linux-kernel - Re: [PATCH] ovl: tentative fix for broken vfs

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Message-ID: <20161125192847.GH6842@chrystal.oracle.com>
Date:   Fri, 25 Nov 2016 20:28:47 +0100
From:   Quentin Casasnovas <quentin.casasnovas@...cle.com>
To:     Quentin Casasnovas <quentin.casasnovas@...cle.com>
Cc:     Miklos Szeredi <miklos@...redi.hu>, linux-kernel@...r.kernel.org,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] ovl: tentative fix for broken vfs_open() on stacked
 overlayfs.

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()")
> 
> I know close to nothing about VFS/overlayfs

And indeed I've proven it here - this tentative patch doesn't work for the
general case, it just fixes the simple test case embedded in the commit
description.

Any help appreciated!
Q

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