lib/bitmap.c: conversion routines to/from u32 array

Aimed at transferring bitmaps to/from user-space in a 32/64-bit agnostic
way.

Tested:
  unit tests (next patch) on qemu i386, x86_64, ppc, ppc64 BE and LE,
  ARM.

Signed-off-by: David Decotigny <decot@googlers.com>
Reviewed-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 9653fdb..e9b0b9a 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -59,6 +59,8 @@
  * bitmap_find_free_region(bitmap, bits, order)	Find and allocate bit region
  * bitmap_release_region(bitmap, pos, order)	Free specified bit region
  * bitmap_allocate_region(bitmap, pos, order)	Allocate specified bit region
+ * bitmap_from_u32array(dst, nbits, buf, nwords) *dst = *buf (nwords 32b words)
+ * bitmap_to_u32array(buf, nwords, src, nbits)	*buf = *dst (nwords 32b words)
  */
 
 /*
@@ -163,6 +165,14 @@
 extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
 extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
 extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
+extern unsigned int bitmap_from_u32array(unsigned long *bitmap,
+					 unsigned int nbits,
+					 const u32 *buf,
+					 unsigned int nwords);
+extern unsigned int bitmap_to_u32array(u32 *buf,
+				       unsigned int nwords,
+				       const unsigned long *bitmap,
+				       unsigned int nbits);
 #ifdef __BIG_ENDIAN
 extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
 #else