libceph: don't mark footer complete before it is

This is a nit, but prepare_write_message() sets the FOOTER_COMPLETE
flag before the CRC for the data portion (recorded in the footer)
has been completely computed.  Hold off setting the complete flag
until we've decided it's ready to send.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 1b92e3b..5354d59 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -592,6 +592,8 @@
 	struct ceph_msg *m = con->out_msg;
 	int v = con->out_kvec_left;
 
+	m->footer.flags |= CEPH_MSG_FOOTER_COMPLETE;
+
 	dout("prepare_write_message_footer %p\n", con);
 	con->out_kvec_is_msg = true;
 	con->out_kvec[v].iov_base = &m->footer;
@@ -665,7 +667,7 @@
 	/* fill in crc (except data pages), footer */
 	crc = crc32c(0, &m->hdr, offsetof(struct ceph_msg_header, crc));
 	con->out_msg->hdr.crc = cpu_to_le32(crc);
-	con->out_msg->footer.flags = CEPH_MSG_FOOTER_COMPLETE;
+	con->out_msg->footer.flags = 0;
 
 	crc = crc32c(0, m->front.iov_base, m->front.iov_len);
 	con->out_msg->footer.front_crc = cpu_to_le32(crc);