[mirror_ubuntu-artful-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_rw & (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
};

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;
			}

			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;
	}

	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);

	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";
		goto bad;
	}

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

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

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

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

bad:
	kfree(fc);
	return -EINVAL;
}

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_rw=%lu 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_rw,
			(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;

		/*
		 * Map reads as normal.
		 */
		if (bio_data_dir(bio) == READ)
			goto map_bio;

		/*
		 * Drop writes?
		 */
		if (test_bit(DROP_WRITES, &fc->flags)) {
			bio_endio(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));

	/*
	 * Corrupt successful READs while in down state.
	 * If flags were specified, only corrupt those that match.
	 */
	if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
	    (bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
	    all_corrupt_bio_flags_match(bio, fc))
		corrupt_bio_data(bio, fc);

	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;

	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);
		DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);

		if (drop_writes)
			DMEMIT("drop_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_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
{
	struct flakey_c *fc = ti->private;
	struct dm_dev *dev = fc->dev;
	int r = 0;

	/*
	 * Only pass ioctls through if the device sizes match exactly.
	 */
	if (fc->start ||
	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
		r = scsi_verify_blk_ioctl(NULL, cmd);

	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
}

static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
			struct bio_vec *biovec, int max_size)
{
	struct flakey_c *fc = ti->private;
	struct request_queue *q = bdev_get_queue(fc->dev->bdev);

	if (!q->merge_bvec_fn)
		return max_size;

	bvm->bi_bdev = fc->dev->bdev;
	bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);

	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
}

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, 3, 1},
	.module = THIS_MODULE,
	.ctr    = flakey_ctr,
	.dtr    = flakey_dtr,
	.map    = flakey_map,
	.end_io = flakey_end_io,
	.status = flakey_status,
	.ioctl	= flakey_ioctl,
	.merge	= flakey_merge,
	.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 MS	18	#define all_corrupt_bio_flags_match(bio, fc) \
	19	(((bio)->bi_rw & (fc)->corrupt_bio_flags) == (fc)->corrupt_bio_flags)
	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 MS	38	enum feature_flag_bits {
	39	DROP_WRITES
	40	};
	41
c7cfdf59 MP	42	struct per_bio_data {
	43	bool bio_submitted;
	44	};
	45
b26f5e3d MS	46	static int parse_features(struct dm_arg_set as, struct flakey_c fc,
b26f5e3d MS	47	struct dm_target *ti)
dfd068b0 MS	48	{
	49	int r;
	50	unsigned argc;
	51	const char *arg_name;
	52
	53	static struct dm_arg _args[] = {
a3998799 MS	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"},
dfd068b0 MS	58	};
	59
	60	/* No feature arguments supplied. */
	61	if (!as->argc)
	62	return 0;
	63
	64	r = dm_read_arg_group(_args, as, &argc, &ti->error);
	65	if (r)
a3998799	66	return r;
dfd068b0	67
a3998799	68	while (argc) {
dfd068b0 MS	69	arg_name = dm_shift_arg(as);
	70	argc--;
	71
b26f5e3d MS	72	/*
	73	* drop_writes
	74	*/
	75	if (!strcasecmp(arg_name, "drop_writes")) {
	76	if (test_and_set_bit(DROP_WRITES, &fc->flags)) {
	77	ti->error = "Feature drop_writes duplicated";
	78	return -EINVAL;
	79	}
	80
	81	continue;
	82	}
	83
a3998799 MS	84	/*
	85	* corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>
	86	*/
	87	if (!strcasecmp(arg_name, "corrupt_bio_byte")) {
68e58a29	88	if (!argc) {
a3998799	89	ti->error = "Feature corrupt_bio_byte requires parameters";
68e58a29 MS	90	return -EINVAL;
68e58a29 MS	91	}
a3998799 MS	92
	93	r = dm_read_arg(_args + 1, as, &fc->corrupt_bio_byte, &ti->error);
	94	if (r)
	95	return r;
	96	argc--;
	97
	98	/*
	99	* Direction r or w?
	100	*/
	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;
	106	else {
	107	ti->error = "Invalid corrupt bio direction (r or w)";
	108	return -EINVAL;
	109	}
	110	argc--;
	111
	112	/*
	113	* Value of byte (0-255) to write in place of correct one.
	114	*/
	115	r = dm_read_arg(_args + 2, as, &fc->corrupt_bio_value, &ti->error);
	116	if (r)
	117	return r;
	118	argc--;
	119
	120	/*
	121	* Only corrupt bios with these flags set.
	122	*/
	123	r = dm_read_arg(_args + 3, as, &fc->corrupt_bio_flags, &ti->error);
	124	if (r)
	125	return r;
	126	argc--;
	127
	128	continue;
	129	}
	130
dfd068b0	131	ti->error = "Unrecognised flakey feature requested";
a3998799	132	return -EINVAL;
dfd068b0 MS	133	}
dfd068b0 MS	134
a3998799 MS	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";
	137	return -EINVAL;
	138	}
	139
	140	return 0;
dfd068b0 MS	141	}
dfd068b0 MS	142
3407ef52	143	/*
dfd068b0 MS	144	* Construct a flakey mapping:
dfd068b0 MS	145	* <dev_path> <offset> <up interval> <down interval> [<#feature args> [<arg>]*]
b26f5e3d MS	146	*
	147	* Feature args:
	148	* [drop_writes]
a3998799 MS	149	* [corrupt_bio_byte <Nth_byte> <direction> <value> <bio_flags>]
	150	*
	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.
3407ef52 JB	154	*/
	155	static int flakey_ctr(struct dm_target ti, unsigned int argc, char *argv)
	156	{
dfd068b0 MS	157	static struct dm_arg _args[] = {
	158	{0, UINT_MAX, "Invalid up interval"},
	159	{0, UINT_MAX, "Invalid down interval"},
	160	};
	161
	162	int r;
3407ef52	163	struct flakey_c *fc;
dfd068b0 MS	164	unsigned long long tmpll;
	165	struct dm_arg_set as;
	166	const char *devname;
31998ef1	167	char dummy;
3407ef52	168
dfd068b0 MS	169	as.argc = argc;
	170	as.argv = argv;
	171
	172	if (argc < 4) {
	173	ti->error = "Invalid argument count";
3407ef52 JB	174	return -EINVAL;
	175	}
	176
b26f5e3d	177	fc = kzalloc(sizeof(*fc), GFP_KERNEL);
3407ef52	178	if (!fc) {
75e3a0f5	179	ti->error = "Cannot allocate context";
3407ef52 JB	180	return -ENOMEM;
	181	}
	182	fc->start_time = jiffies;
	183
dfd068b0 MS	184	devname = dm_shift_arg(&as);
dfd068b0 MS	185
31998ef1	186	if (sscanf(dm_shift_arg(&as), "%llu%c", &tmpll, &dummy) != 1) {
dfd068b0	187	ti->error = "Invalid device sector";
3407ef52 JB	188	goto bad;
3407ef52 JB	189	}
dfd068b0	190	fc->start = tmpll;
3407ef52	191
dfd068b0 MS	192	r = dm_read_arg(_args, &as, &fc->up_interval, &ti->error);
dfd068b0 MS	193	if (r)
3407ef52	194	goto bad;
3407ef52	195
dfd068b0 MS	196	r = dm_read_arg(_args, &as, &fc->down_interval, &ti->error);
dfd068b0 MS	197	if (r)
3407ef52	198	goto bad;
3407ef52 JB	199
3407ef52 JB	200	if (!(fc->up_interval + fc->down_interval)) {
dfd068b0	201	ti->error = "Total (up + down) interval is zero";
3407ef52 JB	202	goto bad;
	203	}
	204
	205	if (fc->up_interval + fc->down_interval < fc->up_interval) {
dfd068b0	206	ti->error = "Interval overflow";
3407ef52 JB	207	goto bad;
	208	}
	209
b26f5e3d	210	r = parse_features(&as, fc, ti);
dfd068b0 MS	211	if (r)
	212	goto bad;
	213
	214	if (dm_get_device(ti, devname, dm_table_get_mode(ti->table), &fc->dev)) {
	215	ti->error = "Device lookup failed";
3407ef52 JB	216	goto bad;
	217	}
	218
55a62eef AK	219	ti->num_flush_bios = 1;
55a62eef AK	220	ti->num_discard_bios = 1;
c7cfdf59	221	ti->per_bio_data_size = sizeof(struct per_bio_data);
3407ef52 JB	222	ti->private = fc;
	223	return 0;
	224
	225	bad:
	226	kfree(fc);
	227	return -EINVAL;
	228	}
	229
	230	static void flakey_dtr(struct dm_target *ti)
	231	{
	232	struct flakey_c *fc = ti->private;
	233
	234	dm_put_device(ti, fc->dev);
	235	kfree(fc);
	236	}
	237
	238	static sector_t flakey_map_sector(struct dm_target *ti, sector_t bi_sector)
	239	{
	240	struct flakey_c *fc = ti->private;
	241
30e4171b	242	return fc->start + dm_target_offset(ti, bi_sector);
3407ef52 JB	243	}
	244
	245	static void flakey_map_bio(struct dm_target ti, struct bio bio)
	246	{
	247	struct flakey_c *fc = ti->private;
	248
	249	bio->bi_bdev = fc->dev->bdev;
	250	if (bio_sectors(bio))
4f024f37 KO	251	bio->bi_iter.bi_sector =
4f024f37 KO	252	flakey_map_sector(ti, bio->bi_iter.bi_sector);
3407ef52 JB	253	}
3407ef52 JB	254
a3998799 MS	255	static void corrupt_bio_data(struct bio bio, struct flakey_c fc)
	256	{
	257	unsigned bio_bytes = bio_cur_bytes(bio);
	258	char *data = bio_data(bio);
	259
	260	/*
	261	* Overwrite the Nth byte of the data returned.
	262	*/
	263	if (data && bio_bytes >= fc->corrupt_bio_byte) {
	264	data[fc->corrupt_bio_byte - 1] = fc->corrupt_bio_value;
	265
	266	DMDEBUG("Corrupting data bio=%p by writing %u to byte %u "
	267	"(rw=%c bi_rw=%lu bi_sector=%llu cur_bytes=%u)\n",
	268	bio, fc->corrupt_bio_value, fc->corrupt_bio_byte,
4f024f37 KO	269	(bio_data_dir(bio) == WRITE) ? 'w' : 'r', bio->bi_rw,
4f024f37 KO	270	(unsigned long long)bio->bi_iter.bi_sector, bio_bytes);
a3998799 MS	271	}
	272	}
	273
7de3ee57	274	static int flakey_map(struct dm_target ti, struct bio bio)
3407ef52 JB	275	{
	276	struct flakey_c *fc = ti->private;
	277	unsigned elapsed;
c7cfdf59 MP	278	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
c7cfdf59 MP	279	pb->bio_submitted = false;
3407ef52 JB	280
	281	/* Are we alive ? */
	282	elapsed = (jiffies - fc->start_time) / HZ;
b26f5e3d	283	if (elapsed % (fc->up_interval + fc->down_interval) >= fc->up_interval) {
a3998799 MS	284	/*
	285	* Flag this bio as submitted while down.
	286	*/
c7cfdf59	287	pb->bio_submitted = true;
a3998799 MS	288
	289	/*
	290	* Map reads as normal.
	291	*/
	292	if (bio_data_dir(bio) == READ)
	293	goto map_bio;
b26f5e3d MS	294
b26f5e3d MS	295	/*
a3998799	296	* Drop writes?
b26f5e3d MS	297	*/
b26f5e3d MS	298	if (test_bit(DROP_WRITES, &fc->flags)) {
4246a0b6	299	bio_endio(bio);
a3998799 MS	300	return DM_MAPIO_SUBMITTED;
	301	}
	302
	303	/*
	304	* Corrupt matching writes.
	305	*/
	306	if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == WRITE)) {
	307	if (all_corrupt_bio_flags_match(bio, fc))
	308	corrupt_bio_data(bio, fc);
b26f5e3d MS	309	goto map_bio;
	310	}
	311
	312	/*
a3998799	313	* By default, error all I/O.
b26f5e3d	314	*/
3407ef52	315	return -EIO;
b26f5e3d	316	}
3407ef52	317
b26f5e3d	318	map_bio:
3407ef52 JB	319	flakey_map_bio(ti, bio);
	320
	321	return DM_MAPIO_REMAPPED;
	322	}
	323
7de3ee57	324	static int flakey_end_io(struct dm_target ti, struct bio bio, int error)
a3998799 MS	325	{
a3998799 MS	326	struct flakey_c *fc = ti->private;
c7cfdf59	327	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
a3998799 MS	328
	329	/*
	330	* Corrupt successful READs while in down state.
	331	* If flags were specified, only corrupt those that match.
	332	*/
c7cfdf59	333	if (fc->corrupt_bio_byte && !error && pb->bio_submitted &&
a3998799 MS	334	(bio_data_dir(bio) == READ) && (fc->corrupt_bio_rw == READ) &&
	335	all_corrupt_bio_flags_match(bio, fc))
	336	corrupt_bio_data(bio, fc);
	337
	338	return error;
	339	}
	340
fd7c092e MP	341	static void flakey_status(struct dm_target *ti, status_type_t type,
fd7c092e MP	342	unsigned status_flags, char *result, unsigned maxlen)
3407ef52	343	{
b26f5e3d	344	unsigned sz = 0;
3407ef52	345	struct flakey_c *fc = ti->private;
b26f5e3d	346	unsigned drop_writes;
3407ef52 JB	347
	348	switch (type) {
	349	case STATUSTYPE_INFO:
	350	result[0] = '\0';
	351	break;
	352
	353	case STATUSTYPE_TABLE:
b26f5e3d MS	354	DMEMIT("%s %llu %u %u ", fc->dev->name,
	355	(unsigned long long)fc->start, fc->up_interval,
	356	fc->down_interval);
	357
	358	drop_writes = test_bit(DROP_WRITES, &fc->flags);
a3998799 MS	359	DMEMIT("%u ", drop_writes + (fc->corrupt_bio_byte > 0) * 5);
a3998799 MS	360
b26f5e3d MS	361	if (drop_writes)
b26f5e3d MS	362	DMEMIT("drop_writes ");
a3998799 MS	363
	364	if (fc->corrupt_bio_byte)
	365	DMEMIT("corrupt_bio_byte %u %c %u %u ",
	366	fc->corrupt_bio_byte,
	367	(fc->corrupt_bio_rw == WRITE) ? 'w' : 'r',
	368	fc->corrupt_bio_value, fc->corrupt_bio_flags);
	369
3407ef52 JB	370	break;
3407ef52 JB	371	}
3407ef52 JB	372	}
	373
	374	static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
	375	{
	376	struct flakey_c *fc = ti->private;
ec8013be PB	377	struct dm_dev *dev = fc->dev;
ec8013be PB	378	int r = 0;
3407ef52	379
ec8013be PB	380	/*
	381	* Only pass ioctls through if the device sizes match exactly.
	382	*/
	383	if (fc->start \|\|
	384	ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
	385	r = scsi_verify_blk_ioctl(NULL, cmd);
	386
	387	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
3407ef52 JB	388	}
	389
	390	static int flakey_merge(struct dm_target ti, struct bvec_merge_data bvm,
	391	struct bio_vec *biovec, int max_size)
	392	{
	393	struct flakey_c *fc = ti->private;
	394	struct request_queue *q = bdev_get_queue(fc->dev->bdev);
	395
	396	if (!q->merge_bvec_fn)
	397	return max_size;
	398
	399	bvm->bi_bdev = fc->dev->bdev;
	400	bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
	401
	402	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
	403	}
	404
	405	static int flakey_iterate_devices(struct dm_target ti, iterate_devices_callout_fn fn, void data)
	406	{
	407	struct flakey_c *fc = ti->private;
	408
	409	return fn(ti, fc->dev, fc->start, ti->len, data);
	410	}
	411
	412	static struct target_type flakey_target = {
	413	.name = "flakey",
fd7c092e	414	.version = {1, 3, 1},
3407ef52 JB	415	.module = THIS_MODULE,
	416	.ctr = flakey_ctr,
	417	.dtr = flakey_dtr,
	418	.map = flakey_map,
a3998799	419	.end_io = flakey_end_io,
3407ef52 JB	420	.status = flakey_status,
	421	.ioctl = flakey_ioctl,
	422	.merge = flakey_merge,
	423	.iterate_devices = flakey_iterate_devices,
	424	};
	425
	426	static int __init dm_flakey_init(void)
	427	{
	428	int r = dm_register_target(&flakey_target);
	429
	430	if (r < 0)
	431	DMERR("register failed %d", r);
	432
	433	return r;
	434	}
	435
	436	static void __exit dm_flakey_exit(void)
	437	{
	438	dm_unregister_target(&flakey_target);
	439	}
	440
	441	/* Module hooks */
	442	module_init(dm_flakey_init);
	443	module_exit(dm_flakey_exit);
	444
	445	MODULE_DESCRIPTION(DM_NAME " flakey target");
	446	MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
	447	MODULE_LICENSE("GPL");