[Bug 1334699] [NEW] mountroot_fail returns success when it has not changed the root found situation

[Paul FitzPatrick]

Public bug reported:


When booting and the root filesystem is not found, initramfs runs any mountroot_fail hook scripts which have been registered. The mdadm mountroot_fail script tries to assemble arrays and if "mdadm  --incremental --run --scan" or "mdadm --assemble --scan --run" return successfully it returns with a 0 return value. This will cause the top level caller to exit any other failure hooks and try to mount root again. 

This seems good, but the mdadm executions will also return successfully
if they made no change to the situation. In my particular problem, the
kernel did not have access to the modules needed to see my hard drives.
Thus mdadm could not assemble them into the root device. However, since
the mountroot_fail function returned success (since mdadm had no
failures in assembling no devices) the initramfs continued to loop
forever trying to find root, running mountroot_fail in mdadm-functions,
repeat. It would never drop to am emergency shell so I could examine the
situation.

I did not discover my module issue until I added a check in the
mountroot_fail to see if the script had been run more than once. Below
is my code which I added before each "return 0" in the original script,
but it is not suitable as a real solution.

if [ -f /tmp/mdadm_loop ] ; then
  return 1
fi
touch /tmp/mdadm_loop
return 0


Below is required info based on reporting instructions.

# lsb_release -rd
Description:    Ubuntu 14.04 LTS
Release:        14.04

# apt-cache policy mdadm
mdadm:
  Installed: 3.2.5-5ubuntu4.1
  Candidate: 3.2.5-5ubuntu4.1
  Version table:
 *** 3.2.5-5ubuntu4.1 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.2.5-5ubuntu4 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

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

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https://bugs.launchpad.net/bugs/1334699

Title:
  mountroot_fail returns success when it has not changed the root found
  situation

Status in “mdadm” package in Ubuntu:
  New

Bug description:
  
  When booting and the root filesystem is not found, initramfs runs any mountroot_fail hook scripts which have been registered. The mdadm mountroot_fail script tries to assemble arrays and if "mdadm  --incremental --run --scan" or "mdadm --assemble --scan --run" return successfully it returns with a 0 return value. This will cause the top level caller to exit any other failure hooks and try to mount root again. 

  This seems good, but the mdadm executions will also return
  successfully if they made no change to the situation. In my particular
  problem, the kernel did not have access to the modules needed to see
  my hard drives. Thus mdadm could not assemble them into the root
  device. However, since the mountroot_fail function returned success
  (since mdadm had no failures in assembling no devices) the initramfs
  continued to loop forever trying to find root, running mountroot_fail
  in mdadm-functions, repeat. It would never drop to am emergency shell
  so I could examine the situation.

  I did not discover my module issue until I added a check in the
  mountroot_fail to see if the script had been run more than once. Below
  is my code which I added before each "return 0" in the original
  script, but it is not suitable as a real solution.

  if [ -f /tmp/mdadm_loop ] ; then
    return 1
  fi
  touch /tmp/mdadm_loop
  return 0

  
  Below is required info based on reporting instructions.

  # lsb_release -rd
  Description:    Ubuntu 14.04 LTS
  Release:        14.04

  # apt-cache policy mdadm
  mdadm:
    Installed: 3.2.5-5ubuntu4.1
    Candidate: 3.2.5-5ubuntu4.1
    Version table:
   *** 3.2.5-5ubuntu4.1 0
          500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
          100 /var/lib/dpkg/status
       3.2.5-5ubuntu4 0
          500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

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