[Bug 1435428] Re: vivid: systemd breaks qemu-nbd mounting

[Jason Gerard DeRose]

** Summary changed:

- vivid: mounting with qemu-nbd fails
+ vivid: systemd breaks qemu-nbd mounting

** 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 exits 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).
+ 
+ However, if I reboot using the Upstart grub entry (in Advanced options
+ for Ubuntu), this works on Vivid.
+ 
+ I'm at a loss for how exactly systemd is interacting with qemu-nbd, but
+ somehow it is.
  
  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

** Tags added: systemd-boot

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https://bugs.launchpad.net/bugs/1435428

Title:
  vivid: systemd breaks qemu-nbd mounting

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