rnbd-srv: simplify bio mapping in process_rdma

The memory mapped in process_rdma is contiguous, so there is no need
to loop over bio_add_page.  Remove rnbd_bio_map_kern and just open code
the bio allocation and mapping in the caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jack Wang <jinpu.wang@ionons.com>
Tested-by: Jack Wang <jinpu.wang@ionos.com>
Link: https://lore.kernel.org/r/20220124091107.642561-11-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/rnbd/rnbd-srv-dev.c

@@ -44,60 +44,3 @@ void rnbd_dev_close(struct rnbd_dev *dev)
 	blkdev_put(dev->bdev, dev->blk_open_flags);
 	kfree(dev);
 }
-
-void rnbd_dev_bi_end_io(struct bio *bio)
-{
-	struct rnbd_dev_blk_io *io = bio->bi_private;
-
-	rnbd_endio(io->priv, blk_status_to_errno(bio->bi_status));
-	bio_put(bio);
-}
-
-/**
- *	rnbd_bio_map_kern	-	map kernel address into bio
- *	@data: pointer to buffer to map
- *	@bs: bio_set to use.
- *	@len: length in bytes
- *	@gfp_mask: allocation flags for bio allocation
- *
- *	Map the kernel address into a bio suitable for io to a block
- *	device. Returns an error pointer in case of error.
- */
-struct bio *rnbd_bio_map_kern(void *data, struct bio_set *bs,
-			      unsigned int len, gfp_t gfp_mask)
-{
-	unsigned long kaddr = (unsigned long)data;
-	unsigned long end = (kaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
-	unsigned long start = kaddr >> PAGE_SHIFT;
-	const int nr_pages = end - start;
-	int offset, i;
-	struct bio *bio;
-
-	bio = bio_alloc_bioset(gfp_mask, nr_pages, bs);
-	if (!bio)
-		return ERR_PTR(-ENOMEM);
-
-	offset = offset_in_page(kaddr);
-	for (i = 0; i < nr_pages; i++) {
-		unsigned int bytes = PAGE_SIZE - offset;
-
-		if (len <= 0)
-			break;
-
-		if (bytes > len)
-			bytes = len;
-
-		if (bio_add_page(bio, virt_to_page(data), bytes,
-				    offset) < bytes) {
-			/* we don't support partial mappings */
-			bio_put(bio);
-			return ERR_PTR(-EINVAL);
-		}
-
-		data += bytes;
-		len -= bytes;
-		offset = 0;
-	}
-
-	return bio;
-}

drivers/block/rnbd/rnbd-srv-dev.h

@@ -41,11 +41,6 @@ void rnbd_dev_close(struct rnbd_dev *dev);
 
 void rnbd_endio(void *priv, int error);
 
-void rnbd_dev_bi_end_io(struct bio *bio);
-
-struct bio *rnbd_bio_map_kern(void *data, struct bio_set *bs,
-			      unsigned int len, gfp_t gfp_mask);
-
 static inline int rnbd_dev_get_max_segs(const struct rnbd_dev *dev)
 {
 	return queue_max_segments(bdev_get_queue(dev->bdev));

drivers/block/rnbd/rnbd-srv.c

@@ -114,6 +114,14 @@ rnbd_get_sess_dev(int dev_id, struct rnbd_srv_session *srv_sess)
 	return sess_dev;
 }
 
+static void rnbd_dev_bi_end_io(struct bio *bio)
+{
+	struct rnbd_dev_blk_io *io = bio->bi_private;
+
+	rnbd_endio(io->priv, blk_status_to_errno(bio->bi_status));
+	bio_put(bio);
+}
+
 static int process_rdma(struct rnbd_srv_session *srv_sess,
 			struct rtrs_srv_op *id, void *data, u32 datalen,
 			const void *usr, size_t usrlen)
@@ -144,12 +152,12 @@ static int process_rdma(struct rnbd_srv_session *srv_sess,
 	priv->sess_dev = sess_dev;
 	priv->id = id;
 
-	/* Generate bio with pages pointing to the rdma buffer */
-	bio = rnbd_bio_map_kern(data, sess_dev->rnbd_dev->ibd_bio_set, datalen, GFP_KERNEL);
-	if (IS_ERR(bio)) {
-		err = PTR_ERR(bio);
-		rnbd_srv_err(sess_dev, "Failed to generate bio, err: %d\n", err);
-		goto sess_dev_put;
+	bio = bio_alloc_bioset(GFP_KERNEL, 1, sess_dev->rnbd_dev->ibd_bio_set);
+	if (bio_add_page(bio, virt_to_page(data), datalen,
+			offset_in_page(data)) != datalen) {
+		rnbd_srv_err(sess_dev, "Failed to map data to bio\n");
+		err = -EINVAL;
+		goto bio_put;
 	}
 
 	io = container_of(bio, struct rnbd_dev_blk_io, bio);
@@ -170,7 +178,8 @@ static int process_rdma(struct rnbd_srv_session *srv_sess,
 
 	return 0;
 
-sess_dev_put:
+bio_put:
+	bio_put(bio);
 	rnbd_put_sess_dev(sess_dev);
 err:
 	kfree(priv);