linux-kernel - Re: [PATCH v2] erofs: remove useless cache strategy of DELAYEDALLOC

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Message-ID: <YYaCr9YgK1I91MXX@B-P7TQMD6M-0146.local>
Date:   Sat, 6 Nov 2021 21:27:11 +0800
From:   Gao Xiang <hsiangkao@...ux.alibaba.com>
To:     Yue Hu <huyue2@...ong.com>
Cc:     xiang@...nel.org, chao@...nel.org, linux-erofs@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, zhangwen@...ong.com,
        geshifei@...ong.com, zbestahu@...il.com
Subject: Re: [PATCH v2] erofs: remove useless cache strategy of DELAYEDALLOC

Hi Yue,

On Sat, Nov 06, 2021 at 04:23:15PM +0800, Yue Hu wrote:
> DELAYEDALLOC is not used at all, remove related dead code. Also,
> remove the blank line at the end of zdata.h.

I'll update the commit message to:

After commit 1825c8d7ce93 ("erofs: force inplace I/O under low
memory scenario") and TRYALLOC is widely used, DELAYEDALLOC won't
be used anymore. Remove related dead code. Also, remove the blank
line at the end of zdata.h.

> 
> Signed-off-by: Yue Hu <huyue2@...ong.com>

Reviewed-by: Gao Xiang <hsiangkao@...ux.alibaba.com>

Thanks,
Gao Xiang

> ---
> v2: remove the blank line at the end of zdata.h.
> 
>  fs/erofs/zdata.c | 20 --------------------
>  fs/erofs/zdata.h |  1 -
>  2 files changed, 21 deletions(-)
> 
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index bcb1b91b234f..812c7c6ae456 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -96,16 +96,9 @@ static void z_erofs_free_pcluster(struct z_erofs_pcluster *pcl)
>  	DBG_BUGON(1);
>  }
>  
> -/*
> - * a compressed_pages[] placeholder in order to avoid
> - * being filled with file pages for in-place decompression.
> - */
> -#define PAGE_UNALLOCATED     ((void *)0x5F0E4B1D)
> -
>  /* how to allocate cached pages for a pcluster */
>  enum z_erofs_cache_alloctype {
>  	DONTALLOC,	/* don't allocate any cached pages */
> -	DELAYEDALLOC,	/* delayed allocation (at the time of submitting io) */
>  	/*
>  	 * try to use cached I/O if page allocation succeeds or fallback
>  	 * to in-place I/O instead to avoid any direct reclaim.
> @@ -267,10 +260,6 @@ static void preload_compressed_pages(struct z_erofs_collector *clt,
>  			/* I/O is needed, no possible to decompress directly */
>  			standalone = false;
>  			switch (type) {
> -			case DELAYEDALLOC:
> -				t = tagptr_init(compressed_page_t,
> -						PAGE_UNALLOCATED);
> -				break;
>  			case TRYALLOC:
>  				newpage = erofs_allocpage(pagepool, gfp);
>  				if (!newpage)
> @@ -1089,15 +1078,6 @@ static struct page *pickup_page_for_submission(struct z_erofs_pcluster *pcl,
>  	if (!page)
>  		goto out_allocpage;
>  
> -	/*
> -	 * the cached page has not been allocated and
> -	 * an placeholder is out there, prepare it now.
> -	 */
> -	if (page == PAGE_UNALLOCATED) {
> -		tocache = true;
> -		goto out_allocpage;
> -	}
> -
>  	/* process the target tagged pointer */
>  	t = tagptr_init(compressed_page_t, page);
>  	justfound = tagptr_unfold_tags(t);
> diff --git a/fs/erofs/zdata.h b/fs/erofs/zdata.h
> index 879df5362777..4a69515dea75 100644
> --- a/fs/erofs/zdata.h
> +++ b/fs/erofs/zdata.h
> @@ -179,4 +179,3 @@ static inline void z_erofs_onlinepage_endio(struct page *page)
>  #define Z_EROFS_VMAP_GLOBAL_PAGES	2048
>  
>  #endif
> -
> -- 
> 2.17.1
> 
>