From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45778) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WXXjv-0006qJ-Jw for qemu-devel@nongnu.org; Tue, 08 Apr 2014 11:15:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WXXjp-000608-93 for qemu-devel@nongnu.org; Tue, 08 Apr 2014 11:15:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:2629) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WXXjp-000603-0y for qemu-devel@nongnu.org; Tue, 08 Apr 2014 11:15:01 -0400 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s38FF0Je027112 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 8 Apr 2014 11:15:00 -0400 Date: Tue, 8 Apr 2014 17:14:58 +0200 From: Kevin Wolf Message-ID: <20140408151458.GE6262@noname.str.redhat.com> References: <1396961442-24046-1-git-send-email-mreitz@redhat.com> <1396961442-24046-4-git-send-email-mreitz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1396961442-24046-4-git-send-email-mreitz@redhat.com> Subject: Re: [Qemu-devel] [PATCH v2 3/6] qemu-img: Implement commit like QMP List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Max Reitz Cc: qemu-devel@nongnu.org, Stefan Hajnoczi Am 08.04.2014 um 14:50 hat Max Reitz geschrieben: > qemu-img should use QMP commands whenever possible in order to ensure > feature completeness of both online and offline image operations. As > qemu-img itself has no access to QMP (since this would basically require > just everything being linked into qemu-img), imitate QMP's > implementation of block-commit by using commit_active_start() and then > waiting for the block job to finish. Leaves us with the HMP commit command that uses the old bdrv_commit() function. I wonder if we can get rid of it by letting the HMP command stop the VM, do a live commit, and then restart the VM. > This new implementation does not empty the snapshot image, as opposed to > the old implementation using bdrv_commit(). However, as QMP's > block-commit apparently never did this and as qcow2 (which is probably > qemu's standard image format) does not even implement the required > function (bdrv_make_empty()), it does not seem necessary. In fact, I think since qcow2 has discard support it would actually be possible to write a sensible implementation of bdrv_make_empty(). That's a separate feature, though, and can go in a different patch series. > Signed-off-by: Max Reitz > --- > block/Makefile.objs | 2 +- > qemu-img.c | 70 ++++++++++++++++++++++++++++++++++++++--------------- > 2 files changed, 52 insertions(+), 20 deletions(-) > > diff --git a/block/Makefile.objs b/block/Makefile.objs > index fd88c03..2c37e80 100644 > --- a/block/Makefile.objs > +++ b/block/Makefile.objs > @@ -9,6 +9,7 @@ block-obj-y += snapshot.o qapi.o > block-obj-$(CONFIG_WIN32) += raw-win32.o win32-aio.o > block-obj-$(CONFIG_POSIX) += raw-posix.o > block-obj-$(CONFIG_LINUX_AIO) += linux-aio.o > +block-obj-y += mirror.o > > ifeq ($(CONFIG_POSIX),y) > block-obj-y += nbd.o nbd-client.o sheepdog.o > @@ -22,7 +23,6 @@ endif > > common-obj-y += stream.o > common-obj-y += commit.o > -common-obj-y += mirror.o > common-obj-y += backup.o > > iscsi.o-cflags := $(LIBISCSI_CFLAGS) > diff --git a/qemu-img.c b/qemu-img.c > index 8455994..e86911f 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -30,6 +30,7 @@ > #include "qemu/osdep.h" > #include "sysemu/sysemu.h" > #include "block/block_int.h" > +#include "block/blockjob.h" > #include "block/qapi.h" > #include > > @@ -682,12 +683,37 @@ fail: > return ret; > } > > +static void dummy_block_job_cb(void *opaque, int ret) > +{ > +} Why don't we need to check the return value? Kevin