Add blk_rq_map_user_bvec which maps the pages from bvec iterator into a
bio, and places the bio into the request. This helper will be used by
nvme for uring-passthrough path with pre-mapped buffers.
Signed-off-by: Kanchan Joshi <joshi.k@xxxxxxxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
---
block/blk-map.c | 80 ++++++++++++++++++++++++++++++++++++++++++
include/linux/blk-mq.h | 1 +
2 files changed, 81 insertions(+)
diff --git a/block/blk-map.c b/block/blk-map.c
index a7838879e28e..d6265d49b15b 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -622,6 +622,86 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
}
EXPORT_SYMBOL(blk_rq_map_user);
+/* Prepare bio for passthrough IO given an existing bvec iter */
+int blk_rq_map_user_bvec(struct request *rq, struct iov_iter *iter)
+{
+ struct request_queue *q = rq->q;
+ size_t nr_iter, nr_segs, i;
+ struct bio *bio = NULL;
+ struct bio_vec *bv, *bvecs, *bvprvp = NULL;
+ struct queue_limits *lim = &q->limits;
+ unsigned int nsegs = 0, bytes = 0;
+ bool copy = false;
+ int ret;
+ unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
+
+ /* see if we need to copy pages due to any weird situation */
+ if (blk_queue_may_bounce(q))
+ copy = true;
+ else if (iov_iter_alignment(iter) & align)
+ copy = true;
+
+ if (copy) {
+ do {
+ ret = bio_copy_user_iov(rq, NULL, iter, GFP_KERNEL);
+ if (ret) {
+ blk_rq_unmap_user(bio);
+ rq->bio = NULL;
+ break;
+ }
+ if (!bio)
+ bio = rq->bio;
+ } while (iov_iter_count(iter));
+
+ return ret;
+ }
+ /* common (non-copy) case handling */
+ nr_iter = iov_iter_count(iter);
+ nr_segs = iter->nr_segs;
+
+ 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 = bio_map_get(rq, 0, GFP_KERNEL);
+ if (bio == NULL)
+ return -ENOMEM;
+
+ bio_iov_bvec_set(bio, 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++) {
+ bv = &bvecs[i];
+ /*
+ * If the queue doesn't support SG gaps and adding this
+ * offset would create a gap, disallow it.
+ */
+ if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset))
+ goto put_bio;
+
+ /* 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:
+ bio_map_put(bio);
+ return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(blk_rq_map_user_bvec);
+
/**
* blk_rq_unmap_user - unmap a request with user data
* @bio: start of bio list
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 00a15808c137..1a9ae17e49be 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -977,6 +977,7 @@ struct rq_map_data {
bool from_user;
};
+int blk_rq_map_user_bvec(struct request *rq, struct iov_iter *iter);
int blk_rq_map_user(struct request_queue *, struct request *,
struct rq_map_data *, void __user *, unsigned long, gfp_t);
int blk_rq_map_user_iov(struct request_queue *, struct request *,
--
2.25.1
