[net-next-2.6.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>

static struct bio_set *_bios;

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 _num_ios;
static mempool_t *_io_pool;

/*
 * Temporary functions to allow old and new interfaces to co-exist.
 */
static struct bio_set *bios(struct dm_io_client *client)
{
	return client ? client->bios : _bios;
}

static mempool_t *io_pool(struct dm_io_client *client)
{
	return client ? client->pool : _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));
}

/*
 * 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_pool(io->client));
			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, bios(io->client));
}

/*
 * 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 = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
		bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, bios(io->client));
		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(io_pool(client), 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;
}

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(NULL, 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(NULL, 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(NULL, 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(NULL, 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(NULL, 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(NULL, num_regions, where, rw, &dp, fn, context);
}

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);

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	/*
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
	16	static struct bio_set *_bios;
	17
891ce207 HM	18	struct dm_io_client {
	19	mempool_t *pool;
	20	struct bio_set *bios;
	21	};
	22
1da177e4 LT	23	/* FIXME: can we shrink this ? */
	24	struct io {
	25	unsigned long error;
	26	atomic_t count;
	27	struct task_struct *sleeper;
891ce207	28	struct dm_io_client *client;
1da177e4 LT	29	io_notify_fn callback;
	30	void *context;
	31	};
	32
	33	/*
	34	* io contexts are only dynamically allocated for asynchronous
	35	* io. Since async io is likely to be the majority of io we'll
891ce207	36	* have the same number of io contexts as bios! (FIXME: must reduce this).
1da177e4 LT	37	*/
	38	static unsigned _num_ios;
	39	static mempool_t *_io_pool;
	40
891ce207 HM	41	/*
	42	* Temporary functions to allow old and new interfaces to co-exist.
	43	*/
	44	static struct bio_set bios(struct dm_io_client client)
	45	{
	46	return client ? client->bios : _bios;
	47	}
	48
	49	static mempool_t io_pool(struct dm_io_client client)
	50	{
	51	return client ? client->pool : _io_pool;
	52	}
	53
1da177e4 LT	54	static unsigned int pages_to_ios(unsigned int pages)
	55	{
	56	return 4 * pages; /* too many ? */
	57	}
	58
	59	static int resize_pool(unsigned int new_ios)
	60	{
	61	int r = 0;
	62
	63	if (_io_pool) {
	64	if (new_ios == 0) {
	65	/* free off the pool */
	66	mempool_destroy(_io_pool);
	67	_io_pool = NULL;
	68	bioset_free(_bios);
	69
	70	} else {
	71	/* resize the pool */
	72	r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
	73	}
	74
	75	} else {
	76	/* create new pool */
0eaae62a MD	77	_io_pool = mempool_create_kmalloc_pool(new_ios,
0eaae62a MD	78	sizeof(struct io));
1da177e4 LT	79	if (!_io_pool)
	80	return -ENOMEM;
	81
5972511b	82	_bios = bioset_create(16, 16);
1da177e4 LT	83	if (!_bios) {
	84	mempool_destroy(_io_pool);
	85	_io_pool = NULL;
	86	return -ENOMEM;
	87	}
	88	}
	89
	90	if (!r)
	91	_num_ios = new_ios;
	92
	93	return r;
	94	}
	95
	96	int dm_io_get(unsigned int num_pages)
	97	{
	98	return resize_pool(_num_ios + pages_to_ios(num_pages));
	99	}
	100
	101	void dm_io_put(unsigned int num_pages)
	102	{
	103	resize_pool(_num_ios - pages_to_ios(num_pages));
	104	}
	105
c8b03afe HM	106	/*
	107	* Create a client with mempool and bioset.
	108	*/
	109	struct dm_io_client *dm_io_client_create(unsigned num_pages)
	110	{
	111	unsigned ios = pages_to_ios(num_pages);
	112	struct dm_io_client *client;
	113
	114	client = kmalloc(sizeof(*client), GFP_KERNEL);
	115	if (!client)
	116	return ERR_PTR(-ENOMEM);
	117
	118	client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
	119	if (!client->pool)
	120	goto bad;
	121
	122	client->bios = bioset_create(16, 16);
	123	if (!client->bios)
	124	goto bad;
	125
	126	return client;
	127
	128	bad:
	129	if (client->pool)
	130	mempool_destroy(client->pool);
	131	kfree(client);
	132	return ERR_PTR(-ENOMEM);
	133	}
	134	EXPORT_SYMBOL(dm_io_client_create);
	135
	136	int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
	137	{
	138	return mempool_resize(client->pool, pages_to_ios(num_pages),
	139	GFP_KERNEL);
	140	}
	141	EXPORT_SYMBOL(dm_io_client_resize);
	142
	143	void dm_io_client_destroy(struct dm_io_client *client)
	144	{
	145	mempool_destroy(client->pool);
	146	bioset_free(client->bios);
	147	kfree(client);
	148	}
	149	EXPORT_SYMBOL(dm_io_client_destroy);
	150
1da177e4 LT	151	/*-----------------------------------------------------------------
	152	* We need to keep track of which region a bio is doing io for.
	153	* In order to save a memory allocation we store this the last
	154	* bvec which we know is unused (blech).
	155	* XXX This is ugly and can OOPS with some configs... find another way.
	156	---------------------------------------------------------------/
	157	static inline void bio_set_region(struct bio *bio, unsigned region)
	158	{
f00b16ad	159	bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
1da177e4 LT	160	}
	161
	162	static inline unsigned bio_get_region(struct bio *bio)
	163	{
f00b16ad	164	return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
1da177e4 LT	165	}
	166
	167	/*-----------------------------------------------------------------
	168	* We need an io object to keep track of the number of bios that
	169	* have been dispatched for a particular io.
	170	---------------------------------------------------------------/
	171	static void dec_count(struct io *io, unsigned int region, int error)
	172	{
	173	if (error)
	174	set_bit(region, &io->error);
	175
	176	if (atomic_dec_and_test(&io->count)) {
	177	if (io->sleeper)
	178	wake_up_process(io->sleeper);
	179
	180	else {
	181	int r = io->error;
	182	io_notify_fn fn = io->callback;
	183	void *context = io->context;
	184
891ce207	185	mempool_free(io, io_pool(io->client));
1da177e4 LT	186	fn(r, context);
	187	}
	188	}
	189	}
	190
	191	static int endio(struct bio *bio, unsigned int done, int error)
	192	{
c897feb3 HM	193	struct io *io;
c897feb3 HM	194	unsigned region;
1da177e4 LT	195
	196	/* keep going until we've finished */
	197	if (bio->bi_size)
	198	return 1;
	199
	200	if (error && bio_data_dir(bio) == READ)
	201	zero_fill_bio(bio);
	202
c897feb3 HM	203	/*
	204	* The bio destructor in bio_put() may use the io object.
	205	*/
	206	io = bio->bi_private;
	207	region = bio_get_region(bio);
	208
f00b16ad	209	bio->bi_max_vecs++;
1da177e4 LT	210	bio_put(bio);
1da177e4 LT	211
c897feb3 HM	212	dec_count(io, region, error);
c897feb3 HM	213
1da177e4 LT	214	return 0;
	215	}
	216
	217	/*-----------------------------------------------------------------
	218	* These little objects provide an abstraction for getting a new
	219	* destination page for io.
	220	---------------------------------------------------------------/
	221	struct dpages {
	222	void (get_page)(struct dpages dp,
	223	struct page *p, unsigned long len, unsigned *offset);
	224	void (next_page)(struct dpages dp);
	225
	226	unsigned context_u;
	227	void *context_ptr;
	228	};
	229
	230	/*
	231	* Functions for getting the pages from a list.
	232	*/
	233	static void list_get_page(struct dpages *dp,
	234	struct page *p, unsigned long len, unsigned *offset)
	235	{
	236	unsigned o = dp->context_u;
	237	struct page_list pl = (struct page_list ) dp->context_ptr;
	238
	239	*p = pl->page;
	240	*len = PAGE_SIZE - o;
	241	*offset = o;
	242	}
	243
	244	static void list_next_page(struct dpages *dp)
	245	{
	246	struct page_list pl = (struct page_list ) dp->context_ptr;
	247	dp->context_ptr = pl->next;
	248	dp->context_u = 0;
	249	}
	250
	251	static void list_dp_init(struct dpages dp, struct page_list pl, unsigned offset)
	252	{
	253	dp->get_page = list_get_page;
	254	dp->next_page = list_next_page;
	255	dp->context_u = offset;
	256	dp->context_ptr = pl;
	257	}
	258
	259	/*
	260	* Functions for getting the pages from a bvec.
	261	*/
	262	static void bvec_get_page(struct dpages *dp,
	263	struct page *p, unsigned long len, unsigned *offset)
	264	{
	265	struct bio_vec bvec = (struct bio_vec ) dp->context_ptr;
	266	*p = bvec->bv_page;
	267	*len = bvec->bv_len;
	268	*offset = bvec->bv_offset;
	269	}
	270
	271	static void bvec_next_page(struct dpages *dp)
	272	{
	273	struct bio_vec bvec = (struct bio_vec ) dp->context_ptr;
	274	dp->context_ptr = bvec + 1;
	275	}
	276
	277	static void bvec_dp_init(struct dpages dp, struct bio_vec bvec)
278	{
279	dp->get_page = bvec_get_page;
280	dp->next_page = bvec_next_page;
281	dp->context_ptr = bvec;
282	}
283
c8b03afe HM	284	/*
	285	* Functions for getting the pages from a VMA.
	286	*/
1da177e4 LT	287	static void vm_get_page(struct dpages *dp,
	288	struct page *p, unsigned long len, unsigned *offset)
	289	{
	290	*p = vmalloc_to_page(dp->context_ptr);
	291	*offset = dp->context_u;
	292	*len = PAGE_SIZE - dp->context_u;
	293	}
	294
	295	static void vm_next_page(struct dpages *dp)
	296	{
	297	dp->context_ptr += PAGE_SIZE - dp->context_u;
	298	dp->context_u = 0;
	299	}
	300
	301	static void vm_dp_init(struct dpages dp, void data)
	302	{
	303	dp->get_page = vm_get_page;
	304	dp->next_page = vm_next_page;
	305	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	306	dp->context_ptr = data;
	307	}
	308
3676347a PO	309	static void dm_bio_destructor(struct bio *bio)
3676347a PO	310	{
891ce207 HM	311	struct io *io = bio->bi_private;
	312
	313	bio_free(bio, bios(io->client));
3676347a PO	314	}
3676347a PO	315
c8b03afe HM	316	/*
	317	* Functions for getting the pages from kernel memory.
	318	*/
	319	static void km_get_page(struct dpages dp, struct page p, unsigned long len,
	320	unsigned *offset)
	321	{
	322	*p = virt_to_page(dp->context_ptr);
	323	*offset = dp->context_u;
	324	*len = PAGE_SIZE - dp->context_u;
	325	}
	326
	327	static void km_next_page(struct dpages *dp)
	328	{
	329	dp->context_ptr += PAGE_SIZE - dp->context_u;
	330	dp->context_u = 0;
	331	}
	332
	333	static void km_dp_init(struct dpages dp, void data)
	334	{
	335	dp->get_page = km_get_page;
	336	dp->next_page = km_next_page;
	337	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	338	dp->context_ptr = data;
	339	}
	340
1da177e4 LT	341	/*-----------------------------------------------------------------
	342	* IO routines that accept a list of pages.
	343	---------------------------------------------------------------/
	344	static void do_region(int rw, unsigned int region, struct io_region *where,
	345	struct dpages dp, struct io io)
	346	{
	347	struct bio *bio;
	348	struct page *page;
	349	unsigned long len;
	350	unsigned offset;
	351	unsigned num_bvecs;
	352	sector_t remaining = where->count;
	353
	354	while (remaining) {
	355	/*
f00b16ad HM	356	* Allocate a suitably sized-bio: we add an extra
	357	* bvec for bio_get/set_region() and decrement bi_max_vecs
	358	* to hide it from bio_add_page().
1da177e4	359	*/
f00b16ad	360	num_bvecs = (remaining / (PAGE_SIZE >> SECTOR_SHIFT)) + 2;
891ce207	361	bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, bios(io->client));
1da177e4 LT	362	bio->bi_sector = where->sector + (where->count - remaining);
	363	bio->bi_bdev = where->bdev;
	364	bio->bi_end_io = endio;
	365	bio->bi_private = io;
3676347a	366	bio->bi_destructor = dm_bio_destructor;
f00b16ad	367	bio->bi_max_vecs--;
1da177e4 LT	368	bio_set_region(bio, region);
	369
	370	/*
	371	* Try and add as many pages as possible.
	372	*/
	373	while (remaining) {
	374	dp->get_page(dp, &page, &len, &offset);
	375	len = min(len, to_bytes(remaining));
	376	if (!bio_add_page(bio, page, len, offset))
	377	break;
	378
	379	offset = 0;
	380	remaining -= to_sector(len);
	381	dp->next_page(dp);
	382	}
	383
	384	atomic_inc(&io->count);
	385	submit_bio(rw, bio);
	386	}
	387	}
	388
	389	static void dispatch_io(int rw, unsigned int num_regions,
	390	struct io_region where, struct dpages dp,
	391	struct io *io, int sync)
	392	{
	393	int i;
	394	struct dpages old_pages = *dp;
	395
	396	if (sync)
	397	rw \|= (1 << BIO_RW_SYNC);
	398
	399	/*
	400	* For multiple regions we need to be careful to rewind
	401	* the dp object for each call to do_region.
	402	*/
	403	for (i = 0; i < num_regions; i++) {
	404	*dp = old_pages;
	405	if (where[i].count)
	406	do_region(rw, i, where + i, dp, io);
	407	}
	408
	409	/*
f00b16ad	410	* Drop the extra reference that we were holding to avoid
1da177e4 LT	411	* the io being completed too early.
	412	*/
	413	dec_count(io, 0, 0);
	414	}
	415
891ce207 HM	416	static int sync_io(struct dm_io_client *client, unsigned int num_regions,
	417	struct io_region where, int rw, struct dpages dp,
	418	unsigned long *error_bits)
1da177e4 LT	419	{
	420	struct io io;
	421
	422	if (num_regions > 1 && rw != WRITE) {
	423	WARN_ON(1);
	424	return -EIO;
	425	}
	426
	427	io.error = 0;
	428	atomic_set(&io.count, 1); /* see dispatch_io() */
	429	io.sleeper = current;
891ce207	430	io.client = client;
1da177e4 LT	431
	432	dispatch_io(rw, num_regions, where, dp, &io, 1);
	433
	434	while (1) {
	435	set_current_state(TASK_UNINTERRUPTIBLE);
	436
	437	if (!atomic_read(&io.count) \|\| signal_pending(current))
	438	break;
	439
	440	io_schedule();
	441	}
	442	set_current_state(TASK_RUNNING);
	443
	444	if (atomic_read(&io.count))
	445	return -EINTR;
	446
891ce207 HM	447	if (error_bits)
	448	*error_bits = io.error;
	449
1da177e4 LT	450	return io.error ? -EIO : 0;
	451	}
	452
891ce207 HM	453	static int async_io(struct dm_io_client *client, unsigned int num_regions,
	454	struct io_region where, int rw, struct dpages dp,
	455	io_notify_fn fn, void *context)
1da177e4 LT	456	{
	457	struct io *io;
	458
	459	if (num_regions > 1 && rw != WRITE) {
	460	WARN_ON(1);
	461	fn(1, context);
	462	return -EIO;
	463	}
	464
891ce207	465	io = mempool_alloc(io_pool(client), GFP_NOIO);
1da177e4 LT	466	io->error = 0;
	467	atomic_set(&io->count, 1); /* see dispatch_io() */
	468	io->sleeper = NULL;
891ce207	469	io->client = client;
1da177e4 LT	470	io->callback = fn;
	471	io->context = context;
	472
	473	dispatch_io(rw, num_regions, where, dp, io, 0);
	474	return 0;
	475	}
	476
	477	int dm_io_sync(unsigned int num_regions, struct io_region *where, int rw,
	478	struct page_list *pl, unsigned int offset,
	479	unsigned long *error_bits)
	480	{
	481	struct dpages dp;
	482	list_dp_init(&dp, pl, offset);
891ce207	483	return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
1da177e4 LT	484	}
	485
	486	int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
	487	struct bio_vec bvec, unsigned long error_bits)
	488	{
	489	struct dpages dp;
	490	bvec_dp_init(&dp, bvec);
891ce207	491	return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
1da177e4 LT	492	}
	493
	494	int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
	495	void data, unsigned long error_bits)
	496	{
	497	struct dpages dp;
	498	vm_dp_init(&dp, data);
891ce207	499	return sync_io(NULL, num_regions, where, rw, &dp, error_bits);
1da177e4 LT	500	}
	501
	502	int dm_io_async(unsigned int num_regions, struct io_region *where, int rw,
	503	struct page_list *pl, unsigned int offset,
	504	io_notify_fn fn, void *context)
	505	{
	506	struct dpages dp;
	507	list_dp_init(&dp, pl, offset);
891ce207	508	return async_io(NULL, num_regions, where, rw, &dp, fn, context);
1da177e4 LT	509	}
	510
	511	int dm_io_async_bvec(unsigned int num_regions, struct io_region *where, int rw,
	512	struct bio_vec bvec, io_notify_fn fn, void context)
	513	{
	514	struct dpages dp;
	515	bvec_dp_init(&dp, bvec);
891ce207	516	return async_io(NULL, num_regions, where, rw, &dp, fn, context);
1da177e4 LT	517	}
	518
	519	int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
	520	void data, io_notify_fn fn, void context)
	521	{
	522	struct dpages dp;
	523	vm_dp_init(&dp, data);
891ce207	524	return async_io(NULL, num_regions, where, rw, &dp, fn, context);
1da177e4 LT	525	}
1da177e4 LT	526
c8b03afe HM	527	static int dp_init(struct dm_io_request io_req, struct dpages dp)
	528	{
	529	/* Set up dpages based on memory type */
	530	switch (io_req->mem.type) {
	531	case DM_IO_PAGE_LIST:
	532	list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
	533	break;
	534
	535	case DM_IO_BVEC:
	536	bvec_dp_init(dp, io_req->mem.ptr.bvec);
	537	break;
	538
	539	case DM_IO_VMA:
	540	vm_dp_init(dp, io_req->mem.ptr.vma);
	541	break;
	542
	543	case DM_IO_KMEM:
	544	km_dp_init(dp, io_req->mem.ptr.addr);
	545	break;
	546
	547	default:
	548	return -EINVAL;
	549	}
	550
	551	return 0;
	552	}
	553
	554	/*
	555	* New collapsed (a)synchronous interface
	556	*/
	557	int dm_io(struct dm_io_request *io_req, unsigned num_regions,
	558	struct io_region where, unsigned long sync_error_bits)
	559	{
	560	int r;
	561	struct dpages dp;
	562
	563	r = dp_init(io_req, &dp);
	564	if (r)
	565	return r;
	566
	567	if (!io_req->notify.fn)
	568	return sync_io(io_req->client, num_regions, where,
	569	io_req->bi_rw, &dp, sync_error_bits);
	570
	571	return async_io(io_req->client, num_regions, where, io_req->bi_rw,
	572	&dp, io_req->notify.fn, io_req->notify.context);
	573	}
	574	EXPORT_SYMBOL(dm_io);
	575
1da177e4 LT	576	EXPORT_SYMBOL(dm_io_get);
	577	EXPORT_SYMBOL(dm_io_put);
	578	EXPORT_SYMBOL(dm_io_sync);
	579	EXPORT_SYMBOL(dm_io_async);
	580	EXPORT_SYMBOL(dm_io_sync_bvec);
	581	EXPORT_SYMBOL(dm_io_async_bvec);
	582	EXPORT_SYMBOL(dm_io_sync_vm);
	583	EXPORT_SYMBOL(dm_io_async_vm);