Commit b2ce210e authored by Alasdair G. Kergon's avatar Alasdair G. Kergon Committed by Linus Torvalds

[PATCH] dm-io: device-mapper i/o library for kcopyd

Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 78d601f9
......@@ -3,7 +3,7 @@
#
dm-mod-objs := dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
dm-ioctl.o
dm-ioctl.o dm-io.o
raid6-objs := raid6main.o raid6algos.o raid6recov.o raid6tables.o \
raid6int1.o raid6int2.o raid6int4.o \
raid6int8.o raid6int16.o raid6int32.o \
......
/*
* 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>
#define BIO_POOL_SIZE 256
/*-----------------------------------------------------------------
* Bio set, move this to bio.c
*---------------------------------------------------------------*/
#define BV_NAME_SIZE 16
struct biovec_pool {
int nr_vecs;
char name[BV_NAME_SIZE];
kmem_cache_t *slab;
mempool_t *pool;
atomic_t allocated; /* FIXME: debug */
};
#define BIOVEC_NR_POOLS 6
struct bio_set {
char name[BV_NAME_SIZE];
kmem_cache_t *bio_slab;
mempool_t *bio_pool;
struct biovec_pool pools[BIOVEC_NR_POOLS];
};
static void bio_set_exit(struct bio_set *bs)
{
unsigned i;
struct biovec_pool *bp;
if (bs->bio_pool)
mempool_destroy(bs->bio_pool);
if (bs->bio_slab)
kmem_cache_destroy(bs->bio_slab);
for (i = 0; i < BIOVEC_NR_POOLS; i++) {
bp = bs->pools + i;
if (bp->pool)
mempool_destroy(bp->pool);
if (bp->slab)
kmem_cache_destroy(bp->slab);
}
}
static void mk_name(char *str, size_t len, const char *prefix, unsigned count)
{
snprintf(str, len, "%s-%u", prefix, count);
}
static int bio_set_init(struct bio_set *bs, const char *slab_prefix,
unsigned pool_entries, unsigned scale)
{
/* FIXME: this must match bvec_index(), why not go the
* whole hog and have a pool per power of 2 ? */
static unsigned _vec_lengths[BIOVEC_NR_POOLS] = {
1, 4, 16, 64, 128, BIO_MAX_PAGES
};
unsigned i, size;
struct biovec_pool *bp;
/* zero the bs so we can tear down properly on error */
memset(bs, 0, sizeof(*bs));
/*
* Set up the bio pool.
*/
snprintf(bs->name, sizeof(bs->name), "%s-bio", slab_prefix);
bs->bio_slab = kmem_cache_create(bs->name, sizeof(struct bio), 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (!bs->bio_slab) {
DMWARN("can't init bio slab");
goto bad;
}
bs->bio_pool = mempool_create(pool_entries, mempool_alloc_slab,
mempool_free_slab, bs->bio_slab);
if (!bs->bio_pool) {
DMWARN("can't init bio pool");
goto bad;
}
/*
* Set up the biovec pools.
*/
for (i = 0; i < BIOVEC_NR_POOLS; i++) {
bp = bs->pools + i;
bp->nr_vecs = _vec_lengths[i];
atomic_set(&bp->allocated, 1); /* FIXME: debug */
size = bp->nr_vecs * sizeof(struct bio_vec);
mk_name(bp->name, sizeof(bp->name), slab_prefix, i);
bp->slab = kmem_cache_create(bp->name, size, 0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (!bp->slab) {
DMWARN("can't init biovec slab cache");
goto bad;
}
if (i >= scale)
pool_entries >>= 1;
bp->pool = mempool_create(pool_entries, mempool_alloc_slab,
mempool_free_slab, bp->slab);
if (!bp->pool) {
DMWARN("can't init biovec mempool");
goto bad;
}
}
return 0;
bad:
bio_set_exit(bs);
return -ENOMEM;
}
/* FIXME: blech */
static inline unsigned bvec_index(unsigned nr)
{
switch (nr) {
case 1: return 0;
case 2 ... 4: return 1;
case 5 ... 16: return 2;
case 17 ... 64: return 3;
case 65 ... 128:return 4;
case 129 ... BIO_MAX_PAGES: return 5;
}
BUG();
return 0;
}
static inline void bs_bio_init(struct bio *bio)
{
bio->bi_next = NULL;
bio->bi_flags = 1 << BIO_UPTODATE;
bio->bi_rw = 0;
bio->bi_vcnt = 0;
bio->bi_idx = 0;
bio->bi_phys_segments = 0;
bio->bi_hw_segments = 0;
bio->bi_size = 0;
bio->bi_max_vecs = 0;
bio->bi_end_io = NULL;
atomic_set(&bio->bi_cnt, 1);
bio->bi_private = NULL;
}
static unsigned _bio_count = 0;
struct bio *bio_set_alloc(struct bio_set *bs, int gfp_mask, int nr_iovecs)
{
struct biovec_pool *bp;
struct bio_vec *bv = NULL;
unsigned long idx;
struct bio *bio;
bio = mempool_alloc(bs->bio_pool, gfp_mask);
if (unlikely(!bio))
return NULL;
bio_init(bio);
if (likely(nr_iovecs)) {
idx = bvec_index(nr_iovecs);
bp = bs->pools + idx;
bv = mempool_alloc(bp->pool, gfp_mask);
if (!bv) {
mempool_free(bio, bs->bio_pool);
return NULL;
}
memset(bv, 0, bp->nr_vecs * sizeof(*bv));
bio->bi_flags |= idx << BIO_POOL_OFFSET;
bio->bi_max_vecs = bp->nr_vecs;
atomic_inc(&bp->allocated);
}
bio->bi_io_vec = bv;
return bio;
}
static void bio_set_free(struct bio_set *bs, struct bio *bio)
{
struct biovec_pool *bp = bs->pools + BIO_POOL_IDX(bio);
if (atomic_dec_and_test(&bp->allocated))
BUG();
mempool_free(bio->bi_io_vec, bp->pool);
mempool_free(bio, bs->bio_pool);
}
/*-----------------------------------------------------------------
* dm-io proper
*---------------------------------------------------------------*/
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 void *alloc_io(int gfp_mask, void *pool_data)
{
return kmalloc(sizeof(struct io), gfp_mask);
}
static void free_io(void *element, void *pool_data)
{
kfree(element);
}
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;
bio_set_exit(&_bios);
} else {
/* resize the pool */
r = mempool_resize(_io_pool, new_ios, GFP_KERNEL);
}
} else {
/* create new pool */
_io_pool = mempool_create(new_ios, alloc_io, free_io, NULL);
if (!_io_pool)
r = -ENOMEM;
r = bio_set_init(&_bios, "dm-io", 512, 1);
if (r) {
mempool_destroy(_io_pool);
_io_pool = NULL;
}
}
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).
*---------------------------------------------------------------*/
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);
}
}
}
/* FIXME Move this to bio.h? */
static void zero_fill_bio(struct bio *bio)
{
unsigned long flags;
struct bio_vec *bv;
int i;
bio_for_each_segment(bv, bio, i) {
char *data = bvec_kmap_irq(bv, &flags);
memset(data, 0, bv->bv_len);
flush_dcache_page(bv->bv_page);
bvec_kunmap_irq(data, &flags);
}
}
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;
}
static void bio_dtr(struct bio *bio)
{
_bio_count--;
bio_set_free(&_bios, bio);
}
/*-----------------------------------------------------------------
* 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;
}
/*-----------------------------------------------------------------
* 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_count++;
bio = bio_set_alloc(&_bios, GFP_NOIO, num_bvecs);
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 = bio_dtr;
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;
BUG_ON(num_regions > 1 && rw != WRITE);
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 = 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);
/*
* Copyright (C) 2003 Sistina Software
*
* This file is released under the GPL.
*/
#ifndef _DM_IO_H
#define _DM_IO_H
#include "dm.h"
/* FIXME make this configurable */
#define DM_MAX_IO_REGIONS 8
struct io_region {
struct block_device *bdev;
sector_t sector;
sector_t count;
};
struct page_list {
struct page_list *next;
struct page *page;
};
/*
* 'error' is a bitset, with each bit indicating whether an error
* occurred doing io to the corresponding region.
*/
typedef void (*io_notify_fn)(unsigned long error, void *context);
/*
* Before anyone uses the IO interface they should call
* dm_io_get(), specifying roughly how many pages they are
* expecting to perform io on concurrently.
*
* This function may block.
*/
int dm_io_get(unsigned int num_pages);
void dm_io_put(unsigned int num_pages);
/*
* Synchronous IO.
*
* Please ensure that the rw flag in the next two functions is
* either READ or WRITE, ie. we don't take READA. Any
* regions with a zero count field will be ignored.
*/
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);
int dm_io_sync_bvec(unsigned int num_regions, struct io_region *where, int rw,
struct bio_vec *bvec, unsigned long *error_bits);
int dm_io_sync_vm(unsigned int num_regions, struct io_region *where, int rw,
void *data, unsigned long *error_bits);
/*
* Aynchronous IO.
*
* The 'where' array may be safely allocated on the stack since
* the function takes a copy.
*/
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);
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);
int dm_io_async_vm(unsigned int num_regions, struct io_region *where, int rw,
void *data, io_notify_fn fn, void *context);
#endif
......@@ -89,11 +89,6 @@ mempool_t * mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
}
EXPORT_SYMBOL(mempool_create);
/*
* mempool_resize is disabled for now, because it has no callers. Feel free
* to turn it back on if needed.
*/
#if 0
/**
* mempool_resize - resize an existing memory pool
* @pool: pointer to the memory pool which was allocated via
......@@ -163,7 +158,6 @@ int mempool_resize(mempool_t *pool, int new_min_nr, int gfp_mask)
return 0;
}
EXPORT_SYMBOL(mempool_resize);
#endif
/**
* mempool_destroy - deallocate a memory pool
......
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