[PATCH 4/5] xfs: create a ranged query function for refcount btrees

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Implement ranged queries for refcount records.  The next patch will use
this to scan refcount data.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/libxfs/xfs_refcount.c |   41 +++++++++++++++++++++++++++++++++++++++++
 fs/xfs/libxfs/xfs_refcount.h |   10 ++++++++++
 2 files changed, 51 insertions(+)


diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
index c834078449ed..311c61b4cf8e 100644
--- a/fs/xfs/libxfs/xfs_refcount.c
+++ b/fs/xfs/libxfs/xfs_refcount.c
@@ -2029,6 +2029,47 @@ xfs_refcount_has_records(
 	return xfs_btree_has_records(cur, &low, &high, NULL, outcome);
 }
 
+struct xfs_refcount_query_range_info {
+	xfs_refcount_query_range_fn	fn;
+	void				*priv;
+};
+
+/* Format btree record and pass to our callback. */
+STATIC int
+xfs_refcount_query_range_helper(
+	struct xfs_btree_cur		*cur,
+	const union xfs_btree_rec	*rec,
+	void				*priv)
+{
+	struct xfs_refcount_query_range_info	*query = priv;
+	struct xfs_refcount_irec	irec;
+	xfs_failaddr_t			fa;
+
+	xfs_refcount_btrec_to_irec(rec, &irec);
+	fa = xfs_refcount_check_irec(cur, &irec);
+	if (fa)
+		return xfs_refcount_complain_bad_rec(cur, fa, &irec);
+
+	return query->fn(cur, &irec, query->priv);
+}
+
+/* Find all refcount records between two keys. */
+int
+xfs_refcount_query_range(
+	struct xfs_btree_cur		*cur,
+	const struct xfs_refcount_irec	*low_rec,
+	const struct xfs_refcount_irec	*high_rec,
+	xfs_refcount_query_range_fn	fn,
+	void				*priv)
+{
+	union xfs_btree_irec		low_brec = { .rc = *low_rec };
+	union xfs_btree_irec		high_brec = { .rc = *high_rec };
+	struct xfs_refcount_query_range_info query = { .priv = priv, .fn = fn };
+
+	return xfs_btree_query_range(cur, &low_brec, &high_brec,
+			xfs_refcount_query_range_helper, &query);
+}
+
 int __init
 xfs_refcount_intent_init_cache(void)
 {
diff --git a/fs/xfs/libxfs/xfs_refcount.h b/fs/xfs/libxfs/xfs_refcount.h
index 2d6fecb258bb..9563eb91be17 100644
--- a/fs/xfs/libxfs/xfs_refcount.h
+++ b/fs/xfs/libxfs/xfs_refcount.h
@@ -129,4 +129,14 @@ extern struct kmem_cache	*xfs_refcount_intent_cache;
 int __init xfs_refcount_intent_init_cache(void);
 void xfs_refcount_intent_destroy_cache(void);
 
+typedef int (*xfs_refcount_query_range_fn)(
+	struct xfs_btree_cur		*cur,
+	const struct xfs_refcount_irec	*rec,
+	void				*priv);
+
+int xfs_refcount_query_range(struct xfs_btree_cur *cur,
+		const struct xfs_refcount_irec *low_rec,
+		const struct xfs_refcount_irec *high_rec,
+		xfs_refcount_query_range_fn fn, void *priv);
+
 #endif	/* __XFS_REFCOUNT_H__ */