[Ocfs2-devel] [PATCH] ocfs2/dlm: the mig_request could be for recovery
Wengang Wang
wen.gang.wang at oracle.com
Fri Jun 11 03:27:34 PDT 2010
Any comment?
regards,
wengang.
On 10-05-25 21:01, Wengang Wang wrote:
> I hit a bug, it's the BUG_ON() in
>
> 1780 * do not allocate a new lock structure. */
> 1781 if (ml->node == dlm->node_num) {
> 1782 /* MIGRATION ONLY! */
> 1783 BUG_ON(!(mres->flags & DLM_MRES_MIGRATION));
> 1784
> 1785 spin_lock(&res->spinlock);
>
> in dlm_process_recovery_data().
>
> I think it's possible it's a mig_request for recovery in the following case:
>
> 1) Node A and node B have ref on lockres A mastered by node C. So on node C
> the is a lock on behalf of A, lock A, on lockres A.
> 2) For umount, node C is migrating lockres A to node B. the migration mle,
> master being node C, new master being node B, is created and added to mle
> hashtable.
> 3) Node B "down". Node A is the recovery master. On node C, lockres A also become
> the object to recovery because it's during migration and the new master is the
> "down" node B.
> 4) Node C send mig_request request(for recovery) to node A for lockres A including
> lock A.
> 5) receiving the mig_request from node C(for recovery), node A BUG()ed because of
> lock A.
>
> fix:
> removing the BUG_ON() is OK.
>
> Well, I can't reproduce the bug. So didn't test the fix.
>
> Signed-off-by: Wengang Wang <wen.gang.wang at oracle.com>
> ---
> fs/ocfs2/dlm/dlmrecovery.c | 1 -
> 1 files changed, 0 insertions(+), 1 deletions(-)
>
> diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
> index b4f99de..03f17d5 100644
> --- a/fs/ocfs2/dlm/dlmrecovery.c
> +++ b/fs/ocfs2/dlm/dlmrecovery.c
> @@ -1780,7 +1780,6 @@ static int dlm_process_recovery_data(struct dlm_ctxt *dlm,
> * do not allocate a new lock structure. */
> if (ml->node == dlm->node_num) {
> /* MIGRATION ONLY! */
> - BUG_ON(!(mres->flags & DLM_MRES_MIGRATION));
>
> spin_lock(&res->spinlock);
> for (j = DLM_GRANTED_LIST; j <= DLM_BLOCKED_LIST; j++) {
> --
> 1.6.6.1
>
>
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