- 根目录:
- 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.h"
#include <linux/device-mapper.h>
#include <linux/bio.h>
#include <linux/completion.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;
atomic_t count;
struct dm_io_client *client;
io_notify_fn callback;
void *context;
void *vma_invalidate_address;
unsigned long vma_invalidate_size;
} __attribute__((aligned(DM_IO_MAX_REGIONS)));
static struct kmem_cache *_dm_io_cache;
/*
* Create a client with mempool and bioset.
*/
struct dm_io_client *dm_io_client_create(void)
{
struct dm_io_client *client;
unsigned min_ios = dm_get_reserved_bio_based_ios();
client = kmalloc(sizeof(*client), GFP_KERNEL);
if (!client)
return ERR_PTR(-ENOMEM);
client->pool = mempool_create_slab_pool(min_ios, _dm_io_cache);
if (!client->pool)
goto bad;
client->bios = bioset_create(min_ios, 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);
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 complete_io(struct io *io)
{
unsigned long error_bits = io->error_bits;
io_notify_fn fn = io->callback;
void *context = io->context;
if (io->vma_invalidate_size)
invalidate_kernel_vmap_range(io->vma_invalidate_address,
io->vma_invalidate_size);
mempool_free(io, io->client->pool);
fn(error_bits, context);
}
static void dec_count(struct io *io, unsigned int region, int error)
{
if (error)
set_bit(region, &io->error_bits);
if (atomic_dec_and_test(&io->count))
complete_io(io);
}
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;
void *vma_invalidate_address;
unsigned long vma_invalidate_size;
};
/*
* 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 bio_get_page(struct dpages *dp, struct page **p,
unsigned long *len, unsigned *offset)
{
struct bio_vec *bvec = dp->context_ptr;
*p = bvec->bv_page;
*len = bvec->bv_len - dp->context_u;
*offset = bvec->bv_offset + dp->context_u;
}
static void bio_next_page(struct dpages *dp)
{
struct bio_vec *bvec = dp->context_ptr;
dp->context_ptr = bvec + 1;
dp->context_u = 0;
}
static void bio_dp_init(struct dpages *dp, struct bio *bio)
{
dp->get_page = bio_get_page;
dp->next_page = bio_next_page;
dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
dp->context_u = bio->bi_iter.bi_bvec_done;
}
/*
* 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;
}
/*
* 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;
struct request_queue *q = bdev_get_queue(where->bdev);
unsigned short logical_block_size = queue_logical_block_size(q);
sector_t num_sectors;
/*
* where->count may be zero if rw holds a flush and we need to
* send a zero-sized flush.
*/
do {
/*
* Allocate a suitably sized-bio.
*/
if ((rw & REQ_DISCARD) || (rw & REQ_WRITE_SAME))
num_bvecs = 1;
else
num_bvecs = min_t(int, bio_get_nr_vecs(where->bdev),
dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT)));
bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios);
bio->bi_iter.bi_sector = where->sector + (where->count - remaining);
bio->bi_bdev = where->bdev;
bio->bi_end_io = endio;
store_io_and_region_in_bio(bio, io, region);
if (rw & REQ_DISCARD) {
num_sectors = min_t(sector_t, q->limits.max_discard_sectors, remaining);
bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
remaining -= num_sectors;
} else if (rw & REQ_WRITE_SAME) {
/*
* WRITE SAME only uses a single page.
*/
dp->get_page(dp, &page, &len, &offset);
bio_add_page(bio, page, logical_block_size, offset);
num_sectors = min_t(sector_t, q->limits.max_write_same_sectors, remaining);
bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
offset = 0;
remaining -= num_sectors;
dp->next_page(dp);
} else while (remaining) {
/*
* Try and add as many pages as possible.
*/
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;
/*
* 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_FLUSH))
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);
}
struct sync_io {
unsigned long error_bits;
struct completion wait;
};
static void sync_io_complete(unsigned long error, void *context)
{
struct sync_io *sio = context;
sio->error_bits = error;
complete(&sio->wait);
}
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;
struct sync_io sio;
if (num_regions > 1 && (rw & RW_MASK) != WRITE) {
WARN_ON(1);
return -EIO;
}
init_completion(&sio.wait);
io = mempool_alloc(client->pool, GFP_NOIO);
io->error_bits = 0;
atomic_set(&io->count, 1); /* see dispatch_io() */
io->client = client;
io->callback = sync_io_complete;
io->context = &sio;
io->vma_invalidate_address = dp->vma_invalidate_address;
io->vma_invalidate_size = dp->vma_invalidate_size;
dispatch_io(rw, num_regions, where, dp, io, 1);
wait_for_completion_io(&sio.wait);
if (error_bits)
*error_bits = sio.error_bits;
return sio.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;
atomic_set(&io->count, 1); /* see dispatch_io() */
io->client = client;
io->callback = fn;
io->context = context;
io->vma_invalidate_address = dp->vma_invalidate_address;
io->vma_invalidate_size = dp->vma_invalidate_size;
dispatch_io(rw, num_regions, where, dp, io, 0);
return 0;
}
static int dp_init(struct dm_io_request *io_req, struct dpages *dp,
unsigned long size)
{
/* Set up dpages based on memory type */
dp->vma_invalidate_address = NULL;
dp->vma_invalidate_size = 0;
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_BIO:
bio_dp_init(dp, io_req->mem.ptr.bio);
break;
case DM_IO_VMA:
flush_kernel_vmap_range(io_req->mem.ptr.vma, size);
if ((io_req->bi_rw & RW_MASK) == READ) {
dp->vma_invalidate_address = io_req->mem.ptr.vma;
dp->vma_invalidate_size = size;
}
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, (unsigned long)where->count << SECTOR_SHIFT);
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;
}