|VFS_FILEID(8)||System Administration tools||VFS_FILEID(8)|
vfs_fileid - Generates file_id structs with unique device id values for cluster setups. It also adds ways to deliberately break lock coherency for specific inodes
vfs objects = fileid
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.
fileid:algorithm = ALGORITHM
The fsname algorithm generates device id by hashing the kernel device name.
The fsid algorithm generates the device id from the f_fsid returned from the statfs() syscall.
The next_module algorithm lets the next vfs module in the module chain generate the id. This is mainly used in combination with the various 'nolock' features the fileid module provides.
The legacy hostname algorithm generates unique devid by hashing the hostname and low level device id. It also implies fileid:nolock_all_inodes=yes. This can be used to deliberately break lock coherency in a cluster and with fileid:nolock_max_slots also between local processes within a node. NOTE: Do not use this without knowing what you are doing! It breaks SMB semantics and it can lead to data corruption! This implies fileid:nolock_all_inodes=yes.
The legacy fsname_nodirs algorithm is an alias for using the fsname algorithm together with fileid:nolock_all_dirs=yes. NOTE: Do not use this without knowing what you are doing! It breaks SMB semantics! See fileid:nolock_paths for a more fine grained approach.
The legacy fsname_norootdir algorithm is an alias for using the fsname algorithm together with fileid:nolock_paths= “.”. It means this can be used to deliberately break lock coherency in a cluster for the root directory of a share.
The legacy fsname_norootdir_ext algorithm is an alias for using the fsname algorithm together with fileid:nolock_paths= “.” and fileid:nolock_max_slots = 18446744073709551615. It means this can be used to deliberately break lock coherency completely for the root directory of a share. Even local processes are no longer lock coherent.
fileid:mapping = ALGORITHM
fileid:fstype deny = LIST
fileid:fstype allow = LIST
fileid:mntdir deny = LIST
fileid:mntdir allow = LIST
fileid:nolock_max_slots = NUMBER(1-18446744073709551615)
fileid:nolock_all_dirs = BOOL
fileid:nolock_all_inodes = BOOL
fileid:nolock_paths = LIST
fileid:nolockinode = NUMBER
Usage of the fileid module with the fsid algorithm:
[global] vfs objects = fileid fileid:algorithm = fsid
Usage of the fileid module in order avoid load on heavily contended (most likely read-only) inodes.
[global] vfs objects = fileid fileid:algorithm = next_module fileid:nolock_paths = . ContendedFolder1 /path/to/contended.exe fileid:nolock_max_slots = 256
This man page is part of version 4.18.3 of the Samba suite.
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.