From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755747Ab0JSR2V (ORCPT ); Tue, 19 Oct 2010 13:28:21 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:44466 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752208Ab0JSR2T (ORCPT ); Tue, 19 Oct 2010 13:28:19 -0400 Date: Tue, 19 Oct 2010 18:28:05 +0100 From: Al Viro To: Linus Torvalds Cc: Eric Paris , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, hch@infradead.org, zohar@us.ibm.com, warthog9@kernel.org, david@fromorbit.com, jmorris@namei.org, kyle@mcmartin.ca, hpa@zytor.com, akpm@linux-foundation.org, mingo@elte.hu Subject: Re: [PATCH 1/3] IMA: move read/write counters into struct inode Message-ID: <20101019172805.GU19804@ZenIV.linux.org.uk> References: <20101019011650.25346.99614.stgit@paris.rdu.redhat.com> <1287506215.2530.187.camel@localhost.localdomain> <20101019165530.GT19804@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 19, 2010 at 10:03:48AM -0700, Linus Torvalds wrote: > On Tue, Oct 19, 2010 at 9:55 AM, Al Viro wrote: > > > > a) i_writecount is about VM_DENYWRITE, basically. ?Reusing it for ima could > > get unpleasant; when it's positive, we are fine, but it can get negative as > > well. ?IMA will have interesting time dealing with that. > > > > b) i_count is simply a refcount for struct inode. ?Not exactly the number > > of dentries, but that's the main contributor. ?Basically, that's "how many > > pointers outside of inode hash chains point that that struct inode at the > > moment". > > My question was deeper. More along the lines of "why would IMA care?" > > How/why could IMA ever care about the pointless and trivial > differences between its current private open/read/write counts and the > counts that we already maintain? > > Yes, yes, I realize that they have technical differences in what they > count. That's not the question. The question is "Why would IMA care?" I'd rather not say what I think about IMA sanity (and usefulness); as for what it tries to do... They want to whine if you open a file that is already opened for write and they want to whine if you open a file for write when it's already opened for read. Unless they decide to leave the file alone, that is.