ceph: make page alignment explicit in osd interface

We used to infer alignment of IOs within a page based on the file offset,
which assumed they matched.  This broke with direct IO that was not aligned
to pages (e.g., 512-byte aligned IO).  We were also trusting the alignment
specified in the OSD reply, which could have been adjusted by the server.

Explicitly specify the page alignment when setting up OSD IO requests.

Signed-off-by: Sage Weil <sage@newdream.net>
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 7bc0fbd..8153ee5 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1752,7 +1752,7 @@
 		return 0;
 	}
 
-	dout("do_getattr inode %p mask %s\n", inode, ceph_cap_string(mask));
+	dout("do_getattr inode %p mask %s mode 0%o\n", inode, ceph_cap_string(mask), inode->i_mode);
 	if (ceph_caps_issued_mask(ceph_inode(inode), mask, 1))
 		return 0;