linux-kernel - Re: [PATCH - resend] devtmpfs regression fix: reconfigure on each mount

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Date:   Mon, 17 Jan 2022 09:03:58 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     NeilBrown <neilb@...e.de>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        torvalds@...ux-foundation.org,
        Christian Brauner <christian.brauner@...ntu.com>,
        Anthony Iliopoulos <ailiop@...e.com>,
        David Howells <dhowells@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH - resend] devtmpfs regression fix: reconfigure on each
 mount

On Mon, Jan 17, 2022 at 09:07:26AM +1100, NeilBrown wrote:
> 
> Prior to Linux v5.4 devtmpfs used mount_single() which treats the given
> mount options as "remount" options, so it updates the configuration of the
> single super_block on each mount.
> Since that was changed, the mount options used for devtmpfs are ignored.
> This is a regression which affect systemd - which mounts devtmpfs
> with "-o mode=755,size=4m,nr_inodes=1m".
> 
> This patch restores the "remount" effect by calling reconfigure_single()
> 
> Fixes: d401727ea0d7 ("devtmpfs: don't mix {ramfs,shmem}_fill_super() with mount_single()")
> Acked-by: Christian Brauner <christian.brauner@...ntu.com>
> Signed-off-by: NeilBrown <neilb@...e.de>
> ---
>  drivers/base/devtmpfs.c    | 7 +++++++
>  fs/super.c                 | 4 ++--
>  include/linux/fs_context.h | 2 ++
>  3 files changed, 11 insertions(+), 2 deletions(-)

Sorry, I thought Al was going to take this as the regression came from
his tree, I should have picked it up earlier.  I'll queue it up after
5.17-rc1 is out.

thanks,

greg k-h