xfs: create helpers to deal with rounding xfs_filblks_t to rtx boundaries

We're about to segment xfs_rtblock_t addresses, so we must create
type-specific helpers to do rt extent rounding of file mapping block
lengths because the rtb helpers soon will not do the right thing there.

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

Author: Darrick J. Wong

fs/xfs/libxfs/xfs_rtbitmap.c

@@ -1123,7 +1123,7 @@ xfs_rtfree_blocks(
 
 	ASSERT(rtlen <= XFS_MAX_BMBT_EXTLEN);
 
-	mod = xfs_rtb_to_rtxoff(mp, rtlen);
+	mod = xfs_blen_to_rtxoff(mp, rtlen);
 	if (mod) {
 		ASSERT(mod == 0);
 		return -EIO;

fs/xfs/libxfs/xfs_rtbitmap.h

@@ -101,6 +101,27 @@ xfs_blen_to_rtbxlen(
 	return div_u64(blen, mp->m_sb.sb_rextsize);
 }
 
+/* Return the offset of a file block length within an rt extent. */
+static inline xfs_extlen_t
+xfs_blen_to_rtxoff(
+	struct xfs_mount	*mp,
+	xfs_filblks_t		blen)
+{
+	if (likely(mp->m_rtxblklog >= 0))
+		return blen & mp->m_rtxblkmask;
+
+	return do_div(blen, mp->m_sb.sb_rextsize);
+}
+
+/* Round this block count up to the nearest rt extent size. */
+static inline xfs_filblks_t
+xfs_blen_roundup_rtx(
+	struct xfs_mount	*mp,
+	xfs_filblks_t		blen)
+{
+	return roundup_64(blen, mp->m_sb.sb_rextsize);
+}
+
 /* Convert an rt block number into an rt extent number. */
 static inline xfs_rtxnum_t
 xfs_rtb_to_rtx(
@@ -126,15 +147,6 @@ xfs_rtb_to_rtxoff(
 	return do_div(rtbno, mp->m_sb.sb_rextsize);
 }
 
-/* Round this rtblock up to the nearest rt extent size. */
-static inline xfs_rtblock_t
-xfs_rtb_roundup_rtx(
-	struct xfs_mount	*mp,
-	xfs_rtblock_t		rtbno)
-{
-	return roundup_64(rtbno, mp->m_sb.sb_rextsize);
-}
-
 /* Round this file block offset up to the nearest rt extent size. */
 static inline xfs_rtblock_t
 xfs_fileoff_roundup_rtx(

fs/xfs/xfs_exchrange.c

@@ -217,7 +217,7 @@ xfs_exchrange_mappings(
 	 * length in @fxr are safe to round up.
 	 */
 	if (xfs_inode_has_bigrtalloc(ip2))
-		req.blockcount = xfs_rtb_roundup_rtx(mp, req.blockcount);
+		req.blockcount = xfs_blen_roundup_rtx(mp, req.blockcount);
 
 	error = xfs_exchrange_estimate(&req);
 	if (error)