Re: What sort of inode state does ->evict_inode() expect to see? [was Re: 9p: fscache duplicate cookie]

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Dominique Martinet <asmadeus@codewreck.org>
Cc: Luis Henriques <lhenriques@suse.de>,
	David Howells <dhowells@redhat.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Eric Van Hensbergen <ericvh@gmail.com>,
	Latchesar Ionkov <lucho@ionkov.net>,
	linux-fsdevel@vger.kernel.org,
	v9fs-developer@lists.sourceforge.net
Subject: Re: What sort of inode state does ->evict_inode() expect to see? [was Re: 9p: fscache duplicate cookie]
Date: Mon, 17 May 2021 23:09:39 +0530	[thread overview]
Message-ID: <4a83552c-742d-e327-b810-7da43b913daf@linux.ibm.com> (raw)
In-Reply-To: <YJ7oxGY/eosPvCiA@codewreck.org>

On 5/15/21 2:46 AM, Dominique Martinet wrote:
> Hi Aneesh,
> 
> I'm going to rely on your memory here... A long, long time ago (2011!),
> you've authored this commit:
> -------
> commit ed80fcfac2565fa866d93ba14f0e75de17a8223e
> Author: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Date:   Wed Jul 6 16:32:31 2011 +0530
> 
>      fs/9p: Always ask new inode in create
>      
>      This make sure we don't end up reusing the unlinked inode object.
>      The ideal way is to use inode i_generation. But i_generation is
>      not available in userspace always.
>      
>      Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>      Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
> -------
> 
> Do you happen to remember or know *why* you wanted to make sure we don't
> reuse the unlinked inode object?
> 
>

Sorry, I don't recall all the details, hence some of these details may 
not be correct. I did look at the archives to see if we have email 
discussions around the change. I found the below related email thread.

https://lore.kernel.org/lkml/1310402460-5098-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com/

IIRC, this was to avoid picking up wrong inode from the hash? So a 
create is a new object and we want to actually avoid any comparison?
Hence pass a test function that always return false?

-aneesh