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_rw & (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_bio_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 bio_bytes = bio_cur_bytes(bio);
267 char *data = bio_data(bio);
270 * Overwrite the Nth byte of the data returned.
272 if (data && bio_bytes >= fc->corrupt_bio_byte) {
273 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
275 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
276 "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
277 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
278 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw,
279 (unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
283 static int flakey_map(struct dm_target *ti, struct bio *bio)
285 struct flakey_c *fc = ti->private;
287 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
288 pb->bio_submitted = false;
291 elapsed = (jiffies - fc->start_time) / HZ;
292 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
294 * Flag this bio as submitted while down.
296 pb->bio_submitted = true;
299 * Error reads if neither corrupt_bio_byte or drop_writes are set.
300 * Otherwise, flakey_end_io() will decide if the reads should be modified.
302 if (bio_data_dir(bio) == READ) {
303 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags))
311 if (test_bit(DROP_WRITES, &fc->flags)) {
313 return DM_MAPIO_SUBMITTED;
317 * Corrupt matching writes.
319 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
320 if (all_corrupt_bio_flags_match(bio, fc))
321 corrupt_bio_data(bio, fc);
326 * By default, error all I/O.
332 flakey_map_bio(ti, bio);
334 return DM_MAPIO_REMAPPED;
337 static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
339 struct flakey_c *fc = ti->private;
340 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
342 if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
343 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
344 all_corrupt_bio_flags_match(bio, fc)) {
346 * Corrupt successful matching READs while in down state.
348 corrupt_bio_data(bio, fc);
350 } else if (!test_bit(DROP_WRITES, &fc->flags)) {
352 * Error read during the down_interval if drop_writes
362 static void flakey_status(struct dm_target *ti, status_type_t type,
363 unsigned status_flags, char *result, unsigned maxlen)
366 struct flakey_c *fc = ti->private;
367 unsigned drop_writes;
370 case STATUSTYPE_INFO:
374 case STATUSTYPE_TABLE:
375 DMEMIT("%s %llu %u %u ", fc->dev->name,
376 (unsigned long long)fc->start, fc->up_interval,
379 drop_writes = test_bit(DROP_WRITES, &fc->flags);
380 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
383 DMEMIT("drop_writes ");
385 if (fc->corrupt_bio_byte)
386 DMEMIT("corrupt_bio_byte %u %c %u %u ",
387 fc->corrupt_bio_byte,
388 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
389 fc->corrupt_bio_value, fc->corrupt_bio_flags);
395 static int flakey_prepare_ioctl(struct dm_target *ti,
396 struct block_device **bdev, fmode_t *mode)
398 struct flakey_c *fc = ti->private;
400 *bdev = fc->dev->bdev;
403 * Only pass ioctls through if the device sizes match exactly.
406 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
411 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
413 struct flakey_c *fc = ti->private;
415 return fn(ti, fc->dev, fc->start, ti->len, data);
418 static struct target_type flakey_target = {
420 .version = {1, 3, 1},
421 .module = THIS_MODULE,
425 .end_io = flakey_end_io,
426 .status = flakey_status,
427 .prepare_ioctl = flakey_prepare_ioctl,
428 .iterate_devices = flakey_iterate_devices,
431 static int __init dm_flakey_init(void)
433 int r = dm_register_target(&flakey_target);
436 DMERR("register failed %d", r);
441 static void __exit dm_flakey_exit(void)
443 dm_unregister_target(&flakey_target);
447 module_init(dm_flakey_init);
448 module_exit(dm_flakey_exit);
450 MODULE_DESCRIPTION(DM_NAME " flakey target");
451 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
452 MODULE_LICENSE("GPL");