The contents of the filehandle are defined by the file system and are not examined by any other part of the system. It should contain enough information to uniquely identify a file within the file system as well as noticing when a file has been removed and the file system resources have been reused for a new file. For instance, UFS file system stores the inode number and inode generation counter in its filehandle.
A call to VFS_FHTOVP should generally be preceded by a call to VFS_CHECKEXP(9) to check if the file is accessible to the client.
