GFS2: Fix use-after-free bug on umount

There was a use-after-free with the GFS2 super block during
umount. This patch moves almost all of the umount code from
->put_super into ->kill_sb, the only bit that cannot be moved
being the glock hash clearing which has to remain as ->put_super
due to umount ordering requirements. As a result its now obvious
that the kfree is the final operation, whereas before it was
hidden in ->put_super.

Also gfs2_jindex_free is then only referenced from a single file
so thats moved and marked static too.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/super.c

@@ -33,40 +33,6 @@
 #include "trans.h"
 #include "util.h"
 
-/**
- * gfs2_jindex_free - Clear all the journal index information
- * @sdp: The GFS2 superblock
- *
- */
-
-void gfs2_jindex_free(struct gfs2_sbd *sdp)
-{
-	struct list_head list, *head;
-	struct gfs2_jdesc *jd;
-	struct gfs2_journal_extent *jext;
-
-	spin_lock(&sdp->sd_jindex_spin);
-	list_add(&list, &sdp->sd_jindex_list);
-	list_del_init(&sdp->sd_jindex_list);
-	sdp->sd_journals = 0;
-	spin_unlock(&sdp->sd_jindex_spin);
-
-	while (!list_empty(&list)) {
-		jd = list_entry(list.next, struct gfs2_jdesc, jd_list);
-		head = &jd->extent_list;
-		while (!list_empty(head)) {
-			jext = list_entry(head->next,
-					  struct gfs2_journal_extent,
-					  extent_list);
-			list_del(&jext->extent_list);
-			kfree(jext);
-		}
-		list_del(&jd->jd_list);
-		iput(jd->jd_inode);
-		kfree(jd);
-	}
-}
-
 static struct gfs2_jdesc *jdesc_find_i(struct list_head *head, unsigned int jid)
 {
 	struct gfs2_jdesc *jd;