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 {
47 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
54 static const struct dm_arg _args[] = {
55 {0, 6, "Invalid number of feature args"},
56 {1, UINT_MAX, "Invalid corrupt bio byte"},
57 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
58 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
61 /* No feature arguments supplied. */
65 r = dm_read_arg_group(_args, as, &argc, &ti->error);
70 arg_name = dm_shift_arg(as);
74 ti->error = "Insufficient feature arguments";
81 if (!strcasecmp(arg_name, "drop_writes")) {
82 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
83 ti->error = "Feature drop_writes duplicated";
85 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
86 ti->error = "Feature drop_writes conflicts with feature error_writes";
96 if (!strcasecmp(arg_name, "error_writes")) {
97 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
98 ti->error = "Feature error_writes duplicated";
101 } else if (test_bit(DROP_WRITES, &fc->flags)) {
102 ti->error = "Feature error_writes conflicts with feature drop_writes";
110 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
112 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
114 ti->error = "Feature corrupt_bio_byte requires parameters";
118 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
126 arg_name = dm_shift_arg(as);
127 if (arg_name && !strcasecmp(arg_name, "w"))
128 fc->corrupt_bio_rw = WRITE;
129 else if (arg_name && !strcasecmp(arg_name, "r"))
130 fc->corrupt_bio_rw = READ;
132 ti->error = "Invalid corrupt bio direction (r or w)";
138 * Value of byte (0-255) to write in place of correct one.
140 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
146 * Only corrupt bios with these flags set.
148 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
156 ti->error = "Unrecognised flakey feature requested";
160 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
161 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
164 } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
165 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
173 * Construct a flakey mapping:
174 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
178 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
180 * Nth_byte starts from 1 for the first byte.
181 * Direction is r for READ or w for WRITE.
182 * bio_flags is ignored if 0.
184 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
186 static const struct dm_arg _args[] = {
187 {0, UINT_MAX, "Invalid up interval"},
188 {0, UINT_MAX, "Invalid down interval"},
193 unsigned long long tmpll;
194 struct dm_arg_set as;
202 ti->error = "Invalid argument count";
206 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
208 ti->error = "Cannot allocate context";
211 fc->start_time = jiffies;
213 devname = dm_shift_arg(&as);
216 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
217 ti->error = "Invalid device sector";
222 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
226 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
230 if (!(fc->up_interval + fc->down_interval)) {
231 ti->error = "Total (up + down) interval is zero";
236 if (fc->up_interval + fc->down_interval < fc->up_interval) {
237 ti->error = "Interval overflow";
242 r = parse_features(&as, fc, ti);
246 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
248 ti->error = "Device lookup failed";
252 ti->num_flush_bios = 1;
253 ti->num_discard_bios = 1;
254 ti->per_io_data_size = sizeof(struct per_bio_data);
263 static void flakey_dtr(struct dm_target *ti)
265 struct flakey_c *fc = ti->private;
267 dm_put_device(ti, fc->dev);
271 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
273 struct flakey_c *fc = ti->private;
275 return fc->start + dm_target_offset(ti, bi_sector);
278 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
280 struct flakey_c *fc = ti->private;
282 bio_set_dev(bio, fc->dev->bdev);
283 if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)
284 bio->bi_iter.bi_sector =
285 flakey_map_sector(ti, bio->bi_iter.bi_sector);
288 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
290 unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
292 struct bvec_iter iter;
295 if (!bio_has_data(bio))
299 * Overwrite the Nth byte of the bio's data, on whichever page
302 bio_for_each_segment(bvec, bio, iter) {
303 if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
305 struct page *page = bio_iter_page(bio, iter);
306 if (unlikely(page == ZERO_PAGE(0)))
308 segment = (page_address(page) + bio_iter_offset(bio, iter));
309 segment[corrupt_bio_byte] = fc->corrupt_bio_value;
310 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
311 "(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
312 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
313 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
314 (unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
317 corrupt_bio_byte -= bio_iter_len(bio, iter);
321 static int flakey_map(struct dm_target *ti, struct bio *bio)
323 struct flakey_c *fc = ti->private;
325 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
326 pb->bio_submitted = false;
328 /* Do not fail reset zone */
329 if (bio_op(bio) == REQ_OP_ZONE_RESET)
332 /* We need to remap reported zones, so remember the BIO iter */
333 if (bio_op(bio) == REQ_OP_ZONE_REPORT)
337 elapsed = (jiffies - fc->start_time) / HZ;
338 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
340 * Flag this bio as submitted while down.
342 pb->bio_submitted = true;
345 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
346 * Otherwise, flakey_end_io() will decide if the reads should be modified.
348 if (bio_data_dir(bio) == READ) {
349 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
350 !test_bit(ERROR_WRITES, &fc->flags))
351 return DM_MAPIO_KILL;
356 * Drop or error writes?
358 if (test_bit(DROP_WRITES, &fc->flags)) {
360 return DM_MAPIO_SUBMITTED;
362 else if (test_bit(ERROR_WRITES, &fc->flags)) {
364 return DM_MAPIO_SUBMITTED;
368 * Corrupt matching writes.
370 if (fc->corrupt_bio_byte) {
371 if (fc->corrupt_bio_rw == WRITE) {
372 if (all_corrupt_bio_flags_match(bio, fc))
373 corrupt_bio_data(bio, fc);
379 * By default, error all I/O.
381 return DM_MAPIO_KILL;
385 flakey_map_bio(ti, bio);
387 return DM_MAPIO_REMAPPED;
390 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
393 struct flakey_c *fc = ti->private;
394 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
396 if (bio_op(bio) == REQ_OP_ZONE_RESET)
397 return DM_ENDIO_DONE;
399 if (bio_op(bio) == REQ_OP_ZONE_REPORT) {
400 dm_remap_zone_report(ti, bio, fc->start);
401 return DM_ENDIO_DONE;
404 if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
405 if (fc->corrupt_bio_byte) {
406 if ((fc->corrupt_bio_rw == READ) &&
407 all_corrupt_bio_flags_match(bio, fc)) {
409 * Corrupt successful matching READs while in down state.
411 corrupt_bio_data(bio, fc);
413 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
414 !test_bit(ERROR_WRITES, &fc->flags)) {
416 * Error read during the down_interval if drop_writes
417 * and error_writes were not configured.
419 *error = BLK_STS_IOERR;
423 return DM_ENDIO_DONE;
426 static void flakey_status(struct dm_target *ti, status_type_t type,
427 unsigned status_flags, char *result, unsigned maxlen)
430 struct flakey_c *fc = ti->private;
431 unsigned drop_writes, error_writes;
434 case STATUSTYPE_INFO:
438 case STATUSTYPE_TABLE:
439 DMEMIT("%s %llu %u %u ", fc->dev->name,
440 (unsigned long long)fc->start, fc->up_interval,
443 drop_writes = test_bit(DROP_WRITES, &fc->flags);
444 error_writes = test_bit(ERROR_WRITES, &fc->flags);
445 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
448 DMEMIT("drop_writes ");
449 else if (error_writes)
450 DMEMIT("error_writes ");
452 if (fc->corrupt_bio_byte)
453 DMEMIT("corrupt_bio_byte %u %c %u %u ",
454 fc->corrupt_bio_byte,
455 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
456 fc->corrupt_bio_value, fc->corrupt_bio_flags);
462 static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
464 struct flakey_c *fc = ti->private;
466 *bdev = fc->dev->bdev;
469 * Only pass ioctls through if the device sizes match exactly.
472 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
477 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
479 struct flakey_c *fc = ti->private;
481 return fn(ti, fc->dev, fc->start, ti->len, data);
484 static struct target_type flakey_target = {
486 .version = {1, 5, 0},
487 #ifdef CONFIG_BLK_DEV_ZONED
488 .features = DM_TARGET_ZONED_HM,
490 .module = THIS_MODULE,
494 .end_io = flakey_end_io,
495 .status = flakey_status,
496 .prepare_ioctl = flakey_prepare_ioctl,
497 .iterate_devices = flakey_iterate_devices,
500 static int __init dm_flakey_init(void)
502 int r = dm_register_target(&flakey_target);
505 DMERR("register failed %d", r);
510 static void __exit dm_flakey_exit(void)
512 dm_unregister_target(&flakey_target);
516 module_init(dm_flakey_init);
517 module_exit(dm_flakey_exit);
519 MODULE_DESCRIPTION(DM_NAME " flakey target");
520 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
521 MODULE_LICENSE("GPL");