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Josef Bacik3407ef52011-03-24 13:54:24 +00001/*
2 * Copyright (C) 2003 Sistina Software (UK) Limited.
Mike Snitzera3998792011-08-02 12:32:06 +01003 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
Josef Bacik3407ef52011-03-24 13:54:24 +00004 *
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
Mike Snitzera3998792011-08-02 12:32:06 +010018#define all_corrupt_bio_flags_match(bio, fc) \
19 (((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
20
Josef Bacik3407ef52011-03-24 13:54:24 +000021/*
22 * Flakey: Used for testing only, simulates intermittent,
23 * catastrophic device failure.
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;
Mike Snitzerb26f5e32011-08-02 12:32:05 +010031 unsigned long flags;
Mike Snitzera3998792011-08-02 12:32:06 +010032 unsigned corrupt_bio_byte;
33 unsigned corrupt_bio_rw;
34 unsigned corrupt_bio_value;
35 unsigned corrupt_bio_flags;
Josef Bacik3407ef52011-03-24 13:54:24 +000036};
37
Mike Snitzerb26f5e32011-08-02 12:32:05 +010038enum feature_flag_bits {
39 DROP_WRITES
40};
41
Mikulas Patockac7cfdf52012-12-21 20:23:39 +000042struct per_bio_data {
43 bool bio_submitted;
44};
45
Mike Snitzerb26f5e32011-08-02 12:32:05 +010046static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
47 struct dm_target *ti)
Mike Snitzerdfd068b2011-08-02 12:32:05 +010048{
49 int r;
50 unsigned argc;
51 const char *arg_name;
52
53 static struct dm_arg _args[] = {
Mike Snitzera3998792011-08-02 12:32:06 +010054 {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"},
Mike Snitzerdfd068b2011-08-02 12:32:05 +010058 };
59
60 /* No feature arguments supplied. */
61 if (!as->argc)
62 return 0;
63
64 r = dm_read_arg_group(_args, as, &argc, &ti->error);
65 if (r)
Mike Snitzera3998792011-08-02 12:32:06 +010066 return r;
Mike Snitzerdfd068b2011-08-02 12:32:05 +010067
Mike Snitzera3998792011-08-02 12:32:06 +010068 while (argc) {
Mike Snitzerdfd068b2011-08-02 12:32:05 +010069 arg_name = dm_shift_arg(as);
70 argc--;
71
Mike Snitzerb26f5e32011-08-02 12:32:05 +010072 /*
73 * drop_writes
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
Mike Snitzera3998792011-08-02 12:32:06 +010084 /*
85 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
86 */
87 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
Mike Snitzer68e58a22011-09-25 23:26:15 +010088 if (!argc) {
Mike Snitzera3998792011-08-02 12:32:06 +010089 ti->error = "Feature corrupt_bio_byte requires parameters";
Mike Snitzer68e58a22011-09-25 23:26:15 +010090 return -EINVAL;
91 }
Mike Snitzera3998792011-08-02 12:32:06 +010092
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 * Direction r or w?
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 * Value of byte (0-255) to write in place of correct one.
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 * Only corrupt bios with these flags set.
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
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100131 ti->error = "Unrecognised flakey feature requested";
Mike Snitzera3998792011-08-02 12:32:06 +0100132 return -EINVAL;
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100133 }
134
Mike Snitzera3998792011-08-02 12:32:06 +0100135 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;
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100141}
142
Josef Bacik3407ef52011-03-24 13:54:24 +0000143/*
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100144 * Construct a flakey mapping:
145 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100146 *
147 * Feature args:
148 * [drop_writes]
Mike Snitzera3998792011-08-02 12:32:06 +0100149 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
150 *
151 * Nth_byte starts from 1 for the first byte.
152 * Direction is r for READ or w for WRITE.
153 * bio_flags is ignored if 0.
Josef Bacik3407ef52011-03-24 13:54:24 +0000154 */
155static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
156{
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100157 static struct dm_arg _args[] = {
158 {0, UINT_MAX, "Invalid up interval"},
159 {0, UINT_MAX, "Invalid down interval"},
160 };
Josef Bacik3407ef52011-03-24 13:54:24 +0000161
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100162 int r;
163 struct flakey_c *fc;
164 unsigned long long tmpll;
165 struct dm_arg_set as;
166 const char *devname;
Mikulas Patocka31998ef2012-03-28 18:41:26 +0100167 char dummy;
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100168
169 as.argc = argc;
170 as.argv = argv;
171
172 if (argc < 4) {
173 ti->error = "Invalid argument count";
Josef Bacik3407ef52011-03-24 13:54:24 +0000174 return -EINVAL;
175 }
176
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100177 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
Josef Bacik3407ef52011-03-24 13:54:24 +0000178 if (!fc) {
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100179 ti->error = "Cannot allocate linear context";
Josef Bacik3407ef52011-03-24 13:54:24 +0000180 return -ENOMEM;
181 }
182 fc->start_time = jiffies;
183
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100184 devname = dm_shift_arg(&as);
Josef Bacik3407ef52011-03-24 13:54:24 +0000185
Mikulas Patocka31998ef2012-03-28 18:41:26 +0100186 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100187 ti->error = "Invalid device sector";
Josef Bacik3407ef52011-03-24 13:54:24 +0000188 goto bad;
189 }
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100190 fc->start = tmpll;
Josef Bacik3407ef52011-03-24 13:54:24 +0000191
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100192 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
193 if (r)
Josef Bacik3407ef52011-03-24 13:54:24 +0000194 goto bad;
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100195
196 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
197 if (r)
198 goto bad;
Josef Bacik3407ef52011-03-24 13:54:24 +0000199
200 if (!(fc->up_interval + fc->down_interval)) {
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100201 ti->error = "Total (up + down) interval is zero";
Josef Bacik3407ef52011-03-24 13:54:24 +0000202 goto bad;
203 }
204
205 if (fc->up_interval + fc->down_interval < fc->up_interval) {
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100206 ti->error = "Interval overflow";
Josef Bacik3407ef52011-03-24 13:54:24 +0000207 goto bad;
208 }
209
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100210 r = parse_features(&as, fc, ti);
Mike Snitzerdfd068b2011-08-02 12:32:05 +0100211 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";
Josef Bacik3407ef52011-03-24 13:54:24 +0000216 goto bad;
217 }
218
Alasdair G Kergon55a62ee2013-03-01 22:45:47 +0000219 ti->num_flush_bios = 1;
220 ti->num_discard_bios = 1;
Mikulas Patockac7cfdf52012-12-21 20:23:39 +0000221 ti->per_bio_data_size = sizeof(struct per_bio_data);
Josef Bacik3407ef52011-03-24 13:54:24 +0000222 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
Mike Snitzer30e41712011-08-02 12:32:05 +0100242 return fc->start + dm_target_offset(ti, bi_sector);
Josef Bacik3407ef52011-03-24 13:54:24 +0000243}
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
Mike Snitzera3998792011-08-02 12:32:06 +0100254static 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 * Overwrite the Nth byte of the data returned.
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
Mikulas Patocka7de3ee52012-12-21 20:23:41 +0000273static int flakey_map(struct dm_target *ti, struct bio *bio)
Josef Bacik3407ef52011-03-24 13:54:24 +0000274{
275 struct flakey_c *fc = ti->private;
276 unsigned elapsed;
Mikulas Patockac7cfdf52012-12-21 20:23:39 +0000277 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
278 pb->bio_submitted = false;
Josef Bacik3407ef52011-03-24 13:54:24 +0000279
280 /* Are we alive ? */
281 elapsed = (jiffies - fc->start_time) / HZ;
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100282 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
Mike Snitzera3998792011-08-02 12:32:06 +0100283 /*
284 * Flag this bio as submitted while down.
285 */
Mikulas Patockac7cfdf52012-12-21 20:23:39 +0000286 pb->bio_submitted = true;
Josef Bacik3407ef52011-03-24 13:54:24 +0000287
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100288 /*
Mike Snitzera3998792011-08-02 12:32:06 +0100289 * Map reads as normal.
290 */
291 if (bio_data_dir(bio) == READ)
292 goto map_bio;
293
294 /*
295 * Drop writes?
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100296 */
297 if (test_bit(DROP_WRITES, &fc->flags)) {
Mike Snitzera3998792011-08-02 12:32:06 +0100298 bio_endio(bio, 0);
299 return DM_MAPIO_SUBMITTED;
300 }
301
302 /*
303 * Corrupt matching writes.
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);
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100308 goto map_bio;
309 }
310
311 /*
Mike Snitzera3998792011-08-02 12:32:06 +0100312 * By default, error all I/O.
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100313 */
314 return -EIO;
315 }
316
317map_bio:
Josef Bacik3407ef52011-03-24 13:54:24 +0000318 flakey_map_bio(ti, bio);
319
320 return DM_MAPIO_REMAPPED;
321}
322
Mikulas Patocka7de3ee52012-12-21 20:23:41 +0000323static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
Mike Snitzera3998792011-08-02 12:32:06 +0100324{
325 struct flakey_c *fc = ti->private;
Mikulas Patockac7cfdf52012-12-21 20:23:39 +0000326 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
Mike Snitzera3998792011-08-02 12:32:06 +0100327
328 /*
329 * Corrupt successful READs while in down state.
330 * If flags were specified, only corrupt those that match.
331 */
Mikulas Patockac7cfdf52012-12-21 20:23:39 +0000332 if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
Mike Snitzera3998792011-08-02 12:32:06 +0100333 (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
Mikulas Patockafd7c0922013-03-01 22:45:44 +0000340static void flakey_status(struct dm_target *ti, status_type_t type,
341 unsigned status_flags, char *result, unsigned maxlen)
Josef Bacik3407ef52011-03-24 13:54:24 +0000342{
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100343 unsigned sz = 0;
Josef Bacik3407ef52011-03-24 13:54:24 +0000344 struct flakey_c *fc = ti->private;
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100345 unsigned drop_writes;
Josef Bacik3407ef52011-03-24 13:54:24 +0000346
347 switch (type) {
348 case STATUSTYPE_INFO:
349 result[0] = '\0';
350 break;
351
352 case STATUSTYPE_TABLE:
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100353 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);
Mike Snitzera3998792011-08-02 12:32:06 +0100358 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
359
Mike Snitzerb26f5e32011-08-02 12:32:05 +0100360 if (drop_writes)
361 DMEMIT("drop_writes ");
Mike Snitzera3998792011-08-02 12:32:06 +0100362
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
Josef Bacik3407ef52011-03-24 13:54:24 +0000369 break;
370 }
Josef Bacik3407ef52011-03-24 13:54:24 +0000371}
372
373static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
374{
375 struct flakey_c *fc = ti->private;
Paolo Bonziniec8013b2012-01-12 16:01:29 +0100376 struct dm_dev *dev = fc->dev;
377 int r = 0;
Josef Bacik3407ef52011-03-24 13:54:24 +0000378
Paolo Bonziniec8013b2012-01-12 16:01:29 +0100379 /*
380 * Only pass ioctls through if the device sizes match exactly.
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);
Josef Bacik3407ef52011-03-24 13:54:24 +0000387}
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",
Mikulas Patockafd7c0922013-03-01 22:45:44 +0000413 .version = {1, 3, 1},
Josef Bacik3407ef52011-03-24 13:54:24 +0000414 .module = THIS_MODULE,
415 .ctr = flakey_ctr,
416 .dtr = flakey_dtr,
417 .map = flakey_map,
Mike Snitzera3998792011-08-02 12:32:06 +0100418 .end_io = flakey_end_io,
Josef Bacik3407ef52011-03-24 13:54:24 +0000419 .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/* Module hooks */
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");