[Bug 1435428] [NEW] vivid: mounting with qemu-nbd fails

Mon Mar 23 16:53:59 UTC 2015

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

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Title:
  vivid: mounting with qemu-nbd fails

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