constify blk_rq_map_user_iov() and friends

sg_iovec array passed to it can be const

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/bio.c b/fs/bio.c
index 8754e7b..7065837 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1003,7 +1003,7 @@
 };
 
 static void bio_set_map_data(struct bio_map_data *bmd, struct bio *bio,
-			     struct sg_iovec *iov, int iov_count,
+			     const struct sg_iovec *iov, int iov_count,
 			     int is_our_pages)
 {
 	memcpy(bmd->sgvecs, iov, sizeof(struct sg_iovec) * iov_count);
@@ -1023,7 +1023,7 @@
 		       sizeof(struct sg_iovec) * iov_count, gfp_mask);
 }
 
-static int __bio_copy_iov(struct bio *bio, struct sg_iovec *iov, int iov_count,
+static int __bio_copy_iov(struct bio *bio, const struct sg_iovec *iov, int iov_count,
 			  int to_user, int from_user, int do_free_page)
 {
 	int ret = 0, i;
@@ -1121,7 +1121,7 @@
  */
 struct bio *bio_copy_user_iov(struct request_queue *q,
 			      struct rq_map_data *map_data,
-			      struct sg_iovec *iov, int iov_count,
+			      const struct sg_iovec *iov, int iov_count,
 			      int write_to_vm, gfp_t gfp_mask)
 {
 	struct bio_map_data *bmd;
@@ -1260,7 +1260,7 @@
 
 static struct bio *__bio_map_user_iov(struct request_queue *q,
 				      struct block_device *bdev,
-				      struct sg_iovec *iov, int iov_count,
+				      const struct sg_iovec *iov, int iov_count,
 				      int write_to_vm, gfp_t gfp_mask)
 {
 	int i, j;
@@ -1408,7 +1408,7 @@
  *	device. Returns an error pointer in case of error.
  */
 struct bio *bio_map_user_iov(struct request_queue *q, struct block_device *bdev,
-			     struct sg_iovec *iov, int iov_count,
+			     const struct sg_iovec *iov, int iov_count,
 			     int write_to_vm, gfp_t gfp_mask)
 {
 	struct bio *bio;