block/monitor/block-hmp-cmds.c | 4 ++-- block/qapi.c | 9 +++++---- qapi/block-core.json | 4 ++++ ui/cocoa.m | 2 +- 4 files changed, 12 insertions(+), 7 deletions(-)
From: Peter Krempa <pkrempa@redhat.com>
Some time ago (commit facda5443f5a8) I've added 'flat' mode (which
omits 'backing-image' key in reply) to 'query-named-block-nodes' to
minimize the size of the returned JSON for deeper backing chains.
While 'query-block' behaved slightly better it turns out that in libvirt
we do call 'query-block' to figure out some information about the
block device (e.g. throttling info) but we don't look at the backing
chain itself.
Wire up 'flat' for 'query-block' so that libvirt can ask for an
abbreviated output. The implementation is much simpler as the internals
are shared with 'query-named-block-nodes'.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
block/monitor/block-hmp-cmds.c | 4 ++--
block/qapi.c | 9 +++++----
qapi/block-core.json | 4 ++++
ui/cocoa.m | 2 +-
4 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index 3640d1f3dc..d301f56a39 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -422,7 +422,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
/* Then try adding all block devices. If one fails, close all and
* exit.
*/
- block_list = qmp_query_block(NULL);
+ block_list = qmp_query_block(false, false, NULL);
for (info = block_list; info; info = info->next) {
if (!info->value->inserted) {
@@ -741,7 +741,7 @@ void hmp_info_block(Monitor *mon, const QDict *qdict)
/* Print BlockBackend information */
if (!nodes) {
- block_list = qmp_query_block(NULL);
+ block_list = qmp_query_block(false, false, NULL);
} else {
block_list = NULL;
}
diff --git a/block/qapi.c b/block/qapi.c
index 9f5771e019..2fc38d67a0 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -456,7 +456,7 @@ fail:
/* @p_info will be set only on success. */
static void GRAPH_RDLOCK
-bdrv_query_info(BlockBackend *blk, BlockInfo **p_info, Error **errp)
+bdrv_query_info(BlockBackend *blk, bool flat, BlockInfo **p_info, Error **errp)
{
BlockInfo *info = g_malloc0(sizeof(*info));
BlockDriverState *bs = blk_bs(blk);
@@ -488,7 +488,7 @@ bdrv_query_info(BlockBackend *blk, BlockInfo **p_info, Error **errp)
}
if (bs && bs->drv) {
- info->inserted = bdrv_block_device_info(blk, bs, false, errp);
+ info->inserted = bdrv_block_device_info(blk, bs, flat, errp);
if (info->inserted == NULL) {
goto err;
}
@@ -698,11 +698,12 @@ bdrv_query_bds_stats(BlockDriverState *bs, bool blk_level)
return s;
}
-BlockInfoList *qmp_query_block(Error **errp)
+BlockInfoList *qmp_query_block(bool has_flat, bool flat, Error **errp)
{
BlockInfoList *head = NULL, **p_next = &head;
BlockBackend *blk;
Error *local_err = NULL;
+ bool return_flat = has_flat && flat;
GRAPH_RDLOCK_GUARD_MAINLOOP();
@@ -714,7 +715,7 @@ BlockInfoList *qmp_query_block(Error **errp)
}
info = g_malloc0(sizeof(*info));
- bdrv_query_info(blk, &info->value, &local_err);
+ bdrv_query_info(blk, return_flat, &info->value, &local_err);
if (local_err) {
error_propagate(errp, local_err);
g_free(info);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index b82af74256..e89d878544 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -855,6 +855,9 @@
#
# Get a list of `BlockInfo` for all virtual block devices.
#
+# @flat: Omit the nested data about backing image ("backing-image"
+# key) if true. Default is false (Since 11.0)
+#
# Returns: a list describing each virtual block device. Filter nodes
# that were created implicitly are skipped over.
#
@@ -945,6 +948,7 @@
# }
##
{ 'command': 'query-block', 'returns': ['BlockInfo'],
+ 'data': { '*flat': 'bool' },
'allow-preconfig': true }
##
diff --git a/ui/cocoa.m b/ui/cocoa.m
index 23b7a736d7..5b21fe3aea 100644
--- a/ui/cocoa.m
+++ b/ui/cocoa.m
@@ -1849,7 +1849,7 @@ static void addRemovableDevicesMenuItems(void)
BlockInfoList *currentDevice, *pointerToFree;
NSString *deviceName;
- currentDevice = qmp_query_block(NULL);
+ currentDevice = qmp_query_block(false, false, NULL);
pointerToFree = currentDevice;
menu = [[[NSApp mainMenu] itemWithTitle:@"Machine"] submenu];
--
2.52.0Peter Krempa <pkrempa@redhat.com> writes:
> From: Peter Krempa <pkrempa@redhat.com>
>
> Some time ago (commit facda5443f5a8) I've added 'flat' mode (which
> omits 'backing-image' key in reply) to 'query-named-block-nodes' to
> minimize the size of the returned JSON for deeper backing chains.
Almost six years. Time flies :)
> While 'query-block' behaved slightly better it turns out that in libvirt
> we do call 'query-block' to figure out some information about the
> block device (e.g. throttling info) but we don't look at the backing
> chain itself.
>
> Wire up 'flat' for 'query-block' so that libvirt can ask for an
> abbreviated output. The implementation is much simpler as the internals
> are shared with 'query-named-block-nodes'.
>
> Signed-off-by: Peter Krempa <pkrempa@redhat.com>
> ---
> block/monitor/block-hmp-cmds.c | 4 ++--
> block/qapi.c | 9 +++++----
> qapi/block-core.json | 4 ++++
> ui/cocoa.m | 2 +-
> 4 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
> index 3640d1f3dc..d301f56a39 100644
> --- a/block/monitor/block-hmp-cmds.c
> +++ b/block/monitor/block-hmp-cmds.c
> @@ -422,7 +422,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
> /* Then try adding all block devices. If one fails, close all and
> * exit.
> */
> - block_list = qmp_query_block(NULL);
> + block_list = qmp_query_block(false, false, NULL);
Is info->value->inserted->image->backing_image used here?
If not, we can pass true and save allocations. Thought, not a demand.
Same for the other calls.
>
> for (info = block_list; info; info = info->next) {
> if (!info->value->inserted) {
> @@ -741,7 +741,7 @@ void hmp_info_block(Monitor *mon, const QDict *qdict)
>
> /* Print BlockBackend information */
> if (!nodes) {
> - block_list = qmp_query_block(NULL);
> + block_list = qmp_query_block(false, false, NULL);
> } else {
> block_list = NULL;
> }
> diff --git a/block/qapi.c b/block/qapi.c
> index 9f5771e019..2fc38d67a0 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -456,7 +456,7 @@ fail:
>
> /* @p_info will be set only on success. */
> static void GRAPH_RDLOCK
> -bdrv_query_info(BlockBackend *blk, BlockInfo **p_info, Error **errp)
> +bdrv_query_info(BlockBackend *blk, bool flat, BlockInfo **p_info, Error **errp)
> {
> BlockInfo *info = g_malloc0(sizeof(*info));
> BlockDriverState *bs = blk_bs(blk);
> @@ -488,7 +488,7 @@ bdrv_query_info(BlockBackend *blk, BlockInfo **p_info, Error **errp)
> }
>
> if (bs && bs->drv) {
> - info->inserted = bdrv_block_device_info(blk, bs, false, errp);
> + info->inserted = bdrv_block_device_info(blk, bs, flat, errp);
> if (info->inserted == NULL) {
> goto err;
> }
> @@ -698,11 +698,12 @@ bdrv_query_bds_stats(BlockDriverState *bs, bool blk_level)
> return s;
> }
>
> -BlockInfoList *qmp_query_block(Error **errp)
> +BlockInfoList *qmp_query_block(bool has_flat, bool flat, Error **errp)
> {
> BlockInfoList *head = NULL, **p_next = &head;
> BlockBackend *blk;
> Error *local_err = NULL;
> + bool return_flat = has_flat && flat;
>
> GRAPH_RDLOCK_GUARD_MAINLOOP();
>
> @@ -714,7 +715,7 @@ BlockInfoList *qmp_query_block(Error **errp)
> }
>
> info = g_malloc0(sizeof(*info));
> - bdrv_query_info(blk, &info->value, &local_err);
> + bdrv_query_info(blk, return_flat, &info->value, &local_err);
> if (local_err) {
> error_propagate(errp, local_err);
> g_free(info);
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index b82af74256..e89d878544 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -855,6 +855,9 @@
> #
> # Get a list of `BlockInfo` for all virtual block devices.
> #
> +# @flat: Omit the nested data about backing image ("backing-image"
> +# key) if true. Default is false (Since 11.0)
> +#
The "backing-image" key is actually BlockInfo member inserted member
image member backing-image. This is even more deeply nested than for
query-named-block-nodes. Doc text good enough?
> # Returns: a list describing each virtual block device. Filter nodes
> # that were created implicitly are skipped over.
> #
> @@ -945,6 +948,7 @@
> # }
> ##
> { 'command': 'query-block', 'returns': ['BlockInfo'],
> + 'data': { '*flat': 'bool' },
> 'allow-preconfig': true }
>
> ##
QAPI schema
Acked-by: Markus Armbruster <armbru@redhat.com>
> diff --git a/ui/cocoa.m b/ui/cocoa.m
> index 23b7a736d7..5b21fe3aea 100644
> --- a/ui/cocoa.m
> +++ b/ui/cocoa.m
> @@ -1849,7 +1849,7 @@ static void addRemovableDevicesMenuItems(void)
> BlockInfoList *currentDevice, *pointerToFree;
> NSString *deviceName;
>
> - currentDevice = qmp_query_block(NULL);
> + currentDevice = qmp_query_block(false, false, NULL);
> pointerToFree = currentDevice;
>
> menu = [[[NSApp mainMenu] itemWithTitle:@"Machine"] submenu];
On Mon, Jan 12, 2026 at 11:29:24 +0100, Markus Armbruster wrote:
> Peter Krempa <pkrempa@redhat.com> writes:
>
> > From: Peter Krempa <pkrempa@redhat.com>
> >
> > Some time ago (commit facda5443f5a8) I've added 'flat' mode (which
> > omits 'backing-image' key in reply) to 'query-named-block-nodes' to
> > minimize the size of the returned JSON for deeper backing chains.
>
> Almost six years. Time flies :)
Indeed! Actually last year (already) I've deleted the corresponding
capability since libvirt now only supports QEMUs which do support this
:D
>
> > While 'query-block' behaved slightly better it turns out that in libvirt
> > we do call 'query-block' to figure out some information about the
> > block device (e.g. throttling info) but we don't look at the backing
> > chain itself.
> >
> > Wire up 'flat' for 'query-block' so that libvirt can ask for an
> > abbreviated output. The implementation is much simpler as the internals
> > are shared with 'query-named-block-nodes'.
> >
> > Signed-off-by: Peter Krempa <pkrempa@redhat.com>
> > ---
> > block/monitor/block-hmp-cmds.c | 4 ++--
> > block/qapi.c | 9 +++++----
> > qapi/block-core.json | 4 ++++
> > ui/cocoa.m | 2 +-
> > 4 files changed, 12 insertions(+), 7 deletions(-)
> >
> > diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
> > index 3640d1f3dc..d301f56a39 100644
> > --- a/block/monitor/block-hmp-cmds.c
> > +++ b/block/monitor/block-hmp-cmds.c
> > @@ -422,7 +422,7 @@ void hmp_nbd_server_start(Monitor *mon, const QDict *qdict)
> > /* Then try adding all block devices. If one fails, close all and
> > * exit.
> > */
> > - block_list = qmp_query_block(NULL);
> > + block_list = qmp_query_block(false, false, NULL);
>
> Is info->value->inserted->image->backing_image used here?
>
> If not, we can pass true and save allocations. Thought, not a demand.
It's not used in hmp_nbd_server_start. I'll do a separate patch for it
as it's simple enough, but IMO not related to this patch which should
keep behaviour of unrelated code.
> Same for the other calls.
>
> >
> > for (info = block_list; info; info = info->next) {
> > if (!info->value->inserted) {
> > @@ -741,7 +741,7 @@ void hmp_info_block(Monitor *mon, const QDict *qdict)
... but this one does use it (although for questionably useful
information: first backing image name and the depth of the backing chain).
[...]
> > diff --git a/qapi/block-core.json b/qapi/block-core.json
> > index b82af74256..e89d878544 100644
> > --- a/qapi/block-core.json
> > +++ b/qapi/block-core.json
> > @@ -855,6 +855,9 @@
> > #
> > # Get a list of `BlockInfo` for all virtual block devices.
> > #
> > +# @flat: Omit the nested data about backing image ("backing-image"
> > +# key) if true. Default is false (Since 11.0)
> > +#
>
> The "backing-image" key is actually BlockInfo member inserted member
> image member backing-image. This is even more deeply nested than for
> query-named-block-nodes. Doc text good enough?
Hmm, how about:
+# @flat: Omit the nested data about backing image (Omitted are contents of
+# 'backing-image' key of the 'ImageInfo' struct which is returned
+# as 'image' key of 'BlockDeviceInfo' struct returned as 'inserted' key
+# in 'BlockInfo' struct returned by this command).
or
+# @flat: Omit the nested data about backing image (Omitted are contents
+# of 'BlockInfo'->inserted->image->backing-image).
?
On Thu, Dec 11, 2025 at 10:37:53 +0100, Peter Krempa wrote: > From: Peter Krempa <pkrempa@redhat.com> > > Some time ago (commit facda5443f5a8) I've added 'flat' mode (which > omits 'backing-image' key in reply) to 'query-named-block-nodes' to > minimize the size of the returned JSON for deeper backing chains. > > While 'query-block' behaved slightly better it turns out that in libvirt > we do call 'query-block' to figure out some information about the > block device (e.g. throttling info) but we don't look at the backing > chain itself. > > Wire up 'flat' for 'query-block' so that libvirt can ask for an > abbreviated output. The implementation is much simpler as the internals > are shared with 'query-named-block-nodes'. > > Signed-off-by: Peter Krempa <pkrempa@redhat.com> > --- > block/monitor/block-hmp-cmds.c | 4 ++-- > block/qapi.c | 9 +++++---- > qapi/block-core.json | 4 ++++ > ui/cocoa.m | 2 +- > 4 files changed, 12 insertions(+), 7 deletions(-) Ping
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