Re: [PATCH v3 01/14] x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations

From: Christoph Hellwig
Date: Sun Jun 18 2017 - 04:29:09 EST

On Fri, Jun 09, 2017 at 01:23:51PM -0700, Dan Williams wrote:
> Implement a __copy_from_user_inatomic_flushcache, memcpy_page_flushcache, and
> memcpy_flushcache, that guarantee that the destination buffer is not dirty in
> the cpu cache on completion. The new copy_from_iter_flushcache and sub-routines

Wouldn't writethrough be a better name?

> will be used to replace the "pmem api" (include/linux/pmem.h +
> arch/x86/include/asm/pmem.h). The availability of copy_from_iter_flushcache()
> and memcpy_flushcache() are gated by the CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
> config symbol, and fallback to copy_from_iter_nocache() and plain memcpy()
> otherwise.

What is UACCESS about memcpy_flushcache?