Commit 81882766 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Jens Axboe
Browse files

block: make blk_rq_map_user take a NULL user-space buffer 



This patch changes blk_rq_map_user to accept a NULL user-space buffer
with a READ command if rq_map_data is not NULL. Thus a caller can pass
page frames to lk_rq_map_user to just set up a request and bios with
page frames propely. bio_uncopy_user (called via blk_rq_unmap_user)
doesn't copy data to user space with such request.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 839e96af

block/blk-map.c

+12 −4
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ static int __blk_rq_unmap_user(struct bio *bio) 


static int __blk_rq_map_user(struct request_queue *q, struct request *rq,

			     struct rq_map_data *map_data, void __user *ubuf,

			     unsigned int len, gfp_t gfp_mask)

			     unsigned int len, int null_mapped, gfp_t gfp_mask)

{

	unsigned long uaddr;

	struct bio *bio, *orig_bio;
@@ -63,6 +63,9 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, 
	if (IS_ERR(bio))

		return PTR_ERR(bio);



	if (null_mapped)

		bio->bi_flags |= (1 << BIO_NULL_MAPPED);



	orig_bio = bio;

	blk_queue_bounce(q, &bio);
@@ -111,12 +114,17 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq, 
{

	unsigned long bytes_read = 0;

	struct bio *bio = NULL;

	int ret;

	int ret, null_mapped = 0;



	if (len > (q->max_hw_sectors << 9))

		return -EINVAL;

	if (!len || !ubuf)

	if (!len)

		return -EINVAL;

	if (!ubuf) {

		if (!map_data || rq_data_dir(rq) != READ)

			return -EINVAL;

		null_mapped = 1;

	}



	while (bytes_read != len) {

		unsigned long map_len, end, start;
@@ -135,7 +143,7 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq, 
			map_len -= PAGE_SIZE;



		ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len,

					gfp_mask);

					null_mapped, gfp_mask);

		if (ret < 0)

			goto unmap_rq;

		if (!bio)

fs/bio.c

+4 −4
Original line number Diff line number Diff line
@@ -547,11 +547,11 @@ static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs, 
int bio_uncopy_user(struct bio *bio)

{

	struct bio_map_data *bmd = bio->bi_private;

	int ret;



	ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs, bmd->nr_sgvecs, 1,

			     bmd->is_our_pages);

	int ret = 0;



	if (!bio_flagged(bio, BIO_NULL_MAPPED))

		ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,

				     bmd->nr_sgvecs, 1, bmd->is_our_pages);

	bio_free_map_data(bmd);

	bio_put(bio);

	return ret;

include/linux/bio.h

+1 −0
Original line number Diff line number Diff line
@@ -108,6 +108,7 @@ struct bio { 
#define BIO_USER_MAPPED 6	/* contains user pages */

#define BIO_EOPNOTSUPP	7	/* not supported */

#define BIO_CPU_AFFINE	8	/* complete bio on same CPU as submitted */

#define BIO_NULL_MAPPED 9	/* contains invalid user pages */

#define bio_flagged(bio, flag)	((bio)->bi_flags & (1 << (flag)))



/*

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