GFS2: panics on quotacheck update

Handle block allocation for forceful unstuffing of quota dinode during quota
update using quotactl(). Also fix block reservation for special cases when
quotas cross over block boundaries and update 2 blocks instead of 1.
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/quota.c

@@ -1587,6 +1587,8 @@ static int gfs2_set_dqblk(struct super_block *sb, int type, qid_t id,
 
 	offset = qd2offset(qd);
 	alloc_required = gfs2_write_alloc_required(ip, offset, sizeof(struct gfs2_quota));
+	if (gfs2_is_stuffed(ip))
+		alloc_required = 1;
 	if (alloc_required) {
 		al = gfs2_alloc_get(ip);
 		if (al == NULL)
@@ -1600,7 +1602,9 @@ static int gfs2_set_dqblk(struct super_block *sb, int type, qid_t id,
 		blocks += gfs2_rg_blocks(al);
 	}
 
-	error = gfs2_trans_begin(sdp, blocks + RES_DINODE + 1, 0);
+	/* Some quotas span block boundaries and can update two blocks,
+	   adding an extra block to the transaction to handle such quotas */
+	error = gfs2_trans_begin(sdp, blocks + RES_DINODE + 2, 0);
 	if (error)
 		goto out_release;