IJ54063: STAT MAY PROVIDE INCORRECT FILE SIZE IF AN APPLICATION LIKE SMB IS ALSO PRESENT ON THE NODE THAT INVOKES GPFS_STAT_X()

APAR status

• Closed as program error.

Error description

• An application like the SMB server may invoke the gpfs_stat_x()
  call (available in libgpfs.so) to retrieve stat information for
  a file. Such call implements "statlite" semantics, meaning that
  the size information is not assured to be the latest. Other
  applications which invoke standard stat()/fstat() calls do
  expect the size information to be up to date. However, due a
  problem in the logic, after gpfs_stat_x() is invoked,
  information is cached inside the kernel, and the cache is not
  purged even when other nodes change the file size (for example
  by appending data to it). The result is that stat() invoked on
  the node may still retrieve out of date file size information as
  other nodes write into the file.
  

Local fix

Problem summary

• An application like the SMB server may invoke the gpfs_stat_x()
  call (available in libgpfs.so) to retrieve stat information for
  a file. Such call implements "statlite" semantics, meaning that
  the size information is not assured to be the latest. Other
  applications which invoke standard stat()/fstat() calls do
  expect the size information to be up to date. However, due a
  problem in the logic, after gpfs_stat_x() is invoked,
  information is cached inside the kernel, and the cache is not
  purged even when other nodes change the file size (for example
  by appending data to it). The result is that stat() invoked on
  the node may still retrieve out of date file size information as
  other nodes write into the file.
  

Problem conclusion

• This problem is fixed in 5.1.9.9
  To see all Spectrum Scale APARs and their respective
  Fix solutions refer to page: 
  https://public.dhe.ibm.com/storage/spectrumscale/spectrum_scale
  _apars.html
  
  Benefits of the solution:
  With the fix, stat()/fstat() will always retrieve the latest
  file size information, even if applications on the node invoke
  gpfs_stat_x() with statlite semantics.
  
  Work Around:
  None.
  
  Problem trigger:
  Applications on a node invoke gpfs_stat_x() (including the SMB
  server) on the same node where stat()/fstat() is called.
  
  Symptom:
  Unexpected Results/Behavior
  
  Platforms affected:
  ALL Operating System environments
  
  Functional Area affected:
  All Scale Users
  
  Customer Impact:
  High Importance
  

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

  SPEC SCALE STD

• Fixed component ID

  5737F33AP

Applicable component levels