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

[Deepak Colluru <deepakrc@xxxxxxxxx>]

From: Deepak Colluru <deepakrc@xxxxxxxxx>

Add support for io vectors in bsg.

Signed-off-by: Deepak Colluru <deepakrc@xxxxxxxxx>
---
 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;
 	}
-
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