Extending the Opening of Files in NFSv4.2
draft-ietf-nfsv4-delstid-08

Network File System Version 4                                  T. Haynes
Internet-Draft                                              T. Myklebust
Intended status: Standards Track                             Hammerspace
Expires: 5 April 2025                                     2 October 2024

               Extending the Opening of Files in NFSv4.2
                      draft-ietf-nfsv4-delstid-08

Abstract

   The Network File System v4 (NFSv4) allows a client to both open a
   file and be granted a delegation of that file.  This delegation
   provides the client the right to authoritatively cache metadata on
   the file locally.  This document presents several extensions for both
   the opening and delegating of the file to the client.  This document
   extends NFSv4.2 (see RFC7863).

Note

   This note is to be removed before publishing as an RFC.

   Discussion of this draft takes place on the NFSv4 working group
   mailing list (nfsv4@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/nfsv4/.  Working Group
   information can be found at https://datatracker.ietf.org/wg/nfsv4/
   about/.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 5 April 2025.

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Copyright Notice

   Copyright (c) 2024 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/
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Offline Files . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  XDR for Offline Attribute . . . . . . . . . . . . . . . .   4
   3.  Determining OPEN Feature Support  . . . . . . . . . . . . . .   5
     3.1.  XDR for Open Arguments  . . . . . . . . . . . . . . . . .   5
   4.  OPEN grants only one of Open or Delegation Stateid  . . . . .   7
     4.1.  Implementation Experience . . . . . . . . . . . . . . . .   8
   5.  Proxying of Times . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Use case: NFSv3 client proxy  . . . . . . . . . . . . . .  11
     5.2.  XDR for Proxying of Times . . . . . . . . . . . . . . . .  11
   6.  Extraction of XDR . . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   In the Network File System version4 (NFSv4), a client may be granted
   a delegation for a file (see Section 1.8.4 of [RFC8881]).  This
   allows the client to act as the authority for the file's metadata and
   data.  This document presents a number of extensions which enhance
   the functionality of opens and delegations.  These allow the client
   to:

   *  detect an offline file, which may require significant effort to
      obtain.

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   *  determine which extensions of OPEN (see Section 18.16 of
      [RFC8881]) flags are supported by the server.

   *  during the OPEN procedure, retrieve either the open stateid (see
      Section 8.2 of [RFC8881]) or delegation stateid, but not both
      simultaneously.

   *  cache both the access and modify timestamps, thereby reducing the
      frequency with which the client must query the server for this
      information.

   Using the process detailed in [RFC8178], the revisions in this
   document become an extension of NFSv4.2 [RFC7862].  They are built on
   top of the external data representation (XDR) [RFC4506] generated
   from [RFC7863].

1.1.  Definitions

   offline file:  A file which exists on a device which is not connected
      to the server.  There is typically a cost associated with bringing
      the file to an online status.  Historically this would be a file
      on tape media and the cost would have been finding and loading the
      tape.  A more modern interpretation is that the file is in the
      cloud and the cost is a monetary one in downloading the file.

   proxy:  Proxying of attributes occurs when a client has the
      authority, as granted by the appropriate delegation, to represent
      the attributes normally maintained by the server.  For read
      attributes, this occurs when the client has either a read or write
      delegations for the file.  For write attributes, this occurs when
      the client has a write delegation for the file.  The client having
      this authority is the "proxy" for those attributes.

1.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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2.  Offline Files

   If a file is offline, then the server has immediate high-performance
   access to the file's attributes, but not to the file's content.  The
   action of retrieving the data content is expensive, to the extent
   that the content should only be retrieved if it is going to be used.
   For example, a graphical file manager (such as OSX's Finder) may want
   to access the beginning of the file to preview it for an user who is
   hovering their pointer over the file name and not accessing it
   otherwise.  If the file is retrieved, it will most likely either be
   immediately thrown away or returned.

   A compound (see Section 2.3 of [RFC8881]) with a GETATTR (see
   Section 18.7 of [RFC8881]) or READDIR (see Section 18.23 of
   [RFC8881]) can report the file's attributes without bringing the file
   online.  However, either an OPEN or a LAYOUTGET (see Section 18.43 of
   [RFC8881]) might cause the file server to retrieve the archived data
   contents, bringing the file online.  For non-parallel NFS (pNFS)
   systems (see Section 12 of [RFC8881]) , the OPEN operation requires a
   filehandle to the data content.  For pNFS systems, the filehandle
   retrieved from an OPEN need not cause the data content to be
   retrieved.  But when the LAYOUTGET operation is processed, a layout
   type specific mapping will cause the data content to be retrieved
   from offline storage.

   If the client is not aware that the file is offline, it might
   inadvertently open the file to determine what type of file it is
   accessing.  By interrogating the new attribute fattr4_offline, a
   client can predetermine the availability of the file, avoiding the
   need to open it at all.  Being offline might also involve situations
   in which the file is archived in the cloud, i.e., there can be an
   expense in both retrieving the file to bring online and in sending
   the file back to offline status.

2.1.  XDR for Offline Attribute

   <CODE BEGINS>
   ///
   /// typedef bool            fattr4_offline;
   ///
   ///
   /// const FATTR4_OFFLINE            = 83;
   ///
   <CODE ENDS>

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3.  Determining OPEN Feature Support

   [RFC8178] (see Section 4.4.2) allows for extending a particular minor
   version of the NFSv4 protocol without requiring the definition of a
   new minor version.  The client can probe the capabilities of the
   server and based on the result, determine if both it and the server
   support optional features not previously specified as part of the
   minor version.

   The fattr4_open_arguments attribute is a new XDR extension which
   provides helpful support when the OPEN procedure is extended in such
   a fashion.  It models all of the parameters via bitmap4 data
   structures, which allows for the addition of a new flag to any of the
   OPEN arguments (see Section 18.16.1 of [RFC8881]).  The scope of this
   attribute applies to all objects with a matching fsid.

   Two new flags are provided:

   *  OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION (see Section 4)

   *  OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS (see Section 5)

   Subsequent extensions can use this framework when introducing new
   OPTIONAL functionality to OPEN, by creating a new flag for each
   OPTIONAL parameter.

   Since fattr4_open_arguments is a RECOMMENDED attribute, if the server
   informs the client via NFS4ERR_ATTRNOTSUPP that it does not support
   this new attribute, the client MUST take this to mean that the
   additional new OPTIONAL functionality to OPEN is also not supported.

   Some other concerns are how to process both currently REQUIRED flags
   and OPTIONAL flags which become REQUIRED in the future.  The server
   MUST mark REQUIRED flags as being supported.  Note that these flags
   MUST only change from OPTIONAL to REQUIRED when the NFSv4 minor
   version is incremented.

3.1.  XDR for Open Arguments

   <CODE BEGINS>
   ///
   /// struct open_arguments4 {
   ///   bitmap4  oa_share_access;
   ///   bitmap4  oa_share_deny;
   ///   bitmap4  oa_share_access_want;
   ///   bitmap4  oa_open_claim;
   ///   bitmap4  oa_create_mode;
   /// };

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   ///
   ///
   /// enum open_args_share_access4 {
   ///    OPEN_ARGS_SHARE_ACCESS_READ  = 1,
   ///    OPEN_ARGS_SHARE_ACCESS_WRITE = 2,
   ///    OPEN_ARGS_SHARE_ACCESS_BOTH  = 3
   /// };
   ///
   ///
   /// enum open_args_share_deny4 {
   ///    OPEN_ARGS_SHARE_DENY_NONE  = 0,
   ///    OPEN_ARGS_SHARE_DENY_READ  = 1,
   ///    OPEN_ARGS_SHARE_DENY_WRITE = 2,
   ///    OPEN_ARGS_SHARE_DENY_BOTH  = 3
   /// };
   ///
   ///
   /// enum open_args_share_access_want4 {
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_ANY_DELEG           = 3,
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_NO_DELEG            = 4,
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_CANCEL              = 5,
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_SIGNAL_DELEG_WHEN_RESRC_AVAIL
   ///                                                    = 17,
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_PUSH_DELEG_WHEN_UNCONTENDED
   ///                                                    = 18,
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS    = 20,
   ///    OPEN_ARGS_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION = 21
   /// };
   ///
   ///
   /// enum open_args_open_claim4 {
   ///    OPEN_ARGS_OPEN_CLAIM_NULL          = 0,
   ///    OPEN_ARGS_OPEN_CLAIM_PREVIOUS      = 1,
   ///    OPEN_ARGS_OPEN_CLAIM_DELEGATE_CUR  = 2,
   ///    OPEN_ARGS_OPEN_CLAIM_DELEGATE_PREV = 3,
   ///    OPEN_ARGS_OPEN_CLAIM_FH            = 4,
   ///    OPEN_ARGS_OPEN_CLAIM_DELEG_CUR_FH  = 5,
   ///    OPEN_ARGS_OPEN_CLAIM_DELEG_PREV_FH = 6
   /// };
   ///
   ///
   /// enum open_args_createmode4 {
   ///    OPEN_ARGS_CREATEMODE_UNCHECKED4     = 0,
   ///    OPEN_ARGS_CREATE_MODE_GUARDED       = 1,
   ///    OPEN_ARGS_CREATEMODE_EXCLUSIVE4     = 2,
   ///    OPEN_ARGS_CREATE_MODE_EXCLUSIVE4_1  = 3
   /// };
   ///

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   ///
   /// typedef open_arguments4 fattr4_open_arguments;
   ///
   ///
   /// %/*
   /// % * Determine what OPEN supports.
   /// % */
   /// const FATTR4_OPEN_ARGUMENTS     = 86;
   ///
   ///
   /// const OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION = 0x200000;
   ///
   ///
   /// const OPEN4_RESULT_NO_OPEN_STATEID = 0x00000010;
   ///
   <CODE ENDS>

4.  OPEN grants only one of Open or Delegation Stateid

   The OPEN (See Section 18.16 of [RFC8881]) procedure returns an open
   stateid to the client to reference the state of the file.  The client
   could also request a delegation stateid in the OPEN arguments.  The
   file can be considered open for the client as long as the count of
   open and delegated stateids is greater than 0.  Either type of
   stateid is sufficient to enable the server to treat the file as if it
   were open, which allows READ (See Section 18.25 of [RFC8881]), WRITE
   (See Section 18.38 of [RFC8881]), LOCK (See Section 18.12 of
   [RFC8881]), and LAYOUTGET (see Section 18.50 of [RFC8881]) operations
   to proceed.  If the client gets both an open and a delegation stateid
   as part of the OPEN, then it has to return them both to the server.
   A further consideration is that during each operation, the client can
   send a costly GETATTR (See Section 18.7 of [RFC8881]).

   If the client knows that the server supports the
   OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION flag (as determined by an
   earlier GETATTR operation which queried for the fattr4_open_arguments
   attribute), then the client can supply that flag during the OPEN and
   only get either an open or delegation stateid.

   The client is already prepared to not get a delegation stateid even
   if requested.  In order to not send an open stateid, the server MUST
   indicate that fact with the result flag of
   OPEN4_RESULT_NO_OPEN_STATEID.  The open stateid field,
   OPEN4resok.stateid (see Section 18.16.2 of [RFC8881]), MUST be set to
   the special all zero stateid in this case.

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   Note that the OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION flag is a
   hint.  The server might return both stateids.  Consider the scenario
   in which the client opens a file read-only (with
   OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION set) and gets only an
   open stateid.  If the client then opens the file for read-write (with
   OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION set), then the server has
   three options:

   1.  Only an open stateid with the correct seqid.

   2.  Only a delegation stateid with the open stateid now having an
       incorrect seqid as it needs to be upgraded.

   3.  Both an open (which will be upgraded) and a delegation stateid.

   In this scenario, returning just a delegation stateid would hide
   information from the client.  If the client already has an open
   stateid, then the server SHOULD ignore the
   OPEN4_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION flag and return both the
   open and delegation stateids.

4.1.  Implementation Experience

   The CLOSE operation (see Section 18.2 of [RFC8881]) neither
   explicitly nor implicitly releases any delegation stateids.  This is
   not symmetrical with the OPEN operation, which can grant both an open
   and a delegation stateid.  This specification could have tried to
   extend the CLOSE operation to release both stateids, but
   implementation experience shows that is more costly than the approach
   which has been proposed.

   Consider a small workload of creating a file with content.  That
   takes 3 synchronous and 1 asynchronous operations with existing
   implementations.  The first synchronous one has to OPEN the file, the
   second synchronous one performs the WRITE to the file, the third
   synchronous one has to CLOSE the file, and the fourth asynchronous
   one uses DELEGRETURN (see Section 18.6 of [RFC8881]) to return the
   delegation stateid.

   <CODE BEGINS>
         SEQ PUTFH OPEN GETFH GETATTR
         SEQ PUTFH WRITE GETATTR
         SEQ PUTFH CLOSE
         ...
         SEQ PUTFH DELEGRETURN
   <CODE ENDS>

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   With the proposed approach of setting the
   OPEN_ARGS_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION flag during the OPEN,
   the number of operations is always 3.  The first two compounds are
   still synchronous, but the last is asynchronous.  I.e., since the
   client no longer has to send a CLOSE operation, it can delay the
   DELEGRETURN until either the server requests it back via delegation
   recall or garbage collection causes the client to return the stateid.

   <CODE BEGINS>
         SEQ PUTFH OPEN(OPEN_ARGS_SHARE_ACCESS_WANT_OPEN_XOR_DELEGATION)
             GETFH GETATTR
         SEQ PUTFH WRITE GETATTR
         ...
         SEQ PUTFH DELEGRETURN
   <CODE ENDS>

   This approach reduces the cost of synchronous operations by 33% and
   the total number of operations by 25%. Contrast that against the
   alternative proposal of having CLOSE return both stateids, which
   would not reduce the number of synchronous operations.

5.  Proxying of Times

   When a client is granted a write delegation on a file, it becomes the
   authority for the file contents and associated attributes.  If the
   server queries the client as to the state of the file via a
   CB_GETATTR (see Section 20.1 of [RFC8881]), then, according to the
   unextended NFSv4 protocol, it can only determine the size of the file
   and the change attribute.  In the case of the client holding the
   delegation, it has the current values of the access and modify times.
   There is no way that other clients can have access to these values.
   While the client could send a compound of the form: SEQ, PUTFH,
   SETATTR (time_modify | time_access), DELEGRETURN, to notify the
   server of the proxied values, that SETATTR (see Section 18.30 of
   [RFC8881]) operation would cause either or both of change (see
   Section 5.8.1.4 of [RFC8881]) or time_metadata (see Section 5.8.2.42
   of [RFC8881]) to be modified to the current time on the server.
   There is no current provision to obtain these values before
   delegation return using CB_GETATTR.  As a result, it can not pass
   these times up to an application expecting POSIX compliance, as is
   often necessary for correct operation.

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   With the addition of the new flag:
   OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS, the client and server can
   negotiate that the client will be the authority for these values and
   upon return of the delegation stateid via a DELEGRETURN (see section
   18.6 of [RFC8881]), the times will be passed back to the server.  If
   the server is queried by another client for either the size or the
   times, it will need to use a CB_GETATTR to query the client which
   holds the delegation (see Section 20.1 of [RFC8881]).

   If a server informs the client via the fattr4_open_arguments
   attribute that it supports
   OPEN_ARGS_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS and it returns a valid
   delegation stateid for an OPEN operation which sets the
   OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS flag, then it MUST query the
   client via a CB_GETATTR for the fattr4_time_deleg_access (see
   Section 5.2) attribute and fattr4_time_deleg_modify attribute (see
   Section 5.2).  (The change time can be derived from the modify time.)
   Further, when it gets a SETATTR with those attributes being set, then
   it MUST accept those fattr4_time_deleg_access attribute and
   fattr4_time_deleg_modify attribute changes and derive the change time
   or reject the changes with NFS4ERR_DELAY (see Section 15.1.1.3 of
   [RFC8881]).

   These new attributes are invalid to be used with GETATTR, VERIFY, and
   NVERIFY and can only be used with CB_GETATTR and SETATTR by a client
   holding an appropriate delegation.  The SETATTR SHOULD either be in a
   separate compound before the one containing the DELEGRETURN or when
   in the same compound, as an operation before the DELEGRETURN.
   Failure to properly sequence the operations may lead to race
   conditions.

   A key prerequisite of this approach is that the server and client are
   in time synchronization with each other.  Note that while the base
   NFSv4.2 does not require such synchronization, the use of RPCSEC_GSS
   typically makes such a requirement.  When the client presents either
   fattr4_time_deleg_access or fattr4_time_deleg_modify attributes to
   the server, the server MUST decide for both of them whether the time
   presented is before the corresponding time_access (see
   Section 5.8.2.37 of [RFC8881]) or time_modify (see Section 5.8.2.43
   of [RFC8881]) attribute on the file or past the current server time.
   When the time presented is before the original time, then the update
   is ignored.  When the time presented is in the future, the server can
   either clamp the new time to the current time, or it may return
   NFS4ERR_DELAY to the client, allowing it to retry.  Note that if the
   clock skew is large, the delay approach would result in access to the
   file being denied until the clock skew is exceeded.

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   A change in the access time MUST NOT advance the change time, also
   known as the time_metadata attribute (see Section 5.8.2.42 of
   [RFC8881]), but a change in the modify time might advance the change
   time (and in turn the change attribute (See Section 5.8.1.4 of
   [RFC8881]).  If the modify time is greater than the change time and
   before the current time, then the change time is adjusted to the
   modify time and not the current time (as is most likely done on most
   SETATTR calls that change the metadata).  If the modify time is in
   the future, it will be clamped to the current time.

   Note that each of the possible times, access, modify, and change, are
   compared to the current time.  They should all be compared against
   the same time value for the current time.  I.e., do not retrieve a
   different value of the current time for each calculation.

   If the client sets the OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS flag
   in an OPEN operation, then it MUST support the
   fattr4_time_deleg_access and fattr4_time_deleg_modify attributes both
   in the CB_GETATTR and SETATTR operations.

5.1.  Use case: NFSv3 client proxy

   Consider a NFSv3 client which wants to access data on a server which
   only supports NFSv4.2.  An implementation may introduce an NFSv3
   server that functions as an NFSv4.2 client, serving as a gateway
   between the two otherwise incompatible systems.  As NFSv3 is a
   stateless protocol, the state is not kept on the client, but rather
   the NFSv3 server.  As the NFSv3 server is already managing the state,
   it can proxy file delegations to avoid spurious GETATTRs.  I.e., as
   the client queries the NFSv3 server for the attributes, they can be
   served without the NFSv3 server sending a GETATTR to the NFSv4.2
   server.

5.2.  XDR for Proxying of Times

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   <CODE BEGINS>
   ///
   /// /*
   ///  * attributes for the delegation times being
   ///  * cached and served by the "client"
   ///  */
   /// typedef nfstime4        fattr4_time_deleg_access;
   /// typedef nfstime4        fattr4_time_deleg_modify;
   ///
   ///
   /// %/*
   /// % * New RECOMMENDED Attribute for
   /// % * delegation caching of times
   /// % */
   /// const FATTR4_TIME_DELEG_ACCESS  = 84;
   /// const FATTR4_TIME_DELEG_MODIFY  = 85;
   ///
   ///
   /// const OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS = 0x100000;
   ///
   <CODE ENDS>

6.  Extraction of XDR

   This document contains the external data representation (XDR)
   [RFC4506] description of the new open flags for delegating the file
   to the client.  The XDR description is embedded in this document in a
   way that makes it simple for the reader to extract into a ready-to-
   compile form.  The reader can feed this document into the following
   shell script to produce the machine readable XDR description of the
   new flags:

   <CODE BEGINS>
   #!/bin/sh
   grep '^ *///' $* | sed 's?^ */// ??' | sed 's?^ *///$??'
   <CODE ENDS>

   That is, if the above script is stored in a file called "extract.sh",
   and this document is in a file called "spec.txt", then the reader can
   do:

   <CODE BEGINS>
   sh extract.sh < spec.txt > delstid_prot.x
   <CODE ENDS>

   The effect of the script is to remove leading white space from each
   line, plus a sentinel sequence of "///".  XDR descriptions with the
   sentinel sequence are embedded throughout the document.

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   Note that the XDR code contained in this document depends on types
   from the NFSv4.2 nfs4_prot.x file (generated from [RFC7863]).  This
   includes both nfs types that end with a 4, such as offset4, length4,
   etc., as well as more generic types such as uint32_t and uint64_t.

   While the XDR can be appended to that from [RFC7863], the various
   code snippets belong in their respective areas of that XDR.

7.  Security Considerations

   While we are extending some capabilities for client delegation, there
   are no new security concerns.  The client cannot be queried by other
   clients as to the cached attributes.  The client could report false
   data for the cached attributes, but it already has this ability via a
   SETATTR operation (see Section 18.30 of [RFC8881]).

8.  IANA Considerations

   There are no IANA considerations.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4506]  Eisler, M., Ed., "XDR: External Data Representation
              Standard", STD 67, RFC 4506, DOI 10.17487/RFC4506, May
              2006, <https://www.rfc-editor.org/info/rfc4506>.

   [RFC7862]  Haynes, T., "Network File System (NFS) Version 4 Minor
              Version 2 Protocol", RFC 7862, DOI 10.17487/RFC7862,
              November 2016, <https://www.rfc-editor.org/info/rfc7862>.

   [RFC7863]  Haynes, T., "Network File System (NFS) Version 4 Minor
              Version 2 External Data Representation Standard (XDR)
              Description", RFC 7863, DOI 10.17487/RFC7863, November
              2016, <https://www.rfc-editor.org/info/rfc7863>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

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Internet-Draft                Deleg Stateid                 October 2024

   [RFC8178]  Noveck, D., "Rules for NFSv4 Extensions and Minor
              Versions", RFC 8178, DOI 10.17487/RFC8178, July 2017,
              <https://www.rfc-editor.org/info/rfc8178>.

   [RFC8881]  Noveck, D., Ed. and C. Lever, "Network File System (NFS)
              Version 4 Minor Version 1 Protocol", RFC 8881,
              DOI 10.17487/RFC8881, August 2020,
              <https://www.rfc-editor.org/info/rfc8881>.

Appendix A.  Acknowledgments

   Trond Myklebust, Tom Haynes, and David Flynn all worked on the
   prototype at Hammerspace.

   Dave Noveck, Chuck Lever, Rick Macklem, and Zaheduzzaman Sarker
   provided reviews of the document.

   Jeff Layton provided experience from an implementation he authored.

Authors' Addresses

   Thomas Haynes
   Hammerspace
   Email: loghyr@hammerspace.com

   Trond Myklebust
   Hammerspace
   Email: trondmy@hammerspace.com

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