xfs: fix gcc 4.6 set but not read and unused statement warnings

[hch: dropped a few hunks that need structural changes instead]

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index 6fe5c02..af168fa 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -683,8 +683,6 @@
 	xfs_agblock_t	ltbno;		/* start bno of left side entry */
 	xfs_agblock_t	ltbnoa;		/* aligned ... */
 	xfs_extlen_t	ltdiff;		/* difference to left side entry */
-	/*REFERENCED*/
-	xfs_agblock_t	ltend;		/* end bno of left side entry */
 	xfs_extlen_t	ltlen;		/* length of left side entry */
 	xfs_extlen_t	ltlena;		/* aligned ... */
 	xfs_agblock_t	ltnew;		/* useful start bno of left side */
@@ -809,8 +807,7 @@
 		if ((error = xfs_alloc_get_rec(cnt_cur, &ltbno, &ltlen, &i)))
 			goto error0;
 		XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
-		ltend = ltbno + ltlen;
-		ASSERT(ltend <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
+		ASSERT(ltbno + ltlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
 		args->len = blen;
 		if (!xfs_alloc_fix_minleft(args)) {
 			xfs_btree_del_cursor(cnt_cur, XFS_BTREE_NOERROR);
@@ -823,7 +820,7 @@
 		 */
 		args->agbno = bnew;
 		ASSERT(bnew >= ltbno);
-		ASSERT(bnew + blen <= ltend);
+		ASSERT(bnew + blen <= ltbno + ltlen);
 		/*
 		 * Set up a cursor for the by-bno tree.
 		 */
@@ -1152,7 +1149,6 @@
 	/*
 	 * Fix up the length and compute the useful address.
 	 */
-	ltend = ltbno + ltlen;
 	args->len = XFS_EXTLEN_MIN(ltlena, args->maxlen);
 	xfs_alloc_fix_len(args);
 	if (!xfs_alloc_fix_minleft(args)) {
@@ -1165,7 +1161,7 @@
 	(void)xfs_alloc_compute_diff(args->agbno, rlen, args->alignment, ltbno,
 		ltlen, &ltnew);
 	ASSERT(ltnew >= ltbno);
-	ASSERT(ltnew + rlen <= ltend);
+	ASSERT(ltnew + rlen <= ltbno + ltlen);
 	ASSERT(ltnew + rlen <= be32_to_cpu(XFS_BUF_TO_AGF(args->agbp)->agf_length));
 	args->agbno = ltnew;
 	if ((error = xfs_alloc_fixup_trees(cnt_cur, bno_cur_lt, ltbno, ltlen,