Re: [PATCH 1/2] iomap: Use kmap_local_page instead of kmap_atomic

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Aug 03, 2021 at 08:31:33PM +0100, Matthew Wilcox (Oracle) wrote:
> kmap_atomic() has the side-effect of disabling pagefaults and
> preemption.  kmap_local_page() does not do this and is preferred.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Pretty straightforward.
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/iomap/buffered-io.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index c1c8cd41ea81..8ee0211bea86 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -223,10 +223,10 @@ static int iomap_read_inline_data(struct inode *inode, struct page *page,
>  	if (poff > 0)
>  		iomap_page_create(inode, page);
>  
> -	addr = kmap_atomic(page) + poff;
> +	addr = kmap_local_page(page) + poff;
>  	memcpy(addr, iomap->inline_data, size);
>  	memset(addr + size, 0, PAGE_SIZE - poff - size);
> -	kunmap_atomic(addr);
> +	kunmap_local(addr);
>  	iomap_set_range_uptodate(page, poff, PAGE_SIZE - poff);
>  	return PAGE_SIZE - poff;
>  }
> @@ -682,9 +682,9 @@ static size_t iomap_write_end_inline(struct inode *inode, struct page *page,
>  	BUG_ON(!iomap_inline_data_valid(iomap));
>  
>  	flush_dcache_page(page);
> -	addr = kmap_atomic(page);
> -	memcpy(iomap_inline_data(iomap, pos), addr + pos, copied);
> -	kunmap_atomic(addr);
> +	addr = kmap_local_page(page) + pos;
> +	memcpy(iomap_inline_data(iomap, pos), addr, copied);
> +	kunmap_local(addr);
>  
>  	mark_inode_dirty(inode);
>  	return copied;
> -- 
> 2.30.2
>