сб, 2 февр. 2019 г. в 10:13, Pavel Shilovsky <piastryyy@xxxxxxxxx>:
>
> сб, 2 февр. 2019 г. в 03:33, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>:
> >
> > On Wed, Jan 30, 2019 at 04:07:30PM -0800, Pavel Shilovsky wrote:
> > > Commit 28eb24ff75c5 ("cifs: Always resolve hostname before reconnecting").
> > >
> > > In case a hostname resolves to a different IP address (e.g. long
> > > running mounts), make sure to resolve it every time prior to calling
> > > generic_ip_connect() in reconnect.
> > >
> > > This patch needs user space changes of cifs.upcall that set a timeout
> > > value for the "dns_resolver" key.
> >
> > Wait, you are requiring userspace to upgrade tools to support this? And
> > you think that will happen to all systems running older kernels?
> >
> > This really feels like a new feature being added, what bug is this
> > fixing that requires it to be backported to all of the stable kernel
> > trees?
>
> Let's me describe what is going to happen without upgrade of the
> userspace tools. The 1st reconnect will cause proper resolving of DNS
> name and storing this name into the cache. All subsequent reconnects
> will use the value stored in the cache and do not attempt to resolve
> this DNS name. That means the fix will help partially but doesn't
> break anything.
>
> Once the userspace tools are upgraded, the cached DNS name will expire
> in 10 min, so every reconnect routine happening after that will use
> new IP. So, Linux distros will fully benefit from the patch once they
> upgrade the userspace tools but they do not need to synchronize
> updates of the kernel and the tools.
>
> The diff has been generated against the newest kernel but I checked
> that it cherry-picks to at least 4.4.y (and probably older ones).
>
Adding Steve to comment on that.
--
Best regards,
Pavel Shilovsky
