From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH 11/35] undo-io: be more flexible about setting block size Date: Tue, 5 May 2015 10:21:28 -0400 Message-ID: <20150505142128.GC12468@thunk.org> References: <20150402023359.25243.79782.stgit@birch.djwong.org> <20150402023513.25243.34847.stgit@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: "Darrick J. Wong" Return-path: Received: from imap.thunk.org ([74.207.234.97]:45871 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993154AbbEEOV3 (ORCPT ); Tue, 5 May 2015 10:21:29 -0400 Content-Disposition: inline In-Reply-To: <20150402023513.25243.34847.stgit@birch.djwong.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Apr 01, 2015 at 07:35:13PM -0700, Darrick J. Wong wrote: > Most of the e2fsprogs utilities set the IO block size multiple times > (once to 1k to read the superblock, then again to set the real block > size if we find a real superblock). Unfortunately, the undo IO > manager only lets the block size be set once. For the non-mke2fs > utilities we'd rather catch the real block size and use that. mke2fs > of course wants to use a really large block size since it's probably > writing a lot of data. > > Therefore, if we haven't written any blocks to the undo file, it's > perfectly fine to allow block size changes. For mke2fs, we'll modify > the IO channel option that lets us set the huge size to lock that > in place. This greatly reduces index overhead for undo files for > e2fsck/tune2fs/resize2fs while continuing the practice of reducing > it even more for mke2fs. > > Signed-off-by: Darrick J. Wong Applied, thanks. - Ted