2 * Copyright (C) 2003 Sistina Software (UK) Limited.
3 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
5 * This file is released under the GPL.
8 #include <linux/device-mapper.h>
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>
16 #define DM_MSG_PREFIX "flakey"
18 #define all_corrupt_bio_flags_match(bio, fc) \
19 (((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
22 * Flakey: Used for testing only, simulates intermittent,
23 * catastrophic device failure.
27 unsigned long start_time;
30 unsigned down_interval;
32 unsigned corrupt_bio_byte;
33 unsigned corrupt_bio_rw;
34 unsigned corrupt_bio_value;
35 unsigned corrupt_bio_flags;
38 enum feature_flag_bits {
46 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
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"},
60 /* No feature arguments supplied. */
64 r = dm_read_arg_group(_args, as, &argc, &ti->error);
69 arg_name = dm_shift_arg(as);
73 ti->error = "Insufficient feature arguments";
80 if (!strcasecmp(arg_name, "drop_writes")) {
81 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
82 ti->error = "Feature drop_writes duplicated";
90 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
92 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
94 ti->error = "Feature corrupt_bio_byte requires parameters";
98 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
106 arg_name = dm_shift_arg(as);
107 if (!strcasecmp(arg_name, "w"))
108 fc->corrupt_bio_rw = WRITE;
109 else if (!strcasecmp(arg_name, "r"))
110 fc->corrupt_bio_rw = READ;
112 ti->error = "Invalid corrupt bio direction (r or w)";
118 * Value of byte (0-255) to write in place of correct one.
120 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
126 * Only corrupt bios with these flags set.
128 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
136 ti->error = "Unrecognised flakey feature requested";
140 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
141 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
149 * Construct a flakey mapping:
150 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
154 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
156 * Nth_byte starts from 1 for the first byte.
157 * Direction is r for READ or w for WRITE.
158 * bio_flags is ignored if 0.
160 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
162 static struct dm_arg _args[] = {
163 {0, UINT_MAX, "Invalid up interval"},
164 {0, UINT_MAX, "Invalid down interval"},
169 unsigned long long tmpll;
170 struct dm_arg_set as;
178 ti->error = "Invalid argument count";
182 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
184 ti->error = "Cannot allocate context";
187 fc->start_time = jiffies;
189 devname = dm_shift_arg(&as);
192 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
193 ti->error = "Invalid device sector";
198 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
202 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
206 if (!(fc->up_interval + fc->down_interval)) {
207 ti->error = "Total (up + down) interval is zero";
212 if (fc->up_interval + fc->down_interval < fc->up_interval) {
213 ti->error = "Interval overflow";
218 r = parse_features(&as, fc, ti);
222 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
224 ti->error = "Device lookup failed";
228 ti->num_flush_bios = 1;
229 ti->num_discard_bios = 1;
230 ti->per_io_data_size = sizeof(struct per_bio_data);
239 static void flakey_dtr(struct dm_target *ti)
241 struct flakey_c *fc = ti->private;
243 dm_put_device(ti, fc->dev);
247 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
249 struct flakey_c *fc = ti->private;
251 return fc->start + dm_target_offset(ti, bi_sector);
254 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
256 struct flakey_c *fc = ti->private;
258 bio->bi_bdev = fc->dev->bdev;
259 if (bio_sectors(bio))
260 bio->bi_iter.bi_sector =
261 flakey_map_sector(ti, bio->bi_iter.bi_sector);
264 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
266 unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
268 struct bvec_iter iter;
271 if (!bio_has_data(bio))
275 * Overwrite the Nth byte of the bio's data, on whichever page
278 bio_for_each_segment(bvec, bio, iter) {
279 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
280 char *segment = (page_address(bio_iter_page(bio, iter))
281 + bio_iter_offset(bio, iter));
282 segment[corrupt_bio_byte] = fc->corrupt_bio_value;
283 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
284 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
285 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
286 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
287 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
290 corrupt_bio_byte -= bio_iter_len(bio, iter);
294 static int flakey_map(struct dm_target *ti, struct bio *bio)
296 struct flakey_c *fc = ti->private;
298 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
299 pb->bio_submitted = false;
302 elapsed = (jiffies - fc->start_time) / HZ;
303 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
305 * Flag this bio as submitted while down.
307 pb->bio_submitted = true;
310 * Error reads if neither corrupt_bio_byte or drop_writes are set.
311 * Otherwise, flakey_end_io() will decide if the reads should be modified.
313 if (bio_data_dir(bio) == READ) {
314 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags))
322 if (test_bit(DROP_WRITES, &fc->flags)) {
324 return DM_MAPIO_SUBMITTED;
328 * Corrupt matching writes.
330 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
331 if (all_corrupt_bio_flags_match(bio, fc))
332 corrupt_bio_data(bio, fc);
337 * By default, error all I/O.
343 flakey_map_bio(ti, bio);
345 return DM_MAPIO_REMAPPED;
348 static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
350 struct flakey_c *fc = ti->private;
351 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
353 if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
354 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
355 all_corrupt_bio_flags_match(bio, fc)) {
357 * Corrupt successful matching READs while in down state.
359 corrupt_bio_data(bio, fc);
361 } else if (!test_bit(DROP_WRITES, &fc->flags)) {
363 * Error read during the down_interval if drop_writes
373 static void flakey_status(struct dm_target *ti, status_type_t type,
374 unsigned status_flags, char *result, unsigned maxlen)
377 struct flakey_c *fc = ti->private;
378 unsigned drop_writes;
381 case STATUSTYPE_INFO:
385 case STATUSTYPE_TABLE:
386 DMEMIT("%s %llu %u %u ", fc->dev->name,
387 (unsigned long long)fc->start, fc->up_interval,
390 drop_writes = test_bit(DROP_WRITES, &fc->flags);
391 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
394 DMEMIT("drop_writes ");
396 if (fc->corrupt_bio_byte)
397 DMEMIT("corrupt_bio_byte %u %c %u %u ",
398 fc->corrupt_bio_byte,
399 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
400 fc->corrupt_bio_value, fc->corrupt_bio_flags);
406 static int flakey_prepare_ioctl(struct dm_target *ti,
407 struct block_device **bdev, fmode_t *mode)
409 struct flakey_c *fc = ti->private;
411 *bdev = fc->dev->bdev;
414 * Only pass ioctls through if the device sizes match exactly.
417 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
422 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
424 struct flakey_c *fc = ti->private;
426 return fn(ti, fc->dev, fc->start, ti->len, data);
429 static struct target_type flakey_target = {
431 .version = {1, 3, 1},
432 .module = THIS_MODULE,
436 .end_io = flakey_end_io,
437 .status = flakey_status,
438 .prepare_ioctl = flakey_prepare_ioctl,
439 .iterate_devices = flakey_iterate_devices,
442 static int __init dm_flakey_init(void)
444 int r = dm_register_target(&flakey_target);
447 DMERR("register failed %d", r);
452 static void __exit dm_flakey_exit(void)
454 dm_unregister_target(&flakey_target);
458 module_init(dm_flakey_init);
459 module_exit(dm_flakey_exit);
461 MODULE_DESCRIPTION(DM_NAME " flakey target");
462 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
463 MODULE_LICENSE("GPL");