mkfs.gfs2 and gfs2_grow now reserve enough space for one more rindex entry in the rindex file, but keep the file size the same. gfs2_grow does this through the new fallocate gfs2 function call. mkfs.gfs2 can just do this by hand, since it's working directly on the block device.
Ran mkfs, filled the file system, ran growfs and filled the file system several times more and was able to grow the file system every time. Marking verified against gfs2-utils-3.0.12-40.el6.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
http://rhn.redhat.com/errata/RHBA-2011-0537.html