746b5e8bcacd7a6e516d7ad99358c1460bfa68d6
[pandora-kernel.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_rw & (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 };
41
42 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
43                           struct dm_target *ti)
44 {
45         int r;
46         unsigned argc;
47         const char *arg_name;
48
49         static struct dm_arg _args[] = {
50                 {0, 6, "Invalid number of feature args"},
51                 {1, UINT_MAX, "Invalid corrupt bio byte"},
52                 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
53                 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
54         };
55
56         /* No feature arguments supplied. */
57         if (!as->argc)
58                 return 0;
59
60         r = dm_read_arg_group(_args, as, &argc, &ti->error);
61         if (r)
62                 return r;
63
64         while (argc) {
65                 arg_name = dm_shift_arg(as);
66                 argc--;
67
68                 /*
69                  * drop_writes
70                  */
71                 if (!strcasecmp(arg_name, "drop_writes")) {
72                         if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
73                                 ti->error = "Feature drop_writes duplicated";
74                                 return -EINVAL;
75                         }
76
77                         continue;
78                 }
79
80                 /*
81                  * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
82                  */
83                 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
84                         if (!argc) {
85                                 ti->error = "Feature corrupt_bio_byte requires parameters";
86                                 return -EINVAL;
87                         }
88
89                         r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
90                         if (r)
91                                 return r;
92                         argc--;
93
94                         /*
95                          * Direction r or w?
96                          */
97                         arg_name = dm_shift_arg(as);
98                         if (!strcasecmp(arg_name, "w"))
99                                 fc->corrupt_bio_rw = WRITE;
100                         else if (!strcasecmp(arg_name, "r"))
101                                 fc->corrupt_bio_rw = READ;
102                         else {
103                                 ti->error = "Invalid corrupt bio direction (r or w)";
104                                 return -EINVAL;
105                         }
106                         argc--;
107
108                         /*
109                          * Value of byte (0-255) to write in place of correct one.
110                          */
111                         r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
112                         if (r)
113                                 return r;
114                         argc--;
115
116                         /*
117                          * Only corrupt bios with these flags set.
118                          */
119                         r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
120                         if (r)
121                                 return r;
122                         argc--;
123
124                         continue;
125                 }
126
127                 ti->error = "Unrecognised flakey feature requested";
128                 return -EINVAL;
129         }
130
131         if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
132                 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
133                 return -EINVAL;
134         }
135
136         return 0;
137 }
138
139 /*
140  * Construct a flakey mapping:
141  * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
142  *
143  *   Feature args:
144  *     [drop_writes]
145  *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
146  *
147  *   Nth_byte starts from 1 for the first byte.
148  *   Direction is r for READ or w for WRITE.
149  *   bio_flags is ignored if 0.
150  */
151 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
152 {
153         static struct dm_arg _args[] = {
154                 {0, UINT_MAX, "Invalid up interval"},
155                 {0, UINT_MAX, "Invalid down interval"},
156         };
157
158         int r;
159         struct flakey_c *fc;
160         unsigned long long tmpll;
161         struct dm_arg_set as;
162         const char *devname;
163
164         as.argc = argc;
165         as.argv = argv;
166
167         if (argc < 4) {
168                 ti->error = "Invalid argument count";
169                 return -EINVAL;
170         }
171
172         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
173         if (!fc) {
174                 ti->error = "Cannot allocate linear context";
175                 return -ENOMEM;
176         }
177         fc->start_time = jiffies;
178
179         devname = dm_shift_arg(&as);
180
181         if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) {
182                 ti->error = "Invalid device sector";
183                 goto bad;
184         }
185         fc->start = tmpll;
186
187         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
188         if (r)
189                 goto bad;
190
191         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
192         if (r)
193                 goto bad;
194
195         if (!(fc->up_interval + fc->down_interval)) {
196                 ti->error = "Total (up + down) interval is zero";
197                 goto bad;
198         }
199
200         if (fc->up_interval + fc->down_interval < fc->up_interval) {
201                 ti->error = "Interval overflow";
202                 goto bad;
203         }
204
205         r = parse_features(&as, fc, ti);
206         if (r)
207                 goto bad;
208
209         if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
210                 ti->error = "Device lookup failed";
211                 goto bad;
212         }
213
214         ti->num_flush_requests = 1;
215         ti->num_discard_requests = 1;
216         ti->private = fc;
217         return 0;
218
219 bad:
220         kfree(fc);
221         return -EINVAL;
222 }
223
224 static void flakey_dtr(struct dm_target *ti)
225 {
226         struct flakey_c *fc = ti->private;
227
228         dm_put_device(ti, fc->dev);
229         kfree(fc);
230 }
231
232 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
233 {
234         struct flakey_c *fc = ti->private;
235
236         return fc->start + dm_target_offset(ti, bi_sector);
237 }
238
239 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
240 {
241         struct flakey_c *fc = ti->private;
242
243         bio->bi_bdev = fc->dev->bdev;
244         if (bio_sectors(bio))
245                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
246 }
247
248 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
249 {
250         unsigned bio_bytes = bio_cur_bytes(bio);
251         char *data = bio_data(bio);
252
253         /*
254          * Overwrite the Nth byte of the data returned.
255          */
256         if (data && bio_bytes >= fc->corrupt_bio_byte) {
257                 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
258
259                 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
260                         "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
261                         bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
262                         (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
263                         bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
264         }
265 }
266
267 static int flakey_map(struct dm_target *ti, struct bio *bio,
268                       union map_info *map_context)
269 {
270         struct flakey_c *fc = ti->private;
271         unsigned elapsed;
272
273         /* Are we alive ? */
274         elapsed = (jiffies - fc->start_time) / HZ;
275         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
276                 /*
277                  * Flag this bio as submitted while down.
278                  */
279                 map_context->ll = 1;
280
281                 /*
282                  * Map reads as normal.
283                  */
284                 if (bio_data_dir(bio) == READ)
285                         goto map_bio;
286
287                 /*
288                  * Drop writes?
289                  */
290                 if (test_bit(DROP_WRITES, &fc->flags)) {
291                         bio_endio(bio, 0);
292                         return DM_MAPIO_SUBMITTED;
293                 }
294
295                 /*
296                  * Corrupt matching writes.
297                  */
298                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
299                         if (all_corrupt_bio_flags_match(bio, fc))
300                                 corrupt_bio_data(bio, fc);
301                         goto map_bio;
302                 }
303
304                 /*
305                  * By default, error all I/O.
306                  */
307                 return -EIO;
308         }
309
310 map_bio:
311         flakey_map_bio(ti, bio);
312
313         return DM_MAPIO_REMAPPED;
314 }
315
316 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
317                          int error, union map_info *map_context)
318 {
319         struct flakey_c *fc = ti->private;
320         unsigned bio_submitted_while_down = map_context->ll;
321
322         /*
323          * Corrupt successful READs while in down state.
324          * If flags were specified, only corrupt those that match.
325          */
326         if (fc->corrupt_bio_byte && !error && bio_submitted_while_down &&
327             (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
328             all_corrupt_bio_flags_match(bio, fc))
329                 corrupt_bio_data(bio, fc);
330
331         return error;
332 }
333
334 static void flakey_status(struct dm_target *ti, status_type_t type,
335                           char *result, unsigned maxlen)
336 {
337         unsigned sz = 0;
338         struct flakey_c *fc = ti->private;
339         unsigned drop_writes;
340
341         switch (type) {
342         case STATUSTYPE_INFO:
343                 result[0] = '\0';
344                 break;
345
346         case STATUSTYPE_TABLE:
347                 DMEMIT("%s %llu %u %u ", fc->dev->name,
348                        (unsigned long long)fc->start, fc->up_interval,
349                        fc->down_interval);
350
351                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
352                 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
353
354                 if (drop_writes)
355                         DMEMIT("drop_writes ");
356
357                 if (fc->corrupt_bio_byte)
358                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
359                                fc->corrupt_bio_byte,
360                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
361                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
362
363                 break;
364         }
365 }
366
367 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
368 {
369         struct flakey_c *fc = ti->private;
370         struct dm_dev *dev = fc->dev;
371         int r = 0;
372
373         /*
374          * Only pass ioctls through if the device sizes match exactly.
375          */
376         if (fc->start ||
377             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
378                 r = scsi_verify_blk_ioctl(NULL, cmd);
379
380         return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
381 }
382
383 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
384                         struct bio_vec *biovec, int max_size)
385 {
386         struct flakey_c *fc = ti->private;
387         struct request_queue *q = bdev_get_queue(fc->dev->bdev);
388
389         if (!q->merge_bvec_fn)
390                 return max_size;
391
392         bvm->bi_bdev = fc->dev->bdev;
393         bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
394
395         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
396 }
397
398 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
399 {
400         struct flakey_c *fc = ti->private;
401
402         return fn(ti, fc->dev, fc->start, ti->len, data);
403 }
404
405 static struct target_type flakey_target = {
406         .name   = "flakey",
407         .version = {1, 2, 1},
408         .module = THIS_MODULE,
409         .ctr    = flakey_ctr,
410         .dtr    = flakey_dtr,
411         .map    = flakey_map,
412         .end_io = flakey_end_io,
413         .status = flakey_status,
414         .ioctl  = flakey_ioctl,
415         .merge  = flakey_merge,
416         .iterate_devices = flakey_iterate_devices,
417 };
418
419 static int __init dm_flakey_init(void)
420 {
421         int r = dm_register_target(&flakey_target);
422
423         if (r < 0)
424                 DMERR("register failed %d", r);
425
426         return r;
427 }
428
429 static void __exit dm_flakey_exit(void)
430 {
431         dm_unregister_target(&flakey_target);
432 }
433
434 /* Module hooks */
435 module_init(dm_flakey_init);
436 module_exit(dm_flakey_exit);
437
438 MODULE_DESCRIPTION(DM_NAME " flakey target");
439 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
440 MODULE_LICENSE("GPL");