ocfs2: give the dlm dirty list a reference on the lockres

Signed-off-by: Kurt Hackel <kurt.hackel@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

2 files changed, 17 insertions, 3 deletions

diff --git a/fs/ocfs2/dlm/dlmcommon.h b/fs/ocfs2/dlm/dlmcommon.h
index 78eccd0951e4..829cc3948804 100644
--- a/fs/ocfs2/dlm/dlmcommon.h
+++ b/fs/ocfs2/dlm/dlmcommon.h
@@ -235,18 +235,26 @@ struct dlm_lock_resource
         struct qstr lockname;
         struct kref      refs;
 
-        /* please keep these next 3 in this order
-         * some funcs want to iterate over all lists */
+        /*
+         * Please keep granted, converting, and blocked in this order,
+         * as some funcs want to iterate over all lists.
+         *
+         * All four lists are protected by the hash's reference.
+         */
         struct list_head granted;
         struct list_head converting;
         struct list_head blocked;
+        struct list_head purge;
 
+        /*
+         * These two lists require you to hold an additional reference
+         * while they are on the list.
+         */
         struct list_head dirty;
         struct list_head recovering; // dlm_recovery_ctxt.resources list
 
         /* unused lock resources have their last_used stamped and are
          * put on a list for the dlm thread to run. */
-        struct list_head purge;
         unsigned long    last_used;
 
         unsigned migration_pending:1;
diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index 76526ea95bb2..610dc76a851b 100644
--- a/fs/ocfs2/dlm/dlmthread.c
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -455,6 +455,8 @@ void __dlm_dirty_lockres(struct dlm_ctxt *dlm, struct dlm_lock_resource *res)
         /* don't shuffle secondary queues */
         if ((res->owner == dlm->node_num) &&
             !(res->state & DLM_LOCK_RES_DIRTY)) {
+                /* ref for dirty_list */
+                dlm_lockres_get(res);
                 list_add_tail(&res->dirty, &dlm->dirty_list);
                 res->state |= DLM_LOCK_RES_DIRTY;
         }
@@ -639,6 +641,8 @@ static int dlm_thread(void *data)
                         list_del_init(&res->dirty);
                         spin_unlock(&res->spinlock);
                         spin_unlock(&dlm->spinlock);
+                        /* Drop dirty_list ref */
+                        dlm_lockres_put(res);
 
                         /* lockres can be re-dirtied/re-added to the
                          * dirty_list in this gap, but that is ok */
@@ -691,6 +695,8 @@ in_progress:
                         /* if the lock was in-progress, stick
                          * it on the back of the list */
                         if (delay) {
+                                /* ref for dirty_list */
+                                dlm_lockres_get(res);
                                 spin_lock(&res->spinlock);
                                 list_add_tail(&res->dirty, &dlm->dirty_list);
                                 res->state |= DLM_LOCK_RES_DIRTY;