Reapply "dm: always update the array size in realloc_argv on success"

This reverts commit a10c89734c.

It should now be fixed so should be safe to apply again.

Change-Id: I9e96304f5118f3bf351eb5b0cb1ef9deade2d42d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/md/dm-table.c

@@ -501,9 +501,10 @@ static char **realloc_argv(unsigned int *size, char **old_argv)
 		gfp = GFP_NOIO;
 	}
 	argv = kmalloc_array(new_size, sizeof(*argv), gfp);
-	if (argv && old_argv) {
-		memcpy(argv, old_argv, *size * sizeof(*argv));
+	if (argv) {
 		*size = new_size;
+		if (old_argv)
+			memcpy(argv, old_argv, *size * sizeof(*argv));
 	}
 
 	kfree(old_argv);