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user-level: 0.923
register: 0.921
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arm: 0.870
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socket: 0.831
files: 0.821
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vnc: 0.790
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mistranslation: 0.772
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risc-v: 0.754
KVM: 0.742
x86: 0.627
VMM: 0.620
i386: 0.550

blockdev-del doesn't work after blockdev-backup with incremental, which using dirty-bitmap
Description of problem:
After incremental backup with bitmap, blockdev-del doesn't work at target node.  
Because of this, incremental backup cannot rebase to base node.  
I refered this. https://qemu-project.gitlab.io/qemu/interop/bitmaps.html#example-incremental-push-backups-without-backing-files
Steps to reproduce:
1. `blockdev-add` incremental backup node
```
echo '{"execute":"qmp_capabilities"}{"execute":"blockdev-add","arguments":{"driver":"qcow2","node-name":"incre0","file":{"driver":"file","filename":"/mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/incre0.qcow2"}}}' | nc -U /mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/qmp.sock -N

{
    "return": {
    }
}
```
2. `blockdev-backup` with `vda` to target `incre0` node
```
echo '{"execute":"qmp_capabilities"}{"execute":"blockdev-backup", "arguments": {"device": "vda", "bitmap":"bitmap0", "target": "incre0", "sync": "incremental", "job-id": "incre0-job", "speed": 536870912}}' | nc -U /mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/qmp.sock -N

{
    "timestamp": {
        "seconds": 1651050066,
        "microseconds": 848370
    },
    "event": "JOB_STATUS_CHANGE",
    "data": {
        "status": "created",
        "id": "incre0-job"
    }
}
{
    "timestamp": {
        "seconds": 1651050066,
        "microseconds": 848431
    },
    "event": "JOB_STATUS_CHANGE",
    "data": {
        "status": "running",
        "id": "incre0-job"
    }
}
{
    "timestamp": {
        "seconds": 1651050066,
        "microseconds": 848464
    },
    "event": "JOB_STATUS_CHANGE",
    "data": {
        "status": "paused",
        "id": "incre0-job"
    }
}
{
    "timestamp": {
        "seconds": 1651050066,
        "microseconds": 848485
    },
    "event": "JOB_STATUS_CHANGE",
    "data": {
        "status": "running",
        "id": "incre0-job"
    }
}
{
    "return": {
    }
}

```
3. `query-block-jobs` check `incre0-job` is done
```
echo '{"execute":"qmp_capabilities"}{"execute":"query-block-jobs"}' | nc -U /mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/qmp.sock -N

{
    "return": {
    }
}
{
    "return": [
    ]
}
```
4. To release write lock (need to rebase in incre0.qcow2), `blockdev-del`
```
echo '{"execute":"qmp_capabilities"}{"execute":"blockdev-del","arguments":{"node-name":"incre0"}' | nc -U /mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/qmp.sock -N

{
    "return": {
    }
}
```
5. `qemu-img rebase`
```
qemu-img rebase -b base.qcow2 -u incre0.qcow2

qemu-img: Could not open 'incre0.qcow2': Failed to get "write" lock
Is another process using the image [incre0.qcow2]?
```

6. check `query-named-block-nodes` after `blockdev-del`
```
{
    "return": [
        {
            "iops_rd": 0,
            "detect_zeroes": "off",
            "image": {
                "virtual-size": 53687091200,
                "filename": "/mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/incre0.qcow2",
                "cluster-size": 65536,
                "format": "qcow2",
                "actual-size": 241340416,
                "format-specific": {
                    "type": "qcow2",
                    "data": {
                        "compat": "1.1",
                        "compression-type": "zlib",
                        "lazy-refcounts": false,
                        "refcount-bits": 16,
                        "corrupt": false,
                        "extended-l2": false
                    }
                },
                "dirty-flag": false
            },
            "iops_wr": 0,
            "ro": false,
            "node-name": "incre0",
            "backing_file_depth": 0,
            "drv": "qcow2",
            "iops": 0,
            "bps_wr": 0,
            "write_threshold": 0,
            "encrypted": false,
            "bps": 0,
            "bps_rd": 0,
            "cache": {
                "no-flush": false,
                "direct": false,
                "writeback": true
            },
            "file": "/mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/incre0.qcow2"
        },
        {
            "iops_rd": 0,
            "detect_zeroes": "off",
            "image": {
                "virtual-size": 240451584,
                "filename": "/mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/incre0.qcow2",
                "format": "file",
                "actual-size": 241340416,
                "dirty-flag": false
            },
            "iops_wr": 0,
            "ro": false,
            "node-name": "#block412",
            "backing_file_depth": 0,
            "drv": "file",
            "iops": 0,
            "bps_wr": 0,
            "write_threshold": 0,
            "encrypted": false,
            "bps": 0,
            "bps_rd": 0,
            "cache": {
                "no-flush": false,
                "direct": false,
                "writeback": true
            },
            "file": "/mnt/7b12fe9c-fa0f-4f2a-82b1-3a6cd4e15ae8/temp/incre0.qcow2"
        },
        ......
    ]
}
```
Additional information: