1 files changed, 15 insertions, 0 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index b949af850cd6..2d244227999d 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -611,8 +611,23 @@ static inline void __dget(struct dentry *dentry)
 
 struct dentry *dget_parent(struct dentry *dentry)
 {
+        int gotref;
         struct dentry *ret;
 
+        /*
+         * Do optimistic parent lookup without any
+         * locking.
+         */
+        rcu_read_lock();
+        ret = ACCESS_ONCE(dentry->d_parent);
+        gotref = lockref_get_not_zero(&ret->d_lockref);
+        rcu_read_unlock();
+        if (likely(gotref)) {
+                if (likely(ret == ACCESS_ONCE(dentry->d_parent)))
+                        return ret;
+                dput(ret);
+        }
+
 repeat:
         /*
          * Don't need rcu_dereference because we re-check it was correct under