7 files changed, 267 insertions, 161 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index da5f5f2..3e64023 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -30,7 +30,6 @@
 #include <linux/device-mapper.h>
 
 #define DM_MSG_PREFIX "crypt"
-#define MESG_STR(x) x, sizeof(x)
 
 /*
  * context holding the current state of a multi-part conversion
@@ -238,7 +237,7 @@ static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv,
 			      struct dm_crypt_request *dmreq)
 {
 	memset(iv, 0, cc->iv_size);
-	*(u32 *)iv = cpu_to_le32(dmreq->iv_sector & 0xffffffff);
+	*(__le32 *)iv = cpu_to_le32(dmreq->iv_sector & 0xffffffff);
 
 	return 0;
 }
@@ -247,7 +246,7 @@ static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
 				struct dm_crypt_request *dmreq)
 {
 	memset(iv, 0, cc->iv_size);
-	*(u64 *)iv = cpu_to_le64(dmreq->iv_sector);
+	*(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);
 
 	return 0;
 }
@@ -414,7 +413,7 @@ static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv,
 	struct crypto_cipher *essiv_tfm = this_crypt_config(cc)->iv_private;
 
 	memset(iv, 0, cc->iv_size);
-	*(u64 *)iv = cpu_to_le64(dmreq->iv_sector);
+	*(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);
 	crypto_cipher_encrypt_one(essiv_tfm, iv, iv);
 
 	return 0;
@@ -1577,11 +1576,17 @@ bad_mem:
 static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	struct crypt_config *cc;
-	unsigned int key_size;
+	unsigned int key_size, opt_params;
 	unsigned long long tmpll;
 	int ret;
+	struct dm_arg_set as;
+	const char *opt_string;
+
+	static struct dm_arg _args[] = {
+		{0, 1, "Invalid number of feature args"},
+	};
 
-	if (argc != 5) {
+	if (argc < 5) {
 		ti->error = "Not enough arguments";
 		return -EINVAL;
 	}
@@ -1650,6 +1655,30 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	}
 	cc->start = tmpll;
 
+	argv += 5;
+	argc -= 5;
+
+	/* Optional parameters */
+	if (argc) {
+		as.argc = argc;
+		as.argv = argv;
+
+		ret = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
+		if (ret)
+			goto bad;
+
+		opt_string = dm_shift_arg(&as);
+
+		if (opt_params == 1 && opt_string &&
+		    !strcasecmp(opt_string, "allow_discards"))
+			ti->num_discard_requests = 1;
+		else if (opt_params) {
+			ret = -EINVAL;
+			ti->error = "Invalid feature arguments";
+			goto bad;
+		}
+	}
+
 	ret = -ENOMEM;
 #if 1
 	cc->io_queue = create_singlethread_workqueue("kcryptd_io");
@@ -1691,9 +1720,16 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
 	struct dm_crypt_io *io;
 	struct crypt_config *cc;
 
-	if (bio->bi_rw & REQ_FLUSH) {
+	/*
+	 * If bio is REQ_FLUSH or REQ_DISCARD, just bypass crypt queues.
+	 * - for REQ_FLUSH device-mapper core ensures that no IO is in-flight
+	 * - for REQ_DISCARD caller must use flush if IO ordering matters
+	 */
+	if (unlikely(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))) {
 		cc = ti->private;
 		bio->bi_bdev = cc->dev->bdev;
+		if (bio_sectors(bio))
+			bio->bi_sector = cc->start + dm_target_offset(ti, bio->bi_sector);
 		return DM_MAPIO_REMAPPED;
 	}
 
@@ -1736,6 +1772,10 @@ static int crypt_status(struct dm_target *ti, status_type_t type,
 
 		DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
 				cc->dev->name, (unsigned long long)cc->start);
+
+		if (ti->num_discard_requests)
+			DMEMIT(" 1 allow_discards");
+
 		break;
 	}
 	return 0;
@@ -1779,12 +1819,12 @@ static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
 	if (argc < 2)
 		goto error;
 
-	if (!strnicmp(argv[0], MESG_STR("key"))) {
+	if (!strcasecmp(argv[0], "key")) {
 		if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
 			DMWARN("not suspended during key manipulation.");
 			return -EINVAL;
 		}
-		if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) {
+		if (argc == 3 && !strcasecmp(argv[1], "set")) {
 			ret = crypt_set_key(cc, argv[2]);
 			if (ret)
 				return ret;
@@ -1792,7 +1832,7 @@ static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
 				ret = cc->iv_gen_ops->init(cc);
 			return ret;
 		}
-		if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) {
+		if (argc == 2 && !strcasecmp(argv[1], "wipe")) {
 			if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
 				ret = cc->iv_gen_ops->wipe(cc);
 				if (ret)
@@ -1832,7 +1872,7 @@ static int crypt_iterate_devices(struct dm_target *ti,
 
 static struct target_type crypt_target = {
 	.name   = "crypt",
-	.version = {1, 10, 0},
+	.version = {1, 11, 0},
 	.module = THIS_MODULE,
 	.ctr    = crypt_ctr,
 	.dtr    = crypt_dtr,
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 948e3f4..5f06fb6 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -197,15 +197,21 @@ EXPORT_SYMBOL(dm_dirty_log_destroy);
 #define MIRROR_DISK_VERSION 2
 #define LOG_OFFSET 2
 
-struct log_header {
-	uint32_t magic;
+struct log_header_disk {
+	__le32 magic;
 
 	/*
 	 * Simple, incrementing version. no backward
 	 * compatibility.
 	 */
+	__le32 version;
+	__le64 nr_regions;
+} __packed;
+
+struct log_header_core {
+	uint32_t magic;
 	uint32_t version;
-	sector_t nr_regions;
+	uint64_t nr_regions;
 };
 
 struct log_c {
@@ -239,10 +245,10 @@ struct log_c {
 	int log_dev_failed;
 	int log_dev_flush_failed;
 	struct dm_dev *log_dev;
-	struct log_header header;
+	struct log_header_core header;
 
 	struct dm_io_region header_location;
-	struct log_header *disk_header;
+	struct log_header_disk *disk_header;
 };
 
 /*
@@ -271,14 +277,14 @@ static inline void log_clear_bit(struct log_c *l,
 /*----------------------------------------------------------------
  * Header IO
  *--------------------------------------------------------------*/
-static void header_to_disk(struct log_header *core, struct log_header *disk)
+static void header_to_disk(struct log_header_core *core, struct log_header_disk *disk)
 {
 	disk->magic = cpu_to_le32(core->magic);
 	disk->version = cpu_to_le32(core->version);
 	disk->nr_regions = cpu_to_le64(core->nr_regions);
 }
 
-static void header_from_disk(struct log_header *core, struct log_header *disk)
+static void header_from_disk(struct log_header_core *core, struct log_header_disk *disk)
 {
 	core->magic = le32_to_cpu(disk->magic);
 	core->version = le32_to_cpu(disk->version);
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 70373bf..d13c431 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -22,7 +22,6 @@
 #include <asm/atomic.h>
 
 #define DM_MSG_PREFIX "multipath"
-#define MESG_STR(x) x, sizeof(x)
 #define DM_PG_INIT_DELAY_MSECS 2000
 #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1)
 
@@ -505,80 +504,29 @@ static void trigger_event(struct work_struct *work)
  *      <#paths> <#per-path selector args>
  *         [<path> [<arg>]* ]+ ]+
  *---------------------------------------------------------------*/
-struct param {
-	unsigned min;
-	unsigned max;
-	char *error;
-};
-
-static int read_param(struct param *param, char *str, unsigned *v, char **error)
-{
-	if (!str ||
-	    (sscanf(str, "%u", v) != 1) ||
-	    (*v < param->min) ||
-	    (*v > param->max)) {
-		*error = param->error;
-		return -EINVAL;
-	}
-
-	return 0;
-}
-
-struct arg_set {
-	unsigned argc;
-	char **argv;
-};
-
-static char *shift(struct arg_set *as)
-{
-	char *r;
-
-	if (as->argc) {
-		as->argc--;
-		r = *as->argv;
-		as->argv++;
-		return r;
-	}
-
-	return NULL;
-}
-
-static void consume(struct arg_set *as, unsigned n)
-{
-	BUG_ON (as->argc < n);
-	as->argc -= n;
-	as->argv += n;
-}
-
-static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
+static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
 			       struct dm_target *ti)
 {
 	int r;
 	struct path_selector_type *pst;
 	unsigned ps_argc;
 
-	static struct param _params[] = {
+	static struct dm_arg _args[] = {
 		{0, 1024, "invalid number of path selector args"},
 	};
 
-	pst = dm_get_path_selector(shift(as));
+	pst = dm_get_path_selector(dm_shift_arg(as));
 	if (!pst) {
 		ti->error = "unknown path selector type";
 		return -EINVAL;
 	}
 
-	r = read_param(_params, shift(as), &ps_argc, &ti->error);
+	r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
 	if (r) {
 		dm_put_path_selector(pst);
 		return -EINVAL;
 	}
 
-	if (ps_argc > as->argc) {
-		dm_put_path_selector(pst);
-		ti->error = "not enough arguments for path selector";
-		return -EINVAL;
-	}
-
 	r = pst->create(&pg->ps, ps_argc, as->argv);
 	if (r) {
 		dm_put_path_selector(pst);
@@ -587,12 +535,12 @@ static int parse_path_selector(struct arg_set *as, struct priority_group *pg,
 	}
 
 	pg->ps.type = pst;
-	consume(as, ps_argc);
+	dm_consume_args(as, ps_argc);
 
 	return 0;
 }
 
-static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
+static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
 			       struct dm_target *ti)
 {
 	int r;
@@ -609,7 +557,7 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 	if (!p)
 		return ERR_PTR(-ENOMEM);
 
-	r = dm_get_device(ti, shift(as), dm_table_get_mode(ti->table),
+	r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
 			  &p->path.dev);
 	if (r) {
 		ti->error = "error getting device";
@@ -660,16 +608,16 @@ static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps,
 	return ERR_PTR(r);
 }
 
-static struct priority_group *parse_priority_group(struct arg_set *as,
+static struct priority_group *parse_priority_group(struct dm_arg_set *as,
 						   struct multipath *m)
 {
-	static struct param _params[] = {
+	static struct dm_arg _args[] = {
 		{1, 1024, "invalid number of paths"},
 		{0, 1024, "invalid number of selector args"}
 	};
 
 	int r;
-	unsigned i, nr_selector_args, nr_params;
+	unsigned i, nr_selector_args, nr_args;
 	struct priority_group *pg;
 	struct dm_target *ti = m->ti;
 
@@ -693,26 +641,26 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
 	/*
 	 * read the paths
 	 */
-	r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error);
+	r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
 	if (r)
 		goto bad;
 
-	r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error);
+	r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
 	if (r)
 		goto bad;
 
-	nr_params = 1 + nr_selector_args;
+	nr_args = 1 + nr_selector_args;
 	for (i = 0; i < pg->nr_pgpaths; i++) {
 		struct pgpath *pgpath;
-		struct arg_set path_args;
+		struct dm_arg_set path_args;
 
-		if (as->argc < nr_params) {
+		if (as->argc < nr_args) {
 			ti->error = "not enough path parameters";
 			r = -EINVAL;
 			goto bad;
 		}
 
-		path_args.argc = nr_params;
+		path_args.argc = nr_args;
 		path_args.argv = as->argv;
 
 		pgpath = parse_path(&path_args, &pg->ps, ti);
@@ -723,7 +671,7 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
 
 		pgpath->pg = pg;
 		list_add_tail(&pgpath->list, &pg->pgpaths);
-		consume(as, nr_params);
+		dm_consume_args(as, nr_args);
 	}
 
 	return pg;
@@ -733,28 +681,23 @@ static struct priority_group *parse_priority_group(struct arg_set *as,
 	return ERR_PTR(r);
 }
 
-static int parse_hw_handler(struct arg_set *as, struct multipath *m)
+static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
 {
 	unsigned hw_argc;
 	int ret;
 	struct dm_target *ti = m->ti;
 
-	static struct param _params[] = {
+	static struct dm_arg _args[] = {
 		{0, 1024, "invalid number of hardware handler args"},
 	};
 
-	if (read_param(_params, shift(as), &hw_argc, &ti->error))
+	if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
 		return -EINVAL;
 
 	if (!hw_argc)
 		return 0;
 
-	if (hw_argc > as->argc) {
-		ti->error = "not enough arguments for hardware handler";
-		return -EINVAL;
-	}
-
-	m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL);
+	m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
 	request_module("scsi_dh_%s", m->hw_handler_name);
 	if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
 		ti->error = "unknown hardware handler type";
@@ -778,7 +721,7 @@ static int parse_hw_handler(struct arg_set *as, struct multipath *m)
 		for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
 			j = sprintf(p, "%s", as->argv[i]);
 	}
-	consume(as, hw_argc - 1);
+	dm_consume_args(as, hw_argc - 1);
 
 	return 0;
 fail:
@@ -787,52 +730,45 @@ fail:
 	return ret;
 }
 
-static int parse_features(struct arg_set *as, struct multipath *m)
+static int parse_features(struct dm_arg_set *as, struct multipath *m)
 {
 	int r;
 	unsigned argc;
 	struct dm_target *ti = m->ti;
-	const char *param_name;
+	const char *arg_name;
 
-	static struct param _params[] = {
+	static struct dm_arg _args[] = {
 		{0, 5, "invalid number of feature args"},
 		{1, 50, "pg_init_retries must be between 1 and 50"},
 		{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
 	};
 
-	r = read_param(_params, shift(as), &argc, &ti->error);
+	r = dm_read_arg_group(_args, as, &argc, &ti->error);
 	if (r)
 		return -EINVAL;
 
 	if (!argc)
 		return 0;
 
-	if (argc > as->argc) {
-		ti->error = "not enough arguments for features";
-		return -EINVAL;
-	}
-
 	do {
-		param_name = shift(as);
+		arg_name = dm_shift_arg(as);
 		argc--;
 
-		if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) {
+		if (!strcasecmp(arg_name, "queue_if_no_path")) {
 			r = queue_if_no_path(m, 1, 0);
 			continue;
 		}
 
-		if (!strnicmp(param_name, MESG_STR("pg_init_retries")) &&
+		if (!strcasecmp(arg_name, "pg_init_retries") &&
 		    (argc >= 1)) {
-			r = read_param(_params + 1, shift(as),
-				       &m->pg_init_retries, &ti->error);
+			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
 			argc--;
 			continue;
 		}
 
-		if (!strnicmp(param_name, MESG_STR("pg_init_delay_msecs")) &&
+		if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
 		    (argc >= 1)) {
-			r = read_param(_params + 2, shift(as),
-				       &m->pg_init_delay_msecs, &ti->error);
+			r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
 			argc--;
 			continue;
 		}
@@ -847,15 +783,15 @@ static int parse_features(struct arg_set *as, struct multipath *m)
 static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 			 char **argv)
 {
-	/* target parameters */
-	static struct param _params[] = {
+	/* target arguments */
+	static struct dm_arg _args[] = {
 		{0, 1024, "invalid number of priority groups"},
 		{0, 1024, "invalid initial priority group number"},
 	};
 
 	int r;
 	struct multipath *m;
-	struct arg_set as;
+	struct dm_arg_set as;
 	unsigned pg_count = 0;
 	unsigned next_pg_num;
 
@@ -876,11 +812,11 @@ static int multipath_ctr(struct dm_target *ti, unsigned int argc,
 	if (r)
 		goto bad;
 
-	r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error);
+	r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
 	if (r)
 		goto bad;
 
-	r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error);
+	r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
 	if (r)
 		goto bad;
 
@@ -1510,10 +1446,10 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 	}
 
 	if (argc == 1) {
-		if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) {
+		if (!strcasecmp(argv[0], "queue_if_no_path")) {
 			r = queue_if_no_path(m, 1, 0);
 			goto out;
-		} else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) {
+		} else if (!strcasecmp(argv[0], "fail_if_no_path")) {
 			r = queue_if_no_path(m, 0, 0);
 			goto out;
 		}
@@ -1524,18 +1460,18 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
 		goto out;
 	}
 
-	if (!strnicmp(argv[0], MESG_STR("disable_group"))) {
+	if (!strcasecmp(argv[0], "disable_group")) {
 		r = bypass_pg_num(m, argv[1], 1);
 		goto out;
-	} else if (!strnicmp(argv[0], MESG_STR("enable_group"))) {
+	} else if (!strcasecmp(argv[0], "enable_group")) {
 		r = bypass_pg_num(m, argv[1], 0);
 		goto out;
-	} else if (!strnicmp(argv[0], MESG_STR("switch_group"))) {
+	} else if (!strcasecmp(argv[0], "switch_group")) {
 		r = switch_pg_num(m, argv[1]);
 		goto out;
-	} else if (!strnicmp(argv[0], MESG_STR("reinstate_path")))
+	} else if (!strcasecmp(argv[0], "reinstate_path"))
 		action = reinstate_path;
-	else if (!strnicmp(argv[0], MESG_STR("fail_path")))
+	else if (!strcasecmp(argv[0], "fail_path"))
 		action = fail_path;
 	else {
 		DMWARN("Unrecognised multipath message received.");
diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index e4ecadf..39becbe 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -58,25 +58,30 @@
 #define NUM_SNAPSHOT_HDR_CHUNKS 1
 
 struct disk_header {
-	uint32_t magic;
+	__le32 magic;
 
 	/*
 	 * Is this snapshot valid.  There is no way of recovering
 	 * an invalid snapshot.
 	 */
-	uint32_t valid;
+	__le32 valid;
 
 	/*
 	 * Simple, incrementing version. no backward
 	 * compatibility.
 	 */
-	uint32_t version;
+	__le32 version;
 
 	/* In sectors */
-	uint32_t chunk_size;
-};
+	__le32 chunk_size;
+} __packed;
 
 struct disk_exception {
+	__le64 old_chunk;
+	__le64 new_chunk;
+} __packed;
+
+struct core_exception {
 	uint64_t old_chunk;
 	uint64_t new_chunk;
 };
@@ -396,32 +401,32 @@ static struct disk_exception *get_exception(struct pstore *ps, uint32_t index)
 }
 
 static void read_exception(struct pstore *ps,
-			   uint32_t index, struct disk_exception *result)
+			   uint32_t index, struct core_exception *result)
 {
-	struct disk_exception *e = get_exception(ps, index);
+	struct disk_exception *de = get_exception(ps, index);
 
 	/* copy it */
-	result->old_chunk = le64_to_cpu(e->old_chunk);
-	result->new_chunk = le64_to_cpu(e->new_chunk);
+	result->old_chunk = le64_to_cpu(de->old_chunk);
+	result->new_chunk = le64_to_cpu(de->new_chunk);
 }
 
 static void write_exception(struct pstore *ps,
-			    uint32_t index, struct disk_exception *de)
+			    uint32_t index, struct core_exception *e)
 {
-	struct disk_exception *e = get_exception(ps, index);
+	struct disk_exception *de = get_exception(ps, index);
 
 	/* copy it */
-	e->old_chunk = cpu_to_le64(de->old_chunk);
-	e->new_chunk = cpu_to_le64(de->new_chunk);
+	de->old_chunk = cpu_to_le64(e->old_chunk);
+	de->new_chunk = cpu_to_le64(e->new_chunk);
 }
 
 static void clear_exception(struct pstore *ps, uint32_t index)
 {
-	struct disk_exception *e = get_exception(ps, index);
+	struct disk_exception *de = get_exception(ps, index);
 
 	/* clear it */
-	e->old_chunk = 0;
-	e->new_chunk = 0;
+	de->old_chunk = 0;
+	de->new_chunk = 0;
 }
 
 /*
@@ -437,13 +442,13 @@ static int insert_exceptions(struct pstore *ps,
 {
 	int r;
 	unsigned int i;
-	struct disk_exception de;
+	struct core_exception e;
 
 	/* presume the area is full */
 	*full = 1;
 
 	for (i = 0; i < ps->exceptions_per_area; i++) {
-		read_exception(ps, i, &de);
+		read_exception(ps, i, &e);
 
 		/*
 		 * If the new_chunk is pointing at the start of
@@ -451,7 +456,7 @@ static int insert_exceptions(struct pstore *ps,
 		 * is we know that we've hit the end of the
 		 * exceptions.  Therefore the area is not full.
 		 */
-		if (de.new_chunk == 0LL) {
+		if (e.new_chunk == 0LL) {
 			ps->current_committed = i;
 			*full = 0;
 			break;
@@ -460,13 +465,13 @@ static int insert_exceptions(struct pstore *ps,
 		/*
 		 * Keep track of the start of the free chunks.
 		 */
-		if (ps->next_free <= de.new_chunk)
-			ps->next_free = de.new_chunk + 1;
+		if (ps->next_free <= e.new_chunk)
+			ps->next_free = e.new_chunk + 1;
 
 		/*
 		 * Otherwise we add the exception to the snapshot.
 		 */
-		r = callback(callback_context, de.old_chunk, de.new_chunk);
+		r = callback(callback_context, e.old_chunk, e.new_chunk);
 		if (r)
 			return r;
 	}
@@ -641,12 +646,12 @@ static void persistent_commit_exception(struct dm_exception_store *store,
 {
 	unsigned int i;
 	struct pstore *ps = get_info(store);
-	struct disk_exception de;
+	struct core_exception ce;
 	struct commit_callback *cb;
 
-	de.old_chunk = e->old_chunk;
-	de.new_chunk = e->new_chunk;
-	write_exception(ps, ps->current_committed++, &de);
+	ce.old_chunk = e->old_chunk;
+	ce.new_chunk = e->new_chunk;
+	write_exception(ps, ps->current_committed++, &ce);
 
 	/*
 	 * Add the callback to the back of the array.  This code
@@ -701,7 +706,7 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
 				    chunk_t *last_new_chunk)
 {
 	struct pstore *ps = get_info(store);
-	struct disk_exception de;
+	struct core_exception ce;
 	int nr_consecutive;
 	int r;
 
@@ -722,9 +727,9 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
 		ps->current_committed = ps->exceptions_per_area;
 	}
 
-	read_exception(ps, ps->current_committed - 1, &de);
-	*last_old_chunk = de.old_chunk;
-	*last_new_chunk = de.new_chunk;
+	read_exception(ps, ps->current_committed - 1, &ce);
+	*last_old_chunk = ce.old_chunk;
+	*last_new_chunk = ce.new_chunk;
 
 	/*
 	 * Find number of consecutive chunks within the current area,
@@ -733,9 +738,9 @@ static int persistent_prepare_merge(struct dm_exception_store *store,
 	for (nr_consecutive = 1; nr_consecutive < ps->current_committed;
 	     nr_consecutive++) {
 		read_exception(ps, ps->current_committed - 1 - nr_consecutive,
-			       &de);
-		if (de.old_chunk != *last_old_chunk - nr_consecutive ||
-		    de.new_chunk != *last_new_chunk - nr_consecutive)
+			       &ce);
+		if (ce.old_chunk != *last_old_chunk - nr_consecutive ||
+		    ce.new_chunk != *last_new_chunk - nr_consecutive)
 			break;
 	}
 
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index ebdae6e..92cd686 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -539,8 +539,7 @@ int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 	 * If not we'll force DM to use PAGE_SIZE or
 	 * smaller I/O, just to be safe.
 	 */
-
-	if (q->merge_bvec_fn && !ti->type->merge)
+	if (dm_queue_merge_is_compulsory(q) && !ti->type->merge)
 		blk_limits_max_hw_sectors(limits,
 					  (unsigned int) (PAGE_SIZE >> 9));
 	return 0;
@@ -802,6 +801,63 @@ int dm_table_add_target(struct dm_table *t, const char *type,
 	return r;
 }
 
+/*
+ * Target argument parsing helpers.
+ */
+static int validate_next_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
+			     unsigned *value, char **error, unsigned grouped)
+{
+	const char *arg_str = dm_shift_arg(arg_set);
+
+	if (!arg_str ||
+	    (sscanf(arg_str, "%u", value) != 1) ||
+	    (*value < arg->min) ||
+	    (*value > arg->max) ||
+	    (grouped && arg_set->argc < *value)) {
+		*error = arg->error;
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int dm_read_arg(struct dm_arg *arg, struct dm_arg_set *arg_set,
+		unsigned *value, char **error)
+{
+	return validate_next_arg(arg, arg_set, value, error, 0);
+}
+EXPORT_SYMBOL(dm_read_arg);
+
+int dm_read_arg_group(struct dm_arg *arg, struct dm_arg_set *arg_set,
+		      unsigned *value, char **error)
+{
+	return validate_next_arg(arg, arg_set, value, error, 1);
+}
+EXPORT_SYMBOL(dm_read_arg_group);
+
+const char *dm_shift_arg(struct dm_arg_set *as)
+{
+	char *r;
+
+	if (as->argc) {
+		as->argc--;
+		r = *as->argv;
+		as->argv++;
+		return r;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(dm_shift_arg);
+
+void dm_consume_args(struct dm_arg_set *as, unsigned num_args)
+{
+	BUG_ON(as->argc < num_args);
+	as->argc -= num_args;
+	as->argv += num_args;
+}
+EXPORT_SYMBOL(dm_consume_args);
+
 static int dm_table_set_type(struct dm_table *t)
 {
 	unsigned i;
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 9f472d5..1eeef9c 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -111,6 +111,7 @@ EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
 #define DMF_FREEING 3
 #define DMF_DELETING 4
 #define DMF_NOFLUSH_SUSPENDING 5
+#define DMF_MERGE_IS_OPTIONAL 6
 
 /*
  * Work processed by per-device workqueue.
@@ -2018,6 +2019,59 @@ static void __set_size(struct mapped_device *md, sector_t size)
 }
 
 /*
+ * Return 1 if the queue has a compulsory merge_bvec_fn function.
+ *
+ * If this function returns 0, then the device is either a non-dm
+ * device without a merge_bvec_fn, or it is a dm device that is
+ * able to split any bios it receives that are too big.
+ */
+int dm_queue_merge_is_compulsory(struct request_queue *q)
+{
+	struct mapped_device *dev_md;
+
+	if (!q->merge_bvec_fn)
+		return 0;
+
+	if (q->make_request_fn == dm_request) {
+		dev_md = q->queuedata;
+		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
+			return 0;
+	}
+
+	return 1;
+}
+
+static int dm_device_merge_is_compulsory(struct dm_target *ti,
+					 struct dm_dev *dev, sector_t start,
+					 sector_t len, void *data)
+{
+	struct block_device *bdev = dev->bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return dm_queue_merge_is_compulsory(q);
+}
+
+/*
+ * Return 1 if it is acceptable to ignore merge_bvec_fn based
+ * on the properties of the underlying devices.
+ */
+static int dm_table_merge_is_optional(struct dm_table *table)
+{
+	unsigned i = 0;
+	struct dm_target *ti;
+
+	while (i < dm_table_get_num_targets(table)) {
+		ti = dm_table_get_target(table, i++);
+
+		if (ti->type->iterate_devices &&
+		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
+			return 0;
+	}
+
+	return 1;
+}
+
+/*
  * Returns old map, which caller must destroy.
  */
 static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
@@ -2027,6 +2081,7 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 	struct request_queue *q = md->queue;
 	sector_t size;
 	unsigned long flags;
+	int merge_is_optional;
 
 	size = dm_table_get_size(t);
 
@@ -2052,10 +2107,16 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 
 	__bind_mempools(md, t);
 
+	merge_is_optional = dm_table_merge_is_optional(t);
+
 	write_lock_irqsave(&md->map_lock, flags);
 	old_map = md->map;
 	md->map = t;
 	dm_table_set_restrictions(t, q, limits);
+	if (merge_is_optional)
+		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
+	else
+		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
 	write_unlock_irqrestore(&md->map_lock, flags);
 
 	return old_map;
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 1aaf167..6745dbd 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -66,6 +66,8 @@ int dm_table_alloc_md_mempools(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
 
+int dm_queue_merge_is_compulsory(struct request_queue *q);
+
 void dm_lock_md_type(struct mapped_device *md);
 void dm_unlock_md_type(struct mapped_device *md);
 void dm_set_md_type(struct mapped_device *md, unsigned type);