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linux-next/fs/bio.c
Kent Overstreet 5abebfdd02 bio: don't overflow in bio_get_nr_vecs() 
There were two places bio_get_nr_vecs() could overflow:

First, it did a left shift to convert from sectors to bytes immediately
before dividing by PAGE_SIZE.  If PAGE_SIZE ever was less than 512 a great
many things would break, so dividing by PAGE_SIZE >> 9 is safe and will
generate smaller code too.

The nastier overflow was in the DIV_ROUND_UP() (that's what the code was
effectively doing, anyways).  If n + d overflowed, the whole thing would
return 0 which breaks things rather effectively.

bio_get_nr_vecs() doesn't claim to give an exact value anyways, so the
DIV_ROUND_UP() is silly; we could do a straight divide except if a
device's queue_max_sectors was less than PAGE_SIZE we'd return 0.  So we
just add 1; this should always be safe - things will break badly if
bio_get_nr_vecs() returns > BIO_MAX_PAGES (bio_alloc() will suddenly start
failing) but it's queue_max_segments that must guard against this, if
queue_max_sectors is preventing this from happen things are going to
explode on architectures with different PAGE_SIZE.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-02-08 22:07:18 +01:00

1689 lines
39 KiB
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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) }
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
/*
* 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(KERN_INFO "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;
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.
*
* Description:
* bio_alloc_bioset will 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.
*
* 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, unsigned 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, unsigned int nr_iovecs)
{
struct bio *bio;
if (nr_iovecs > UIO_MAXIOV)
return NULL;
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);
return min_t(unsigned,
queue_max_segments(q),
queue_max_sectors(q) / (PAGE_SIZE >> 9) + 1);
}
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 up to 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 up to 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,
unsigned int iov_count,
gfp_t gfp_mask)
{
struct bio_map_data *bmd;
if (iov_count > UIO_MAXIOV)
return NULL;
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;
/*
* Overflow, abort
*/
if (end < start)
return ERR_PTR(-EINVAL);
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;
if (!write_to_vm)
bio->bi_rw |= REQ_WRITE;
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;
/*
* Overflow, abort
*/
if (end < start)
return ERR_PTR(-EINVAL);
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 |= REQ_WRITE;
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. No one 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 (!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;
if (bvs->nr_vecs <= BIO_INLINE_VECS) {
bvs->slab = NULL;
continue;
}
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");
if (bioset_integrity_create(fs_bio_set, BIO_POOL_SIZE))
panic("bio: can't create integrity pool\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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