directory notification.

directory notification.

[Terje Malmedal]

Hi, 

Modifications of existing files via NFS are not picked up by the
directory notification system.

kernel is 2.4.22, I'm testing with the example program from
/usr/src/linux/Documentation/dnotify.txt

I get notifications on the following: 
nfs-server# echo hello >> existing.file   
nfs-client# echo hello > new.file

But not on this: 
nfs-client# echo hello >> existing.file 

I guess the problem of detecting changes done via NFS is similar to
the problem of multiple hard-links to the same file, which is
documented as not supported.

Is this something that can be fixed, or is it going to be too
difficult to go from NFS-handle and back to the directory it came
from?

-- 
 - Terje
malmedal@usit.uio.no

Re: directory notification.

[Stephen Rothwell]

On Tue, 4 Nov 2003 18:44:29 +0100 Terje Malmedal <terje.malmedal@usit.uio.no> wrote:
>
> Modifications of existing files via NFS are not picked up by the
> directory notification system.
> 
> kernel is 2.4.22, I'm testing with the example program from
> /usr/src/linux/Documentation/dnotify.txt
> 
> I get notifications on the following: 
> nfs-server# echo hello >> existing.file   
> nfs-client# echo hello > new.file
> 
> But not on this: 
> nfs-client# echo hello >> existing.file 
> 
> I guess the problem of detecting changes done via NFS is similar to
> the problem of multiple hard-links to the same file, which is
> documented as not supported.
> 
> Is this something that can be fixed, or is it going to be too
> difficult to go from NFS-handle and back to the directory it came
> from?

Are you running the program that expects notifies on the NFS server or the
client? If on the client, you will never get notifies for modifications
made on the server or other clients.  If on the server, it needs looking
at as you should get the notifies (I think - it has been a while since I
last looked at the NFS server code).

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

Re: directory notification.

[Terje Malmedal]

[Stephen Rothwell]
> On Tue, 4 Nov 2003 18:44:29 +0100 Terje Malmedal <terje.malmedal@usit.uio.no> wrote:
>> 
>> Modifications of existing files via NFS are not picked up by the
>> directory notification system.
>> 
>> kernel is 2.4.22, I'm testing with the example program from
>> /usr/src/linux/Documentation/dnotify.txt
>> 
>> I get notifications on the following: 
>> nfs-server# echo hello >> existing.file   
>> nfs-client# echo hello > new.file
>> 
>> But not on this: 
>> nfs-client# echo hello >> existing.file 
>> 
>> I guess the problem of detecting changes done via NFS is similar to
>> the problem of multiple hard-links to the same file, which is
>> documented as not supported.
>> 
>> Is this something that can be fixed, or is it going to be too
>> difficult to go from NFS-handle and back to the directory it came
>> from?

> Are you running the program that expects notifies on the NFS server or the
> client? 

On the server of course.

> If on the client, you will never get notifies for modifications
> made on the server or other clients.  If on the server, it needs looking
> at as you should get the notifies (I think - it has been a while since I
> last looked at the NFS server code).

It would be very nice if this could be fixed. 

-- 
 - Terje
malmedal@usit.uio.no