xfs: replace do_mod with native operations

do_mod() is a hold-over from when we have different sizes for file
offsets and and other internal values for 40 bit XFS filesystems.
Hence depending on build flags variables passed to do_mod() could
change size. We no longer support those small format filesystems and
hence everything is of fixed size theses days, even on 32 bit
platforms.

As such, we can convert all the do_mod() callers to platform
optimised modulus operations as defined by linux/math64.h.
Individual conversions depend on the types of variables being used.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 23 insertions, 14 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 6a79a07528cf..01628f0c9a0c 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -2923,7 +2923,7 @@ xfs_bmap_extsize_align(
 	 * perform this alignment, or if a truncate shot us in the
 	 * foot.
 	 */
-	temp = do_mod(orig_off, extsz);
+	div_u64_rem(orig_off, extsz, &temp);
 	if (temp) {
 		align_alen += temp;
 		align_off -= temp;
@@ -3497,15 +3497,17 @@ xfs_bmap_btalloc(
 	/* apply extent size hints if obtained earlier */
 	if (align) {
 		args.prod = align;
-		if ((args.mod = (xfs_extlen_t)do_mod(ap->offset, args.prod)))
-			args.mod = (xfs_extlen_t)(args.prod - args.mod);
+		div_u64_rem(ap->offset, args.prod, &args.mod);
+		if (args.mod)
+			args.mod = args.prod - args.mod;
 	} else if (mp->m_sb.sb_blocksize >= PAGE_SIZE) {
 		args.prod = 1;
 		args.mod = 0;
 	} else {
 		args.prod = PAGE_SIZE >> mp->m_sb.sb_blocklog;
-		if ((args.mod = (xfs_extlen_t)(do_mod(ap->offset, args.prod))))
-			args.mod = (xfs_extlen_t)(args.prod - args.mod);
+		div_u64_rem(ap->offset, args.prod, &args.mod);
+		if (args.mod)
+			args.mod = args.prod - args.mod;
 	}
 	/*
 	 * If we are not low on available data blocks, and the
@@ -4953,13 +4955,15 @@ xfs_bmap_del_extent_real(
 	if (whichfork == XFS_DATA_FORK && XFS_IS_REALTIME_INODE(ip)) {
 		xfs_fsblock_t	bno;
 		xfs_filblks_t	len;
+		xfs_extlen_t	mod;
+
+		bno = div_u64_rem(del->br_startblock, mp->m_sb.sb_rextsize,
+				  &mod);
+		ASSERT(mod == 0);
+		len = div_u64_rem(del->br_blockcount, mp->m_sb.sb_rextsize,
+				  &mod);
+		ASSERT(mod == 0);
 
-		ASSERT(do_mod(del->br_blockcount, mp->m_sb.sb_rextsize) == 0);
-		ASSERT(do_mod(del->br_startblock, mp->m_sb.sb_rextsize) == 0);
-		bno = del->br_startblock;
-		len = del->br_blockcount;
-		do_div(bno, mp->m_sb.sb_rextsize);
-		do_div(len, mp->m_sb.sb_rextsize);
 		error = xfs_rtfree_extent(tp, bno, (xfs_extlen_t)len);
 		if (error)
 			goto done;
@@ -5296,9 +5300,12 @@ __xfs_bunmapi(
 			del.br_blockcount = max_len;
 		}
 
+		if (!isrt)
+			goto delete;
+
 		sum = del.br_startblock + del.br_blockcount;
-		if (isrt &&
-		    (mod = do_mod(sum, mp->m_sb.sb_rextsize))) {
+		div_u64_rem(sum, mp->m_sb.sb_rextsize, &mod);
+		if (mod) {
 			/*
 			 * Realtime extent not lined up at the end.
 			 * The extent could have been split into written
@@ -5345,7 +5352,8 @@ __xfs_bunmapi(
 				goto error0;
 			goto nodelete;
 		}
-		if (isrt && (mod = do_mod(del.br_startblock, mp->m_sb.sb_rextsize))) {
+		div_u64_rem(del.br_startblock, mp->m_sb.sb_rextsize, &mod);
+		if (mod) {
 			/*
 			 * Realtime extent is lined up at the end but not
 			 * at the front.  We'll get rid of full extents if
@@ -5414,6 +5422,7 @@ __xfs_bunmapi(
 			}
 		}
 
+delete:
 		if (wasdel) {
 			error = xfs_bmap_del_extent_delay(ip, whichfork, &icur,
 					&got, &del);