From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57056) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VjjEr-0007SA-Ep for qemu-devel@nongnu.org; Fri, 22 Nov 2013 00:25:15 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VjjEl-0004QL-EP for qemu-devel@nongnu.org; Fri, 22 Nov 2013 00:25:09 -0500 Received: from mx1.redhat.com ([209.132.183.28]:2512) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VjjEl-0004MY-6f for qemu-devel@nongnu.org; Fri, 22 Nov 2013 00:25:03 -0500 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 rAM5P1wi005757 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 22 Nov 2013 00:25:01 -0500 From: Fam Zheng Date: Fri, 22 Nov 2013 13:24:47 +0800 Message-Id: <1385097894-1380-1-git-send-email-famz@redhat.com> Subject: [Qemu-devel] [PATCH v4 0/7] Drop in_use from BlockDriverState and enable point-in-time snapshot exporting over NBD List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, hbrock@redhat.com, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com This series adds for point-in-time snapshot NBD exporting based on blockdev-backup (variant of drive-backup with existing device as target). We get a thin point-in-time snapshot by COW mechanism of drive-backup, and export it through built in NBD server. The steps are as below: 1. (SHELL) qemu-img create -f qcow2 BACKUP.qcow2 (Alternatively we can use -o backing_file=RUNNING-VM.img to omit explicitly providing the size by ourselves, but it's risky because RUNNING-VM.qcow2 is used r/w by guest. Whether or not setting backing file in the image file doesn't matter, as we are going to override the backing hd in the next step) 2. (QMP) blockdev-add backing=source-drive file.driver=file file.filename=BACKUP.qcow2 id=target0 if=none driver=qcow2 (where ide0-hd0 is the running BlockDriverState name for RUNNING-VM.img. This patch implements "backing=" option to override backing_hd for added drive) 3. (QMP) blockdev-backup device=source-drive sync=none target=target0 (this is the QMP command introduced by this series, which use a named device as target of drive-backup) 4. (QMP) nbd-server-add device=target0 When image fleecing done: 1. (QMP) block-job-complete device=ide0-hd0 2. (HMP) drive_del target0 3. (SHELL) rm BACKUP.qcow2 v4: Dropping RFC, this series tries to address the crashing cases with an added safety mechanics. In the first half of series, replace the in_use flag with an operation blocker list, and block all operations on named backing hd: [01/07] qapi: Add BlockOperationType enum [02/07] block: Introduce op_blockers to BlockDriverState [03/07] block: Replace in_use with operation blocker [04/07] block: Add checks of blocker in block operations The second half enables point in time snapshot over NBD, with fixes from last revision: [05/07] block: Parse "backing" option to reference existing BDS Fix NULL dereference if device not found. [06/07] qmp: add command 'blockdev-backup' Moved some checks into backup_run. (Paolo) [07/07] block: Allow backup on referenced named BlockDriverState New. Removes one specific blocker on backing referenced BDS, so we can start a backup job on it. v3: Base on blockdev-add. The syntax blockdev-add backing= is new: This will make referenced BDS in the middle of a backing chain, which has significant effects over all existing block operations in QMP. It needs to be reviewed and tested carefully. I'm listing the commands here that can take a device id as parameter (but may not be complete). These commands do not mutate the backing chain (not directly, at least) and should be safe: block_passwd block_set_io_throttle block-job-set-speed block-job-cancel block-job-pause block-job-resume block-job-complete drive-backup blockdev-snapshot-sync blockdev-snapshot-internal-sync blockdev-snapshot-delete-internal-sync: These should be safe. nbd-server-add These can mutates the chain (removing, closing or swapping BDS), need more work to convert them to safe operations with a BDS in the middle. device_del eject: it does bdrv_close the device. change: internally calls eject. block-commit: it deletes intermediate BDSes, which may include other named BDS. block-stream: drive-mirror: it swaps active with target when complete. Resizing a middle BDS need to be reviewed too: block_resize: TBD. Adding and backing HD referencing will put other BDS in middle, but should not immediately break things: blockdev-add Fam Zheng (7): qapi: Add BlockOperationType enum block: Introduce op_blockers to BlockDriverState block: Replace in_use with operation blocker block: Add checks of blocker in block operations block: Parse "backing" option to reference existing BDS qmp: add command 'blockdev-backup' block: Allow backup on referenced named BlockDriverState block-migration.c | 8 ++- block.c | 124 ++++++++++++++++++++++++++++++++++------ block/backup.c | 22 +++++++ blockdev-nbd.c | 4 ++ blockdev.c | 100 ++++++++++++++++++++++++++++---- blockjob.c | 12 ++-- hw/block/dataplane/virtio-blk.c | 16 ++++-- include/block/block.h | 8 ++- include/block/block_int.h | 9 ++- include/block/blockjob.h | 3 + qapi-schema.json | 74 ++++++++++++++++++++++++ qmp-commands.hx | 46 +++++++++++++++ 12 files changed, 384 insertions(+), 42 deletions(-) -- 1.8.4.2