1 files changed, 254 insertions, 0 deletions
diff --git a/block/blk-map.c b/block/blk-map.c
new file mode 100644
index 000000000..9d8627acc
--- /dev/null
+++ b/block/blk-map.c
@@ -0,0 +1,254 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Functions related to mapping data to requests
+ */
+#include <linux/kernel.h>
+#include <linux/sched/task_stack.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/uio.h>
+
+#include "blk.h"
+
+/*
+ * Append a bio to a passthrough request.  Only works if the bio can be merged
+ * into the request based on the driver constraints.
+ */
+int blk_rq_append_bio(struct request *rq, struct bio **bio)
+{
+	struct bio *orig_bio = *bio;
+
+	blk_queue_bounce(rq->q, bio);
+
+	if (!rq->bio) {
+		blk_rq_bio_prep(rq->q, rq, *bio);
+	} else {
+		if (!ll_back_merge_fn(rq->q, rq, *bio)) {
+			if (orig_bio != *bio) {
+				bio_put(*bio);
+				*bio = orig_bio;
+			}
+			return -EINVAL;
+		}
+
+		rq->biotail->bi_next = *bio;
+		rq->biotail = *bio;
+		rq->__data_len += (*bio)->bi_iter.bi_size;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(blk_rq_append_bio);
+
+static int __blk_rq_unmap_user(struct bio *bio)
+{
+	int ret = 0;
+
+	if (bio) {
+		if (bio_flagged(bio, BIO_USER_MAPPED))
+			bio_unmap_user(bio);
+		else
+			ret = bio_uncopy_user(bio);
+	}
+
+	return ret;
+}
+
+static int __blk_rq_map_user_iov(struct request *rq,
+		struct rq_map_data *map_data, struct iov_iter *iter,
+		gfp_t gfp_mask, bool copy)
+{
+	struct request_queue *q = rq->q;
+	struct bio *bio, *orig_bio;
+	int ret;
+
+	if (copy)
+		bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
+	else
+		bio = bio_map_user_iov(q, iter, gfp_mask);
+
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	bio->bi_opf &= ~REQ_OP_MASK;
+	bio->bi_opf |= req_op(rq);
+
+	orig_bio = bio;
+
+	/*
+	 * We link the bounce buffer in and could have to traverse it
+	 * later so we have to get a ref to prevent it from being freed
+	 */
+	ret = blk_rq_append_bio(rq, &bio);
+	if (ret) {
+		__blk_rq_unmap_user(orig_bio);
+		return ret;
+	}
+	bio_get(bio);
+
+	return 0;
+}
+
+/**
+ * blk_rq_map_user_iov - map user data to a request, for passthrough requests
+ * @q:		request queue where request should be inserted
+ * @rq:		request to map data to
+ * @map_data:   pointer to the rq_map_data holding pages (if necessary)
+ * @iter:	iovec iterator
+ * @gfp_mask:	memory allocation flags
+ *
+ * Description:
+ *    Data will be mapped directly for zero copy I/O, if possible. Otherwise
+ *    a kernel bounce buffer is used.
+ *
+ *    A matching blk_rq_unmap_user() must be issued at the end of I/O, while
+ *    still in process context.
+ *
+ *    Note: The mapped bio may need to be bounced through blk_queue_bounce()
+ *    before being submitted to the device, as pages mapped may be out of
+ *    reach. It's the callers responsibility to make sure this happens. The
+ *    original bio must be passed back in to blk_rq_unmap_user() for proper
+ *    unmapping.
+ */
+int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
+			struct rq_map_data *map_data,
+			const struct iov_iter *iter, gfp_t gfp_mask)
+{
+	bool copy = false;
+	unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
+	struct bio *bio = NULL;
+	struct iov_iter i;
+	int ret = -EINVAL;
+
+	if (!iter_is_iovec(iter))
+		goto fail;
+
+	if (map_data)
+		copy = true;
+	else if (iov_iter_alignment(iter) & align)
+		copy = true;
+	else if (queue_virt_boundary(q))
+		copy = queue_virt_boundary(q) & iov_iter_gap_alignment(iter);
+
+	i = *iter;
+	do {
+		ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
+		if (ret)
+			goto unmap_rq;
+		if (!bio)
+			bio = rq->bio;
+	} while (iov_iter_count(&i));
+
+	if (!bio_flagged(bio, BIO_USER_MAPPED))
+		rq->rq_flags |= RQF_COPY_USER;
+	return 0;
+
+unmap_rq:
+	blk_rq_unmap_user(bio);
+fail:
+	rq->bio = NULL;
+	return ret;
+}
+EXPORT_SYMBOL(blk_rq_map_user_iov);
+
+int blk_rq_map_user(struct request_queue *q, struct request *rq,
+		    struct rq_map_data *map_data, void __user *ubuf,
+		    unsigned long len, gfp_t gfp_mask)
+{
+	struct iovec iov;
+	struct iov_iter i;
+	int ret = import_single_range(rq_data_dir(rq), ubuf, len, &iov, &i);
+
+	if (unlikely(ret < 0))
+		return ret;
+
+	return blk_rq_map_user_iov(q, rq, map_data, &i, gfp_mask);
+}
+EXPORT_SYMBOL(blk_rq_map_user);
+
+/**
+ * blk_rq_unmap_user - unmap a request with user data
+ * @bio:	       start of bio list
+ *
+ * Description:
+ *    Unmap a rq previously mapped by blk_rq_map_user(). The caller must
+ *    supply the original rq->bio from the blk_rq_map_user() return, since
+ *    the I/O completion may have changed rq->bio.
+ */
+int blk_rq_unmap_user(struct bio *bio)
+{
+	struct bio *mapped_bio;
+	int ret = 0, ret2;
+
+	while (bio) {
+		mapped_bio = bio;
+		if (unlikely(bio_flagged(bio, BIO_BOUNCED)))
+			mapped_bio = bio->bi_private;
+
+		ret2 = __blk_rq_unmap_user(mapped_bio);
+		if (ret2 && !ret)
+			ret = ret2;
+
+		mapped_bio = bio;
+		bio = bio->bi_next;
+		bio_put(mapped_bio);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(blk_rq_unmap_user);
+
+/**
+ * blk_rq_map_kern - map kernel data to a request, for passthrough requests
+ * @q:		request queue where request should be inserted
+ * @rq:		request to fill
+ * @kbuf:	the kernel buffer
+ * @len:	length of user data
+ * @gfp_mask:	memory allocation flags
+ *
+ * Description:
+ *    Data will be mapped directly if possible. Otherwise a bounce
+ *    buffer is used. Can be called multiple times to append multiple
+ *    buffers.
+ */
+int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
+		    unsigned int len, gfp_t gfp_mask)
+{
+	int reading = rq_data_dir(rq) == READ;
+	unsigned long addr = (unsigned long) kbuf;
+	int do_copy = 0;
+	struct bio *bio, *orig_bio;
+	int ret;
+
+	if (len > (queue_max_hw_sectors(q) << 9))
+		return -EINVAL;
+	if (!len || !kbuf)
+		return -EINVAL;
+
+	do_copy = !blk_rq_aligned(q, addr, len) || object_is_on_stack(kbuf);
+	if (do_copy)
+		bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading);
+	else
+		bio = bio_map_kern(q, kbuf, len, gfp_mask);
+
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	bio->bi_opf &= ~REQ_OP_MASK;
+	bio->bi_opf |= req_op(rq);
+
+	if (do_copy)
+		rq->rq_flags |= RQF_COPY_USER;
+
+	orig_bio = bio;
+	ret = blk_rq_append_bio(rq, &bio);
+	if (unlikely(ret)) {
+		/* request is too big */
+		bio_put(orig_bio);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(blk_rq_map_kern);