After blockcopy with pivot, a dirty-bitmap is added, but not been removed automatically.

[ChangLimin]

Hi Peter,

Since https://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=7bfff40fdfe5410c446c1cd8ec413e00530faf7d, 
after blockcopy with pivot, a dirty-bitmap is added, but not been removed automatically.
Is that something wrong?

0. start a vm, and switch on some traces
# virsh start cirros
# virsh qemu-monitor-command cirros --hmp "trace-event handle_qmp* on"
# virsh qemu-monitor-command cirros --hmp "trace-event hbitmap* on"

1. cirros0.img is opened.
# virsh domblklist cirros
 Target   Source
------------------------------------
 vda      /vms/images1/cirros0.img

2. blockcopy and pivot to cirros1.img
# virsh blockcopy cirros vda --dest /vms/images1/cirros1.img --pivot --transient-job
Successfully pivoted

3. cirros1.img is opened
# virsh domblklist cirros
 Target   Source
------------------------------------
 vda      /vms/images1/cirros1.img

4. From qemu log, a dirty-bitmap is added @1620475221.389151

77998 at 1620475125.281656:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "human-monitor-command", "arguments": {"command-line": "trace-event qmp_job* on"}, "id": "libvirt-380"}
77998 at 1620475125.299950:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "human-monitor-command", "arguments": {"command-line": "trace-event mirror* on"}, "id": "libvirt-381"}
77998 at 1620475125.317931:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "human-monitor-command", "arguments": {"command-line": "trace-event hbitmap* on"}, "id": "libvirt-382"}
77998 at 1620475217.640133:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "query-named-block-nodes", "arguments": {"flat": true}, "id": "libvirt-383"}
77998 at 1620475217.642025:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "blockdev-add", "arguments": {"node-name": "libvirt-2-storage", "driver": "file", "filename": "/vms/images1/cirros1.img", "auto-read-only": true, "aio": "native", "cache": {"no-flush": false, "direct": true}, "discard": "unmap"}, "id": "libvirt-384"}
77998 at 1620475217.643434:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "blockdev-create", "arguments": {"job-id": "create-libvirt-2-format", "options": {"driver": "qcow2", "cluster-size": 65536, "size": 46137344, "file": "libvirt-2-storage"}}, "id": "libvirt-385"}
77998 at 1620475217.827378:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "query-jobs", "id": "libvirt-386"}
77998 at 1620475217.827980:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "job-dismiss", "arguments": {"id": "create-libvirt-2-format"}, "id": "libvirt-387"}
77998 at 1620475217.850802:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "blockdev-add", "arguments": {"backing": null, "node-name": "libvirt-2-format", "driver": "qcow2", "read-only": false, "cache": {"no-flush": false, "direct": true}, "file": "libvirt-2-storage"}, "id": "libvirt-388"}
77998 at 1620475217.853157:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "blockdev-mirror", "arguments": {"auto-finalize": true, "device": "libvirt-1-format", "auto-dismiss": false, "sync": "full", "job-id": "copy-vda-libvirt-1-format", "target": "libvirt-2-format"}, "id": "libvirt-389"}
77998 at 1620475217.871674:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "query-block-jobs", "id": "libvirt-390"}
77998 at 1620475221.387625:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "query-block-jobs", "id": "libvirt-396"}
77998 at 1620475221.389151:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "transaction", "arguments": {"actions": [{"type": "block-dirty-bitmap-add", "data": {"name": "libvirt-tmp-activewrite", "persistent": false, "node": "libvirt-2-format", "disabled": false}}]}, "id": "libvirt-397"}
77998 at 1620475221.389755:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "job-complete", "arguments": {"id": "copy-vda-libvirt-1-format"}, "id": "libvirt-398"}
77998 at 1620475221.391321:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "query-jobs", "id": "libvirt-399"}
77998 at 1620475221.391926:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "job-dismiss", "arguments": {"id": "copy-vda-libvirt-1-format"}, "id": "libvirt-400"}
77998 at 1620475221.393052:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "blockdev-del", "arguments": {"node-name": "libvirt-1-format"}, "id": "libvirt-401"}
77998 at 1620475221.393702:handle_qmp_command mon 0x55ebd4b176b0 req: {"execute": "blockdev-del", "arguments": {"node-name": "libvirt-1-storage"}, "id": "libvirt-402"}
Also there are many hbitmap_xx events.

5. I have debuged the source, in qemuBlockJobProcessEventCompletedCopyBitmaps , QEMU_CAPS_BLOCKDEV_REOPEN cap is not supported unti the latest qemu. 
    So the bitmap is not removed. Is the QEMU_CAPS_BLOCKDEV_REOPEN cap be must?

Regards,
Chang Limin
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