block: Convert drivers to immutable biovecs

Now that we've got a mechanism for immutable biovecs -
bi_iter.bi_bvec_done - we need to convert drivers to use primitives that
respect it instead of using the bvec array directly.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: NeilBrown <neilb@suse.de>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
diff --git a/include/linux/dm-io.h b/include/linux/dm-io.h
index f4b0aa3..a68cbe5 100644
--- a/include/linux/dm-io.h
+++ b/include/linux/dm-io.h
@@ -29,7 +29,7 @@
 
 enum dm_io_mem_type {
 	DM_IO_PAGE_LIST,/* Page list */
-	DM_IO_BVEC,	/* Bio vector */
+	DM_IO_BIO,	/* Bio vector */
 	DM_IO_VMA,	/* Virtual memory area */
 	DM_IO_KMEM,	/* Kernel memory */
 };
@@ -41,7 +41,7 @@
 
 	union {
 		struct page_list *pl;
-		struct bio_vec *bvec;
+		struct bio *bio;
 		void *vma;
 		void *addr;
 	} ptr;