ceph: only set message data pointers if non-empty

Change it so we only assign outgoing data information for messages
if there is outgoing data to send.

This then allows us to add a few more (currently commented-out)
assertions.

This is related to:
    http://tracker.ceph.com/issues/4284

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Greg Farnum <greg@inktank.com>

1 files changed, 10 insertions, 3 deletions

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 3b2aa8702ae0..600d770d70f7 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1721,7 +1721,11 @@ 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);
 
-        ceph_msg_data_set_pages(msg, req->r_pages, req->r_data_len, 0);
+        if (req->r_data_len) {
+                /* outbound data set only by ceph_sync_setxattr() */
+                BUG_ON(!req->r_pages);
+                ceph_msg_data_set_pages(msg, req->r_pages, req->r_data_len, 0);
+        }
 
         msg->hdr.data_len = cpu_to_le32(req->r_data_len);
         msg->hdr.data_off = cpu_to_le16(0);
@@ -2603,10 +2607,13 @@ static void send_mds_reconnect(struct ceph_mds_client *mdsc,
                         goto fail;
         }
 
-        ceph_msg_data_set_pagelist(reply, pagelist);
         if (recon_state.flock)
                 reply->hdr.version = cpu_to_le16(2);
-        reply->hdr.data_len = cpu_to_le32(pagelist->length);
+        if (pagelist->length) {
+                /* set up outbound data if we have any */
+                reply->hdr.data_len = cpu_to_le32(pagelist->length);
+                ceph_msg_data_set_pagelist(reply, pagelist);
+        }
         ceph_con_send(&session->s_con, reply);
 
         mutex_unlock(&session->s_mutex);