sync_inode - write an inode and its pages to disk.
int sync_inode (struct inode * inode, struct writeback_control * wbc);
inode the inode to sync wbc controls the writeback mode
sync_inode will write an inode and its pages to disk. It will also correctly update the inode on its superblock’s dirty inode lists and will update inode->i_state. The caller must have a ref on the inode.