From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 13/28] VFS: Introduce soft reference counts Date: Mon, 25 Oct 2004 16:25:21 +0100 Sender: linux-fsdevel-owner@vger.kernel.org Message-ID: <20041025152521.GA1959@infradead.org> References: <10987154731896@sun.com> <10987155032816@sun.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, raven@themaw.net Return-path: Received: from phoenix.infradead.org ([81.187.226.98]:61452 "EHLO phoenix.infradead.org") by vger.kernel.org with ESMTP id S261954AbUJYPZW (ORCPT ); Mon, 25 Oct 2004 11:25:22 -0400 To: Mike Waychison Content-Disposition: inline In-Reply-To: <10987155032816@sun.com> List-Id: linux-fsdevel.vger.kernel.org On Mon, Oct 25, 2004 at 10:45:03AM -0400, Mike Waychison wrote: > This patch introduces the concept of a 'soft' reference count for a vfsmount. > This type of reference count allows for references to be held on mountpoints > that do not affect their busy states for userland unmounting. Some might > argue that this is wrong because 'when I unmount a filesystem, I want the > resources associated with it to go away too', but this way of thinking was > deprecated with the addition of namespaces and --bind back in the 2.4 series. > > A future addition may see a callback mechanism so that in kernel users can > use a given mountpoint and have it deregistered some way (quota and > accounting come to mind). > > These soft reference counts are used by a later patch that adds an interface > for holding and manipulating mountpoints using filedescriptors. You haven't explained why you actually need it, though.