dm zone: Use the bitmap API to allocate bitmaps

Use bitmap_zalloc()/bitmap_free() instead of hand-writing them.
It is less verbose and it improves the semantic.

Signed-off-by: Christophe JAILLET <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>

drivers/md/dm-zone.c

···
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
+#include <linux/bitmap.h>
 
 #include "dm-core.h"
 
···
 void dm_cleanup_zoned_dev(struct mapped_device *md)
 {
 	if (md->disk) {
-		kfree(md->disk->conv_zones_bitmap);
+		bitmap_free(md->disk->conv_zones_bitmap);
 		md->disk->conv_zones_bitmap = NULL;
-		kfree(md->disk->seq_zones_wlock);
+		bitmap_free(md->disk->seq_zones_wlock);
 		md->disk->seq_zones_wlock = NULL;
 	}
 
···
 	switch (zone->type) {
 	case BLK_ZONE_TYPE_CONVENTIONAL:
 		if (!disk->conv_zones_bitmap) {
-			disk->conv_zones_bitmap =
-				kcalloc(BITS_TO_LONGS(disk->nr_zones),
-					sizeof(unsigned long), GFP_NOIO);
+			disk->conv_zones_bitmap = bitmap_zalloc(disk->nr_zones,
+								GFP_NOIO);
 			if (!disk->conv_zones_bitmap)
 				return -ENOMEM;
 		}
···
 	case BLK_ZONE_TYPE_SEQWRITE_REQ:
 	case BLK_ZONE_TYPE_SEQWRITE_PREF:
 		if (!disk->seq_zones_wlock) {
-			disk->seq_zones_wlock =
-				kcalloc(BITS_TO_LONGS(disk->nr_zones),
-					sizeof(unsigned long), GFP_NOIO);
+			disk->seq_zones_wlock = bitmap_zalloc(disk->nr_zones,
+							      GFP_NOIO);
 			if (!disk->seq_zones_wlock)
 				return -ENOMEM;
 		}