fix file_system_type leak on gfs2meta mount
 

On Thu, Apr 17, 2008 at 09:39:12AM +0100, swhiteho@redhat.com wrote:
> From: Christoph Hellwig <hch@lst.de>
>
> get_gfs2_sb does a get_fs_type without doing a put_filesystem and
> thus leaking a file_system_type reference everytime it's called.
>
> Just use gfs2_fs_type directly instead of doing the lookup and thus
> fix the problem.

Btw, after this patch we should remove the get_fs_type export. It's
not used by modules and because put_filesystem is not exported every
modular user would fundamentally have the same leak as the one fixed in
this patch.