Re: [RFC PATCH 2/8] brd: use memcpy_from_page() in copy_from_brd()

Ira Weiny
2021-02-08T04:36:48Z

On Sun, Feb 07, 2021 at 11:04:19AM -0800, Chaitanya Kulkarni wrote:
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> ---
> drivers/block/brd.c | 9 +++------
> 1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/block/brd.c b/drivers/block/brd.c
> index d41b7d489e9f..c1f6d768a1b3 100644
> --- a/drivers/block/brd.c
> +++ b/drivers/block/brd.c
> @@ -220,7 +220,6 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
> sector_t sector, size_t n)
> {
> struct page *page;
> - void *src;
> unsigned int offset = (sector & (PAGE_SECTORS-1)) << SECTOR_SHIFT;
> size_t copy;
>
> @@ -236,11 +235,9 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
> sector += copy >> SECTOR_SHIFT;
> copy = n - copy;
> page = brd_lookup_page(brd, sector);
> - if (page) {
> - src = kmap_atomic(page);
> - memcpy(dst, src, copy);
> - kunmap_atomic(src);
> - } else
> + if (page)
> + memcpy_from_page(dst, page, offset, copy);

Why 'offset'?

Ira

> + else
> memset(dst, 0, copy);
> }
> }
> --
> 2.22.1
>