xfs: actually check xfs_btree_check_block return in xfs_btree_islastblock

Coverity points out that xfs_btree_islastblock doesn't check the return
value of xfs_btree_check_block.  Since the question "Does the cursor
point to the last block in this level?" only makes sense if the caller
previously performed a lookup or seek operation, the block should
already have been checked.

Therefore, check the return value in an ASSERT and turn the whole thing
into a static inline predicate.

Coverity-id: 114069
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_btree.c

@@ -716,25 +716,6 @@ xfs_btree_get_bufs(
 	return xfs_trans_get_buf(tp, mp->m_ddev_targp, d, mp->m_bsize, 0);
 }
 
-/*
- * Check for the cursor referring to the last block at the given level.
- */
-int					/* 1=is last block, 0=not last block */
-xfs_btree_islastblock(
-	xfs_btree_cur_t		*cur,	/* btree cursor */
-	int			level)	/* level to check */
-{
-	struct xfs_btree_block	*block;	/* generic btree block pointer */
-	xfs_buf_t		*bp;	/* buffer containing block */
-
-	block = xfs_btree_get_block(cur, level, &bp);
-	xfs_btree_check_block(cur, block, level, bp);
-	if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
-		return block->bb_u.l.bb_rightsib == cpu_to_be64(NULLFSBLOCK);
-	else
-		return block->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK);
-}
-
 /*
  * Change the cursor to point to the first record at the given level.
  * Other levels are unaffected.

fs/xfs/libxfs/xfs_btree.h

@@ -317,14 +317,6 @@ xfs_btree_get_bufs(
 	xfs_agnumber_t		agno,	/* allocation group number */
 	xfs_agblock_t		agbno);	/* allocation group block number */
 
-/*
- * Check for the cursor referring to the last block at the given level.
- */
-int					/* 1=is last block, 0=not last block */
-xfs_btree_islastblock(
-	xfs_btree_cur_t		*cur,	/* btree cursor */
-	int			level);	/* level to check */
-
 /*
  * Compute first and last byte offsets for the fields given.
  * Interprets the offsets table, which contains struct field offsets.
@@ -524,4 +516,21 @@ int xfs_btree_has_record(struct xfs_btree_cur *cur, union xfs_btree_irec *low,
 		union xfs_btree_irec *high, bool *exists);
 bool xfs_btree_has_more_records(struct xfs_btree_cur *cur);
 
+/* Does this cursor point to the last block in the given level? */
+static inline bool
+xfs_btree_islastblock(
+	xfs_btree_cur_t		*cur,
+	int			level)
+{
+	struct xfs_btree_block	*block;
+	struct xfs_buf		*bp;
+
+	block = xfs_btree_get_block(cur, level, &bp);
+	ASSERT(block && xfs_btree_check_block(cur, block, level, bp) == 0);
+
+	if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
+		return block->bb_u.l.bb_rightsib == cpu_to_be64(NULLFSBLOCK);
+	return block->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK);
+}
+
 #endif	/* __XFS_BTREE_H__ */