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Date: Thu, 17 Sep 2009 14:59:35 +0800
Message-ID: <2375c9f90909162359m14ec7640m88ddd7ba54d6e793@mail.gmail.com>
Subject: Re: [PATCH 3/3][mmotm] updateing size of kcore
From: =?UTF-8?Q?Am=C3=A9rico_Wang?= <xiyou.wangcong@gmail.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org
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On Thu, Sep 17, 2009 at 10:45 AM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@jp.fujitsu.com> wrote:
>
> After memory hotplug (or other events in future), kcore size
> can be modified.
>
> To update inode->i_size, we have to know inode/dentry but we
> can't get it from inside /proc directly.
> But considerinyg memory hotplug, kcore image is updated only when
> it's opened. Then, updating inode->i_size at open() is enough.
>
> Cc: WANG Cong <xiyou.wangcong@gmail.com>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


This patch looks fine.

However, I am thinking if kcore is the only file under /proc whose size
is changed dynamically? If no, that probably means we need to change
generic proc code.

Thanks!

> ---
>  fs/proc/kcore.c |    5 +++++
>  1 file changed, 5 insertions(+)
>
> Index: mmotm-2.6.31-Sep14/fs/proc/kcore.c
> ===================================================================
> --- mmotm-2.6.31-Sep14.orig/fs/proc/kcore.c
> +++ mmotm-2.6.31-Sep14/fs/proc/kcore.c
> @@ -546,6 +546,11 @@ static int open_kcore(struct inode *inod
>                return -EPERM;
>        if (kcore_need_update)
>                kcore_update_ram();
> +       if (i_size_read(inode) != proc_root_kcore->size) {
> +               mutex_lock(&inode->i_mutex);
> +               i_size_write(inode, proc_root_kcore->size);
> +               mutex_unlock(&inode->i_mutex);
> +       }
>        return 0;
>  }
>
>
>