scsi: sbitmap: Export sbitmap_weight

SCSI's .device_busy will be converted to sbitmap and sbitmap_weight is
needed. Export the helper.

The only existing user of sbitmap_weight() uses it to find out how many
bits are set and not cleared. Align sbitmap_weight() meaning with this
usage model.

Link: https://lore.kernel.org/r/20210122023317.687987-6-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

include/linux/sbitmap.h

@@ -341,6 +341,16 @@ static inline int sbitmap_test_bit(struct sbitmap *sb, unsigned int bitnr)
  */
 void sbitmap_show(struct sbitmap *sb, struct seq_file *m);
 
+
+/**
+ * sbitmap_weight() - Return how many set and not cleared bits in a &struct
+ * sbitmap.
+ * @sb: Bitmap to check.
+ *
+ * Return: How many set and not cleared bits set
+ */
+unsigned int sbitmap_weight(const struct sbitmap *sb);
+
 /**
  * sbitmap_bitmap_show() - Write a hex dump of a &struct sbitmap to a &struct
  * seq_file.

lib/sbitmap.c

@@ -334,20 +334,21 @@ static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set)
 	return weight;
 }
 
-static unsigned int sbitmap_weight(const struct sbitmap *sb)
+static unsigned int sbitmap_cleared(const struct sbitmap *sb)
 {
-	return __sbitmap_weight(sb, true);
+	return __sbitmap_weight(sb, false);
 }
 
-static unsigned int sbitmap_cleared(const struct sbitmap *sb)
+unsigned int sbitmap_weight(const struct sbitmap *sb)
 {
-	return __sbitmap_weight(sb, false);
+	return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);
 }
+EXPORT_SYMBOL_GPL(sbitmap_weight);
 
 void sbitmap_show(struct sbitmap *sb, struct seq_file *m)
 {
 	seq_printf(m, "depth=%u\n", sb->depth);
-	seq_printf(m, "busy=%u\n", sbitmap_weight(sb) - sbitmap_cleared(sb));
+	seq_printf(m, "busy=%u\n", sbitmap_weight(sb));
 	seq_printf(m, "cleared=%u\n", sbitmap_cleared(sb));
 	seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);
 	seq_printf(m, "map_nr=%u\n", sb->map_nr);