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	Fri, 13 Feb 2026 23:41:47 +0000
Date: Fri, 13 Feb 2026 23:41:47 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Askar Safin <safinaskar@gmail.com>, christian@brauner.io,
	cyphar@cyphar.com, jack@suse.cz, linux-fsdevel@vger.kernel.org,
	torvalds@linux-foundation.org, werner@almesberger.net
Subject: Re: [RFC] pivot_root(2) races
Message-ID: <20260213234147.GS3183987@ZenIV>
References: <1FC2FB1F-BDA5-472D-A7DB-D146F6F75B16@zytor.com>
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Sender: Al Viro <viro@ftp.linux.org.uk>

On Fri, Feb 13, 2026 at 03:00:49PM -0800, H. Peter Anvin wrote:

> Incidentally, how is . treated?

Explicit no-op at any point of pathname.  ".." is
	while dentry == root(mount) && (mount,dentry) != nd->root
		(mount,dentry) = under(mount, dentry)
	if (mount,dentry) != nd->root
		dentry = parent(dentry)
	step_into(dentry)
and crossing into overmounts (if any) happens in step_into().

See handle_dots() and its callers...