ublk: implement integrity user copy

Add a function ublk_copy_user_integrity() to copy integrity information
between a request and a user iov_iter. This mirrors the existing
ublk_copy_user_pages() but operates on request integrity data instead of
regular data. Check UBLKSRV_IO_INTEGRITY_FLAG in iocb->ki_pos in
ublk_user_copy() to choose between copying data or integrity data.

[csander: change offset units from data bytes to integrity data bytes,
 fix CONFIG_BLK_DEV_INTEGRITY=n build, rebase on user copy refactor]

Signed-off-by: Stanley Zhang <stazhang@purestorage.com>
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Stanley Zhang

drivers/block/ublk_drv.c

@@ -1040,6 +1040,33 @@ static size_t ublk_copy_user_pages(const struct request *req,
 	return done;
 }
 
+#ifdef CONFIG_BLK_DEV_INTEGRITY
+static size_t ublk_copy_user_integrity(const struct request *req,
+		unsigned offset, struct iov_iter *uiter, int dir)
+{
+	size_t done = 0;
+	struct bio *bio = req->bio;
+	struct bvec_iter iter;
+	struct bio_vec iv;
+
+	if (!blk_integrity_rq(req))
+		return 0;
+
+	bio_for_each_integrity_vec(iv, bio, iter) {
+		if (!ublk_copy_user_bvec(&iv, &offset, uiter, dir, &done))
+			break;
+	}
+
+	return done;
+}
+#else /* #ifdef CONFIG_BLK_DEV_INTEGRITY */
+static size_t ublk_copy_user_integrity(const struct request *req,
+		unsigned offset, struct iov_iter *uiter, int dir)
+{
+	return 0;
+}
+#endif /* #ifdef CONFIG_BLK_DEV_INTEGRITY */
+
 static inline bool ublk_need_map_req(const struct request *req)
 {
 	return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;
@@ -2668,6 +2695,8 @@ ublk_user_copy(struct kiocb *iocb, struct iov_iter *iter, int dir)
 	struct ublk_queue *ubq;
 	struct request *req;
 	struct ublk_io *io;
+	unsigned data_len;
+	bool is_integrity;
 	size_t buf_off;
 	u16 tag, q_id;
 	ssize_t ret;
@@ -2681,6 +2710,10 @@ ublk_user_copy(struct kiocb *iocb, struct iov_iter *iter, int dir)
 	tag = ublk_pos_to_tag(iocb->ki_pos);
 	q_id = ublk_pos_to_hwq(iocb->ki_pos);
 	buf_off = ublk_pos_to_buf_off(iocb->ki_pos);
+	is_integrity = !!(iocb->ki_pos & UBLKSRV_IO_INTEGRITY_FLAG);
+
+	if (unlikely(!ublk_dev_support_integrity(ub) && is_integrity))
+		return -EINVAL;
 
 	if (q_id >= ub->dev_info.nr_hw_queues)
 		return -EINVAL;
@@ -2697,7 +2730,14 @@ ublk_user_copy(struct kiocb *iocb, struct iov_iter *iter, int dir)
 	if (!req)
 		return -EINVAL;
 
-	if (buf_off > blk_rq_bytes(req)) {
+	if (is_integrity) {
+		struct blk_integrity *bi = &req->q->limits.integrity;
+
+		data_len = bio_integrity_bytes(bi, blk_rq_sectors(req));
+	} else {
+		data_len = blk_rq_bytes(req);
+	}
+	if (buf_off > data_len) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -2707,7 +2747,10 @@ ublk_user_copy(struct kiocb *iocb, struct iov_iter *iter, int dir)
 		goto out;
 	}
 
-	ret = ublk_copy_user_pages(req, buf_off, iter, dir);
+	if (is_integrity)
+		ret = ublk_copy_user_integrity(req, buf_off, iter, dir);
+	else
+		ret = ublk_copy_user_pages(req, buf_off, iter, dir);
 
 out:
 	ublk_put_req_ref(io, req);
@@ -3948,6 +3991,12 @@ static int __init ublk_init(void)
 
 	BUILD_BUG_ON((u64)UBLKSRV_IO_BUF_OFFSET +
 			UBLKSRV_IO_BUF_TOTAL_SIZE < UBLKSRV_IO_BUF_OFFSET);
+	/*
+	 * Ensure UBLKSRV_IO_BUF_OFFSET + UBLKSRV_IO_BUF_TOTAL_SIZE
+	 * doesn't overflow into UBLKSRV_IO_INTEGRITY_FLAG
+	 */
+	BUILD_BUG_ON(UBLKSRV_IO_BUF_OFFSET + UBLKSRV_IO_BUF_TOTAL_SIZE >=
+		     UBLKSRV_IO_INTEGRITY_FLAG);
 	BUILD_BUG_ON(sizeof(struct ublk_auto_buf_reg) != 8);
 
 	init_waitqueue_head(&ublk_idr_wq);

include/uapi/linux/ublk_cmd.h

@@ -134,6 +134,10 @@
 #define UBLKSRV_IO_BUF_TOTAL_BITS	(UBLK_QID_OFF + UBLK_QID_BITS)
 #define UBLKSRV_IO_BUF_TOTAL_SIZE	(1ULL << UBLKSRV_IO_BUF_TOTAL_BITS)
 
+/* Copy to/from request integrity buffer instead of data buffer */
+#define UBLK_INTEGRITY_FLAG_OFF 62
+#define UBLKSRV_IO_INTEGRITY_FLAG (1ULL << UBLK_INTEGRITY_FLAG_OFF)
+
 /*
  * ublk server can register data buffers for incoming I/O requests with a sparse
  * io_uring buffer table. The request buffer can then be used as the data buffer