Documentation/filesystems/nfs/nfs41-server.rst

Source file repositories/reference/linux-study-clean/Documentation/filesystems/nfs/nfs41-server.rst

File Facts

System: Linux kernel
Corpus path: Documentation/filesystems/nfs/nfs41-server.rst
Extension: .rst
Size: 22453 bytes
Lines: 257
Domain: Support Tooling And Documentation
Bucket: Documentation
Inferred role: Support Tooling And Documentation: documentation
Status: atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

No C-style include directives detected by the generator.

Detected Declarations

No top-level syscall, struct, function, initcall, or export declaration detected by the generator.

Annotated Snippet

=============================
NFSv4.1 Server Implementation
=============================

Server support for minorversion 1 can be controlled using the
/proc/fs/nfsd/versions control file.  The string output returned
by reading this file will contain either "+4.1" or "-4.1"
correspondingly.

Currently, server support for minorversion 1 is enabled by default.
It can be disabled at run time by writing the string "-4.1" to
the /proc/fs/nfsd/versions control file.  Note that to write this
control file, the nfsd service must be taken down.  You can use rpc.nfsd
for this; see rpc.nfsd(8).

(Warning: older servers will interpret "+4.1" and "-4.1" as "+4" and
"-4", respectively.  Therefore, code meant to work on both new and old
kernels must turn 4.1 on or off *before* turning support for version 4
on or off; rpc.nfsd does this correctly.)

The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
on RFC 5661.

From the many new features in NFSv4.1 the current implementation
focuses on the mandatory-to-implement NFSv4.1 Sessions, providing
"exactly once" semantics and better control and throttling of the
resources allocated for each client.

The table below, taken from the NFSv4.1 document, lists
the operations that are mandatory to implement (REQ), optional
(OPT), and NFSv4.0 operations that are required not to implement (MNI)
in minor version 1.  The first column indicates the operations that
are not supported yet by the linux server implementation.

The OPTIONAL features identified and their abbreviations are as follows:

- **pNFS**	Parallel NFS
- **FDELG**	File Delegations
- **DDELG**	Directory Delegations

The following abbreviations indicate the linux server implementation status.

- **I**	Implemented NFSv4.1 operations.
- **NS**	Not Supported.
- **NS\***	Unimplemented optional feature.

Operations
==========

+-----------------------+----------------------+---------------------+---------------------------+----------------+
| Implementation status | Operation            | REQ,REC, OPT or NMI | Feature (REQ, REC or OPT) | Definition     |
+=======================+======================+=====================+===========================+================+
|                       | ACCESS               | REQ                 |                           | Section 18.1   |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
| I                     | BACKCHANNEL_CTL      | REQ                 |                           | Section 18.33  |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
| I                     | BIND_CONN_TO_SESSION | REQ                 |                           | Section 18.34  |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
|                       | CLOSE                | REQ                 |                           | Section 18.2   |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
|                       | COMMIT               | REQ                 |                           | Section 18.3   |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
|                       | CREATE               | REQ                 |                           | Section 18.4   |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
| I                     | CREATE_SESSION       | REQ                 |                           | Section 18.36  |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
| NS*                   | DELEGPURGE           | OPT                 | FDELG (REQ)               | Section 18.5   |
+-----------------------+----------------------+---------------------+---------------------------+----------------+
|                       | DELEGRETURN          | OPT                 | FDELG,                    | Section 18.6   |
+-----------------------+----------------------+---------------------+---------------------------+----------------+

Annotation

Atlas domain: Support Tooling And Documentation / Documentation.
Implementation status: atlas-only.

Implementation Notes

This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.