Date: Fri, 27 Oct 2006 10:13:05 -0500
From: David Teigland <teigland@redhat.com>
Subject: [RHEL5 PATCH] dlm: clear sbflags on lock master

BZ 211622

The ALTMODE flag can be set in the lock master's copy of the lock but
never cleared, so ALTMODE will also be returned in a subsequent conversion
of the lock when it shouldn't be.  This results in lock_dlm incorrectly
switching to the alternate lock mode when returning the result to gfs
which then asserts when it sees the wrong lock state.  The fix is to
propagate the cleared sbflags value to the master node when the lock is
requested.  QA's d_rwrandirectlarge test triggers this bug very quickly.  

diff -ur linux-2.6.19-rc1-orig/fs/dlm/lock.c linux-2.6.19-rc1-test/fs/dlm/lock.c
--- linux-2.6.19-rc1-orig/fs/dlm/lock.c	2006-10-05 11:45:35.000000000 -0500
+++ linux-2.6.19-rc1-test/fs/dlm/lock.c	2006-10-26 14:55:38.166052089 -0500
@@ -2372,6 +2372,7 @@
 static void receive_flags(struct dlm_lkb *lkb, struct dlm_message *ms)
 {
 	lkb->lkb_exflags = ms->m_exflags;
+	lkb->lkb_sbflags = ms->m_sbflags;
 	lkb->lkb_flags = (lkb->lkb_flags & 0xFFFF0000) |
 		         (ms->m_flags & 0x0000FFFF);
 }