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From:   Christoph Hellwig <hch@lst.de>
To:     Jens Axboe <axboe@kernel.dk>
Cc:     Pavel Begunkov <asml.silence@gmail.com>,
        Mike Snitzer <snitzer@redhat.com>,
        Ryusuke Konishi <konishi.ryusuke@gmail.com>,
        Konstantin Komarov <almaz.alexandrovich@paragon-software.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Md . Haris Iqbal " <haris.iqbal@ionos.com>,
        Jack Wang <jinpu.wang@ionos.com>,
        =?UTF-8?q?Roger=20Pau=20Monn=C3=A9?= <roger.pau@citrix.co>,
        Philipp Reisner <philipp.reisner@linbit.com>,
        Lars Ellenberg <lars.ellenberg@linbit.com>,
        linux-block@vger.kernel.org, dm-devel@redhat.com,
        linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
        linux-nilfs@vger.kernel.org, ntfs3@lists.linux.dev,
        xen-devel@lists.xenproject.org, drbd-dev@lists.linbit.com
Subject: [PATCH 10/19] rnbd-srv: simplify bio mapping in process_rdma
Date:   Tue, 18 Jan 2022 08:19:43 +0100
Message-Id: <20220118071952.1243143-11-hch@lst.de>
In-Reply-To: <20220118071952.1243143-1-hch@lst.de>
References: <20220118071952.1243143-1-hch@lst.de>
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Precedence: bulk

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>
---
 drivers/block/rnbd/rnbd-srv-dev.c | 57 -------------------------------
 drivers/block/rnbd/rnbd-srv-dev.h |  5 ---
 drivers/block/rnbd/rnbd-srv.c     | 20 ++++++++---
 3 files changed, 15 insertions(+), 67 deletions(-)

diff --git a/drivers/block/rnbd/rnbd-srv-dev.c b/drivers/block/rnbd/rnbd-srv-dev.c
index b241a099aeae2..98d3e591a0885 100644
--- a/drivers/block/rnbd/rnbd-srv-dev.c
+++ b/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;
-}
diff --git a/drivers/block/rnbd/rnbd-srv-dev.h b/drivers/block/rnbd/rnbd-srv-dev.h
index 0eb23850afb95..1a14ece0be726 100644
--- a/drivers/block/rnbd/rnbd-srv-dev.h
+++ b/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));
diff --git a/drivers/block/rnbd/rnbd-srv.c b/drivers/block/rnbd/rnbd-srv.c
index 1ee808fc600cf..65c670e96075b 100644
--- a/drivers/block/rnbd/rnbd-srv.c
+++ b/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)
@@ -144,11 +152,11 @@ 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);
+	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))) {
+		rnbd_srv_err(sess_dev, "Failed to map data to bio\n");
+		err = -EINVAL;
 		goto sess_dev_put;
 	}
 
@@ -170,6 +178,8 @@ static int process_rdma(struct rnbd_srv_session *srv_sess,
 
 	return 0;
 
+bio_put:
+	bio_put(bio);
 sess_dev_put:
 	rnbd_put_sess_dev(sess_dev);
 err:
-- 
2.30.2