block/rnbd: server: functionality for IO submitting to block dev

This provides helper functions for IO submitting to block dev.

Link: https://lore.kernel.org/r/20200511135131.27580-22-danil.kipnis@cloud.ionos.comSigned-off-by: Danil Kipnis <danil.kipnis@cloud.ionos.com>
Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

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

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RDMA Network Block Driver
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
+ */
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include "rnbd-srv-dev.h"
+#include "rnbd-log.h"
+
+struct rnbd_dev *rnbd_dev_open(const char *path, fmode_t flags,
+			       struct bio_set *bs)
+{
+	struct rnbd_dev *dev;
+	int ret;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	dev->blk_open_flags = flags;
+	dev->bdev = blkdev_get_by_path(path, flags, THIS_MODULE);
+	ret = PTR_ERR_OR_ZERO(dev->bdev);
+	if (ret)
+		goto err;
+
+	dev->blk_open_flags = flags;
+	bdevname(dev->bdev, dev->name);
+	dev->ibd_bio_set = bs;
+
+	return dev;
+
+err:
+	kfree(dev);
+	return ERR_PTR(ret);
+}
+
+void rnbd_dev_close(struct rnbd_dev *dev)
+{
+	blkdev_put(dev->bdev, dev->blk_open_flags);
+	kfree(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);
+}
+
+/**
+ *	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.
+ */
+static 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;
+	}
+
+	bio->bi_end_io = bio_put;
+	return bio;
+}
+
+int rnbd_dev_submit_io(struct rnbd_dev *dev, sector_t sector, void *data,
+		       size_t len, u32 bi_size, enum rnbd_io_flags flags,
+		       short prio, void *priv)
+{
+	struct rnbd_dev_blk_io *io;
+	struct bio *bio;
+
+	/* Generate bio with pages pointing to the rdma buffer */
+	bio = rnbd_bio_map_kern(data, dev->ibd_bio_set, len, GFP_KERNEL);
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	io = container_of(bio, struct rnbd_dev_blk_io, bio);
+
+	io->dev	= dev;
+	io->priv = priv;
+
+	bio->bi_end_io = rnbd_dev_bi_end_io;
+	bio->bi_private	= io;
+	bio->bi_opf = rnbd_to_bio_flags(flags);
+	bio->bi_iter.bi_sector = sector;
+	bio->bi_iter.bi_size = bi_size;
+	bio_set_prio(bio, prio);
+	bio_set_dev(bio, dev->bdev);
+
+	submit_bio(bio);
+
+	return 0;
+}

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

+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * RDMA Network Block Driver
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
+ */
+#ifndef RNBD_SRV_DEV_H
+#define RNBD_SRV_DEV_H
+
+#include <linux/fs.h>
+#include "rnbd-proto.h"
+
+struct rnbd_dev {
+	struct block_device	*bdev;
+	struct bio_set		*ibd_bio_set;
+	fmode_t			blk_open_flags;
+	char			name[BDEVNAME_SIZE];
+};
+
+struct rnbd_dev_blk_io {
+	struct rnbd_dev *dev;
+	void		 *priv;
+	/* have to be last member for front_pad usage of bioset_init */
+	struct bio	bio;
+};
+
+/**
+ * rnbd_dev_open() - Open a device
+ * @flags:	open flags
+ * @bs:		bio_set to use during block io,
+ */
+struct rnbd_dev *rnbd_dev_open(const char *path, fmode_t flags,
+			       struct bio_set *bs);
+
+/**
+ * rnbd_dev_close() - Close a device
+ */
+void rnbd_dev_close(struct rnbd_dev *dev);
+
+void rnbd_endio(void *priv, int error);
+
+static inline int rnbd_dev_get_max_segs(const struct rnbd_dev *dev)
+{
+	return queue_max_segments(bdev_get_queue(dev->bdev));
+}
+
+static inline int rnbd_dev_get_max_hw_sects(const struct rnbd_dev *dev)
+{
+	return queue_max_hw_sectors(bdev_get_queue(dev->bdev));
+}
+
+static inline int rnbd_dev_get_secure_discard(const struct rnbd_dev *dev)
+{
+	return blk_queue_secure_erase(bdev_get_queue(dev->bdev));
+}
+
+static inline int rnbd_dev_get_max_discard_sects(const struct rnbd_dev *dev)
+{
+	if (!blk_queue_discard(bdev_get_queue(dev->bdev)))
+		return 0;
+
+	return blk_queue_get_max_sectors(bdev_get_queue(dev->bdev),
+					 REQ_OP_DISCARD);
+}
+
+static inline int rnbd_dev_get_discard_granularity(const struct rnbd_dev *dev)
+{
+	return bdev_get_queue(dev->bdev)->limits.discard_granularity;
+}
+
+static inline int rnbd_dev_get_discard_alignment(const struct rnbd_dev *dev)
+{
+	return bdev_get_queue(dev->bdev)->limits.discard_alignment;
+}
+
+/**
+ * rnbd_dev_submit_io() - Submit an I/O to the disk
+ * @dev:	device to that the I/O is submitted
+ * @sector:	address to read/write data to
+ * @data:	I/O data to write or buffer to read I/O date into
+ * @len:	length of @data
+ * @bi_size:	Amount of data that will be read/written
+ * @prio:       IO priority
+ * @priv:	private data passed to @io_fn
+ */
+int rnbd_dev_submit_io(struct rnbd_dev *dev, sector_t sector, void *data,
+			size_t len, u32 bi_size, enum rnbd_io_flags flags,
+			short prio, void *priv);
+
+#endif /* RNBD_SRV_DEV_H */