From 37987547932c89f15f9b76950040131ddb591a8b Mon Sep 17 00:00:00 2001 From: Kanchan Joshi Date: Fri, 30 Sep 2022 11:57:47 +0530 Subject: 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: Kanchan Joshi Signed-off-by: Anuj Gupta Suggested-by: Christoph Hellwig Link: https://lore.kernel.org/r/20220930062749.152261-11-anuj20.g@samsung.com Signed-off-by: Jens Axboe --- block/blk-map.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 71 insertions(+), 4 deletions(-) (limited to 'block/blk-map.c') diff --git a/block/blk-map.c b/block/blk-map.c index d6ea377394a9..34735626b00f 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -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) -- cgit v1.2.3