2 files changed, 87 insertions, 0 deletions

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 3489253e38fc..dac9dff90350 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -66,6 +66,8 @@
  *  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)
+ *  bitmap_from_arr32(dst, buf, nbits)          Copy nbits from u32[] buf to dst
+ *  bitmap_to_arr32(buf, src, nbits)            Copy nbits from buf to u32[] dst
  *
  */
 
@@ -228,6 +230,35 @@ static inline void bitmap_copy(unsigned long *dst, const unsigned long *src,
 	}
 }
 
+/*
+ * Copy bitmap and clear tail bits in last word.
+ */
+static inline void bitmap_copy_clear_tail(unsigned long *dst,
+		const unsigned long *src, unsigned int nbits)
+{
+	bitmap_copy(dst, src, nbits);
+	if (nbits % BITS_PER_LONG)
+		dst[nbits / BITS_PER_LONG] &= BITMAP_LAST_WORD_MASK(nbits);
+}
+
+/*
+ * On 32-bit systems bitmaps are represented as u32 arrays internally, and
+ * therefore conversion is not needed when copying data from/to arrays of u32.
+ */
+#if BITS_PER_LONG == 64
+extern void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
+							unsigned int nbits);
+extern void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
+							unsigned int nbits);
+#else
+#define bitmap_from_arr32(bitmap, buf, nbits)			\
+	bitmap_copy_clear_tail((unsigned long *) (bitmap),	\
+			(const unsigned long *) (buf), (nbits))
+#define bitmap_to_arr32(buf, bitmap, nbits)			\
+	bitmap_copy_clear_tail((unsigned long *) (buf),		\
+			(const unsigned long *) (bitmap), (nbits))
+#endif
+
 static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
diff --git a/lib/bitmap.c b/lib/bitmap.c
index d8f0c094b18e..47fe6441562c 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -1214,3 +1214,59 @@ void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int n
 }
 EXPORT_SYMBOL(bitmap_copy_le);
 #endif
+
+#if BITS_PER_LONG == 64
+/**
+ * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
+ *	@bitmap: array of unsigned longs, the destination bitmap
+ *	@buf: array of u32 (in host byte order), the source bitmap
+ *	@nbits: number of bits in @bitmap
+ */
+void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
+						unsigned int nbits)
+{
+	unsigned int i, halfwords;
+
+	if (!nbits)
+		return;
+
+	halfwords = DIV_ROUND_UP(nbits, 32);
+	for (i = 0; i < halfwords; i++) {
+		bitmap[i/2] = (unsigned long) buf[i];
+		if (++i < halfwords)
+			bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
+	}
+
+	/* Clear tail bits in last word beyond nbits. */
+	if (nbits % BITS_PER_LONG)
+		bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
+}
+EXPORT_SYMBOL(bitmap_from_arr32);
+
+/**
+ * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
+ *	@buf: array of u32 (in host byte order), the dest bitmap
+ *	@bitmap: array of unsigned longs, the source bitmap
+ *	@nbits: number of bits in @bitmap
+ */
+void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
+{
+	unsigned int i, halfwords;
+
+	if (!nbits)
+		return;
+
+	halfwords = DIV_ROUND_UP(nbits, 32);
+	for (i = 0; i < halfwords; i++) {
+		buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
+		if (++i < halfwords)
+			buf[i] = (u32) (bitmap[i/2] >> 32);
+	}
+
+	/* Clear tail bits in last element of array beyond nbits. */
+	if (nbits % BITS_PER_LONG)
+		buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
+}
+EXPORT_SYMBOL(bitmap_to_arr32);
+
+#endif