linux-kernel - Re: [PATCH] proc: introduce proc

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Message-ID: <Y72nPcDDC/+10lYK@p183>
Date:   Tue, 10 Jan 2023 20:58:21 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     Chao Yu <chao@...nel.org>
Cc:     akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] proc: introduce proc_statfs()

On Tue, Jan 10, 2023 at 11:20:03PM +0800, Chao Yu wrote:
> Introduce proc_statfs() to replace simple_statfs(), so that
> f_bsize queried from statfs() can be consistent w/ the value we
> set in s_blocksize.
> 
> stat -f /proc/
> 
> Before:
>     ID: 0        Namelen: 255     Type: proc
> Block size: 4096       Fundamental block size: 4096
> Blocks: Total: 0          Free: 0          Available: 0
> Inodes: Total: 0          Free: 0
> 
> After:
>     ID: 0        Namelen: 255     Type: proc
> Block size: 1024       Fundamental block size: 1024
> Blocks: Total: 0          Free: 0          Available: 0
> Inodes: Total: 0          Free: 0

4096 is better value is in fact.

seq_files allocate 1 page and fill it, therefore reading less than
PAGE_SIZE from /proc is mostly waste of syscalls.

I doubt anything uses f_bsize.

BTW this patch is not self contained.