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bio: fix bio_kmalloc()

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Impact: fix bio_kmalloc() and its destruction path

bio_kmalloc() was broken in two ways.

* bvec_alloc_bs() first allocates bvec using kmalloc() and then
  ignores it and allocates again like non-kmalloc bvecs.

* bio_kmalloc_destructor() didn't check for and free bio integrity
  data.

This patch fixes the above problems.  kmalloc patch is separated out
from bio_alloc_bioset() and allocates the requested number of bvecs as
inline bvecs.

* bio_alloc_bioset() no longer takes NULL @bs.  None other than
  bio_kmalloc() used it and outside users can't know how it was
  allocated anyway.

* Define and use BIO_POOL_NONE so that pool index check in
  bvec_free_bs() triggers if inline or kmalloc allocated bvec gets
  there.

* Relocate destructors on top of each allocation function so that how
  they're used is more clear.

Jens Axboe suggested allocating bvecs inline.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Tejun Heo 2009-04-15 19:50:51 +02:00 committed by Jens Axboe
parent cd0aca2d55
commit 451a9ebf65
2 changed files with 54 additions and 63 deletions
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116
fs/bio.c
View File

@ -174,14 +174,6 @@ struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
{
struct bio_vec *bvl;
/*
* If 'bs' is given, lookup the pool and do the mempool alloc.
* If not, this is a bio_kmalloc() allocation and just do a
* kzalloc() for the exact number of vecs right away.
*/
if (!bs)
bvl = kmalloc(nr * sizeof(struct bio_vec), gfp_mask);
/*
* see comment near bvec_array define!
*/
@ -260,21 +252,6 @@ void bio_free(struct bio *bio, struct bio_set *bs)
mempool_free(p, bs->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);
}
static void bio_kmalloc_destructor(struct bio *bio)
{
if (bio_has_allocated_vec(bio))
kfree(bio->bi_io_vec);
kfree(bio);
}
void bio_init(struct bio *bio)
{
memset(bio, 0, sizeof(*bio));
@ -301,21 +278,15 @@ void bio_init(struct bio *bio)
**/
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 = NULL;
unsigned long idx = 0;
void *p = NULL;
struct bio *bio;
void *p;
if (bs) {
p = mempool_alloc(bs->bio_pool, gfp_mask);
if (!p)
goto err;
bio = p + bs->front_pad;
} else {
bio = kmalloc(sizeof(*bio), gfp_mask);
if (!bio)
goto err;
}
p = mempool_alloc(bs->bio_pool, gfp_mask);
if (unlikely(!p))
return NULL;
bio = p + bs->front_pad;
bio_init(bio);
@ -332,22 +303,50 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
nr_iovecs = bvec_nr_vecs(idx);
}
out_set:
bio->bi_flags |= idx << BIO_POOL_OFFSET;
bio->bi_max_vecs = nr_iovecs;
out_set:
bio->bi_io_vec = bvl;
return bio;
err_free:
if (bs)
mempool_free(p, bs->bio_pool);
else
kfree(bio);
err:
mempool_free(p, bs->bio_pool);
return NULL;
}
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
*
* Allocate a new bio with @nr_iovecs bvecs. If @gfp_mask
* contains __GFP_WAIT, the allocation is guaranteed to succeed.
*
* 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;
}
static void bio_kmalloc_destructor(struct bio *bio)
{
if (bio_integrity(bio))
bio_integrity_free(bio);
kfree(bio);
}
/**
* bio_alloc - allocate a bio for I/O
* @gfp_mask: the GFP_ mask given to the slab allocator
@ -366,29 +365,20 @@ err:
* do so can cause livelocks under memory pressure.
*
**/
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;
}
/*
* Like bio_alloc(), but doesn't use a mempool backing. This means that
* it CAN fail, but while bio_alloc() can only be used for allocations
* that have a short (finite) life span, bio_kmalloc() should be used
* for more permanent bio allocations (like allocating some bio's for
* initalization or setup purposes).
*/
struct bio *bio_kmalloc(gfp_t gfp_mask, int nr_iovecs)
{
struct bio *bio = bio_alloc_bioset(gfp_mask, nr_iovecs, NULL);
struct bio *bio;
if (bio)
bio->bi_destructor = bio_kmalloc_destructor;
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;
}

1
include/linux/bio.h
View File

@ -132,6 +132,7 @@ struct bio {
* top 4 bits of bio flags indicate the pool this bio came from
*/
#define BIO_POOL_BITS (4)
#define BIO_POOL_NONE ((1UL << BIO_POOL_BITS) - 1)
#define BIO_POOL_OFFSET (BITS_PER_LONG - BIO_POOL_BITS)
#define BIO_POOL_MASK (1UL << BIO_POOL_OFFSET)
#define BIO_POOL_IDX(bio) ((bio)->bi_flags >> BIO_POOL_OFFSET)