From: Valerie Aurora <vaurora@xxxxxxxxxx>
union_add_dir() fills out the union stack for the topmost dentry with
the path of the directory in this layer of the union.
Signed-off-by: Valerie Aurora <valerie.aurora@xxxxxxxxx>
---
fs/union.c | 28 ++++++++++++++++++++++++++++
fs/union.h | 2 ++
2 files changed, 30 insertions(+), 0 deletions(-)
diff --git a/fs/union.c b/fs/union.c
index a191bef..45552f8 100644
--- a/fs/union.c
+++ b/fs/union.c
@@ -65,3 +65,31 @@ void d_free_unions(struct dentry *topmost)
kfree(topmost->d_union_stack);
topmost->d_union_stack = NULL;
}
+
+/**
+ * union_add_dir - Add another layer to a unioned directory
+ *
+ * @topmost - topmost directory
+ * @lower - directory in the current layer
+ * @layer - index of layer to add this at
+ *
+ * @layer counts starting at 0 for the dir below the topmost dir.
+ * Must take a reference to @lower (call path_get()) before calling
+ * this function.
+ */
+
+int union_add_dir(struct path *topmost, struct path *lower,
+ unsigned int layer)
+{
+ struct path *path;
+ struct dentry *dentry = topmost->dentry;
+ BUG_ON(layer >= dentry->d_sb->s_union_count);
+
+ if (!dentry->d_union_stack)
+ dentry->d_union_stack = union_alloc(topmost);
+ if (!dentry->d_union_stack)
+ return -ENOMEM;
+ path = union_find_dir(dentry, layer);
+ *path = *lower;
+ return 0;
+}
diff --git a/fs/union.h b/fs/union.h
index 353f78d..bd03d67 100644
--- a/fs/union.h
+++ b/fs/union.h
@@ -52,6 +52,7 @@ struct union_stack {
#define IS_DIR_UNIONED(dentry) ((dentry)->d_union_stack)
extern void d_free_unions(struct dentry *);
+extern int union_add_dir(struct path *, struct path *, unsigned int);
static inline struct path *union_find_dir(struct dentry *dentry,
unsigned int layer) {
@@ -64,6 +65,7 @@ static inline struct path *union_find_dir(struct dentry *dentry,
#define IS_DIR_UNIONED(x) (0)
#define d_free_unions(x) do { } while (0)
+#define union_add_dir(x, y, z) ({ BUG(); (0); })
#define union_find_dir(x, y) ({ BUG(); (NULL); })
#endif /* CONFIG_UNION_MOUNT */
--
1.7.0.4
--
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