[net-next-2.6.git] / drivers / md / dm-io.c

/*
 * Copyright (C) 2003 Sistina Software
 *
 * This file is released under the GPL.
 */

#include "dm-io.h"

#include <linux/bio.h>
#include <linux/mempool.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>

static struct bio_set *_bios;

/* FIXME: can we shrink this ? */
struct io {
	unsigned long error;
	atomic_t count;
	struct task_struct *sleeper;
	io_notify_fn callback;
	void *context;
};

/*
 * io contexts are only dynamically allocated for asynchronous
 * io.  Since async io is likely to be the majority of io we'll
 * have the same number of io contexts as buffer heads ! (FIXME:
 * must reduce this).
 */
static unsigned _num_ios;
static mempool_t *_io_pool;

static unsigned int pages_to_ios(unsigned int pages)
{
	return 4 * pages;	/* too many ? */
}

static int resize_pool(unsigned int new_ios)
{
	int r = 0;

	if (_io_pool) {
		if (new_ios == 0) {
			/* free off the pool */
			mempool_destroy(_io_pool);
			_io_pool = NULL;
			bioset_free(_bios);

		} else {
			/* resize the pool */
			r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
		}

	} else {
		/* create new pool */
		_io_pool = mempool_create_kmalloc_pool(new_ios,
						       sizeof(struct io));
		if (!_io_pool)
			return -ENOMEM;

		_bios = bioset_create(16, 16);
		if (!_bios) {
			mempool_destroy(_io_pool);
			_io_pool = NULL;
			return -ENOMEM;
		}
	}

	if (!r)
		_num_ios = new_ios;

	return r;
}

int dm_io_get(unsigned int num_pages)
{
	return resize_pool(_num_ios + pages_to_ios(num_pages));
}

void dm_io_put(unsigned int num_pages)
{
	resize_pool(_num_ios - pages_to_ios(num_pages));
}

/*-----------------------------------------------------------------
 * We need to keep track of which region a bio is doing io for.
 * In order to save a memory allocation we store this the last
 * bvec which we know is unused (blech).
 * XXX This is ugly and can OOPS with some configs... find another way.
 *---------------------------------------------------------------*/
static inline void bio_set_region(struct bio *bio, unsigned region)
{
	bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
}

static inline unsigned bio_get_region(struct bio *bio)
{
	return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
}

/*-----------------------------------------------------------------
 * We need an io object to keep track of the number of bios that
 * have been dispatched for a particular io.
 *---------------------------------------------------------------*/
static void dec_count(struct io *io, unsigned int region, int error)
{
	if (error)
		set_bit(region, &io->error);

	if (atomic_dec_and_test(&io->count)) {
		if (io->sleeper)
			wake_up_process(io->sleeper);

		else {
			int r = io->error;
			io_notify_fn fn = io->callback;
			void *context = io->context;

			mempool_free(io, _io_pool);
			fn(r, context);
		}
	}
}

static int endio(struct bio *bio, unsigned int done, int error)
{
	struct io *io;
	unsigned region;

	/* keep going until we've finished */
	if (bio->bi_size)
		return 1;

	if (error && bio_data_dir(bio) == READ)
		zero_fill_bio(bio);

	/*
	 * The bio destructor in bio_put() may use the io object.
	 */
	io = bio->bi_private;
	region = bio_get_region(bio);

	bio->bi_max_vecs++;
	bio_put(bio);

	dec_count(io, region, error);

	return 0;
}

/*-----------------------------------------------------------------
 * These little objects provide an abstraction for getting a new
 * destination page for io.
 *---------------------------------------------------------------*/
struct dpages {
	void (*get_page)(struct dpages *dp,
			 struct page **p, unsigned long *len, unsigned *offset);
	void (*next_page)(struct dpages *dp);

	unsigned context_u;
	void *context_ptr;
};

/*
 * Functions for getting the pages from a list.
 */
static void list_get_page(struct dpages *dp,
		  struct page **p, unsigned long *len, unsigned *offset)
{
	unsigned o = dp->context_u;
	struct page_list *pl = (struct page_list *) dp->context_ptr;

	*p = pl->page;
	*len = PAGE_SIZE - o;
	*offset = o;
}

static void list_next_page(struct dpages *dp)
{
	struct page_list *pl = (struct page_list *) dp->context_ptr;
	dp->context_ptr = pl->next;
	dp->context_u = 0;
}

static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offset)
{
	dp->get_page = list_get_page;
	dp->next_page = list_next_page;
	dp->context_u = offset;
	dp->context_ptr = pl;
}

/*
 * Functions for getting the pages from a bvec.
 */
static void bvec_get_page(struct dpages *dp,
		  struct page **p, unsigned long *len, unsigned *offset)
{
	struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
	*p = bvec->bv_page;
	*len = bvec->bv_len;
	*offset = bvec->bv_offset;
}

static void bvec_next_page(struct dpages *dp)
{
	struct bio_vec *bvec = (struct bio_vec *) dp->context_ptr;
	dp->context_ptr = bvec + 1;
}

static void bvec_dp_init(struct dpages *dp, struct bio_vec *bvec)
{
	dp->get_page = bvec_get_page;
	dp->next_page = bvec_next_page;
	dp->context_ptr = bvec;
}

static void vm_get_page(struct dpages *dp,
		 struct page **p, unsigned long *len, unsigned *offset)
{
	*p = vmalloc_to_page(dp->context_ptr);
	*offset = dp->context_u;
	*len = PAGE_SIZE - dp->context_u;
}

static void vm_next_page(struct dpages *dp)
{
	dp->context_ptr += PAGE_SIZE - dp->context_u;
	dp->context_u = 0;
}

static void vm_dp_init(struct dpages *dp, void *data)
{
	dp->get_page = vm_get_page;
	dp->next_page = vm_next_page;
	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	dp->context_ptr = data;
}

static void dm_bio_destructor(struct bio *bio)
{
	bio_free(bio, _bios);
}

/*-----------------------------------------------------------------
 * IO routines that accept a list of pages.
 *---------------------------------------------------------------*/
static void do_region(int rw, unsigned int region, struct io_region *where,
		      struct dpages *dp, struct io *io)
{
	struct bio *bio;
	struct page *page;
	unsigned long len;
	unsigned offset;
	unsigned num_bvecs;
	sector_t remaining = where->count;

	while (remaining) {
		/*
		 * Allocate a suitably sized-bio: we add an extra
		 * bvec for bio_get/set_region() and decrement bi_max_vecs
		 * to hide it from bio_add_page().
		 */
		num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
		bio->bi_sector = where->sector + (where->count - remaining);
		bio->bi_bdev = where->bdev;
		bio->bi_end_io = endio;
		bio->bi_private = io;
		bio->bi_destructor = dm_bio_destructor;
		bio->bi_max_vecs--;
		bio_set_region(bio, region);

		/*
		 * Try and add as many pages as possible.
		 */
		while (remaining) {
			dp->get_page(dp, &page, &len, &offset);
			len = min(len, to_bytes(remaining));
			if (!bio_add_page(bio, page, len, offset))
				break;

			offset = 0;
			remaining -= to_sector(len);
			dp->next_page(dp);
		}

		atomic_inc(&io->count);
		submit_bio(rw, bio);
	}
}

static void dispatch_io(int rw, unsigned int num_regions,
			struct io_region *where, struct dpages *dp,
			struct io *io, int sync)
{
	int i;
	struct dpages old_pages = *dp;

	if (sync)
		rw |= (1 << BIO_RW_SYNC);

	/*
	 * For multiple regions we need to be careful to rewind
	 * the dp object for each call to do_region.
	 */
	for (i = 0; i < num_regions; i++) {
		*dp = old_pages;
		if (where[i].count)
			do_region(rw, i, where + i, dp, io);
	}

	/*
	 * Drop the extra reference that we were holding to avoid
	 * the io being completed too early.
	 */
	dec_count(io, 0, 0);
}

static int sync_io(unsigned int num_regions, struct io_region *where,
	    int rw, struct dpages *dp, unsigned long *error_bits)
{
	struct io io;

	if (num_regions > 1 && rw != WRITE) {
		WARN_ON(1);
		return -EIO;
	}

	io.error = 0;
	atomic_set(&io.count, 1); /* see dispatch_io() */
	io.sleeper = current;

	dispatch_io(rw, num_regions, where, dp, &io, 1);

	while (1) {
		set_current_state(TASK_UNINTERRUPTIBLE);

		if (!atomic_read(&io.count) || signal_pending(current))
			break;

		io_schedule();
	}
	set_current_state(TASK_RUNNING);

	if (atomic_read(&io.count))
		return -EINTR;

	*error_bits = io.error;
	return io.error ? -EIO : 0;
}

static int async_io(unsigned int num_regions, struct io_region *where, int rw,
	     struct dpages *dp, io_notify_fn fn, void *context)
{
	struct io *io;

	if (num_regions > 1 && rw != WRITE) {
		WARN_ON(1);
		fn(1, context);
		return -EIO;
	}

	io = mempool_alloc(_io_pool, GFP_NOIO);
	io->error = 0;
	atomic_set(&io->count, 1); /* see dispatch_io() */
	io->sleeper = NULL;
	io->callback = fn;
	io->context = context;

	dispatch_io(rw, num_regions, where, dp, io, 0);
	return 0;
}

int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
	       struct page_list *pl, unsigned int offset,
	       unsigned long *error_bits)
{
	struct dpages dp;
	list_dp_init(&dp, pl, offset);
	return sync_io(num_regions, where, rw, &dp, error_bits);
}

int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
		    struct bio_vec *bvec, unsigned long *error_bits)
{
	struct dpages dp;
	bvec_dp_init(&dp, bvec);
	return sync_io(num_regions, where, rw, &dp, error_bits);
}

int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
		  void *data, unsigned long *error_bits)
{
	struct dpages dp;
	vm_dp_init(&dp, data);
	return sync_io(num_regions, where, rw, &dp, error_bits);
}

int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
		struct page_list *pl, unsigned int offset,
		io_notify_fn fn, void *context)
{
	struct dpages dp;
	list_dp_init(&dp, pl, offset);
	return async_io(num_regions, where, rw, &dp, fn, context);
}

int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
		     struct bio_vec *bvec, io_notify_fn fn, void *context)
{
	struct dpages dp;
	bvec_dp_init(&dp, bvec);
	return async_io(num_regions, where, rw, &dp, fn, context);
}

int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
		   void *data, io_notify_fn fn, void *context)
{
	struct dpages dp;
	vm_dp_init(&dp, data);
	return async_io(num_regions, where, rw, &dp, fn, context);
}

EXPORT_SYMBOL(dm_io_get);
EXPORT_SYMBOL(dm_io_put);
EXPORT_SYMBOL(dm_io_sync);
EXPORT_SYMBOL(dm_io_async);
EXPORT_SYMBOL(dm_io_sync_bvec);
EXPORT_SYMBOL(dm_io_async_bvec);
EXPORT_SYMBOL(dm_io_sync_vm);
EXPORT_SYMBOL(dm_io_async_vm);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2003 Sistina Software
	3	*
	4	* This file is released under the GPL.
	5	*/
	6
	7	#include "dm-io.h"
	8
	9	#include <linux/bio.h>
	10	#include <linux/mempool.h>
	11	#include <linux/module.h>
	12	#include <linux/sched.h>
	13	#include <linux/slab.h>
	14
	15	static struct bio_set *_bios;
	16
	17	/* FIXME: can we shrink this ? */
	18	struct io {
	19	unsigned long error;
	20	atomic_t count;
	21	struct task_struct *sleeper;
	22	io_notify_fn callback;
	23	void *context;
	24	};
	25
	26	/*
	27	* io contexts are only dynamically allocated for asynchronous
	28	* io. Since async io is likely to be the majority of io we'll
	29	* have the same number of io contexts as buffer heads ! (FIXME:
	30	* must reduce this).
	31	*/
	32	static unsigned _num_ios;
	33	static mempool_t *_io_pool;
	34
1da177e4 LT	35	static unsigned int pages_to_ios(unsigned int pages)
	36	{
	37	return 4 * pages; /* too many ? */
	38	}
	39
	40	static int resize_pool(unsigned int new_ios)
	41	{
	42	int r = 0;
	43
	44	if (_io_pool) {
	45	if (new_ios == 0) {
	46	/* free off the pool */
	47	mempool_destroy(_io_pool);
	48	_io_pool = NULL;
	49	bioset_free(_bios);
	50
	51	} else {
	52	/* resize the pool */
	53	r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
	54	}
	55
	56	} else {
	57	/* create new pool */
0eaae62a MD	58	_io_pool = mempool_create_kmalloc_pool(new_ios,
0eaae62a MD	59	sizeof(struct io));
1da177e4 LT	60	if (!_io_pool)
	61	return -ENOMEM;
	62
5972511b	63	_bios = bioset_create(16, 16);
1da177e4 LT	64	if (!_bios) {
	65	mempool_destroy(_io_pool);
	66	_io_pool = NULL;
	67	return -ENOMEM;
	68	}
	69	}
	70
	71	if (!r)
	72	_num_ios = new_ios;
	73
	74	return r;
	75	}
	76
	77	int dm_io_get(unsigned int num_pages)
	78	{
	79	return resize_pool(_num_ios + pages_to_ios(num_pages));
	80	}
	81
	82	void dm_io_put(unsigned int num_pages)
	83	{
	84	resize_pool(_num_ios - pages_to_ios(num_pages));
	85	}
	86
	87	/*-----------------------------------------------------------------
	88	* We need to keep track of which region a bio is doing io for.
	89	* In order to save a memory allocation we store this the last
	90	* bvec which we know is unused (blech).
	91	* XXX This is ugly and can OOPS with some configs... find another way.
	92	---------------------------------------------------------------/
	93	static inline void bio_set_region(struct bio *bio, unsigned region)
	94	{
f00b16ad	95	bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
1da177e4 LT	96	}
	97
	98	static inline unsigned bio_get_region(struct bio *bio)
	99	{
f00b16ad	100	return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
1da177e4 LT	101	}
	102
	103	/*-----------------------------------------------------------------
	104	* We need an io object to keep track of the number of bios that
	105	* have been dispatched for a particular io.
	106	---------------------------------------------------------------/
	107	static void dec_count(struct io *io, unsigned int region, int error)
	108	{
	109	if (error)
	110	set_bit(region, &io->error);
	111
	112	if (atomic_dec_and_test(&io->count)) {
	113	if (io->sleeper)
	114	wake_up_process(io->sleeper);
	115
	116	else {
	117	int r = io->error;
	118	io_notify_fn fn = io->callback;
	119	void *context = io->context;
	120
	121	mempool_free(io, _io_pool);
	122	fn(r, context);
	123	}
	124	}
	125	}
	126
	127	static int endio(struct bio *bio, unsigned int done, int error)
	128	{
c897feb3 HM	129	struct io *io;
c897feb3 HM	130	unsigned region;
1da177e4 LT	131
	132	/* keep going until we've finished */
	133	if (bio->bi_size)
	134	return 1;
	135
	136	if (error && bio_data_dir(bio) == READ)
	137	zero_fill_bio(bio);
	138
c897feb3 HM	139	/*
	140	* The bio destructor in bio_put() may use the io object.
	141	*/
	142	io = bio->bi_private;
	143	region = bio_get_region(bio);
	144
f00b16ad	145	bio->bi_max_vecs++;
1da177e4 LT	146	bio_put(bio);
1da177e4 LT	147
c897feb3 HM	148	dec_count(io, region, error);
c897feb3 HM	149
1da177e4 LT	150	return 0;
	151	}
	152
	153	/*-----------------------------------------------------------------
	154	* These little objects provide an abstraction for getting a new
	155	* destination page for io.
	156	---------------------------------------------------------------/
	157	struct dpages {
	158	void (get_page)(struct dpages dp,
	159	struct page *p, unsigned long len, unsigned *offset);
	160	void (next_page)(struct dpages dp);
	161
	162	unsigned context_u;
	163	void *context_ptr;
	164	};
	165
	166	/*
	167	* Functions for getting the pages from a list.
	168	*/
	169	static void list_get_page(struct dpages *dp,
	170	struct page *p, unsigned long len, unsigned *offset)
	171	{
	172	unsigned o = dp->context_u;
	173	struct page_list pl = (struct page_list ) dp->context_ptr;
	174
	175	*p = pl->page;
	176	*len = PAGE_SIZE - o;
	177	*offset = o;
	178	}
	179
	180	static void list_next_page(struct dpages *dp)
	181	{
	182	struct page_list pl = (struct page_list ) dp->context_ptr;
	183	dp->context_ptr = pl->next;
	184	dp->context_u = 0;
	185	}
	186
	187	static void list_dp_init(struct dpages dp, struct page_list pl, unsigned offset)
	188	{
	189	dp->get_page = list_get_page;
	190	dp->next_page = list_next_page;
	191	dp->context_u = offset;
	192	dp->context_ptr = pl;
	193	}
	194
	195	/*
	196	* Functions for getting the pages from a bvec.
	197	*/
	198	static void bvec_get_page(struct dpages *dp,
	199	struct page *p, unsigned long len, unsigned *offset)
	200	{
	201	struct bio_vec bvec = (struct bio_vec ) dp->context_ptr;
	202	*p = bvec->bv_page;
	203	*len = bvec->bv_len;
	204	*offset = bvec->bv_offset;
	205	}
	206
	207	static void bvec_next_page(struct dpages *dp)
	208	{
	209	struct bio_vec bvec = (struct bio_vec ) dp->context_ptr;
	210	dp->context_ptr = bvec + 1;
	211	}
	212
	213	static void bvec_dp_init(struct dpages dp, struct bio_vec bvec)
214	{
215	dp->get_page = bvec_get_page;
216	dp->next_page = bvec_next_page;
217	dp->context_ptr = bvec;
218	}
219
220	static void vm_get_page(struct dpages *dp,
221	struct page *p, unsigned long len, unsigned *offset)
222	{
223	*p = vmalloc_to_page(dp->context_ptr);
224	*offset = dp->context_u;
225	*len = PAGE_SIZE - dp->context_u;
226	}
227
228	static void vm_next_page(struct dpages *dp)
229	{
230	dp->context_ptr += PAGE_SIZE - dp->context_u;
231	dp->context_u = 0;
232	}
233
234	static void vm_dp_init(struct dpages dp, void data)
235	{
236	dp->get_page = vm_get_page;
237	dp->next_page = vm_next_page;
238	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
239	dp->context_ptr = data;
240	}
241
3676347a PO	242	static void dm_bio_destructor(struct bio *bio)
	243	{
	244	bio_free(bio, _bios);
	245	}
	246
1da177e4 LT	247	/*-----------------------------------------------------------------
	248	* IO routines that accept a list of pages.
	249	---------------------------------------------------------------/
	250	static void do_region(int rw, unsigned int region, struct io_region *where,
	251	struct dpages dp, struct io io)
	252	{
	253	struct bio *bio;
	254	struct page *page;
	255	unsigned long len;
	256	unsigned offset;
	257	unsigned num_bvecs;
	258	sector_t remaining = where->count;
	259
	260	while (remaining) {
	261	/*
f00b16ad HM	262	* Allocate a suitably sized-bio: we add an extra
	263	* bvec for bio_get/set_region() and decrement bi_max_vecs
	264	* to hide it from bio_add_page().
1da177e4	265	*/
f00b16ad	266	num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
1da177e4 LT	267	bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, _bios);
	268	bio->bi_sector = where->sector + (where->count - remaining);
	269	bio->bi_bdev = where->bdev;
	270	bio->bi_end_io = endio;
	271	bio->bi_private = io;
3676347a	272	bio->bi_destructor = dm_bio_destructor;
f00b16ad	273	bio->bi_max_vecs--;
1da177e4 LT	274	bio_set_region(bio, region);
	275
	276	/*
	277	* Try and add as many pages as possible.
	278	*/
	279	while (remaining) {
	280	dp->get_page(dp, &page, &len, &offset);
	281	len = min(len, to_bytes(remaining));
	282	if (!bio_add_page(bio, page, len, offset))
	283	break;
	284
	285	offset = 0;
	286	remaining -= to_sector(len);
	287	dp->next_page(dp);
	288	}
	289
	290	atomic_inc(&io->count);
	291	submit_bio(rw, bio);
	292	}
	293	}
	294
	295	static void dispatch_io(int rw, unsigned int num_regions,
	296	struct io_region where, struct dpages dp,
	297	struct io *io, int sync)
	298	{
	299	int i;
	300	struct dpages old_pages = *dp;
	301
	302	if (sync)
	303	rw \|= (1 << BIO_RW_SYNC);
	304
	305	/*
	306	* For multiple regions we need to be careful to rewind
	307	* the dp object for each call to do_region.
	308	*/
	309	for (i = 0; i < num_regions; i++) {
	310	*dp = old_pages;
	311	if (where[i].count)
	312	do_region(rw, i, where + i, dp, io);
	313	}
	314
	315	/*
f00b16ad	316	* Drop the extra reference that we were holding to avoid
1da177e4 LT	317	* the io being completed too early.
	318	*/
	319	dec_count(io, 0, 0);
	320	}
	321
	322	static int sync_io(unsigned int num_regions, struct io_region *where,
	323	int rw, struct dpages dp, unsigned long error_bits)
	324	{
	325	struct io io;
	326
	327	if (num_regions > 1 && rw != WRITE) {
	328	WARN_ON(1);
	329	return -EIO;
	330	}
	331
	332	io.error = 0;
	333	atomic_set(&io.count, 1); /* see dispatch_io() */
	334	io.sleeper = current;
	335
	336	dispatch_io(rw, num_regions, where, dp, &io, 1);
	337
	338	while (1) {
	339	set_current_state(TASK_UNINTERRUPTIBLE);
	340
	341	if (!atomic_read(&io.count) \|\| signal_pending(current))
	342	break;
	343
	344	io_schedule();
	345	}
	346	set_current_state(TASK_RUNNING);
	347
	348	if (atomic_read(&io.count))
	349	return -EINTR;
	350
	351	*error_bits = io.error;
	352	return io.error ? -EIO : 0;
	353	}
	354
	355	static int async_io(unsigned int num_regions, struct io_region *where, int rw,
	356	struct dpages dp, io_notify_fn fn, void context)
	357	{
	358	struct io *io;
	359
	360	if (num_regions > 1 && rw != WRITE) {
	361	WARN_ON(1);
	362	fn(1, context);
	363	return -EIO;
	364	}
	365
	366	io = mempool_alloc(_io_pool, GFP_NOIO);
	367	io->error = 0;
	368	atomic_set(&io->count, 1); /* see dispatch_io() */
	369	io->sleeper = NULL;
	370	io->callback = fn;
	371	io->context = context;
	372
	373	dispatch_io(rw, num_regions, where, dp, io, 0);
	374	return 0;
	375	}
	376
	377	int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
	378	struct page_list *pl, unsigned int offset,
	379	unsigned long *error_bits)
	380	{
381	struct dpages dp;
382	list_dp_init(&dp, pl, offset);
383	return sync_io(num_regions, where, rw, &dp, error_bits);
384	}
385
386	int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
387	struct bio_vec bvec, unsigned long error_bits)
388	{
389	struct dpages dp;
390	bvec_dp_init(&dp, bvec);
391	return sync_io(num_regions, where, rw, &dp, error_bits);
392	}
393
394	int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
395	void data, unsigned long error_bits)
396	{
397	struct dpages dp;
398	vm_dp_init(&dp, data);
399	return sync_io(num_regions, where, rw, &dp, error_bits);
400	}
401
402	int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
403	struct page_list *pl, unsigned int offset,
404	io_notify_fn fn, void *context)
405	{
406	struct dpages dp;
407	list_dp_init(&dp, pl, offset);
408	return async_io(num_regions, where, rw, &dp, fn, context);
409	}
410
411	int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
412	struct bio_vec bvec, io_notify_fn fn, void context)
413	{
414	struct dpages dp;
415	bvec_dp_init(&dp, bvec);
416	return async_io(num_regions, where, rw, &dp, fn, context);
417	}
418
419	int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
420	void data, io_notify_fn fn, void context)
421	{
422	struct dpages dp;
423	vm_dp_init(&dp, data);
424	return async_io(num_regions, where, rw, &dp, fn, context);
425	}
426
427	EXPORT_SYMBOL(dm_io_get);
428	EXPORT_SYMBOL(dm_io_put);
429	EXPORT_SYMBOL(dm_io_sync);
430	EXPORT_SYMBOL(dm_io_async);
431	EXPORT_SYMBOL(dm_io_sync_bvec);
432	EXPORT_SYMBOL(dm_io_async_bvec);
433	EXPORT_SYMBOL(dm_io_sync_vm);
434	EXPORT_SYMBOL(dm_io_async_vm);