linux-kernel - Re: [PATCH 00/32] VFS based Union Mount (V3)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090519131055.GQ16526@bolzano.suse.de>
Date:	Tue, 19 May 2009 15:10:55 +0200
From:	Jan Blunck <jblunck@...e.de>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Miklos Szeredi <miklos@...redi.hu>, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, viro@...iv.linux.org.uk,
	bharata@...ibm.com, dwmw2@...radead.org, mszeredi@...e.cz,
	vaurora@...hat.com
Subject: Re: [PATCH 00/32] VFS based Union Mount (V3)

On Tue, May 19, Arnd Bergmann wrote:

> 
> So what would go wrong if you only made them persistent for writable file
> systems, but allowed fallthrough dentries to be discarded for read-only
> file systems? As long as the lower layers don't change, you should still
> be able to reconstruct the same dentries every time you do a readdir, right?
> 

This can work if you do this when the last file descriptor on the directory is
closed. I have a similar patch around for tmpfs readdir (the SLES8 glibc is
seeking on readdir, so it broke some of our build servers that use tmpfs).

One idea would be to separate the "fallthru in tmpfs" handling into its own
library so that it can be shared by filesystems. This would become something
similar to the On-Disk-Format (ODF) approach that Erez Zadok followed with
UnionFS.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/