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 {
42 static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
49 static struct dm_arg _args[] = {
50 {0, 6, "Invalid number of feature args"},
51 {1, UINT_MAX, "Invalid corrupt bio byte"},
52 {0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
53 {0, UINT_MAX, "Invalid corrupt bio flags mask"},
56 /* No feature arguments supplied. */
60 r = dm_read_arg_group(_args, as, &argc, &ti->error);
65 arg_name = dm_shift_arg(as);
71 if (!strcasecmp(arg_name, "drop_writes")) {
72 if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
73 ti->error = "Feature drop_writes duplicated";
81 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
83 if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
85 ti->error = "Feature corrupt_bio_byte requires parameters";
87 r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
95 arg_name = dm_shift_arg(as);
96 if (!strcasecmp(arg_name, "w"))
97 fc->corrupt_bio_rw = WRITE;
98 else if (!strcasecmp(arg_name, "r"))
99 fc->corrupt_bio_rw = READ;
101 ti->error = "Invalid corrupt bio direction (r or w)";
107 * Value of byte (0-255) to write in place of correct one.
109 r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
115 * Only corrupt bios with these flags set.
117 r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
125 ti->error = "Unrecognised flakey feature requested";
129 if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
130 ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
138 * Construct a flakey mapping:
139 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
143 * [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
145 * Nth_byte starts from 1 for the first byte.
146 * Direction is r for READ or w for WRITE.
147 * bio_flags is ignored if 0.
149 static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
151 static struct dm_arg _args[] = {
152 {0, UINT_MAX, "Invalid up interval"},
153 {0, UINT_MAX, "Invalid down interval"},
158 unsigned long long tmpll;
159 struct dm_arg_set as;
166 ti->error = "Invalid argument count";
170 fc = kzalloc(sizeof(*fc), GFP_KERNEL);
172 ti->error = "Cannot allocate linear context";
175 fc->start_time = jiffies;
177 devname = dm_shift_arg(&as);
179 if (sscanf(dm_shift_arg(&as), "%llu", &tmpll) != 1) {
180 ti->error = "Invalid device sector";
185 r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
189 r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
193 if (!(fc->up_interval + fc->down_interval)) {
194 ti->error = "Total (up + down) interval is zero";
198 if (fc->up_interval + fc->down_interval < fc->up_interval) {
199 ti->error = "Interval overflow";
203 r = parse_features(&as, fc, ti);
207 if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
208 ti->error = "Device lookup failed";
212 ti->num_flush_requests = 1;
213 ti->num_discard_requests = 1;
222 static void flakey_dtr(struct dm_target *ti)
224 struct flakey_c *fc = ti->private;
226 dm_put_device(ti, fc->dev);
230 static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
232 struct flakey_c *fc = ti->private;
234 return fc->start + dm_target_offset(ti, bi_sector);
237 static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
239 struct flakey_c *fc = ti->private;
241 bio->bi_bdev = fc->dev->bdev;
242 if (bio_sectors(bio))
243 bio->bi_sector = flakey_map_sector(ti, bio->bi_sector);
246 static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
248 unsigned bio_bytes = bio_cur_bytes(bio);
249 char *data = bio_data(bio);
252 * Overwrite the Nth byte of the data returned.
254 if (data && bio_bytes >= fc->corrupt_bio_byte) {
255 data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
257 DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
258 "(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
259 bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
260 (bio_data_dir(bio) == WRITE) ? 'w' : 'r',
261 bio->bi_rw, (unsigned long long)bio->bi_sector, bio_bytes);
265 static int flakey_map(struct dm_target *ti, struct bio *bio,
266 union map_info *map_context)
268 struct flakey_c *fc = ti->private;
272 elapsed = (jiffies - fc->start_time) / HZ;
273 if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
275 * Flag this bio as submitted while down.
280 * Map reads as normal.
282 if (bio_data_dir(bio) == READ)
288 if (test_bit(DROP_WRITES, &fc->flags)) {
290 return DM_MAPIO_SUBMITTED;
294 * Corrupt matching writes.
296 if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
297 if (all_corrupt_bio_flags_match(bio, fc))
298 corrupt_bio_data(bio, fc);
303 * By default, error all I/O.
309 flakey_map_bio(ti, bio);
311 return DM_MAPIO_REMAPPED;
314 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
315 int error, union map_info *map_context)
317 struct flakey_c *fc = ti->private;
318 unsigned bio_submitted_while_down = map_context->ll;
321 * Corrupt successful READs while in down state.
322 * If flags were specified, only corrupt those that match.
324 if (!error && bio_submitted_while_down &&
325 (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
326 all_corrupt_bio_flags_match(bio, fc))
327 corrupt_bio_data(bio, fc);
332 static int flakey_status(struct dm_target *ti, status_type_t type,
333 char *result, unsigned int maxlen)
336 struct flakey_c *fc = ti->private;
337 unsigned drop_writes;
340 case STATUSTYPE_INFO:
344 case STATUSTYPE_TABLE:
345 DMEMIT("%s %llu %u %u ", fc->dev->name,
346 (unsigned long long)fc->start, fc->up_interval,
349 drop_writes = test_bit(DROP_WRITES, &fc->flags);
350 DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
353 DMEMIT("drop_writes ");
355 if (fc->corrupt_bio_byte)
356 DMEMIT("corrupt_bio_byte %u %c %u %u ",
357 fc->corrupt_bio_byte,
358 (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
359 fc->corrupt_bio_value, fc->corrupt_bio_flags);
366 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
368 struct flakey_c *fc = ti->private;
370 return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
373 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
374 struct bio_vec *biovec, int max_size)
376 struct flakey_c *fc = ti->private;
377 struct request_queue *q = bdev_get_queue(fc->dev->bdev);
379 if (!q->merge_bvec_fn)
382 bvm->bi_bdev = fc->dev->bdev;
383 bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
385 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
388 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
390 struct flakey_c *fc = ti->private;
392 return fn(ti, fc->dev, fc->start, ti->len, data);
395 static struct target_type flakey_target = {
397 .version = {1, 2, 0},
398 .module = THIS_MODULE,
402 .end_io = flakey_end_io,
403 .status = flakey_status,
404 .ioctl = flakey_ioctl,
405 .merge = flakey_merge,
406 .iterate_devices = flakey_iterate_devices,
409 static int __init dm_flakey_init(void)
411 int r = dm_register_target(&flakey_target);
414 DMERR("register failed %d", r);
419 static void __exit dm_flakey_exit(void)
421 dm_unregister_target(&flakey_target);
425 module_init(dm_flakey_init);
426 module_exit(dm_flakey_exit);
428 MODULE_DESCRIPTION(DM_NAME " flakey target");
429 MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
430 MODULE_LICENSE("GPL");