From: Ilya Dryomov <idryomov@xxxxxxxxx> commit 28e1581c3b4ea5f98530064a103c6217bedeea73 upstream. con->out_msg must be cleared on Policy::stateful_server (!CEPH_MSG_CONNECT_LOSSY) faults. Not doing so botches the reconnection attempt, because after writing the banner the messenger moves on to writing the data section of that message (either from where it got interrupted by the connection reset or from the beginning) instead of writing struct ceph_msg_connect. This results in a bizarre error message because the server sends CEPH_MSGR_TAG_BADPROTOVER but we think we wrote struct ceph_msg_connect: libceph: mds0 (1)172.21.15.45:6828 socket error on write ceph: mds0 reconnect start libceph: mds0 (1)172.21.15.45:6829 socket closed (con state OPEN) libceph: mds0 (1)172.21.15.45:6829 protocol version mismatch, my 32 != server's 32 libceph: mds0 (1)172.21.15.45:6829 protocol version mismatch AFAICT this bug goes back to the dawn of the kernel client. The reason it survived for so long is that only MDS sessions are stateful and only two MDS messages have a data section: CEPH_MSG_CLIENT_RECONNECT (always, but reconnecting is rare) and CEPH_MSG_CLIENT_REQUEST (only when xattrs are involved). The connection has to get reset precisely when such message is being sent -- in this case it was the former. Cc: stable@xxxxxxxxxxxxxxx Link: https://tracker.ceph.com/issues/47723 Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx> Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ceph/messenger.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/net/ceph/messenger.c +++ b/net/ceph/messenger.c @@ -2976,6 +2976,11 @@ static void con_fault(struct ceph_connec ceph_msg_put(con->in_msg); con->in_msg = NULL; } + if (con->out_msg) { + BUG_ON(con->out_msg->con != con); + ceph_msg_put(con->out_msg); + con->out_msg = NULL; + } /* Requeue anything that hasn't been acked */ list_splice_init(&con->out_sent, &con->out_queue);
