[Ocfs2-devel] [PATCH] ocfs2/dlm: fix race between dispatched_work and dlm_lockres_grab_inflight_worker

[Ocfs2-devel] [PATCH] ocfs2/dlm: fix race between dispatched_work and dlm_lockres_grab_inflight_worker

[Joseph Qi]

Patch ac4fef4d23ed (ocfs2/dlm: do not purge lockres that is queued for
assert master) may have the following possible race case:
dlm_dispatch_assert_master       dlm_wq
----------------------------------------------------------------------
queue_work(dlm->quedlm_worker,
	&dlm->dispatched_work);
                                 dispatch work,
				 dlm_lockres_drop_inflight_worker
				 *BUG_ON(res->inflight_assert_workers == 0)*
dlm_lockres_grab_inflight_worker
inflight_assert_workers++	

So ensure inflight_assert_workers to be increased first.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Signed-off-by: Xue jiufei <xuejiufei@huawei.com>
---
 fs/ocfs2/dlm/dlmmaster.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 6222b35..fc78237 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -694,14 +694,6 @@ void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
 			res->inflight_assert_workers);
 }

-static void dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
-		struct dlm_lock_resource *res)
-{
-	spin_lock(&res->spinlock);
-	__dlm_lockres_grab_inflight_worker(dlm, res);
-	spin_unlock(&res->spinlock);
-}
-
 static void __dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
 		struct dlm_lock_resource *res)
 {
@@ -1635,6 +1627,7 @@ send_response:
 		}
 		mlog(0, "%u is the owner of %.*s, cleaning everyone else\n",
 			     dlm->node_num, res->lockname.len, res->lockname.name);
+		spin_lock(&res->spinlock);
 		ret = dlm_dispatch_assert_master(dlm, res, 0, request->node_idx,
 						 DLM_ASSERT_MASTER_MLE_CLEANUP);
 		if (ret < 0) {
@@ -1642,7 +1635,8 @@ send_response:
 			response = DLM_MASTER_RESP_ERROR;
 			dlm_lockres_put(res);
 		} else
-			dlm_lockres_grab_inflight_worker(dlm, res);
+			__dlm_lockres_grab_inflight_worker(dlm, res);
+		spin_unlock(&res->spinlock);
 	} else {
 		if (res)
 			dlm_lockres_put(res);
-- 
1.8.4.3