NAME

       vfs_fileid - Generates file_id structs with unique device id values for cluster setups

SYNOPSIS

       vfs objects = fileid

DESCRIPTION

       This VFS module is part of the samba(7) suite.

       Samba uses file_id structs to uniquely identify files for locking purpose. By default the
       file_id contains the device and inode number returned by the stat() system call. As the
       file_id is a unique identifier of a file, it must be the same on all nodes in a cluster
       setup. This module overloads the SMB_VFS_FILE_ID_CREATE() operation and generates the
       device number based on the configured algorithm (see the "fileid:algorithm" option).

       When using the fsname or fsid algorithm a stat() and statfs() call is required for all
       mounted file systems to generate the file_id. If e.g. an NFS file system is unresponsive
       such a call might block and the smbd process will become unresponsive. Use the
       "fileid:fstype deny", "fileid:fstype allow", "fileid:mntdir deny", or "fileid:mntdir
       allow" options to ignore potentially unresponsive file systems.

OPTIONS

       fileid:algorithm = ALGORITHM
           Available algorithms are fsname, fsname_nodirs, fsid and hostname. The default value
           is fsname.

           The fsname algorithm generates device id by hashing the kernel device name.

           The fsname_nodirs algorithm generates device id by hashing the kernel device name for
           files and by hashing the hostname for directories. This can be used to deliberately
           break lock coherency for directories in a cluster.

           The fsid algorithm generates the device id from the f_fsid returned from the statfs()
           syscall.

           The hostname algorithm generates device id by hashing the hostname. This can be used
           to deliberately break lock coherency in a cluster.

           The fsname_norootdir algorithm generates device ids by hashing the kernel device name,
           except for the root directory of shares where it will use the hostname algorithm. This
           can be used to deliberately break lock coherency in a cluster for the root directory
           of a share.

           The fsname_norootdir_ext algorithm generates device ids by hashing the kernel device
           name, except for the root directory of shares where it will use the hostname
           algorithm. Additionally it generates an extid based on the process pid. This can be
           used to deliberately break lock coherency between all smbd processes in the whole
           cluster for the root directory of a share.

       fileid:mapping = ALGORITHM
           This option is the legacy version of the fileid:algorithm option, which was used in
           earlier versions of fileid mapping feature in custom Samba 3.0 versions.

       fileid:fstype deny = LIST
           List of file system types to be ignored for file_id generation.

       fileid:fstype allow = LIST
           List of file system types to be allowed for file_id generation. If this option is set,
           file system types not listed here are ignored.

       fileid:mntdir deny = LIST
           List of file system mount points to be ignored for file_id generation.

       fileid:mntdir allow = LIST
           List of file system mount points to be allowed for file_id generation. If this option
           is set, file system mount points not listed here are ignored.

       fileid:nolockinode
           This option triggers use of the fileid hostname algorithm for the configured inode
           which can be used to deliberately break lock coherency for the corresponding file or
           directory in a cluster.

EXAMPLES

       Usage of the fileid module with the fsid algorithm:

                   [global]
                vfs objects = fileid
                fileid:algorithm = fsid

VERSION

       This man page is part of version 4.15.13-Ubuntu of the Samba suite.

AUTHOR

       The original Samba software and related utilities were created by Andrew Tridgell. Samba
       is now developed by the Samba Team as an Open Source project similar to the way the Linux
       kernel is developed.