File System Extended Attributes in NFSv4
RFC 8276

Document Type RFC - Proposed Standard (December 2017; Errata)
Last updated 2017-12-05
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Stream WG state Submitted to IESG for Publication
Document shepherd Spencer Shepler
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IESG IESG state RFC 8276 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Spencer Dawkins
Send notices to "Spencer Shepler" <spencer.shepler@gmail.com>
IANA IANA review state Version Changed - Review Needed
IANA action state No IC
Internet Engineering Task Force (IETF)                           M. Naik
Request for Comments: 8276                                       Nutanix
Category: Standards Track                                       M. Eshel
ISSN: 2070-1721                                              IBM Almaden
                                                           December 2017

                File System Extended Attributes in NFSv4

Abstract

   This document describes an optional feature extending the NFSv4
   protocol.  This feature allows extended attributes (hereinafter also
   referred to as xattrs) to be interrogated and manipulated using NFSv4
   clients.  Xattrs are provided by a file system to associate opaque
   metadata, not interpreted by the file system, with files and
   directories.  Such support is present in many modern local file
   systems.  New file attributes are provided to allow clients to query
   the server for xattr support, with that support consisting of new
   operations to get and set xattrs on file system objects.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8276.

Naik & Eshel                 Standards Track                    [Page 1]
RFC 8276              Extended Attributes in NFSv4         December 2017

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Naik & Eshel                 Standards Track                    [Page 2]
RFC 8276              Extended Attributes in NFSv4         December 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Uses of Extended Attributes . . . . . . . . . . . . . . . . .   5
   3.  Functional Gaps Due to Lack of NFSv4 Extended Attribute
       Support . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  File System Support for Extended Attributes . . . . . . . . .   6
   5.  Namespaces  . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Relationship with Named Attributes  . . . . . . . . . . . . .   7
   7.  XDR Description . . . . . . . . . . . . . . . . . . . . . . .   8
     7.1.  Code Components Licensing Notice  . . . . . . . . . . . .   9
     7.2.  XDR for Xattr Extension . . . . . . . . . . . . . . . . .  11
   8.  Protocol Extensions . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  New Definitions . . . . . . . . . . . . . . . . . . . . .  11
     8.2.  New Attribute . . . . . . . . . . . . . . . . . . . . . .  12
       8.2.1.  xattr_support . . . . . . . . . . . . . . . . . . . .  12
     8.3.  New Error Definitions . . . . . . . . . . . . . . . . . .  12
       8.3.1.  NFS4ERR_NOXATTR (Error Code 10095)  . . . . . . . . .  12
       8.3.2.  NFS4ERR_XATTR2BIG (Error Code 10096)  . . . . . . . .  13
     8.4.  New Operations  . . . . . . . . . . . . . . . . . . . . .  13
       8.4.1.  GETXATTR - Get an Extended Attribute of a File  . . .  14
       8.4.2.  SETXATTR - Set an Extended Attribute of a File  . . .  15
       8.4.3.  LISTXATTRS - List Extended Attributes of a File . . .  17
       8.4.4.  REMOVEXATTR - Remove an Extended Attribute of a File   18
       8.4.5.  Valid Errors  . . . . . . . . . . . . . . . . . . . .  19
     8.5.  Modifications to Existing Operations  . . . . . . . . . .  21
     8.6.  Numeric Values Assigned to Protocol Extensions  . . . . .  22
     8.7.  Caching . . . . . . . . . . . . . . . . . . . . . . . . .  23
     8.8.  Xattrs and File Locking . . . . . . . . . . . . . . . . .  25
     8.9.  pNFS Considerations . . . . . . . . . . . . . . . . . . .  25
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  25
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  25
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  26
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