Re: [PATCH 4/6] staging: erofs: cleanup `z_erofs_vle_normalaccess_readpages'

[Chao Yu]

Hi Xiang,

On 2018/9/19 13:49, Gao Xiang wrote:
> This patch introduces `__should_decompress_synchronously' to
> cleanup `z_erofs_vle_normalaccess_readpages'.
> 
> Signed-off-by: Gao Xiang <gaoxiang25@xxxxxxxxxx>
> ---
>  drivers/staging/erofs/internal.h  | 11 +++++++++++
>  drivers/staging/erofs/super.c     |  5 +++++
>  drivers/staging/erofs/unzip_vle.c | 20 ++++++--------------
>  3 files changed, 22 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/staging/erofs/internal.h b/drivers/staging/erofs/internal.h
> index cfcc6db..c84eb97 100644
> --- a/drivers/staging/erofs/internal.h
> +++ b/drivers/staging/erofs/internal.h
> @@ -95,6 +95,9 @@ struct erofs_sb_info {
>  	/* the dedicated workstation for compression */
>  	struct radix_tree_root workstn_tree;
>  
> +	/* threshold for decompression synchronously */
> +	unsigned int max_sync_decompress_pages;
> +
>  #ifdef EROFS_FS_HAS_MANAGED_CACHE
>  	struct inode *managed_cache;
>  #endif
> @@ -273,6 +276,14 @@ extern int erofs_try_to_free_cached_page(struct address_space *mapping,
>  	struct page *page);
>  #endif
>  
> +#define DEFAULT_MAX_SYNC_DECOMPRESS_PAGES	4
> +
> +static inline bool __should_decompress_synchronously(struct erofs_sb_info *sbi,
> +						     unsigned int nr)
> +{
> +	return nr <= sbi->max_sync_decompress_pages;

-		nr_pages < 4 /* sync */);

There is a little bit changed except cleanup, IIUC, would it be any difference
of performance around boundary of four pages?

Thanks,

> +}
> +
>  #endif
>  
>  /* we strictly follow PAGE_SIZE and no buffer head yet */
> diff --git a/drivers/staging/erofs/super.c b/drivers/staging/erofs/super.c
> index 802202c..5b87f59 100644
> --- a/drivers/staging/erofs/super.c
> +++ b/drivers/staging/erofs/super.c
> @@ -162,6 +162,11 @@ static void erofs_build_fault_attr(struct erofs_sb_info *sbi,
>  
>  static void default_options(struct erofs_sb_info *sbi)
>  {
> +	/* set up some FS parameters */
> +#ifdef CONFIG_EROFS_FS_ZIP
> +	sbi->max_sync_decompress_pages = DEFAULT_MAX_SYNC_DECOMPRESS_PAGES;
> +#endif
> +
>  #ifdef CONFIG_EROFS_FS_XATTR
>  	set_opt(sbi, XATTR_USER);
>  #endif
> diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c
> index 9fe18cd3..337a82d 100644
> --- a/drivers/staging/erofs/unzip_vle.c
> +++ b/drivers/staging/erofs/unzip_vle.c
> @@ -1308,12 +1308,14 @@ static int z_erofs_vle_normalaccess_readpage(struct file *file,
>  	return 0;
>  }
>  
> -static inline int __z_erofs_vle_normalaccess_readpages(
> -	struct file *filp,
> -	struct address_space *mapping,
> -	struct list_head *pages, unsigned int nr_pages, bool sync)
> +static int z_erofs_vle_normalaccess_readpages(struct file *filp,
> +					      struct address_space *mapping,
> +					      struct list_head *pages,
> +					      unsigned int nr_pages)
>  {
>  	struct inode *const inode = mapping->host;
> +	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
> +	const bool sync = __should_decompress_synchronously(sbi, nr_pages);
>  
>  	struct z_erofs_vle_frontend f = VLE_FRONTEND_INIT(inode);
>  	gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
> @@ -1372,16 +1374,6 @@ static inline int __z_erofs_vle_normalaccess_readpages(
>  	return 0;
>  }
>  
> -static int z_erofs_vle_normalaccess_readpages(
> -	struct file *filp,
> -	struct address_space *mapping,
> -	struct list_head *pages, unsigned int nr_pages)
> -{
> -	return __z_erofs_vle_normalaccess_readpages(filp,
> -		mapping, pages, nr_pages,
> -		nr_pages < 4 /* sync */);
> -}
> -
>  const struct address_space_operations z_erofs_vle_normalaccess_aops = {
>  	.readpage = z_erofs_vle_normalaccess_readpage,
>  	.readpages = z_erofs_vle_normalaccess_readpages,
>