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[DLM] block dlm_recv in recovery transition

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Introduce a per-lockspace rwsem that's held in read mode by dlm_recv
threads while working in the dlm.  This allows dlm_recv activity to be
suspended when the lockspace transitions to, from and between recovery
cycles.

The specific bug prompting this change is one where an in-progress
recovery cycle is aborted by a new recovery cycle.  While dlm_recv was
processing a recovery message, the recovery cycle was aborted and
dlm_recoverd began cleaning up.  dlm_recv decremented recover_locks_count
on an rsb after dlm_recoverd had reset it to zero.  This is fixed by
suspending dlm_recv (taking write lock on the rwsem) before aborting the
current recovery.

The transitions to/from normal and recovery modes are simplified by using
this new ability to block dlm_recv.  The switch from normal to recovery
mode means dlm_recv goes from processing locking messages, to saving them
for later, and vice versa.  Races are avoided by blocking dlm_recv when
setting the flag that switches between modes.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
This commit is contained in:
David Teigland
2007-09-27 15:53:38 -05:00
committed by Steven Whitehouse
parent b434eda6fd
commit c36258b592
11 changed files with 161 additions and 152 deletions
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17
fs/dlm/midcomms.c
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@ -2,7 +2,7 @@
*******************************************************************************
**
** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
** Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
** Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
**
** This copyrighted material is made available to anyone wishing to use,
** modify, copy, or redistribute it subject to the terms and conditions
@ -27,7 +27,6 @@
#include "dlm_internal.h"
#include "lowcomms.h"
#include "config.h"
#include "rcom.h"
#include "lock.h"
#include "midcomms.h"
@ -117,19 +116,7 @@ int dlm_process_incoming_buffer(int nodeid, const void *base,
offset &= (limit - 1);
len -= msglen;
switch (msg->h_cmd) {
case DLM_MSG:
dlm_receive_message(msg, nodeid, 0);
break;
case DLM_RCOM:
dlm_receive_rcom(msg, nodeid);
break;
default:
log_print("unknown msg type %x from %u: %u %u %u %u",
msg->h_cmd, nodeid, msglen, len, offset, ret);
}
dlm_receive_buffer(msg, nodeid);
}
if (msg != (struct dlm_header *) __tmp)