[DLM] clear sbflags on lock master

RH 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.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 6088a16926bf..30878defaeb6 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -2372,6 +2372,7 @@ static int send_lookup_reply(struct dlm_ls *ls, struct dlm_message *ms_in,
 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);
 }