linux-kernel - Re: [PATCH v2 5/8] xen/tmem: Use page_to_gfn rather than pfn_to

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Date:	Wed, 5 Aug 2015 11:01:32 +0100
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Julien Grall <julien.grall@...rix.com>
CC:	<xen-devel@...ts.xenproject.org>, <ian.campbell@...rix.com>,
	<stefano.stabellini@...citrix.com>, <linux-kernel@...r.kernel.org>,
	"Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	David Vrabel <david.vrabel@...rix.com>
Subject: Re: [PATCH v2 5/8] xen/tmem: Use page_to_gfn rather than
 pfn_to_gfn

On Tue, 4 Aug 2015, Julien Grall wrote:
> All the caller of xen_tmem_{get,put}_page have a struct page * in hand
> and call pfn_to_gfn for the only benefits of these 2 functions.
> 
> Rather than passing the pfn in parameter, pass directly the page and use
> directly page_to_gfn.
> 
> Signed-off-by: Julien Grall <julien.grall@...rix.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: David Vrabel <david.vrabel@...rix.com>

Reviewed-by: Stefano Stabellini <stefano.stabellini@...citrix.com>


>  drivers/xen/tmem.c | 21 +++++++--------------
>  1 file changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/xen/tmem.c b/drivers/xen/tmem.c
> index 28c97ff..e0c8dc7 100644
> --- a/drivers/xen/tmem.c
> +++ b/drivers/xen/tmem.c
> @@ -129,21 +129,17 @@ static int xen_tmem_new_pool(struct tmem_pool_uuid uuid,
>  /* xen generic tmem ops */
>  
>  static int xen_tmem_put_page(u32 pool_id, struct tmem_oid oid,
> -			     u32 index, unsigned long pfn)
> +			     u32 index, struct page *page)
>  {
> -	unsigned long gmfn = pfn_to_gfn(pfn);
> -
>  	return xen_tmem_op(TMEM_PUT_PAGE, pool_id, oid, index,
> -		gmfn, 0, 0, 0);
> +			   page_to_gfn(page), 0, 0, 0);
>  }
>  
>  static int xen_tmem_get_page(u32 pool_id, struct tmem_oid oid,
> -			     u32 index, unsigned long pfn)
> +			     u32 index, struct page *page)
>  {
> -	unsigned long gmfn = pfn_to_gfn(pfn);
> -
>  	return xen_tmem_op(TMEM_GET_PAGE, pool_id, oid, index,
> -		gmfn, 0, 0, 0);
> +			   page_to_gfn(page), 0, 0, 0);
>  }
>  
>  static int xen_tmem_flush_page(u32 pool_id, struct tmem_oid oid, u32 index)
> @@ -173,14 +169,13 @@ static void tmem_cleancache_put_page(int pool, struct cleancache_filekey key,
>  {
>  	u32 ind = (u32) index;
>  	struct tmem_oid oid = *(struct tmem_oid *)&key;
> -	unsigned long pfn = page_to_pfn(page);
>  
>  	if (pool < 0)
>  		return;
>  	if (ind != index)
>  		return;
>  	mb(); /* ensure page is quiescent; tmem may address it with an alias */
> -	(void)xen_tmem_put_page((u32)pool, oid, ind, pfn);
> +	(void)xen_tmem_put_page((u32)pool, oid, ind, page);
>  }
>  
>  static int tmem_cleancache_get_page(int pool, struct cleancache_filekey key,
> @@ -287,7 +282,6 @@ static int tmem_frontswap_store(unsigned type, pgoff_t offset,
>  {
>  	u64 ind64 = (u64)offset;
>  	u32 ind = (u32)offset;
> -	unsigned long pfn = page_to_pfn(page);
>  	int pool = tmem_frontswap_poolid;
>  	int ret;
>  
> @@ -296,7 +290,7 @@ static int tmem_frontswap_store(unsigned type, pgoff_t offset,
>  	if (ind64 != ind)
>  		return -1;
>  	mb(); /* ensure page is quiescent; tmem may address it with an alias */
> -	ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), pfn);
> +	ret = xen_tmem_put_page(pool, oswiz(type, ind), iswiz(ind), page);
>  	/* translate Xen tmem return values to linux semantics */
>  	if (ret == 1)
>  		return 0;
> @@ -313,7 +307,6 @@ static int tmem_frontswap_load(unsigned type, pgoff_t offset,
>  {
>  	u64 ind64 = (u64)offset;
>  	u32 ind = (u32)offset;
> -	unsigned long pfn = page_to_pfn(page);
>  	int pool = tmem_frontswap_poolid;
>  	int ret;
>  
> @@ -321,7 +314,7 @@ static int tmem_frontswap_load(unsigned type, pgoff_t offset,
>  		return -1;
>  	if (ind64 != ind)
>  		return -1;
> -	ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), pfn);
> +	ret = xen_tmem_get_page(pool, oswiz(type, ind), iswiz(ind), page);
>  	/* translate Xen tmem return values to linux semantics */
>  	if (ret == 1)
>  		return 0;
> -- 
> 2.1.4
> 
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