linux-kernel - Re: [PATCH 05/16] overlayfs: Replace smp_read_barrier_depends() with lockless

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Message-ID: <CAJfpegtL9=YjB34kqYgGV7FRnR75uPP6LjnHBmaABK-ixZKsrw@mail.gmail.com>
Date:	Mon, 17 Nov 2014 11:35:26 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	Pranith Kumar <bobby.prani@...il.com>
Cc:	"open list:OVERLAYFS FILESYSTEM" <linux-fsdevel@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>,
	Paul McKenney <paulmck@...ux.vnet.ibm.com>
Subject: Re: [PATCH 05/16] overlayfs: Replace smp_read_barrier_depends() with lockless_dereference()

On Thu, Nov 13, 2014 at 8:24 PM, Pranith Kumar <bobby.prani@...il.com> wrote:
> Recently lockless_dereference() was added which can be used in place of
> hard-coding smp_read_barrier_depends(). The following PATCH makes the change.
>
> Signed-off-by: Pranith Kumar <bobby.prani@...il.com>
> ---
>  fs/overlayfs/super.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 08b704c..b0f050e 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -84,12 +84,10 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
>
>  static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
>  {
> -       struct dentry *upperdentry = ACCESS_ONCE(oe->__upperdentry);
>         /*
>          * Make sure to order reads to upperdentry wrt ovl_dentry_update()
>          */
> -       smp_read_barrier_depends();
> -       return upperdentry;
> +       return lockless_dereference(oe->__upperdentry);
>  }
>
>  void ovl_path_upper(struct dentry *dentry, struct path *path)
> --
> 1.9.1
>

Thanks, already in overlayfs-next branch of

  git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs-next

Thanks,
Miklos
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