wrote 4096/4096 bytes at offset 0 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) === Launch VM === {"execute": "nbd-server-start", "arguments": {"addr": {"data": {"path": "SOCK_DIR/PID-socket"}, "type": "unix"}}} {"return": {}} {"execute": "query-block-exports", "arguments": {}} {"return": []} === Create a read-only NBD export === {"execute": "block-export-add", "arguments": {"id": "export0", "node-name": "fmt", "type": "nbd"}} {"return": {}} {"execute": "query-block-exports", "arguments": {}} {"return": [{"id": "export0", "node-name": "fmt", "shutting-down": false, "type": "nbd"}]} exports available: 1 export: 'fmt' size: 67108864 flags: 0x58f ( readonly flush fua df multi cache ) min block: XXX opt block: XXX max block: XXX available meta contexts: 1 base:allocation === Try a few invalid things === {"execute": "block-export-add", "arguments": {"id": "#invalid", "node-name": "fmt", "type": "nbd"}} {"error": {"class": "GenericError", "desc": "Invalid block export id"}} {"execute": "block-export-add", "arguments": {"id": "export0", "node-name": "fmt", "type": "nbd"}} {"error": {"class": "GenericError", "desc": "Block export id 'export0' is already in use"}} {"execute": "block-export-add", "arguments": {"id": "export1", "node-name": "ro", "type": "nbd", "writable": true}} {"error": {"class": "GenericError", "desc": "Cannot export read-only node as writable"}} {"execute": "block-export-del", "arguments": {"id": "export1"}} {"error": {"class": "GenericError", "desc": "Export 'export1' is not found"}} {"execute": "query-block-exports", "arguments": {}} {"return": [{"id": "export0", "node-name": "fmt", "shutting-down": false, "type": "nbd"}]} === Move export to an iothread === {"execute": "device_add", "arguments": {"drive": "fmt", "driver": "scsi-hd", "id": "sda"}} {"return": {}} {"execute": "query-block-exports", "arguments": {}} {"return": [{"id": "export0", "node-name": "fmt", "shutting-down": false, "type": "nbd"}]} exports available: 1 export: 'fmt' size: 67108864 flags: 0x58f ( readonly flush fua df multi cache ) min block: XXX opt block: XXX max block: XXX available meta contexts: 1 base:allocation === Add a writable export === {"execute": "block-export-add", "arguments": {"description": "This is the writable second export", "id": "export1", "name": "export1", "node-name": "fmt", "type": "nbd", "writable": true, "writethrough": true}} {"error": {"class": "GenericError", "desc": "Conflicts with use by block device 'sda' as 'root', which does not allow 'write' on fmt"}} {"execute": "device_del", "arguments": {"id": "sda"}} {"return": {}} {"data": {"device": "sda", "path": "/machine/peripheral/sda"}, "event": "DEVICE_DELETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}} {"execute": "device_add", "arguments": {"drive": "fmt", "driver": "scsi-hd", "id": "sda", "share-rw": true}} {"return": {}} {"execute": "block-export-add", "arguments": {"description": "This is the writable second export", "id": "export1", "name": "export1", "node-name": "fmt", "type": "nbd", "writable": true, "writethrough": true}} {"return": {}} {"execute": "query-block-exports", "arguments": {}} {"return": [{"id": "export1", "node-name": "fmt", "shutting-down": false, "type": "nbd"}, {"id": "export0", "node-name": "fmt", "shutting-down": false, "type": "nbd"}]} exports available: 2 export: 'fmt' size: 67108864 flags: 0x58f ( readonly flush fua df multi cache ) min block: XXX opt block: XXX max block: XXX available meta contexts: 1 base:allocation export: 'export1' description: This is the writable second export size: 67108864 flags: 0xced ( flush fua trim zeroes df cache fast-zero ) min block: XXX opt block: XXX max block: XXX available meta contexts: 1 base:allocation === Connect qemu-io to export1, try removing exports === read 4096/4096 bytes at offset 0 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) wrote 4096/4096 bytes at offset 4096 4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) {"execute": "block-export-del", "arguments": {"id": "export1"}} {"error": {"class": "GenericError", "desc": "export 'export1' still in use"}} {"execute": "block-export-del", "arguments": {"id": "export0"}} {"return": {}} [{"data": {"id": "export0"}, "event": "BLOCK_EXPORT_DELETED", "timestamp": {"microseconds": "USECS", "seconds": "SECS"}}] {"execute": "query-block-exports", "arguments": {}} {"return": [{"id": "export1", "node-name": "fmt", "shutting-down": false, "type": "nbd"}]} exports available: 1 export: 'export1' description: This is the writable second export size: 67108864 flags: 0xced ( flush fua trim zeroes df cache fast-zero ) min block: XXX opt block: XXX max block: XXX available meta contexts: 1 base:allocation === Connect qemu-io again, try force removing === {"execute": "block-export-del", "arguments": {"id": "export1"}} {"error": {"class": "GenericError", "desc": "export 'export1' still in use"}} {"execute": "block-export-del", "arguments": {"id": "export1", "mode": "hard"}} {"return": {}} read failed: Input/output error {"execute": "query-block-exports", "arguments": {}} {"return": []} exports available: 0 === Shut down QEMU ===