The patch titled
     Subject: ocfs2/dlm: ignore cleaning the migration mle that is inuse
has been added to the -mm tree.  Its filename is
     ocfs2-dlm-ignore-cleaning-the-migration-mle-that-is-inuse.patch

This patch should soon appear at
    
http://ozlabs.org/~akpm/mmots/broken-out/ocfs2-dlm-ignore-cleaning-the-migration-mle-that-is-inuse.patch
and later at
    
http://ozlabs.org/~akpm/mmotm/broken-out/ocfs2-dlm-ignore-cleaning-the-migration-mle-that-is-inuse.patch

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------------------------------------------------------
From: xuejiufei <xuejiu...@huawei.com>
Subject: 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 <xuejiu...@huawei.com>
Reviewed-by: Joseph Qi <joseph...@huawei.com>
Cc: Mark Fasheh <mfas...@suse.de>
Cc: Joel Becker <jl...@evilplan.org>
Cc: Junxiao Bi <junxiao...@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
---

 fs/ocfs2/dlm/dlmmaster.c |   26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff -puN 
fs/ocfs2/dlm/dlmmaster.c~ocfs2-dlm-ignore-cleaning-the-migration-mle-that-is-inuse
 fs/ocfs2/dlm/dlmmaster.c
--- 
a/fs/ocfs2/dlm/dlmmaster.c~ocfs2-dlm-ignore-cleaning-the-migration-mle-that-is-inuse
+++ a/fs/ocfs2/dlm/dlmmaster.c
@@ -2519,6 +2519,11 @@ static int dlm_migrate_lockres(struct dl
        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);
_

Patches currently in -mm which might be from xuejiu...@huawei.com are

ocfs2-dlm-clear-migration_pending-when-migration-target-goes-down.patch
ocfs2-dlm-fix-a-race-between-purge-and-migratio.patch
ocfs2-dlm-fix-a-race-between-purge-and-migratio-v2.patch
ocfs2-dlm-return-appropriate-value-when-dlm_grab-returns-null.patch
ocfs2-dlm-ignore-cleaning-the-migration-mle-that-is-inuse.patch
ocfs2-extend-transaction-for-ocfs2_remove_rightmost_path-and-ocfs2_update_edge_lengths-before-to-avoid-inconsistency-between-inode-and-et.patch
extend-enough-credits-for-freeing-one-truncate-record-while-replaying-truncate-records.patch

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