From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: [PATCH 2/6] f2fs: support goingdown for fs shutdown Date: Fri, 9 Jan 2015 07:54:16 +1100 Message-ID: <20150108205416.GE25000@dastard> References: <1420740661-72288-1-git-send-email-jaegeuk@kernel.org> <1420740661-72288-2-git-send-email-jaegeuk@kernel.org> <54AEE06C.90806@sandeen.net> <20150108201843.GA74570@jaegeuk-mac02> <54AEE98D.5010103@sandeen.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <54AEE98D.5010103@sandeen.net> Sender: linux-kernel-owner@vger.kernel.org To: Eric Sandeen Cc: Jaegeuk Kim , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net List-Id: linux-f2fs-devel.lists.sourceforge.net On Thu, Jan 08, 2015 at 02:33:17PM -0600, Eric Sandeen wrote: > On 1/8/15 2:18 PM, Jaegeuk Kim wrote: > > On Thu, Jan 08, 2015 at 01:54:20PM -0600, Eric Sandeen wrote: > >> On 1/8/15 12:10 PM, Jaegeuk Kim wrote: > >>> This patch add an ioctl to shutdown f2fs, which stops all the further block > >>> writes after this point. > >> > >> would it make sense to just re-use the xfs ioctl nr, if the semantics are > >> the same? > > > > The semantics are not same for now. > > In order to reuse xfs ioctl, it needs to support options for flushing logs. > > the xfs iotl has 3 behaviors optional: > > #define XFS_FSOP_GOING_FLAGS_DEFAULT 0x0 /* going down */ > #define XFS_FSOP_GOING_FLAGS_LOGFLUSH 0x1 /* flush log but not data */ > #define XFS_FSOP_GOING_FLAGS_NOLOGFLUSH 0x2 /* don't flush log nor data */ > > if f2fs currently supports a subset, you could just -EOPNOTSUPP on the others. No, just do a default shutdown operation if the semantics cannot be supported. - XFS_FSOP_GOING_FLAGS_DEFAULT == consistent on disk before shutdown + implemented by freeze/thaw/shutdown sequence - XFS_FSOP_GOING_FLAGS_LOGFLUSH == consistent journal on disk before shutdown + implemented by journal flush/shutdown sequence - XFS_FSOP_GOING_FLAGS_NOLOGFLUSH == nothing consistent on disk before shutdown + just a shutdown call. f2fs can at least support XFS_FSOP_GOING_FLAGS_DEFAULT and XFS_FSOP_GOING_FLAGS_NOLOGFLUSH.... > If the semantics are completely different, maybe it shouldn't share the > name at all. ;) The semantics are quite clear and generic - when you look at what they actually mean rather than looking at the implementation. There's no need for new ioctls here. Cheers, Dave. -- Dave Chinner david@fromorbit.com