linux-kernel - Re: [ 02/42] TTY: do not update atime/mtime on read/write

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Message-ID: <20130502161146.GA7454@hostway.ca>
Date:	Thu, 2 May 2013 09:11:46 -0700
From:	Simon Kirby <sim@...tway.ca>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	stable <stable@...r.kernel.org>, Jiri Slaby <jslaby@...e.cz>
Subject: Re: [ 02/42] TTY: do not update atime/mtime on read/write

On Tue, Apr 30, 2013 at 06:41:44PM -0700, Linus Torvalds wrote:

> On Tue, Apr 30, 2013 at 5:57 PM, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > Patch is whitespace-damaged and totally untested! Caveat applicator.
> 
> Ok, so it's still whitespace-damaged, but it seems to work. The
> appended has the "8 second rule" too..
> 
> Comments? Simon?

Tested -- both hunks seem to work as intended. Thanks!

Simon-

Below became b0b885657b6c8ef63a46bc9299b2a7715d19acde

>            Linus
> 
> --- snip snip ---
>  drivers/tty/pty.c    | 3 +++
>  drivers/tty/tty_io.c | 4 ++--
>  2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
> index a62798fcc014..59bfaecc4e14 100644
> --- a/drivers/tty/pty.c
> +++ b/drivers/tty/pty.c
> @@ -681,6 +681,9 @@ static int ptmx_open(struct inode *inode, struct file *filp)
> 
>         nonseekable_open(inode, filp);
> 
> +       /* We refuse fsnotify events on ptmx, since it's a shared resource */
> +       filp->f_mode |= FMODE_NONOTIFY;
> +
>         retval = tty_alloc_file(filp);
>         if (retval)
>                 return retval;
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 97ebc8c5864e..6464029e4860 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -988,10 +988,10 @@ void start_tty(struct tty_struct *tty)
> 
>  EXPORT_SYMBOL(start_tty);
> 
> +/* We limit tty time update visibility to every 8 seconds or so. */
>  static void tty_update_time(struct timespec *time)
>  {
> -       unsigned long sec = get_seconds();
> -       sec -= sec % 60;
> +       unsigned long sec = get_seconds() & ~7;
>         if ((long)(sec - time->tv_sec) > 0)
>                 time->tv_sec = sec;
>  }
--
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