libceph: isolate message page field manipulation

Define a function ceph_msg_data_set_pages(), which more clearly
abstracts the assignment page-related fields for data in a ceph
message structure.  Use this new function in the osd client and mds
client.

Ideally, these fields would never be set more than once (with
BUG_ON() calls to guarantee that).  At the moment though the osd
client sets these every time it receives a message, and in the event
of a communication problem this can happen more than once.  (This
will be resolved shortly, but setting up these helpers first makes
it all a bit easier to work with.)

Rearrange the field order in a ceph_msg structure to group those
that are used to define the possible data payloads.

This partially resolves:
    http://tracker.ceph.com/issues/4263

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index ecfb738bca30..90198a407023 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1721,8 +1721,8 @@ static struct ceph_msg *create_request_message(struct ceph_mds_client *mdsc,
         msg->front.iov_len = p - msg->front.iov_base;
         msg->hdr.front_len = cpu_to_le32(msg->front.iov_len);
 
-        msg->pages = req->r_pages;
-        msg->page_count = req->r_num_pages;
+        ceph_msg_data_set_pages(msg, req->r_pages, req->r_num_pages, 0);
+
         msg->hdr.data_len = cpu_to_le32(req->r_data_len);
         msg->hdr.data_off = cpu_to_le16(0);