Public bug reported: On Trusty and Utopic, this works:
$ sudo modprobe nbd $ sudo qemu-nbd --snapshot -c /dev/nbd0 my.qcow2 $ sudo mount /dev/nbd0p1 /mnt $ sudo umount /mnt But on Vivid, even though the mount command exists with 0, something goes awry and the mount point gets unmounted immediately. No files will actually be available, and umount will exit with 32 (umount: /mnt: not mounted). Possibly useful bits from dmesg: [ 172.010766] kvm [2750]: vcpu0 disabled perfctr wrmsr: 0xc1 data 0xffff [ 208.379278] nbd0: p1 p2 < p5 > [ 208.395989] EXT4-fs (nbd0p1): mounted filesystem with ordered data mode. Opts: (null) [ 532.601057] block nbd0: NBD_DISCONNECT [ 532.601150] block nbd0: Receive control failed (result -32) [ 532.601177] block nbd0: queue cleared [ 671.892460] nbd0: p1 p2 < p5 > [ 697.575545] EXT4-fs (nbd0p1): mounted filesystem with ordered data mode. Opts: (null) [ 775.331402] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null) [ 793.632005] EXT4-fs (nbd0p1): mounted filesystem with ordered data mode. Opts: (null) ProblemType: Bug DistroRelease: Ubuntu 15.04 Package: qemu-utils 1:2.2+dfsg-5expubuntu8 ProcVersionSignature: Ubuntu 3.19.0-9.9-generic 3.19.1 Uname: Linux 3.19.0-9-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.16.2-0ubuntu4 Architecture: amd64 CurrentDesktop: Unity Date: Mon Mar 23 10:45:24 2015 KvmCmdLine: COMMAND STAT EUID RUID PID PPID %CPU COMMAND kvm-irqfd-clean S< 0 0 486 2 0.0 [kvm-irqfd-clean] qemu-nbd Ssl 0 0 3105 1618 0.0 qemu-nbd --snapshot -c /dev/nbd0 -t /home/tribble/vivid-server-amd64.qcow2 MachineType: Notebook P750ZM ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-9-generic root=UUID=db0af986-9e96-441e-a383-e5b3ba2e837b ro quiet splash SourcePackage: qemu UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev' UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 02/25/2015 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 1.03.09aRSCC dmi.board.asset.tag: Tag 12345 dmi.board.name: P750ZM dmi.board.vendor: Notebook dmi.board.version: Not Applicable dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 9 dmi.chassis.vendor: Notebook dmi.chassis.version: N/A dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.03.09aRSCC:bd02/25/2015:svnNotebook:pnP750ZM:pvrNotApplicable:rvnNotebook:rnP750ZM:rvrNotApplicable:cvnNotebook:ct9:cvrN/A: dmi.product.name: P750ZM dmi.product.version: Not Applicable dmi.sys.vendor: Notebook ** Affects: qemu (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug vivid ** Description changed: On Trusty and Utopic, this works: $ sudo modprobe nbd $ sudo qemu-nbd --snapshot -c /dev/nbd0 my.qcow2 $ sudo mount /dev/nbd0p1 /mnt $ sudo umount /mnt But on Vivid, even though the mount command exists with 0, something goes awry and the mount point gets unmounted immediately. No files will actually be available, and umount will exit with 32 (umount: /mnt: not mounted). - Possibly use bits from dmesg: + Possibly useful bits from dmesg: [ 172.010766] kvm [2750]: vcpu0 disabled perfctr wrmsr: 0xc1 data 0xffff [ 208.379278] nbd0: p1 p2 < p5 > [ 208.395989] EXT4-fs (nbd0p1): mounted filesystem with ordered data mode. Opts: (null) [ 532.601057] block nbd0: NBD_DISCONNECT [ 532.601150] block nbd0: Receive control failed (result -32) [ 532.601177] block nbd0: queue cleared [ 671.892460] nbd0: p1 p2 < p5 > [ 697.575545] EXT4-fs (nbd0p1): mounted filesystem with ordered data mode. Opts: (null) [ 775.331402] EXT4-fs (sda2): mounted filesystem with ordered data mode. Opts: (null) [ 793.632005] EXT4-fs (nbd0p1): mounted filesystem with ordered data mode. Opts: (null) ProblemType: Bug DistroRelease: Ubuntu 15.04 Package: qemu-utils 1:2.2+dfsg-5expubuntu8 ProcVersionSignature: Ubuntu 3.19.0-9.9-generic 3.19.1 Uname: Linux 3.19.0-9-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.16.2-0ubuntu4 Architecture: amd64 CurrentDesktop: Unity Date: Mon Mar 23 10:45:24 2015 KvmCmdLine: - COMMAND STAT EUID RUID PID PPID %CPU COMMAND - kvm-irqfd-clean S< 0 0 486 2 0.0 [kvm-irqfd-clean] - qemu-nbd Ssl 0 0 3105 1618 0.0 qemu-nbd --snapshot -c /dev/nbd0 -t /home/tribble/vivid-server-amd64.qcow2 + COMMAND STAT EUID RUID PID PPID %CPU COMMAND + kvm-irqfd-clean S< 0 0 486 2 0.0 [kvm-irqfd-clean] + qemu-nbd Ssl 0 0 3105 1618 0.0 qemu-nbd --snapshot -c /dev/nbd0 -t /home/tribble/vivid-server-amd64.qcow2 MachineType: Notebook P750ZM ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-9-generic root=UUID=db0af986-9e96-441e-a383-e5b3ba2e837b ro quiet splash SourcePackage: qemu UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev' UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 02/25/2015 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 1.03.09aRSCC dmi.board.asset.tag: Tag 12345 dmi.board.name: P750ZM dmi.board.vendor: Notebook dmi.board.version: Not Applicable dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 9 dmi.chassis.vendor: Notebook dmi.chassis.version: N/A dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.03.09aRSCC:bd02/25/2015:svnNotebook:pnP750ZM:pvrNotApplicable:rvnNotebook:rnP750ZM:rvrNotApplicable:cvnNotebook:ct9:cvrN/A: dmi.product.name: P750ZM dmi.product.version: Not Applicable dmi.sys.vendor: Notebook -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1435428 Title: vivid: mounting with qemu-nbd fails To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1435428/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs