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Re: [PATCH RFC PKS/PMEM 33/58] fs/cramfs: Utilize new kmap_thread()

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

> 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 
        char *from = kmap_atomic(page);
        memcpy(to, from + offset, len);

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);

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

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...



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