From mboxrd@z Thu Jan 1 00:00:00 1970 From: jim owens Subject: Re: [PATCH 0/4] Fiemap, an extent mapping ioctl - round 2 Date: Mon, 07 Jul 2008 20:06:12 -0400 Message-ID: <4872AF74.7070406@hp.com> References: <20080625221835.GQ28100@wotan.suse.de> <486CE430.9010902@hp.com> <20080704090057.GQ6239@webber.adilger.int> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org To: Andreas Dilger Return-path: Received: from g4t0015.houston.hp.com ([15.201.24.18]:12593 "EHLO g4t0015.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754706AbYGHAGS (ORCPT ); Mon, 7 Jul 2008 20:06:18 -0400 In-Reply-To: <20080704090057.GQ6239@webber.adilger.int> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Andreas Dilger wrote: > That doesn't make sense either. "NOT_ALIGNED" just means that it > isn't a full filesystem block, but it isn't necessarily "encoded" > in any way. I fully agree (don't let anyone know I said that) the word encoded is bad, but I was trying to produce a set of top level flags that minimize the checks applications need. >>With FIEMAP_EXTENT_ENCODED being the top flag set for >>FIEMAP_EXTENT_NET, FIEMAP_EXTENT_DATA_COMPRESSED, >>FIEMAP_EXTENT_DATA_ENCRYPTED, FIEMAP_EXTENT_DATA_INLINE, >>and FIEMAP_EXTENT_DATA_TAIL. Then FIEMAP_EXTENT_NO_BYPASS >>may or may not also be set and would say "can I get to >>the physical data", and separately "do I need to do >>special processing on it" would be FIEMAP_EXTENT_ENCODED. > > It seems to me that "ENCODED" has no relation to "NET" or "DATA_TAIL" > or "DATA_INLINE". The point is that a simple app that only processes blocks would not handle any of the above extents. When I proposed this I was thinking about layered flag checking, but now I'm starting to wonder if having top catagories actually helps applications now or for the future. It seems they still need to check "are there any flags set that I don't know", rather than checking groupings. So now I don't see FIEMAP_EXTENT_NOT_ALIGNED or "ENCODED" has any value. jim