PM49260: PM12195 CAUSES A DEADLOCK ON /ETC/MTAB IF THE VOB IS NFS STORED AND THE UNDERLYING NFS STORAGE IS NOT YET MOUNTED

Rational ClearCase Fix Pack (7.1.2.5) for version 7.1.2
Rational ClearCase Fix Pack (8.0.0.1) for version 8.0
Rational ClearCase Fix Pack 14 (7.1.2.14) for 7.1.2
Rational ClearCase Fix Pack 11 (8.0.0.11) for 8.0
Rational ClearCase Fix Pack 12 (8.0.0.12) for 8.0
Rational ClearCase Fix Pack 15 (7.1.2.15) for 7.1.2
Rational ClearCase Fix Pack 13 (8.0.0.13) for 8.0
Rational ClearCase Fix Pack 16 (7.1.2.16) for 7.1.2
Rational ClearCase Fix Pack 17 (7.1.2.17) for 7.1.2
Rational ClearCase Fix Pack 14 (8.0.0.14) for 8.0
Rational ClearCase Fix Pack 18 (7.1.2.18) for 7.1.2
Rational ClearCase Fix Pack 15 (8.0.0.15) for 8.0
Rational ClearCase Fix Pack 19 (7.1.2.19) for 7.1.2
Rational ClearCase Fix Pack 16 (8.0.0.16) for 8.0
Rational ClearCase Fix Pack 17 (8.0.0.17) for 8.0
Rational ClearCase Fix Pack 18 (8.0.0.18) for 8.0
Rational ClearCase Fix Pack 19 (8.0.0.19) for 8.0
Rational ClearCase Fix Pack 20 (8.0.0.20) for 8.0
Rational ClearCase Fix Pack 21 (8.0.0.21) for 8.0

APAR status

• Closed as program error.

Error description

• PM12195 causes a deadlock on /etc/mtab if the VOB is NFS stored
  and the underlying NFS storage is not yet mounted
  
  
  
  ClearCase 7.1.2.4
  
  
  
  RedHat 4 Update 8 (deadlock)
  RedHat 5 or SuSE 10 SP3 (10 second delay for each VOB)
  
  
  Description of Problem:
  
    1)  A 'cleartool mount' command will generate an RPC call to
  the mntrpc_server, and the mntrpc_server forks mount.mvfs
    2)  mount.mvfs obtains a file lock on /etc/mtab to prevent
  corruption of the mtab file
    3)  mount.mvfs then proceeds to try and mount the VOB.  It
  traverses the VOB storage path which, if not already mounted,
  triggers an automount of the NFS storage
    4)  Automount eventually calls /bin/mount to do the mount.
  Mount then attempts to take a lock on /etc/mtab and finds it
  locked and so waits
    5)  mount.mvfs is waiting on mount to finish mounting the NFS
  storage and now the Automount mount is waiting on a lock held by
  mount.mvfs to be freed to allow the VOB storage to me mounted
  
  On RedHat 5.3 and SuSE 10.3 the attempt to take the lock by
  mount times out after 10 seconds and fails, leading to a 10
  second delay per VOB to be mounted at boot. On RedHat 4.8, the
  timeout never occurs and the system hangs indefinitely.
  
  
  Workaround:  none
  

Local fix

Problem summary

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  * USERS AFFECTED:                                              *
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  * PROBLEM DESCRIPTION:                                         *
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  The problem was a locking conflict between the MVFS mount
  and the automounter, in the particular case where the VOB
  storage had become unmounted after a time interval, and
  needed to be re-mounted by the automounter.
  

Problem conclusion

• This problem is fixed in ClearCase 7.1.1.8, 7.1.2.5, and
  8.0.0.1.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  CLEARCASE UNIX

• Fixed component ID

  5724G2901

Applicable component levels

• R712 PSN

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