From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38185) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eRe3V-0005j4-JB for qemu-devel@nongnu.org; Wed, 20 Dec 2017 08:05:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eRe3R-0003o6-AU for qemu-devel@nongnu.org; Wed, 20 Dec 2017 08:05:05 -0500 Date: Wed, 20 Dec 2017 14:04:40 +0100 From: Kevin Wolf Message-ID: <20171220130440.GB6374@localhost.localdomain> References: <20171220103412.13048-1-kwolf@redhat.com> <20171220103412.13048-17-kwolf@redhat.com> <974e7f62-412a-21e8-d502-a0e7a99015cc@redhat.com> <20171220111822.GA6374@localhost.localdomain> <09b75421-21f1-5e9e-8f2e-c9189ab207eb@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <09b75421-21f1-5e9e-8f2e-c9189ab207eb@redhat.com> Subject: Re: [Qemu-devel] [Qemu-block] [PATCH 16/19] block: Allow graph changes in subtree drained section List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: famz@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org Am 20.12.2017 um 12:31 hat Paolo Bonzini geschrieben: > On 20/12/2017 12:18, Kevin Wolf wrote: > > Am 20.12.2017 um 11:51 hat Paolo Bonzini geschrieben: > >> On 20/12/2017 11:34, Kevin Wolf wrote: > >>> .inherit_options = bdrv_inherited_options, > >>> .drained_begin = bdrv_child_cb_drained_begin, > >>> .drained_end = bdrv_child_cb_drained_end, > >>> + .attach = bdrv_child_cb_attach, > >>> + .detach = bdrv_child_cb_detach, > >>> .inactivate = bdrv_child_cb_inactivate, > >>> }; > >>> > >>> @@ -911,6 +933,8 @@ const BdrvChildRole child_format = { > >>> .inherit_options = bdrv_inherited_fmt_options, > >>> .drained_begin = bdrv_child_cb_drained_begin, > >>> .drained_end = bdrv_child_cb_drained_end, > >>> + .attach = bdrv_child_cb_attach, > >>> + .detach = bdrv_child_cb_detach, > >>> .inactivate = bdrv_child_cb_inactivate, > >> > >> Is there any case of a BdrvChildRole that doesn't want these callbacks? > >> Maybe the functions should be called after ->attach and before ->detach > >> (e.g. bdrv_{,un}apply_subtree_drain), rather than modifying the > >> BdrvChildRole implementations. > > > > At first I intended to implement it directly in > > bdrv_replace_child_noperm(), but the thing is that you need the > > bs->recursive_quiesce_counter of the parent BDS - but not all parents of > > a BdrvChild are even a BDS. It could also be a BB root child or a block > > job child. This is why we only have a void *opaque rather than a BDS > > pointer for the parent. > > > > The other option would be an additional BdrvChildRole callback like > > .get_recursive_quiesce_counter, but compared to that, I like some code > > in .attach/.detach better. > > I see. What about keeping the callbacks, but exporting > > void bdrv_apply_subtree_drain(BlockDriverState *child, > BlockDriverState *new_parent); > void bdrv_unapply_subtree_drain(BlockDriverState *child, > BlockDriverState *old_parent); > > instead of bdrv_do_drained_{begin,end}? Sure, that can be done. (BdrvChild *child, though.) Kevin