X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=fs%2Fdcache.c;h=2d244227999d151de8f12c423fed5d7faa99d770;hb=df3d0bbcdb2cafa23a70223d806655bd37e64a9b;hp=b949af850cd6bd0c1c60a8d1601454468612ab50;hpb=b3abd80250c13414bc258b53e57242feb159af91;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

diff --git a/fs/dcache.c b/fs/dcache.c
index b949af8..2d24422 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