xfs: add scrub cross-referencing helpers for the free space btrees

Add a couple of functions to the free space btrees that will be used
to cross-reference metadata against the bnobt/cntbt, and a generic
btree function that provides the real implementation.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/libxfs/xfs_alloc.c

@@ -167,7 +167,7 @@ xfs_alloc_lookup_ge(
  * Lookup the first record less than or equal to [bno, len]
  * in the btree given by cur.
  */
-static int				/* error */
+int					/* error */
 xfs_alloc_lookup_le(
 	struct xfs_btree_cur	*cur,	/* btree cursor */
 	xfs_agblock_t		bno,	/* starting block of extent */
@@ -2996,3 +2996,22 @@ xfs_verify_fsbno(
 		return false;
 	return xfs_verify_agbno(mp, agno, XFS_FSB_TO_AGBNO(mp, fsbno));
 }
+
+/* Is there a record covering a given extent? */
+int
+xfs_alloc_has_record(
+	struct xfs_btree_cur	*cur,
+	xfs_agblock_t		bno,
+	xfs_extlen_t		len,
+	bool			*exists)
+{
+	union xfs_btree_irec	low;
+	union xfs_btree_irec	high;
+
+	memset(&low, 0, sizeof(low));
+	low.a.ar_startblock = bno;
+	memset(&high, 0xFF, sizeof(high));
+	high.a.ar_startblock = bno + len - 1;
+
+	return xfs_btree_has_record(cur, &low, &high, exists);
+}

fs/xfs/libxfs/xfs_alloc.h

@@ -197,6 +197,13 @@ xfs_free_extent(
 	struct xfs_owner_info	*oinfo,	/* extent owner */
 	enum xfs_ag_resv_type	type);	/* block reservation type */
 
+int				/* error */
+xfs_alloc_lookup_le(
+	struct xfs_btree_cur	*cur,	/* btree cursor */
+	xfs_agblock_t		bno,	/* starting block of extent */
+	xfs_extlen_t		len,	/* length of extent */
+	int			*stat);	/* success/failure */
+
 int				/* error */
 xfs_alloc_lookup_ge(
 	struct xfs_btree_cur	*cur,	/* btree cursor */
@@ -237,4 +244,7 @@ bool xfs_verify_agbno(struct xfs_mount *mp, xfs_agnumber_t agno,
 		xfs_agblock_t agbno);
 bool xfs_verify_fsbno(struct xfs_mount *mp, xfs_fsblock_t fsbno);
 
+int xfs_alloc_has_record(struct xfs_btree_cur *cur, xfs_agblock_t bno,
+		xfs_extlen_t len, bool *exist);
+
 #endif	/* __XFS_ALLOC_H__ */

fs/xfs/libxfs/xfs_btree.c

@@ -4998,3 +4998,33 @@ xfs_btree_diff_two_ptrs(
 		return (int64_t)be64_to_cpu(a->l) - be64_to_cpu(b->l);
 	return (int64_t)be32_to_cpu(a->s) - be32_to_cpu(b->s);
 }
+
+/* If there's an extent, we're done. */
+STATIC int
+xfs_btree_has_record_helper(
+	struct xfs_btree_cur		*cur,
+	union xfs_btree_rec		*rec,
+	void				*priv)
+{
+	return XFS_BTREE_QUERY_RANGE_ABORT;
+}
+
+/* Is there a record covering a given range of keys? */
+int
+xfs_btree_has_record(
+	struct xfs_btree_cur	*cur,
+	union xfs_btree_irec	*low,
+	union xfs_btree_irec	*high,
+	bool			*exists)
+{
+	int			error;
+
+	error = xfs_btree_query_range(cur, low, high,
+			&xfs_btree_has_record_helper, NULL);
+	if (error == XFS_BTREE_QUERY_RANGE_ABORT) {
+		*exists = true;
+		return 0;
+	}
+	*exists = false;
+	return error;
+}

fs/xfs/libxfs/xfs_btree.h

@@ -547,5 +547,7 @@ void xfs_btree_get_keys(struct xfs_btree_cur *cur,
 		struct xfs_btree_block *block, union xfs_btree_key *key);
 union xfs_btree_key *xfs_btree_high_key_from_key(struct xfs_btree_cur *cur,
 		union xfs_btree_key *key);
+int xfs_btree_has_record(struct xfs_btree_cur *cur, union xfs_btree_irec *low,
+		union xfs_btree_irec *high, bool *exists);
 
 #endif	/* __XFS_BTREE_H__ */