From: ronnie sahlberg <ronniesahlberg@gmail.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Steve French <smfrench@gmail.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
CIFS <linux-cifs@vger.kernel.org>,
samba-technical <samba-technical@lists.samba.org>,
Jan Kara <jack@suse.cz>, Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: [LFS/MM TOPIC] Enabling file and directory change notification for network and cluster file systems
Date: Tue, 21 Jan 2020 18:30:46 +1000 [thread overview]
Message-ID: <CAN05THQeUs1ksOv5sRTx7Dvr0=WKxSguw+gWpw2KpX3byEJagw@mail.gmail.com> (raw)
In-Reply-To: <CAOQ4uxipauh1UXHSFt=WsiaDexqecjm4eDkVfnQXN8eYofdg2A@mail.gmail.com>
On Tue, Jan 21, 2020 at 5:48 PM Amir Goldstein <amir73il@gmail.com> wrote:
>
> On Tue, Jan 21, 2020 at 5:55 AM Steve French <smfrench@gmail.com> wrote:
> >
> > Currently the inotify interface in the kernel can only be used for
> > local file systems (unlike the previous change notify API used years
> > ago, and the change notify interface in Windows and other OS which is
> > primarily of interest for network file systems).
> >
> > I wanted to discuss the VFS changes needed to allow inotify requests
> > to be passed into file systems so network and cluster file systems (as
> > an example in the SMB3 case this simply means sending a
> > SMB3_CHANGE_NOTIFY request to the server, whether Samba or Cloud
> > (Azure) or Mac or Windows or Network Appliance - all support the API
> > on the server side, the problem is that the network or cluster fs
> > client isn't told about the request to wait on the inotify event).
> > Although user space tools can use file system specific ioctls to wait
> > on events, it is obviously preferable to allow network and cluster
> > file systems to wait on events using the calls which current Linux
> > GUIs use.
> >
> > This would allow gnome file manager GUI for example to be
> > automatically updated when a file is added to an open directory window
> > from another remote client.
> >
> > It would also fix the embarrassing problem noted in the inotify man page:
> >
> > "Inotify reports only events that a user-space program triggers
> > through the filesystem
> > API. As a result, it does not catch remote events that occur
> > on network filesystems."
> >
> > but that is precisely the types of notifications that are most useful
> > ... users often are aware of updates to local directories from the
> > same system, but ... automatic notifications that allow GUIs to be
> > updated on changes from **other** clients is of more value (and this
> > is exactly what the equivalent API allows on other OS).
> >
> > The changes to the Linux VFS are small.
> >
> >
>
> Miklos has already posted an RFC patch:
> https://lore.kernel.org/linux-fsdevel/20190507085707.GD30899@veci.piliscsaba.redhat.com/
>
> Did you try it?
>
> You also did not answer Miklos' question:
> does the smb protocol support whole filesystem (or subtree) notifications?
> (or just per-directory notifications)?
SMB can do both. There is a flag that specifies if you want to just
get notified about the directory itself
or whether you want notifications from the whole subtree.
>
> Thanks,
> Amir.
next prev parent reply other threads:[~2020-01-21 8:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-21 3:55 [LFS/MM TOPIC] Enabling file and directory change notification for network and cluster file systems Steve French
2020-01-21 7:47 ` Amir Goldstein
2020-01-21 7:49 ` Amir Goldstein
2020-01-21 8:30 ` ronnie sahlberg [this message]
2020-01-21 9:43 ` Amir Goldstein
2020-01-21 10:02 ` ronnie sahlberg
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