Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

1289 lines (1076 sloc) 30.691 kb
/*
* Copyright (C) 2001 Jens Axboe <axboe@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public Licens
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-
*
*/
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mempool.h>
#include <linux/workqueue.h>
#include <scsi/sg.h> /* for struct sg_iovec */
#define BIO_POOL_SIZE 256
static kmem_cache_t *bio_slab;
#define BIOVEC_NR_POOLS 6
/*
* a small number of entries is fine, not going to be performance critical.
* basically we just need to survive
*/
#define BIO_SPLIT_ENTRIES 8
mempool_t *bio_split_pool;
struct biovec_slab {
int nr_vecs;
char *name;
kmem_cache_t *slab;
};
/*
* if you change this list, also change bvec_alloc or things will
* break badly! cannot be bigger than what you can fit into an
* unsigned short
*/
#define BV(x) { .nr_vecs = x, .name = "biovec-"__stringify(x) }
static struct biovec_slab bvec_slabs[BIOVEC_NR_POOLS] __read_mostly = {
BV(1), BV(4), BV(16), BV(64), BV(128), BV(BIO_MAX_PAGES),
};
#undef BV
/*
* bio_set is used to allow other portions of the IO system to
* allocate their own private memory pools for bio and iovec structures.
* These memory pools in turn all allocate from the bio_slab
* and the bvec_slabs[].
*/
struct bio_set {
mempool_t *bio_pool;
mempool_t *bvec_pools[BIOVEC_NR_POOLS];
};
/*
* fs_bio_set is the bio_set containing bio and iovec memory pools used by
* IO code that does not need private memory pools.
*/
static struct bio_set *fs_bio_set;
static inline struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx, struct bio_set *bs)
{
struct bio_vec *bvl;
struct biovec_slab *bp;
/*
* see comment near bvec_array define!
*/
switch (nr) {
case 1 : *idx = 0; break;
case 2 ... 4: *idx = 1; break;
case 5 ... 16: *idx = 2; break;
case 17 ... 64: *idx = 3; break;
case 65 ... 128: *idx = 4; break;
case 129 ... BIO_MAX_PAGES: *idx = 5; break;
default:
return NULL;
}
/*
* idx now points to the pool we want to allocate from
*/
bp = bvec_slabs + *idx;
bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask);
if (bvl)
memset(bvl, 0, bp->nr_vecs * sizeof(struct bio_vec));
return bvl;
}
void bio_free(struct bio *bio, struct bio_set *bio_set)
{
const int pool_idx = BIO_POOL_IDX(bio);
BIO_BUG_ON(pool_idx >= BIOVEC_NR_POOLS);
mempool_free(bio->bi_io_vec, bio_set->bvec_pools[pool_idx]);
mempool_free(bio, bio_set->bio_pool);
}
/*
* default destructor for a bio allocated with bio_alloc_bioset()
*/
static void bio_fs_destructor(struct bio *bio)
{
bio_free(bio, fs_bio_set);
}
void bio_init(struct bio *bio)
{
bio->bi_next = NULL;
bio->bi_bdev = 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_hw_front_size = 0;
bio->bi_hw_back_size = 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;
}
/**
* bio_alloc_bioset - allocate a bio for I/O
* @gfp_mask: the GFP_ mask given to the slab allocator
* @nr_iovecs: number of iovecs to pre-allocate
* @bs: the bio_set to allocate from
*
* Description:
* bio_alloc_bioset will first try it's on mempool to satisfy the allocation.
* If %__GFP_WAIT is set then we will block on the internal pool waiting
* for a &struct bio to become free.
*
* allocate bio and iovecs from the memory pools specified by the
* bio_set structure.
**/
struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
{
struct bio *bio = mempool_alloc(bs->bio_pool, gfp_mask);
if (likely(bio)) {
struct bio_vec *bvl = NULL;
bio_init(bio);
if (likely(nr_iovecs)) {
unsigned long idx;
bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
if (unlikely(!bvl)) {
mempool_free(bio, bs->bio_pool);
bio = NULL;
goto out;
}
bio->bi_flags |= idx << BIO_POOL_OFFSET;
bio->bi_max_vecs = bvec_slabs[idx].nr_vecs;
}
bio->bi_io_vec = bvl;
}
out:
return bio;
}
struct bio *bio_alloc(gfp_t gfp_mask, int nr_iovecs)
{
struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, fs_bio_set);
if (bio)
bio->bi_destructor = bio_fs_destructor;
return bio;
}
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);
}
}
EXPORT_SYMBOL(zero_fill_bio);
/**
* bio_put - release a reference to a bio
* @bio: bio to release reference to
*
* Description:
* Put a reference to a &struct bio, either one you have gotten with
* bio_alloc or bio_get. The last put of a bio will free it.
**/
void bio_put(struct bio *bio)
{
BIO_BUG_ON(!atomic_read(&bio->bi_cnt));
/*
* last put frees it
*/
if (atomic_dec_and_test(&bio->bi_cnt)) {
bio->bi_next = NULL;
bio->bi_destructor(bio);
}
}
inline int bio_phys_segments(request_queue_t *q, struct bio *bio)
{
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
blk_recount_segments(q, bio);
return bio->bi_phys_segments;
}
inline int bio_hw_segments(request_queue_t *q, struct bio *bio)
{
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
blk_recount_segments(q, bio);
return bio->bi_hw_segments;
}
/**
* __bio_clone - clone a bio
* @bio: destination bio
* @bio_src: bio to clone
*
* Clone a &bio. Caller will own the returned bio, but not
* the actual data it points to. Reference count of returned
* bio will be one.
*/
void __bio_clone(struct bio *bio, struct bio *bio_src)
{
request_queue_t *q = bdev_get_queue(bio_src->bi_bdev);
memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
bio_src->bi_max_vecs * sizeof(struct bio_vec));
bio->bi_sector = bio_src->bi_sector;
bio->bi_bdev = bio_src->bi_bdev;
bio->bi_flags |= 1 << BIO_CLONED;
bio->bi_rw = bio_src->bi_rw;
bio->bi_vcnt = bio_src->bi_vcnt;
bio->bi_size = bio_src->bi_size;
bio->bi_idx = bio_src->bi_idx;
bio_phys_segments(q, bio);
bio_hw_segments(q, bio);
}
/**
* bio_clone - clone a bio
* @bio: bio to clone
* @gfp_mask: allocation priority
*
* Like __bio_clone, only also allocates the returned bio
*/
struct bio *bio_clone(struct bio *bio, gfp_t gfp_mask)
{
struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, fs_bio_set);
if (b) {
b->bi_destructor = bio_fs_destructor;
__bio_clone(b, bio);
}
return b;
}
/**
* bio_get_nr_vecs - return approx number of vecs
* @bdev: I/O target
*
* Return the approximate number of pages we can send to this target.
* There's no guarantee that you will be able to fit this number of pages
* into a bio, it does not account for dynamic restrictions that vary
* on offset.
*/
int bio_get_nr_vecs(struct block_device *bdev)
{
request_queue_t *q = bdev_get_queue(bdev);
int nr_pages;
nr_pages = ((q->max_sectors << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (nr_pages > q->max_phys_segments)
nr_pages = q->max_phys_segments;
if (nr_pages > q->max_hw_segments)
nr_pages = q->max_hw_segments;
return nr_pages;
}
static int __bio_add_page(request_queue_t *q, struct bio *bio, struct page
*page, unsigned int len, unsigned int offset,
unsigned short max_sectors)
{
int retried_segments = 0;
struct bio_vec *bvec;
/*
* cloned bio must not modify vec list
*/
if (unlikely(bio_flagged(bio, BIO_CLONED)))
return 0;
if (((bio->bi_size + len) >> 9) > max_sectors)
return 0;
/*
* For filesystems with a blocksize smaller than the pagesize
* we will often be called with the same page as last time and
* a consecutive offset. Optimize this special case.
*/
if (bio->bi_vcnt > 0) {
struct bio_vec *prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page == prev->bv_page &&
offset == prev->bv_offset + prev->bv_len) {
prev->bv_len += len;
if (q->merge_bvec_fn &&
q->merge_bvec_fn(q, bio, prev) < len) {
prev->bv_len -= len;
return 0;
}
goto done;
}
}
if (bio->bi_vcnt >= bio->bi_max_vecs)
return 0;
/*
* we might lose a segment or two here, but rather that than
* make this too complex.
*/
while (bio->bi_phys_segments >= q->max_phys_segments
|| bio->bi_hw_segments >= q->max_hw_segments
|| BIOVEC_VIRT_OVERSIZE(bio->bi_size)) {
if (retried_segments)
return 0;
retried_segments = 1;
blk_recount_segments(q, bio);
}
/*
* setup the new entry, we might clear it again later if we
* cannot add the page
*/
bvec = &bio->bi_io_vec[bio->bi_vcnt];
bvec->bv_page = page;
bvec->bv_len = len;
bvec->bv_offset = offset;
/*
* if queue has other restrictions (eg varying max sector size
* depending on offset), it can specify a merge_bvec_fn in the
* queue to get further control
*/
if (q->merge_bvec_fn) {
/*
* merge_bvec_fn() returns number of bytes it can accept
* at this offset
*/
if (q->merge_bvec_fn(q, bio, bvec) < len) {
bvec->bv_page = NULL;
bvec->bv_len = 0;
bvec->bv_offset = 0;
return 0;
}
}
/* If we may be able to merge these biovecs, force a recount */
if (bio->bi_vcnt && (BIOVEC_PHYS_MERGEABLE(bvec-1, bvec) ||
BIOVEC_VIRT_MERGEABLE(bvec-1, bvec)))
bio->bi_flags &= ~(1 << BIO_SEG_VALID);
bio->bi_vcnt++;
bio->bi_phys_segments++;
bio->bi_hw_segments++;
done:
bio->bi_size += len;
return len;
}
/**
* bio_add_pc_page - attempt to add page to bio
* @q: the target queue
* @bio: destination bio
* @page: page to add
* @len: vec entry length
* @offset: vec entry offset
*
* Attempt to add a page to the bio_vec maplist. This can fail for a
* number of reasons, such as the bio being full or target block
* device limitations. The target block device must allow bio's
* smaller than PAGE_SIZE, so it is always possible to add a single
* page to an empty bio. This should only be used by REQ_PC bios.
*/
int bio_add_pc_page(request_queue_t *q, struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
return __bio_add_page(q, bio, page, len, offset, q->max_hw_sectors);
}
/**
* bio_add_page - attempt to add page to bio
* @bio: destination bio
* @page: page to add
* @len: vec entry length
* @offset: vec entry offset
*
* Attempt to add a page to the bio_vec maplist. This can fail for a
* number of reasons, such as the bio being full or target block
* device limitations. The target block device must allow bio's
* smaller than PAGE_SIZE, so it is always possible to add a single
* page to an empty bio.
*/
int bio_add_page(struct bio *bio, struct page *page, unsigned int len,
unsigned int offset)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
return __bio_add_page(q, bio, page, len, offset, q->max_sectors);
}
struct bio_map_data {
struct bio_vec *iovecs;
void __user *userptr;
};
static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio)
{
memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
bio->bi_private = bmd;
}
static void bio_free_map_data(struct bio_map_data *bmd)
{
kfree(bmd->iovecs);
kfree(bmd);
}
static struct bio_map_data *bio_alloc_map_data(int nr_segs)
{
struct bio_map_data *bmd = kmalloc(sizeof(*bmd), GFP_KERNEL);
if (!bmd)
return NULL;
bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, GFP_KERNEL);
if (bmd->iovecs)
return bmd;
kfree(bmd);
return NULL;
}
/**
* bio_uncopy_user - finish previously mapped bio
* @bio: bio being terminated
*
* Free pages allocated from bio_copy_user() and write back data
* to user space in case of a read.
*/
int bio_uncopy_user(struct bio *bio)
{
struct bio_map_data *bmd = bio->bi_private;
const int read = bio_data_dir(bio) == READ;
struct bio_vec *bvec;
int i, ret = 0;
__bio_for_each_segment(bvec, bio, i, 0) {
char *addr = page_address(bvec->bv_page);
unsigned int len = bmd->iovecs[i].bv_len;
if (read && !ret && copy_to_user(bmd->userptr, addr, len))
ret = -EFAULT;
__free_page(bvec->bv_page);
bmd->userptr += len;
}
bio_free_map_data(bmd);
bio_put(bio);
return ret;
}
/**
* bio_copy_user - copy user data to bio
* @q: destination block queue
* @uaddr: start of user address
* @len: length in bytes
* @write_to_vm: bool indicating writing to pages or not
*
* Prepares and returns a bio for indirect user io, bouncing data
* to/from kernel pages as necessary. Must be paired with
* call bio_uncopy_user() on io completion.
*/
struct bio *bio_copy_user(request_queue_t *q, unsigned long uaddr,
unsigned int len, int write_to_vm)
{
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
struct bio_map_data *bmd;
struct bio_vec *bvec;
struct page *page;
struct bio *bio;
int i, ret;
bmd = bio_alloc_map_data(end - start);
if (!bmd)
return ERR_PTR(-ENOMEM);
bmd->userptr = (void __user *) uaddr;
ret = -ENOMEM;
bio = bio_alloc(GFP_KERNEL, end - start);
if (!bio)
goto out_bmd;
bio->bi_rw |= (!write_to_vm << BIO_RW);
ret = 0;
while (len) {
unsigned int bytes = PAGE_SIZE;
if (bytes > len)
bytes = len;
page = alloc_page(q->bounce_gfp | GFP_KERNEL);
if (!page) {
ret = -ENOMEM;
break;
}
if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes) {
ret = -EINVAL;
break;
}
len -= bytes;
}
if (ret)
goto cleanup;
/*
* success
*/
if (!write_to_vm) {
char __user *p = (char __user *) uaddr;
/*
* for a write, copy in data to kernel pages
*/
ret = -EFAULT;
bio_for_each_segment(bvec, bio, i) {
char *addr = page_address(bvec->bv_page);
if (copy_from_user(addr, p, bvec->bv_len))
goto cleanup;
p += bvec->bv_len;
}
}
bio_set_map_data(bmd, bio);
return bio;
cleanup:
bio_for_each_segment(bvec, bio, i)
__free_page(bvec->bv_page);
bio_put(bio);
out_bmd:
bio_free_map_data(bmd);
return ERR_PTR(ret);
}
static struct bio *__bio_map_user_iov(request_queue_t *q,
struct block_device *bdev,
struct sg_iovec *iov, int iov_count,
int write_to_vm)
{
int i, j;
int nr_pages = 0;
struct page **pages;
struct bio *bio;
int cur_page = 0;
int ret, offset;
for (i = 0; i < iov_count; i++) {
unsigned long uaddr = (unsigned long)iov[i].iov_base;
unsigned long len = iov[i].iov_len;
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
nr_pages += end - start;
/*
* transfer and buffer must be aligned to at least hardsector
* size for now, in the future we can relax this restriction
*/
if ((uaddr & queue_dma_alignment(q)) || (len & queue_dma_alignment(q)))
return ERR_PTR(-EINVAL);
}
if (!nr_pages)
return ERR_PTR(-EINVAL);
bio = bio_alloc(GFP_KERNEL, nr_pages);
if (!bio)
return ERR_PTR(-ENOMEM);
ret = -ENOMEM;
pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL);
if (!pages)
goto out;
memset(pages, 0, nr_pages * sizeof(struct page *));
for (i = 0; i < iov_count; i++) {
unsigned long uaddr = (unsigned long)iov[i].iov_base;
unsigned long len = iov[i].iov_len;
unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = uaddr >> PAGE_SHIFT;
const int local_nr_pages = end - start;
const int page_limit = cur_page + local_nr_pages;
down_read(&current->mm->mmap_sem);
ret = get_user_pages(current, current->mm, uaddr,
local_nr_pages,
write_to_vm, 0, &pages[cur_page], NULL);
up_read(&current->mm->mmap_sem);
if (ret < local_nr_pages)
goto out_unmap;
offset = uaddr & ~PAGE_MASK;
for (j = cur_page; j < page_limit; j++) {
unsigned int bytes = PAGE_SIZE - offset;
if (len <= 0)
break;
if (bytes > len)
bytes = len;
/*
* sorry...
*/
if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
bytes)
break;
len -= bytes;
offset = 0;
}
cur_page = j;
/*
* release the pages we didn't map into the bio, if any
*/
while (j < page_limit)
page_cache_release(pages[j++]);
}
kfree(pages);
/*
* set data direction, and check if mapped pages need bouncing
*/
if (!write_to_vm)
bio->bi_rw |= (1 << BIO_RW);
bio->bi_bdev = bdev;
bio->bi_flags |= (1 << BIO_USER_MAPPED);
return bio;
out_unmap:
for (i = 0; i < nr_pages; i++) {
if(!pages[i])
break;
page_cache_release(pages[i]);
}
out:
kfree(pages);
bio_put(bio);
return ERR_PTR(ret);
}
/**
* bio_map_user - map user address into bio
* @q: the request_queue_t for the bio
* @bdev: destination block device
* @uaddr: start of user address
* @len: length in bytes
* @write_to_vm: bool indicating writing to pages or not
*
* Map the user space address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_map_user(request_queue_t *q, struct block_device *bdev,
unsigned long uaddr, unsigned int len, int write_to_vm)
{
struct sg_iovec iov;
iov.iov_base = (void __user *)uaddr;
iov.iov_len = len;
return bio_map_user_iov(q, bdev, &iov, 1, write_to_vm);
}
/**
* bio_map_user_iov - map user sg_iovec table into bio
* @q: the request_queue_t for the bio
* @bdev: destination block device
* @iov: the iovec.
* @iov_count: number of elements in the iovec
* @write_to_vm: bool indicating writing to pages or not
*
* Map the user space address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_map_user_iov(request_queue_t *q, struct block_device *bdev,
struct sg_iovec *iov, int iov_count,
int write_to_vm)
{
struct bio *bio;
int len = 0, i;
bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm);
if (IS_ERR(bio))
return bio;
/*
* subtle -- if __bio_map_user() ended up bouncing a bio,
* it would normally disappear when its bi_end_io is run.
* however, we need it for the unmap, so grab an extra
* reference to it
*/
bio_get(bio);
for (i = 0; i < iov_count; i++)
len += iov[i].iov_len;
if (bio->bi_size == len)
return bio;
/*
* don't support partial mappings
*/
bio_endio(bio, bio->bi_size, 0);
bio_unmap_user(bio);
return ERR_PTR(-EINVAL);
}
static void __bio_unmap_user(struct bio *bio)
{
struct bio_vec *bvec;
int i;
/*
* make sure we dirty pages we wrote to
*/
__bio_for_each_segment(bvec, bio, i, 0) {
if (bio_data_dir(bio) == READ)
set_page_dirty_lock(bvec->bv_page);
page_cache_release(bvec->bv_page);
}
bio_put(bio);
}
/**
* bio_unmap_user - unmap a bio
* @bio: the bio being unmapped
*
* Unmap a bio previously mapped by bio_map_user(). Must be called with
* a process context.
*
* bio_unmap_user() may sleep.
*/
void bio_unmap_user(struct bio *bio)
{
__bio_unmap_user(bio);
bio_put(bio);
}
static int bio_map_kern_endio(struct bio *bio, unsigned int bytes_done, int err)
{
if (bio->bi_size)
return 1;
bio_put(bio);
return 0;
}
static struct bio *__bio_map_kern(request_queue_t *q, void *data,
unsigned int len, gfp_t gfp_mask)
{
unsigned long kaddr = (unsigned long)data;
unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned long start = kaddr >> PAGE_SHIFT;
const int nr_pages = end - start;
int offset, i;
struct bio *bio;
bio = bio_alloc(gfp_mask, nr_pages);
if (!bio)
return ERR_PTR(-ENOMEM);
offset = offset_in_page(kaddr);
for (i = 0; i < nr_pages; i++) {
unsigned int bytes = PAGE_SIZE - offset;
if (len <= 0)
break;
if (bytes > len)
bytes = len;
if (bio_add_pc_page(q, bio, virt_to_page(data), bytes,
offset) < bytes)
break;
data += bytes;
len -= bytes;
offset = 0;
}
bio->bi_end_io = bio_map_kern_endio;
return bio;
}
/**
* bio_map_kern - map kernel address into bio
* @q: the request_queue_t for the bio
* @data: pointer to buffer to map
* @len: length in bytes
* @gfp_mask: allocation flags for bio allocation
*
* Map the kernel address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_map_kern(request_queue_t *q, void *data, unsigned int len,
gfp_t gfp_mask)
{
struct bio *bio;
bio = __bio_map_kern(q, data, len, gfp_mask);
if (IS_ERR(bio))
return bio;
if (bio->bi_size == len)
return bio;
/*
* Don't support partial mappings.
*/
bio_put(bio);
return ERR_PTR(-EINVAL);
}
/*
* bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
* for performing direct-IO in BIOs.
*
* The problem is that we cannot run set_page_dirty() from interrupt context
* because the required locks are not interrupt-safe. So what we can do is to
* mark the pages dirty _before_ performing IO. And in interrupt context,
* check that the pages are still dirty. If so, fine. If not, redirty them
* in process context.
*
* We special-case compound pages here: normally this means reads into hugetlb
* pages. The logic in here doesn't really work right for compound pages
* because the VM does not uniformly chase down the head page in all cases.
* But dirtiness of compound pages is pretty meaningless anyway: the VM doesn't
* handle them at all. So we skip compound pages here at an early stage.
*
* Note that this code is very hard to test under normal circumstances because
* direct-io pins the pages with get_user_pages(). This makes
* is_page_cache_freeable return false, and the VM will not clean the pages.
* But other code (eg, pdflush) could clean the pages if they are mapped
* pagecache.
*
* Simply disabling the call to bio_set_pages_dirty() is a good way to test the
* deferred bio dirtying paths.
*/
/*
* bio_set_pages_dirty() will mark all the bio's pages as dirty.
*/
void bio_set_pages_dirty(struct bio *bio)
{
struct bio_vec *bvec = bio->bi_io_vec;
int i;
for (i = 0; i < bio->bi_vcnt; i++) {
struct page *page = bvec[i].bv_page;
if (page && !PageCompound(page))
set_page_dirty_lock(page);
}
}
static void bio_release_pages(struct bio *bio)
{
struct bio_vec *bvec = bio->bi_io_vec;
int i;
for (i = 0; i < bio->bi_vcnt; i++) {
struct page *page = bvec[i].bv_page;
if (page)
put_page(page);
}
}
/*
* bio_check_pages_dirty() will check that all the BIO's pages are still dirty.
* If they are, then fine. If, however, some pages are clean then they must
* have been written out during the direct-IO read. So we take another ref on
* the BIO and the offending pages and re-dirty the pages in process context.
*
* It is expected that bio_check_pages_dirty() will wholly own the BIO from
* here on. It will run one page_cache_release() against each page and will
* run one bio_put() against the BIO.
*/
static void bio_dirty_fn(void *data);
static DECLARE_WORK(bio_dirty_work, bio_dirty_fn, NULL);
static DEFINE_SPINLOCK(bio_dirty_lock);
static struct bio *bio_dirty_list;
/*
* This runs in process context
*/
static void bio_dirty_fn(void *data)
{
unsigned long flags;
struct bio *bio;
spin_lock_irqsave(&bio_dirty_lock, flags);
bio = bio_dirty_list;
bio_dirty_list = NULL;
spin_unlock_irqrestore(&bio_dirty_lock, flags);
while (bio) {
struct bio *next = bio->bi_private;
bio_set_pages_dirty(bio);
bio_release_pages(bio);
bio_put(bio);
bio = next;
}
}
void bio_check_pages_dirty(struct bio *bio)
{
struct bio_vec *bvec = bio->bi_io_vec;
int nr_clean_pages = 0;
int i;
for (i = 0; i < bio->bi_vcnt; i++) {
struct page *page = bvec[i].bv_page;
if (PageDirty(page) || PageCompound(page)) {
page_cache_release(page);
bvec[i].bv_page = NULL;
} else {
nr_clean_pages++;
}
}
if (nr_clean_pages) {
unsigned long flags;
spin_lock_irqsave(&bio_dirty_lock, flags);
bio->bi_private = bio_dirty_list;
bio_dirty_list = bio;
spin_unlock_irqrestore(&bio_dirty_lock, flags);
schedule_work(&bio_dirty_work);
} else {
bio_put(bio);
}
}
/**
* bio_endio - end I/O on a bio
* @bio: bio
* @bytes_done: number of bytes completed
* @error: error, if any
*
* Description:
* bio_endio() will end I/O on @bytes_done number of bytes. This may be
* just a partial part of the bio, or it may be the whole bio. bio_endio()
* is the preferred way to end I/O on a bio, it takes care of decrementing
* bi_size and clearing BIO_UPTODATE on error. @error is 0 on success, and
* and one of the established -Exxxx (-EIO, for instance) error values in
* case something went wrong. Noone should call bi_end_io() directly on
* a bio unless they own it and thus know that it has an end_io function.
**/
void bio_endio(struct bio *bio, unsigned int bytes_done, int error)
{
if (error)
clear_bit(BIO_UPTODATE, &bio->bi_flags);
if (unlikely(bytes_done > bio->bi_size)) {
printk("%s: want %u bytes done, only %u left\n", __FUNCTION__,
bytes_done, bio->bi_size);
bytes_done = bio->bi_size;
}
bio->bi_size -= bytes_done;
bio->bi_sector += (bytes_done >> 9);
if (bio->bi_end_io)
bio->bi_end_io(bio, bytes_done, error);
}
void bio_pair_release(struct bio_pair *bp)
{
if (atomic_dec_and_test(&bp->cnt)) {
struct bio *master = bp->bio1.bi_private;
bio_endio(master, master->bi_size, bp->error);
mempool_free(bp, bp->bio2.bi_private);
}
}
static int bio_pair_end_1(struct bio * bi, unsigned int done, int err)
{
struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
if (err)
bp->error = err;
if (bi->bi_size)
return 1;
bio_pair_release(bp);
return 0;
}
static int bio_pair_end_2(struct bio * bi, unsigned int done, int err)
{
struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
if (err)
bp->error = err;
if (bi->bi_size)
return 1;
bio_pair_release(bp);
return 0;
}
/*
* split a bio - only worry about a bio with a single page
* in it's iovec
*/
struct bio_pair *bio_split(struct bio *bi, mempool_t *pool, int first_sectors)
{
struct bio_pair *bp = mempool_alloc(pool, GFP_NOIO);
if (!bp)
return bp;
BUG_ON(bi->bi_vcnt != 1);
BUG_ON(bi->bi_idx != 0);
atomic_set(&bp->cnt, 3);
bp->error = 0;
bp->bio1 = *bi;
bp->bio2 = *bi;
bp->bio2.bi_sector += first_sectors;
bp->bio2.bi_size -= first_sectors << 9;
bp->bio1.bi_size = first_sectors << 9;
bp->bv1 = bi->bi_io_vec[0];
bp->bv2 = bi->bi_io_vec[0];
bp->bv2.bv_offset += first_sectors << 9;
bp->bv2.bv_len -= first_sectors << 9;
bp->bv1.bv_len = first_sectors << 9;
bp->bio1.bi_io_vec = &bp->bv1;
bp->bio2.bi_io_vec = &bp->bv2;
bp->bio1.bi_end_io = bio_pair_end_1;
bp->bio2.bi_end_io = bio_pair_end_2;
bp->bio1.bi_private = bi;
bp->bio2.bi_private = pool;
return bp;
}
static void *bio_pair_alloc(gfp_t gfp_flags, void *data)
{
return kmalloc(sizeof(struct bio_pair), gfp_flags);
}
static void bio_pair_free(void *bp, void *data)
{
kfree(bp);
}
/*
* create memory pools for biovec's in a bio_set.
* use the global biovec slabs created for general use.
*/
static int biovec_create_pools(struct bio_set *bs, int pool_entries, int scale)
{
int i;
for (i = 0; i < BIOVEC_NR_POOLS; i++) {
struct biovec_slab *bp = bvec_slabs + i;
mempool_t **bvp = bs->bvec_pools + i;
if (i >= scale)
pool_entries >>= 1;
*bvp = mempool_create(pool_entries, mempool_alloc_slab,
mempool_free_slab, bp->slab);
if (!*bvp)
return -ENOMEM;
}
return 0;
}
static void biovec_free_pools(struct bio_set *bs)
{
int i;
for (i = 0; i < BIOVEC_NR_POOLS; i++) {
mempool_t *bvp = bs->bvec_pools[i];
if (bvp)
mempool_destroy(bvp);
}
}
void bioset_free(struct bio_set *bs)
{
if (bs->bio_pool)
mempool_destroy(bs->bio_pool);
biovec_free_pools(bs);
kfree(bs);
}
struct bio_set *bioset_create(int bio_pool_size, int bvec_pool_size, int scale)
{
struct bio_set *bs = kmalloc(sizeof(*bs), GFP_KERNEL);
if (!bs)
return NULL;
memset(bs, 0, sizeof(*bs));
bs->bio_pool = mempool_create(bio_pool_size, mempool_alloc_slab,
mempool_free_slab, bio_slab);
if (!bs->bio_pool)
goto bad;
if (!biovec_create_pools(bs, bvec_pool_size, scale))
return bs;
bad:
bioset_free(bs);
return NULL;
}
static void __init biovec_init_slabs(void)
{
int i;
for (i = 0; i < BIOVEC_NR_POOLS; i++) {
int size;
struct biovec_slab *bvs = bvec_slabs + i;
size = bvs->nr_vecs * sizeof(struct bio_vec);
bvs->slab = kmem_cache_create(bvs->name, size, 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
}
}
static int __init init_bio(void)
{
int megabytes, bvec_pool_entries;
int scale = BIOVEC_NR_POOLS;
bio_slab = kmem_cache_create("bio", sizeof(struct bio), 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
biovec_init_slabs();
megabytes = nr_free_pages() >> (20 - PAGE_SHIFT);
/*
* find out where to start scaling
*/
if (megabytes <= 16)
scale = 0;
else if (megabytes <= 32)
scale = 1;
else if (megabytes <= 64)
scale = 2;
else if (megabytes <= 96)
scale = 3;
else if (megabytes <= 128)
scale = 4;
/*
* scale number of entries
*/
bvec_pool_entries = megabytes * 2;
if (bvec_pool_entries > 256)
bvec_pool_entries = 256;
fs_bio_set = bioset_create(BIO_POOL_SIZE, bvec_pool_entries, scale);
if (!fs_bio_set)
panic("bio: can't allocate bios\n");
bio_split_pool = mempool_create(BIO_SPLIT_ENTRIES,
bio_pair_alloc, bio_pair_free, NULL);
if (!bio_split_pool)
panic("bio: can't create split pool\n");
return 0;
}
subsys_initcall(init_bio);
EXPORT_SYMBOL(bio_alloc);
EXPORT_SYMBOL(bio_put);
EXPORT_SYMBOL(bio_free);
EXPORT_SYMBOL(bio_endio);
EXPORT_SYMBOL(bio_init);
EXPORT_SYMBOL(__bio_clone);
EXPORT_SYMBOL(bio_clone);
EXPORT_SYMBOL(bio_phys_segments);
EXPORT_SYMBOL(bio_hw_segments);
EXPORT_SYMBOL(bio_add_page);
EXPORT_SYMBOL(bio_add_pc_page);
EXPORT_SYMBOL(bio_get_nr_vecs);
EXPORT_SYMBOL(bio_map_user);
EXPORT_SYMBOL(bio_unmap_user);
EXPORT_SYMBOL(bio_map_kern);
EXPORT_SYMBOL(bio_pair_release);
EXPORT_SYMBOL(bio_split);
EXPORT_SYMBOL(bio_split_pool);
EXPORT_SYMBOL(bio_copy_user);
EXPORT_SYMBOL(bio_uncopy_user);
EXPORT_SYMBOL(bioset_create);
EXPORT_SYMBOL(bioset_free);
EXPORT_SYMBOL(bio_alloc_bioset);
Jump to Line
Something went wrong with that request. Please try again.