[Bug 1432062] Re: multipath-tools-boot: support booting without user_friendly_names on devices with spaces in identifiers

[Mauricio Faria de Oliveira]

Testing w/ pure multipath setup (non-LVM).
Boots successfully, w/ no prompts.

# mount |  grep ' / '
/dev/mapper/mpath0-part2 on / type ext4 (rw,errors=remount-ro)

# multipath -l
mpath0 (0QEMU    QEMU HARDDISK   trustyroot) dm-0 QEMU    ,QEMU HARDDISK   
size=32G features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=-1 status=active
| `- 0:0:0:0 sda 8:0  active undef running
`-+- policy='round-robin 0' prio=-1 status=enabled
  `- 0:0:1:0 sdb 8:16 active undef running

Remove multipath conf/bindings/wwids..

# rm -rf /etc/multipath*
# update-initramfs -u
# reboot

Boots successfully:

# mount | grep  ' / '
/dev/mapper/0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20trustyroot-part2 on / type ext4 (rw,errors=remount-ro)

# multipath -l
0QEMU    QEMU HARDDISK   trustyroot dm-0 QEMU    ,QEMU HARDDISK   
size=32G features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=-1 status=active
| `- 0:0:0:0 sda 8:0  active undef running
`-+- policy='round-robin 0' prio=-1 status=enabled
  `- 0:0:1:0 sdb 8:16 active undef running

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Title:
  multipath-tools-boot: support booting without user_friendly_names on
  devices with spaces in identifiers

Status in multipath-tools package in Ubuntu:
  Fix Released
Status in multipath-tools source package in Trusty:
  Fix Committed

Bug description:
  [Impact]
  If a system is not installed w/ multipath support (i.e., no disk-detect/multipath/enable=true), the /etc/multipath.conf file is not installed.
  If an user later installs multipath-tools-boot, it will enable the udev rules for multipath support.
  Those rules don't handle disk devices w/ spaces on their names/uuids/models very well..

  That's because of udev's SYMLINK command using spaces to separate
  multiple links, and the kernel sysfs/dm informing \x20 instead, which
  is not correctly interpreted by some commands, resulting in file not
  found errors, for example.

  Thus, the system fails to boot.

  [Test case]
  Requires installing on a system where there are spaces in the name of the device make/model data; for instance, on POWER8 with IPR disks, or with QEMU.
  1) Install system with multipath support ('disk-detect/multipath/enable=true').
  2) Boot the system.
  3) Edit /etc/multipath.conf, remove "user_friendly_names yes" ; replace with "user_friendly_names no", or remove /etc/multipath.conf.
  4) Update the initramfs: sudo update-initramfs -u
  5) Reboot.

  [Regression potential]
  Minimal. Systems with names in the disk make/model data would not boot without user_friendly_names enabled. This patch will allow multipath-tools to correctly handle these devices in the case where friendly names are not enabled by using the devices major/minor numbers rather that its path.

  ----

  There's no problem, however, if user_friendly_names is enabled in
  multipath.conf (which is enabled in the default multipath.conf from
  the installer, if it has multipath enabled).

  Notice it's an acceptable case to install w/out multipath support, and
  enable it later for booting.

  Disk devices w/ spaces in naming is not common over SAN/storage systems, but that happens often for conventional disks; for example:
  - IBM IPR  ( IBM     IPR-0   5DB6F40000000080 )
  - IBM VDASD ( AIX     VDASD           00c96f0700004c000000014bb8e713f0.14 )
  - QEMU HARDDISK ( QEMU QEMU HARDDISK <serial> )

  So, please, is it possible to ship the default multipath.conf (e.g.,
  from installer) w/ multipath-tools-boot?

  For users not to their systems failing to boot after installing
  multipath-tools-boot manually, after a non-multipath install.

  Related bugs:
   * bug 1371634: block devices appear twice

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