linux-kernel - Re: [PATCH] init/do_mounts.c: replace sys_mount() to do

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Message-Id: <201008171515.26175.arnd@arndb.de>
Date:	Tue, 17 Aug 2010 15:15:26 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Namhyung Kim <namhyung@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] init/do_mounts.c: replace sys_mount() to do_mount()

On Tuesday 17 August 2010, Namhyung Kim wrote:
>  static int __init do_mount_root(char *name, char *fs, int flags, void *data)
>  {
> -       int err = sys_mount(name, "/root", fs, flags, data);
> +       int err;
> +       unsigned long data_page = 0;
> +
> +       if (data) {
> +               /* data should be in a page */
> +               data_page = __get_free_page(GFP_KERNEL);
> +               if (!data_page)
> +                       return -ENOMEM;
> +               strlcpy((char *) data_page, data, PAGE_SIZE);
> +       }
> +
> +       err = do_mount(name, "/root", fs, flags, (void *) data_page);
> +
> +       if (data_page)
> +               free_page(data_page);

AFAICT there is no need for the copy at all here. The reason that sys_mount
copies to a separate page is that it gets passed an arbitrary-length user
input.

	Arnd
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