Yeah, Andy is right that we should *not* make "write()" have side effects.
Use it to queue things by all means, but not "do" things. Not unless
there's a very sane security model.
On Tue, Jul 10, 2018 at 4:59 PM Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
> I think the right solution is one of:
>
> (a) Pass a netlink-formatted blob to fsopen() and do the whole thing in one syscall. I don’t mean using netlink sockets — just the nlattr format. Or you could use a different format. The part that matters is using just one syscall to do the whole thing.
Please no. Not another nasty marshalling thing.
> (b) Keep the current structure but use a new syscall instead of write().
>
> (c) Keep using write() but literally just buffer the data. Then have a new syscall to commit it. In other words, replace “x” with a syscall and call all the fs_context_operations helpers in that context instead of from write().
But yeah, b-or-c sounds fine.
Linus
