[Ocfs2-devel] [PATCH] ocfs2: skip locks in the blocked list

[Xue jiufei <xuejiufei@huawei.com>]

? 2012/8/15 0:03, Sunil Mushran ??:
> On Mon, Aug 13, 2012 at 7:03 PM, Xue jiufei <xuejiufei at huawei.com <mailto:xuejiufei@huawei.com>> wrote:
> 
>       A parallel umount on 4 nodes triggered a bug in dlm_process_recovery_date(). Here?s the situation:
>       Receiving MIG_LOCKRES message, A node processes the locks in migratable lockres. It copys lvb from migratable lockres when processing the first valid lock.
>     If there is a lock in the blocked list with the EX level, it triggers the BUG. Since valid lvbs are set when locks are granted with EX or PR levels, locks in
>     the blocked list cannot have valid lvbs. Therefore I think we should skip the locks in the blocked list.
> 
>     Signed-off-by: Xuejiufei <xuejiufei at huawei.com <mailto:xuejiufei@huawei.com>>
>     ---
>      fs/ocfs2/dlm/dlmrecovery.c |    7 +++++++
>      1 file changed, 7 insertions(+)
> 
>     diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
>     index 01ebfd0..15d81ad 100644
>     --- a/fs/ocfs2/dlm/dlmrecovery.c
>     +++ b/fs/ocfs2/dlm/dlmrecovery.c
>     @@ -1887,6 +1887,13 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
> 
>                     if (ml->type == LKM_NLMODE)
>                             goto skip_lvb;
>     +
>     +               /*
>     +                * If the lock is in the blocked list it can't have a valid lvb,
>     +                * so skip it
>     +                */
>     +               if (ml->list == DLM_BLOCKED_LIST)
>     +                       goto skip_lvb;
> 
>                     if (!dlm_lvb_is_empty(mres->lvb)) {
>                             if (lksb->flags & DLM_LKSB_PUT_LVB) {
>     --
> 
> 
> Looks reasonable. 
> 
> Just wanted to confirm. Did this BUG_ON in dlmrecovery,c get tripped?
> 
> 1903                                 /* otherwise, the node is sending its
> 1904                                  * most recent valid lvb info */
> 1905                                 BUG_ON(ml->type != LKM_EXMODE &&
> 1906                                        ml->type != LKM_PRMODE);
> 

Sorry, I haven't described it clearly.

We trigger the BUG() in dlmrecovery.c:1923. 

Lockres had copyed lvb from previous valid locks and then meet with another lock with the EX level.

1907				if (!dlm_lvb_is_empty(res->lvb) &&
1908 				    (ml->type == LKM_EXMODE ||
1909 				     memcmp(res->lvb, mres->lvb, DLM_LVB_LEN))) {
						......
1923 					BUG();
1924				}