Re: [9fans] afid and fd, mapping from user space

[Russ Cox <russcox@gmail.com>]

As long as you don't use it for such things (i.e. use it for a real file
system and don't depend on atomic stuff like locks)
I don't see a problem.  I used it in 3e for quite a while and never
had any problems.  I had to use special bindings to make sure
I didn't try to deliver mail over it, but other than that it was great.

Russ


On 7/6/05, rog@vitanuova.com <rog@vitanuova.com> wrote:
> > I am porting Recover to 4e. Recover is a filesystem which speaks
> > 9P with two ends, a server and a client. When a connection falls down
> > it pushes the state and restarts the pending requests, so you don't
> > see a hung channel any more if your connection falls down.
> 
> i did something like this for inferno, but couldn't work out what was
> the best thing to do about non-idempotent 9p transactions: if the
> connection is lost before the reply to such a transaction is received,
> what is the correct course of action?  the client can't know whether the
> transaction has actually taken place on the server.
> 
> examples of such requests:
> 
>         create
>         wstat (rename)
>         write to an append-only file
>         any operation on a non-standard filesystem (e.g. writing a ctl file)
> 
> problems arising from this kind of thing will be
> rare, but all the more insidious when they do actually happen.
> 
> in the end, i decided to make such requests yield Rerror("operation possibly failed"),
> but i have a niggling feeling that the whole approach is wrong.
> 
> thoughts?
> 
>