[Bug 1283303] [NEW] ATA drive /dev/disk/by-path/ incorrect due to kernel change

[Lucas Magasweran]

Public bug reported:

Starting in Ubuntu 12.04.3 the kernel commit
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a6d6a2ddabbd32c07f6a38b659e5f3db319fa5a
changed the ATA host topology changed. This was done to match the single
host to target topology of SCSI/SAS instead of having a single host with
multiple ports.

As a result, when a drive is detected by udev the path ID is determined
and assumes a multi-port host that must be rebased. This results in
/dev/disk/by-path/ nodes that overlap. For example, the following shows
two different disks, sdb and sdc, that have the same scsi-0:0:0:0 path.

# Before inserting second disk:

ubuntu at ubuntu:~$ ls -l /dev/disk/by-path/
total 0
lrwxrwxrwx 1 root root  9 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0 -> ../../sda
lrwxrwxrwx 1 root root 10 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root  9 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0 -> ../../sdb
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part1 -> ../../sdb1
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part2 -> ../../sdb2
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part3 -> ../../sdb3
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part5 -> ../../sdb5
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part6 -> ../../sdb6

# After inserting second disk:

ubuntu at ubuntu:~$ ls -l /dev/disk/by-path/
total 0
lrwxrwxrwx 1 root root  9 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0 -> ../../sda
lrwxrwxrwx 1 root root 10 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root  9 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0 -> ../../sdc
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part1 -> ../../sdb1
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part2 -> ../../sdb2
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part3 -> ../../sdb3
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part5 -> ../../sdb5
lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part6 -> ../../sdb6


I have a fix proposed and will attach a patch. I have tested it on all 12.04 releases including 12.04.4.

** Affects: udev (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1283303

Title:
  ATA drive /dev/disk/by-path/ incorrect due to kernel change

Status in “udev” package in Ubuntu:
  New

Bug description:
  Starting in Ubuntu 12.04.3 the kernel commit
  http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=9a6d6a2ddabbd32c07f6a38b659e5f3db319fa5a
  changed the ATA host topology changed. This was done to match the
  single host to target topology of SCSI/SAS instead of having a single
  host with multiple ports.

  As a result, when a drive is detected by udev the path ID is
  determined and assumes a multi-port host that must be rebased. This
  results in /dev/disk/by-path/ nodes that overlap. For example, the
  following shows two different disks, sdb and sdc, that have the same
  scsi-0:0:0:0 path.

  # Before inserting second disk:

  ubuntu at ubuntu:~$ ls -l /dev/disk/by-path/
  total 0
  lrwxrwxrwx 1 root root  9 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0 -> ../../sda
  lrwxrwxrwx 1 root root 10 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0-part1 -> ../../sda1
  lrwxrwxrwx 1 root root  9 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0 -> ../../sdb
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part1 -> ../../sdb1
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part2 -> ../../sdb2
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part3 -> ../../sdb3
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part5 -> ../../sdb5
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part6 -> ../../sdb6

  # After inserting second disk:

  ubuntu at ubuntu:~$ ls -l /dev/disk/by-path/
  total 0
  lrwxrwxrwx 1 root root  9 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0 -> ../../sda
  lrwxrwxrwx 1 root root 10 Feb 21 15:57 pci-0000:00:1a.7-usb-0:5:1.0-scsi-0:0:0:0-part1 -> ../../sda1
  lrwxrwxrwx 1 root root  9 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0 -> ../../sdc
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part1 -> ../../sdb1
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part2 -> ../../sdb2
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part3 -> ../../sdb3
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part5 -> ../../sdb5
  lrwxrwxrwx 1 root root 10 Feb 21 23:58 pci-0000:11:02.0-scsi-0:0:0:0-part6 -> ../../sdb6

  
  I have a fix proposed and will attach a patch. I have tested it on all 12.04 releases including 12.04.4.

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