/drivers/md/dm-flakey.c

  1/*
  2 * Copyright (C) 2003 Sistina Software (UK) Limited.
  3 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
  4 *
  5 * This file is released under the GPL.
  6 */
  7
  8#include <linux/device-mapper.h>
  9
 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>
 15
 16#define DM_MSG_PREFIX "flakey"
 17
 18#define all_corrupt_bio_flags_match(bio, fc)	\
 19	(((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
 20
 21/*
 22 * Flakey: Used for testing only, simulates intermittent,
 23 * catastrophic device failure.
 24 */
 25struct flakey_c {
 26	struct dm_dev *dev;
 27	unsigned long start_time;
 28	sector_t start;
 29	unsigned up_interval;
 30	unsigned down_interval;
 31	unsigned long flags;
 32	unsigned corrupt_bio_byte;
 33	unsigned corrupt_bio_rw;
 34	unsigned corrupt_bio_value;
 35	unsigned corrupt_bio_flags;
 36};
 37
 38enum feature_flag_bits {
 39	DROP_WRITES,
 40	ERROR_WRITES
 41};
 42
 43struct per_bio_data {
 44	bool bio_submitted;
 45};
 46
 47static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
 48			  struct dm_target *ti)
 49{
 50	int r;
 51	unsigned argc;
 52	const char *arg_name;
 53
 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"},
 59	};
 60
 61	/* No feature arguments supplied. */
 62	if (!as->argc)
 63		return 0;
 64
 65	r = dm_read_arg_group(_args, as, &argc, &ti->error);
 66	if (r)
 67		return r;
 68
 69	while (argc) {
 70		arg_name = dm_shift_arg(as);
 71		argc--;
 72
 73		if (!arg_name) {
 74			ti->error = "Insufficient feature arguments";
 75			return -EINVAL;
 76		}
 77
 78		/*
 79		 * drop_writes
 80		 */
 81		if (!strcasecmp(arg_name, "drop_writes")) {
 82			if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
 83				ti->error = "Feature drop_writes duplicated";
 84				return -EINVAL;
 85			} else if (test_bit(ERROR_WRITES, &fc->flags)) {
 86				ti->error = "Feature drop_writes conflicts with feature error_writes";
 87				return -EINVAL;
 88			}
 89
 90			continue;
 91		}
 92
 93		/*
 94		 * error_writes
 95		 */
 96		if (!strcasecmp(arg_name, "error_writes")) {
 97			if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
 98				ti->error = "Feature error_writes duplicated";
 99				return -EINVAL;
100
101			} else if (test_bit(DROP_WRITES, &fc->flags)) {
102				ti->error = "Feature error_writes conflicts with feature drop_writes";
103				return -EINVAL;
104			}
105
106			continue;
107		}
108
109		/*
110		 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
111		 */
112		if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
113			if (!argc) {
114				ti->error = "Feature corrupt_bio_byte requires parameters";
115				return -EINVAL;
116			}
117
118			r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
119			if (r)
120				return r;
121			argc--;
122
123			/*
124			 * Direction r or w?
125			 */
126			arg_name = dm_shift_arg(as);
127			if (!strcasecmp(arg_name, "w"))
128				fc->corrupt_bio_rw = WRITE;
129			else if (!strcasecmp(arg_name, "r"))
130				fc->corrupt_bio_rw = READ;
131			else {
132				ti->error = "Invalid corrupt bio direction (r or w)";
133				return -EINVAL;
134			}
135			argc--;
136
137			/*
138			 * Value of byte (0-255) to write in place of correct one.
139			 */
140			r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
141			if (r)
142				return r;
143			argc--;
144
145			/*
146			 * Only corrupt bios with these flags set.
147			 */
148			r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
149			if (r)
150				return r;
151			argc--;
152
153			continue;
154		}
155
156		ti->error = "Unrecognised flakey feature requested";
157		return -EINVAL;
158	}
159
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";
162		return -EINVAL;
163
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";
166		return -EINVAL;
167	}
168
169	return 0;
170}
171
172/*
173 * Construct a flakey mapping:
174 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
175 *
176 *   Feature args:
177 *     [drop_writes]
178 *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
179 *
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.
183 */
184static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
185{
186	static const struct dm_arg _args[] = {
187		{0, UINT_MAX, "Invalid up interval"},
188		{0, UINT_MAX, "Invalid down interval"},
189	};
190
191	int r;
192	struct flakey_c *fc;
193	unsigned long long tmpll;
194	struct dm_arg_set as;
195	const char *devname;
196	char dummy;
197
198	as.argc = argc;
199	as.argv = argv;
200
201	if (argc < 4) {
202		ti->error = "Invalid argument count";
203		return -EINVAL;
204	}
205
206	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
207	if (!fc) {
208		ti->error = "Cannot allocate context";
209		return -ENOMEM;
210	}
211	fc->start_time = jiffies;
212
213	devname = dm_shift_arg(&as);
214
215	r = -EINVAL;
216	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
217		ti->error = "Invalid device sector";
218		goto bad;
219	}
220	fc->start = tmpll;
221
222	r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
223	if (r)
224		goto bad;
225
226	r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
227	if (r)
228		goto bad;
229
230	if (!(fc->up_interval + fc->down_interval)) {
231		ti->error = "Total (up + down) interval is zero";
232		r = -EINVAL;
233		goto bad;
234	}
235
236	if (fc->up_interval + fc->down_interval < fc->up_interval) {
237		ti->error = "Interval overflow";
238		r = -EINVAL;
239		goto bad;
240	}
241
242	r = parse_features(&as, fc, ti);
243	if (r)
244		goto bad;
245
246	r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
247	if (r) {
248		ti->error = "Device lookup failed";
249		goto bad;
250	}
251
252	ti->num_flush_bios = 1;
253	ti->num_discard_bios = 1;
254	ti->per_io_data_size = sizeof(struct per_bio_data);
255	ti->private = fc;
256	return 0;
257
258bad:
259	kfree(fc);
260	return r;
261}
262
263static void flakey_dtr(struct dm_target *ti)
264{
265	struct flakey_c *fc = ti->private;
266
267	dm_put_device(ti, fc->dev);
268	kfree(fc);
269}
270
271static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
272{
273	struct flakey_c *fc = ti->private;
274
275	return fc->start + dm_target_offset(ti, bi_sector);
276}
277
278static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
279{
280	struct flakey_c *fc = ti->private;
281
282	bio_set_dev(bio, fc->dev->bdev);
283	if (bio_sectors(bio) || op_is_zone_mgmt(bio_op(bio)))
284		bio->bi_iter.bi_sector =
285			flakey_map_sector(ti, bio->bi_iter.bi_sector);
286}
287
288static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
289{
290	unsigned int corrupt_bio_byte = fc->corrupt_bio_byte - 1;
291
292	struct bvec_iter iter;
293	struct bio_vec bvec;
294
295	if (!bio_has_data(bio))
296		return;
297
298	/*
299	 * Overwrite the Nth byte of the bio's data, on whichever page
300	 * it falls.
301	 */
302	bio_for_each_segment(bvec, bio, iter) {
303		if (bio_iter_len(bio, iter) > corrupt_bio_byte) {
304			char *segment = (page_address(bio_iter_page(bio, iter))
305					 + bio_iter_offset(bio, iter));
306			segment[corrupt_bio_byte] = fc->corrupt_bio_value;
307			DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
308				"(rw=%c bi_opf=%u bi_sector=%llu size=%u)\n",
309				bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
310				(bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
311				(unsigned long long)bio->bi_iter.bi_sector, bio->bi_iter.bi_size);
312			break;
313		}
314		corrupt_bio_byte -= bio_iter_len(bio, iter);
315	}
316}
317
318static int flakey_map(struct dm_target *ti, struct bio *bio)
319{
320	struct flakey_c *fc = ti->private;
321	unsigned elapsed;
322	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
323	pb->bio_submitted = false;
324
325	if (op_is_zone_mgmt(bio_op(bio)))
326		goto map_bio;
327
328	/* Are we alive ? */
329	elapsed = (jiffies - fc->start_time) / HZ;
330	if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
331		/*
332		 * Flag this bio as submitted while down.
333		 */
334		pb->bio_submitted = true;
335
336		/*
337		 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
338		 * Otherwise, flakey_end_io() will decide if the reads should be modified.
339		 */
340		if (bio_data_dir(bio) == READ) {
341			if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
342			    !test_bit(ERROR_WRITES, &fc->flags))
343				return DM_MAPIO_KILL;
344			goto map_bio;
345		}
346
347		/*
348		 * Drop or error writes?
349		 */
350		if (test_bit(DROP_WRITES, &fc->flags)) {
351			bio_endio(bio);
352			return DM_MAPIO_SUBMITTED;
353		}
354		else if (test_bit(ERROR_WRITES, &fc->flags)) {
355			bio_io_error(bio);
356			return DM_MAPIO_SUBMITTED;
357		}
358
359		/*
360		 * Corrupt matching writes.
361		 */
362		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
363			if (all_corrupt_bio_flags_match(bio, fc))
364				corrupt_bio_data(bio, fc);
365			goto map_bio;
366		}
367
368		/*
369		 * By default, error all I/O.
370		 */
371		return DM_MAPIO_KILL;
372	}
373
374map_bio:
375	flakey_map_bio(ti, bio);
376
377	return DM_MAPIO_REMAPPED;
378}
379
380static int flakey_end_io(struct dm_target *ti, struct bio *bio,
381			 blk_status_t *error)
382{
383	struct flakey_c *fc = ti->private;
384	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
385
386	if (op_is_zone_mgmt(bio_op(bio)))
387		return DM_ENDIO_DONE;
388
389	if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
390		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
391		    all_corrupt_bio_flags_match(bio, fc)) {
392			/*
393			 * Corrupt successful matching READs while in down state.
394			 */
395			corrupt_bio_data(bio, fc);
396
397		} else if (!test_bit(DROP_WRITES, &fc->flags) &&
398			   !test_bit(ERROR_WRITES, &fc->flags)) {
399			/*
400			 * Error read during the down_interval if drop_writes
401			 * and error_writes were not configured.
402			 */
403			*error = BLK_STS_IOERR;
404		}
405	}
406
407	return DM_ENDIO_DONE;
408}
409
410static void flakey_status(struct dm_target *ti, status_type_t type,
411			  unsigned status_flags, char *result, unsigned maxlen)
412{
413	unsigned sz = 0;
414	struct flakey_c *fc = ti->private;
415	unsigned drop_writes, error_writes;
416
417	switch (type) {
418	case STATUSTYPE_INFO:
419		result[0] = '\0';
420		break;
421
422	case STATUSTYPE_TABLE:
423		DMEMIT("%s %llu %u %u ", fc->dev->name,
424		       (unsigned long long)fc->start, fc->up_interval,
425		       fc->down_interval);
426
427		drop_writes = test_bit(DROP_WRITES, &fc->flags);
428		error_writes = test_bit(ERROR_WRITES, &fc->flags);
429		DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
430
431		if (drop_writes)
432			DMEMIT("drop_writes ");
433		else if (error_writes)
434			DMEMIT("error_writes ");
435
436		if (fc->corrupt_bio_byte)
437			DMEMIT("corrupt_bio_byte %u %c %u %u ",
438			       fc->corrupt_bio_byte,
439			       (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
440			       fc->corrupt_bio_value, fc->corrupt_bio_flags);
441
442		break;
443	}
444}
445
446static int flakey_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
447{
448	struct flakey_c *fc = ti->private;
449
450	*bdev = fc->dev->bdev;
451
452	/*
453	 * Only pass ioctls through if the device sizes match exactly.
454	 */
455	if (fc->start ||
456	    ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
457		return 1;
458	return 0;
459}
460
461#ifdef CONFIG_BLK_DEV_ZONED
462static int flakey_report_zones(struct dm_target *ti,
463		struct dm_report_zones_args *args, unsigned int nr_zones)
464{
465	struct flakey_c *fc = ti->private;
466	sector_t sector = flakey_map_sector(ti, args->next_sector);
467
468	args->start = fc->start;
469	return blkdev_report_zones(fc->dev->bdev, sector, nr_zones,
470				   dm_report_zones_cb, args);
471}
472#endif
473
474static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
475{
476	struct flakey_c *fc = ti->private;
477
478	return fn(ti, fc->dev, fc->start, ti->len, data);
479}
480
481static struct target_type flakey_target = {
482	.name   = "flakey",
483	.version = {1, 5, 0},
484#ifdef CONFIG_BLK_DEV_ZONED
485	.features = DM_TARGET_ZONED_HM,
486	.report_zones = flakey_report_zones,
487#endif
488	.module = THIS_MODULE,
489	.ctr    = flakey_ctr,
490	.dtr    = flakey_dtr,
491	.map    = flakey_map,
492	.end_io = flakey_end_io,
493	.status = flakey_status,
494	.prepare_ioctl = flakey_prepare_ioctl,
495	.iterate_devices = flakey_iterate_devices,
496};
497
498static int __init dm_flakey_init(void)
499{
500	int r = dm_register_target(&flakey_target);
501
502	if (r < 0)
503		DMERR("register failed %d", r);
504
505	return r;
506}
507
508static void __exit dm_flakey_exit(void)
509{
510	dm_unregister_target(&flakey_target);
511}
512
513/* Module hooks */
514module_init(dm_flakey_init);
515module_exit(dm_flakey_exit);
516
517MODULE_DESCRIPTION(DM_NAME " flakey target");
518MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
519MODULE_LICENSE("GPL");