commit ebf18f47093e968105767eed4a0aa155e86b224e
author Alex Elder <elder@inktank.com> Mon Mar 04 22:29:57 2013 -0600
committer Sage Weil <sage@inktank.com> Wed May 01 21:16:41 2013 -0700
tree 90122481017a894850e46b8c86987bd31548fddc
parent 27fa83852ba275361eaa1a1283cf6704fa8191a6

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>

fs/ceph/mds_client.c

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 3b2aa87..600d770 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -1721,7 +1721,11 @@
 	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 @@
 			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);