diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 4d6f2fe1cfe..9230402c45a 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1656,6 +1656,10 @@ static int sg_start_req(Sg_request *srp, unsigned char *cmd)
 		md->nr_entries = req_schp->k_use_sg;
 		md->offset = 0;
 		md->null_mapped = hp->dxferp ? 0 : 1;
+		if (dxfer_dir == SG_DXFER_TO_FROM_DEV)
+			md->from_user = 1;
+		else
+			md->from_user = 0;
 	}
 
 	if (iov_count) {
diff --git a/fs/bio.c b/fs/bio.c
index 1486b19fc43..76738005c8e 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -705,14 +705,13 @@ static struct bio_map_data *bio_alloc_map_data(int nr_segs, int iov_count,
 }
 
 static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
-			  struct sg_iovec *iov, int iov_count, int uncopy,
-			  int do_free_page)
+			  struct sg_iovec *iov, int iov_count,
+			  int to_user, int from_user, int do_free_page)
 {
 	int ret = 0, i;
 	struct bio_vec *bvec;
 	int iov_idx = 0;
 	unsigned int iov_off = 0;
-	int read = bio_data_dir(bio) == READ;
 
 	__bio_for_each_segment(bvec, bio, i, 0) {
 		char *bv_addr = page_address(bvec->bv_page);
@@ -727,13 +726,14 @@ static int __bio_copy_iov(struct bio *bio, struct bio_vec *iovecs,
 			iov_addr = iov[iov_idx].iov_base + iov_off;
 
 			if (!ret) {
-				if (!read && !uncopy)
-					ret = copy_from_user(bv_addr, iov_addr,
-							     bytes);
-				if (read && uncopy)
+				if (to_user)
 					ret = copy_to_user(iov_addr, bv_addr,
 							   bytes);
 
+				if (from_user)
+					ret = copy_from_user(bv_addr, iov_addr,
+							     bytes);
+
 				if (ret)
 					ret = -EFAULT;
 			}
@@ -770,7 +770,8 @@ int bio_uncopy_user(struct bio *bio)
 
 	if (!bio_flagged(bio, BIO_NULL_MAPPED))
 		ret = __bio_copy_iov(bio, bmd->iovecs, bmd->sgvecs,
-				     bmd->nr_sgvecs, 1, bmd->is_our_pages);
+				     bmd->nr_sgvecs, bio_data_dir(bio) == READ,
+				     0, bmd->is_our_pages);
 	bio_free_map_data(bmd);
 	bio_put(bio);
 	return ret;
@@ -875,8 +876,9 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
 	/*
 	 * success
 	 */
-	if (!write_to_vm && (!map_data || !map_data->null_mapped)) {
-		ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
+	if ((!write_to_vm && (!map_data || !map_data->null_mapped)) ||
+	    (map_data && map_data->from_user)) {
+		ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 1, 0);
 		if (ret)
 			goto cleanup;
 	}
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index bb3d3997870..0146e0fecf1 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -723,6 +723,7 @@ struct rq_map_data {
 	int nr_entries;
 	unsigned long offset;
 	int null_mapped;
+	int from_user;
 };
 
 struct req_iterator {