f2fs: load inode's flag from disk

This patch fixes missing inode flag loaded from disk, reported by Tom.

[tom@localhost ~]$ sudo mount /dev/loop0 /mnt/
[tom@localhost ~]$ sudo chown tom:tom /mnt/
[tom@localhost ~]$ touch /mnt/testfile
[tom@localhost ~]$ sudo chattr +i /mnt/testfile
[tom@localhost ~]$ echo test > /mnt/testfile
bash: /mnt/testfile: Operation not permitted
[tom@localhost ~]$ rm /mnt/testfile
rm: cannot remove '/mnt/testfile': Operation not permitted
[tom@localhost ~]$ sudo umount /mnt/
[tom@localhost ~]$ sudo mount /dev/loop0 /mnt/
[tom@localhost ~]$ lsattr /mnt/testfile
----i-------------- /mnt/testfile
[tom@localhost ~]$ echo test > /mnt/testfile
[tom@localhost ~]$ rm /mnt/testfile
[tom@localhost ~]$ sudo umount /mnt/

Cc: stable@vger.kernel.org
Reported-by: Tom Yan <tom.ty89@outlook.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -1493,6 +1493,7 @@ static int f2fs_ioc_setflags(struct file *filp, unsigned long arg)
 
 	inode->i_ctime = current_time(inode);
 	f2fs_set_inode_flags(inode);
+	f2fs_mark_inode_dirty_sync(inode, false);
 
 	inode_unlock(inode);
 out:

fs/f2fs/inode.c

@@ -44,7 +44,6 @@ void f2fs_set_inode_flags(struct inode *inode)
 		new_fl |= S_DIRSYNC;
 	inode_set_flags(inode, new_fl,
 			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
-	f2fs_mark_inode_dirty_sync(inode, false);
 }
 
 static void __get_inode_rdev(struct inode *inode, struct f2fs_inode *ri)
@@ -226,6 +225,7 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
 		ret = -EIO;
 		goto bad_inode;
 	}
+	f2fs_set_inode_flags(inode);
 	unlock_new_inode(inode);
 	trace_f2fs_iget(inode);
 	return inode;