519 lines
12 KiB
C
519 lines
12 KiB
C
/*
|
|
* Copyright (C) 2003 Sistina Software
|
|
* Copyright (C) 2006 Red Hat GmbH
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#include "dm.h"
|
|
|
|
#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>
|
|
|
|
#define DM_MSG_PREFIX "io"
|
|
|
|
#define DM_IO_MAX_REGIONS BITS_PER_LONG
|
|
|
|
struct dm_io_client {
|
|
mempool_t *pool;
|
|
struct bio_set *bios;
|
|
};
|
|
|
|
/*
|
|
* Aligning 'struct io' reduces the number of bits required to store
|
|
* its address. Refer to store_io_and_region_in_bio() below.
|
|
*/
|
|
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;
|
|
} __attribute__((aligned(DM_IO_MAX_REGIONS)));
|
|
|
|
static struct kmem_cache *_dm_io_cache;
|
|
|
|
/*
|
|
* 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_slab_pool(ios, _dm_io_cache);
|
|
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.
|
|
* To avoid a memory allocation to store just 5 or 6 bits, we
|
|
* ensure the 'struct io' pointer is aligned so enough low bits are
|
|
* always zero and then combine it with the region number directly in
|
|
* bi_private.
|
|
*---------------------------------------------------------------*/
|
|
static void store_io_and_region_in_bio(struct bio *bio, struct io *io,
|
|
unsigned region)
|
|
{
|
|
if (unlikely(!IS_ALIGNED((unsigned long)io, DM_IO_MAX_REGIONS))) {
|
|
DMCRIT("Unaligned struct io pointer %p", io);
|
|
BUG();
|
|
}
|
|
|
|
bio->bi_private = (void *)((unsigned long)io | region);
|
|
}
|
|
|
|
static void retrieve_io_and_region_from_bio(struct bio *bio, struct io **io,
|
|
unsigned *region)
|
|
{
|
|
unsigned long val = (unsigned long)bio->bi_private;
|
|
|
|
*io = (void *)(val & -(unsigned long)DM_IO_MAX_REGIONS);
|
|
*region = val & (DM_IO_MAX_REGIONS - 1);
|
|
}
|
|
|
|
/*-----------------------------------------------------------------
|
|
* 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.
|
|
*/
|
|
retrieve_io_and_region_from_bio(bio, &io, ®ion);
|
|
|
|
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)
|
|
{
|
|
unsigned region;
|
|
struct io *io;
|
|
|
|
retrieve_io_and_region_from_bio(bio, &io, ®ion);
|
|
|
|
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;
|
|
|
|
/*
|
|
* where->count may be zero if rw holds a write barrier and we
|
|
* need to send a zero-sized barrier.
|
|
*/
|
|
do {
|
|
/*
|
|
* Allocate a suitably sized-bio.
|
|
*/
|
|
num_bvecs = dm_sector_div_up(remaining,
|
|
(PAGE_SIZE >> SECTOR_SHIFT));
|
|
num_bvecs = 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_destructor = dm_bio_destructor;
|
|
store_io_and_region_in_bio(bio, io, 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);
|
|
} while (remaining);
|
|
}
|
|
|
|
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;
|
|
|
|
BUG_ON(num_regions > DM_IO_MAX_REGIONS);
|
|
|
|
if (sync)
|
|
rw |= REQ_SYNC | REQ_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 || (rw & REQ_HARDBARRIER))
|
|
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)
|
|
{
|
|
/*
|
|
* gcc <= 4.3 can't do the alignment for stack variables, so we must
|
|
* align it on our own.
|
|
* volatile prevents the optimizer from removing or reusing
|
|
* "io_" field from the stack frame (allowed in ANSI C).
|
|
*/
|
|
volatile char io_[sizeof(struct io) + __alignof__(struct io) - 1];
|
|
struct io *io = (struct io *)PTR_ALIGN(&io_, __alignof__(struct 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 & REQ_HARDBARRIER)) {
|
|
rw &= ~REQ_HARDBARRIER;
|
|
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 REQ_SYNC 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);
|
|
|
|
int __init dm_io_init(void)
|
|
{
|
|
_dm_io_cache = KMEM_CACHE(io, 0);
|
|
if (!_dm_io_cache)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void dm_io_exit(void)
|
|
{
|
|
kmem_cache_destroy(_dm_io_cache);
|
|
_dm_io_cache = NULL;
|
|
}
|