On 09/24/2015 11:14 AM, Joseph Qi wrote:
> There is a race window between dlmconvert_remote and
> dlm_move_lockres_to_recovery_list, which will cause a lock with
> OCFS2_LOCK_BUSY in grant list, thus system hangs.
>
> dlmconvert_remote
> {
> spin_lock(&res->spinlock);
> list_move_tail(&lock->list, &res->converting);
> lock->convert_pending = 1;
> spin_unlock(&res->spinlock);
>
> status = dlm_send_remote_convert_request();
> >>>>>> race window, master has queued ast and return DLM_NORMAL,
> and then down before sending ast.
> this node detects master down and calls
> dlm_move_lockres_to_recovery_list, which will revert the
> lock to grant list.
> Then OCFS2_LOCK_BUSY won't be cleared as new master won't
> send ast any more because it thinks already be authorized.
How this race windowed fixed?
the process have sent convert request to master node successfully(return
value DLM_NORMAL) then wait on LOCK_BUSY, then when master node panic
before send out ast, dlm_move_lockres_to_recovery_list() move the lock
to grant list. Ast never come.
Thanks,
Junxiao.
>
> spin_lock(&res->spinlock);
> lock->convert_pending = 0;
> if (status != DLM_NORMAL)
> dlm_revert_pending_convert(res, lock);
> spin_unlock(&res->spinlock);
> }
>
> In this case, check if res->state has DLM_LOCK_RES_RECOVERING bit set
> (res is still in recovering) or res master changed (new master has
> finished recovery), reset the status to DLM_RECOVERING, then it will
> retry convert.
>
> Signed-off-by: Joseph Qi <joseph...@huawei.com>
> Reported-by: Yiwen Jiang <jiangyi...@huawei.com>
> Cc: <sta...@vger.kernel.org>
> ---
> fs/ocfs2/dlm/dlmconvert.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ocfs2/dlm/dlmconvert.c b/fs/ocfs2/dlm/dlmconvert.c
> index e36d63f..9e6116e 100644
> --- a/fs/ocfs2/dlm/dlmconvert.c
> +++ b/fs/ocfs2/dlm/dlmconvert.c
> @@ -262,6 +262,7 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
> struct dlm_lock *lock, int flags, int type)
> {
> enum dlm_status status;
> + u8 old_owner = res->owner;
>
> mlog(0, "type=%d, convert_type=%d, busy=%d\n", lock->ml.type,
> lock->ml.convert_type, res->state & DLM_LOCK_RES_IN_PROGRESS);
> @@ -316,11 +317,19 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
> spin_lock(&res->spinlock);
> res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
> lock->convert_pending = 0;
> - /* if it failed, move it back to granted queue */
> + /* if it failed, move it back to granted queue.
> + * if master returns DLM_NORMAL and then down before sending ast,
> + * it may have already been moved to granted queue, reset to
> + * DLM_RECOVERING and retry convert */
> if (status != DLM_NORMAL) {
> if (status != DLM_NOTQUEUED)
> dlm_error(status);
> dlm_revert_pending_convert(res, lock);
> + } else if ((res->state & DLM_LOCK_RES_RECOVERING) ||
> + (old_owner != res->owner)) {
> + mlog(0, "res %.*s is in recovering or has been recovered.\n",
> + res->lockname.len, res->lockname.name);
> + status = DLM_RECOVERING;
> }
> bail:
> spin_unlock(&res->spinlock);
>
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel
