xfs: create helpers for rtbitmap block/wordcount computationsrefactor-rtbitmap-macros-6.7_2023-10-19

Create helper functions that compute the number of blocks or words
necessary to store the rt bitmap.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 27 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.c b/fs/xfs/libxfs/xfs_rtbitmap.c
index efa084de58c2..aefa2b0747a5 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.c
+++ b/fs/xfs/libxfs/xfs_rtbitmap.c
@@ -1135,3 +1135,30 @@ xfs_rtalloc_extent_is_free(
 	*is_free = matches;
 	return 0;
 }
+
+/*
+ * Compute the number of rtbitmap blocks needed to track the given number of rt
+ * extents.
+ */
+xfs_filblks_t
+xfs_rtbitmap_blockcount(
+	struct xfs_mount	*mp,
+	xfs_rtbxlen_t		rtextents)
+{
+	return howmany_64(rtextents, NBBY * mp->m_sb.sb_blocksize);
+}
+
+/*
+ * Compute the number of rtbitmap words needed to populate every block of a
+ * bitmap that is large enough to track the given number of rt extents.
+ */
+unsigned long long
+xfs_rtbitmap_wordcount(
+	struct xfs_mount	*mp,
+	xfs_rtbxlen_t		rtextents)
+{
+	xfs_filblks_t		blocks;
+
+	blocks = xfs_rtbitmap_blockcount(mp, rtextents);
+	return XFS_FSB_TO_B(mp, blocks) >> XFS_WORDLOG;
+}