zram: use zram_free_page instead of open-coded

The zram_free_page already handles NULL handle case and same page so use
it to reduce error probability.  (Acutaully, I made a mistake when I
handled same page feature)

Link: http://lkml.kernel.org/r/1492052365-16169-7-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/zram/zram_drv.c

@@ -480,17 +480,8 @@ static void zram_meta_free(struct zram *zram, u64 disksize)
 	size_t index;
 
 	/* Free all pages that are still in this zram device */
-	for (index = 0; index < num_pages; index++) {
-		unsigned long handle = zram_get_handle(zram, index);
-		/*
-		 * No memory is allocated for same element filled pages.
-		 * Simply clear same page flag.
-		 */
-		if (!handle || zram_test_flag(zram, index, ZRAM_SAME))
-			continue;
-
-		zs_free(zram->mem_pool, handle);
-	}
+	for (index = 0; index < num_pages; index++)
+		zram_free_page(zram, index);
 
 	zs_destroy_pool(zram->mem_pool);
 	vfree(zram->table);
@@ -978,9 +969,6 @@ static void zram_reset_device(struct zram *zram)
 
 	comp = zram->comp;
 	disksize = zram->disksize;
-
-	/* Reset stats */
-	memset(&zram->stats, 0, sizeof(zram->stats));
 	zram->disksize = 0;
 
 	set_capacity(zram->disk, 0);
@@ -989,6 +977,7 @@ static void zram_reset_device(struct zram *zram)
 	up_write(&zram->init_lock);
 	/* I/O operation under all of CPU are done so let's free */
 	zram_meta_free(zram, disksize);
+	memset(&zram->stats, 0, sizeof(zram->stats));
 	zcomp_destroy(comp);
 }