Request for Review: 7007769: VM crashes with SIGBUS writing PerfData if tmp space is full

[Bob Vandette]

New changeset for review.

http://cr.openjdk.java.net/~bobv/7007769

If there is very little /tmp space, the VM will be able to successfully mmap the 
performance data area in /tmp but when the VM attempts to access this memory 
region, it will crash with a SIGBUS if there is insufficient disk space in /tmp.

Solaris will fail the ftruncate call we use to extend the newly created file but Linux does not.
To work around this problem, I write a single byte to each page of the file about to be mmap'd
top reserve the space on the disk.

Bob Vandette
Oracle