IJ25665: MMAP GIVES WRONG SIZE IF THE MMAP RANGE IS BEYOND THE END OF FIL

APAR status

• Closed as program error.

Error description

• After upgraded to v5.0.4.4 the file size is expanded to
  4k while it should be 2k. It turned out mmap gives wrong
  size if the mmap range is beyond the end of file.
  

Local fix

Problem summary

• Problem description: mmap may expand the file size to a page
  boundary if the file is a sparse file and the file size is not a
   multiple of page size.
  

Problem conclusion

• * Work around: None
  * Problem trigger: At the mmap page fault time GPFS will
  allocate a disk block if it's not allocated yet. A mmap
  read/write beyond file size will cause SIGBUS. But if the file
  size is not a multiple of page size, the page covers eof is
  accessible, and a mmap write to this page should keep current
  file size.
  * Symptom: Unexpected Results/Behavior
  * Platforms affected: All
  * Functional Area affected: All
  * Customer Impact: HiPER
  

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