linux-kernel - Re: [PATCH] fs: Make file-nr output the total allocated file handles

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Message-ID: <20250411-gejagt-gelistet-88c56be455d1@brauner>
Date: Fri, 11 Apr 2025 16:16:08 +0200
From: Christian Brauner <brauner@...nel.org>
To: lirongqing <lirongqing@...du.com>
Cc: viro@...iv.linux.org.uk, jack@...e.cz, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs: Make file-nr output the total allocated file handles

On Thu, Apr 10, 2025 at 07:21:17PM +0800, lirongqing wrote:
> From: Li RongQing <lirongqing@...du.com>
> 
> Make file-nr output the total allocated file handles, not per-cpu
> cache number, it's more precise, and not in hot path
> 
> Signed-off-by: Li RongQing <lirongqing@...du.com>
> ---

That means grabbing a lock suddenly. Is there an actual use-case
behind this?

>  fs/file_table.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/file_table.c b/fs/file_table.c
> index c04ed94..138114d 100644
> --- a/fs/file_table.c
> +++ b/fs/file_table.c
> @@ -102,7 +102,7 @@ EXPORT_SYMBOL_GPL(get_max_files);
>  static int proc_nr_files(const struct ctl_table *table, int write, void *buffer,
>  			 size_t *lenp, loff_t *ppos)
>  {
> -	files_stat.nr_files = get_nr_files();
> +	files_stat.nr_files = percpu_counter_sum_positive(&nr_files);
>  	return proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
>  }
>  
> -- 
> 2.9.4
>