kernfs: implement kernfs_node_from_dentry(), kernfs_root_from_sb() and kernfs_rename()

[firefly-linux-kernel-4.4.55.git] / fs / kernfs / dir.c

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 3cff0a233cd14b4c6767aa9b4ffbae07f3be5adb..42a250f83b98cf1c294be3f4136aa9e837333e50 100644 (file)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -350,6 +350,24 @@ const struct dentry_operations kernfs_dops = {
        .d_release      = kernfs_dop_release,
 };
 
+/**
+ * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
+ * @dentry: the dentry in question
+ *
+ * Return the kernfs_node associated with @dentry.  If @dentry is not a
+ * kernfs one, %NULL is returned.
+ *
+ * While the returned kernfs_node will stay accessible as long as @dentry
+ * is accessible, the returned node can be in any state and the caller is
+ * fully responsible for determining what's accessible.
+ */
+struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
+{
+       if (dentry->d_op == &kernfs_dops)
+               return dentry->d_fsdata;
+       return NULL;
+}
+
 static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
                                             const char *name, umode_t mode,
                                             unsigned flags)