libceph: define osd data initialization helpers

Define and use functions that encapsulate the initializion of a
ceph_osd_data structure.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 5d8ce79..cf9032a 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -342,10 +342,8 @@
 		}
 		pages[i] = page;
 	}
-	req->r_data_in.type = CEPH_OSD_DATA_TYPE_PAGES;
-	req->r_data_in.pages = pages;
-	req->r_data_in.length = len;
-	req->r_data_in.alignment = 0;
+	ceph_osd_data_pages_init(&req->r_data_in, pages, len, 0,
+					false, false);
 	req->r_callback = finish_read;
 	req->r_inode = inode;
 
@@ -917,11 +915,8 @@
 		dout("writepages got %d pages at %llu~%llu\n",
 		     locked_pages, offset, len);
 
-		req->r_data_out.type = CEPH_OSD_DATA_TYPE_PAGES;
-		req->r_data_out.pages = pages;
-		req->r_data_out.length = len;
-		req->r_data_out.alignment = 0;
-		req->r_data_out.pages_from_pool = !!pool;
+		ceph_osd_data_pages_init(&req->r_data_out, pages, len, 0,
+						!!pool, false);
 
 		pages = NULL;	/* request message now owns the pages array */
 		pool = NULL;