Re: [PATCH 07/34] mm: return an unsigned int from __do_page_cache_readahead

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, May 23, 2018 at 04:43:30PM +0200, Christoph Hellwig wrote:
> We never return an error, so switch to returning an unsigned int.  Most
> callers already did implicit casts to an unsigned type, and the one that
> didn't can be simplified now.
> 
> Suggested-by: Matthew Wilcox <willy@infradead.org>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks ok; anyone from the mm side has a strong opinion?
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  mm/internal.h  |  2 +-
>  mm/readahead.c | 15 +++++----------
>  2 files changed, 6 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/internal.h b/mm/internal.h
> index 62d8c34e63d5..954003ac766a 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -53,7 +53,7 @@ void unmap_page_range(struct mmu_gather *tlb,
>  			     unsigned long addr, unsigned long end,
>  			     struct zap_details *details);
>  
> -extern int __do_page_cache_readahead(struct address_space *mapping,
> +extern unsigned int __do_page_cache_readahead(struct address_space *mapping,
>  		struct file *filp, pgoff_t offset, unsigned long nr_to_read,
>  		unsigned long lookahead_size);
>  
> diff --git a/mm/readahead.c b/mm/readahead.c
> index 16d0cb1e2616..fa4d4b767130 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -147,16 +147,16 @@ static int read_pages(struct address_space *mapping, struct file *filp,
>   *
>   * Returns the number of pages requested, or the maximum amount of I/O allowed.
>   */
> -int __do_page_cache_readahead(struct address_space *mapping, struct file *filp,
> -			pgoff_t offset, unsigned long nr_to_read,
> -			unsigned long lookahead_size)
> +unsigned int __do_page_cache_readahead(struct address_space *mapping,
> +		struct file *filp, pgoff_t offset, unsigned long nr_to_read,
> +		unsigned long lookahead_size)
>  {
>  	struct inode *inode = mapping->host;
>  	struct page *page;
>  	unsigned long end_index;	/* The last page we want to read */
>  	LIST_HEAD(page_pool);
>  	int page_idx;
> -	int nr_pages = 0;
> +	unsigned int nr_pages = 0;
>  	loff_t isize = i_size_read(inode);
>  	gfp_t gfp_mask = readahead_gfp_mask(mapping);
>  
> @@ -223,16 +223,11 @@ int force_page_cache_readahead(struct address_space *mapping, struct file *filp,
>  	max_pages = max_t(unsigned long, bdi->io_pages, ra->ra_pages);
>  	nr_to_read = min(nr_to_read, max_pages);
>  	while (nr_to_read) {
> -		int err;
> -
>  		unsigned long this_chunk = (2 * 1024 * 1024) / PAGE_SIZE;
>  
>  		if (this_chunk > nr_to_read)
>  			this_chunk = nr_to_read;
> -		err = __do_page_cache_readahead(mapping, filp,
> -						offset, this_chunk, 0);
> -		if (err < 0)
> -			return err;
> +		__do_page_cache_readahead(mapping, filp, offset, this_chunk, 0);
>  
>  		offset += this_chunk;
>  		nr_to_read -= this_chunk;
> -- 
> 2.17.0
> 
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