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);
75 if (!strcasecmp(arg_name, "drop_writes")) {
76 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
77 ti->error = "Feature drop_writes duplicated";
85 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
87 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
89 ti->error = "Feature corrupt_bio_byte requires parameters";
93 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
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;
107 ti->error = "Invalid corrupt bio direction (r or w)";
113 * Value of byte (0-255) to write in place of correct one.
115 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
121 * Only corrupt bios with these flags set.
123 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
131 ti->error = "Unrecognised flakey feature requested";
135 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";
144 * Construct a flakey mapping:
145 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
149 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
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.
155 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
157 static struct dm_arg _args[] = {
158 {0, UINT_MAX, "Invalid up interval"},
159 {0, UINT_MAX, "Invalid down interval"},
164 unsigned long long tmpll;
165 struct dm_arg_set as;
173 ti->error = "Invalid argument count";
177 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
179 ti->error = "Cannot allocate context";
182 fc->start_time = jiffies;
184 devname = dm_shift_arg(&as);
187 if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
188 ti->error = "Invalid device sector";
193 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
197 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
201 if (!(fc->up_interval + fc->down_interval)) {
202 ti->error = "Total (up + down) interval is zero";
207 if (fc->up_interval + fc->down_interval < fc->up_interval) {
208 ti->error = "Interval overflow";
213 r = parse_features(&as, fc, ti);
217 r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
219 ti->error = "Device lookup failed";
223 ti->num_flush_bios = 1;
224 ti->num_discard_bios = 1;
225 ti->per_bio_data_size = sizeof(struct per_bio_data);
234 static void flakey_dtr(struct dm_target *ti)
236 struct flakey_c *fc = ti->private;
238 dm_put_device(ti, fc->dev);
242 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
244 struct flakey_c *fc = ti->private;
246 return fc->start + dm_target_offset(ti, bi_sector);
249 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
251 struct flakey_c *fc = ti->private;
253 bio->bi_bdev = fc->dev->bdev;
254 if (bio_sectors(bio))
255 bio->bi_iter.bi_sector =
256 flakey_map_sector(ti, bio->bi_iter.bi_sector);
259 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
261 unsigned bio_bytes = bio_cur_bytes(bio);
262 char *data = bio_data(bio);
265 * Overwrite the Nth byte of the data returned.
267 if (data && bio_bytes >= fc->corrupt_bio_byte) {
268 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
270 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
271 "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
272 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
273 (bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw,
274 (unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
278 static int flakey_map(struct dm_target *ti, struct bio *bio)
280 struct flakey_c *fc = ti->private;
282 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
283 pb->bio_submitted = false;
286 elapsed = (jiffies - fc->start_time) / HZ;
287 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
289 * Flag this bio as submitted while down.
291 pb->bio_submitted = true;
294 * Error reads if neither corrupt_bio_byte or drop_writes are set.
295 * Otherwise, flakey_end_io() will decide if the reads should be modified.
297 if (bio_data_dir(bio) == READ) {
298 if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags))
306 if (test_bit(DROP_WRITES, &fc->flags)) {
308 return DM_MAPIO_SUBMITTED;
312 * Corrupt matching writes.
314 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
315 if (all_corrupt_bio_flags_match(bio, fc))
316 corrupt_bio_data(bio, fc);
321 * By default, error all I/O.
327 flakey_map_bio(ti, bio);
329 return DM_MAPIO_REMAPPED;
332 static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
334 struct flakey_c *fc = ti->private;
335 struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
337 if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
338 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
339 all_corrupt_bio_flags_match(bio, fc)) {
341 * Corrupt successful matching READs while in down state.
343 corrupt_bio_data(bio, fc);
345 } else if (!test_bit(DROP_WRITES, &fc->flags)) {
347 * Error read during the down_interval if drop_writes
357 static void flakey_status(struct dm_target *ti, status_type_t type,
358 unsigned status_flags, char *result, unsigned maxlen)
361 struct flakey_c *fc = ti->private;
362 unsigned drop_writes;
365 case STATUSTYPE_INFO:
369 case STATUSTYPE_TABLE:
370 DMEMIT("%s %llu %u %u ", fc->dev->name,
371 (unsigned long long)fc->start, fc->up_interval,
374 drop_writes = test_bit(DROP_WRITES, &fc->flags);
375 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
378 DMEMIT("drop_writes ");
380 if (fc->corrupt_bio_byte)
381 DMEMIT("corrupt_bio_byte %u %c %u %u ",
382 fc->corrupt_bio_byte,
383 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
384 fc->corrupt_bio_value, fc->corrupt_bio_flags);
390 static int flakey_prepare_ioctl(struct dm_target *ti,
391 struct block_device **bdev, fmode_t *mode)
393 struct flakey_c *fc = ti->private;
395 *bdev = fc->dev->bdev;
398 * Only pass ioctls through if the device sizes match exactly.
401 ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
406 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
408 struct flakey_c *fc = ti->private;
410 return fn(ti, fc->dev, fc->start, ti->len, data);
413 static struct target_type flakey_target = {
415 .version = {1, 3, 1},
416 .module = THIS_MODULE,
420 .end_io = flakey_end_io,
421 .status = flakey_status,
422 .prepare_ioctl = flakey_prepare_ioctl,
423 .iterate_devices = flakey_iterate_devices,
426 static int __init dm_flakey_init(void)
428 int r = dm_register_target(&flakey_target);
431 DMERR("register failed %d", r);
436 static void __exit dm_flakey_exit(void)
438 dm_unregister_target(&flakey_target);
442 module_init(dm_flakey_init);
443 module_exit(dm_flakey_exit);
445 MODULE_DESCRIPTION(DM_NAME " flakey target");
446 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
447 MODULE_LICENSE("GPL");