On Tue, Oct 13, 2020 at 09:01:49PM +0100, Al Viro wrote:

On Tue, Oct 13, 2020 at 08:36:43PM +0100, Matthew Wilcox wrote:

quoted

static inline void copy_to_highpage(struct page *to, void *vfrom, unsigned int size)
{
	char *vto = kmap_atomic(to);

	memcpy(vto, vfrom, size);
	kunmap_atomic(vto);
}

in linux/highmem.h ?

You mean, like
static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
{
        char *from = kmap_atomic(page);
        memcpy(to, from + offset, len);
        kunmap_atomic(from);
}

static void memcpy_to_page(struct page *page, size_t offset, const char *from, size_t len)
{
        char *to = kmap_atomic(page);
        memcpy(to + offset, from, len);
        kunmap_atomic(to);
}

static void memzero_page(struct page *page, size_t offset, size_t len)
{
        char *addr = kmap_atomic(page);
        memset(addr + offset, 0, len);
        kunmap_atomic(addr);
}

in lib/iov_iter.c?  FWIW, I don't like that "highpage" in the name and
highmem.h as location - these make perfect sense regardless of highmem;
they are normal memory operations with page + offset used instead of
a pointer...

I was thinking along those lines as well especially because of the direction
this patch set takes kmap().

Thanks for pointing these out to me.  How about I lift them to a common header?
But if not highmem.h where?

Ira