Re: [PATCH 2/2] ntfs3: remove warning

[Johan Hovold <johan@kernel.org>]

On Mon, Apr 15, 2024 at 08:23:46AM -0700, Linus Torvalds wrote:
> On Mon, 15 Apr 2024 at 07:16, Christian Brauner <brauner@kernel.org> wrote:
> >
> > (1) Since the ntfs3 driver is supposed to serve as a drop-in replacement
> >     for the legacy ntfs driver we should to it the same way we did it
> >     for ext3 and ext4 where ext4 registers itself also for the ext3
> >     driver. In other words, we would register ntfs3 as ntfs3 filesystem
> >     type and as legacy ntfs filesystem type.
> 
> I think that if just registering it under the same name solves the
> immediate issue, that's the one we should just go for.

I also tend to agree, but...

> >     To make it fully compatible
> >     we also need to make sure it's persistently mounted read-only.
> 
> My reaction to that is "only if it turns out we really need to".
> 
> It sounds unlikely that somebody has an old ntfs setup and then tries
> to mount things rw which didn't use to work and things go sideways if
> that then suddenly works.
> 
> But "unlikely" isn't "impossible", of course - it's just that I'd
> suggest we actually wait for that report to happen and ask what the
> heck they were doing and why they were doing that...

I think the "ntfs" alias must always be mounted read-only because you
can currently have an fstab entry which does not specify "ro" and this
mount would suddenly become writeable when updating to 6.9 (possibly by
a non-privileged user, etc).

We also need to do something about the ntfs3 driver spamming the logs
about broken corrections also when mounted read-only even if it doesn't
eat your filesystem then.

And it seems write-support should be disabled in the driver by default
until someone has tracked down why listing a directory can currently
corrupt your filesystem.

Johan