Re: [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable

From: Al Viro
Date: Fri Aug 27 2021 - 14:54:45 EST


On Fri, Aug 27, 2021 at 06:49:12PM +0200, Andreas Gruenbacher wrote:
> Introduce a new fault_in_iov_iter_writeable helper for safely faulting
> in an iterator for writing. Uses get_user_pages() to fault in the pages
> without actually writing to them, which would be destructive.
>
> We'll use fault_in_iov_iter_writeable in gfs2 once we've determined that
> the iterator passed to .read_iter isn't in memory.

Again, the calling conventions are wrong. Make it success/failure or
0/-EFAULT. And it's inconsistent for iovec and non-iovec cases as it is.