linux-ext4 - Re: tune2fs and setting noatime as a default mount options

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]

Date:	Mon, 1 Sep 2014 14:23:46 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	"Theodore Ts'o" <tytso@....edu>
Cc:	Eric Sandeen <sandeen@...hat.com>,
	Tomasz Chmielewski <mangoo@...g.org>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>
Subject: Re: tune2fs and setting noatime as a default mount options

On Fri, Aug 29, 2014 at 3:56 PM, Theodore Ts'o <tytso@....edu> wrote:
> On Fri, Aug 29, 2014 at 10:33:05AM -0500, Eric Sandeen wrote:
>>
>> > Is there a reason why noatime can't be set as a default mount option? Thinking of all these USB connected devices where it would be handy.
>>
>> I haven't looked, but I'm guessing it's because noatime is a
>> vfs-level switch, and by the time the ext4 superblock is getting
>> read and processed during mount, that chance has passed.
>
> Yes, and this is also the cause of this user complaint/bug:
>
>         https://bugzilla.kernel.org/show_bug.cgi?id=61601
>
> There was some discussion at the kernel summit by Andy Lutomirski to
> create new mount system call with sane parsing, and Al Viro wasn't
> totally against that idea.  If we do go forward with some of the ideas
> that was tossed about, this would be something else that would be a
> nice thing to fix at the same time.
>
> The whole distinction between VFS-level mount options (which are
> parsed in userspace and passed down into the kernel using bits in a
> bitfield) and file system-level mount options (which is parsed by the
> kernel and passed in from userspace as a string) is just nasty.
>
> What I would suggest is that all mount options would be passed all the
> way down to the file system, and then there would be a library
> function to handle common VFS-level mount options that would be called
> by the file system's mount option handling code.
>

To clarify: do you mean that per-superblock options would all be
strings and would all get passed down to the fs?  If so, I like it.  I
think that whatever corresponds to MNT_READONLY shouldn't be passed
down to the filesystem or necessarily specified when loading the
filesystem at all.  But MNT_READONLY is a very different thing than
"ro".

--Andy
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html