follow_dotdot(): be lazy about changing nd->path (165200d6) · Commits · 戴 / test

Change nd->path only after the loop is done and only in case we hadn't ended up finding ourselves in root. Same for NO_XDEV check. That separates the "check how far back do we need to go through the mount stack" logics from the rest of .. traversal. NOTE: path_get/path_put introduced here are temporary. They will go away later in the series. Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -1748,16 +1748,24 @@ static struct dentry follow_dotdot(struct nameidata nd,
		if (path_equal(&nd->path, &nd->root))
		goto in_root;
		if (unlikely(nd->path.dentry == nd->path.mnt->mnt_root)) {
		struct path path = nd->path;
		path_get(&path);
		while (1) {
		if (!follow_up(&nd->path))
		if (!follow_up(&path)) {
		path_put(&path);
		goto in_root;
		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
		return ERR_PTR(-EXDEV);
		if (path_equal(&nd->path, &nd->root))
		}
		if (path_equal(&path, &nd->root)) {
		path_put(&path);
		goto in_root;
		if (nd->path.dentry != nd->path.mnt->mnt_root)
		}
		if (path.dentry != nd->path.mnt->mnt_root)
		break;
		}
		path_put(&nd->path);
		nd->path = path;
		if (unlikely(nd->flags & LOOKUP_NO_XDEV))
		return ERR_PTR(-EXDEV);
		}
		/* rare case of legitimate dget_parent()... */
		parent = dget_parent(nd->path.dentry);

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