                 return 1;
468         return 0;
469 }
470
471 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
472 {
473         struct flakey_c *fc = ti->private;
474
475         return fn(ti, fc->dev, fc->start, ti->len, data);
476 }
477
478 static struct target_type flakey_target = {
479         .name   = "flakey",
480         .version = {1, 5, 0},
481 #ifdef CONFIG_BLK_DEV_ZONED
482         .features = DM_TARGET_ZONED_HM,
483 #endif
484         .module = THIS_MODULE,
485         .ctr    = flakey_ctr,
486         .dtr    = flakey_dtr,
487         .map    = flakey_map,
488         .end_io = flakey_end_io,
489         .status = flakey_status,
490         .prepare_ioctl = flakey_prepare_ioctl,
491         .iterate_devices = flakey_iterate_devices,
492 };
493
494 static int __init dm_flakey_init(void)
495 {
496         int r = dm_register_target(&flakey_target);
497
498         if (r < 0)
499                 DMERR("register failed %d", r);
500
501         return r;
502 }
503
504 static void __exit dm_flakey_exit(void)
505 {
506         dm_unregister_target(&flakey_target);
507 }
508
509 /* Module hooks */
510 module_init(dm_flakey_init);
511 module_exit(dm_flakey_exit);
512
513 MODULE_DESCRIPTION(DM_NAME " flakey target");
514 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
515 MODULE_LICENSE("GPL");