Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm...

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

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index fffca9517321c88ee1e0128b864b257c56e2350d..2d48d28e164015668dcc8d04ff72148f07f28e38 100644 (file)
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -592,6 +592,9 @@ int kernfs_add_one(struct kernfs_node *kn)
                goto out_unlock;
 
        ret = -ENOENT;
+       if (parent->flags & KERNFS_EMPTY_DIR)
+               goto out_unlock;
+
        if ((parent->flags & KERNFS_ACTIVATED) && !kernfs_active(parent))
                goto out_unlock;
 
@@ -783,6 +786,38 @@ struct kernfs_node *kernfs_create_dir_ns(struct kernfs_node *parent,
        return ERR_PTR(rc);
 }
 
+/**
+ * kernfs_create_empty_dir - create an always empty directory
+ * @parent: parent in which to create a new directory
+ * @name: name of the new directory
+ *
+ * Returns the created node on success, ERR_PTR() value on failure.
+ */
+struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
+                                           const char *name)
+{
+       struct kernfs_node *kn;
+       int rc;
+
+       /* allocate */
+       kn = kernfs_new_node(parent, name, S_IRUGO|S_IXUGO|S_IFDIR, KERNFS_DIR);
+       if (!kn)
+               return ERR_PTR(-ENOMEM);
+
+       kn->flags |= KERNFS_EMPTY_DIR;
+       kn->dir.root = parent->dir.root;
+       kn->ns = NULL;
+       kn->priv = NULL;
+
+       /* link in */
+       rc = kernfs_add_one(kn);
+       if (!rc)
+               return kn;
+
+       kernfs_put(kn);
+       return ERR_PTR(rc);
+}
+
 static struct dentry *kernfs_iop_lookup(struct inode *dir,
                                        struct dentry *dentry,
                                        unsigned int flags)
@@ -1254,7 +1289,8 @@ int kernfs_rename_ns(struct kernfs_node *kn, struct kernfs_node *new_parent,
        mutex_lock(&kernfs_mutex);
 
        error = -ENOENT;
-       if (!kernfs_active(kn) || !kernfs_active(new_parent))
+       if (!kernfs_active(kn) || !kernfs_active(new_parent) ||
+           (new_parent->flags & KERNFS_EMPTY_DIR))
                goto out;
 
        error = 0;