424 lines
9.9 KiB
C
424 lines
9.9 KiB
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, 4);
|
|
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 - 1].bv_len = region;
|
|
}
|
|
|
|
static inline unsigned bio_get_region(struct bio *bio)
|
|
{
|
|
return bio->bi_io_vec[bio->bi_max_vecs - 1].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 = (struct io *) bio->bi_private;
|
|
|
|
/* keep going until we've finished */
|
|
if (bio->bi_size)
|
|
return 1;
|
|
|
|
if (error && bio_data_dir(bio) == READ)
|
|
zero_fill_bio(bio);
|
|
|
|
dec_count(io, bio_get_region(bio), error);
|
|
bio_put(bio);
|
|
|
|
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().
|
|
*/
|
|
num_bvecs = (remaining / (PAGE_SIZE >> 9)) + 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_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 refence 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);
|