Commit 451a9ebf authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

bio: fix bio_kmalloc() 



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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent cd0aca2d

fs/bio.c

+54 −64
Original line number Diff line number Diff line
@@ -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;

	if (unlikely(!p))

		return NULL;

	bio = p + bs->front_pad;

	} else {

		bio = kmalloc(sizeof(*bio), gfp_mask);

		if (!bio)

			goto err;

	}



	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:

	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
@@ -366,28 +365,19 @@ 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 = 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;

include/linux/bio.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

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