[Lsf-pc] [LSF/MM/BPF TOPIC] Enabling change notification for network and cluster fs

[Steve French]

It is common to have read leases on directories but they should not be a
problem with notify

On Sat, Feb 26, 2022, 05:22 Amir Goldstein <amir73il at gmail.com> wrote:

> On Fri, Feb 25, 2022 at 8:11 PM Steve French <smfrench at gmail.com> wrote:
> >
> > > IOW, in general disable all local events and let filesystems decide
> which
> > local events to generate? And locally cached write is one such example?
> >
> > The fs doesn't see cached writes so probably best to still use the common
> > existing code for notification on local writes
> >
>
> I guess SMB protocol does not allow client B to request a NOTIFY on change
> when client A has a directory lease, because requesting NOTIFY requires
> getting a read file handle on the dir?
>
> Effectively, smb client needs to open the remote directory for read in
> order
> to prove that the client has read access to the directory, which is the
> prerequisite for getting directory change notifications.
>
> The local check for permissions is not enough for remote notifications:
>         /* you can only watch an inode if you have read permissions on it
> */
>         error = path_permission(path, MAY_READ);
>
> Thanks,
> Amir.
>