f2fs: do not write any node pages related to orphan inodes

We should not write node pages when deleting orphan inodes.
In order to do that, we can eaisly set POR_DOING flag earlier before entering
orphan inode routine.

Reviewed-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -497,8 +497,6 @@ int recover_orphan_inodes(struct f2fs_sb_info *sbi)
 	if (!is_set_ckpt_flags(F2FS_CKPT(sbi), CP_ORPHAN_PRESENT_FLAG))
 		return 0;
 
-	set_sbi_flag(sbi, SBI_POR_DOING);
-
 	start_blk = __start_cp_addr(sbi) + 1 + __cp_payload(sbi);
 	orphan_blocks = __start_sum_addr(sbi) - 1 - __cp_payload(sbi);
 
@@ -514,7 +512,6 @@ int recover_orphan_inodes(struct f2fs_sb_info *sbi)
 			err = recover_orphan_inode(sbi, ino);
 			if (err) {
 				f2fs_put_page(page, 1);
-				clear_sbi_flag(sbi, SBI_POR_DOING);
 				return err;
 			}
 		}
@@ -522,7 +519,6 @@ int recover_orphan_inodes(struct f2fs_sb_info *sbi)
 	}
 	/* clear Orphan Flag */
 	clear_ckpt_flags(F2FS_CKPT(sbi), CP_ORPHAN_PRESENT_FLAG);
-	clear_sbi_flag(sbi, SBI_POR_DOING);
 	return 0;
 }
 

fs/f2fs/recovery.c

@@ -545,14 +545,12 @@ int recover_fsync_data(struct f2fs_sb_info *sbi)
 
 	INIT_LIST_HEAD(&inode_list);
 
-	/* step #1: find fsynced inode numbers */
-	set_sbi_flag(sbi, SBI_POR_DOING);
-
 	/* prevent checkpoint */
 	mutex_lock(&sbi->cp_mutex);
 
 	blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
 
+	/* step #1: find fsynced inode numbers */
 	err = find_fsync_dnodes(sbi, &inode_list);
 	if (err)
 		goto out;

fs/f2fs/super.c

@@ -1165,7 +1165,9 @@ try_onemore:
 	mutex_init(&sbi->writepages);
 	mutex_init(&sbi->cp_mutex);
 	init_rwsem(&sbi->node_write);
-	clear_sbi_flag(sbi, SBI_POR_DOING);
+
+	/* disallow all the data/node/meta page writes */
+	set_sbi_flag(sbi, SBI_POR_DOING);
 	spin_lock_init(&sbi->stat_lock);
 
 	init_rwsem(&sbi->read_io.io_rwsem);
@@ -1309,6 +1311,8 @@ try_onemore:
 			goto free_kobj;
 		}
 	}
+	/* recover_fsync_data() cleared this already */
+	clear_sbi_flag(sbi, SBI_POR_DOING);
 
 	/*
 	 * If filesystem is not mounted as read-only then