Re: [RFC][PATCH] get rid of the use of set_fs() (by way of kernel_recvmsg()) in sunrpc

[Christoph Hellwig]

> 	We could turn ->msg_control/->msg_controllen into another
> iov_iter, but seeing that we never do scatter-gather for those
> IMO that would be a massive overkill.  A flag controlling whether
> ->msg_control is kernel or userland pointer would do, especially
> since we already have a flag for "do we want a native or compat
> layout for cmsg" in there.

While your current hack seems like a nice short term improvement
I think we need an iov_iter or iov_iter-light there in the long run.
Same for ioctl so that we can pass properly typed kernel or user
buffers through without all these set_fs hacks.