From c6c40cc92fbb91d704d3739bb78bfd936f111625 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Tue, 4 Feb 2025 22:13:59 +0100 Subject: [PATCH 15/23] block: Add blockdev-set-active QMP command RH-Author: Kevin Wolf RH-MergeRequest: 339: QMP command for block device reactivation after migration RH-Jira: RHEL-54296 RHEL-78397 RH-Acked-by: Eric Blake RH-Acked-by: Stefan Hajnoczi RH-Commit: [14/22] e494fb6df6c363b6266e5fb7d09c31b3e7694f04 (kmwolf/centos-qemu-kvm) The system emulator tries to automatically activate and inactivate block nodes at the right point during migration. However, there are still cases where it's necessary that the user can do this manually. Images are only activated on the destination VM of a migration when the VM is actually resumed. If the VM was paused, this doesn't happen automatically. The user may want to perform some operation on a block device (e.g. taking a snapshot or starting a block job) without also resuming the VM yet. This is an example where a manual command is necessary. Another example is VM migration when the image files are opened by an external qemu-storage-daemon instance on each side. In this case, the process that needs to hand over the images isn't even part of the migration and can't know when the migration completes. Management tools need a way to explicitly inactivate images on the source and activate them on the destination. This adds a new blockdev-set-active QMP command that lets the user change the status of individual nodes (this is necessary in qemu-storage-daemon because it could be serving multiple VMs and only one of them migrates at a time). For convenience, operating on all devices (like QEMU does automatically during migration) is offered as an option, too, and can be used in the context of single VM. Signed-off-by: Kevin Wolf Acked-by: Fabiano Rosas Reviewed-by: Eric Blake Reviewed-by: Stefan Hajnoczi Message-ID: <20250204211407.381505-9-kwolf@redhat.com> Signed-off-by: Kevin Wolf (cherry picked from commit 8cd37207f8a90c5f995283ecf95f1cb5f7518a77) Signed-off-by: Kevin Wolf --- block.c | 21 ++++++++++++++++++++ blockdev.c | 32 ++++++++++++++++++++++++++++++ include/block/block-global-state.h | 3 +++ qapi/block-core.json | 32 ++++++++++++++++++++++++++++++ 4 files changed, 88 insertions(+) diff --git a/block.c b/block.c index fd2ac177ef..2140a5d3b7 100644 --- a/block.c +++ b/block.c @@ -7052,6 +7052,27 @@ bdrv_inactivate_recurse(BlockDriverState *bs, bool top_level) return 0; } +int bdrv_inactivate(BlockDriverState *bs, Error **errp) +{ + int ret; + + GLOBAL_STATE_CODE(); + GRAPH_RDLOCK_GUARD_MAINLOOP(); + + if (bdrv_has_bds_parent(bs, true)) { + error_setg(errp, "Node has active parent node"); + return -EPERM; + } + + ret = bdrv_inactivate_recurse(bs, true); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to inactivate node"); + return ret; + } + + return 0; +} + int bdrv_inactivate_all(void) { BlockDriverState *bs = NULL; diff --git a/blockdev.c b/blockdev.c index 81430122df..70046b6690 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3468,6 +3468,38 @@ void qmp_blockdev_del(const char *node_name, Error **errp) bdrv_unref(bs); } +void qmp_blockdev_set_active(const char *node_name, bool active, Error **errp) +{ + int ret; + + GLOBAL_STATE_CODE(); + GRAPH_RDLOCK_GUARD_MAINLOOP(); + + if (!node_name) { + if (active) { + bdrv_activate_all(errp); + } else { + ret = bdrv_inactivate_all(); + if (ret < 0) { + error_setg_errno(errp, -ret, "Failed to inactivate all nodes"); + } + } + } else { + BlockDriverState *bs = bdrv_find_node(node_name); + if (!bs) { + error_setg(errp, "Failed to find node with node-name='%s'", + node_name); + return; + } + + if (active) { + bdrv_activate(bs, errp); + } else { + bdrv_inactivate(bs, errp); + } + } +} + static BdrvChild * GRAPH_RDLOCK bdrv_find_child(BlockDriverState *parent_bs, const char *child_name) { diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h index a826bf5f78..9be34b3c99 100644 --- a/include/block/block-global-state.h +++ b/include/block/block-global-state.h @@ -184,6 +184,9 @@ bdrv_activate(BlockDriverState *bs, Error **errp); int coroutine_fn no_co_wrapper_bdrv_rdlock bdrv_co_activate(BlockDriverState *bs, Error **errp); +int no_coroutine_fn +bdrv_inactivate(BlockDriverState *bs, Error **errp); + void bdrv_activate_all(Error **errp); int bdrv_inactivate_all(void); diff --git a/qapi/block-core.json b/qapi/block-core.json index 6ec603aa6f..c1af3d1f7d 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -4930,6 +4930,38 @@ { 'command': 'blockdev-del', 'data': { 'node-name': 'str' }, 'allow-preconfig': true } +## +# @blockdev-set-active: +# +# Activate or inactivate a block device. Use this to manage the handover of +# block devices on migration with qemu-storage-daemon. +# +# Activating a node automatically activates all of its child nodes first. +# Inactivating a node automatically inactivates any of its child nodes that are +# not in use by a still active node. +# +# @node-name: Name of the graph node to activate or inactivate. By default, all +# nodes are affected by the operation. +# +# @active: true if the nodes should be active when the command returns success, +# false if they should be inactive. +# +# Since: 10.0 +# +# .. qmp-example:: +# +# -> { "execute": "blockdev-set-active", +# "arguments": { +# "node-name": "node0", +# "active": false +# } +# } +# <- { "return": {} } +## +{ 'command': 'blockdev-set-active', + 'data': { '*node-name': 'str', 'active': 'bool' }, + 'allow-preconfig': true } + ## # @BlockdevCreateOptionsFile: # -- 2.48.1