block: Add 'active' field to BlockDeviceInfo

This allows querying from QMP (and also HMP) whether an image is
currently active or inactive (in the sense of BDRV_O_INACTIVE).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20250204211407.381505-2-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

block.c

@@ -6824,6 +6824,10 @@ void bdrv_init_with_whitelist(void)
     bdrv_init();
 }
 
+bool bdrv_is_inactive(BlockDriverState *bs) {
+    return bs->open_flags & BDRV_O_INACTIVE;
+}
+
 int bdrv_activate(BlockDriverState *bs, Error **errp)
 {
     BdrvChild *child, *parent;

block/monitor/block-hmp-cmds.c

@@ -630,11 +630,12 @@ static void print_block_info(Monitor *mon, BlockInfo *info,
     }
 
     if (inserted) {
-        monitor_printf(mon, ": %s (%s%s%s)\n",
+        monitor_printf(mon, ": %s (%s%s%s%s)\n",
                        inserted->file,
                        inserted->drv,
                        inserted->ro ? ", read-only" : "",
-                       inserted->encrypted ? ", encrypted" : "");
+                       inserted->encrypted ? ", encrypted" : "",
+                       inserted->active ? "" : ", inactive");
     } else {
         monitor_printf(mon, ": [not inserted]\n");
     }

block/qapi.c

@@ -63,6 +63,7 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
     info->file                   = g_strdup(bs->filename);
     info->ro                     = bdrv_is_read_only(bs);
     info->drv                    = g_strdup(bs->drv->format_name);
+    info->active                 = !bdrv_is_inactive(bs);
     info->encrypted              = bs->encrypted;
 
     info->cache = g_new(BlockdevCacheInfo, 1);

include/block/block-global-state.h

@@ -175,6 +175,9 @@ BlockDriverState * GRAPH_RDLOCK
 check_to_replace_node(BlockDriverState *parent_bs, const char *node_name,
                       Error **errp);
 
+
+bool GRAPH_RDLOCK bdrv_is_inactive(BlockDriverState *bs);
+
 int no_coroutine_fn GRAPH_RDLOCK
 bdrv_activate(BlockDriverState *bs, Error **errp);
 

qapi/block-core.json

@@ -486,6 +486,10 @@
 # @backing_file_depth: number of files in the backing file chain
 #     (since: 1.2)
 #
+# @active: true if the backend is active; typical cases for inactive backends
+#     are on the migration source instance after migration completes and on the
+#     destination before it completes. (since: 10.0)
+#
 # @encrypted: true if the backing device is encrypted
 #
 # @detect_zeroes: detect and optimize zero writes (Since 2.1)
@@ -556,7 +560,7 @@
 { 'struct': 'BlockDeviceInfo',
   'data': { 'file': 'str', '*node-name': 'str', 'ro': 'bool', 'drv': 'str',
             '*backing_file': 'str', 'backing_file_depth': 'int',
-            'encrypted': 'bool',
+            'active': 'bool', 'encrypted': 'bool',
             'detect_zeroes': 'BlockdevDetectZeroesOptions',
             'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int',
             'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int',

tests/qemu-iotests/184.out

@@ -26,6 +26,7 @@ Testing:
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 1073741824,
@@ -59,6 +60,7 @@ Testing:
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 1073741824,
                 "filename": "null-co://",

tests/qemu-iotests/191.out

@@ -114,6 +114,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 67108864,
@@ -155,6 +156,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT.ovl2",
@@ -183,6 +185,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 67108864,
@@ -224,6 +227,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT",
@@ -252,6 +256,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 67108864,
@@ -293,6 +298,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 393216,
                 "filename": "TEST_DIR/t.IMGFMT.mid",
@@ -321,6 +327,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 67108864,
                 "filename": "TEST_DIR/t.IMGFMT.base",
@@ -350,6 +357,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 393216,
                 "filename": "TEST_DIR/t.IMGFMT.base",
@@ -521,6 +529,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 67108864,
@@ -562,6 +571,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT.ovl2",
@@ -590,6 +600,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "backing-image": {
@@ -642,6 +653,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT.ovl3",
@@ -670,6 +682,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 67108864,
                 "filename": "TEST_DIR/t.IMGFMT.base",
@@ -699,6 +712,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 393216,
                 "filename": "TEST_DIR/t.IMGFMT.base",
@@ -727,6 +741,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 67108864,
@@ -768,6 +783,7 @@ wrote 65536/65536 bytes at offset 1048576
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT",

tests/qemu-iotests/273.out

@@ -23,6 +23,7 @@ Testing: -blockdev file,node-name=base,filename=TEST_DIR/t.IMGFMT.base -blockdev
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "backing-image": {
@@ -74,6 +75,7 @@ Testing: -blockdev file,node-name=base,filename=TEST_DIR/t.IMGFMT.base -blockdev
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT",
@@ -102,6 +104,7 @@ Testing: -blockdev file,node-name=base,filename=TEST_DIR/t.IMGFMT.base -blockdev
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "backing-image": {
                     "virtual-size": 197120,
@@ -142,6 +145,7 @@ Testing: -blockdev file,node-name=base,filename=TEST_DIR/t.IMGFMT.base -blockdev
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT.mid",
@@ -170,6 +174,7 @@ Testing: -blockdev file,node-name=base,filename=TEST_DIR/t.IMGFMT.base -blockdev
         {
             "iops_rd": 0,
             "detect_zeroes": "off",
+            "active": true,
             "image": {
                 "virtual-size": 197120,
                 "filename": "TEST_DIR/t.IMGFMT.base",