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linux/fs/bio.c

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/*
* Copyright (C) 2001 Jens Axboe <axboe@kernel.dk>
*
* 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 <linux/blktrace_api.h>
#include <scsi/sg.h> /* for struct sg_iovec */
#define BIO_POOL_SIZE 256
static struct kmem_cache *bio_slab __read_mostly;
#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 __read_mostly;
struct biovec_slab {
int nr_vecs;
char *name;
struct kmem_cache *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;
/*
* 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
*/
bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask);
if (bvl) {
struct biovec_slab *bp = bvec_slabs + *idx;
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 = 0; /* shut up gcc */
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)
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;
/*
* buffer must be aligned to at least hardsector size for now
*/
if (uaddr & 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 = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
if (!pages)
goto out;
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) {
ret = -EFAULT;
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;
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);
return bio;
}
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);
}
}
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(struct work_struct *work);
static DECLARE_WORK(bio_dirty_work, bio_dirty_fn);
static DEFINE_SPINLOCK(bio_dirty_lock);
static struct bio *bio_dirty_list;
/*
* This runs in process context
*/
static void bio_dirty_fn(struct work_struct *work)
{
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;
blk_add_trace_pdu_int(bdev_get_queue(bi->bi_bdev), BLK_TA_SPLIT, bi,
bi->bi_sector + first_sectors);
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_max_vecs = 1;
bp->bio2.bi_max_vecs = 1;
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;
}
/*
* 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 (pool_entries > 1 && i >= scale)
pool_entries >>= 1;
*bvp = mempool_create_slab_pool(pool_entries, 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 = kzalloc(sizeof(*bs), GFP_KERNEL);
if (!bs)
return NULL;
bs->bio_pool = mempool_create_slab_pool(bio_pool_size, 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;
/*
* Limit number of entries reserved -- mempools are only used when
* the system is completely unable to allocate memory, so we only
* need enough to make progress.
*/
bvec_pool_entries = 1 + scale;
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_kmalloc_pool(BIO_SPLIT_ENTRIES,
sizeof(struct bio_pair));
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);
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