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Commit 4d6af73d authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Jens Axboe
Browse files

block: support large requests in blk_rq_map_user_iov 



This patch adds support for larger requests in blk_rq_map_user_iov by
allowing it to build multiple bios for a request.  This functionality
used to exist for the non-vectored blk_rq_map_user in the past, and
this patch reuses the existing functionality for it on the unmap side,
which stuck around.  Thanks to the iov_iter API supporting multiple
bios is fairly trivial, as we can just iterate the iov until we've
consumed the whole iov_iter.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reported-by: default avatarJeff Lien <Jeff.Lien@hgst.com>
Tested-by: default avatarJeff Lien <Jeff.Lien@hgst.com>
Reviewed-by: default avatarKeith Busch <keith.busch@intel.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent f2101842

block/blk-map.c

+61 −30
Original line number Diff line number Diff line
@@ -57,6 +57,49 @@ static int __blk_rq_unmap_user(struct bio *bio) 
	return ret;

}



static int __blk_rq_map_user_iov(struct request *rq,

		struct rq_map_data *map_data, struct iov_iter *iter,

		gfp_t gfp_mask, bool copy)

{

	struct request_queue *q = rq->q;

	struct bio *bio, *orig_bio;

	int ret;



	if (copy)

		bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);

	else

		bio = bio_map_user_iov(q, iter, gfp_mask);



	if (IS_ERR(bio))

		return PTR_ERR(bio);



	if (map_data && map_data->null_mapped)

		bio_set_flag(bio, BIO_NULL_MAPPED);



	iov_iter_advance(iter, bio->bi_iter.bi_size);

	if (map_data)

		map_data->offset += bio->bi_iter.bi_size;



	orig_bio = bio;

	blk_queue_bounce(q, &bio);



	/*

	 * We link the bounce buffer in and could have to traverse it

	 * later so we have to get a ref to prevent it from being freed

	 */

	bio_get(bio);



	ret = blk_rq_append_bio(q, rq, bio);

	if (ret) {

		bio_endio(bio);

		__blk_rq_unmap_user(orig_bio);

		bio_put(bio);

		return ret;

	}



	return 0;

}



/**

 * blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage

 * @q:		request queue where request should be inserted
@@ -82,10 +125,11 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 
			struct rq_map_data *map_data,

			const struct iov_iter *iter, gfp_t gfp_mask)

{

	struct bio *bio;

	int unaligned = 0;

	struct iov_iter i;

	struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0};

	bool copy = (q->dma_pad_mask & iter->count) || map_data;

	struct bio *bio = NULL;

	struct iov_iter i;

	int ret;



	if (!iter || !iter->count)

		return -EINVAL;
@@ -101,42 +145,29 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq, 
		 */

		if ((uaddr & queue_dma_alignment(q)) ||

		    iovec_gap_to_prv(q, &prv, &iov))

			unaligned = 1;

			copy = true;



		prv.iov_base = iov.iov_base;

		prv.iov_len = iov.iov_len;

	}



	if (unaligned || (q->dma_pad_mask & iter->count) || map_data)

		bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);

	else

		bio = bio_map_user_iov(q, iter, gfp_mask);



	if (IS_ERR(bio))

		return PTR_ERR(bio);



	if (map_data && map_data->null_mapped)

		bio_set_flag(bio, BIO_NULL_MAPPED);



	if (bio->bi_iter.bi_size != iter->count) {

		/*

		 * Grab an extra reference to this bio, as bio_unmap_user()

		 * expects to be able to drop it twice as it happens on the

		 * normal IO completion path

		 */

		bio_get(bio);

		bio_endio(bio);

		__blk_rq_unmap_user(bio);

		return -EINVAL;

	}

	i = *iter;

	do {

		ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);

		if (ret)

			goto unmap_rq;

		if (!bio)

			bio = rq->bio;

	} while (iov_iter_count(&i));



	if (!bio_flagged(bio, BIO_USER_MAPPED))

		rq->cmd_flags |= REQ_COPY_USER;



	blk_queue_bounce(q, &bio);

	bio_get(bio);

	blk_rq_bio_prep(q, rq, bio);

	return 0;



unmap_rq:

	__blk_rq_unmap_user(bio);

	rq->bio = NULL;

	return -EINVAL;

}

EXPORT_SYMBOL(blk_rq_map_user_iov);