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Commit 76029ff3 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Jens Axboe
Browse files

bio: fix bio_copy_kern() handling of bio->bv_len 



The commit 68154e90 introduced
bio_copy_kern() to add bounce support to blk_rq_map_kern.

bio_copy_kern() uses bio->bv_len to copy data for READ commands after
the completion but it doesn't work with a request that partially
completed. SCSI always completes a PC request as a whole but seems
some don't.

This patch fixes bio_copy_kern to handle the above case. As
bio_copy_user does, bio_copy_kern uses struct bio_map_data to store
struct bio_vec.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reported-by: default avatarNix <nix@esperi.org.uk>
Tested-by: default avatarNix <nix@esperi.org.uk>
Cc: stable@kernel.org
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 48fd4f93

fs/bio.c

+28 −10
Original line number Diff line number Diff line
@@ -469,20 +469,21 @@ static void bio_free_map_data(struct bio_map_data *bmd) 
	kfree(bmd);

}



static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count)

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_KERNEL);

	struct bio_map_data *bmd = kmalloc(sizeof(*bmd), gfp_mask);



	if (!bmd)

		return NULL;



	bmd->iovecs = kmalloc(sizeof(struct bio_vec) * nr_segs, GFP_KERNEL);

	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_KERNEL);

	bmd->sgvecs = kmalloc(sizeof(struct sg_iovec) * iov_count, gfp_mask);

	if (bmd->sgvecs)

		return bmd;
@@ -596,7 +597,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q, struct sg_iovec *iov, 
		len += iov[i].iov_len;

	}



	bmd = bio_alloc_map_data(nr_pages, iov_count);

	bmd = bio_alloc_map_data(nr_pages, iov_count, GFP_KERNEL);

	if (!bmd)

		return ERR_PTR(-ENOMEM);
@@ -942,19 +943,22 @@ static void bio_copy_kern_endio(struct bio *bio, int err) 
{

	struct bio_vec *bvec;

	const int read = bio_data_dir(bio) == READ;

	char *p = bio->bi_private;

	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 && !err)

			memcpy(p, addr, bvec->bv_len);

			memcpy(p, addr, len);



		__free_page(bvec->bv_page);

		p += bvec->bv_len;

		p += len;

	}



	bio_free_map_data(bmd);

	bio_put(bio);

}
@@ -978,11 +982,21 @@ struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len, 
	const int nr_pages = end - start;

	struct bio *bio;

	struct bio_vec *bvec;

	struct bio_map_data *bmd;

	int i, ret;

	struct sg_iovec iov;



	iov.iov_base = data;

	iov.iov_len = len;



	bmd = bio_alloc_map_data(nr_pages, 1, gfp_mask);

	if (!bmd)

		return ERR_PTR(-ENOMEM);



	ret = -ENOMEM;

	bio = bio_alloc(gfp_mask, nr_pages);

	if (!bio)

		return ERR_PTR(-ENOMEM);

		goto out_bmd;



	while (len) {

		struct page *page;
@@ -1016,14 +1030,18 @@ struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len, 
		}

	}



	bio->bi_private = data;

	bio->bi_private = bmd;

	bio->bi_end_io = bio_copy_kern_endio;



	bio_set_map_data(bmd, bio, &iov, 1);

	return bio;

cleanup:

	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);

}