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9f7cdbc33f
linux/fs/bio.c
Dmitry Monakhov 9f7cdbc33f blkdev: fix merge_bvec_fn return value checks 
merge_bvec_fn() returns bvec->bv_len on success. So we have to check
against this value. But in case of fs_optimization merge we compare
with wrong value. This patch must be included in
 b428cd6da7e6559aca69aa2e3a526037d3f20403
But accidentally i've forgot to add this in the initial patch.
To make things straight let's replace all such checks.
In fact this makes code easy to understand.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2010-02-28 19:47:18 +01:00

1676 lines
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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 <scsi/sg.h> /* for struct sg_iovec */
#include <trace/events/block.h>
/*
* Test patch to inline a certain number of bi_io_vec's inside the bio
* itself, to shrink a bio data allocation from two mempool calls to one
*/
#define BIO_INLINE_VECS 4
static mempool_t *bio_split_pool __read_mostly;
/*
* 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) }
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
/*
* fs_bio_set is the bio_set containing bio and iovec memory pools used by
* IO code that does not need private memory pools.
*/
struct bio_set *fs_bio_set;
/*
* Our slab pool management
*/
struct bio_slab {
struct kmem_cache *slab;
unsigned int slab_ref;
unsigned int slab_size;
char name[8];
};
static DEFINE_MUTEX(bio_slab_lock);
static struct bio_slab *bio_slabs;
static unsigned int bio_slab_nr, bio_slab_max;
static struct kmem_cache *bio_find_or_create_slab(unsigned int extra_size)
{
unsigned int sz = sizeof(struct bio) + extra_size;
struct kmem_cache *slab = NULL;
struct bio_slab *bslab;
unsigned int i, entry = -1;
mutex_lock(&bio_slab_lock);
i = 0;
while (i < bio_slab_nr) {
bslab = &bio_slabs[i];
if (!bslab->slab && entry == -1)
entry = i;
else if (bslab->slab_size == sz) {
slab = bslab->slab;
bslab->slab_ref++;
break;
}
i++;
}
if (slab)
goto out_unlock;
if (bio_slab_nr == bio_slab_max && entry == -1) {
bio_slab_max <<= 1;
bio_slabs = krealloc(bio_slabs,
bio_slab_max * sizeof(struct bio_slab),
GFP_KERNEL);
if (!bio_slabs)
goto out_unlock;
}
if (entry == -1)
entry = bio_slab_nr++;
bslab = &bio_slabs[entry];
snprintf(bslab->name, sizeof(bslab->name), "bio-%d", entry);
slab = kmem_cache_create(bslab->name, sz, 0, SLAB_HWCACHE_ALIGN, NULL);
if (!slab)
goto out_unlock;
printk("bio: create slab <%s> at %d\n", bslab->name, entry);
bslab->slab = slab;
bslab->slab_ref = 1;
bslab->slab_size = sz;
out_unlock:
mutex_unlock(&bio_slab_lock);
return slab;
}
static void bio_put_slab(struct bio_set *bs)
{
struct bio_slab *bslab = NULL;
unsigned int i;
mutex_lock(&bio_slab_lock);
for (i = 0; i < bio_slab_nr; i++) {
if (bs->bio_slab == bio_slabs[i].slab) {
bslab = &bio_slabs[i];
break;
}
}
if (WARN(!bslab, KERN_ERR "bio: unable to find slab!\n"))
goto out;
WARN_ON(!bslab->slab_ref);
if (--bslab->slab_ref)
goto out;
kmem_cache_destroy(bslab->slab);
bslab->slab = NULL;
out:
mutex_unlock(&bio_slab_lock);
}
unsigned int bvec_nr_vecs(unsigned short idx)
{
return bvec_slabs[idx].nr_vecs;
}
void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
{
BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
if (idx == BIOVEC_MAX_IDX)
mempool_free(bv, bs->bvec_pool);
else {
struct biovec_slab *bvs = bvec_slabs + idx;
kmem_cache_free(bvs->slab, bv);
}
}
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. only the
* 1-vec entry pool is mempool backed.
*/
if (*idx == BIOVEC_MAX_IDX) {
fallback:
bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
} else {
struct biovec_slab *bvs = bvec_slabs + *idx;
gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
/*
* Make this allocation restricted and don't dump info on
* allocation failures, since we'll fallback to the mempool
* in case of failure.
*/
__gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
/*
* Try a slab allocation. If this fails and __GFP_WAIT
* is set, retry with the 1-entry mempool
*/
bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
*idx = BIOVEC_MAX_IDX;
goto fallback;
}
}
return bvl;
}
void bio_free(struct bio *bio, struct bio_set *bs)
{
void *p;
if (bio_has_allocated_vec(bio))
bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
if (bio_integrity(bio))
bio_integrity_free(bio, bs);
/*
* If we have front padding, adjust the bio pointer before freeing
*/
p = bio;
if (bs->front_pad)
p -= bs->front_pad;
mempool_free(p, bs->bio_pool);
}
EXPORT_SYMBOL(bio_free);
void bio_init(struct bio *bio)
{
memset(bio, 0, sizeof(*bio));
bio->bi_flags = 1 << BIO_UPTODATE;
bio->bi_comp_cpu = -1;
atomic_set(&bio->bi_cnt, 1);
}
EXPORT_SYMBOL(bio_init);
/**
* 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. If %NULL, just use kmalloc
*
* Description:
* bio_alloc_bioset will first try its own 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. If a %NULL @bs is passed in, we will
* fall back to just using @kmalloc to allocate the required memory.
*
* Note that the caller must set ->bi_destructor on successful return
* of a bio, to do the appropriate freeing of the bio once the reference
* count drops to zero.
**/
struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
{
unsigned long idx = BIO_POOL_NONE;
struct bio_vec *bvl = NULL;
struct bio *bio;
void *p;
p = mempool_alloc(bs->bio_pool, gfp_mask);
if (unlikely(!p))
return NULL;
bio = p + bs->front_pad;
bio_init(bio);
if (unlikely(!nr_iovecs))
goto out_set;
if (nr_iovecs <= BIO_INLINE_VECS) {
bvl = bio->bi_inline_vecs;
nr_iovecs = BIO_INLINE_VECS;
} else {
bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
if (unlikely(!bvl))
goto err_free;
nr_iovecs = bvec_nr_vecs(idx);
}
out_set:
bio->bi_flags |= idx << BIO_POOL_OFFSET;
bio->bi_max_vecs = nr_iovecs;
bio->bi_io_vec = bvl;
return bio;
err_free:
mempool_free(p, bs->bio_pool);
return NULL;
}
EXPORT_SYMBOL(bio_alloc_bioset);
static void bio_fs_destructor(struct bio *bio)
{
bio_free(bio, fs_bio_set);
}
/**
* bio_alloc - allocate a new bio, memory pool backed
* @gfp_mask: allocation mask to use
* @nr_iovecs: number of iovecs
*
* bio_alloc will allocate a bio and associated bio_vec array that can hold
* at least @nr_iovecs entries. Allocations will be done from the
* fs_bio_set. Also see @bio_alloc_bioset and @bio_kmalloc.
*
* If %__GFP_WAIT is set, then bio_alloc will always be able to allocate
* a bio. This is due to the mempool guarantees. To make this work, callers
* must never allocate more than 1 bio at a time from this pool. Callers
* that need to allocate more than 1 bio must always submit the previously
* allocated bio for IO before attempting to allocate a new one. Failure to
* do so can cause livelocks under memory pressure.
*
* RETURNS:
* Pointer to new bio on success, NULL on failure.
*/
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;
}
EXPORT_SYMBOL(bio_alloc);
static void bio_kmalloc_destructor(struct bio *bio)
{
if (bio_integrity(bio))
bio_integrity_free(bio, fs_bio_set);
kfree(bio);
}
/**
* bio_kmalloc - allocate a bio for I/O using kmalloc()
* @gfp_mask: the GFP_ mask given to the slab allocator
* @nr_iovecs: number of iovecs to pre-allocate
*
* Description:
* Allocate a new bio with @nr_iovecs bvecs. If @gfp_mask contains
* %__GFP_WAIT, the allocation is guaranteed to succeed.
*
**/
struct bio *bio_kmalloc(gfp_t gfp_mask, int nr_iovecs)
{
struct bio *bio;
bio = kmalloc(sizeof(struct bio) + nr_iovecs * sizeof(struct bio_vec),
gfp_mask);
if (unlikely(!bio))
return NULL;
bio_init(bio);
bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET;
bio->bi_max_vecs = nr_iovecs;
bio->bi_io_vec = bio->bi_inline_vecs;
bio->bi_destructor = bio_kmalloc_destructor;
return bio;
}
EXPORT_SYMBOL(bio_kmalloc);
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, bio_get or bio_clone. 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);
}
}
EXPORT_SYMBOL(bio_put);
inline int bio_phys_segments(struct request_queue *q, struct bio *bio)
{
if (unlikely(!bio_flagged(bio, BIO_SEG_VALID)))
blk_recount_segments(q, bio);
return bio->bi_phys_segments;
}
EXPORT_SYMBOL(bio_phys_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)
{
memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
bio_src->bi_max_vecs * sizeof(struct bio_vec));
/*
* most users will be overriding ->bi_bdev with a new target,
* so we don't set nor calculate new physical/hw segment counts here
*/
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;
}
EXPORT_SYMBOL(__bio_clone);
/**
* 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)
return NULL;
b->bi_destructor = bio_fs_destructor;
__bio_clone(b, bio);
if (bio_integrity(bio)) {
int ret;
ret = bio_integrity_clone(b, bio, gfp_mask, fs_bio_set);
if (ret < 0) {
bio_put(b);
return NULL;
}
}
return b;
}
EXPORT_SYMBOL(bio_clone);
/**
* 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)
{
struct request_queue *q = bdev_get_queue(bdev);
int nr_pages;
nr_pages = ((queue_max_sectors(q) << 9) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (nr_pages > queue_max_segments(q))
nr_pages = queue_max_segments(q);
return nr_pages;
}
EXPORT_SYMBOL(bio_get_nr_vecs);
static int __bio_add_page(struct request_queue *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) {
unsigned int prev_bv_len = prev->bv_len;
prev->bv_len += len;
if (q->merge_bvec_fn) {
struct bvec_merge_data bvm = {
/* prev_bvec is already charged in
bi_size, discharge it in order to
simulate merging updated prev_bvec
as new bvec. */
.bi_bdev = bio->bi_bdev,
.bi_sector = bio->bi_sector,
.bi_size = bio->bi_size - prev_bv_len,
.bi_rw = bio->bi_rw,
};
if (q->merge_bvec_fn(q, &bvm, prev) != prev->bv_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 >= queue_max_segments(q)) {
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) {
struct bvec_merge_data bvm = {
.bi_bdev = bio->bi_bdev,
.bi_sector = bio->bi_sector,
.bi_size = bio->bi_size,
.bi_rw = bio->bi_rw,
};
/*
* merge_bvec_fn() returns number of bytes it can accept
* at this offset
*/
if (q->merge_bvec_fn(q, &bvm, bvec) != bvec->bv_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)))
bio->bi_flags &= ~(1 << BIO_SEG_VALID);
bio->bi_vcnt++;
bio->bi_phys_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(struct request_queue *q, struct bio *bio, struct page *page,
unsigned int len, unsigned int offset)
{
return __bio_add_page(q, bio, page, len, offset,
queue_max_hw_sectors(q));
}
EXPORT_SYMBOL(bio_add_pc_page);
/**
* 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, queue_max_sectors(q));
}
EXPORT_SYMBOL(bio_add_page);
struct bio_map_data {
struct bio_vec *iovecs;
struct sg_iovec *sgvecs;
int nr_sgvecs;
int is_our_pages;
};
static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
struct sg_iovec *iov, int iov_count,
int is_our_pages)
{
memcpy(bmd->iovecs, bio->bi_io_vec, sizeof(struct bio_vec) * bio->bi_vcnt);
memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
bmd->nr_sgvecs = iov_count;
bmd->is_our_pages = is_our_pages;
bio->bi_private = bmd;
}
static void bio_free_map_data(struct bio_map_data *bmd)
{
kfree(bmd->iovecs);
kfree(bmd->sgvecs);
kfree(bmd);
}
static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
gfp_t gfp_mask)
{
struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);
if (!bmd)
return NULL;
bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, gfp_mask);
if (!bmd->iovecs) {
kfree(bmd);
return NULL;
}
bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);
if (bmd->sgvecs)
return bmd;
kfree(bmd->iovecs);
kfree(bmd);
return NULL;
}
static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
struct sg_iovec *iov, int iov_count,
int to_user, int from_user, int do_free_page)
{
int ret = 0, i;
struct bio_vec *bvec;
int iov_idx = 0;
unsigned int iov_off = 0;
__bio_for_each_segment(bvec, bio, i, 0) {
char *bv_addr = page_address(bvec->bv_page);
unsigned int bv_len = iovecs[i].bv_len;
while (bv_len && iov_idx < iov_count) {
unsigned int bytes;
char __user *iov_addr;
bytes = min_t(unsigned int,
iov[iov_idx].iov_len - iov_off, bv_len);
iov_addr = iov[iov_idx].iov_base + iov_off;
if (!ret) {
if (to_user)
ret = copy_to_user(iov_addr, bv_addr,
bytes);
if (from_user)
ret = copy_from_user(bv_addr, iov_addr,
bytes);
if (ret)
ret = -EFAULT;
}
bv_len -= bytes;
bv_addr += bytes;
iov_addr += bytes;
iov_off += bytes;
if (iov[iov_idx].iov_len == iov_off) {
iov_idx++;
iov_off = 0;
}
}
if (do_free_page)
__free_page(bvec->bv_page);
}
return ret;
}
/**
* 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;
int ret = 0;
if (!bio_flagged(bio, BIO_NULL_MAPPED))
ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
bmd->nr_sgvecs, bio_data_dir(bio) == READ,
0, bmd->is_our_pages);
bio_free_map_data(bmd);
bio_put(bio);
return ret;
}
EXPORT_SYMBOL(bio_uncopy_user);
/**
* bio_copy_user_iov - copy user data to bio
* @q: destination block queue
* @map_data: pointer to the rq_map_data holding pages (if necessary)
* @iov: the iovec.
* @iov_count: number of elements in the iovec
* @write_to_vm: bool indicating writing to pages or not
* @gfp_mask: memory allocation flags
*
* 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_iov(struct request_queue *q,
struct rq_map_data *map_data,
struct sg_iovec *iov, int iov_count,
int write_to_vm, gfp_t gfp_mask)
{
struct bio_map_data *bmd;
struct bio_vec *bvec;
struct page *page;
struct bio *bio;
int i, ret;
int nr_pages = 0;
unsigned int len = 0;
unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
for (i = 0; i < iov_count; i++) {
unsigned long uaddr;
unsigned long end;
unsigned long start;
uaddr = (unsigned long)iov[i].iov_base;
end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
start = uaddr >> PAGE_SHIFT;
nr_pages += end - start;
len += iov[i].iov_len;
}
if (offset)
nr_pages++;
bmd = bio_alloc_map_data(nr_pages, iov_count, gfp_mask);
if (!bmd)
return ERR_PTR(-ENOMEM);
ret = -ENOMEM;
bio = bio_kmalloc(gfp_mask, nr_pages);
if (!bio)
goto out_bmd;
bio->bi_rw |= (!write_to_vm << BIO_RW);
ret = 0;
if (map_data) {
nr_pages = 1 << map_data->page_order;
i = map_data->offset / PAGE_SIZE;
}
while (len) {
unsigned int bytes = PAGE_SIZE;
bytes -= offset;
if (bytes > len)
bytes = len;
if (map_data) {
if (i == map_data->nr_entries * nr_pages) {
ret = -ENOMEM;
break;
}
page = map_data->pages[i / nr_pages];
page += (i % nr_pages);
i++;
} else {
page = alloc_page(q->bounce_gfp | gfp_mask);
if (!page) {
ret = -ENOMEM;
break;
}
}
if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
break;
len -= bytes;
offset = 0;
}
if (ret)
goto cleanup;
/*
* success
*/
if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
(map_data && map_data->from_user)) {
ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 1, 0);
if (ret)
goto cleanup;
}
bio_set_map_data(bmd, bio, iov, iov_count, map_data ? 0 : 1);
return bio;
cleanup:
if (!map_data)
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);
}
/**
* bio_copy_user - copy user data to bio
* @q: destination block queue
* @map_data: pointer to the rq_map_data holding pages (if necessary)
* @uaddr: start of user address
* @len: length in bytes
* @write_to_vm: bool indicating writing to pages or not
* @gfp_mask: memory allocation flags
*
* 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(struct request_queue *q, struct rq_map_data *map_data,
unsigned long uaddr, unsigned int len,
int write_to_vm, gfp_t gfp_mask)
{
struct sg_iovec iov;
iov.iov_base = (void __user *)uaddr;
iov.iov_len = len;
return bio_copy_user_iov(q, map_data, &iov, 1, write_to_vm, gfp_mask);
}
EXPORT_SYMBOL(bio_copy_user);
static struct bio *__bio_map_user_iov(struct request_queue *q,
struct block_device *bdev,
struct sg_iovec *iov, int iov_count,
int write_to_vm, gfp_t gfp_mask)
{
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_kmalloc(gfp_mask, nr_pages);
if (!bio)
return ERR_PTR(-ENOMEM);
ret = -ENOMEM;
pages = kcalloc(nr_pages, sizeof(struct page *), gfp_mask);
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;
ret = get_user_pages_fast(uaddr, local_nr_pages,
write_to_vm, &pages[cur_page]);
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 struct request_queue 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
* @gfp_mask: memory allocation flags
*
* 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(struct request_queue *q, struct block_device *bdev,
unsigned long uaddr, unsigned int len, int write_to_vm,
gfp_t gfp_mask)
{
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, gfp_mask);
}
EXPORT_SYMBOL(bio_map_user);
/**
* bio_map_user_iov - map user sg_iovec table into bio
* @q: the struct request_queue 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
* @gfp_mask: memory allocation flags
*
* 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(struct request_queue *q, struct block_device *bdev,
struct sg_iovec *iov, int iov_count,
int write_to_vm, gfp_t gfp_mask)
{
struct bio *bio;
bio = __bio_map_user_iov(q, bdev, iov, iov_count, write_to_vm,
gfp_mask);
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);
}
EXPORT_SYMBOL(bio_unmap_user);
static void bio_map_kern_endio(struct bio *bio, int err)
{
bio_put(bio);
}
static struct bio *__bio_map_kern(struct request_queue *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_kmalloc(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 struct request_queue 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(struct request_queue *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);
}
EXPORT_SYMBOL(bio_map_kern);
static void bio_copy_kern_endio(struct bio *bio, int err)
{
struct bio_vec *bvec;
const int read = bio_data_dir(bio) == READ;
struct bio_map_data *bmd = bio->bi_private;
int i;
char *p = bmd->sgvecs[0].iov_base;
__bio_for_each_segment(bvec, bio, i, 0) {
char *addr = page_address(bvec->bv_page);
int len = bmd->iovecs[i].bv_len;
if (read)
memcpy(p, addr, len);
__free_page(bvec->bv_page);
p += len;
}
bio_free_map_data(bmd);
bio_put(bio);
}
/**
* bio_copy_kern - copy kernel address into bio
* @q: the struct request_queue for the bio
* @data: pointer to buffer to copy
* @len: length in bytes
* @gfp_mask: allocation flags for bio and page allocation
* @reading: data direction is READ
*
* copy the kernel address into a bio suitable for io to a block
* device. Returns an error pointer in case of error.
*/
struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,
gfp_t gfp_mask, int reading)
{
struct bio *bio;
struct bio_vec *bvec;
int i;
bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);
if (IS_ERR(bio))
return bio;
if (!reading) {
void *p = data;
bio_for_each_segment(bvec, bio, i) {
char *addr = page_address(bvec->bv_page);
memcpy(addr, p, bvec->bv_len);
p += bvec->bv_len;
}
}
bio->bi_end_io = bio_copy_kern_endio;
return bio;
}
EXPORT_SYMBOL(bio_copy_kern);
/*
* 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(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);
}
}
#if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
void bio_flush_dcache_pages(struct bio *bi)
{
int i;
struct bio_vec *bvec;
bio_for_each_segment(bvec, bi, i)
flush_dcache_page(bvec->bv_page);
}
EXPORT_SYMBOL(bio_flush_dcache_pages);
#endif
/**
* bio_endio - end I/O on a bio
* @bio: bio
* @error: error, if any
*
* Description:
* bio_endio() will end I/O on the whole bio. bio_endio() is the
* preferred way to end I/O on a bio, it takes care of 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, int error)
{
if (error)
clear_bit(BIO_UPTODATE, &bio->bi_flags);
else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
error = -EIO;
if (bio->bi_end_io)
bio->bi_end_io(bio, error);
}
EXPORT_SYMBOL(bio_endio);
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, bp->error);
mempool_free(bp, bp->bio2.bi_private);
}
}
EXPORT_SYMBOL(bio_pair_release);
static void bio_pair_end_1(struct bio *bi, int err)
{
struct bio_pair *bp = container_of(bi, struct bio_pair, bio1);
if (err)
bp->error = err;
bio_pair_release(bp);
}
static void bio_pair_end_2(struct bio *bi, int err)
{
struct bio_pair *bp = container_of(bi, struct bio_pair, bio2);
if (err)
bp->error = err;
bio_pair_release(bp);
}
/*
* split a bio - only worry about a bio with a single page in its iovec
*/
struct bio_pair *bio_split(struct bio *bi, int first_sectors)
{
struct bio_pair *bp = mempool_alloc(bio_split_pool, GFP_NOIO);
if (!bp)
return bp;
trace_block_split(bdev_get_queue(bi->bi_bdev), 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 = bio_split_pool;
if (bio_integrity(bi))
bio_integrity_split(bi, bp, first_sectors);
return bp;
}
EXPORT_SYMBOL(bio_split);
/**
* bio_sector_offset - Find hardware sector offset in bio
* @bio: bio to inspect
* @index: bio_vec index
* @offset: offset in bv_page
*
* Return the number of hardware sectors between beginning of bio
* and an end point indicated by a bio_vec index and an offset
* within that vector's page.
*/
sector_t bio_sector_offset(struct bio *bio, unsigned short index,
unsigned int offset)
{
unsigned int sector_sz;
struct bio_vec *bv;
sector_t sectors;
int i;
sector_sz = queue_logical_block_size(bio->bi_bdev->bd_disk->queue);
sectors = 0;
if (index >= bio->bi_idx)
index = bio->bi_vcnt - 1;
__bio_for_each_segment(bv, bio, i, 0) {
if (i == index) {
if (offset > bv->bv_offset)
sectors += (offset - bv->bv_offset) / sector_sz;
break;
}
sectors += bv->bv_len / sector_sz;
}
return sectors;
}
EXPORT_SYMBOL(bio_sector_offset);
/*
* 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)
{
struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
if (!bs->bvec_pool)
return -ENOMEM;
return 0;
}
static void biovec_free_pools(struct bio_set *bs)
{
mempool_destroy(bs->bvec_pool);
}
void bioset_free(struct bio_set *bs)
{
if (bs->bio_pool)
mempool_destroy(bs->bio_pool);
bioset_integrity_free(bs);
biovec_free_pools(bs);
bio_put_slab(bs);
kfree(bs);
}
EXPORT_SYMBOL(bioset_free);
/**
* bioset_create - Create a bio_set
* @pool_size: Number of bio and bio_vecs to cache in the mempool
* @front_pad: Number of bytes to allocate in front of the returned bio
*
* Description:
* Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
* to ask for a number of bytes to be allocated in front of the bio.
* Front pad allocation is useful for embedding the bio inside
* another structure, to avoid allocating extra data to go with the bio.
* Note that the bio must be embedded at the END of that structure always,
* or things will break badly.
*/
struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
{
unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
struct bio_set *bs;
bs = kzalloc(sizeof(*bs), GFP_KERNEL);
if (!bs)
return NULL;
bs->front_pad = front_pad;
bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
if (!bs->bio_slab) {
kfree(bs);
return NULL;
}
bs->bio_pool = mempool_create_slab_pool(pool_size, bs->bio_slab);
if (!bs->bio_pool)
goto bad;
if (bioset_integrity_create(bs, pool_size))
goto bad;
if (!biovec_create_pools(bs, pool_size))
return bs;
bad:
bioset_free(bs);
return NULL;
}
EXPORT_SYMBOL(bioset_create);
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;
#ifndef CONFIG_BLK_DEV_INTEGRITY
if (bvs->nr_vecs <= BIO_INLINE_VECS) {
bvs->slab = NULL;
continue;
}
#endif
size = bvs->nr_vecs * sizeof(struct bio_vec);
bvs->slab = kmem_cache_create(bvs->name, size, 0,
SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
}
}
static int __init init_bio(void)
{
bio_slab_max = 2;
bio_slab_nr = 0;
bio_slabs = kzalloc(bio_slab_max * sizeof(struct bio_slab), GFP_KERNEL);
if (!bio_slabs)
panic("bio: can't allocate bios\n");
bio_integrity_init();
biovec_init_slabs();
fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
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);
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