mds: fix potential re-evaluate stray dentry in _unlink_local_finish

If MDS handles cap release before _unlink_local_finish, then when MDS
processes _unlink_local_finish, eval_stray might be re-entered twice,
so this will cause crashing.

Fixes: http://tracker.ceph.com/issues/38263
Signed-off-by: Zhi Zhang <zhangz.david@outlook.com>
(cherry picked from commit 72c93baac64211e9f02fa01e743451bf5d63d7a6)

Conflicts:
	src/mds/MDCache.h : Resolved in notify_stray

diff --git a/src/mds/MDCache.h b/src/mds/MDCache.h
index 6b23ca0781fd69e470706407a2d09226600a793e..04f5b6a55da915b5dd6e4d76355c3a3a057d6838 100644 (file)
--- a/src/mds/MDCache.h
+++ b/src/mds/MDCache.h
@@ -192,6 +192,9 @@ public:
    */
   void notify_stray(CDentry *dn) {
     assert(dn->get_dir()->get_inode()->is_stray());
+    if (dn->state_test(CDentry::STATE_PURGING))
+      return;
+
     stray_manager.eval_stray(dn);
   }