linux-kernel - Re: [RFC] vfs: skip extra attributes check on removal for symlinks

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Message-ID: <20180510230551.GE27853@wotan.suse.de>
Date:   Thu, 10 May 2018 23:05:51 +0000
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     Al Viro <viro@...IV.linux.org.uk>
Cc:     "Luis R. Rodriguez" <mcgrof@...nel.org>,
        linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org,
        sandeen@...deen.net, darrick.wong@...cle.com, dhowells@...hat.com,
        tytso@....edu, fliu@...e.com, jack@...e.cz, jeffm@...e.com,
        nborisov@...e.com, jake.norris@...e.com, mtk.manpages@...il.com,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC] vfs: skip extra attributes check on removal for symlinks

On Thu, May 10, 2018 at 09:48:07PM +0100, Al Viro wrote:
> On Thu, Apr 26, 2018 at 04:46:39PM -0700, Luis R. Rodriguez wrote:
> 
> > Since we cannot set these attributes we should special-case the
> > immutable/append on delete for symlinks, this would be consistent with
> > what we *do* allow on Linux for all filesystems.
> 
> Er...  So why not simply sanity-check it in places that set it on
> inodes? 

The patch is not about sanity-checks on setters though as *that* is in place
already. Its about the case where the filesystem gets corrupted and the VFS
*still* does process these attributes for symlinks and still prevents
deletion because of these attributes.

So we already do not allow for settings these attributes.

> If anything, I would suggest
> 	* converting all places that set those in ->i_flags to
> inode_set_flags()
> 	* making inode_set_flags() check and return an error on
> that...

But if I misunderstood your suggestion please let me know. I'll send out
a v2 RFC next which illustrates what filesystems can do for now.

  Luis