[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 <linux/device-mapper.h>

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

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

/* FIXME: can we shrink this ? */
struct io {
	unsigned long error_bits;
	unsigned long eopnotsupp_bits;
	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, 0);
	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_bits);
		if (error == -EOPNOTSUPP)
			set_bit(region, &io->eopnotsupp_bits);
	}

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

		else {
			unsigned long r = io->error_bits;
			io_notify_fn fn = io->callback;
			void *context = io->context;

			mempool_free(io, io->client->pool);
			fn(r, context);
		}
	}
}

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

	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);
}

/*-----------------------------------------------------------------
 * 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 region, struct dm_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);
		if (unlikely(num_bvecs > BIO_MAX_PAGES))
			num_bvecs = BIO_MAX_PAGES;
		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 dm_io_region *where, struct dpages *dp,
			struct io *io, int sync)
{
	int i;
	struct dpages old_pages = *dp;

	if (sync)
		rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);

	/*
	 * 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 dm_io_region *where, int rw, struct dpages *dp,
		   unsigned long *error_bits)
{
	struct io io;

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

retry:
	io.error_bits = 0;
	io.eopnotsupp_bits = 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))
			break;

		io_schedule();
	}
	set_current_state(TASK_RUNNING);

	if (io.eopnotsupp_bits && (rw & (1 << BIO_RW_BARRIER))) {
		rw &= ~(1 << BIO_RW_BARRIER);
		goto retry;
	}

	if (error_bits)
		*error_bits = io.error_bits;

	return io.error_bits ? -EIO : 0;
}

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

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

	io = mempool_alloc(client->pool, GFP_NOIO);
	io->error_bits = 0;
	io->eopnotsupp_bits = 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.
 *
 * If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
 * the queue with blk_unplug() some time later or set the BIO_RW_SYNC bit in
 * io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
 * the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
 */
int dm_io(struct dm_io_request *io_req, unsigned num_regions,
	  struct dm_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
586e80e6	8	#include <linux/device-mapper.h>
1da177e4 LT	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>
a765e20e	15	#include <linux/dm-io.h>
1da177e4	16
891ce207 HM	17	struct dm_io_client {
	18	mempool_t *pool;
	19	struct bio_set *bios;
	20	};
	21
1da177e4 LT	22	/* FIXME: can we shrink this ? */
1da177e4 LT	23	struct io {
e01fd7ee	24	unsigned long error_bits;
5af443a7	25	unsigned long eopnotsupp_bits;
1da177e4 LT	26	atomic_t count;
1da177e4 LT	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	37	*/
891ce207	38
1da177e4 LT	39	static unsigned int pages_to_ios(unsigned int pages)
	40	{
	41	return 4 * pages; /* too many ? */
	42	}
	43
c8b03afe HM	44	/*
	45	* Create a client with mempool and bioset.
	46	*/
	47	struct dm_io_client *dm_io_client_create(unsigned num_pages)
	48	{
	49	unsigned ios = pages_to_ios(num_pages);
	50	struct dm_io_client *client;
	51
	52	client = kmalloc(sizeof(*client), GFP_KERNEL);
	53	if (!client)
	54	return ERR_PTR(-ENOMEM);
	55
	56	client->pool = mempool_create_kmalloc_pool(ios, sizeof(struct io));
	57	if (!client->pool)
	58	goto bad;
	59
bb799ca0	60	client->bios = bioset_create(16, 0);
c8b03afe HM	61	if (!client->bios)
	62	goto bad;
	63
	64	return client;
	65
	66	bad:
	67	if (client->pool)
	68	mempool_destroy(client->pool);
	69	kfree(client);
	70	return ERR_PTR(-ENOMEM);
	71	}
	72	EXPORT_SYMBOL(dm_io_client_create);
	73
	74	int dm_io_client_resize(unsigned num_pages, struct dm_io_client *client)
	75	{
	76	return mempool_resize(client->pool, pages_to_ios(num_pages),
	77	GFP_KERNEL);
	78	}
	79	EXPORT_SYMBOL(dm_io_client_resize);
	80
	81	void dm_io_client_destroy(struct dm_io_client *client)
	82	{
	83	mempool_destroy(client->pool);
	84	bioset_free(client->bios);
	85	kfree(client);
	86	}
	87	EXPORT_SYMBOL(dm_io_client_destroy);
	88
1da177e4 LT	89	/*-----------------------------------------------------------------
	90	* We need to keep track of which region a bio is doing io for.
	91	* In order to save a memory allocation we store this the last
	92	* bvec which we know is unused (blech).
	93	* XXX This is ugly and can OOPS with some configs... find another way.
	94	---------------------------------------------------------------/
	95	static inline void bio_set_region(struct bio *bio, unsigned region)
	96	{
f00b16ad	97	bio->bi_io_vec[bio->bi_max_vecs].bv_len = region;
1da177e4 LT	98	}
	99
	100	static inline unsigned bio_get_region(struct bio *bio)
	101	{
f00b16ad	102	return bio->bi_io_vec[bio->bi_max_vecs].bv_len;
1da177e4 LT	103	}
	104
	105	/*-----------------------------------------------------------------
	106	* We need an io object to keep track of the number of bios that
	107	* have been dispatched for a particular io.
	108	---------------------------------------------------------------/
	109	static void dec_count(struct io *io, unsigned int region, int error)
	110	{
5af443a7	111	if (error) {
e01fd7ee	112	set_bit(region, &io->error_bits);
5af443a7 MP	113	if (error == -EOPNOTSUPP)
	114	set_bit(region, &io->eopnotsupp_bits);
	115	}
1da177e4 LT	116
	117	if (atomic_dec_and_test(&io->count)) {
	118	if (io->sleeper)
	119	wake_up_process(io->sleeper);
	120
	121	else {
e01fd7ee	122	unsigned long r = io->error_bits;
1da177e4 LT	123	io_notify_fn fn = io->callback;
	124	void *context = io->context;
	125
bf17ce3a	126	mempool_free(io, io->client->pool);
1da177e4 LT	127	fn(r, context);
	128	}
	129	}
	130	}
	131
6712ecf8	132	static void endio(struct bio *bio, int error)
1da177e4	133	{
c897feb3 HM	134	struct io *io;
c897feb3 HM	135	unsigned region;
1da177e4	136
1da177e4 LT	137	if (error && bio_data_dir(bio) == READ)
	138	zero_fill_bio(bio);
	139
c897feb3 HM	140	/*
	141	* The bio destructor in bio_put() may use the io object.
	142	*/
	143	io = bio->bi_private;
	144	region = bio_get_region(bio);
	145
f00b16ad	146	bio->bi_max_vecs++;
1da177e4 LT	147	bio_put(bio);
1da177e4 LT	148
c897feb3	149	dec_count(io, region, error);
1da177e4 LT	150	}
	151
	152	/*-----------------------------------------------------------------
	153	* These little objects provide an abstraction for getting a new
	154	* destination page for io.
	155	---------------------------------------------------------------/
	156	struct dpages {
	157	void (get_page)(struct dpages dp,
	158	struct page *p, unsigned long len, unsigned *offset);
	159	void (next_page)(struct dpages dp);
	160
	161	unsigned context_u;
	162	void *context_ptr;
	163	};
	164
	165	/*
	166	* Functions for getting the pages from a list.
	167	*/
	168	static void list_get_page(struct dpages *dp,
	169	struct page *p, unsigned long len, unsigned *offset)
	170	{
	171	unsigned o = dp->context_u;
	172	struct page_list pl = (struct page_list ) dp->context_ptr;
	173
	174	*p = pl->page;
	175	*len = PAGE_SIZE - o;
	176	*offset = o;
	177	}
	178
	179	static void list_next_page(struct dpages *dp)
	180	{
	181	struct page_list pl = (struct page_list ) dp->context_ptr;
	182	dp->context_ptr = pl->next;
	183	dp->context_u = 0;
	184	}
	185
	186	static void list_dp_init(struct dpages dp, struct page_list pl, unsigned offset)
	187	{
	188	dp->get_page = list_get_page;
	189	dp->next_page = list_next_page;
	190	dp->context_u = offset;
	191	dp->context_ptr = pl;
	192	}
	193
	194	/*
	195	* Functions for getting the pages from a bvec.
	196	*/
	197	static void bvec_get_page(struct dpages *dp,
	198	struct page *p, unsigned long len, unsigned *offset)
	199	{
	200	struct bio_vec bvec = (struct bio_vec ) dp->context_ptr;
	201	*p = bvec->bv_page;
	202	*len = bvec->bv_len;
	203	*offset = bvec->bv_offset;
	204	}
	205
	206	static void bvec_next_page(struct dpages *dp)
	207	{
	208	struct bio_vec bvec = (struct bio_vec ) dp->context_ptr;
	209	dp->context_ptr = bvec + 1;
	210	}
	211
	212	static void bvec_dp_init(struct dpages dp, struct bio_vec bvec)
	213	{
214	dp->get_page = bvec_get_page;
215	dp->next_page = bvec_next_page;
216	dp->context_ptr = bvec;
217	}
218
c8b03afe HM	219	/*
	220	* Functions for getting the pages from a VMA.
	221	*/
1da177e4 LT	222	static void vm_get_page(struct dpages *dp,
	223	struct page *p, unsigned long len, unsigned *offset)
	224	{
	225	*p = vmalloc_to_page(dp->context_ptr);
	226	*offset = dp->context_u;
	227	*len = PAGE_SIZE - dp->context_u;
	228	}
	229
	230	static void vm_next_page(struct dpages *dp)
	231	{
	232	dp->context_ptr += PAGE_SIZE - dp->context_u;
	233	dp->context_u = 0;
	234	}
	235
	236	static void vm_dp_init(struct dpages dp, void data)
	237	{
	238	dp->get_page = vm_get_page;
	239	dp->next_page = vm_next_page;
	240	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	241	dp->context_ptr = data;
	242	}
	243
3676347a PO	244	static void dm_bio_destructor(struct bio *bio)
3676347a PO	245	{
891ce207 HM	246	struct io *io = bio->bi_private;
891ce207 HM	247
bf17ce3a	248	bio_free(bio, io->client->bios);
3676347a PO	249	}
3676347a PO	250
c8b03afe HM	251	/*
	252	* Functions for getting the pages from kernel memory.
	253	*/
	254	static void km_get_page(struct dpages dp, struct page p, unsigned long len,
	255	unsigned *offset)
	256	{
	257	*p = virt_to_page(dp->context_ptr);
	258	*offset = dp->context_u;
	259	*len = PAGE_SIZE - dp->context_u;
	260	}
	261
	262	static void km_next_page(struct dpages *dp)
	263	{
	264	dp->context_ptr += PAGE_SIZE - dp->context_u;
	265	dp->context_u = 0;
	266	}
	267
	268	static void km_dp_init(struct dpages dp, void data)
	269	{
	270	dp->get_page = km_get_page;
	271	dp->next_page = km_next_page;
	272	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
	273	dp->context_ptr = data;
	274	}
	275
1da177e4 LT	276	/*-----------------------------------------------------------------
	277	* IO routines that accept a list of pages.
	278	---------------------------------------------------------------/
22a1ceb1	279	static void do_region(int rw, unsigned region, struct dm_io_region *where,
1da177e4 LT	280	struct dpages dp, struct io io)
	281	{
	282	struct bio *bio;
	283	struct page *page;
	284	unsigned long len;
	285	unsigned offset;
	286	unsigned num_bvecs;
	287	sector_t remaining = where->count;
	288
	289	while (remaining) {
	290	/*
f00b16ad HM	291	* Allocate a suitably sized-bio: we add an extra
	292	* bvec for bio_get/set_region() and decrement bi_max_vecs
	293	* to hide it from bio_add_page().
1da177e4	294	*/
596f138e JN	295	num_bvecs = dm_sector_div_up(remaining,
	296	(PAGE_SIZE >> SECTOR_SHIFT));
	297	num_bvecs = 1 + min_t(int, bio_get_nr_vecs(where->bdev),
	298	num_bvecs);
d659e6cc MP	299	if (unlikely(num_bvecs > BIO_MAX_PAGES))
d659e6cc MP	300	num_bvecs = BIO_MAX_PAGES;
bf17ce3a	301	bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
1da177e4 LT	302	bio->bi_sector = where->sector + (where->count - remaining);
	303	bio->bi_bdev = where->bdev;
	304	bio->bi_end_io = endio;
	305	bio->bi_private = io;
3676347a	306	bio->bi_destructor = dm_bio_destructor;
f00b16ad	307	bio->bi_max_vecs--;
1da177e4 LT	308	bio_set_region(bio, region);
	309
	310	/*
	311	* Try and add as many pages as possible.
	312	*/
	313	while (remaining) {
	314	dp->get_page(dp, &page, &len, &offset);
	315	len = min(len, to_bytes(remaining));
	316	if (!bio_add_page(bio, page, len, offset))
	317	break;
	318
	319	offset = 0;
	320	remaining -= to_sector(len);
	321	dp->next_page(dp);
	322	}
	323
	324	atomic_inc(&io->count);
	325	submit_bio(rw, bio);
	326	}
	327	}
	328
	329	static void dispatch_io(int rw, unsigned int num_regions,
22a1ceb1	330	struct dm_io_region where, struct dpages dp,
1da177e4 LT	331	struct io *io, int sync)
	332	{
	333	int i;
	334	struct dpages old_pages = *dp;
	335
	336	if (sync)
93dbb393	337	rw \|= (1 << BIO_RW_SYNCIO) \| (1 << BIO_RW_UNPLUG);
1da177e4 LT	338
	339	/*
	340	* For multiple regions we need to be careful to rewind
	341	* the dp object for each call to do_region.
	342	*/
	343	for (i = 0; i < num_regions; i++) {
	344	*dp = old_pages;
	345	if (where[i].count)
	346	do_region(rw, i, where + i, dp, io);
	347	}
	348
	349	/*
f00b16ad	350	* Drop the extra reference that we were holding to avoid
1da177e4 LT	351	* the io being completed too early.
	352	*/
	353	dec_count(io, 0, 0);
	354	}
	355
891ce207	356	static int sync_io(struct dm_io_client *client, unsigned int num_regions,
22a1ceb1	357	struct dm_io_region where, int rw, struct dpages dp,
891ce207	358	unsigned long *error_bits)
1da177e4 LT	359	{
	360	struct io io;
	361
7ff14a36	362	if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
1da177e4 LT	363	WARN_ON(1);
	364	return -EIO;
	365	}
	366
51aa3228	367	retry:
e01fd7ee	368	io.error_bits = 0;
5af443a7	369	io.eopnotsupp_bits = 0;
1da177e4 LT	370	atomic_set(&io.count, 1); /* see dispatch_io() */
1da177e4 LT	371	io.sleeper = current;
891ce207	372	io.client = client;
1da177e4 LT	373
	374	dispatch_io(rw, num_regions, where, dp, &io, 1);
	375
	376	while (1) {
	377	set_current_state(TASK_UNINTERRUPTIBLE);
	378
b64b6bf4	379	if (!atomic_read(&io.count))
1da177e4 LT	380	break;
	381
	382	io_schedule();
	383	}
	384	set_current_state(TASK_RUNNING);
	385
51aa3228 MP	386	if (io.eopnotsupp_bits && (rw & (1 << BIO_RW_BARRIER))) {
	387	rw &= ~(1 << BIO_RW_BARRIER);
	388	goto retry;
	389	}
	390
891ce207	391	if (error_bits)
e01fd7ee	392	*error_bits = io.error_bits;
891ce207	393
e01fd7ee	394	return io.error_bits ? -EIO : 0;
1da177e4 LT	395	}
1da177e4 LT	396
891ce207	397	static int async_io(struct dm_io_client *client, unsigned int num_regions,
22a1ceb1	398	struct dm_io_region where, int rw, struct dpages dp,
891ce207	399	io_notify_fn fn, void *context)
1da177e4 LT	400	{
	401	struct io *io;
	402
7ff14a36	403	if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
1da177e4 LT	404	WARN_ON(1);
	405	fn(1, context);
	406	return -EIO;
	407	}
	408
bf17ce3a	409	io = mempool_alloc(client->pool, GFP_NOIO);
e01fd7ee	410	io->error_bits = 0;
5af443a7	411	io->eopnotsupp_bits = 0;
1da177e4 LT	412	atomic_set(&io->count, 1); /* see dispatch_io() */
1da177e4 LT	413	io->sleeper = NULL;
891ce207	414	io->client = client;
1da177e4 LT	415	io->callback = fn;
	416	io->context = context;
	417
	418	dispatch_io(rw, num_regions, where, dp, io, 0);
	419	return 0;
	420	}
	421
c8b03afe HM	422	static int dp_init(struct dm_io_request io_req, struct dpages dp)
	423	{
	424	/* Set up dpages based on memory type */
	425	switch (io_req->mem.type) {
	426	case DM_IO_PAGE_LIST:
	427	list_dp_init(dp, io_req->mem.ptr.pl, io_req->mem.offset);
	428	break;
	429
	430	case DM_IO_BVEC:
	431	bvec_dp_init(dp, io_req->mem.ptr.bvec);
	432	break;
	433
	434	case DM_IO_VMA:
	435	vm_dp_init(dp, io_req->mem.ptr.vma);
	436	break;
	437
	438	case DM_IO_KMEM:
	439	km_dp_init(dp, io_req->mem.ptr.addr);
	440	break;
	441
	442	default:
	443	return -EINVAL;
	444	}
	445
	446	return 0;
	447	}
	448
	449	/*
7ff14a36 MP	450	* New collapsed (a)synchronous interface.
	451	*
	452	* If the IO is asynchronous (i.e. it has notify.fn), you must either unplug
	453	* the queue with blk_unplug() some time later or set the BIO_RW_SYNC bit in
	454	* io_req->bi_rw. If you fail to do one of these, the IO will be submitted to
	455	* the disk after q->unplug_delay, which defaults to 3ms in blk-settings.c.
c8b03afe HM	456	*/
c8b03afe HM	457	int dm_io(struct dm_io_request *io_req, unsigned num_regions,
22a1ceb1	458	struct dm_io_region where, unsigned long sync_error_bits)
c8b03afe HM	459	{
	460	int r;
	461	struct dpages dp;
	462
	463	r = dp_init(io_req, &dp);
	464	if (r)
	465	return r;
	466
	467	if (!io_req->notify.fn)
	468	return sync_io(io_req->client, num_regions, where,
	469	io_req->bi_rw, &dp, sync_error_bits);
	470
	471	return async_io(io_req->client, num_regions, where, io_req->bi_rw,
	472	&dp, io_req->notify.fn, io_req->notify.context);
	473	}
	474	EXPORT_SYMBOL(dm_io);