1 files changed, 264 insertions, 0 deletions
diff --git a/block/blk-map.c b/block/blk-map.c
new file mode 100644
index 0000000..916cfc9
--- /dev/null
+++ b/block/blk-map.c
@@ -0,0 +1,264 @@
+/*
+ * Functions related to mapping data to requests
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+
+#include "blk.h"
+
+int blk_rq_append_bio(struct request_queue *q, struct request *rq,
+		      struct bio *bio)
+{
+	if (!rq->bio)
+		blk_rq_bio_prep(q, rq, bio);
+	else if (!ll_back_merge_fn(q, rq, bio))
+		return -EINVAL;
+	else {
+		rq->biotail->bi_next = bio;
+		rq->biotail = bio;
+
+		rq->data_len += bio->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(struct request_queue *q, struct request *rq,
+			     void __user *ubuf, unsigned int len)
+{
+	unsigned long uaddr;
+	struct bio *bio, *orig_bio;
+	int reading, ret;
+
+	reading = rq_data_dir(rq) == READ;
+
+	/*
+	 * if alignment requirement is satisfied, map in user pages for
+	 * direct dma. else, set up kernel bounce buffers
+	 */
+	uaddr = (unsigned long) ubuf;
+	if (!(uaddr & queue_dma_alignment(q)) && !(len & queue_dma_alignment(q)))
+		bio = bio_map_user(q, NULL, uaddr, len, reading);
+	else
+		bio = bio_copy_user(q, uaddr, len, reading);
+
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	orig_bio = bio;
+	blk_queue_bounce(q, &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
+	 */
+	bio_get(bio);
+
+	ret = blk_rq_append_bio(q, rq, bio);
+	if (!ret)
+		return bio->bi_size;
+
+	/* if it was boucned we must call the end io function */
+	bio_endio(bio, 0);
+	__blk_rq_unmap_user(orig_bio);
+	bio_put(bio);
+	return ret;
+}
+
+/**
+ * blk_rq_map_user - map user data to a request, for REQ_BLOCK_PC usage
+ * @q:		request queue where request should be inserted
+ * @rq:		request structure to fill
+ * @ubuf:	the user buffer
+ * @len:	length of user data
+ *
+ * Description:
+ *    Data will be mapped directly for zero copy io, if possible. Otherwise
+ *    a kernel bounce buffer is used.
+ *
+ *    A matching blk_rq_unmap_user() must be issued at the end of io, 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(struct request_queue *q, struct request *rq,
+		    void __user *ubuf, unsigned long len)
+{
+	unsigned long bytes_read = 0;
+	struct bio *bio = NULL;
+	int ret;
+
+	if (len > (q->max_hw_sectors << 9))
+		return -EINVAL;
+	if (!len || !ubuf)
+		return -EINVAL;
+
+	while (bytes_read != len) {
+		unsigned long map_len, end, start;
+
+		map_len = min_t(unsigned long, len - bytes_read, BIO_MAX_SIZE);
+		end = ((unsigned long)ubuf + map_len + PAGE_SIZE - 1)
+								>> PAGE_SHIFT;
+		start = (unsigned long)ubuf >> PAGE_SHIFT;
+
+		/*
+		 * A bad offset could cause us to require BIO_MAX_PAGES + 1
+		 * pages. If this happens we just lower the requested
+		 * mapping len by a page so that we can fit
+		 */
+		if (end - start > BIO_MAX_PAGES)
+			map_len -= PAGE_SIZE;
+
+		ret = __blk_rq_map_user(q, rq, ubuf, map_len);
+		if (ret < 0)
+			goto unmap_rq;
+		if (!bio)
+			bio = rq->bio;
+		bytes_read += ret;
+		ubuf += ret;
+	}
+
+	rq->buffer = rq->data = NULL;
+	return 0;
+unmap_rq:
+	blk_rq_unmap_user(bio);
+	return ret;
+}
+
+EXPORT_SYMBOL(blk_rq_map_user);
+
+/**
+ * blk_rq_map_user_iov - map user data to a request, for REQ_BLOCK_PC usage
+ * @q:		request queue where request should be inserted
+ * @rq:		request to map data to
+ * @iov:	pointer to the iovec
+ * @iov_count:	number of elements in the iovec
+ * @len:	I/O byte count
+ *
+ * Description:
+ *    Data will be mapped directly for zero copy io, if possible. Otherwise
+ *    a kernel bounce buffer is used.
+ *
+ *    A matching blk_rq_unmap_user() must be issued at the end of io, 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 sg_iovec *iov, int iov_count, unsigned int len)
+{
+	struct bio *bio;
+
+	if (!iov || iov_count <= 0)
+		return -EINVAL;
+
+	/* we don't allow misaligned data like bio_map_user() does.  If the
+	 * user is using sg, they're expected to know the alignment constraints
+	 * and respect them accordingly */
+	bio = bio_map_user_iov(q, NULL, iov, iov_count, rq_data_dir(rq)== READ);
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	if (bio->bi_size != len) {
+		bio_endio(bio, 0);
+		bio_unmap_user(bio);
+		return -EINVAL;
+	}
+
+	bio_get(bio);
+	blk_rq_bio_prep(q, rq, bio);
+	rq->buffer = rq->data = NULL;
+	return 0;
+}
+
+EXPORT_SYMBOL(blk_rq_map_user_iov);
+
+/**
+ * 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 io 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 REQ_BLOCK_PC usage
+ * @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
+ */
+int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
+		    unsigned int len, gfp_t gfp_mask)
+{
+	struct bio *bio;
+
+	if (len > (q->max_hw_sectors << 9))
+		return -EINVAL;
+	if (!len || !kbuf)
+		return -EINVAL;
+
+	bio = bio_map_kern(q, kbuf, len, gfp_mask);
+	if (IS_ERR(bio))
+		return PTR_ERR(bio);
+
+	if (rq_data_dir(rq) == WRITE)
+		bio->bi_rw |= (1 << BIO_RW);
+
+	blk_rq_bio_prep(q, rq, bio);
+	blk_queue_bounce(q, &rq->bio);
+	rq->buffer = rq->data = NULL;
+	return 0;
+}
+
+EXPORT_SYMBOL(blk_rq_map_kern);