[Ocfs2-devel] ocfs2/dlm: fix a race between refmap setting and clearing

[xuejiufei]

Hi,
This serial of patches is to fix the dis-order issue of
setting/clearing refmap bit described below.

Node 1                               Node 2(master)
dlmlock
dlm_do_master_request
                                dlm_master_request_handler
                                -> dlm_lockres_set_refmap_bit
dlmlock succeed
dlmunlock succeed

dlm_purge_lockres
                                dlm_deref_handler
                                -> find lock resource is in
                                   DLM_LOCK_RES_SETREF_INPROG state,
                                   so dispatch a deref work
dlm_purge_lockres succeed.

call dlmlock again
dlm_do_master_request
                                dlm_master_request_handler
                                -> dlm_lockres_set_refmap_bit

                                deref work trigger, call
                                dlm_lockres_clear_refmap_bit
                                to clear Node 1 from refmap

                                dlm_purge_lockres succeed

dlm_send_remote_lock_request
                                return DLM_IVLOCKID because
                                the lockres is not exist
BUG if the lockres is $RECOVERY

This serial of patches add a new message to keep the order of set and
clear. Other nodes can purge the lock resource only after the refmap
bit on master is cleared.

Jiufei Xue (4):
    ocfs2/dlm: add DEREF_DONE message
    ocfs2/dlm: return in progress if master can not clear the refmap
               bit right now
    ocfs2/dlm: clear DROPPING_REF flag when the master down
    ocfs2/dlm: return EINVAL when the lockres on migration target is
               in DROPPING_REF state

 dlmcommon.h   |   17 +++++++
 dlmdomain.c   |   11 ++++-
 dlmmaster.c   |  124 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 dlmrecovery.c |   32 ++++++++++----
 dlmthread.c   |    7 +++
 5 files changed, 178 insertions(+), 13 deletions(-)

Thanks,
Jiufei Xue