[PATCH 050/119] xfs: count the blocks in a btree

[Darrick J. Wong]

Provide a helper method to count the number of blocks in a short form
btree.  The refcount and rmap btrees need to know the number of blocks
already in use to set up their per-AG block reservations during mount.

v2: Use btree_visit_blocks instead of open-coding our own traversal
routine.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/xfs/libxfs/xfs_btree.c |   22 ++++++++++++++++++++++
 fs/xfs/libxfs/xfs_btree.h |    2 ++
 2 files changed, 24 insertions(+)


diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index 4b90419..50b2c32 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -4803,3 +4803,25 @@ xfs_btree_query_range(
 	return xfs_btree_overlapped_query_range(cur, low_rec, high_rec,
 			fn, priv);
 }
+
+int
+xfs_btree_count_blocks_helper(
+	struct xfs_btree_cur	*cur,
+	int			level,
+	void			*data)
+{
+	xfs_extlen_t		*blocks = data;
+	(*blocks)++;
+
+	return 0;
+}
+
+/* Count the blocks in a btree and return the result in *blocks. */
+int
+xfs_btree_count_blocks(
+	struct xfs_btree_cur	*cur,
+	xfs_extlen_t		*blocks)
+{
+	return xfs_btree_visit_blocks(cur, xfs_btree_count_blocks_helper,
+			blocks);
+}
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 9963c48..6fa13a9 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -519,4 +519,6 @@ typedef int (*xfs_btree_visit_blocks_fn)(struct xfs_btree_cur *cur, int level,
 int xfs_btree_visit_blocks(struct xfs_btree_cur *cur,
 		xfs_btree_visit_blocks_fn fn, void *data);
 
+int xfs_btree_count_blocks(struct xfs_btree_cur *cur, xfs_extlen_t *blocks);
+
 #endif	/* __XFS_BTREE_H__ */