[PATCH] bsg : Add support for io vectors in bsg

[Deepak Colluru <deepakrc@gmail.com>]

From: Deepak Colluru <deepakrc@gmail.com>

Add support for io vectors in bsg.

Signed-off-by: Deepak Colluru <deepakrc@gmail.com>
---
  bsg.c |   52 +++++++++++++++++++++++++++++++++++++++++++++++++---
  1 file changed, 49 insertions(+), 3 deletions(-)

diff --git a/block/bsg.c b/block/bsg.c
index 8e181ab..78f47ed 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -245,7 +245,7 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
  	struct request_queue *q = bd->queue;
  	struct request *rq, *next_rq = NULL;
  	int ret, rw;
-	unsigned int dxfer_len;
+	unsigned int dxfer_len, iovec_count = 0;
  	void *dxferp = NULL;

  	dprintk("map hdr %llx/%u %llx/%u\n", (unsigned long long) hdr->dout_xferp,
@@ -281,7 +281,31 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
  		rq->next_rq = next_rq;

  		dxferp = (void*)(unsigned long)hdr->din_xferp;
-		ret =  blk_rq_map_user(q, next_rq, dxferp, hdr->din_xfer_len);
+		iovec_count = hdr->din_iovec_count;
+		dxfer_len = hdr->din_xfer_len;
+
+		if (iovec_count) {
+			const int size = sizeof(struct sg_iovec) * iovec_count;
+			struct sg_iovec *iov;
+
+			iov = kmalloc(size, GFP_KERNEL);
+			if (!iov) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			if (copy_from_user(iov, dxferp, size)) {
+				kfree(iov);
+				ret = -EFAULT;
+				goto out;
+			}
+			ret = blk_rq_map_user_iov(q, rq, iov, iovec_count,
+								dxfer_len);
+			kfree(iov);
+		} else {
+			ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
+		}
+
  		if (ret)
  			goto out;
  	}
@@ -289,14 +313,36 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr)
  	if (hdr->dout_xfer_len) {
  		dxfer_len = hdr->dout_xfer_len;
  		dxferp = (void*)(unsigned long)hdr->dout_xferp;
+		iovec_count = hdr->dout_iovec_count;
  	} else if (hdr->din_xfer_len) {
  		dxfer_len = hdr->din_xfer_len;
  		dxferp = (void*)(unsigned long)hdr->din_xferp;
+		iovec_count = hdr->din_iovec_count;
  	} else
  		dxfer_len = 0;

  	if (dxfer_len) {
-		ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
+		if (iovec_count) {
+			const int size = sizeof(struct sg_iovec) * iovec_count;
+			struct sg_iovec *iov;
+
+			iov = kmalloc(size, GFP_KERNEL);
+			if (!iov) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			if (copy_from_user(iov, dxferp, size)) {
+				kfree(iov);
+				ret = -EFAULT;
+				goto out;
+			}
+			ret = blk_rq_map_user_iov(q, rq, iov, iovec_count,
+								dxfer_len);
+			kfree(iov);
+		} else {
+			ret = blk_rq_map_user(q, rq, dxferp, dxfer_len);
+		}
  		if (ret)
  			goto out;
  	}