Re: [PATCH 10/15] mm: Use pagevec_lookup_range_tag() in __filemap_fdatawait_range()

[Dave Chinner <david@xxxxxxxxxxxxx>]

On Wed, Sep 27, 2017 at 06:03:29PM +0200, Jan Kara wrote:
> Use pagevec_lookup_range_tag() in __filemap_fdatawait_range() as it is
> interested only in pages from given range. Remove unnecessary code
> resulting from this.
> 
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
>  mm/filemap.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index fe20329c83cd..479fc54b7cd1 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -421,18 +421,13 @@ static void __filemap_fdatawait_range(struct address_space *mapping,
>  
>  	pagevec_init(&pvec, 0);
>  	while ((index <= end) &&
> -			(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
> -			PAGECACHE_TAG_WRITEBACK,
> -			min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
> +			(nr_pages = pagevec_lookup_range_tag(&pvec, mapping,
> +			&index, end, PAGECACHE_TAG_WRITEBACK, PAGEVEC_SIZE))) {

While touching this, can we clean this up by moving the lookup
outside the while condition? i.e:

	while (index <= end) {
		unsigned i;

		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index,
				end, PAGECACHE_TAG_WRITEBACK, PAGEVEC_SIZE);
		if (!nr_pages)
			break;

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx