[Linux-cluster] [RFC] Read access to /config/dlm/<cluster>/comms/<comm>/addr

[David Teigland]

On Thu, Jun 09, 2011 at 05:55:29PM +0900, Masatake YAMATO wrote:
> Hi,
> 
> I've found /config/dlm/<cluster>/comms/<comm>/addr is readable 
> (in meaning of ls -l) but no handler(comm_addr_read) is defined in 
> dlm/fs/dlm/config.c.
> 
> If cat command works fine with /config/dlm/<cluster>/comms/<comm>/addr,
> it will be nice to understand the status of dlm. So I'm thinking about
> writing a patch.
> 
> But after reading the source code, I've found its difficulties;
> /config/dlm/<cluster>/comms/<comm>/addr holds 'struct
> sockaddr_storage'.

Another problem is that you can write multiple addr's to that file
sequentially when using SCTP, so which do you get when you read it?

>     3. Make /config/dlm/<cluster>/comms/<comm>/addr unreadable (in meaning of ls -l)
> 
>        e.g.
>        # ls -l /config/dlm/<cluster>/comms/<comm>/addr
>        --w-------. 1 root root 4096 Jun  9 08:51 /config/dlm/<cluster>/comms/<comm>/addr
> 
>        Advantage: easy to implement.
>        Disadvantage: no way to know the value of node addr of dlm view.

I suggest this.  If you want a way to read them, I'd add a new readonly
file addr_list,

# cat /config/dlm/<cluster>/comms/<comm>/addr_list
AF_INET 192.168.151.1
AF_INET 192.168.151.2

Dave