From: Mike Christie <mchristi@redhat.com>
Date: Fri, 18 Jun 2010 19:09:52 -0500
Subject: [iscsi] fix slow failover times
Message-id: <1276906192-2764-1-git-send-email-mchristi@redhat.com>
O-Subject: [PATCH RHEL 5.3.z]: Fix iscsi failover/shutdown (ver 2)
Bugzilla: 583898
RH-Acked-by: Tomas Henzl <thenzl@redhat.com>

From: Mike Christie <mchristi@redhat.com>

This is for BZ 583898.

This patches fixes a couple bugs in the shutdown/relogin code:

1. If we are trying to log out of a iscsi connection and close the
socket at the same time there was a problem with the connection
(someone pulled a cable, switch died, etc), and while lots of IO
was being sent by the iscsi layer, then the network code could be
waiting in sk_stream_wait_memory. This patch adds a wake_up on the sock
so we do not have to wait the full sk_sndtimeo secs.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d7d05548a62c87ee55b0c81933669177f885aa8d
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b64e77f70b8c11766e967e3485331a9e6ef01390

2. There is a race where the xmit or scsi eh thread can reset
the session->state while the recovery code thread is trying
to clean up the session resources.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=4ae0a6c15efcc37e94e3f30e3533bdec03c53126

I can replicate the problem here and verified the patch fixes
the problem. I also ran the iscsi test scripts to check for
regressions.

Ver 2:
- Rebuild and retest patch against current 5.3.z stream kernel.

---
 drivers/scsi/iscsi_tcp.c |    9 +++++++++
 drivers/scsi/libiscsi.c  |    5 +++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index e7a7978..98fca22 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -1870,6 +1870,15 @@ iscsi_tcp_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
 {
 	struct iscsi_conn *conn = cls_conn->dd_data;
 	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct socket *sock = tcp_conn->sock;
+
+	if (!sock)
+		return;
+
+	if (sock->sk->sk_sleep) {
+		sock->sk->sk_err = EIO;
+		wake_up_interruptible(sock->sk->sk_sleep);
+	}
 
 	iscsi_conn_stop(cls_conn, flag);
 	iscsi_tcp_release_conn(conn);
diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 526218a..f0d3694 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -2059,14 +2059,15 @@ static void iscsi_start_session_recovery(struct iscsi_session *session,
 		session->state = ISCSI_STATE_TERMINATE;
 	else if (conn->stop_stage != STOP_CONN_RECOVER)
 		session->state = ISCSI_STATE_IN_RECOVERY;
+
+	old_stop_stage = conn->stop_stage;
+	conn->stop_stage = flag;
 	spin_unlock_bh(&session->lock);
 
 	del_timer_sync(&conn->transport_timer);
 	iscsi_suspend_tx(conn);
 
 	spin_lock_bh(&session->lock);
-	old_stop_stage = conn->stop_stage;
-	conn->stop_stage = flag;
 	conn->c_stage = ISCSI_CONN_STOPPED;
 	spin_unlock_bh(&session->lock);
 
-- 
1.6.6.1