Re: [PATCH] ovl: tentative fix for broken vfs_open() on stacked overlayfs.

From	Quentin Casasnovas <quentin.casasnovas@oracle.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] ovl: tentative fix for broken vfs_open() on stacked overlayfs.
Date	2016-11-28 12:10 +0100
Message-ID	<sIrYT-1kN-69@gated-at.bofh.it> (permalink)
References	<sHq8N-1SA-29@gated-at.bofh.it> <sHsaB-3mU-17@gated-at.bofh.it> <sHum6-4EJ-11@gated-at.bofh.it> <sIqJr-lL-7@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

[Multipart message — attachments visible in raw view] - view raw

On Mon, Nov 28, 2016 at 10:45:18AM +0100, Miklos Szeredi wrote:
> On Fri, Nov 25, 2016 at 08:28:47PM +0100, Quentin Casasnovas wrote:
> > On Fri, Nov 25, 2016 at 06:09:23PM +0100, Quentin Casasnovas wrote:
> > > If two overlayfs filesystems are stacked on top of each other, then we need
> > > to recurse when opening a file.  This used to work and was first broken by:
> > > 
> > >   4bacc9c9234c ("overlayfs: Make f_path always point to the overlay...")
> > > 
> > > and fixed by:
> > > 
> > >   1c8a47df36d7 ("ovl: fix open in stacked overlay")
> > > 
> > > But it looks like it was re-introduced in:
> > > 
> > >   2d902671ce1c ("vfs: merge .d_select_inode() into .d_real()")
> 
> 
> Following patch should fix it (it's there in your patch, so you weren't too far
> off).  It needs more testing and review, but I think it fixes the basic problem.
> 
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index edd46a0e951d..f4d2f63fa53a 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -328,7 +328,7 @@ static struct dentry *ovl_d_real(struct dentry *dentry,
>  	if (!real)
>  		goto bug;
>  
> -	if (!inode || inode == d_inode(real))
> +	if (inode && inode == d_inode(real))
>  		return real;
>  
>  	/* Handle recursion */

The above patch works for me, thanks!

Tested-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>

Q

Back to linux.kernel | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

opening a file on a stacked overlayfs is broken. Quentin Casasnovas <quentin.casasnovas@oracle.com> - 2016-11-25 16:00 +0100
  [PATCH] ovl: tentative fix for broken vfs_open() on stacked overlayfs. Quentin Casasnovas <quentin.casasnovas@oracle.com> - 2016-11-25 18:10 +0100
    Re: [PATCH] ovl: tentative fix for broken vfs_open() on stacked  overlayfs. Quentin Casasnovas <quentin.casasnovas@oracle.com> - 2016-11-25 20:30 +0100
      Re: [PATCH] ovl: tentative fix for broken vfs_open() on stacked  overlayfs. Miklos Szeredi <miklos@szeredi.hu> - 2016-11-28 10:50 +0100
        Re: [PATCH] ovl: tentative fix for broken vfs_open() on stacked  overlayfs. Quentin Casasnovas <quentin.casasnovas@oracle.com> - 2016-11-28 12:10 +0100

csiph-web