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 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);
76 if (!strcasecmp(arg_name, "drop_writes")) {
77 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
78 ti->error = "Feature drop_writes duplicated";
80 } else if (test_bit(ERROR_WRITES, &fc->flags)) {
81 ti->error = "Feature drop_writes conflicts with feature error_writes";
91 if (!strcasecmp(arg_name, "error_writes")) {
92 if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
93 ti->error = "Feature error_writes duplicated";
96 } else if (test_bit(DROP_WRITES, &fc->flags)) {
97 ti->error = "Feature error_writes conflicts with feature drop_writes";
105 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
107 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
109 ti->error = "Feature corrupt_bio_byte requires parameters";
113 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
121 arg_name = dm_shift_arg(as);
122 if (!strcasecmp(arg_name, "w"))
123 fc->corrupt_bio_rw = WRITE;
124 else if (!strcasecmp(arg_name, "r"))
125 fc->corrupt_bio_rw = READ;
127 ti->error = "Invalid corrupt bio direction (r or w)";
133 * Value of byte (0-255) to write in place of correct one.
135 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
141 * Only corrupt bios with these flags set.
143 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
151 ti->error = "Unrecognised flakey feature requested";
155 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
156 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
159 } else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
160 ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
168 * Construct a flakey mapping:
169 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
173 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
175 * Nth_byte starts from 1 for the first byte.
176 * Direction is r for READ or w for WRITE.
177 * bio_flags is ignored if 0.
179 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
181 static struct dm_arg _args[] = {
182 {0, UINT_MAX, "Invalid up interval"},
183 {0, UINT_MAX, "Invalid down interval"},
188 unsigned long long tmpll;
189 struct dm_arg_set as;
197 ti->error = "Invalid argument count";
201 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
203 ti->error = "Cannot allocate context";
206 fc->start_time = jiffies;
208 devname = dm_shift_arg(&as);
211 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
212 ti->error = "Invalid device sector";
217 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
221 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
225 if (!(fc->up_interval + fc->down_interval)) {
226 ti->error = "Total (up + down) interval is zero";
231 if (fc->up_interval + fc->down_interval < fc->up_interval) {
232 ti->error = "Interval overflow";
237 r = parse_features(&as, fc, ti);
241 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
243 ti->error = "Device lookup failed";
247 ti->num_flush_bios = 1;
248 ti->num_discard_bios = 1;
249 ti->per_io_data_size = sizeof(struct per_bio_data);
258 static void flakey_dtr(struct dm_target *ti)
260 struct flakey_c *fc = ti->private;
262 dm_put_device(ti, fc->dev);
266 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
268 struct flakey_c *fc = ti->private;
270 return fc->start + dm_target_offset(ti, bi_sector);
273 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
275 struct flakey_c *fc = ti->private;
277 bio->bi_bdev = fc->dev->bdev;
278 if (bio_sectors(bio))
279 bio->bi_iter.bi_sector =
280 flakey_map_sector(ti, bio->bi_iter.bi_sector);
283 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
285 unsigned bio_bytes = bio_cur_bytes(bio);
286 char *data = bio_data(bio);
289 * Overwrite the Nth byte of the data returned.
291 if (data && bio_bytes >= fc->corrupt_bio_byte) {
292 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
294 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
295 "(rw=%c bi_opf=%u bi_sector=%llu cur_bytes=%u)\n",
296 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
297 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
298 (unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
302 static int flakey_map(struct dm_target *ti, struct bio *bio)
304 struct flakey_c *fc = ti->private;
306 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
307 pb->bio_submitted = false;
310 elapsed = (jiffies - fc->start_time) / HZ;
311 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
313 * Flag this bio as submitted while down.
315 pb->bio_submitted = true;
318 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
319 * Otherwise, flakey_end_io() will decide if the reads should be modified.
321 if (bio_data_dir(bio) == READ) {
322 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
323 !test_bit(ERROR_WRITES, &fc->flags))
329 * Drop or error writes?
331 if (test_bit(DROP_WRITES, &fc->flags)) {
333 return DM_MAPIO_SUBMITTED;
335 else if (test_bit(ERROR_WRITES, &fc->flags)) {
337 return DM_MAPIO_SUBMITTED;
341 * Corrupt matching writes.
343 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
344 if (all_corrupt_bio_flags_match(bio, fc))
345 corrupt_bio_data(bio, fc);
350 * By default, error all I/O.
356 flakey_map_bio(ti, bio);
358 return DM_MAPIO_REMAPPED;
361 static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
363 struct flakey_c *fc = ti->private;
364 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
366 if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
367 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
368 all_corrupt_bio_flags_match(bio, fc)) {
370 * Corrupt successful matching READs while in down state.
372 corrupt_bio_data(bio, fc);
374 } else if (!test_bit(DROP_WRITES, &fc->flags) &&
375 !test_bit(ERROR_WRITES, &fc->flags)) {
377 * Error read during the down_interval if drop_writes
378 * and error_writes were not configured.
387 static void flakey_status(struct dm_target *ti, status_type_t type,
388 unsigned status_flags, char *result, unsigned maxlen)
391 struct flakey_c *fc = ti->private;
392 unsigned drop_writes, error_writes;
395 case STATUSTYPE_INFO:
399 case STATUSTYPE_TABLE:
400 DMEMIT("%s %llu %u %u ", fc->dev->name,
401 (unsigned long long)fc->start, fc->up_interval,
404 drop_writes = test_bit(DROP_WRITES, &fc->flags);
405 error_writes = test_bit(ERROR_WRITES, &fc->flags);
406 DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
409 DMEMIT("drop_writes ");
410 else if (error_writes)
411 DMEMIT("error_writes ");
413 if (fc->corrupt_bio_byte)
414 DMEMIT("corrupt_bio_byte %u %c %u %u ",
415 fc->corrupt_bio_byte,
416 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
417 fc->corrupt_bio_value, fc->corrupt_bio_flags);
423 static int flakey_prepare_ioctl(struct dm_target *ti,
424 struct block_device **bdev, fmode_t *mode)
426 struct flakey_c *fc = ti->private;
428 *bdev = fc->dev->bdev;
431 * Only pass ioctls through if the device sizes match exactly.
434 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
439 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
441 struct flakey_c *fc = ti->private;
443 return fn(ti, fc->dev, fc->start, ti->len, data);
446 static struct target_type flakey_target = {
448 .version = {1, 4, 0},
449 .module = THIS_MODULE,
453 .end_io = flakey_end_io,
454 .status = flakey_status,
455 .prepare_ioctl = flakey_prepare_ioctl,
456 .iterate_devices = flakey_iterate_devices,
459 static int __init dm_flakey_init(void)
461 int r = dm_register_target(&flakey_target);
464 DMERR("register failed %d", r);
469 static void __exit dm_flakey_exit(void)
471 dm_unregister_target(&flakey_target);
475 module_init(dm_flakey_init);
476 module_exit(dm_flakey_exit);
478 MODULE_DESCRIPTION(DM_NAME " flakey target");
479 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
480 MODULE_LICENSE("GPL");