On 06/07/2013 08:17 AM, Kirill A. Shutemov wrote:
<snip>
> I guess this way is better, right?
>
> @@ -2382,6 +2393,7 @@ static ssize_t generic_perform_write(struct file *file,
> unsigned long bytes; /* Bytes to write to page */
> size_t copied; /* Bytes copied from user */
> void *fsdata;
> + int subpage_nr = 0;
>
> offset = (pos & (PAGE_CACHE_SIZE - 1));
> bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
> @@ -2411,8 +2423,14 @@ again:
> if (mapping_writably_mapped(mapping))
> flush_dcache_page(page);
>
> + if (PageTransHuge(page)) {
> + off_t huge_offset = pos & ~HPAGE_PMD_MASK;
> + subpage_nr = huge_offset >> PAGE_CACHE_SHIFT;
> + }
> +
> pagefault_disable();
> - copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
> + copied = iov_iter_copy_from_user_atomic(page + subpage_nr, i,
> + offset, bytes);
> pagefault_enable();
> flush_dcache_page(page);
That looks substantially easier to understand to me. Nice.
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