dm vdo: Update code to use mem_is_zero

Remove function that would check if data was all zeroes. Use the
built-in kernel function mem_is_zero() instead.

Signed-off-by: Bruce Johnston <bjohnsto@redhat.com>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

Author: bjohnsto

drivers/md/dm-vdo/data-vio.c

@@ -17,6 +17,7 @@
 #include <linux/minmax.h>
 #include <linux/sched.h>
 #include <linux/spinlock.h>
+#include <linux/string.h>
 #include <linux/wait.h>
 
 #include "logger.h"
@@ -509,18 +510,6 @@ static void launch_data_vio(struct data_vio *data_vio, logical_block_number_t lb
 	vdo_enqueue_completion(completion, VDO_DEFAULT_Q_MAP_BIO_PRIORITY);
 }
 
-static bool is_zero_block(char *block)
-{
-	int i;
-
-	for (i = 0; i < VDO_BLOCK_SIZE; i += sizeof(u64)) {
-		if (*((u64 *) &block[i]))
-			return false;
-	}
-
-	return true;
-}
-
 static void copy_from_bio(struct bio *bio, char *data_ptr)
 {
 	struct bio_vec biovec;
@@ -572,7 +561,7 @@ static void launch_bio(struct vdo *vdo, struct data_vio *data_vio, struct bio *b
 		 * we acknowledge the bio.
 		 */
 		copy_from_bio(bio, data_vio->vio.data);
-		data_vio->is_zero = is_zero_block(data_vio->vio.data);
+		data_vio->is_zero = mem_is_zero(data_vio->vio.data, VDO_BLOCK_SIZE);
 		data_vio->write = true;
 	}
 
@@ -1459,7 +1448,7 @@ static void modify_for_partial_write(struct vdo_completion *completion)
 		copy_from_bio(bio, data + data_vio->offset);
 	}
 
-	data_vio->is_zero = is_zero_block(data);
+	data_vio->is_zero = mem_is_zero(data, VDO_BLOCK_SIZE);
 	data_vio->read = false;
 	launch_data_vio_logical_callback(data_vio,
 					 continue_data_vio_with_block_map_slot);