---

yaml
---
r: 234236
b: refs/heads/master
c: c826cb7
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 76ca07832842100b14a31ad8996dab7b0c28aa42
+refs/heads/master: c826cb7dfce80512c26c984350077a25046bd215

trunk/fs/dcache.c

@@ -1011,6 +1011,34 @@ void shrink_dcache_for_umount(struct super_block *sb)
 	}
 }
 
+/*
+ * This tries to ascend one level of parenthood, but
+ * we can race with renaming, so we need to re-check
+ * the parenthood after dropping the lock and check
+ * that the sequence number still matches.
+ */
+static struct dentry *try_to_ascend(struct dentry *old, int locked, unsigned seq)
+{
+	struct dentry *new = old->d_parent;
+
+	rcu_read_lock();
+	spin_unlock(&old->d_lock);
+	spin_lock(&new->d_lock);
+
+	/*
+	 * might go back up the wrong parent if we have had a rename
+	 * or deletion
+	 */
+	if (new != old->d_parent ||
+		 (!locked && read_seqretry(&rename_lock, seq))) {
+		spin_unlock(&new->d_lock);
+		new = NULL;
+	}
+	rcu_read_unlock();
+	return new;
+}
+
+
 /*
  * Search for at least 1 mount point in the dentry's subdirs.
  * We descend to the next level whenever the d_subdirs
@@ -1066,24 +1094,10 @@ int have_submounts(struct dentry *parent)
 	 * All done at this level ... ascend and resume the search.
 	 */
 	if (this_parent != parent) {
-		struct dentry *tmp;
-		struct dentry *child;
-
-		tmp = this_parent->d_parent;
-		rcu_read_lock();
-		spin_unlock(&this_parent->d_lock);
-		child = this_parent;
-		this_parent = tmp;
-		spin_lock(&this_parent->d_lock);
-		/* might go back up the wrong parent if we have had a rename
-		 * or deletion */
-		if (this_parent != child->d_parent ||
-			 (!locked && read_seqretry(&rename_lock, seq))) {
-			spin_unlock(&this_parent->d_lock);
-			rcu_read_unlock();
+		struct dentry *child = this_parent;
+		this_parent = try_to_ascend(this_parent, locked, seq);
+		if (!this_parent)
 			goto rename_retry;
-		}
-		rcu_read_unlock();
 		next = child->d_u.d_child.next;
 		goto resume;
 	}
@@ -1181,24 +1195,10 @@ static int select_parent(struct dentry * parent)
 	 * All done at this level ... ascend and resume the search.
 	 */
 	if (this_parent != parent) {
-		struct dentry *tmp;
-		struct dentry *child;
-
-		tmp = this_parent->d_parent;
-		rcu_read_lock();
-		spin_unlock(&this_parent->d_lock);
-		child = this_parent;
-		this_parent = tmp;
-		spin_lock(&this_parent->d_lock);
-		/* might go back up the wrong parent if we have had a rename
-		 * or deletion */
-		if (this_parent != child->d_parent ||
-			(!locked && read_seqretry(&rename_lock, seq))) {
-			spin_unlock(&this_parent->d_lock);
-			rcu_read_unlock();
+		struct dentry *child = this_parent;
+		this_parent = try_to_ascend(this_parent, locked, seq);
+		if (!this_parent)
 			goto rename_retry;
-		}
-		rcu_read_unlock();
 		next = child->d_u.d_child.next;
 		goto resume;
 	}
@@ -2942,28 +2942,14 @@ void d_genocide(struct dentry *root)
 		spin_unlock(&dentry->d_lock);
 	}
 	if (this_parent != root) {
-		struct dentry *tmp;
-		struct dentry *child;
-
-		tmp = this_parent->d_parent;
+		struct dentry *child = this_parent;
 		if (!(this_parent->d_flags & DCACHE_GENOCIDE)) {
 			this_parent->d_flags |= DCACHE_GENOCIDE;
 			this_parent->d_count--;
 		}
-		rcu_read_lock();
-		spin_unlock(&this_parent->d_lock);
-		child = this_parent;
-		this_parent = tmp;
-		spin_lock(&this_parent->d_lock);
-		/* might go back up the wrong parent if we have had a rename
-		 * or deletion */
-		if (this_parent != child->d_parent ||
-			 (!locked && read_seqretry(&rename_lock, seq))) {
-			spin_unlock(&this_parent->d_lock);
-			rcu_read_unlock();
+		this_parent = try_to_ascend(this_parent, locked, seq);
+		if (!this_parent)
 			goto rename_retry;
-		}
-		rcu_read_unlock();
 		next = child->d_u.d_child.next;
 		goto resume;
 	}