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[platform/adaptation/renesas_rcar/renesas_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         char dummy;
164
165         as.argc = argc;
166         as.argv = argv;
167
168         if (argc < 4) {
169                 ti->error = "Invalid argument count";
170                 return -EINVAL;
171         }
172
173         fc = kzalloc(sizeof(*fc), GFP_KERNEL);
174         if (!fc) {
175                 ti->error = "Cannot allocate linear context";
176                 return -ENOMEM;
177         }
178         fc->start_time = jiffies;
179
180         devname = dm_shift_arg(&as);
181
182         if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
183                 ti->error = "Invalid device sector";
184                 goto bad;
185         }
186         fc->start = tmpll;
187
188         r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
189         if (r)
190                 goto bad;
191
192         r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
193         if (r)
194                 goto bad;
195
196         if (!(fc->up_interval + fc->down_interval)) {
197                 ti->error = "Total (up + down) interval is zero";
198                 goto bad;
199         }
200
201         if (fc->up_interval + fc->down_interval < fc->up_interval) {
202                 ti->error = "Interval overflow";
203                 goto bad;
204         }
205
206         r = parse_features(&as, fc, ti);
207         if (r)
208                 goto bad;
209
210         if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
211                 ti->error = "Device lookup failed";
212                 goto bad;
213         }
214
215         ti->num_flush_requests = 1;
216         ti->num_discard_requests = 1;
217         ti->private = fc;
218         return 0;
219
220 bad:
221         kfree(fc);
222         return -EINVAL;
223 }
224
225 static void flakey_dtr(struct dm_target *ti)
226 {
227         struct flakey_c *fc = ti->private;
228
229         dm_put_device(ti, fc->dev);
230         kfree(fc);
231 }
232
233 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
234 {
235         struct flakey_c *fc = ti->private;
236
237         return fc->start + dm_target_offset(ti, bi_sector);
238 }
239
240 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
241 {
242         struct flakey_c *fc = ti->private;
243
244         bio->bi_bdev = fc->dev->bdev;
245         if (bio_sectors(bio))
246                 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
247 }
248
249 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
250 {
251         unsigned bio_bytes = bio_cur_bytes(bio);
252         char *data = bio_data(bio);
253
254         /*
255          * Overwrite the Nth byte of the data returned.
256          */
257         if (data && bio_bytes >= fc->corrupt_bio_byte) {
258                 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
259
260                 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
261                         "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
262                         bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
263                         (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
264                         bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
265         }
266 }
267
268 static int flakey_map(struct dm_target *ti, struct bio *bio,
269                       union map_info *map_context)
270 {
271         struct flakey_c *fc = ti->private;
272         unsigned elapsed;
273
274         /* Are we alive ? */
275         elapsed = (jiffies - fc->start_time) / HZ;
276         if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
277                 /*
278                  * Flag this bio as submitted while down.
279                  */
280                 map_context->ll = 1;
281
282                 /*
283                  * Map reads as normal.
284                  */
285                 if (bio_data_dir(bio) == READ)
286                         goto map_bio;
287
288                 /*
289                  * Drop writes?
290                  */
291                 if (test_bit(DROP_WRITES, &fc->flags)) {
292                         bio_endio(bio, 0);
293                         return DM_MAPIO_SUBMITTED;
294                 }
295
296                 /*
297                  * Corrupt matching writes.
298                  */
299                 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
300                         if (all_corrupt_bio_flags_match(bio, fc))
301                                 corrupt_bio_data(bio, fc);
302                         goto map_bio;
303                 }
304
305                 /*
306                  * By default, error all I/O.
307                  */
308                 return -EIO;
309         }
310
311 map_bio:
312         flakey_map_bio(ti, bio);
313
314         return DM_MAPIO_REMAPPED;
315 }
316
317 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
318                          int error, union map_info *map_context)
319 {
320         struct flakey_c *fc = ti->private;
321         unsigned bio_submitted_while_down = map_context->ll;
322
323         /*
324          * Corrupt successful READs while in down state.
325          * If flags were specified, only corrupt those that match.
326          */
327         if (fc->corrupt_bio_byte && !error && bio_submitted_while_down &&
328             (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
329             all_corrupt_bio_flags_match(bio, fc))
330                 corrupt_bio_data(bio, fc);
331
332         return error;
333 }
334
335 static int flakey_status(struct dm_target *ti, status_type_t type,
336                          unsigned status_flags, char *result, unsigned maxlen)
337 {
338         unsigned sz = 0;
339         struct flakey_c *fc = ti->private;
340         unsigned drop_writes;
341
342         switch (type) {
343         case STATUSTYPE_INFO:
344                 result[0] = '\0';
345                 break;
346
347         case STATUSTYPE_TABLE:
348                 DMEMIT("%s %llu %u %u ", fc->dev->name,
349                        (unsigned long long)fc->start, fc->up_interval,
350                        fc->down_interval);
351
352                 drop_writes = test_bit(DROP_WRITES, &fc->flags);
353                 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
354
355                 if (drop_writes)
356                         DMEMIT("drop_writes ");
357
358                 if (fc->corrupt_bio_byte)
359                         DMEMIT("corrupt_bio_byte %u %c %u %u ",
360                                fc->corrupt_bio_byte,
361                                (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
362                                fc->corrupt_bio_value, fc->corrupt_bio_flags);
363
364                 break;
365         }
366         return 0;
367 }
368
369 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
370 {
371         struct flakey_c *fc = ti->private;
372         struct dm_dev *dev = fc->dev;
373         int r = 0;
374
375         /*
376          * Only pass ioctls through if the device sizes match exactly.
377          */
378         if (fc->start ||
379             ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
380                 r = scsi_verify_blk_ioctl(NULL, cmd);
381
382         return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
383 }
384
385 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
386                         struct bio_vec *biovec, int max_size)
387 {
388         struct flakey_c *fc = ti->private;
389         struct request_queue *q = bdev_get_queue(fc->dev->bdev);
390
391         if (!q->merge_bvec_fn)
392                 return max_size;
393
394         bvm->bi_bdev = fc->dev->bdev;
395         bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
396
397         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
398 }
399
400 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
401 {
402         struct flakey_c *fc = ti->private;
403
404         return fn(ti, fc->dev, fc->start, ti->len, data);
405 }
406
407 static struct target_type flakey_target = {
408         .name   = "flakey",
409         .version = {1, 2, 0},
410         .module = THIS_MODULE,
411         .ctr    = flakey_ctr,
412         .dtr    = flakey_dtr,
413         .map    = flakey_map,
414         .end_io = flakey_end_io,
415         .status = flakey_status,
416         .ioctl  = flakey_ioctl,
417         .merge  = flakey_merge,
418         .iterate_devices = flakey_iterate_devices,
419 };
420
421 static int __init dm_flakey_init(void)
422 {
423         int r = dm_register_target(&flakey_target);
424
425         if (r < 0)
426                 DMERR("register failed %d", r);
427
428         return r;
429 }
430
431 static void __exit dm_flakey_exit(void)
432 {
433         dm_unregister_target(&flakey_target);
434 }
435
436 /* Module hooks */
437 module_init(dm_flakey_init);
438 module_exit(dm_flakey_exit);
439
440 MODULE_DESCRIPTION(DM_NAME " flakey target");
441 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
442 MODULE_LICENSE("GPL");