linux-kernel - Re: [PATCH RFC PKS/PMEM 33/58] fs/cramfs: Utilize new kmap

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Message-ID: <nycvar.YSQ.7.78.906.2010131436200.2184@knanqh.ubzr>
Date:   Tue, 13 Oct 2020 14:36:56 -0400 (EDT)
From:   Nicolas Pitre <nico@...xnic.net>
To:     Ira Weiny <ira.weiny@...el.com>
cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
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        Dave Hansen <dave.hansen@...ux.intel.com>,
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        Fenghua Yu <fenghua.yu@...el.com>, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org,
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Subject: Re: [PATCH RFC PKS/PMEM 33/58] fs/cramfs: Utilize new
 kmap_thread()

On Fri, 9 Oct 2020, ira.weiny@...el.com wrote:

> From: Ira Weiny <ira.weiny@...el.com>
> 
> The kmap() calls in this FS are localized to a single thread.  To avoid
> the over head of global PKRS updates use the new kmap_thread() call.
> 
> Cc: Nicolas Pitre <nico@...xnic.net>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>

Acked-by: Nicolas Pitre <nico@...xnic.net>

>  fs/cramfs/inode.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
> index 912308600d39..003c014a42ed 100644
> --- a/fs/cramfs/inode.c
> +++ b/fs/cramfs/inode.c
> @@ -247,8 +247,8 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
>  		struct page *page = pages[i];
>  
>  		if (page) {
> -			memcpy(data, kmap(page), PAGE_SIZE);
> -			kunmap(page);
> +			memcpy(data, kmap_thread(page), PAGE_SIZE);
> +			kunmap_thread(page);
>  			put_page(page);
>  		} else
>  			memset(data, 0, PAGE_SIZE);
> @@ -826,7 +826,7 @@ static int cramfs_readpage(struct file *file, struct page *page)
>  
>  	maxblock = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
>  	bytes_filled = 0;
> -	pgdata = kmap(page);
> +	pgdata = kmap_thread(page);
>  
>  	if (page->index < maxblock) {
>  		struct super_block *sb = inode->i_sb;
> @@ -914,13 +914,13 @@ static int cramfs_readpage(struct file *file, struct page *page)
>  
>  	memset(pgdata + bytes_filled, 0, PAGE_SIZE - bytes_filled);
>  	flush_dcache_page(page);
> -	kunmap(page);
> +	kunmap_thread(page);
>  	SetPageUptodate(page);
>  	unlock_page(page);
>  	return 0;
>  
>  err:
> -	kunmap(page);
> +	kunmap_thread(page);
>  	ClearPageUptodate(page);
>  	SetPageError(page);
>  	unlock_page(page);
> -- 
> 2.28.0.rc0.12.gb6a658bd00c9
> 
>