From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ted Ts'o Subject: Re: [PATCH 4/4 v2] ext4: Do not discard group with BLOCK_UNINIT set Date: Tue, 6 Mar 2012 17:18:15 -0500 Message-ID: <20120306221815.GA5472@thunk.org> References: <1330690318-22627-1-git-send-email-lczerner@redhat.com> <1330690318-22627-4-git-send-email-lczerner@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Lukas Czerner Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:58695 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030811Ab2CFWSS (ORCPT ); Tue, 6 Mar 2012 17:18:18 -0500 Content-Disposition: inline In-Reply-To: <1330690318-22627-4-git-send-email-lczerner@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Mar 02, 2012 at 01:11:58PM +0100, Lukas Czerner wrote: > Because the BLOCK_UNINIT is only set on mke2fs time and cleared when > allocation from that group takes place we know that when set, there was > not anything allocated from that group, hence there should not be anything > to discard from the file system point of view. There's a really good reason to set BLOCK_UNINIT once we have noticed that all of the blocks in the block group have been released.... If you have a 3TB HDD, running e2fsck takes 4 times as long if all of the block groups have BLOCK_UNINIT cleared, compared to a freshly mkfs'ed file system. As a result of my getting really annoyed at how long it took in this case, I'm planning on making e2fsck clear BLOCK_UNINIT if possible, so that subsequent e2fsck's (and dumpe2fs and debugfs invocations) can also be fast. - Ted