xfs: create a helper to compute leftovers of realtime extents

Create a helper to compute the misalignment between a file extent
(xfs_extlen_t) and a realtime extent.

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

1 files changed, 9 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_rtbitmap.h b/fs/xfs/libxfs/xfs_rtbitmap.h
index 099ea8902aaa..b6a4c46bddc0 100644
--- a/fs/xfs/libxfs/xfs_rtbitmap.h
+++ b/fs/xfs/libxfs/xfs_rtbitmap.h
@@ -22,6 +22,15 @@ xfs_rtxlen_to_extlen(
 	return rtxlen * mp->m_sb.sb_rextsize;
 }
 
+/* Compute the misalignment between an extent length and a realtime extent .*/
+static inline unsigned int
+xfs_extlen_to_rtxmod(
+	struct xfs_mount	*mp,
+	xfs_extlen_t		len)
+{
+	return len % mp->m_sb.sb_rextsize;
+}
+
 /*
  * Functions for walking free space rtextents in the realtime bitmap.
  */