From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org ([198.137.202.9]:38294 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752139AbcHKRsE (ORCPT ); Thu, 11 Aug 2016 13:48:04 -0400 Date: Thu, 11 Aug 2016 10:48:02 -0700 From: Christoph Hellwig Subject: Re: [PATCH] common/defrag: rework _require_defrag for ext4 Message-ID: <20160811174802.GC31540@infradead.org> References: <20160804200246.GA2208@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160804200246.GA2208@localhost.localdomain> Sender: fstests-owner@vger.kernel.org To: Eric Whitney Cc: fstests@vger.kernel.org, linux-ext4@vger.kernel.org, tytso@mit.edu List-ID: On Thu, Aug 04, 2016 at 04:02:46PM -0400, Eric Whitney wrote: > The existing _require_defrag function rejects ext4 file systems > mounted with the dax option or constructed without extents. However, > there are also a number of other ext4 file system configuration cases > that do not currently support online defrag, including encryption, data > journaling, and bigalloc. In the future, online defrag functionality > may be implemented for some of these, and new configuration cases > could be added that don't support it. > > Rather than add a laundry list of mount and file system configuration > options to the existing _require_defrag function that will need ongoing > maintenance, use the available src/e4compact program to directly > determine whether the kernel supports ext4's move extent ioctl on the > test file system. This look reasonable - but I wonder if we could just come up with an even more generic version that uses your approach on all file systems, so that the only per-fs logic left would be to apply the DEFRAG_PROG variable.