ocfs2: add spinlock protection when dealing with lockres->purge.

when we check/modify lockres->purge, we should with the protection of lockres->spinlock.
in dlm_purge_lockres(), the checking/modifying is not with the protectin.
this patch fixes it.

Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index d490b66ad9d7..98569e86c613 100644
--- a/fs/ocfs2/dlm/dlmthread.c
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -212,14 +212,18 @@ static int dlm_purge_lockres(struct dlm_ctxt *dlm,
                 spin_lock(&dlm->spinlock);
         }
 
+        spin_lock(&res->spinlock);
         if (!list_empty(&res->purge)) {
                 mlog(0, "removing lockres %.*s:%p from purgelist, "
                      "master = %d\n", res->lockname.len, res->lockname.name,
                      res, master);
                 list_del_init(&res->purge);
+                spin_unlock(&res->spinlock);
                 dlm_lockres_put(res);
                 dlm->purge_count--;
-        }
+        } else
+                spin_unlock(&res->spinlock);
+
         __dlm_unhash_lockres(res);
 
         /* lockres is not in the hash now.  drop the flag and wake up