[GFS2] Initialize extent_list earlier

Here is a patch for the latest upstream GFS2 code:
The journal extent map needs to be initialized sooner than it
currently is.  Otherwise failed mount attempts (e.g. not enough
journals, etc.) may panic trying to access the uninitialized list.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/ops_fstype.c

@@ -329,7 +329,6 @@ static int map_journal_extents(struct gfs2_sbd *sdp)
 	struct buffer_head bh;
 	int rc = 0;
 
-	INIT_LIST_HEAD(&jd->extent_list);
 	prev_db = 0;
 
 	for (lb = 0; lb < ip->i_di.di_size >> sdp->sd_sb.sb_bsize_shift; lb++) {

fs/gfs2/super.c

@@ -387,6 +387,7 @@ int gfs2_jindex_hold(struct gfs2_sbd *sdp, struct gfs2_holder *ji_gh)
 		if (!jd)
 			break;
 
+		INIT_LIST_HEAD(&jd->extent_list);
 		jd->jd_inode = gfs2_lookupi(sdp->sd_jindex, &name, 1, NULL);
 		if (!jd->jd_inode || IS_ERR(jd->jd_inode)) {
 			if (!jd->jd_inode)