Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751832AbXBVUPO (ORCPT ); Thu, 22 Feb 2007 15:15:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751828AbXBVUPO (ORCPT ); Thu, 22 Feb 2007 15:15:14 -0500 Received: from mx1.redhat.com ([66.187.233.31]:54189 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751808AbXBVUPM (ORCPT ); Thu, 22 Feb 2007 15:15:12 -0500 Message-ID: <45DDF9C1.4090003@redhat.com> Date: Thu, 22 Feb 2007 15:14:57 -0500 From: Peter Staubach User-Agent: Thunderbird 1.5.0.9 (X11/20061215) MIME-Version: 1.0 To: Miklos Szeredi CC: akpm@linux-foundation.org, hugh@veritas.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] update ctime and mtime for mmaped write References: <20070221202615.a0a167f4.akpm@linux-foundation.org> <45DDD55F.4060106@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1672 Lines: 47 Miklos Szeredi wrote: >>>> Why is the flag checked in __fput()? >>>> >>>> >>> It's because of this bit in the standard: >>> >>> If there is no such call and if the underlying file is modified >>> as a result of a write reference, then these fields shall be >>> marked for update at some time after the write reference. >>> >>> It could be done in munmap/mremap, but it seemed more difficult to >>> track down all the places where the vma is removed. But yes, that may >>> be a nicer solution. >>> >> It seems to me that, with this support, a file, which is mmap'd, >> modified, but never msync'd or munmap'd, will never get its mtime >> updated. Or did I miss that? >> >> I also don't see how an mmap'd block device will get its mtime >> updated either. >> > > __fput() will be called when there are no more references to 'file', > then it will update the time if the flag is set. This applies to > regular files as well as devices. > > I suspect that you will find that, for a block device, the wrong inode gets updated. That's where the bd_inode_update_time() portion of my proposed patch came from. > But I've moved the check from __fput to remove_vma() in the next > revision of the patch, which would give slightly nicer semantics, and > be equally conforming. This still does not address the situation where a file is 'permanently' mmap'd, does it? Thanx... ps - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/