f2fs: don't track new nat entry in nat set

Nat entry set is used only in checkpoint(), and during checkpoint() we
won't flush new nat entry with unallocated address, so we don't need to
add new nat entry into nat set, then nat_entry_set::entry_cnt can
indicate actual entry count we need to flush in checkpoint().

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/node.c

@@ -193,8 +193,8 @@ static void __del_from_nat_cache(struct f2fs_nm_info *nm_i, struct nat_entry *e)
 	__free_nat_entry(e);
 }
 
-static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
-						struct nat_entry *ne)
+static struct nat_entry_set *__grab_nat_entry_set(struct f2fs_nm_info *nm_i,
+							struct nat_entry *ne)
 {
 	nid_t set = NAT_BLOCK_OFFSET(ne->ni.nid);
 	struct nat_entry_set *head;
@@ -209,15 +209,36 @@ static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
 		head->entry_cnt = 0;
 		f2fs_radix_tree_insert(&nm_i->nat_set_root, set, head);
 	}
+	return head;
+}
+
+static void __set_nat_cache_dirty(struct f2fs_nm_info *nm_i,
+						struct nat_entry *ne)
+{
+	struct nat_entry_set *head;
+	bool new_ne = nat_get_blkaddr(ne) == NEW_ADDR;
+
+	if (!new_ne)
+		head = __grab_nat_entry_set(nm_i, ne);
+
+	/*
+	 * update entry_cnt in below condition:
+	 * 1. update NEW_ADDR to valid block address;
+	 * 2. update old block address to new one;
+	 */
+	if (!new_ne && (get_nat_flag(ne, IS_PREALLOC) ||
+				!get_nat_flag(ne, IS_DIRTY)))
+		head->entry_cnt++;
+
+	set_nat_flag(ne, IS_PREALLOC, new_ne);
 
 	if (get_nat_flag(ne, IS_DIRTY))
 		goto refresh_list;
 
 	nm_i->dirty_nat_cnt++;
-	head->entry_cnt++;
 	set_nat_flag(ne, IS_DIRTY, true);
 refresh_list:
-	if (nat_get_blkaddr(ne) == NEW_ADDR)
+	if (new_ne)
 		list_del_init(&ne->list);
 	else
 		list_move_tail(&ne->list, &head->entry_list);

fs/f2fs/node.h

@@ -44,6 +44,7 @@ enum {
 	HAS_FSYNCED_INODE,	/* is the inode fsynced before? */
 	HAS_LAST_FSYNC,		/* has the latest node fsync mark? */
 	IS_DIRTY,		/* this nat entry is dirty? */
+	IS_PREALLOC,		/* nat entry is preallocated */
 };
 
 /*