ocfs2/dlm: do not purge lockres that is queued for assert master

When workqueue is delayed, it may occur that a lockres is purged while it
is still queued for master assert.  it may trigger BUG() as follows.

N1                                         N2
dlm_get_lockres()
->dlm_do_master_requery
                                  is the master of lockres,
                                  so queue assert_master work

                                  dlm_thread() start running
                                  and purge the lockres

                                  dlm_assert_master_worker()
                                  send assert master message
                                  to other nodes
receiving the assert_master
message, set master to N2

dlmlock_remote() send create_lock message to N2, but receive DLM_IVLOCKID,
if it is RECOVERY lockres, it triggers the BUG().

Another BUG() is triggered when N3 become the new master and send
assert_master to N1, N1 will trigger the BUG() because owner doesn't
match.  So we should not purge lockres when it is queued for assert
master.

Signed-off-by: joyce.xue <xuejiufei@huawei.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 55 insertions, 6 deletions

diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index a106b3f2b22a..fae17c640df3 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -331,6 +331,7 @@ struct dlm_lock_resource
         u16 state;
         char lvb[DLM_LVB_LEN];
         unsigned int inflight_locks;
+        unsigned int inflight_assert_workers;
         unsigned long refmap[BITS_TO_LONGS(O2NM_MAX_NODES)];
 };
 
@@ -910,6 +911,9 @@ void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
 void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,
                                    struct dlm_lock_resource *res);
 
+void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
+                struct dlm_lock_resource *res);
+
 void dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
 void dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
 void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock);
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 4f4b00e173f2..82abf0cc9a12 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -581,6 +581,7 @@ static void dlm_init_lockres(struct dlm_ctxt *dlm,
         atomic_set(&res->asts_reserved, 0);
         res->migration_pending = 0;
         res->inflight_locks = 0;
+        res->inflight_assert_workers = 0;
 
         res->dlm = dlm;
 
@@ -683,6 +684,43 @@ void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,
         wake_up(&res->wq);
 }
 
+void __dlm_lockres_grab_inflight_worker(struct dlm_ctxt *dlm,
+                struct dlm_lock_resource *res)
+{
+        assert_spin_locked(&res->spinlock);
+        res->inflight_assert_workers++;
+        mlog(0, "%s:%.*s: inflight assert worker++: now %u\n",
+                        dlm->name, res->lockname.len, res->lockname.name,
+                        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)
+{
+        assert_spin_locked(&res->spinlock);
+        BUG_ON(res->inflight_assert_workers == 0);
+        res->inflight_assert_workers--;
+        mlog(0, "%s:%.*s: inflight assert worker--: now %u\n",
+                        dlm->name, res->lockname.len, res->lockname.name,
+                        res->inflight_assert_workers);
+}
+
+static void dlm_lockres_drop_inflight_worker(struct dlm_ctxt *dlm,
+                struct dlm_lock_resource *res)
+{
+        spin_lock(&res->spinlock);
+        __dlm_lockres_drop_inflight_worker(dlm, res);
+        spin_unlock(&res->spinlock);
+}
+
 /*
  * lookup a lock resource by name.
  * may already exist in the hashtable.
@@ -1603,7 +1641,8 @@ send_response:
                         mlog(ML_ERROR, "failed to dispatch assert master work\n");
                         response = DLM_MASTER_RESP_ERROR;
                         dlm_lockres_put(res);
-                }
+                } else
+                        dlm_lockres_grab_inflight_worker(dlm, res);
         } else {
                 if (res)
                         dlm_lockres_put(res);
@@ -2118,6 +2157,8 @@ static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
         dlm_lockres_release_ast(dlm, res);
 
 put:
+        dlm_lockres_drop_inflight_worker(dlm, res);
+
         dlm_lockres_put(res);
 
         mlog(0, "finished with dlm_assert_master_worker\n");
diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 5de019437ea5..45067faf5695 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -1708,7 +1708,8 @@ int dlm_master_requery_handler(struct o2net_msg *msg, u32 len, void *data,
                                 mlog_errno(-ENOMEM);
                                 /* retry!? */
                                 BUG();
-                        }
+                        } else
+                                __dlm_lockres_grab_inflight_worker(dlm, res);
                 } else /* put.. incase we are not the master */
                         dlm_lockres_put(res);
                 spin_unlock(&res->spinlock);
diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index cf53a822f07f..69aac6f088ad 100644
--- a/fs/ocfs2/dlm/dlmthread.c
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -259,11 +259,14 @@ static void dlm_run_purge_list(struct dlm_ctxt *dlm,
                  * refs on it. */
                 unused = __dlm_lockres_unused(lockres);
                 if (!unused ||
-                    (lockres->state & DLM_LOCK_RES_MIGRATING)) {
+                    (lockres->state & DLM_LOCK_RES_MIGRATING) ||
+                    (lockres->inflight_assert_workers != 0)) {
                         mlog(0, "%s: res %.*s is in use or being remastered, "
-                             "used %d, state %d\n", dlm->name,
-                             lockres->lockname.len, lockres->lockname.name,
-                             !unused, lockres->state);
+                             "used %d, state %d, assert master workers %u\n",
+                             dlm->name, lockres->lockname.len,
+                             lockres->lockname.name,
+                             !unused, lockres->state,
+                             lockres->inflight_assert_workers);
                         list_move_tail(&lockres->purge, &dlm->purge_list);
                         spin_unlock(&lockres->spinlock);
                         continue;