[linux-2.6-block.git] / drivers / md / dm-io.c

/*
 * Copyright (C) 2003 Sistina Software
 * Copyright (C) 2006 Red Hat GmbH
 *
 * 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>

struct dm_io_client {
	mempool_t *pool;
	struct bio_set *bios;
};

/* FIXME: can we shrink this ? */
struct io {
	unsigned long error;
	atomic_t count;
	struct task_struct *sleeper;
	struct dm_io_client *client;
	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 bios! (FIXME: must reduce this).
 */

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

/*
 * Create a client with mempool and bioset.
 */
struct dm_io_client *dm_io_client_create(unsigned num_pages)
{
	unsigned ios = pages_to_ios(num_pages);
	struct dm_io_client *client;

	client = kmalloc(sizeof(*client), GFP_KERNEL);
	if (!client)
		return ERR_PTR(-ENOMEM);

	client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
	if (!client->pool)
		goto bad;

	client->bios = bioset_create(16, 16);
	if (!client->bios)
		goto bad;

	return client;

   bad:
	if (client->pool)
		mempool_destroy(client->pool);
	kfree(client);
	return ERR_PTR(-ENOMEM);
}
EXPORT_SYMBOL(dm_io_client_create);

int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
{
	return mempool_resize(client->pool, pages_to_ios(num_pages),
			      GFP_KERNEL);
}
EXPORT_SYMBOL(dm_io_client_resize);

void dm_io_client_destroy(struct dm_io_client *client)
{
	mempool_destroy(client->pool);
	bioset_free(client->bios);
	kfree(client);
}
EXPORT_SYMBOL(dm_io_client_destroy);

/*-----------------------------------------------------------------
 * 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->client->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;
}

/*
 * Functions for getting the pages from a VMA.
 */
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)
{
	struct io *io = bio->bi_private;

	bio_free(bio, io->client->bios);
}

/*
 * Functions for getting the pages from kernel memory.
 */
static void km_get_page(struct dpages *dp, struct page **p, unsigned long *len,
			unsigned *offset)
{
	*p = virt_to_page(dp->context_ptr);
	*offset = dp->context_u;
	*len = PAGE_SIZE - dp->context_u;
}

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

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

/*-----------------------------------------------------------------
 * 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 = dm_sector_div_up(remaining,
					     (PAGE_SIZE >> SECTOR_SHIFT));
		num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev),
				      num_bvecs);
		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->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(struct dm_io_client *client, 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;
	io.client = client;

	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;

	if (error_bits)
		*error_bits = io.error;

	return io.error ? -EIO : 0;
}

static int async_io(struct dm_io_client *client, 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(client->pool, GFP_NOIO);
	io->error = 0;
	atomic_set(&io->count, 1); /* see dispatch_io() */
	io->sleeper = NULL;
	io->client = client;
	io->callback = fn;
	io->context = context;

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

static int dp_init(struct dm_io_request *io_req, struct dpages *dp)
{
	/* Set up dpages based on memory type */
	switch (io_req->mem.type) {
	case DM_IO_PAGE_LIST:
		list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
		break;

	case DM_IO_BVEC:
		bvec_dp_init(dp, io_req->mem.ptr.bvec);
		break;

	case DM_IO_VMA:
		vm_dp_init(dp, io_req->mem.ptr.vma);
		break;

	case DM_IO_KMEM:
		km_dp_init(dp, io_req->mem.ptr.addr);
		break;

	default:
		return -EINVAL;
	}

	return 0;
}

/*
 * New collapsed (a)synchronous interface
 */
int dm_io(struct dm_io_request *io_req, unsigned num_regions,
	  struct io_region *where, unsigned long *sync_error_bits)
{
	int r;
	struct dpages dp;

	r = dp_init(io_req, &dp);
	if (r)
		return r;

	if (!io_req->notify.fn)
		return sync_io(io_req->client, num_regions, where,
			       io_req->bi_rw, &dp, sync_error_bits);

	return async_io(io_req->client, num_regions, where, io_req->bi_rw,
			&dp, io_req->notify.fn, io_req->notify.context);
}
EXPORT_SYMBOL(dm_io);
Commit	Line	Data
1da177e4 LT	1	/*
1da177e4 LT	2	* Copyright (C) 2003 Sistina Software
891ce207	3	* Copyright (C) 2006 Red Hat GmbH
1da177e4 LT	4	*
	5	* This file is released under the GPL.
	6	*/
	7
	8	#include "dm-io.h"
	9
	10	#include <linux/bio.h>
	11	#include <linux/mempool.h>
	12	#include <linux/module.h>
	13	#include <linux/sched.h>
	14	#include <linux/slab.h>
	15
891ce207 HM	16	struct dm_io_client {
	17	mempool_t *pool;
	18	struct bio_set *bios;
	19	};
	20
1da177e4 LT	21	/* FIXME: can we shrink this ? */
	22	struct io {
	23	unsigned long error;
	24	atomic_t count;
	25	struct task_struct *sleeper;
891ce207	26	struct dm_io_client *client;
1da177e4 LT	27	io_notify_fn callback;
	28	void *context;
	29	};
	30
	31	/*
	32	* io contexts are only dynamically allocated for asynchronous
	33	* io. Since async io is likely to be the majority of io we'll
891ce207	34	* have the same number of io contexts as bios! (FIXME: must reduce this).
1da177e4	35	*/
891ce207	36
1da177e4 LT	37	static unsigned int pages_to_ios(unsigned int pages)
	38	{
	39	return 4 * pages; /* too many ? */
	40	}
	41
c8b03afe HM	42	/*
	43	* Create a client with mempool and bioset.
	44	*/
	45	struct dm_io_client *dm_io_client_create(unsigned num_pages)
	46	{
	47	unsigned ios = pages_to_ios(num_pages);
	48	struct dm_io_client *client;
	49
	50	client = kmalloc(sizeof(*client), GFP_KERNEL);
	51	if (!client)
	52	return ERR_PTR(-ENOMEM);
	53
	54	client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
	55	if (!client->pool)
	56	goto bad;
	57
	58	client->bios = bioset_create(16, 16);
	59	if (!client->bios)
	60	goto bad;
	61
	62	return client;
	63
	64	bad:
	65	if (client->pool)
	66	mempool_destroy(client->pool);
	67	kfree(client);
	68	return ERR_PTR(-ENOMEM);
	69	}
	70	EXPORT_SYMBOL(dm_io_client_create);
	71
	72	int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
	73	{
	74	return mempool_resize(client->pool, pages_to_ios(num_pages),
	75	GFP_KERNEL);
	76	}
	77	EXPORT_SYMBOL(dm_io_client_resize);
	78
	79	void dm_io_client_destroy(struct dm_io_client *client)
	80	{
	81	mempool_destroy(client->pool);
	82	bioset_free(client->bios);
	83	kfree(client);
	84	}
	85	EXPORT_SYMBOL(dm_io_client_destroy);
	86
1da177e4 LT	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
bf17ce3a	121	mempool_free(io, io->client->pool);
1da177e4 LT	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
c8b03afe HM	220	/*
	221	* Functions for getting the pages from a VMA.
	222	*/
1da177e4 LT	223	static void vm_get_page(struct dpages *dp,
	224	struct page *p, unsigned long len, unsigned *offset)
	225	{
	226	*p = vmalloc_to_page(dp->context_ptr);
	227	*offset = dp->context_u;
	228	*len = PAGE_SIZE - dp->context_u;
	229	}
	230
	231	static void vm_next_page(struct dpages *dp)
	232	{
	233	dp->context_ptr += PAGE_SIZE - dp->context_u;
	234	dp->context_u = 0;
	235	}
	236
	237	static void vm_dp_init(struct dpages dp, void data)
	238	{
	239	dp->get_page = vm_get_page;
	240	dp->next_page = vm_next_page;
	241	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	242	dp->context_ptr = data;
	243	}
	244
3676347a PO	245	static void dm_bio_destructor(struct bio *bio)
3676347a PO	246	{
891ce207 HM	247	struct io *io = bio->bi_private;
891ce207 HM	248
bf17ce3a	249	bio_free(bio, io->client->bios);
3676347a PO	250	}
3676347a PO	251
c8b03afe HM	252	/*
	253	* Functions for getting the pages from kernel memory.
	254	*/
	255	static void km_get_page(struct dpages dp, struct page p, unsigned long len,
	256	unsigned *offset)
	257	{
	258	*p = virt_to_page(dp->context_ptr);
	259	*offset = dp->context_u;
	260	*len = PAGE_SIZE - dp->context_u;
	261	}
	262
	263	static void km_next_page(struct dpages *dp)
	264	{
	265	dp->context_ptr += PAGE_SIZE - dp->context_u;
	266	dp->context_u = 0;
	267	}
	268
	269	static void km_dp_init(struct dpages dp, void data)
	270	{
	271	dp->get_page = km_get_page;
	272	dp->next_page = km_next_page;
	273	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	274	dp->context_ptr = data;
	275	}
	276
1da177e4 LT	277	/*-----------------------------------------------------------------
	278	* IO routines that accept a list of pages.
	279	---------------------------------------------------------------/
	280	static void do_region(int rw, unsigned int region, struct io_region *where,
	281	struct dpages dp, struct io io)
	282	{
	283	struct bio *bio;
	284	struct page *page;
	285	unsigned long len;
	286	unsigned offset;
	287	unsigned num_bvecs;
	288	sector_t remaining = where->count;
	289
	290	while (remaining) {
	291	/*
f00b16ad HM	292	* Allocate a suitably sized-bio: we add an extra
	293	* bvec for bio_get/set_region() and decrement bi_max_vecs
	294	* to hide it from bio_add_page().
1da177e4	295	*/
596f138e JN	296	num_bvecs = dm_sector_div_up(remaining,
	297	(PAGE_SIZE >> SECTOR_SHIFT));
	298	num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev),
	299	num_bvecs);
bf17ce3a	300	bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
1da177e4 LT	301	bio->bi_sector = where->sector + (where->count - remaining);
	302	bio->bi_bdev = where->bdev;
	303	bio->bi_end_io = endio;
	304	bio->bi_private = io;
3676347a	305	bio->bi_destructor = dm_bio_destructor;
f00b16ad	306	bio->bi_max_vecs--;
1da177e4 LT	307	bio_set_region(bio, region);
	308
	309	/*
	310	* Try and add as many pages as possible.
	311	*/
	312	while (remaining) {
	313	dp->get_page(dp, &page, &len, &offset);
	314	len = min(len, to_bytes(remaining));
	315	if (!bio_add_page(bio, page, len, offset))
	316	break;
	317
	318	offset = 0;
	319	remaining -= to_sector(len);
	320	dp->next_page(dp);
	321	}
	322
	323	atomic_inc(&io->count);
	324	submit_bio(rw, bio);
	325	}
	326	}
	327
	328	static void dispatch_io(int rw, unsigned int num_regions,
	329	struct io_region where, struct dpages dp,
	330	struct io *io, int sync)
	331	{
	332	int i;
	333	struct dpages old_pages = *dp;
	334
	335	if (sync)
	336	rw \|= (1 << BIO_RW_SYNC);
	337
	338	/*
	339	* For multiple regions we need to be careful to rewind
	340	* the dp object for each call to do_region.
	341	*/
	342	for (i = 0; i < num_regions; i++) {
	343	*dp = old_pages;
	344	if (where[i].count)
	345	do_region(rw, i, where + i, dp, io);
	346	}
	347
	348	/*
f00b16ad	349	* Drop the extra reference that we were holding to avoid
1da177e4 LT	350	* the io being completed too early.
	351	*/
	352	dec_count(io, 0, 0);
	353	}
	354
891ce207 HM	355	static int sync_io(struct dm_io_client *client, unsigned int num_regions,
	356	struct io_region where, int rw, struct dpages dp,
	357	unsigned long *error_bits)
1da177e4 LT	358	{
	359	struct io io;
	360
	361	if (num_regions > 1 && rw != WRITE) {
	362	WARN_ON(1);
	363	return -EIO;
	364	}
	365
	366	io.error = 0;
	367	atomic_set(&io.count, 1); /* see dispatch_io() */
	368	io.sleeper = current;
891ce207	369	io.client = client;
1da177e4 LT	370
	371	dispatch_io(rw, num_regions, where, dp, &io, 1);
	372
	373	while (1) {
	374	set_current_state(TASK_UNINTERRUPTIBLE);
	375
	376	if (!atomic_read(&io.count) \|\| signal_pending(current))
	377	break;
	378
	379	io_schedule();
	380	}
	381	set_current_state(TASK_RUNNING);
	382
	383	if (atomic_read(&io.count))
	384	return -EINTR;
	385
891ce207 HM	386	if (error_bits)
	387	*error_bits = io.error;
	388
1da177e4 LT	389	return io.error ? -EIO : 0;
	390	}
	391
891ce207 HM	392	static int async_io(struct dm_io_client *client, unsigned int num_regions,
	393	struct io_region where, int rw, struct dpages dp,
	394	io_notify_fn fn, void *context)
1da177e4 LT	395	{
	396	struct io *io;
	397
	398	if (num_regions > 1 && rw != WRITE) {
	399	WARN_ON(1);
	400	fn(1, context);
	401	return -EIO;
	402	}
	403
bf17ce3a	404	io = mempool_alloc(client->pool, GFP_NOIO);
1da177e4 LT	405	io->error = 0;
	406	atomic_set(&io->count, 1); /* see dispatch_io() */
	407	io->sleeper = NULL;
891ce207	408	io->client = client;
1da177e4 LT	409	io->callback = fn;
	410	io->context = context;
	411
	412	dispatch_io(rw, num_regions, where, dp, io, 0);
	413	return 0;
	414	}
	415
c8b03afe HM	416	static int dp_init(struct dm_io_request io_req, struct dpages dp)
	417	{
	418	/* Set up dpages based on memory type */
	419	switch (io_req->mem.type) {
	420	case DM_IO_PAGE_LIST:
	421	list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
	422	break;
	423
	424	case DM_IO_BVEC:
	425	bvec_dp_init(dp, io_req->mem.ptr.bvec);
	426	break;
	427
	428	case DM_IO_VMA:
	429	vm_dp_init(dp, io_req->mem.ptr.vma);
	430	break;
	431
	432	case DM_IO_KMEM:
	433	km_dp_init(dp, io_req->mem.ptr.addr);
	434	break;
	435
	436	default:
	437	return -EINVAL;
	438	}
	439
	440	return 0;
	441	}
	442
	443	/*
	444	* New collapsed (a)synchronous interface
	445	*/
	446	int dm_io(struct dm_io_request *io_req, unsigned num_regions,
	447	struct io_region where, unsigned long sync_error_bits)
	448	{
	449	int r;
	450	struct dpages dp;
	451
	452	r = dp_init(io_req, &dp);
	453	if (r)
	454	return r;
	455
	456	if (!io_req->notify.fn)
	457	return sync_io(io_req->client, num_regions, where,
	458	io_req->bi_rw, &dp, sync_error_bits);
	459
	460	return async_io(io_req->client, num_regions, where, io_req->bi_rw,
	461	&dp, io_req->notify.fn, io_req->notify.context);
	462	}
	463	EXPORT_SYMBOL(dm_io);