[mirror_ubuntu-zesty-kernel.git] / drivers / md / dm-flakey.c

/*
 * Copyright (C) 2003 Sistina Software (UK) Limited.
 * Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
 *
 * This file is released under the GPL.
 */

#include <linux/device-mapper.h>

#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>

#define DM_MSG_PREFIX "flakey"

#define all_corrupt_bio_flags_match(bio, fc)	\
	(((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)

/*
 * Flakey: Used for testing only, simulates intermittent,
 * catastrophic device failure.
 */
struct flakey_c {
	struct dm_dev *dev;
	unsigned long start_time;
	sector_t start;
	unsigned up_interval;
	unsigned down_interval;
	unsigned long flags;
	unsigned corrupt_bio_byte;
	unsigned corrupt_bio_rw;
	unsigned corrupt_bio_value;
	unsigned corrupt_bio_flags;
};

enum feature_flag_bits {
	DROP_WRITES,
	ERROR_WRITES
};

struct per_bio_data {
	bool bio_submitted;
};

static int parse_features(struct dm_arg_set *as, struct flakey_c *fc,
			  struct dm_target *ti)
{
	int r;
	unsigned argc;
	const char *arg_name;

	static struct dm_arg _args[] = {
		{0, 6, "Invalid number of feature args"},
		{1, UINT_MAX, "Invalid corrupt bio byte"},
		{0, 255, "Invalid corrupt value to write into bio byte (0-255)"},
		{0, UINT_MAX, "Invalid corrupt bio flags mask"},
	};

	/* No feature arguments supplied. */
	if (!as->argc)
		return 0;

	r = dm_read_arg_group(_args, as, &argc, &ti->error);
	if (r)
		return r;

	while (argc) {
		arg_name = dm_shift_arg(as);
		argc--;

		/*
		 * drop_writes
		 */
		if (!strcasecmp(arg_name, "drop_writes")) {
			if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
				ti->error = "Feature drop_writes duplicated";
				return -EINVAL;
			} else if (test_bit(ERROR_WRITES, &fc->flags)) {
				ti->error = "Feature drop_writes conflicts with feature error_writes";
				return -EINVAL;
			}

			continue;
		}

		/*
		 * error_writes
		 */
		if (!strcasecmp(arg_name, "error_writes")) {
			if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
				ti->error = "Feature error_writes duplicated";
				return -EINVAL;

			} else if (test_bit(DROP_WRITES, &fc->flags)) {
				ti->error = "Feature error_writes conflicts with feature drop_writes";
				return -EINVAL;
			}

			continue;
		}

		/*
		 * corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
		 */
		if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
			if (!argc) {
				ti->error = "Feature corrupt_bio_byte requires parameters";
				return -EINVAL;
			}

			r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
			if (r)
				return r;
			argc--;

			/*
			 * Direction r or w?
			 */
			arg_name = dm_shift_arg(as);
			if (!strcasecmp(arg_name, "w"))
				fc->corrupt_bio_rw = WRITE;
			else if (!strcasecmp(arg_name, "r"))
				fc->corrupt_bio_rw = READ;
			else {
				ti->error = "Invalid corrupt bio direction (r or w)";
				return -EINVAL;
			}
			argc--;

			/*
			 * Value of byte (0-255) to write in place of correct one.
			 */
			r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
			if (r)
				return r;
			argc--;

			/*
			 * Only corrupt bios with these flags set.
			 */
			r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
			if (r)
				return r;
			argc--;

			continue;
		}

		ti->error = "Unrecognised flakey feature requested";
		return -EINVAL;
	}

	if (test_bit(DROP_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
		ti->error = "drop_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
		return -EINVAL;

	} else if (test_bit(ERROR_WRITES, &fc->flags) && (fc->corrupt_bio_rw == WRITE)) {
		ti->error = "error_writes is incompatible with corrupt_bio_byte with the WRITE flag set";
		return -EINVAL;
	}

	return 0;
}

/*
 * Construct a flakey mapping:
 * <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
 *
 *   Feature args:
 *     [drop_writes]
 *     [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
 *
 *   Nth_byte starts from 1 for the first byte.
 *   Direction is r for READ or w for WRITE.
 *   bio_flags is ignored if 0.
 */
static int flakey_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
	static struct dm_arg _args[] = {
		{0, UINT_MAX, "Invalid up interval"},
		{0, UINT_MAX, "Invalid down interval"},
	};

	int r;
	struct flakey_c *fc;
	unsigned long long tmpll;
	struct dm_arg_set as;
	const char *devname;
	char dummy;

	as.argc = argc;
	as.argv = argv;

	if (argc < 4) {
		ti->error = "Invalid argument count";
		return -EINVAL;
	}

	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
	if (!fc) {
		ti->error = "Cannot allocate context";
		return -ENOMEM;
	}
	fc->start_time = jiffies;

	devname = dm_shift_arg(&as);

	r = -EINVAL;
	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
		ti->error = "Invalid device sector";
		goto bad;
	}
	fc->start = tmpll;

	r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
	if (r)
		goto bad;

	r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
	if (r)
		goto bad;

	if (!(fc->up_interval + fc->down_interval)) {
		ti->error = "Total (up + down) interval is zero";
		r = -EINVAL;
		goto bad;
	}

	if (fc->up_interval + fc->down_interval < fc->up_interval) {
		ti->error = "Interval overflow";
		r = -EINVAL;
		goto bad;
	}

	r = parse_features(&as, fc, ti);
	if (r)
		goto bad;

	r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
	if (r) {
		ti->error = "Device lookup failed";
		goto bad;
	}

	ti->num_flush_bios = 1;
	ti->num_discard_bios = 1;
	ti->per_io_data_size = sizeof(struct per_bio_data);
	ti->private = fc;
	return 0;

bad:
	kfree(fc);
	return r;
}

static void flakey_dtr(struct dm_target *ti)
{
	struct flakey_c *fc = ti->private;

	dm_put_device(ti, fc->dev);
	kfree(fc);
}

static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
{
	struct flakey_c *fc = ti->private;

	return fc->start + dm_target_offset(ti, bi_sector);
}

static void flakey_map_bio(struct dm_target *ti, struct bio *bio)
{
	struct flakey_c *fc = ti->private;

	bio->bi_bdev = fc->dev->bdev;
	if (bio_sectors(bio))
		bio->bi_iter.bi_sector =
			flakey_map_sector(ti, bio->bi_iter.bi_sector);
}

static void corrupt_bio_data(struct bio *bio, struct flakey_c *fc)
{
	unsigned bio_bytes = bio_cur_bytes(bio);
	char *data = bio_data(bio);

	/*
	 * Overwrite the Nth byte of the data returned.
	 */
	if (data && bio_bytes >= fc->corrupt_bio_byte) {
		data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;

		DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
			"(rw=%c bi_opf=%u bi_sector=%llu cur_bytes=%u)\n",
			bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
			(bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
			(unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
	}
}

static int flakey_map(struct dm_target *ti, struct bio *bio)
{
	struct flakey_c *fc = ti->private;
	unsigned elapsed;
	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
	pb->bio_submitted = false;

	/* Are we alive ? */
	elapsed = (jiffies - fc->start_time) / HZ;
	if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
		/*
		 * Flag this bio as submitted while down.
		 */
		pb->bio_submitted = true;

		/*
		 * Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
		 * Otherwise, flakey_end_io() will decide if the reads should be modified.
		 */
		if (bio_data_dir(bio) == READ) {
			if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
			    !test_bit(ERROR_WRITES, &fc->flags))
				return -EIO;
			goto map_bio;
		}

		/*
		 * Drop or error writes?
		 */
		if (test_bit(DROP_WRITES, &fc->flags)) {
			bio_endio(bio);
			return DM_MAPIO_SUBMITTED;
		}
		else if (test_bit(ERROR_WRITES, &fc->flags)) {
			bio_io_error(bio);
			return DM_MAPIO_SUBMITTED;
		}

		/*
		 * Corrupt matching writes.
		 */
		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
			if (all_corrupt_bio_flags_match(bio, fc))
				corrupt_bio_data(bio, fc);
			goto map_bio;
		}

		/*
		 * By default, error all I/O.
		 */
		return -EIO;
	}

map_bio:
	flakey_map_bio(ti, bio);

	return DM_MAPIO_REMAPPED;
}

static int flakey_end_io(struct dm_target *ti, struct bio *bio, int error)
{
	struct flakey_c *fc = ti->private;
	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));

	if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
		    all_corrupt_bio_flags_match(bio, fc)) {
			/*
			 * Corrupt successful matching READs while in down state.
			 */
			corrupt_bio_data(bio, fc);

		} else if (!test_bit(DROP_WRITES, &fc->flags) &&
			   !test_bit(ERROR_WRITES, &fc->flags)) {
			/*
			 * Error read during the down_interval if drop_writes
			 * and error_writes were not configured.
			 */
			return -EIO;
		}
	}

	return error;
}

static void flakey_status(struct dm_target *ti, status_type_t type,
			  unsigned status_flags, char *result, unsigned maxlen)
{
	unsigned sz = 0;
	struct flakey_c *fc = ti->private;
	unsigned drop_writes, error_writes;

	switch (type) {
	case STATUSTYPE_INFO:
		result[0] = '\0';
		break;

	case STATUSTYPE_TABLE:
		DMEMIT("%s %llu %u %u ", fc->dev->name,
		       (unsigned long long)fc->start, fc->up_interval,
		       fc->down_interval);

		drop_writes = test_bit(DROP_WRITES, &fc->flags);
		error_writes = test_bit(ERROR_WRITES, &fc->flags);
		DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);

		if (drop_writes)
			DMEMIT("drop_writes ");
		else if (error_writes)
			DMEMIT("error_writes ");

		if (fc->corrupt_bio_byte)
			DMEMIT("corrupt_bio_byte %u %c %u %u ",
			       fc->corrupt_bio_byte,
			       (fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
			       fc->corrupt_bio_value, fc->corrupt_bio_flags);

		break;
	}
}

static int flakey_prepare_ioctl(struct dm_target *ti,
		struct block_device **bdev, fmode_t *mode)
{
	struct flakey_c *fc = ti->private;

	*bdev = fc->dev->bdev;

	/*
	 * Only pass ioctls through if the device sizes match exactly.
	 */
	if (fc->start ||
	    ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
		return 1;
	return 0;
}

static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
{
	struct flakey_c *fc = ti->private;

	return fn(ti, fc->dev, fc->start, ti->len, data);
}

static struct target_type flakey_target = {
	.name   = "flakey",
	.version = {1, 4, 0},
	.module = THIS_MODULE,
	.ctr    = flakey_ctr,
	.dtr    = flakey_dtr,
	.map    = flakey_map,
	.end_io = flakey_end_io,
	.status = flakey_status,
	.prepare_ioctl = flakey_prepare_ioctl,
	.iterate_devices = flakey_iterate_devices,
};

static int __init dm_flakey_init(void)
{
	int r = dm_register_target(&flakey_target);

	if (r < 0)
		DMERR("register failed %d", r);

	return r;
}

static void __exit dm_flakey_exit(void)
{
	dm_unregister_target(&flakey_target);
}

/* Module hooks */
module_init(dm_flakey_init);
module_exit(dm_flakey_exit);

MODULE_DESCRIPTION(DM_NAME " flakey target");
MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
MODULE_LICENSE("GPL");
Commit	Line	Data
3407ef52 JB	1	/*
3407ef52 JB	2	* Copyright (C) 2003 Sistina Software (UK) Limited.
a3998799	3	* Copyright (C) 2004, 2010-2011 Red Hat, Inc. All rights reserved.
3407ef52 JB	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
a3998799	18	#define all_corrupt_bio_flags_match(bio, fc) \
1eff9d32	19	(((bio)->bi_opf & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
a3998799	20
3407ef52 JB	21	/*
	22	* Flakey: Used for testing only, simulates intermittent,
	23	* catastrophic device failure.
	24	*/
	25	struct flakey_c {
	26	struct dm_dev *dev;
	27	unsigned long start_time;
	28	sector_t start;
	29	unsigned up_interval;
	30	unsigned down_interval;
b26f5e3d	31	unsigned long flags;
a3998799 MS	32	unsigned corrupt_bio_byte;
	33	unsigned corrupt_bio_rw;
	34	unsigned corrupt_bio_value;
	35	unsigned corrupt_bio_flags;
3407ef52 JB	36	};
3407ef52 JB	37
b26f5e3d	38	enum feature_flag_bits {
ef548c55 MS	39	DROP_WRITES,
ef548c55 MS	40	ERROR_WRITES
b26f5e3d MS	41	};
b26f5e3d MS	42
c7cfdf59 MP	43	struct per_bio_data {
	44	bool bio_submitted;
	45	};
	46
b26f5e3d MS	47	static int parse_features(struct dm_arg_set as, struct flakey_c fc,
b26f5e3d MS	48	struct dm_target *ti)
dfd068b0 MS	49	{
	50	int r;
	51	unsigned argc;
	52	const char *arg_name;
	53
	54	static struct dm_arg _args[] = {
a3998799 MS	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"},
dfd068b0 MS	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)
a3998799	67	return r;
dfd068b0	68
a3998799	69	while (argc) {
dfd068b0 MS	70	arg_name = dm_shift_arg(as);
	71	argc--;
	72
b26f5e3d MS	73	/*
	74	* drop_writes
	75	*/
	76	if (!strcasecmp(arg_name, "drop_writes")) {
	77	if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
	78	ti->error = "Feature drop_writes duplicated";
	79	return -EINVAL;
ef548c55 MS	80	} else if (test_bit(ERROR_WRITES, &fc->flags)) {
	81	ti->error = "Feature drop_writes conflicts with feature error_writes";
	82	return -EINVAL;
	83	}
	84
	85	continue;
	86	}
	87
	88	/*
	89	* error_writes
	90	*/
	91	if (!strcasecmp(arg_name, "error_writes")) {
	92	if (test_and_set_bit(ERROR_WRITES, &fc->flags)) {
	93	ti->error = "Feature error_writes duplicated";
	94	return -EINVAL;
	95
	96	} else if (test_bit(DROP_WRITES, &fc->flags)) {
	97	ti->error = "Feature error_writes conflicts with feature drop_writes";
	98	return -EINVAL;
b26f5e3d MS	99	}
	100
	101	continue;
	102	}
	103
a3998799 MS	104	/*
	105	* corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
	106	*/
	107	if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
68e58a29	108	if (!argc) {
a3998799	109	ti->error = "Feature corrupt_bio_byte requires parameters";
68e58a29 MS	110	return -EINVAL;
68e58a29 MS	111	}
a3998799 MS	112
	113	r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
	114	if (r)
	115	return r;
	116	argc--;
	117
	118	/*
	119	* Direction r or w?
	120	*/
	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;
	126	else {
	127	ti->error = "Invalid corrupt bio direction (r or w)";
	128	return -EINVAL;
	129	}
	130	argc--;
	131
	132	/*
	133	* Value of byte (0-255) to write in place of correct one.
	134	*/
	135	r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
	136	if (r)
	137	return r;
	138	argc--;
	139
	140	/*
	141	* Only corrupt bios with these flags set.
	142	*/
	143	r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
	144	if (r)
	145	return r;
	146	argc--;
	147
	148	continue;
	149	}
	150
dfd068b0	151	ti->error = "Unrecognised flakey feature requested";
a3998799	152	return -EINVAL;
dfd068b0 MS	153	}
dfd068b0 MS	154
a3998799 MS	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";
	157	return -EINVAL;
ef548c55 MS	158
	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";
	161	return -EINVAL;
a3998799 MS	162	}
	163
	164	return 0;
dfd068b0 MS	165	}
dfd068b0 MS	166
3407ef52	167	/*
dfd068b0 MS	168	* Construct a flakey mapping:
dfd068b0 MS	169	* <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
b26f5e3d MS	170	*
	171	* Feature args:
	172	* [drop_writes]
a3998799 MS	173	* [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
	174	*
	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.
3407ef52 JB	178	*/
	179	static int flakey_ctr(struct dm_target ti, unsigned int argc, char *argv)
	180	{
dfd068b0 MS	181	static struct dm_arg _args[] = {
	182	{0, UINT_MAX, "Invalid up interval"},
	183	{0, UINT_MAX, "Invalid down interval"},
	184	};
	185
	186	int r;
3407ef52	187	struct flakey_c *fc;
dfd068b0 MS	188	unsigned long long tmpll;
	189	struct dm_arg_set as;
	190	const char *devname;
31998ef1	191	char dummy;
3407ef52	192
dfd068b0 MS	193	as.argc = argc;
	194	as.argv = argv;
	195
	196	if (argc < 4) {
	197	ti->error = "Invalid argument count";
3407ef52 JB	198	return -EINVAL;
	199	}
	200
b26f5e3d	201	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
3407ef52	202	if (!fc) {
75e3a0f5	203	ti->error = "Cannot allocate context";
3407ef52 JB	204	return -ENOMEM;
	205	}
	206	fc->start_time = jiffies;
	207
dfd068b0 MS	208	devname = dm_shift_arg(&as);
dfd068b0 MS	209
e80d1c80	210	r = -EINVAL;
31998ef1	211	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
dfd068b0	212	ti->error = "Invalid device sector";
3407ef52 JB	213	goto bad;
3407ef52 JB	214	}
dfd068b0	215	fc->start = tmpll;
3407ef52	216
dfd068b0 MS	217	r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
dfd068b0 MS	218	if (r)
3407ef52	219	goto bad;
3407ef52	220
dfd068b0 MS	221	r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
dfd068b0 MS	222	if (r)
3407ef52	223	goto bad;
3407ef52 JB	224
3407ef52 JB	225	if (!(fc->up_interval + fc->down_interval)) {
dfd068b0	226	ti->error = "Total (up + down) interval is zero";
bff7e067	227	r = -EINVAL;
3407ef52 JB	228	goto bad;
	229	}
	230
	231	if (fc->up_interval + fc->down_interval < fc->up_interval) {
dfd068b0	232	ti->error = "Interval overflow";
bff7e067	233	r = -EINVAL;
3407ef52 JB	234	goto bad;
	235	}
	236
b26f5e3d	237	r = parse_features(&as, fc, ti);
dfd068b0 MS	238	if (r)
	239	goto bad;
	240
e80d1c80 VG	241	r = dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev);
e80d1c80 VG	242	if (r) {
dfd068b0	243	ti->error = "Device lookup failed";
3407ef52 JB	244	goto bad;
	245	}
	246
55a62eef AK	247	ti->num_flush_bios = 1;
55a62eef AK	248	ti->num_discard_bios = 1;
30187e1d	249	ti->per_io_data_size = sizeof(struct per_bio_data);
3407ef52 JB	250	ti->private = fc;
	251	return 0;
	252
	253	bad:
	254	kfree(fc);
e80d1c80	255	return r;
3407ef52 JB	256	}
	257
	258	static void flakey_dtr(struct dm_target *ti)
	259	{
	260	struct flakey_c *fc = ti->private;
	261
	262	dm_put_device(ti, fc->dev);
	263	kfree(fc);
	264	}
	265
	266	static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
	267	{
	268	struct flakey_c *fc = ti->private;
	269
30e4171b	270	return fc->start + dm_target_offset(ti, bi_sector);
3407ef52 JB	271	}
	272
	273	static void flakey_map_bio(struct dm_target ti, struct bio bio)
	274	{
	275	struct flakey_c *fc = ti->private;
	276
	277	bio->bi_bdev = fc->dev->bdev;
	278	if (bio_sectors(bio))
4f024f37 KO	279	bio->bi_iter.bi_sector =
4f024f37 KO	280	flakey_map_sector(ti, bio->bi_iter.bi_sector);
3407ef52 JB	281	}
3407ef52 JB	282
a3998799 MS	283	static void corrupt_bio_data(struct bio bio, struct flakey_c fc)
	284	{
	285	unsigned bio_bytes = bio_cur_bytes(bio);
	286	char *data = bio_data(bio);
	287
	288	/*
	289	* Overwrite the Nth byte of the data returned.
	290	*/
	291	if (data && bio_bytes >= fc->corrupt_bio_byte) {
	292	data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
	293
	294	DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
1eff9d32	295	"(rw=%c bi_opf=%u bi_sector=%llu cur_bytes=%u)\n",
a3998799	296	bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
1eff9d32	297	(bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_opf,
4f024f37	298	(unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
a3998799 MS	299	}
	300	}
	301
7de3ee57	302	static int flakey_map(struct dm_target ti, struct bio bio)
3407ef52 JB	303	{
	304	struct flakey_c *fc = ti->private;
	305	unsigned elapsed;
c7cfdf59 MP	306	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
c7cfdf59 MP	307	pb->bio_submitted = false;
3407ef52 JB	308
	309	/* Are we alive ? */
	310	elapsed = (jiffies - fc->start_time) / HZ;
b26f5e3d	311	if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
a3998799 MS	312	/*
	313	* Flag this bio as submitted while down.
	314	*/
c7cfdf59	315	pb->bio_submitted = true;
a3998799 MS	316
a3998799 MS	317	/*
ef548c55	318	* Error reads if neither corrupt_bio_byte or drop_writes or error_writes are set.
299f6230	319	* Otherwise, flakey_end_io() will decide if the reads should be modified.
a3998799	320	*/
99f3c90d	321	if (bio_data_dir(bio) == READ) {
ef548c55 MS	322	if (!fc->corrupt_bio_byte && !test_bit(DROP_WRITES, &fc->flags) &&
ef548c55 MS	323	!test_bit(ERROR_WRITES, &fc->flags))
99f3c90d	324	return -EIO;
299f6230	325	goto map_bio;
99f3c90d	326	}
b26f5e3d MS	327
b26f5e3d MS	328	/*
ef548c55	329	* Drop or error writes?
b26f5e3d MS	330	*/
b26f5e3d MS	331	if (test_bit(DROP_WRITES, &fc->flags)) {
4246a0b6	332	bio_endio(bio);
a3998799 MS	333	return DM_MAPIO_SUBMITTED;
a3998799 MS	334	}
ef548c55 MS	335	else if (test_bit(ERROR_WRITES, &fc->flags)) {
	336	bio_io_error(bio);
	337	return DM_MAPIO_SUBMITTED;
	338	}
a3998799 MS	339
	340	/*
	341	* Corrupt matching writes.
	342	*/
	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);
b26f5e3d MS	346	goto map_bio;
	347	}
	348
	349	/*
a3998799	350	* By default, error all I/O.
b26f5e3d	351	*/
3407ef52	352	return -EIO;
b26f5e3d	353	}
3407ef52	354
b26f5e3d	355	map_bio:
3407ef52 JB	356	flakey_map_bio(ti, bio);
	357
	358	return DM_MAPIO_REMAPPED;
	359	}
	360
7de3ee57	361	static int flakey_end_io(struct dm_target ti, struct bio bio, int error)
a3998799 MS	362	{
a3998799 MS	363	struct flakey_c *fc = ti->private;
c7cfdf59	364	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
a3998799	365
99f3c90d	366	if (!error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
299f6230 MS	367	if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
	368	all_corrupt_bio_flags_match(bio, fc)) {
	369	/*
	370	* Corrupt successful matching READs while in down state.
	371	*/
99f3c90d	372	corrupt_bio_data(bio, fc);
299f6230	373
ef548c55 MS	374	} else if (!test_bit(DROP_WRITES, &fc->flags) &&
ef548c55 MS	375	!test_bit(ERROR_WRITES, &fc->flags)) {
299f6230 MS	376	/*
299f6230 MS	377	* Error read during the down_interval if drop_writes
ef548c55	378	* and error_writes were not configured.
299f6230	379	*/
99f3c90d	380	return -EIO;
299f6230	381	}
99f3c90d	382	}
a3998799 MS	383
	384	return error;
	385	}
	386
fd7c092e MP	387	static void flakey_status(struct dm_target *ti, status_type_t type,
fd7c092e MP	388	unsigned status_flags, char *result, unsigned maxlen)
3407ef52	389	{
b26f5e3d	390	unsigned sz = 0;
3407ef52	391	struct flakey_c *fc = ti->private;
ef548c55	392	unsigned drop_writes, error_writes;
3407ef52 JB	393
	394	switch (type) {
	395	case STATUSTYPE_INFO:
	396	result[0] = '\0';
	397	break;
	398
	399	case STATUSTYPE_TABLE:
b26f5e3d MS	400	DMEMIT("%s %llu %u %u ", fc->dev->name,
	401	(unsigned long long)fc->start, fc->up_interval,
	402	fc->down_interval);
	403
	404	drop_writes = test_bit(DROP_WRITES, &fc->flags);
ef548c55 MS	405	error_writes = test_bit(ERROR_WRITES, &fc->flags);
ef548c55 MS	406	DMEMIT("%u ", drop_writes + error_writes + (fc->corrupt_bio_byte > 0) * 5);
a3998799	407
b26f5e3d MS	408	if (drop_writes)
b26f5e3d MS	409	DMEMIT("drop_writes ");
ef548c55 MS	410	else if (error_writes)
ef548c55 MS	411	DMEMIT("error_writes ");
a3998799 MS	412
	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);
	418
3407ef52 JB	419	break;
3407ef52 JB	420	}
3407ef52 JB	421	}
3407ef52 JB	422
e56f81e0 CH	423	static int flakey_prepare_ioctl(struct dm_target *ti,
e56f81e0 CH	424	struct block_device *bdev, fmode_t mode)
3407ef52 JB	425	{
3407ef52 JB	426	struct flakey_c *fc = ti->private;
e56f81e0 CH	427
e56f81e0 CH	428	*bdev = fc->dev->bdev;
3407ef52	429
ec8013be PB	430	/*
	431	* Only pass ioctls through if the device sizes match exactly.
	432	*/
	433	if (fc->start \|\|
e56f81e0 CH	434	ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
	435	return 1;
	436	return 0;
3407ef52 JB	437	}
3407ef52 JB	438
3407ef52 JB	439	static int flakey_iterate_devices(struct dm_target ti, iterate_devices_callout_fn fn, void data)
	440	{
	441	struct flakey_c *fc = ti->private;
	442
	443	return fn(ti, fc->dev, fc->start, ti->len, data);
	444	}
	445
	446	static struct target_type flakey_target = {
	447	.name = "flakey",
ef548c55	448	.version = {1, 4, 0},
3407ef52 JB	449	.module = THIS_MODULE,
	450	.ctr = flakey_ctr,
	451	.dtr = flakey_dtr,
	452	.map = flakey_map,
a3998799	453	.end_io = flakey_end_io,
3407ef52	454	.status = flakey_status,
e56f81e0	455	.prepare_ioctl = flakey_prepare_ioctl,
3407ef52 JB	456	.iterate_devices = flakey_iterate_devices,
	457	};
	458
	459	static int __init dm_flakey_init(void)
	460	{
	461	int r = dm_register_target(&flakey_target);
	462
	463	if (r < 0)
	464	DMERR("register failed %d", r);
	465
	466	return r;
	467	}
	468
	469	static void __exit dm_flakey_exit(void)
	470	{
	471	dm_unregister_target(&flakey_target);
	472	}
	473
	474	/* Module hooks */
	475	module_init(dm_flakey_init);
	476	module_exit(dm_flakey_exit);
	477
	478	MODULE_DESCRIPTION(DM_NAME " flakey target");
	479	MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
	480	MODULE_LICENSE("GPL");