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Commit 42d2683a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: simplify bio_map_kern 



Just open code the trivial mapping from a kernel virtual address to
a bio instead of going through the complex user address mapping
machinery.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent ad9cf3bb

block/bio.c

+44 −16
Original line number Diff line number Diff line
@@ -1563,9 +1563,8 @@ 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;

	char *p = bio->bi_private;

	int i;

	char *p = bmd->sgvecs[0].iov_base;



	bio_for_each_segment_all(bvec, bio, i) {

		char *addr = page_address(bvec->bv_page);
@@ -1577,7 +1576,6 @@ static void bio_copy_kern_endio(struct bio *bio, int err) 
		p += bvec->bv_len;

	}



	kfree(bmd);

	bio_put(bio);

}
@@ -1595,28 +1593,58 @@ static void bio_copy_kern_endio(struct bio *bio, int err) 
struct bio *bio_copy_kern(struct request_queue *q, void *data, unsigned int len,

			  gfp_t gfp_mask, int reading)

{

	struct bio *bio;

	unsigned long kaddr = (unsigned long)data;

	unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;

	unsigned long start = kaddr >> PAGE_SHIFT;

	struct bio_vec *bvec;

	int i;

	struct bio *bio;

	void *p = data;

	int nr_pages = 0, i;



	bio = bio_copy_user(q, NULL, (unsigned long)data, len, 1, gfp_mask);

	if (IS_ERR(bio))

		return bio;

	/*

	 * Overflow, abort

	 */

	if (end < start)

		return ERR_PTR(-EINVAL);



	if (!reading) {

		void *p = data;

	nr_pages = end - start;

	bio = bio_kmalloc(gfp_mask, nr_pages);

	if (!bio)

		return ERR_PTR(-ENOMEM);



		bio_for_each_segment_all(bvec, bio, i) {

			char *addr = page_address(bvec->bv_page);

	while (len) {

		struct page *page;

		unsigned int bytes = PAGE_SIZE;



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

			p += bvec->bv_len;

		}

		if (bytes > len)

			bytes = len;



		page = alloc_page(q->bounce_gfp | gfp_mask);

		if (!page)

			goto cleanup;



		if (!reading)

			memcpy(page_address(page), p, bytes);



		if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)

			break;



		len -= bytes;

		p += bytes;

	}



	bio->bi_end_io = bio_copy_kern_endio;

	if (!reading)

		bio->bi_rw |= REQ_WRITE;



	bio->bi_private = data;

	bio->bi_end_io = bio_copy_kern_endio;

	return bio;



cleanup:

	bio_for_each_segment_all(bvec, bio, i)

		__free_page(bvec->bv_page);

	bio_put(bio);

	return ERR_PTR(-ENOMEM);

}

EXPORT_SYMBOL(bio_copy_kern);