linux-kernel - Re: [PATCH v2] mm: Extend 'usage' parameter so that cluster_swap_free

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Message-ID: <5dcfd3e6-ce76-4243-8a37-ad83f8335eda@arm.com>
Date: Tue, 9 Jul 2024 09:06:07 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Barry Song <21cnbao@...il.com>, akpm@...ux-foundation.org,
 linux-mm@...ck.org
Cc: chrisl@...nel.org, david@...hat.com, hanchuanhua@...o.com,
 kasong@...cent.com, linux-kernel@...r.kernel.org, v-songbaohua@...o.com,
 ying.huang@...el.com
Subject: Re: [PATCH v2] mm: Extend 'usage' parameter so that
 cluster_swap_free_nr() can be reused

On 09/07/2024 02:21, Barry Song wrote:
> From: Barry Song <v-songbaohua@...o.com>
> 
> Extend a usage parameter so that cluster_swap_free_nr() can be reused by
> both swapcache_clear() and swap_free().
> __swap_entry_free() is quite similar but more tricky as it requires the
> return value of __swap_entry_free_locked() which cluster_swap_free_nr()
> doesn't support.
> 
> Cc: "Huang, Ying" <ying.huang@...el.com>
> Cc: Chris Li <chrisl@...nel.org>
> Cc: Ryan Roberts <ryan.roberts@....com>
> Cc: Kairui Song <kasong@...cent.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Chuanhua Han <hanchuanhua@...o.com>
> Signed-off-by: Barry Song <v-songbaohua@...o.com>

LGTM!

Reviewed-by: Ryan Roberts <ryan.roberts@....com>

> ---
>  mm/swapfile.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index f7224bc1320c..c097c513db02 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -1352,7 +1352,8 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry)
>  }
>  
>  static void cluster_swap_free_nr(struct swap_info_struct *sis,
> -		unsigned long offset, int nr_pages)
> +		unsigned long offset, int nr_pages,
> +		unsigned char usage)
>  {
>  	struct swap_cluster_info *ci;
>  	DECLARE_BITMAP(to_free, BITS_PER_LONG) = { 0 };
> @@ -1362,7 +1363,7 @@ static void cluster_swap_free_nr(struct swap_info_struct *sis,
>  	while (nr_pages) {
>  		nr = min(BITS_PER_LONG, nr_pages);
>  		for (i = 0; i < nr; i++) {
> -			if (!__swap_entry_free_locked(sis, offset + i, 1))
> +			if (!__swap_entry_free_locked(sis, offset + i, usage))
>  				bitmap_set(to_free, i, 1);
>  		}
>  		if (!bitmap_empty(to_free, BITS_PER_LONG)) {
> @@ -1396,7 +1397,7 @@ void swap_free_nr(swp_entry_t entry, int nr_pages)
>  
>  	while (nr_pages) {
>  		nr = min_t(int, nr_pages, SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER);
> -		cluster_swap_free_nr(sis, offset, nr);
> +		cluster_swap_free_nr(sis, offset, nr, 1);
>  		offset += nr;
>  		nr_pages -= nr;
>  	}
> @@ -3492,15 +3493,9 @@ int swapcache_prepare(swp_entry_t entry)
>  
>  void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry)
>  {
> -	struct swap_cluster_info *ci;
>  	unsigned long offset = swp_offset(entry);
> -	unsigned char usage;
>  
> -	ci = lock_cluster_or_swap_info(si, offset);
> -	usage = __swap_entry_free_locked(si, offset, SWAP_HAS_CACHE);
> -	unlock_cluster_or_swap_info(si, ci);
> -	if (!usage)
> -		free_swap_slot(entry);
> +	cluster_swap_free_nr(si, offset, 1, SWAP_HAS_CACHE);
>  }
>  
>  struct swap_info_struct *swp_swap_info(swp_entry_t entry)