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

[Mauricio Faria de Oliveira]

Hi @mathieu-tl @smoser

Back to this one. Good news.

Scott, thanks for the pointer to the error/limitation in kpartx. 
With that fixed, I could successfully boot Ubuntu 14.04.3 on QEMU disks (w/ spaces) w/out user_friendly_names.

I'm attaching a debdiff with the patch submitted to dm-devel here.
Is it still on the window for 14.04.4?

	Boot messages:
	<...>
	[   84.995873] Adding 5492672k swap on /dev/mapper/0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20helloworld-part3. <...>
	[   85.004033] EXT4-fs (dm-3): re-mounted. Opts: errors=remount-ro
	<...>

	$ sudo multipath -l
	0QEMU    QEMU HARDDISK   helloworld dm-0 QEMU    ,QEMU HARDDISK   
	size=128G features='0' hwhandler='0' wp=rw
	`-+- policy='round-robin 0' prio=-1 status=active
	  `- 0:0:0:0 sda 8:0  active undef running

	$ mount | grep ' / '
	/dev/mapper/0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20helloworld-part2 on / type ext4 (rw,errors=remount-ro)

	$ cat /proc/swaps
	Filename                                Type            Size    Used    Priority
	/dev/mapper/0QEMU\134x20\134x20\134x20\134x20QEMU\134x20HARDDISK\134x20\134x20\134x20helloworld-part3 partition 5492672 0       -1

	$ ls -l /dev/mapper
	total 0
	brw-rw---- 1 root disk 252,   0 Jan  7 13:50 0QEMU    QEMU HARDDISK   helloworld
	brw-rw---- 1 root disk 252,   1 Jan  7 13:50 0QEMU    QEMU HARDDISK   test
	lrwxrwxrwx 1 root root        7 Jan  7 13:50 0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20helloworld -> ../dm-0
	brw-rw---- 1 root disk 252,   2 Jan  7 13:50 0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20helloworld-part1
	brw-rw---- 1 root disk 252,   3 Jan  7 13:50 0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20helloworld-part2
	brw-rw---- 1 root disk 252,   4 Jan  7 13:50 0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20helloworld-part3
	lrwxrwxrwx 1 root root        7 Jan  7 13:50 0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20test -> ../dm-1
	brw-rw---- 1 root disk 252,   5 Jan  7 13:50 0QEMU\x20\x20\x20\x20QEMU\x20HARDDISK\x20\x20\x20test-part1
	crw------- 1 root root  10, 236 Jan  7 13:50 control

Notice there are 2 devices for each wholedisk (with mangled and
unmangled names); I suspect that's some inconsistency between multipath
call to libdevmapper and udev (multipath not waiting for udev to create
the nodes, and/or creating the nodes by itself / not using udev -- udev
should use the DM NAME, which indeed is mangled). I tried but could not
find the root cause for that, but it's not a regression from this patch
(it existed previously).

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https://bugs.launchpad.net/bugs/1432062

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

Status in multipath-tools package in Ubuntu:
  Confirmed

Bug description:
  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.

  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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