Re: [PATCH] symlink nesting level change

From: Tim Pepper
Date: Thu Jul 13 2006 - 14:33:38 EST


On 5/3/06, Andrew Morton <akpm@xxxxxxxx> wrote:
On Wed, 3 May 2006 04:08:49 +0100
Al Viro <viro@xxxxxxxxxxxxxxxx> wrote:

> No. It's way past time to bump it to 8. Everyone had been warned - for
> months now.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ----
> --- a/include/linux/namei.h 2006-03-31 20:08:42.000000000 -0500
> +++ b/include/linux/namei.h 2006-05-02 23:06:46.000000000 -0400
> @@ -11,7 +11,7 @@
> struct file *file;
> };
>
> -enum { MAX_NESTED_LINKS = 5 };
> +enum { MAX_NESTED_LINKS = 8 };
>
> struct nameidata {
> struct dentry *dentry;

It's a non-back-compatible change which means that people will install
2.6.18+, will set stuff up which uses more that five nested links and some
will discover that they can no longer run their software on older kernels.

It'll only hurt a very small number of people, but for those people, it
will hurt a lot. And I can't really think of anything we can do to help
them, apart from making the new behaviour runtime-controllable, defaulting
to "off", but add a once-off printk when we hit MAX_NESTED_LINKS, pointing
them at a document which tells them how to turn on the new behaviour and
which explains the problems. Which sucks.

But I guess as major distros are 2.6.16-based, this is a good time to make
this change.

Doesn't look like this ended up in 2.6.18-rc nor -mm. The email
thread in May was tending towards finally bumping it. Major distros
already have it at 8 for a long time. Is there any reason left (aside
now from possibly waiting until 2.6.19's window?) to wait?


Tim
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