From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com ([192.55.52.93]:7700 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761424AbdKQUsC (ORCPT ); Fri, 17 Nov 2017 15:48:02 -0500 Date: Fri, 17 Nov 2017 13:48:01 -0700 From: Ross Zwisler Subject: Re: [xfsprogs PATCH 2/2] xfs_io: add a new 'log_writes' command Message-ID: <20171117204801.GA16597@linux.intel.com> References: <20171117202524.24696-1-ross.zwisler@linux.intel.com> <20171117202524.24696-3-ross.zwisler@linux.intel.com> <84006b9c-90db-7eea-0bdc-b73da1bb1394@sandeen.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <84006b9c-90db-7eea-0bdc-b73da1bb1394@sandeen.net> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Eric Sandeen Cc: Ross Zwisler , linux-xfs , linux-nvdimm , fstests , Jan Kara , Dave Chinner , Dan Williams On Fri, Nov 17, 2017 at 02:39:07PM -0600, Eric Sandeen wrote: > On 11/17/17 2:25 PM, Ross Zwisler wrote: > > Add a new 'log_writes' command to xfs_io so that we can add dm-log-writes > > log marks via the external 'dmsetup' executable. It's helpful to allow > > users of xfs_io to adds these marks from within xfs_io instead of waiting > > until after xfs_io exits because then they are able to replay the > > dm-log-writes log up to immediately after another xfs_io operation such as > > mwrite. This isolates the log replay from other operations that happen as > > part of xfs_io exiting (file handles being closed, mmaps being torn down, > > etc.). This also allows users to insert multiple marks between different > > xfs_io commands. > > > > Signed-off-by: Ross Zwisler > > Suggested-by: Dave Chinner > > Without reviewing in detail, what is the advantage of wrapping dmsetup > into xfs_io? My first inclination is that there is none at all, and > xfstests can call dmsetup as easily as they can call xfs_io. No? > > -Eric I commented on this a bit in the changelog for the 2nd patch: It's helpful to allow users of xfs_io to adds these marks from within xfs_io instead of waiting until after xfs_io exits because then they are able to replay the dm-log-writes log up to immediately after another xfs_io operation such as mwrite. This isolates the log replay from other operations that happen as part of xfs_io exiting (file handles being closed, mmaps being torn down, etc.). This also allows users to insert multiple marks between different xfs_io commands. I agree that the shell-out to dmsetup isn't awesome... For the current test I have written I think we can get away with just assuming that the xfs_io exit stuff won't interact too heavily with the dm-log-writes log, and we could potentially move the dmsetup call back into the fstest. This is how I initially had it, and moved it into the C program via shell-out in response to Amir's feedback: https://lists.01.org/pipermail/linux-nvdimm/2017-October/012976.html