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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_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
20
21
22
23
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};
41
42struct per_bio_data {
43 bool bio_submitted;
44};
45
46static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
47 struct dm_target *ti)
48{
49 int r;
50 unsigned argc;
51 const char *arg_name;
52
53 static struct dm_arg _args[] = {
54 {0, 6, "Invalid number of feature args"},
55 {1, UINT_MAX, "Invalid corrupt bio byte"},
56 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
57 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
58 };
59
60
61 if (!as->argc)
62 return 0;
63
64 r = dm_read_arg_group(_args, as, &argc, &ti->error);
65 if (r)
66 return r;
67
68 while (argc) {
69 arg_name = dm_shift_arg(as);
70 argc--;
71
72
73
74
75 if (!strcasecmp(arg_name, "drop_writes")) {
76 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
77 ti->error = "Feature drop_writes duplicated";
78 return -EINVAL;
79 }
80
81 continue;
82 }
83
84
85
86
87 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
88 if (!argc) {
89 ti->error = "Feature corrupt_bio_byte requires parameters";
90 return -EINVAL;
91 }
92
93 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
94 if (r)
95 return r;
96 argc--;
97
98
99
100
101 arg_name = dm_shift_arg(as);
102 if (!strcasecmp(arg_name, "w"))
103 fc->corrupt_bio_rw = WRITE;
104 else if (!strcasecmp(arg_name, "r"))
105 fc->corrupt_bio_rw = READ;
106 else {
107 ti->error = "Invalid corrupt bio direction (r or w)";
108 return -EINVAL;
109 }
110 argc--;
111
112
113
114
115 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
116 if (r)
117 return r;
118 argc--;
119
120
121
122
123 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
124 if (r)
125 return r;
126 argc--;
127
128 continue;
129 }
130
131 ti->error = "Unrecognised flakey feature requested";
132 return -EINVAL;
133 }
134
135 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
136 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
137 return -EINVAL;
138 }
139
140 return 0;
141}
142
143
144
145
146
147
148
149
150
151
152
153
154
155static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
156{
157 static struct dm_arg _args[] = {
158 {0, UINT_MAX, "Invalid up interval"},
159 {0, UINT_MAX, "Invalid down interval"},
160 };
161
162 int r;
163 struct flakey_c *fc;
164 unsigned long long tmpll;
165 struct dm_arg_set as;
166 const char *devname;
167 char dummy;
168
169 as.argc = argc;
170 as.argv = argv;
171
172 if (argc < 4) {
173 ti->error = "Invalid argument count";
174 return -EINVAL;
175 }
176
177 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
178 if (!fc) {
179 ti->error = "Cannot allocate context";
180 return -ENOMEM;
181 }
182 fc->start_time = jiffies;
183
184 devname = dm_shift_arg(&as);
185
186 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
187 ti->error = "Invalid device sector";
188 goto bad;
189 }
190 fc->start = tmpll;
191
192 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
193 if (r)
194 goto bad;
195
196 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
197 if (r)
198 goto bad;
199
200 if (!(fc->up_interval + fc->down_interval)) {
201 ti->error = "Total (up + down) interval is zero";
202 goto bad;
203 }
204
205 if (fc->up_interval + fc->down_interval < fc->up_interval) {
206 ti->error = "Interval overflow";
207 goto bad;
208 }
209
210 r = parse_features(&as, fc, ti);
211 if (r)
212 goto bad;
213
214 if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
215 ti->error = "Device lookup failed";
216 goto bad;
217 }
218
219 ti->num_flush_bios = 1;
220 ti->num_discard_bios = 1;
221 ti->per_bio_data_size = sizeof(struct per_bio_data);
222 ti->private = fc;
223 return 0;
224
225bad:
226 kfree(fc);
227 return -EINVAL;
228}
229
230static void flakey_dtr(struct dm_target *ti)
231{
232 struct flakey_c *fc = ti->private;
233
234 dm_put_device(ti, fc->dev);
235 kfree(fc);
236}
237
238static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
239{
240 struct flakey_c *fc = ti->private;
241
242 return fc->start + dm_target_offset(ti, bi_sector);
243}
244
245static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
246{
247 struct flakey_c *fc = ti->private;
248
249 bio->bi_bdev = fc->dev->bdev;
250 if (bio_sectors(bio))
251 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
252}
253
254static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
255{
256 unsigned bio_bytes = bio_cur_bytes(bio);
257 char *data = bio_data(bio);
258
259
260
261
262 if (data && bio_bytes >= fc->corrupt_bio_byte) {
263 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
264
265 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
266 "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
267 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
268 (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
269 bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
270 }
271}
272
273static int flakey_map(struct dm_target *ti, struct bio *bio)
274{
275 struct flakey_c *fc = ti->private;
276 unsigned elapsed;
277 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
278 pb->bio_submitted = false;
279
280
281 elapsed = (jiffies - fc->start_time) / HZ;
282 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
283
284
285
286 pb->bio_submitted = true;
287
288
289
290
291 if (bio_data_dir(bio) == READ)
292 goto map_bio;
293
294
295
296
297 if (test_bit(DROP_WRITES, &fc->flags)) {
298 bio_endio(bio, 0);
299 return DM_MAPIO_SUBMITTED;
300 }
301
302
303
304
305 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
306 if (all_corrupt_bio_flags_match(bio, fc))
307 corrupt_bio_data(bio, fc);
308 goto map_bio;
309 }
310
311
312
313
314 return -EIO;
315 }
316
317map_bio:
318 flakey_map_bio(ti, bio);
319
320 return DM_MAPIO_REMAPPED;
321}
322
323static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
324{
325 struct flakey_c *fc = ti->private;
326 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
327
328
329
330
331
332 if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
333 (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
334 all_corrupt_bio_flags_match(bio, fc))
335 corrupt_bio_data(bio, fc);
336
337 return error;
338}
339
340static void flakey_status(struct dm_target *ti, status_type_t type,
341 unsigned status_flags, char *result, unsigned maxlen)
342{
343 unsigned sz = 0;
344 struct flakey_c *fc = ti->private;
345 unsigned drop_writes;
346
347 switch (type) {
348 case STATUSTYPE_INFO:
349 result[0] = '\0';
350 break;
351
352 case STATUSTYPE_TABLE:
353 DMEMIT("%s %llu %u %u ", fc->dev->name,
354 (unsigned long long)fc->start, fc->up_interval,
355 fc->down_interval);
356
357 drop_writes = test_bit(DROP_WRITES, &fc->flags);
358 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
359
360 if (drop_writes)
361 DMEMIT("drop_writes ");
362
363 if (fc->corrupt_bio_byte)
364 DMEMIT("corrupt_bio_byte %u %c %u %u ",
365 fc->corrupt_bio_byte,
366 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
367 fc->corrupt_bio_value, fc->corrupt_bio_flags);
368
369 break;
370 }
371}
372
373static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
374{
375 struct flakey_c *fc = ti->private;
376 struct dm_dev *dev = fc->dev;
377 int r = 0;
378
379
380
381
382 if (fc->start ||
383 ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
384 r = scsi_verify_blk_ioctl(NULL, cmd);
385
386 return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
387}
388
389static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
390 struct bio_vec *biovec, int max_size)
391{
392 struct flakey_c *fc = ti->private;
393 struct request_queue *q = bdev_get_queue(fc->dev->bdev);
394
395 if (!q->merge_bvec_fn)
396 return max_size;
397
398 bvm->bi_bdev = fc->dev->bdev;
399 bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
400
401 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
402}
403
404static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
405{
406 struct flakey_c *fc = ti->private;
407
408 return fn(ti, fc->dev, fc->start, ti->len, data);
409}
410
411static struct target_type flakey_target = {
412 .name = "flakey",
413 .version = {1, 3, 1},
414 .module = THIS_MODULE,
415 .ctr = flakey_ctr,
416 .dtr = flakey_dtr,
417 .map = flakey_map,
418 .end_io = flakey_end_io,
419 .status = flakey_status,
420 .ioctl = flakey_ioctl,
421 .merge = flakey_merge,
422 .iterate_devices = flakey_iterate_devices,
423};
424
425static int __init dm_flakey_init(void)
426{
427 int r = dm_register_target(&flakey_target);
428
429 if (r < 0)
430 DMERR("register failed %d", r);
431
432 return r;
433}
434
435static void __exit dm_flakey_exit(void)
436{
437 dm_unregister_target(&flakey_target);
438}
439
440
441module_init(dm_flakey_init);
442module_exit(dm_flakey_exit);
443
444MODULE_DESCRIPTION(DM_NAME " flakey target");
445MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
446MODULE_LICENSE("GPL");
447
