Commit 37987547 authored by Kanchan Joshi's avatar Kanchan Joshi Committed by Jens Axboe
Browse files

block: extend functionality to map bvec iterator 



Extend blk_rq_map_user_iov so that it can handle bvec iterator, using
the new blk_rq_map_user_bvec function. It maps the pages from bvec
iterator into a bio and place the bio into request.

This helper will be used by nvme for uring-passthrough path when IO is
done using pre-mapped buffers.

Signed-off-by: default avatarKanchan Joshi <joshi.k@samsung.com>
Signed-off-by: default avatarAnuj Gupta <anuj20.g@samsung.com>
Suggested-by: default avatarChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220930062749.152261-11-anuj20.g@samsung.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent ab89e8e7

block/blk-map.c

+71 −4
Original line number Diff line number Diff line
@@ -548,6 +548,62 @@ int blk_rq_append_bio(struct request *rq, struct bio *bio) 
}

EXPORT_SYMBOL(blk_rq_append_bio);



/* Prepare bio for passthrough IO given ITER_BVEC iter */

static int blk_rq_map_user_bvec(struct request *rq, const struct iov_iter *iter)

{

	struct request_queue *q = rq->q;

	size_t nr_iter = iov_iter_count(iter);

	size_t nr_segs = iter->nr_segs;

	struct bio_vec *bvecs, *bvprvp = NULL;

	struct queue_limits *lim = &q->limits;

	unsigned int nsegs = 0, bytes = 0;

	struct bio *bio;

	size_t i;



	if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q))

		return -EINVAL;

	if (nr_segs > queue_max_segments(q))

		return -EINVAL;



	/* no iovecs to alloc, as we already have a BVEC iterator */

	bio = blk_rq_map_bio_alloc(rq, 0, GFP_KERNEL);

	if (bio == NULL)

		return -ENOMEM;



	bio_iov_bvec_set(bio, (struct iov_iter *)iter);

	blk_rq_bio_prep(rq, bio, nr_segs);



	/* loop to perform a bunch of sanity checks */

	bvecs = (struct bio_vec *)iter->bvec;

	for (i = 0; i < nr_segs; i++) {

		struct bio_vec *bv = &bvecs[i];



		/*

		 * If the queue doesn't support SG gaps and adding this

		 * offset would create a gap, fallback to copy.

		 */

		if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset)) {

			blk_mq_map_bio_put(bio);

			return -EREMOTEIO;

		}

		/* check full condition */

		if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len)

			goto put_bio;

		if (bytes + bv->bv_len > nr_iter)

			goto put_bio;

		if (bv->bv_offset + bv->bv_len > PAGE_SIZE)

			goto put_bio;



		nsegs++;

		bytes += bv->bv_len;

		bvprvp = bv;

	}

	return 0;

put_bio:

	blk_mq_map_bio_put(bio);

	return -EINVAL;

}



/**

 * blk_rq_map_user_iov - map user data to a request, for passthrough requests

 * @q:		request queue where request should be inserted
@@ -567,24 +623,35 @@ 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)

{

	bool copy = false;

	bool copy = false, map_bvec = false;

	unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);

	struct bio *bio = NULL;

	struct iov_iter i;

	int ret = -EINVAL;



	if (!iter_is_iovec(iter))

		goto fail;



	if (map_data)

		copy = true;

	else if (blk_queue_may_bounce(q))

		copy = true;

	else if (iov_iter_alignment(iter) & align)

		copy = true;

	else if (iov_iter_is_bvec(iter))

		map_bvec = true;

	else if (!iter_is_iovec(iter))

		copy = true;

	else if (queue_virt_boundary(q))

		copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);



	if (map_bvec) {

		ret = blk_rq_map_user_bvec(rq, iter);

		if (!ret)

			return 0;

		if (ret != -EREMOTEIO)

			goto fail;

		/* fall back to copying the data on limits mismatches */

		copy = true;

	}



	i = *iter;

	do {

		if (copy)