bitmap: genericize percpu bitmap region iterators

Bitmaps are fairly popular for their space efficiency, but we don't have
generic iterators available. Make percpu's bitmap region iterators
available to everyone.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index ff335b22f23c..cb63feb3cfbe 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -456,6 +456,41 @@ static inline int bitmap_parse(const char *buf, unsigned int buflen,
 	return __bitmap_parse(buf, buflen, 0, maskp, nmaskbits);
 }
 
+static inline void bitmap_next_clear_region(unsigned long *bitmap,
+					    unsigned int *rs, unsigned int *re,
+					    unsigned int end)
+{
+	*rs = find_next_zero_bit(bitmap, end, *rs);
+	*re = find_next_bit(bitmap, end, *rs + 1);
+}
+
+static inline void bitmap_next_set_region(unsigned long *bitmap,
+					  unsigned int *rs, unsigned int *re,
+					  unsigned int end)
+{
+	*rs = find_next_bit(bitmap, end, *rs);
+	*re = find_next_zero_bit(bitmap, end, *rs + 1);
+}
+
+/*
+ * Bitmap region iterators.  Iterates over the bitmap between [@start, @end).
+ * @rs and @re should be integer variables and will be set to start and end
+ * index of the current clear or set region.
+ */
+#define bitmap_for_each_clear_region(bitmap, rs, re, start, end)	     \
+	for ((rs) = (start),						     \
+	     bitmap_next_clear_region((bitmap), &(rs), &(re), (end));	     \
+	     (rs) < (re);						     \
+	     (rs) = (re) + 1,						     \
+	     bitmap_next_clear_region((bitmap), &(rs), &(re), (end)))
+
+#define bitmap_for_each_set_region(bitmap, rs, re, start, end)		     \
+	for ((rs) = (start),						     \
+	     bitmap_next_set_region((bitmap), &(rs), &(re), (end));	     \
+	     (rs) < (re);						     \
+	     (rs) = (re) + 1,						     \
+	     bitmap_next_set_region((bitmap), &(rs), &(re), (end)))
+
 /**
  * BITMAP_FROM_U64() - Represent u64 value in the format suitable for bitmap.
  * @n: u64 value