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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 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                 /*
74                  * drop_writes
75                  */
76                 if (!strcasecmp(arg_name, "drop_writes")) {
77                         if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
78                                 ti->error = "Feature drop_writes duplicated";
79                                 return -EINVAL;
80                         } else if (test_bit(ERROR_WRITES, &fc->flags)) {
81                                 ti->error = "Feature drop_writes conflicts with feature error_writes";
82                                 return -EINVAL;
83                         }
84
85                         continue;
86                 }
87
88                 /*
89                  * error_writes
90                  */
91                 if (!strcasecmp(arg_name, "error_writes")) {
92                         if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
93                                 ti->error = "Feature error_writes duplicated";
94                                 return -EINVAL;
95
96                         } else if (test_bit(DROP_WRITES, &fc->flags)) {
97                                 ti->error = "Feature error_writes conflicts with feature drop_writes";
98                                 return -EINVAL;
99                         }
100
101                         continue;
102                 }
103
104                 /*
105                  * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
106                  */
107                 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
108                         if (!argc) {
109                                 ti->error = "Feature corrupt_bio_byte requires parameters";
110                                 return -EINVAL;
111                         }
112
113                         r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
114                         if (r)
115                                 return r;
116                         argc--;
117
118                         /*
119                          * Direction r or w?
120                          */
121                         arg_name = dm_shift_arg(as);
122                         if (!strcasecmp(arg_name, "w"))
123                                 fc->corrupt_bio_rw = WRITE;
124                         else if (!strcasecmp(arg_name, "r"))
125                                 fc->corrupt_bio_rw = READ;
126                         else {
127                                 ti->error = "Invalid corrupt bio direction (r or w)";
128                                 return -EINVAL;
129                         }
130                         argc--;
131
132                         /*
133                          * Value of byte (0-255) to write in place of correct one.
134                          */
135                         r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
136                         if (r)
137                                 return r;
138                         argc--;
139
140                         /*
141                          * Only corrupt bios with these flags set.
142                          */
143                         r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
144                         if (r)
145                                 return r;
146                         argc--;
147
148                         continue;
149                 }
150
151                 ti->error = "Unrecognised flakey feature requested";
152                 return -EINVAL;
153         }
154
155         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
156                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
157                 return -EINVAL;
158
159         } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
160                 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
161                 return -EINVAL;
162         }
163
164         return 0;
165 }
166
167 /*
168  * Construct a flakey mapping:
169  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
170  *
171  *   Feature args:
172  *     [drop_writes]
173  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
174  *
175  *   Nth_byte starts from 1 for the first byte.
176  *   Direction is r for READ or w for WRITE.
177  *   bio_flags is ignored if 0.
178  */
179 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
180 {
181         static struct dm_arg _args[] = {
182                 {0, UINT_MAX, "Invalid up interval"},
183                 {0, UINT_MAX, "Invalid down interval"},
184         };
185
186         int r;
187         struct flakey_c *fc;
188         unsigned long long tmpll;
189         struct dm_arg_set as;
190         const char *devname;
191         char dummy;
192
193         as.argc = argc;
194         as.argv = argv;
195
196         if (argc < 4) {
197                 ti->error = "Invalid argument count";
198                 return -EINVAL;
199         }
200
201         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
202         if (!fc) {
203                 ti->error = "Cannot allocate context";
204                 return -ENOMEM;
205         }
206         fc->start_time = jiffies;
207
208         devname = dm_shift_arg(&as);
209
210         r = -EINVAL;
211         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
212                 ti->error = "Invalid device sector";
213                 goto bad;
214         }
215         fc->start = tmpll;
216
217         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
218         if (r)
219                 goto bad;
220
221         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
222         if (r)
223                 goto bad;
224
225         if (!(fc->up_interval + fc->down_interval)) {
226                 ti->error = "Total (up + down) interval is zero";
227                 r = -EINVAL;
228                 goto bad;
229         }
230
231         if (fc->up_interval + fc->down_interval < fc->up_interval) {
232                 ti->error = "Interval overflow";
233                 r = -EINVAL;
234                 goto bad;
235         }
236
237         r = parse_features(&as, fc, ti);
238         if (r)
239                 goto bad;
240
241         r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
242         if (r) {
243                 ti->error = "Device lookup failed";
244                 goto bad;
245         }
246
247         ti->num_flush_bios = 1;
248         ti->num_discard_bios = 1;
249         ti->per_io_data_size = sizeof(struct per_bio_data);
250         ti->private = fc;
251         return 0;
252
253 bad:
254         kfree(fc);
255         return r;
256 }
257
258 static void flakey_dtr(struct dm_target *ti)
259 {
260         struct flakey_c *fc = ti->private;
261
262         dm_put_device(ti, fc->dev);
263         kfree(fc);
264 }
265
266 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
267 {
268         struct flakey_c *fc = ti->private;
269
270         return fc->start + dm_target_offset(ti, bi_sector);
271 }
272
273 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
274 {
275         struct flakey_c *fc = ti->private;
276
277         bio->bi_bdev = fc->dev->bdev;
278         if (bio_sectors(bio))
279                 bio->bi_iter.bi_sector =
280                         flakey_map_sector(ti, bio->bi_iter.bi_sector);
281 }
282
283 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
284 {
285         unsigned bio_bytes = bio_cur_bytes(bio);
286         char *data = bio_data(bio);
287
288         /*
289          * Overwrite the Nth byte of the data returned.
290          */
291         if (data && bio_bytes >= fc->corrupt_bio_byte) {
292                 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
293
294                 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
295                         "(rw=%c bi_opf=%u bi_sector=%llu cur_bytes=%u)\n",
296                         bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
297                         (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
298                         (unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
299         }
300 }
301
302 static int flakey_map(struct dm_target *ti, struct bio *bio)
303 {
304         struct flakey_c *fc = ti->private;
305         unsigned elapsed;
306         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
307         pb->bio_submitted = false;
308
309         /* Are we alive ? */
310         elapsed = (jiffies - fc->start_time) / HZ;
311         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
312                 /*
313                  * Flag this bio as submitted while down.
314                  */
315                 pb->bio_submitted = true;
316
317                 /*
318                  * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
319                  * Otherwise, flakey_end_io() will decide if the reads should be modified.
320                  */
321                 if (bio_data_dir(bio) == READ) {
322                         if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
323                             !test_bit(ERROR_WRITES, &fc->flags))
324                                 return DM_MAPIO_KILL;
325                         goto map_bio;
326                 }
327
328                 /*
329                  * Drop or error writes?
330                  */
331                 if (test_bit(DROP_WRITES, &fc->flags)) {
332                         bio_endio(bio);
333                         return DM_MAPIO_SUBMITTED;
334                 }
335                 else if (test_bit(ERROR_WRITES, &fc->flags)) {
336                         bio_io_error(bio);
337                         return DM_MAPIO_SUBMITTED;
338                 }
339
340                 /*
341                  * Corrupt matching writes.
342                  */
343                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
344                         if (all_corrupt_bio_flags_match(bio, fc))
345                                 corrupt_bio_data(bio, fc);
346                         goto map_bio;
347                 }
348
349                 /*
350                  * By default, error all I/O.
351                  */
352                 return DM_MAPIO_KILL;
353         }
354
355 map_bio:
356         flakey_map_bio(ti, bio);
357
358         return DM_MAPIO_REMAPPED;
359 }
360
361 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
362                 blk_status_t *error)
363 {
364         struct flakey_c *fc = ti->private;
365         struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
366
367         if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
368                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
369                     all_corrupt_bio_flags_match(bio, fc)) {
370                         /*
371                          * Corrupt successful matching READs while in down state.
372                          */
373                         corrupt_bio_data(bio, fc);
374
375                 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
376                            !test_bit(ERROR_WRITES, &fc->flags)) {
377                         /*
378                          * Error read during the down_interval if drop_writes
379                          * and error_writes were not configured.
380                          */
381                         *error = BLK_STS_IOERR;
382                 }
383         }
384
385         return DM_ENDIO_DONE;
386 }
387
388 static void flakey_status(struct dm_target *ti, status_type_t type,
389                           unsigned status_flags, char *result, unsigned maxlen)
390 {
391         unsigned sz = 0;
392         struct flakey_c *fc = ti->private;
393         unsigned drop_writes, error_writes;
394
395         switch (type) {
396         case STATUSTYPE_INFO:
397                 result[0] = '\0';
398                 break;
399
400         case STATUSTYPE_TABLE:
401                 DMEMIT("%s %llu %u %u ", fc->dev->name,
402                        (unsigned long long)fc->start, fc->up_interval,
403                        fc->down_interval);
404
405                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
406                 error_writes = test_bit(ERROR_WRITES, &fc->flags);
407                 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
408
409                 if (drop_writes)
410                         DMEMIT("drop_writes ");
411                 else if (error_writes)
412                         DMEMIT("error_writes ");
413
414                 if (fc->corrupt_bio_byte)
415                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
416                                fc->corrupt_bio_byte,
417                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
418                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
419
420                 break;
421         }
422 }
423
424 static int flakey_prepare_ioctl(struct dm_target *ti,
425                 struct block_device **bdev, fmode_t *mode)
426 {
427         struct flakey_c *fc = ti->private;
428
429         *bdev = fc->dev->bdev;
430
431         /*
432          * Only pass ioctls through if the device sizes match exactly.
433          */
434         if (fc->start ||
435             ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
436                 return 1;
437         return 0;
438 }
439
440 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
441 {
442         struct flakey_c *fc = ti->private;
443
444         return fn(ti, fc->dev, fc->start, ti->len, data);
445 }
446
447 static struct target_type flakey_target = {
448         .name   = "flakey",
449         .version = {1, 4, 0},
450         .module = THIS_MODULE,
451         .ctr    = flakey_ctr,
452         .dtr    = flakey_dtr,
453         .map    = flakey_map,
454         .end_io = flakey_end_io,
455         .status = flakey_status,
456         .prepare_ioctl = flakey_prepare_ioctl,
457         .iterate_devices = flakey_iterate_devices,
458 };
459
460 static int __init dm_flakey_init(void)
461 {
462         int r = dm_register_target(&flakey_target);
463
464         if (r < 0)
465                 DMERR("register failed %d", r);
466
467         return r;
468 }
469
470 static void __exit dm_flakey_exit(void)
471 {
472         dm_unregister_target(&flakey_target);
473 }
474
475 /* Module hooks */
476 module_init(dm_flakey_init);
477 module_exit(dm_flakey_exit);
478
479 MODULE_DESCRIPTION(DM_NAME " flakey target");
480 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
481 MODULE_LICENSE("GPL");