btrfs: use list_for_each_entry_safe in free-space-cache.c

Use list_for_each_entry_safe() instead of list_for_each_safe() to
simplify the code.
Signed-off-by: NGeliang Tang <geliangtang@163.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/free-space-cache.c

@@ -1086,14 +1086,11 @@ write_pinned_extent_entries(struct btrfs_root *root,
 static noinline_for_stack int
 write_bitmap_entries(struct btrfs_io_ctl *io_ctl, struct list_head *bitmap_list)
 {
-	struct list_head *pos, *n;
+	struct btrfs_free_space *entry, *next;
 	int ret;
 
 	/* Write out the bitmaps */
-	list_for_each_safe(pos, n, bitmap_list) {
-		struct btrfs_free_space *entry =
-			list_entry(pos, struct btrfs_free_space, list);
-
+	list_for_each_entry_safe(entry, next, bitmap_list, list) {
 		ret = io_ctl_add_bitmap(io_ctl, entry->bitmap);
 		if (ret)
 			return -ENOSPC;
@@ -1119,13 +1116,10 @@ static int flush_dirty_cache(struct inode *inode)
 static void noinline_for_stack
 cleanup_bitmap_list(struct list_head *bitmap_list)
 {
-	struct list_head *pos, *n;
+	struct btrfs_free_space *entry, *next;
 
-	list_for_each_safe(pos, n, bitmap_list) {
-		struct btrfs_free_space *entry =
-			list_entry(pos, struct btrfs_free_space, list);
+	list_for_each_entry_safe(entry, next, bitmap_list, list)
 		list_del_init(&entry->list);
-	}
 }
 
 static void noinline_for_stack