In order to grow a gfs2 filesystem, gfs2 needs to add additional resource groups to manage the new space. gfs2_grow does this by writing to the rindex file. If there are no free blocks available in the filesystem at its current size, and the last block of the rindex file is too full to add another resource group entry, gfs2_grow will be unable to write out the necessary information for gfs2 to be able to use the new space. When this happens, gfs2_grow is unable to grow the filesystem.
This problem can only happen on filesytems where the last block of the rindex file is too full to add another resource group entry. Whether or not this is the case is based on the filesystem size, the blocksize, and the resource group size.
If this problem occurs, gfs2_grow will report "Error writing new rindex entries;aborted." In this case, the user must remove or truncate a file to free up spacce for gfs2_grow to complete. Once the filesystem has been grown, the file can safely be added back to the gfs2 filesystem.