From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57192) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YucWM-00085p-D3 for qemu-devel@nongnu.org; Tue, 19 May 2015 04:05:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YucWL-0008VD-FV for qemu-devel@nongnu.org; Tue, 19 May 2015 04:05:02 -0400 Sender: Paolo Bonzini Message-ID: <555AEEA3.4080407@redhat.com> Date: Tue, 19 May 2015 10:04:51 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1432036186-29903-1-git-send-email-famz@redhat.com> <1432036186-29903-14-git-send-email-famz@redhat.com> In-Reply-To: <1432036186-29903-14-git-send-email-famz@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v4 13/13] block/mirror: Block "device IO" during mirror exit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, "Michael S. Tsirkin" , Juan Quintela , mreitz@redhat.com, Stefan Hajnoczi , Amit Shah On 19/05/2015 13:49, Fam Zheng wrote: > When block job mirror is finished, the source and target is synced. But > we call bdrv_swap() later in main loop bh. If the guest write before > that, target will not get the new data. This is too late. As a rule, the blocker must be established before calling bdrv_drain, and removed on the next yield (in this case, before the assignment to last_pause_ns). Paolo > Reported-by: Wen Congyang > Signed-off-by: Fam Zheng > --- > block/mirror.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/block/mirror.c b/block/mirror.c > index 58f391a..d96403b 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -320,6 +320,8 @@ static void mirror_drain(MirrorBlockJob *s) > > typedef struct { > int ret; > + /* Use to pause device IO during mirror exit */ > + Error *blocker; > } MirrorExitData; > > static void mirror_exit(BlockJob *job, void *opaque) > @@ -328,6 +330,8 @@ static void mirror_exit(BlockJob *job, void *opaque) > MirrorExitData *data = opaque; > AioContext *replace_aio_context = NULL; > > + bdrv_op_unblock(s->common.bs, BLOCK_OP_TYPE_DEVICE_IO, data->blocker); > + error_free(data->blocker); > if (s->to_replace) { > replace_aio_context = bdrv_get_aio_context(s->to_replace); > aio_context_acquire(replace_aio_context); > @@ -563,8 +567,10 @@ immediate_exit: > bdrv_release_dirty_bitmap(bs, s->dirty_bitmap); > bdrv_iostatus_disable(s->target); > > - data = g_malloc(sizeof(*data)); > + data = g_malloc0(sizeof(*data)); > data->ret = ret; > + error_setg(&data->blocker, "mirror job exiting"); > + bdrv_op_block(bs, BLOCK_OP_TYPE_DEVICE_IO, data->blocker); > block_job_defer_to_main_loop(&s->common, mirror_exit, data); > } > >