From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: [RFC][PATCH] nfsd regression since delayed fput() Date: Thu, 17 Oct 2013 19:39:52 +0100 Message-ID: <20131017183952.GS13318@ZenIV.linux.org.uk> References: <20131016185209.GO13318@ZenIV.linux.org.uk> <20131017181457.GA6987@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "J. Bruce Fields" , linux-fsdevel To: Linus Torvalds Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:59434 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758643Ab3JQSjz (ORCPT ); Thu, 17 Oct 2013 14:39:55 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Oct 17, 2013 at 11:29:46AM -0700, Linus Torvalds wrote: > On Thu, Oct 17, 2013 at 11:14 AM, J. Bruce Fields wrote: > > > > NFS isn't exportable and there aren't any plans to change that. > > The thing is, other filesystems have other rules. Not everybody > necessarily supports the Unix "you can remove files that are still in > use" semantics, so I could imagine EBUSY etc happening.. Yes, but... To get anything of that kind you would need to have a kernel thread open a file on such fs, do IO and fput() it, then have something attempt to unlink() it and fail with EBUSY due to fput() being delayed. If that something is *not* the same kernel thread, it's already racy - after all, if that unlink() happens while the kernel thread does IO, we are going to get what we are going to get. And if it is the same thread... What would it be? knfsd? Exporting a filesystem with possible-EBUSY-on-unlink? I don't see any exportable examples of that...