From: Andreas Dilger Subject: Re: [RFC] [PATCH] Flex_BG ialloc awareness V2. Date: Thu, 13 Dec 2007 15:58:57 -0700 Message-ID: <20071213225857.GK3214@webber.adilger.int> References: <20071206161045.1054bbe7@gara> <20071207101428.GE3214@webber.adilger.int> <20071207095212.037ca68a@gara> <20071211110033.GQ3214@webber.adilger.int> <20071211100812.557b923b@gara> <20071211231528.GS3214@webber.adilger.int> <20071213095112.100b3d9e@gara> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4 To: "Jose R. Santos" Return-path: Received: from mail.clusterfs.com ([74.0.229.162]:35441 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763905AbXLMW67 (ORCPT ); Thu, 13 Dec 2007 17:58:59 -0500 Content-Disposition: inline In-Reply-To: <20071213095112.100b3d9e@gara> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Dec 13, 2007 09:51 -0600, Jose R. Santos wrote: > Now, storing the bits only guaranties that the flexbg size is always a > power-of-two and does not guarantee that the super block flexbg size > represents the actual meta-data grouping on disk. For this we need to > verify that the bitmap offsets match what the super block reports. It > may be an unlikely scenario, but it may be worth it to check this as > well at mount time. I'm not sure what you mean... Isn't the flexbg size just a count of the number of block groups? If it is always a power of two, and the groups per metabg is always a power of two (it is) then they will always be even multiples. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.