Add a command that can replace bs in following BdrvChild structures: - qdev blk root child - block-export blk root child - any child of BlockDriverState selected by child-name Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> --- blockdev.c | 68 ++++++++++++++++++++++++++++++++++++++++++ qapi/block-core.json | 24 +++++++++++++++ stubs/blk-by-qdev-id.c | 13 ++++++++ stubs/meson.build | 1 + 4 files changed, 106 insertions(+) create mode 100644 stubs/blk-by-qdev-id.c diff --git a/blockdev.c b/blockdev.c index 2540f991b3..3082a5763c 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3681,6 +3681,74 @@ out: bdrv_drain_all_end(); } +void qmp_blockdev_replace(const char *parent, const char *child, + const char *new_child, Error **errp) +{ + BdrvChild *child_to_replace = NULL; + BlockDriverState *new_child_bs; + Error *dev_err = NULL, *exp_err = NULL; + BlockDriverState *parent_bs = bdrv_find_node(parent); + BlockBackend *dev_blk = blk_by_qdev_id(parent, &dev_err); + BlockBackend *exp_blk = blk_by_export_id(parent, &exp_err); + unsigned found = !!parent_bs + !!dev_blk + !!exp_blk; + + if (found == 0) { + error_setg(errp, "Neither device, nor export, nor block-node exist" + " with name '%s'. block-node: not found," + " device block-backend: %s, export block-backend: %s", + parent, error_get_pretty(dev_err), + error_get_pretty(exp_err)); + } + error_free(dev_err); + error_free(exp_err); + + if (found == 0) { + return; + } + + if (found > 1) { + error_setg(errp, "Parent name '%s' is ambigous: block-node %s," + " device block-backend %s, export block-backend %s", + parent, parent_bs ? "found" : "not found", + dev_blk ? "found" : "not found", + exp_blk ? "found" : "not found"); + return; + } + + if (parent_bs) { + child_to_replace = bdrv_find_child(parent_bs, child); + if (!child_to_replace) { + error_setg(errp, "Block driver node '%s' doesn't have child " + "named '%s'", parent, child); + return; + } + } else { + BlockBackend *blk = dev_blk ?: exp_blk; + + if (strcmp(child, "root")) { + error_setg(errp, "Devices and exports may have only 'root' child"); + } + + child_to_replace = blk_root(blk); + if (!child_to_replace) { + error_setg(errp, "%s '%s' is empty, nothing to replace", + dev_blk ? "Device" : "Export", parent); + return; + } + } + + assert(child_to_replace); + assert(child_to_replace->bs); + + new_child_bs = bdrv_find_node(new_child); + if (!new_child_bs) { + error_setg(errp, "Node '%s' not found", new_child); + return; + } + + bdrv_replace_child_bs(child_to_replace, new_child_bs, errp); +} + QemuOptsList qemu_common_drive_opts = { .name = "drive", .head = QTAILQ_HEAD_INITIALIZER(qemu_common_drive_opts.head), diff --git a/qapi/block-core.json b/qapi/block-core.json index b82af74256..9cc7c3d140 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -6334,3 +6334,27 @@ ## { 'struct': 'DummyBlockCoreForceArrays', 'data': { 'unused-block-graph-info': ['BlockGraphInfo'] } } + +## +# @blockdev-replace: +# +# Replace a block-node associated with device (@parent should be +# QOM path, and @child should be "root") or with block-export (@parent +# should be export name, and @child should be "root") or any child +# of block-node (@parent should be node-name, and @child should be any +# if its children names) with @new-child block-node. +# +# @parent: QOM path or block-export or node-name, which @child should +# be repalced. If several matching parents exist, the command +# will fail +# +# @child: child to replace. Must be "root" when parent is QOM path or +# block-export +# +# @new-child: node-name of the block-node, which should become a +# replacement for @child's current block-node +# +# Since 11.0 +## +{ 'command': 'blockdev-replace', + 'data': { 'parent': 'str', 'child': 'str', 'new-child': 'str' } } diff --git a/stubs/blk-by-qdev-id.c b/stubs/blk-by-qdev-id.c new file mode 100644 index 0000000000..66ead77f4d --- /dev/null +++ b/stubs/blk-by-qdev-id.c @@ -0,0 +1,13 @@ +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "system/block-backend.h" + +BlockBackend *blk_by_qdev_id(const char *id, Error **errp) +{ + /* + * We expect this when blockdev-change is called with parent-type=qdev, + * but qdev-monitor is not linked in. So no blk_ API is not available. + */ + error_setg(errp, "Parameter 'parent-type' does not accept value 'qdev'"); + return NULL; +} diff --git a/stubs/meson.build b/stubs/meson.build index d3b551f4de..93a52d273e 100644 --- a/stubs/meson.build +++ b/stubs/meson.build @@ -15,6 +15,7 @@ if have_block stub_ss.add(files('bdrv-next-monitor-owned.c')) stub_ss.add(files('blk-commit-all.c')) stub_ss.add(files('blk-exp-close-all.c')) + stub_ss.add(files('blk-by-qdev-id.c')) stub_ss.add(files('blockdev-close-all-bdrv-states.c')) stub_ss.add(files('change-state-handler.c')) stub_ss.add(files('get-vm-name.c')) -- 2.52.0