v4.19.13 snapshot.
diff --git a/fs/xfs/libxfs/xfs_bit.h b/fs/xfs/libxfs/xfs_bit.h
new file mode 100644
index 0000000..99017b8
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_bit.h
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000,2002,2005 Silicon Graphics, Inc.
+ * All Rights Reserved.
+ */
+#ifndef __XFS_BIT_H__
+#define __XFS_BIT_H__
+
+/*
+ * XFS bit manipulation routines.
+ */
+
+/*
+ * masks with n high/low bits set, 64-bit values
+ */
+static inline uint64_t xfs_mask64hi(int n)
+{
+ return (uint64_t)-1 << (64 - (n));
+}
+static inline uint32_t xfs_mask32lo(int n)
+{
+ return ((uint32_t)1 << (n)) - 1;
+}
+static inline uint64_t xfs_mask64lo(int n)
+{
+ return ((uint64_t)1 << (n)) - 1;
+}
+
+/* Get high bit set out of 32-bit argument, -1 if none set */
+static inline int xfs_highbit32(uint32_t v)
+{
+ return fls(v) - 1;
+}
+
+/* Get high bit set out of 64-bit argument, -1 if none set */
+static inline int xfs_highbit64(uint64_t v)
+{
+ return fls64(v) - 1;
+}
+
+/* Get low bit set out of 32-bit argument, -1 if none set */
+static inline int xfs_lowbit32(uint32_t v)
+{
+ return ffs(v) - 1;
+}
+
+/* Get low bit set out of 64-bit argument, -1 if none set */
+static inline int xfs_lowbit64(uint64_t v)
+{
+ uint32_t w = (uint32_t)v;
+ int n = 0;
+
+ if (w) { /* lower bits */
+ n = ffs(w);
+ } else { /* upper bits */
+ w = (uint32_t)(v >> 32);
+ if (w) {
+ n = ffs(w);
+ if (n)
+ n += 32;
+ }
+ }
+ return n - 1;
+}
+
+/* Return whether bitmap is empty (1 == empty) */
+extern int xfs_bitmap_empty(uint *map, uint size);
+
+/* Count continuous one bits in map starting with start_bit */
+extern int xfs_contig_bits(uint *map, uint size, uint start_bit);
+
+/* Find next set bit in map */
+extern int xfs_next_bit(uint *map, uint size, uint start_bit);
+
+#endif /* __XFS_BIT_H__ */