+static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
+{
+ struct nameidata *old = current->nameidata;
+ p->stack = p->internal;
+ p->dfd = dfd;
+ p->name = name;
+ p->total_link_count = old ? old->total_link_count : 0;
+ p->saved = old;
+ current->nameidata = p;
+}
+
+static void restore_nameidata(void)
+{
+ struct nameidata *now = current->nameidata, *old = now->saved;
+
+ current->nameidata = old;
+ if (old)
+ old->total_link_count = now->total_link_count;
+ if (now->stack != now->internal) {
+ kfree(now->stack);
+ now->stack = now->internal;
+ }
+}
+
+static int __nd_alloc_stack(struct nameidata *nd)
+{
+ struct saved *p;
+
+ if (nd->flags & LOOKUP_RCU) {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ GFP_ATOMIC);
+ if (unlikely(!p))
+ return -ECHILD;
+ } else {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ GFP_KERNEL);
+ if (unlikely(!p))
+ return -ENOMEM;
+ }
+ memcpy(p, nd->internal, sizeof(nd->internal));
+ nd->stack = p;
+ return 0;
+}
+
+/**
+ * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
+ * @path: nameidate to verify
+ *
+ * Rename can sometimes move a file or directory outside of a bind
+ * mount, path_connected allows those cases to be detected.
+ */
+static bool path_connected(const struct path *path)
+{
+ struct vfsmount *mnt = path->mnt;
+
+ /* Only bind mounts can have disconnected paths */
+ if (mnt->mnt_root == mnt->mnt_sb->s_root)
+ return true;
+
+ return is_subdir(path->dentry, mnt->mnt_root);
+}
+
+static inline int nd_alloc_stack(struct nameidata *nd)
+{
+ if (likely(nd->depth != EMBEDDED_LEVELS))
+ return 0;
+ if (likely(nd->stack != nd->internal))
+ return 0;
+ return __nd_alloc_stack(nd);
+}
+
+static void drop_links(struct nameidata *nd)
+{
+ int i = nd->depth;
+ while (i--) {
+ struct saved *last = nd->stack + i;
+ struct inode *inode = last->inode;
+ if (last->cookie && inode->i_op->put_link) {
+ inode->i_op->put_link(inode, last->cookie);
+ last->cookie = NULL;
+ }
+ }
+}
+
+static void terminate_walk(struct nameidata *nd)
+{
+ drop_links(nd);
+ if (!(nd->flags & LOOKUP_RCU)) {
+ int i;
+ path_put(&nd->path);
+ for (i = 0; i < nd->depth; i++)
+ path_put(&nd->stack[i].link);
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ path_put(&nd->root);
+ nd->root.mnt = NULL;
+ }
+ } else {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ }
+ nd->depth = 0;
+}
+
+/* path_put is needed afterwards regardless of success or failure */
+static bool legitimize_path(struct nameidata *nd,
+ struct path *path, unsigned seq)
+{
+ int res = __legitimize_mnt(path->mnt, nd->m_seq);
+ if (unlikely(res)) {
+ if (res > 0)
+ path->mnt = NULL;
+ path->dentry = NULL;
+ return false;
+ }
+ if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
+ path->dentry = NULL;
+ return false;
+ }
+ return !read_seqcount_retry(&path->dentry->d_seq, seq);
+}
+
+static bool legitimize_links(struct nameidata *nd)
+{
+ int i;
+ for (i = 0; i < nd->depth; i++) {
+ struct saved *last = nd->stack + i;
+ if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
+ drop_links(nd);
+ nd->depth = i + 1;
+ return false;
+ }
+ }
+ return true;
+}
+