[PATCH 25/73] union-mount: Create d_free_unions() [ver #2]

[David Howells]

From: Valerie Aurora <vaurora@xxxxxxxxxx>

d_free_unions() frees the union stack associated with a directory.

Original-author: Valerie Aurora <vaurora@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---

 fs/union.c |   24 ++++++++++++++++++++++++
 fs/union.h |   10 ++++++++++
 2 files changed, 34 insertions(+), 0 deletions(-)

diff --git a/fs/union.c b/fs/union.c
index c8d7766..77d6a74 100644
--- a/fs/union.c
+++ b/fs/union.c
@@ -19,6 +19,7 @@
 #include <linux/mount.h>
 #include <linux/fs_struct.h>
 #include <linux/slab.h>
+#include <linux/namei.h>
 
 #include "union.h"
 
@@ -36,3 +37,26 @@ static struct union_stack *union_alloc(struct path *topmost)
 
 	return kcalloc(sizeof(struct path), layers, GFP_KERNEL);
 }
+
+/**
+ * d_free_unions - free all unions for this dentry
+ * @dentry: topmost dentry in the union stack to remove
+ *
+ * This must be called when freeing a dentry.
+ */
+void d_free_unions(struct dentry *topmost)
+{
+	struct path *path;
+	unsigned int i, layers = topmost->d_sb->s_union_count;
+
+	if (!IS_DIR_UNIONED(topmost))
+		return;
+
+	for (i = 0; i < layers; i++) {
+		path = union_find_dir(topmost, i);
+		if (path->mnt)
+			path_put(path);
+	}
+	kfree(topmost->d_union_stack);
+	topmost->d_union_stack = NULL;
+}
diff --git a/fs/union.h b/fs/union.h
index f90d037..04a02ec 100644
--- a/fs/union.h
+++ b/fs/union.h
@@ -51,6 +51,13 @@ struct union_stack {
 	struct path u_dirs[0];
 };
 
+static inline bool IS_DIR_UNIONED(struct dentry *dentry)
+{
+	return !!dentry->d_union_stack;
+}
+
+extern void d_free_unions(struct dentry *);
+
 static inline
 struct path *union_find_dir(struct dentry *dentry, unsigned int layer)
 {
@@ -67,4 +74,7 @@ struct path *union_find_dir(struct dentry *dentry, unsigned int layer)
 	return NULL;
 }
 
+static inline bool IS_DIR_UNIONED(struct dentry *dentry) { return false; }
+static inline void d_free_unions(struct dentry *dentry) {}
+
 #endif	/* CONFIG_UNION_MOUNT */

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