2GB to 4GB-1 by using long instead of size_t for the sm size.
* it is done to prevent user from running into the ftruncate() in
common sm component (and possibly others) problem that ftruncate
takes an off_t which is a signed long integer. If we use an
unsigned long, it'll run into an invalid argument errno=22.
* See trac #1117
This commit was SVN r15752.
010d216db9