ocfs2/dlm: ignore cleaning the migration mle that is inuse

We have found that migration source will trigger a BUG that the refcount
of mle is already zero before put when the target is down during
migration.  The situation is as follows:

dlm_migrate_lockres
  dlm_add_migration_mle
  dlm_mark_lockres_migrating
  dlm_get_mle_inuse
  <<<<<< Now the refcount of the mle is 2.
  dlm_send_one_lockres and wait for the target to become the
  new master.
  <<<<<< o2hb detect the target down and clean the migration
  mle. Now the refcount is 1.

dlm_migrate_lockres woken, and put the mle twice when found the target
goes down which trigger the BUG with the following message:

  "ERROR: bad mle: ".

Signed-off-by: Jiufei Xue <xuejiufei@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 11 deletions

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 6f0748122117..8b9d483e94a6 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2519,6 +2519,11 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
         spin_lock(&dlm->master_lock);
         ret = dlm_add_migration_mle(dlm, res, mle, &oldmle, name,
                                     namelen, target, dlm->node_num);
+        /* get an extra reference on the mle.
+         * otherwise the assert_master from the new
+         * master will destroy this.
+         */
+        dlm_get_mle_inuse(mle);
         spin_unlock(&dlm->master_lock);
         spin_unlock(&dlm->spinlock);
 
@@ -2554,6 +2559,7 @@ fail:
                 if (mle_added) {
                         dlm_mle_detach_hb_events(dlm, mle);
                         dlm_put_mle(mle);
+                        dlm_put_mle_inuse(mle);
                 } else if (mle) {
                         kmem_cache_free(dlm_mle_cache, mle);
                         mle = NULL;
@@ -2571,17 +2577,6 @@ fail:
          * ensure that all assert_master work is flushed. */
         flush_workqueue(dlm->dlm_worker);
 
-        /* get an extra reference on the mle.
-         * otherwise the assert_master from the new
-         * master will destroy this.
-         * also, make sure that all callers of dlm_get_mle
-         * take both dlm->spinlock and dlm->master_lock */
-        spin_lock(&dlm->spinlock);
-        spin_lock(&dlm->master_lock);
-        dlm_get_mle_inuse(mle);
-        spin_unlock(&dlm->master_lock);
-        spin_unlock(&dlm->spinlock);
-
         /* notify new node and send all lock state */
         /* call send_one_lockres with migration flag.
          * this serves as notice to the target node that a
@@ -3312,6 +3307,15 @@ top:
                             mle->new_master != dead_node)
                                 continue;
 
+                        if (mle->new_master == dead_node && mle->inuse) {
+                                mlog(ML_NOTICE, "%s: target %u died during "
+                                                "migration from %u, the MLE is "
+                                                "still keep used, ignore it!\n",
+                                                dlm->name, dead_node,
+                                                mle->master);
+                                continue;
+                        }
+
                         /* If we have reached this point, this mle needs to be
                          * removed from the list and freed. */
                         dlm_clean_migration_mle(dlm, mle);