NFSv4 T. Haynes, Ed.
Internet-Draft NetApp
Intended status: Standards Track August 13, 2013
Expires: February 14, 2014
NFS Version 4 Minor Version 2
draft-ietf-nfsv4-minorversion2-20.txt
Abstract
This Internet-Draft describes NFS version 4 minor version two,
focusing mainly on the protocol extensions made from NFS version 4
minor version 0 and NFS version 4 minor version 1. Major extensions
introduced in NFS version 4 minor version two include: Server-side
Copy, Application I/O Advise, Space Reservations, Sparse Files,
Application Data Blocks, and Labeled NFS.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 14, 2014.
Copyright Notice
Copyright (c) 2013 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
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publication of this document. Please review these documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. The NFS Version 4 Minor Version 2 Protocol . . . . . . . 5
1.2. Scope of This Document . . . . . . . . . . . . . . . . . 5
1.3. NFSv4.2 Goals . . . . . . . . . . . . . . . . . . . . . . 5
1.4. Overview of NFSv4.2 Features . . . . . . . . . . . . . . 6
1.4.1. Server-side Copy . . . . . . . . . . . . . . . . . . . 6
1.4.2. Application I/O Advise . . . . . . . . . . . . . . . . 6
1.4.3. Sparse Files . . . . . . . . . . . . . . . . . . . . . 6
1.4.4. Space Reservation . . . . . . . . . . . . . . . . . . 6
1.4.5. Application Data Hole (ADH) Support . . . . . . . . . 6
1.4.6. Labeled NFS . . . . . . . . . . . . . . . . . . . . . 6
1.5. Differences from NFSv4.1 . . . . . . . . . . . . . . . . 7
2. Minor Versioning . . . . . . . . . . . . . . . . . . . . . . . 7
3. Server-side Copy . . . . . . . . . . . . . . . . . . . . . . . 10
3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 11
3.2.1. Overview of Copy Operations . . . . . . . . . . . . . 11
3.2.2. Locking the Files . . . . . . . . . . . . . . . . . . 12
3.2.3. Intra-Server Copy . . . . . . . . . . . . . . . . . . 12
3.2.4. Inter-Server Copy . . . . . . . . . . . . . . . . . . 14
3.2.5. Server-to-Server Copy Protocol . . . . . . . . . . . . 18
3.3. Requirements for Operations . . . . . . . . . . . . . . . 19
3.3.1. netloc4 - Network Locations . . . . . . . . . . . . . 20
3.3.2. Copy Offload Stateids . . . . . . . . . . . . . . . . 20
3.4. Security Considerations . . . . . . . . . . . . . . . . . 21
3.4.1. Inter-Server Copy Security . . . . . . . . . . . . . . 21
4. Support for Application IO Hints . . . . . . . . . . . . . . . 23
5. Sparse Files . . . . . . . . . . . . . . . . . . . . . . . . . 24
5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 24
5.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 24
5.3. New Operations . . . . . . . . . . . . . . . . . . . . . 25
5.3.1. READ_PLUS . . . . . . . . . . . . . . . . . . . . . . 25
5.3.2. WRITE_PLUS . . . . . . . . . . . . . . . . . . . . . . 25
6. Space Reservation . . . . . . . . . . . . . . . . . . . . . . 26
6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 26
7. Application Data Hole Support . . . . . . . . . . . . . . . . 28
7.1. Generic Framework . . . . . . . . . . . . . . . . . . . . 29
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7.1.1. Data Hole Representation . . . . . . . . . . . . . . . 29
7.1.2. Data Content . . . . . . . . . . . . . . . . . . . . . 30
7.2. An Example of Detecting Corruption . . . . . . . . . . . 30
7.3. Example of READ_PLUS . . . . . . . . . . . . . . . . . . 31
8. Labeled NFS . . . . . . . . . . . . . . . . . . . . . . . . . 32
8.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 32
8.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 33
8.3. MAC Security Attribute . . . . . . . . . . . . . . . . . 34
8.3.1. Delegations . . . . . . . . . . . . . . . . . . . . . 34
8.3.2. Permission Checking . . . . . . . . . . . . . . . . . 35
8.3.3. Object Creation . . . . . . . . . . . . . . . . . . . 35
8.3.4. Existing Objects . . . . . . . . . . . . . . . . . . . 35
8.3.5. Label Changes . . . . . . . . . . . . . . . . . . . . 35
8.4. pNFS Considerations . . . . . . . . . . . . . . . . . . . 36
8.5. Discovery of Server Labeled NFS Support . . . . . . . . . 36
8.6. MAC Security NFS Modes of Operation . . . . . . . . . . . 36
8.6.1. Full Mode . . . . . . . . . . . . . . . . . . . . . . 36
8.6.2. Guest Mode . . . . . . . . . . . . . . . . . . . . . . 38
8.7. Security Considerations . . . . . . . . . . . . . . . . . 38
9. Sharing change attribute implementation details with NFSv4
clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 39
10. Security Considerations . . . . . . . . . . . . . . . . . . . 39
11. Error Values . . . . . . . . . . . . . . . . . . . . . . . . . 39
11.1. Error Definitions . . . . . . . . . . . . . . . . . . . . 40
11.1.1. General Errors . . . . . . . . . . . . . . . . . . . . 40
11.1.2. Server to Server Copy Errors . . . . . . . . . . . . . 40
11.1.3. Labeled NFS Errors . . . . . . . . . . . . . . . . . . 41
11.2. New Operations and Their Valid Errors . . . . . . . . . . 41
11.3. New Callback Operations and Their Valid Errors . . . . . 44
12. New File Attributes . . . . . . . . . . . . . . . . . . . . . 45
12.1. New RECOMMENDED Attributes - List and Definition
References . . . . . . . . . . . . . . . . . . . . . . . 45
12.2. Attribute Definitions . . . . . . . . . . . . . . . . . . 46
13. Operations: REQUIRED, RECOMMENDED, or OPTIONAL . . . . . . . . 49
14. NFSv4.2 Operations . . . . . . . . . . . . . . . . . . . . . . 53
14.1. Operation 59: COPY - Initiate a server-side copy . . . . 53
14.2. Operation 60: OFFLOAD_ABORT - Cancel a server-side
copy . . . . . . . . . . . . . . . . . . . . . . . . . . 56
14.3. Operation 61: COPY_NOTIFY - Notify a source server of
a future copy . . . . . . . . . . . . . . . . . . . . . . 57
14.4. Operation 62: OFFLOAD_REVOKE - Revoke a destination
server's copy privileges . . . . . . . . . . . . . . . . 58
14.5. Operation 63: OFFLOAD_STATUS - Poll for status of a
server-side copy . . . . . . . . . . . . . . . . . . . . 59
14.6. Modification to Operation 42: EXCHANGE_ID -
Instantiate Client ID . . . . . . . . . . . . . . . . . . 60
14.7. Operation 64: WRITE_PLUS . . . . . . . . . . . . . . . . 61
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14.8. Operation 67: IO_ADVISE - Application I/O access
pattern hints . . . . . . . . . . . . . . . . . . . . . . 67
14.9. Changes to Operation 51: LAYOUTRETURN . . . . . . . . . . 72
14.10. Operation 65: READ_PLUS . . . . . . . . . . . . . . . . . 75
14.11. Operation 66: SEEK . . . . . . . . . . . . . . . . . . . 80
15. NFSv4.2 Callback Operations . . . . . . . . . . . . . . . . . 81
15.1. Operation 15: CB_OFFLOAD - Report results of an
asynchronous operation . . . . . . . . . . . . . . . . . 81
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 82
17. References . . . . . . . . . . . . . . . . . . . . . . . . . . 83
17.1. Normative References . . . . . . . . . . . . . . . . . . 83
17.2. Informative References . . . . . . . . . . . . . . . . . 83
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 85
Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 85
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 86
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1. Introduction
1.1. The NFS Version 4 Minor Version 2 Protocol
The NFS version 4 minor version 2 (NFSv4.2) protocol is the third
minor version of the NFS version 4 (NFSv4) protocol. The first minor
version, NFSv4.0, is described in [I-D.ietf-nfsv4-rfc3530bis] and the
second minor version, NFSv4.1, is described in [RFC5661]. It follows
the guidelines for minor versioning that are listed in Section 11 of
[I-D.ietf-nfsv4-rfc3530bis].
As a minor version, NFSv4.2 is consistent with the overall goals for
NFSv4, but extends the protocol so as to better meet those goals,
based on experiences with NFSv4.1. In addition, NFSv4.2 has adopted
some additional goals, which motivate some of the major extensions in
NFSv4.2.
1.2. Scope of This Document
This document describes the NFSv4.2 protocol. With respect to
NFSv4.0 and NFSv4.1, this document does not:
o describe the NFSv4.0 or NFSv4.1 protocols, except where needed to
contrast with NFSv4.2
o modify the specification of the NFSv4.0 or NFSv4.1 protocols
o clarify the NFSv4.0 or NFSv4.1 protocols. I.e., any
clarifications made here apply to NFSv4.2 and neither of the prior
protocols
The full XDR for NFSv4.2 is presented in [4.2xdr].
1.3. NFSv4.2 Goals
The goal of the design of NFSv4.2 is to take common local file system
features and offer them remotely. These features might
o already be available on the servers, e.g., sparse files
o be under development as a new standard, e.g., SEEK_HOLE and
SEEK_DATA
o be used by clients with the servers via some proprietary means,
e.g., Labeled NFS
but the clients are not able to leverage them on the server within
the confines of the NFS protocol.
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1.4. Overview of NFSv4.2 Features
1.4.1. Server-side Copy
A traditional file copy from one server to another results in the
data being put on the network twice - source to client and then
client to destination. New operations are introduced to allow the
client to authorize the two servers to interact directly. As this
copy can be lengthy, asynchronous support is also provided.
1.4.2. Application I/O Advise
Applications and clients want to advise the server as to expected I/O
behavior. Using IO_ADVISE (see Section 14.8) to communicate future
I/O behavior such as whether a file will be accessed sequentially or
randomly, and whether a file will or will not be accessed in the near
future, allows servers to optimize future I/O requests for a file by,
for example, prefetching or evicting data. This operation can be
used to support the posix_fadvise function as well as other
applications such as databases and video editors.
1.4.3. Sparse Files
Sparse files are ones which have unallocated data blocks as holes in
the file. Such holes are typically transferred as 0s during I/O.
READ_PLUS (see Section 14.10) allows a server to send back to the
client metadata describing the hole and WRITE_PLUS (see Section 14.7)
allows the client to punch holes into a file. In addition, SEEK (see
Section 14.11) is provided to scan for the next hole or data from a
given location.
1.4.4. Space Reservation
When a file is sparse, one concern applications have is ensuring that
there will always be enough data blocks available for the file during
future writes. A new attribute, space_reserved (see Section 12.2.4)
provides the client a guarantee that space will be available.
1.4.5. Application Data Hole (ADH) Support
Some applications treat a file as if it were a disk and as such want
to initialize (or format) the file image. We extend both READ_PLUS
and WRITE_PLUS to understand this metadata as a new form of a hole.
1.4.6. Labeled NFS
While both clients and servers can employ Mandatory Access Control
(MAC) security models to enforce data access, there has been no
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protocol support to allow full interoperability. A new file object
attribute, sec_label (see Section 12.2.2) allows for the server to
store and enforce MAC labels. The format of the sec_label
accommodates any MAC security system.
1.5. Differences from NFSv4.1
In NFSv4.1, the only way to introduce new variants of an operation
was to introduce a new operation. I.e., READ becomes either READ2 or
READ_PLUS. With the use of discriminated unions as parameters to
such functions in NFSv4.2, it is possible to add a new arm in a
subsequent minor version. And it is also possible to move such an
operation from OPTIONAL/RECOMMENDED to REQUIRED. Forcing an
implementation to adopt each arm of a discriminated union at such a
time does not meet the spirit of the minor versioning rules. As
such, new arms of a discriminated union MUST follow the same
guidelines for minor versioning as operations in NFSv4.1 - i.e., they
may not be made REQUIRED. To support this, a new error code,
NFS4ERR_UNION_NOTSUPP, is introduced which allows the server to
communicate to the client that the operation is supported, but the
specific arm of the discriminated union is not.
2. Minor Versioning
To address the requirement of an NFS protocol that can evolve as the
need arises, the NFSv4 protocol contains the rules and framework to
allow for future minor changes or versioning.
The base assumption with respect to minor versioning is that any
future accepted minor version will be documented in one or more
Standards Track RFCs. Minor version 0 of the NFSv4 protocol is
represented by [I-D.ietf-nfsv4-rfc3530bis], minor version 1 by
[RFC5661], and minor version 2 by this document. The COMPOUND and
CB_COMPOUND procedures support the encoding of the minor version
being requested by the client.
The following items represent the basic rules for the development of
minor versions. Note that a future minor version may modify or add
to the following rules as part of the minor version definition.
1. Procedures are not added or deleted.
To maintain the general RPC model, NFSv4 minor versions will not
add to or delete procedures from the NFS program.
2. Minor versions may add operations to the COMPOUND and
CB_COMPOUND procedures.
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The addition of operations to the COMPOUND and CB_COMPOUND
procedures does not affect the RPC model.
* Minor versions may append attributes to the bitmap4 that
represents sets of attributes and to the fattr4 that
represents sets of attribute values.
This allows for the expansion of the attribute model to allow
for future growth or adaptation.
* Minor version X must append any new attributes after the last
documented attribute.
Since attribute results are specified as an opaque array of
per-attribute, XDR-encoded results, the complexity of adding
new attributes in the midst of the current definitions would
be too burdensome.
3. Minor versions must not modify the structure of an existing
operation's arguments or results.
Again, the complexity of handling multiple structure definitions
for a single operation is too burdensome. New operations should
be added instead of modifying existing structures for a minor
version.
This rule does not preclude the following adaptations in a minor
version:
* adding bits to flag fields, such as new attributes to
GETATTR's bitmap4 data type, and providing corresponding
variants of opaque arrays, such as a notify4 used together
with such bitmaps
* adding bits to existing attributes like ACLs that have flag
words
* extending enumerated types (including NFS4ERR_*) with new
values
* adding cases to a switched union
4. Note that when adding new cases to a switched union, a minor
version must not make new cases be REQUIRED. While the
encapsulating operation may be REQUIRED, the new cases (the
specific arm of the discriminated union) is not. The error code
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NFS4ERR_UNION_NOTSUPP is used to notify the client when the
server does not support such a case.
5. Minor versions must not modify the structure of existing
attributes.
6. Minor versions must not delete operations.
This prevents the potential reuse of a particular operation
"slot" in a future minor version.
7. Minor versions must not delete attributes.
8. Minor versions must not delete flag bits or enumeration values.
9. Minor versions may declare an operation MUST NOT be implemented.
Specifying that an operation MUST NOT be implemented is
equivalent to obsoleting an operation. For the client, it means
that the operation MUST NOT be sent to the server. For the
server, an NFS error can be returned as opposed to "dropping"
the request as an XDR decode error. This approach allows for
the obsolescence of an operation while maintaining its structure
so that a future minor version can reintroduce the operation.
1. Minor versions may declare that an attribute MUST NOT be
implemented.
2. Minor versions may declare that a flag bit or enumeration
value MUST NOT be implemented.
10. Minor versions may declare an operation to be OBSOLESCENT, which
indicates an intention to remove the operation (i.e., make it
MANDATORY TO NOT implement) in a subsequent minor version. Such
labeling is separate from the question of whether the operation
is REQUIRED or RECOMMENDED or OPTIONAL in the current minor
version. An operation may be both REQUIRED for the given minor
version and marked OBSOLESCENT, with the expectation that it
will be MANDATORY TO NOT implement in the next (or other
subsequent) minor version.
11. Note that the early notification of operation obsolescence is
put in place to mitigate the effects of design and
implementation mistakes, and to allow protocol development to
adapt to unexpected changes in the pace of implementation. Even
if an operation is marked OBSOLESCENT in a given minor version,
it may end up not being marked MANDATORY TO NOT implement in the
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next minor version. In unusual circumstances, it might not be
marked OBSOLESCENT in a subsequent minor version, and never
become MANDATORY TO NOT implement.
12. Minor versions may downgrade features from REQUIRED to
RECOMMENDED, from RECOMMENDED to OPTIONAL, or from OPTIONAL to
MANDATORY TO NOT implement. Also, if a feature was marked as
OBSOLESCENT in the prior minor version, it may be downgraded
from REQUIRED to OPTIONAL from RECOMMENDED to MANDATORY TO NOT
implement, or from REQUIRED to MANDATORY TO NOT implement.
13. Minor versions may upgrade features from OPTIONAL to
RECOMMENDED, or RECOMMENDED to REQUIRED. Also, if a feature was
marked as OBSOLESCENT in the prior minor version, it may be
upgraded to not be OBSOLESCENT.
14. A client and server that support minor version X SHOULD support
minor versions 0 through X-1 as well.
15. Except for infrastructural changes, a minor version must not
introduce REQUIRED new features.
This rule allows for the introduction of new functionality and
forces the use of implementation experience before designating a
feature as REQUIRED. On the other hand, some classes of
features are infrastructural and have broad effects. Allowing
infrastructural features to be RECOMMENDED or OPTIONAL
complicates implementation of the minor version.
16. A client MUST NOT attempt to use a stateid, filehandle, or
similar returned object from the COMPOUND procedure with minor
version X for another COMPOUND procedure with minor version Y,
where X != Y.
3. Server-side Copy
3.1. Introduction
The server-side copy feature provides a mechanism for the NFS client
to perform a file copy on the server without the data being
transmitted back and forth over the network. Without this feature,
an NFS client copies data from one location to another by reading the
data from the server over the network, and then writing the data back
over the network to the server. Using this server-side copy
operation, the client is able to instruct the server to copy the data
locally without the data being sent back and forth over the network
unnecessarily.
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If the source object and destination object are on different file
servers, the file servers will communicate with one another to
perform the copy operation. The server-to-server protocol by which
this is accomplished is not defined in this document.
3.2. Protocol Overview
The server-side copy offload operations support both intra-server and
inter-server file copies. An intra-server copy is a copy in which
the source file and destination file reside on the same server. In
an inter-server copy, the source file and destination file are on
different servers. In both cases, the copy may be performed
synchronously or asynchronously.
Throughout the rest of this document, we refer to the NFS server
containing the source file as the "source server" and the NFS server
to which the file is transferred as the "destination server". In the
case of an intra-server copy, the source server and destination
server are the same server. Therefore in the context of an intra-
server copy, the terms source server and destination server refer to
the single server performing the copy.
The operations described below are designed to copy files. Other
file system objects can be copied by building on these operations or
using other techniques. For example if the user wishes to copy a
directory, the client can synthesize a directory copy by first
creating the destination directory and then copying the source
directory's files to the new destination directory. If the user
wishes to copy a namespace junction [FEDFS-NSDB] [FEDFS-ADMIN], the
client can use the ONC RPC Federated Filesystem protocol
[FEDFS-ADMIN] to perform the copy. Specifically the client can
determine the source junction's attributes using the FEDFS_LOOKUP_FSN
procedure and create a duplicate junction using the
FEDFS_CREATE_JUNCTION procedure.
For the inter-server copy, the operations are defined to be
compatible with the traditional copy authentication approach. The
client and user are authorized at the source for reading. Then they
are authorized at the destination for writing.
3.2.1. Overview of Copy Operations
COPY_NOTIFY: For inter-server copies, the client sends this
operation to the source server to notify it of a future file copy
from a given destination server for the given user.
(Section 14.3)
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OFFLOAD_REVOKE: Also for inter-server copies, the client sends this
operation to the source server to revoke permission to copy a file
for the given user. (Section 14.4)
COPY: Used by the client to request a file copy. (Section 14.1)
OFFLOAD_ABORT: Used by the client to abort an asynchronous file
copy. (Section 14.2)
OFFLOAD_STATUS: Used by the client to poll the status of an
asynchronous file copy. (Section 14.5)
CB_OFFLOAD: Used by the destination server to report the results of
an asynchronous file copy to the client. (Section 15.1)
3.2.2. Locking the Files
Both the source and destination file may need to be locked to protect
the content during the copy operations. A client can achieve this by
a combination of OPEN and LOCK operations. I.e., either share or
byte range locks might be desired.
3.2.3. Intra-Server Copy
To copy a file on a single server, the client uses a COPY operation.
The server may respond to the copy operation with the final results
of the copy or it may perform the copy asynchronously and deliver the
results using a CB_OFFLOAD operation callback. If the copy is
performed asynchronously, the client may poll the status of the copy
using OFFLOAD_STATUS or cancel the copy using OFFLOAD_ABORT.
A synchronous intra-server copy is shown in Figure 1. In this
example, the NFS server chooses to perform the copy synchronously.
The copy operation is completed, either successfully or
unsuccessfully, before the server replies to the client's request.
The server's reply contains the final result of the operation.
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Client Server
+ +
| |
|--- OPEN ---------------------------->| Client opens
|<------------------------------------/| the source file
| |
|--- OPEN ---------------------------->| Client opens
|<------------------------------------/| the destination file
| |
|--- COPY ---------------------------->| Client requests
|<------------------------------------/| a file copy
| |
|--- CLOSE --------------------------->| Client closes
|<------------------------------------/| the destination file
| |
|--- CLOSE --------------------------->| Client closes
|<------------------------------------/| the source file
| |
| |
Figure 1: A synchronous intra-server copy.
An asynchronous intra-server copy is shown in Figure 2. In this
example, the NFS server performs the copy asynchronously. The
server's reply to the copy request indicates that the copy operation
was initiated and the final result will be delivered at a later time.
The server's reply also contains a copy stateid. The client may use
this copy stateid to poll for status information (as shown) or to
cancel the copy using a OFFLOAD_ABORT. When the server completes the
copy, the server performs a callback to the client and reports the
results.
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Client Server
+ +
| |
|--- OPEN ---------------------------->| Client opens
|<------------------------------------/| the source file
| |
|--- OPEN ---------------------------->| Client opens
|<------------------------------------/| the destination file
| |
|--- COPY ---------------------------->| Client requests
|<------------------------------------/| a file copy
| |
| |
|--- OFFLOAD_STATUS ------------------>| Client may poll
|<------------------------------------/| for status
| |
| . | Multiple OFFLOAD_STATUS
| . | operations may be sent.
| . |
| |
|<-- CB_OFFLOAD -----------------------| Server reports results
|\------------------------------------>|
| |
|--- CLOSE --------------------------->| Client closes
|<------------------------------------/| the destination file
| |
|--- CLOSE --------------------------->| Client closes
|<------------------------------------/| the source file
| |
| |
Figure 2: An asynchronous intra-server copy.
3.2.4. Inter-Server Copy
A copy may also be performed between two servers. The copy protocol
is designed to accommodate a variety of network topologies. As shown
in Figure 3, the client and servers may be connected by multiple
networks. In particular, the servers may be connected by a
specialized, high speed network (network 192.0.2.0/24 in the diagram)
that does not include the client. The protocol allows the client to
setup the copy between the servers (over network 203.0.113.0/24 in
the diagram) and for the servers to communicate on the high speed
network if they choose to do so.
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192.0.2.0/24
+-------------------------------------+
| |
| |
| 192.0.2.18 | 192.0.2.56
+-------+------+ +------+------+
| Source | | Destination |
+-------+------+ +------+------+
| 203.0.113.18 | 203.0.113.56
| |
| |
| 203.0.113.0/24 |
+------------------+------------------+
|
|
| 203.0.113.243
+-----+-----+
| Client |
+-----------+
Figure 3: An example inter-server network topology.
For an inter-server copy, the client notifies the source server that
a file will be copied by the destination server using a COPY_NOTIFY
operation. The client then initiates the copy by sending the COPY
operation to the destination server. The destination server may
perform the copy synchronously or asynchronously.
A synchronous inter-server copy is shown in Figure 4. In this case,
the destination server chooses to perform the copy before responding
to the client's COPY request.
An asynchronous copy is shown in Figure 5. In this case, the
destination server chooses to respond to the client's COPY request
immediately and then perform the copy asynchronously.
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Client Source Destination
+ + +
| | |
|--- OPEN --->| | Returns os1
|<------------------/| |
| | |
|--- COPY_NOTIFY --->| |
|<------------------/| |
| | |
|--- OPEN ---------------------------->| Returns os2
|<------------------------------------/|
| | |
|--- COPY ---------------------------->|
| | |
| | |
| |<----- read -----|
| |\--------------->|
| | |
| | . | Multiple reads may
| | . | be necessary
| | . |
| | |
| | |
|<------------------------------------/| Destination replies
| | | to COPY
| | |
|--- CLOSE --------------------------->| Release open state
|<------------------------------------/|
| | |
|--- CLOSE --->| | Release open state
|<------------------/| |
Figure 4: A synchronous inter-server copy.
Client Source Destination
+ + +
| | |
|--- OPEN --->| | Returns os1
|<------------------/| |
| | |
|--- LOCK --->| | Optional, could be done
|<------------------/| | with a share lock
| | |
|--- COPY_NOTIFY --->| | Need to pass in
|<------------------/| | os1 or lock state
| | |
| | |
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| | |
|--- OPEN ---------------------------->| Returns os2
|<------------------------------------/|
| | |
|--- LOCK ---------------------------->| Optional ...
|<------------------------------------/|
| | |
|--- COPY ---------------------------->| Need to pass in
|<------------------------------------/| os2 or lock state
| | |
| | |
| |<----- read -----|
| |\--------------->|
| | |
| | . | Multiple reads may
| | . | be necessary
| | . |
| | |
| | |
|--- OFFLOAD_STATUS ------------------>| Client may poll
|<------------------------------------/| for status
| | |
| | . | Multiple OFFLOAD_STATUS
| | . | operations may be sent
| | . |
| | |
| | |
| | |
|<-- CB_OFFLOAD -----------------------| Destination reports
|\------------------------------------>| results
| | |
|--- LOCKU --------------------------->| Only if LOCK was done
|<------------------------------------/|
| | |
|--- CLOSE --------------------------->| Release open state
|<------------------------------------/|
| | |
|--- LOCKU --->| | Only if LOCK was done
|<------------------/| |
| | |
|--- CLOSE --->| | Release open state
|<------------------/| |
| | |
Figure 5: An asynchronous inter-server copy.
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3.2.5. Server-to-Server Copy Protocol
The source server and destination server are not required to use a
specific protocol to transfer the file data. The choice of what
protocol to use is ultimately the destination server's decision.
3.2.5.1. Using NFSv4.x as a Server-to-Server Copy Protocol
The destination server MAY use standard NFSv4.x (where x >= 1)
operations to read the data from the source server. If NFSv4.x is
used for the server-to-server copy protocol, the destination server
can use the source filehandle provided in the COPY request with
standard NFSv4.x operations to read data from the source server.
Specifically, the destination server may use the NFSv4.x OPEN
operation's CLAIM_FH facility to open the file being copied and
obtain an open stateid. Using the stateid, the destination server
may then use NFSv4.x READ operations to read the file.
3.2.5.2. Using an alternative Server-to-Server Copy Protocol
In a homogeneous environment, the source and destination servers
might be able to perform the file copy extremely efficiently using
specialized protocols. For example the source and destination
servers might be two nodes sharing a common file system format for
the source and destination file systems. Thus the source and
destination are in an ideal position to efficiently render the image
of the source file to the destination file by replicating the file
system formats at the block level. Another possibility is that the
source and destination might be two nodes sharing a common storage
area network, and thus there is no need to copy any data at all, and
instead ownership of the file and its contents might simply be re-
assigned to the destination. To allow for these possibilities, the
destination server is allowed to use a server-to-server copy protocol
of its choice.
In a heterogeneous environment, using a protocol other than NFSv4.x
(e.g., HTTP [RFC2616] or FTP [RFC0959]) presents some challenges. In
particular, the destination server is presented with the challenge of
accessing the source file given only an NFSv4.x filehandle.
One option for protocols that identify source files with path names
is to use an ASCII hexadecimal representation of the source
filehandle as the file name.
Another option for the source server is to use URLs to direct the
destination server to a specialized service. For example, the
response to COPY_NOTIFY could include the URL
ftp://s1.example.com:9999/_FH/0x12345, where 0x12345 is the ASCII
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hexadecimal representation of the source filehandle. When the
destination server receives the source server's URL, it would use
"_FH/0x12345" as the file name to pass to the FTP server listening on
port 9999 of s1.example.com. On port 9999 there would be a special
instance of the FTP service that understands how to convert NFS
filehandles to an open file descriptor (in many operating systems,
this would require a new system call, one which is the inverse of the
makefh() function that the pre-NFSv4 MOUNT service needs).
Authenticating and identifying the destination server to the source
server is also a challenge. Recommendations for how to accomplish
this are given in Section 3.4.1.3.
3.3. Requirements for Operations
The implementation of server-side copy is OPTIONAL by the client and
the server. However, in order to successfully copy a file, some
operations MUST be supported by the client and/or server.
If a client desires an intra-server file copy, then it MUST support
the COPY and CB_OFFLOAD operations. If COPY returns a stateid, then
the client MAY use the OFFLOAD_ABORT and OFFLOAD_STATUS operations.
If a client desires an inter-server file copy, then it MUST support
the COPY, COPY_NOTICE, and CB_OFFLOAD operations, and MAY use the
OFFLOAD_REVOKE operation. If COPY returns a stateid, then the client
MAY use the OFFLOAD_ABORT and OFFLOAD_STATUS operations.
If a server supports intra-server copy, then the server MUST support
the COPY operation. If a server's COPY operation returns a stateid,
then the server MUST also support these operations: CB_OFFLOAD,
OFFLOAD_ABORT, and OFFLOAD_STATUS.
If a source server supports inter-server copy, then the source server
MUST support all these operations: COPY_NOTIFY and OFFLOAD_REVOKE.
If a destination server supports inter-server copy, then the
destination server MUST support the COPY operation. If a destination
server's COPY operation returns a stateid, then the destination
server MUST also support these operations: CB_OFFLOAD, OFFLOAD_ABORT,
COPY_NOTIFY, OFFLOAD_REVOKE, and OFFLOAD_STATUS.
Each operation is performed in the context of the user identified by
the ONC RPC credential of its containing COMPOUND or CB_COMPOUND
request. For example, a OFFLOAD_ABORT operation issued by a given
user indicates that a specified COPY operation initiated by the same
user be canceled. Therefore a OFFLOAD_ABORT MUST NOT interfere with
a copy of the same file initiated by another user.
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An NFS server MAY allow an administrative user to monitor or cancel
copy operations using an implementation specific interface.
3.3.1. netloc4 - Network Locations
The server-side copy operations specify network locations using the
netloc4 data type shown below:
enum netloc_type4 {
NL4_NAME = 0,
NL4_URL = 1,
NL4_NETADDR = 2
};
union netloc4 switch (netloc_type4 nl_type) {
case NL4_NAME: utf8str_cis nl_name;
case NL4_URL: utf8str_cis nl_url;
case NL4_NETADDR: netaddr4 nl_addr;
};
If the netloc4 is of type NL4_NAME, the nl_name field MUST be
specified as a UTF-8 string. The nl_name is expected to be resolved
to a network address via DNS, LDAP, NIS, /etc/hosts, or some other
means. If the netloc4 is of type NL4_URL, a server URL [RFC3986]
appropriate for the server-to-server copy operation is specified as a
UTF-8 string. If the netloc4 is of type NL4_NETADDR, the nl_addr
field MUST contain a valid netaddr4 as defined in Section 3.3.9 of
[RFC5661].
When netloc4 values are used for an inter-server copy as shown in
Figure 3, their values may be evaluated on the source server,
destination server, and client. The network environment in which
these systems operate should be configured so that the netloc4 values
are interpreted as intended on each system.
3.3.2. Copy Offload Stateids
A server may perform a copy offload operation asynchronously. An
asynchronous copy is tracked using a copy offload stateid. Copy
offload stateids are included in the COPY, OFFLOAD_ABORT,
OFFLOAD_STATUS, and CB_OFFLOAD operations.
Section 8.2.4 of [RFC5661] specifies that stateids are valid until
either (A) the client or server restart or (B) the client returns the
resource.
A copy offload stateid will be valid until either (A) the client or
server restarts or (B) the client returns the resource by issuing a
OFFLOAD_ABORT operation or the client replies to a CB_OFFLOAD
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operation.
A copy offload stateid's seqid MUST NOT be 0. In the context of a
copy offload operation, it is ambiguous to indicate the most recent
copy offload operation using a stateid with seqid of 0. Therefore a
copy offload stateid with seqid of 0 MUST be considered invalid.
3.4. Security Considerations
The security considerations pertaining to NFSv4
[I-D.ietf-nfsv4-rfc3530bis] apply to this chapter.
The standard security mechanisms provide by NFSv4
[I-D.ietf-nfsv4-rfc3530bis] may be used to secure the protocol
described in this chapter.
NFSv4 clients and servers supporting the inter-server copy operations
described in this chapter are REQUIRED to implement the mechanism
described in Section 3.4.1.2, and to support rejecting COPY_NOTIFY
requests that do not use RPCSEC_GSS with privacy. This requirement
to implement is not a requirement to use; for example, a server may
depending on configuration also allow COPY_NOTIFY requests that use
only AUTH_SYS.
3.4.1. Inter-Server Copy Security
3.4.1.1. Requirements for Secure Inter-Server Copy
Inter-server copy is driven by several requirements:
o The specification must not mandate an inter-server copy protocol.
There are many ways to copy data. Some will be more optimal than
others depending on the identities of the source server and
destination server. For example the source and destination
servers might be two nodes sharing a common file system format for
the source and destination file systems. Thus the source and
destination are in an ideal position to efficiently render the
image of the source file to the destination file by replicating
the file system formats at the block level. In other cases, the
source and destination might be two nodes sharing a common storage
area network, and thus there is no need to copy any data at all,
and instead ownership of the file and its contents simply gets re-
assigned to the destination.
o The specification must provide guidance for using NFSv4.x as a
copy protocol. For those source and destination servers willing
to use NFSv4.x there are specific security considerations that
this specification can and does address.
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o The specification must not mandate pre-configuration between the
source and destination server. Requiring that the source and
destination first have a "copying relationship" increases the
administrative burden. However the specification MUST NOT
preclude implementations that require pre-configuration.
o The specification must not mandate a trust relationship between
the source and destination server. The NFSv4 security model
requires mutual authentication between a principal on an NFS
client and a principal on an NFS server. This model MUST continue
with the introduction of COPY.
3.4.1.2. Inter-Server Copy via ONC RPC
In the absence of a strong security mechanism designed for the
purpose, the challenge is how the source server and destination
server identify themselves to each other, especially in the presence
of multi-homed source and destination servers. In a multi-homed
environment, the destination server might not contact the source
server from the same network address specified by the client in the
COPY_NOTIFY. This can be overcome using the procedure described
below.
When the client sends the source server the COPY_NOTIFY operation,
the source server may reply to the client with a list of target
addresses, names, and/or URLs and assign them to the unique
quadruple: <random number, source fh, user ID, destination address
Y>. If the destination uses one of these target netlocs to contact
the source server, the source server will be able to uniquely
identify the destination server, even if the destination server does
not connect from the address specified by the client in COPY_NOTIFY.
The level of assurance in this identification depends on the
unpredictability, strength and secrecy of the random number.
For example, suppose the network topology is as shown in Figure 3.
If the source filehandle is 0x12345, the source server may respond to
a COPY_NOTIFY for destination 203.0.113.56 with the URLs:
nfs://203.0.113.18//_COPY/FvhH1OKbu8VrxvV1erdjvR7N/203.0.113.56/
_FH/0x12345
nfs://192.0.2.18//_COPY/FvhH1OKbu8VrxvV1erdjvR7N/203.0.113.56/_FH/
0x12345
The name component after _COPY is 24 characters of base 64, more than
enough to encode a 128 bit random number.
The client will then send these URLs to the destination server in the
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COPY operation. Suppose that the 192.0.2.0/24 network is a high
speed network and the destination server decides to transfer the file
over this network. If the destination contacts the source server
from 192.0.2.56 over this network using NFSv4.1, it does the
following:
COMPOUND { PUTROOTFH, LOOKUP "_COPY" ; LOOKUP
"FvhH1OKbu8VrxvV1erdjvR7N" ; LOOKUP "203.0.113.56"; LOOKUP "_FH" ;
OPEN "0x12345" ; GETFH }
Provided that the random number is unpredictable and has been kept
secret by the parties involved, the source server will therefore know
that these NFSv4.x operations are being issued by the destination
server identified in the COPY_NOTIFY. This random number technique
only provides initial authentication of the destination server, and
cannot defend against man-in-the-middle attacks after authentication
or an eavesdropper that observes the random number on the wire.
Other secure communication techniques (e.g., IPsec) are necessary to
block these attacks.
Servers SHOULD reject COPY_NOTIFY requests that do not use RPCSEC_GSS
with privacy, thus ensuring the URL in the COPY_NOTIFY reply is
encrypted. For the same reason, clients SHOULD send COPY requests to
the destination using RPCSEC_GSS with privacy.
3.4.1.3. Inter-Server Copy without ONC RPC
The same techniques as Section 3.4.1.2, using unique URLs for each
destination server, can be used for other protocols (e.g., HTTP
[RFC2616] and FTP [RFC0959]) as well.
4. Support for Application IO Hints
Applications can issue client I/O hints via posix_fadvise()
[posix_fadvise] to the NFS client. While this can help the NFS
client optimize I/O and caching for a file, it does not allow the NFS
server and its exported file system to do likewise. We add an
IO_ADVISE procedure (Section 14.8) to communicate the client file
access patterns to the NFS server. The NFS server upon receiving a
IO_ADVISE operation MAY choose to alter its I/O and caching behavior,
but is under no obligation to do so.
Application specific NFS clients such as those used by hypervisors
and databases can also leverage application hints to communicate
their specialized requirements.
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5. Sparse Files
5.1. Introduction
A sparse file is a common way of representing a large file without
having to utilize all of the disk space for it. Consequently, a
sparse file uses less physical space than its size indicates. This
means the file contains 'holes', byte ranges within the file that
contain no data. Most modern file systems support sparse files,
including most UNIX file systems and NTFS, but notably not Apple's
HFS+. Common examples of sparse files include Virtual Machine (VM)
OS/disk images, database files, log files, and even checkpoint
recovery files most commonly used by the HPC community.
If an application reads a hole in a sparse file, the file system must
return all zeros to the application. For local data access there is
little penalty, but with NFS these zeroes must be transferred back to
the client. If an application uses the NFS client to read data into
memory, this wastes time and bandwidth as the application waits for
the zeroes to be transferred.
A sparse file is typically created by initializing the file to be all
zeros - nothing is written to the data in the file, instead the hole
is recorded in the metadata for the file. So a 8G disk image might
be represented initially by a couple hundred bits in the inode and
nothing on the disk. If the VM then writes 100M to a file in the
middle of the image, there would now be two holes represented in the
metadata and 100M in the data.
Two new operations WRITE_PLUS (Section 14.7) and READ_PLUS
(Section 14.10) are introduced. WRITE_PLUS allows for the creation
of a sparse file and for hole punching. An application might want to
zero out a range of the file. READ_PLUS supports all the features of
READ but includes an extension to support sparse pattern files
(Section 7.1.2). READ_PLUS is guaranteed to perform no worse than
READ, and can dramatically improve performance with sparse files.
READ_PLUS does not depend on pNFS protocol features, but can be used
by pNFS to support sparse files.
5.2. Terminology
Regular file: An object of file type NF4REG or NF4NAMEDATTR.
Sparse file: A Regular file that contains one or more Holes.
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Hole: A byte range within a Sparse file that contains regions of all
zeroes. For block-based file systems, this could also be an
unallocated region of the file.
Hole Threshold: The minimum length of a Hole as determined by the
server. If a server chooses to define a Hole Threshold, then it
would not return hole information about holes with a length
shorter than the Hole Threshold.
5.3. New Operations
READ_PLUS and WRITE_PLUS are new variants of the NFSv4.1 READ and
WRITE operations [RFC5661]. Besides being able to support all of the
data semantics of those operations, they can also be used by the
client and server to efficiently transfer both holes and ADHs (see
Section 7.1.1). As both READ and WRITE are inefficient for transfer
of sparse sections of the file, they are marked as OBSOLESCENT in
NFSv4.2. Instead, a client should utilize READ_PLUS and WRITE_PLUS.
Note that as the client has no a priori knowledge of whether either
an ADH or a hole is present or not, if it supports these operations
and so does the server, then it should always use these operations.
5.3.1. READ_PLUS
For holes, READ_PLUS extends the response to avoid returning data for
portions of the file which are initialized and contain no backing
store. Additionally it will do so if the result would appear to be a
hole. I.e., if the result was a data block composed entirely of
zeros, then it is easier to return a hole. Returning data blocks of
uninitialized data wastes computational and network resources, thus
reducing performance. For ADHs, READ_PLUS is used to return the
metadata describing the portions of the file which are initialized
and contain no backing store.
If the client sends a READ operation, it is explicitly stating that
it is neither supporting sparse files nor ADHs. So if a READ occurs
on a sparse ADH or file, then the server must expand such data to be
raw bytes. If a READ occurs in the middle of a hole or ADH, the
server can only send back bytes starting from that offset. In
contrast, if a READ_PLUS occurs in the middle of a hole or ADH, the
server can send back a range which starts before the offset and
extends past the range.
5.3.2. WRITE_PLUS
WRITE_PLUS can be used to either hole punch or initialize ADHs. For
either purpose, the client can avoid the transfer of a repetitive
pattern across the network. If the filesystem on the server does not
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supports sparse files, the WRITE_PLUS operation may return the result
asynchronously via the CB_OFFLOAD operation. As a hole punch may
entail deallocating data blocks, even if the filesystem supports
sparse files, it may still have to return the result via CB_OFFLOAD.
6. Space Reservation
6.1. Introduction
Applications such as hypervisors want to be able to reserve space for
a file, report the amount of actual disk space a file occupies, and
free-up the backing space of a file when it is not required. In
virtualized environments, virtual disk files are often stored on NFS
mounted volumes. Since virtual disk files represent the hard disks
of virtual machines, hypervisors often have to guarantee certain
properties for the file.
One such example is space reservation. When a hypervisor creates a
virtual disk file, it often tries to preallocate the space for the
file so that there are no future allocation related errors during the
operation of the virtual machine. Such errors prevent a virtual
machine from continuing execution and result in downtime.
Currently, in order to achieve such a guarantee, applications zero
the entire file. The initial zeroing allocates the backing blocks
and all subsequent writes are overwrites of already allocated blocks.
This approach is not only inefficient in terms of the amount of I/O
done, it is also not guaranteed to work on file systems that are log
structured or deduplicated. An efficient way of guaranteeing space
reservation would be beneficial to such applications.
We define a "reservation" as being the combination of the
space_reserved attribute (see Section 12.2.4) and the size attribute
(see Section 5.8.1.5 of [RFC5661]). If space_reserved attribute is
set on a file, it is guaranteed that writes that do not grow the file
past the size will not fail with NFS4ERR_NOSPC. Once the size is
changed, then the reservation is changed to that new size.
Another useful feature is the ability to report the number of blocks
that would be freed when a file is deleted. Currently, NFS reports
two size attributes:
size The logical file size of the file.
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space_used The size in bytes that the file occupies on disk
While these attributes are sufficient for space accounting in
traditional file systems, they prove to be inadequate in modern file
systems that support block sharing. In such file systems, multiple
inodes can point to a single block with a block reference count to
guard against premature freeing. Having a way to tell the number of
blocks that would be freed if the file was deleted would be useful to
applications that wish to migrate files when a volume is low on
space.
Since virtual disks represent a hard drive in a virtual machine, a
virtual disk can be viewed as a file system within a file. Since not
all blocks within a file system are in use, there is an opportunity
to reclaim blocks that are no longer in use. A call to deallocate
blocks could result in better space efficiency. Lesser space MAY be
consumed for backups after block deallocation.
The following operations and attributes can be used to resolve this
issues:
space_reserved This attribute specifies that writes to the reserved
area of the file will not fail with NFS4ERR_NOSPACE.
space_freed This attribute specifies the space freed when a file is
deleted, taking block sharing into consideration.
WRITE_PLUS This operation zeroes and/or deallocates the blocks
backing a region of the file.
If space_used of a file is interpreted to mean the size in bytes of
all disk blocks pointed to by the inode of the file, then shared
blocks get double counted, over-reporting the space utilization.
This also has the adverse effect that the deletion of a file with
shared blocks frees up less than space_used bytes.
On the other hand, if space_used is interpreted to mean the size in
bytes of those disk blocks unique to the inode of the file, then
shared blocks are not counted in any file, resulting in under-
reporting of the space utilization.
For example, two files A and B have 10 blocks each. Let 6 of these
blocks be shared between them. Thus, the combined space utilized by
the two files is 14 * BLOCK_SIZE bytes. In the former case, the
combined space utilization of the two files would be reported as 20 *
BLOCK_SIZE. However, deleting either would only result in 4 *
BLOCK_SIZE being freed. Conversely, the latter interpretation would
report that the space utilization is only 8 * BLOCK_SIZE.
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Adding another size attribute, space_freed (see Section 12.2.5), is
helpful in solving this problem. space_freed is the number of blocks
that are allocated to the given file that would be freed on its
deletion. In the example, both A and B would report space_freed as 4
* BLOCK_SIZE and space_used as 10 * BLOCK_SIZE. If A is deleted, B
will report space_freed as 10 * BLOCK_SIZE as the deletion of B would
result in the deallocation of all 10 blocks.
The addition of this problem does not solve the problem of space
being over-reported. However, over-reporting is better than under-
reporting.
7. Application Data Hole Support
At the OS level, files are contained on disk blocks. Applications
are also free to impose structure on the data contained in a file and
we can define an Application Data Block (ADB) to be such a structure.
From the application's viewpoint, it only wants to handle ADBs and
not raw bytes (see [Strohm11]). An ADB is typically comprised of two
sections: a header and data. The header describes the
characteristics of the block and can provide a means to detect
corruption in the data payload. The data section is typically
initialized to all zeros.
The format of the header is application specific, but there are two
main components typically encountered:
1. A logical block number which allows the application to determine
which data block is being referenced. This is useful when the
client is not storing the blocks in contiguous memory.
2. Fields to describe the state of the ADB and a means to detect
block corruption. For both pieces of data, a useful property is
that allowed values be unique in that if passed across the
network, corruption due to translation between big and little
endian architectures are detectable. For example, 0xF0DEDEF0 has
the same bit pattern in both architectures.
Applications already impose structures on files [Strohm11] and detect
corruption in data blocks [Ashdown08]. What they are not able to do
is efficiently transfer and store ADBs. To initialize a file with
ADBs, the client must send the full ADB to the server and that must
be stored on the server.
In this section, we are going to define an Application Data Hole
(ADH), which is a generic framework for transferring the ADB, present
one approach to detecting corruption in a given ADH implementation,
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and describe the model for how the client and server can support
efficient initialization of ADHs, reading of ADH holes, punching ADH
holes in a file, and space reservation. We define the ADHN to be the
Application Data Hole Number, which is the logical block number
discussed earlier.
7.1. Generic Framework
We want the representation of the ADH to be flexible enough to
support many different applications. The most basic approach is no
imposition of a block at all, which means we are working with the raw
bytes. Such an approach would be useful for storing holes, punching
holes, etc. In more complex deployments, a server might be
supporting multiple applications, each with their own definition of
the ADH. One might store the ADHN at the start of the block and then
have a guard pattern to detect corruption [McDougall07]. The next
might store the ADHN at an offset of 100 bytes within the block and
have no guard pattern at all, i.e., existing applications might
already have well defined formats for their data blocks.
The guard pattern can be used to represent the state of the block, to
protect against corruption, or both. Again, it needs to be able to
be placed anywhere within the ADH.
We need to be able to represent the starting offset of the block and
the size of the block. Note that nothing prevents the application
from defining different sized blocks in a file.
7.1.1. Data Hole Representation
struct app_data_hole4 {
offset4 adh_offset;
length4 adh_block_size;
length4 adh_block_count;
length4 adh_reloff_blocknum;
count4 adh_block_num;
length4 adh_reloff_pattern;
opaque adh_pattern<>;
};
The app_data_hole4 structure captures the abstraction presented for
the ADH. The additional fields present are to allow the transmission
of adh_block_count ADHs at one time. We also use adh_block_num to
convey the ADHN of the first block in the sequence. Each ADH will
contain the same adh_pattern string.
As both adh_block_num and adh_pattern are optional, if either
adh_reloff_pattern or adh_reloff_blocknum is set to NFS4_UINT64_MAX,
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then the corresponding field is not set in any of the ADH.
7.1.2. Data Content
/*
* Use an enum such that we can extend new types.
*/
enum data_content4 {
NFS4_CONTENT_DATA = 0,
NFS4_CONTENT_APP_DATA_HOLE = 1,
NFS4_CONTENT_HOLE = 2
};
New operations might need to differentiate between wanting to access
data versus an ADH. Also, future minor versions might want to
introduce new data formats. This enumeration allows that to occur.
7.2. An Example of Detecting Corruption
In this section, we define an ADH format in which corruption can be
detected. Note that this is just one possible format and means to
detect corruption.
Consider a very basic implementation of an operating system's disk
blocks. A block is either data or it is an indirect block which
allows for files to be larger than one block. It is desired to be
able to initialize a block. Lastly, to quickly unlink a file, a
block can be marked invalid. The contents remain intact - which
would enable this OS application to undelete a file.
The application defines 4k sized data blocks, with an 8 byte block
counter occurring at offset 0 in the block, and with the guard
pattern occurring at offset 8 inside the block. Furthermore, the
guard pattern can take one of four states:
0xfeedface - This is the FREE state and indicates that the ADH
format has been applied.
0xcafedead - This is the DATA state and indicates that real data
has been written to this block.
0xe4e5c001 - This is the INDIRECT state and indicates that the
block contains block counter numbers that are chained off of this
block.
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0xba1ed4a3 - This is the INVALID state and indicates that the block
contains data whose contents are garbage.
Finally, it also defines an 8 byte checksum [Baira08] starting at
byte 16 which applies to the remaining contents of the block. If the
state is FREE, then that checksum is trivially zero. As such, the
application has no need to transfer the checksum implicitly inside
the ADH - it need not make the transfer layer aware of the fact that
there is a checksum (see [Ashdown08] for an example of checksums used
to detect corruption in application data blocks).
Corruption in each ADH can thus be detected:
o If the guard pattern is anything other than one of the allowed
values, including all zeros.
o If the guard pattern is FREE and any other byte in the remainder
of the ADH is anything other than zero.
o If the guard pattern is anything other than FREE, then if the
stored checksum does not match the computed checksum.
o If the guard pattern is INDIRECT and one of the stored indirect
block numbers has a value greater than the number of ADHs in the
file.
o If the guard pattern is INDIRECT and one of the stored indirect
block numbers is a duplicate of another stored indirect block
number.
As can be seen, the application can detect errors based on the
combination of the guard pattern state and the checksum. But also,
the application can detect corruption based on the state and the
contents of the ADH. This last point is important in validating the
minimum amount of data we incorporated into our generic framework.
I.e., the guard pattern is sufficient in allowing applications to
design their own corruption detection.
Finally, it is important to note that none of these corruption checks
occur in the transport layer. The server and client components are
totally unaware of the file format and might report everything as
being transferred correctly even in the case the application detects
corruption.
7.3. Example of READ_PLUS
The hypothetical application presented in Section 7.2 can be used to
illustrate how READ_PLUS would return an array of results. A file is
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created and initialized with 100 4k ADHs in the FREE state:
WRITE_PLUS {0, 4k, 100, 0, 0, 8, 0xfeedface}
Further, assume the application writes a single ADH at 16k, changing
the guard pattern to 0xcafedead, we would then have in memory:
0 -> (16k - 1) : 4k, 4, 0, 0, 8, 0xfeedface
16k -> (20k - 1) : 00 00 00 05 ca fe de ad XX XX ... XX XX
20k -> 400k : 4k, 95, 0, 6, 0xfeedface
And when the client did a READ_PLUS of 64k at the start of the file,
it would get back a result of an ADH, some data, and a final ADH:
ADH {0, 4, 0, 0, 8, 0xfeedface}
data 4k
ADH {20k, 4k, 59, 0, 6, 0xfeedface}
8. Labeled NFS
8.1. Introduction
Access control models such as Unix permissions or Access Control
Lists are commonly referred to as Discretionary Access Control (DAC)
models. These systems base their access decisions on user identity
and resource ownership. In contrast Mandatory Access Control (MAC)
models base their access control decisions on the label on the
subject (usually a process) and the object it wishes to access
[Haynes13]. These labels may contain user identity information but
usually contain additional information. In DAC systems users are
free to specify the access rules for resources that they own. MAC
models base their security decisions on a system wide policy
established by an administrator or organization which the users do
not have the ability to override. In this section, we add a MAC
model to NFSv4.2.
The first change necessary is to devise a method for transporting and
storing security label data on NFSv4 file objects. Security labels
have several semantics that are met by NFSv4 recommended attributes
such as the ability to set the label value upon object creation.
Access control on these attributes are done through a combination of
two mechanisms. As with other recommended attributes on file objects
the usual DAC checks (ACLs and permission bits) will be performed to
ensure that proper file ownership is enforced. In addition a MAC
system MAY be employed on the client, server, or both to enforce
additional policy on what subjects may modify security label
information.
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The second change is to provide methods for the client to determine
if the security label has changed. A client which needs to know if a
label is going to change SHOULD request a delegation on that file.
In order to change the security label, the server will have to recall
all delegations. This will inform the client of the change. If a
client wants to detect if the label has changed, it MAY use VERIFY
and NVERIFY on FATTR4_CHANGE_SEC_LABEL to detect that the
FATTR4_SEC_LABEL has been modified.
An additional useful change would be modification to the RPC layer
used in NFSv4 to allow RPC calls to carry security labels. Such
modifications are outside the scope of this document.
8.2. Definitions
Label Format Specifier (LFS): is an identifier used by the client to
establish the syntactic format of the security label and the
semantic meaning of its components. These specifiers exist in a
registry associated with documents describing the format and
semantics of the label.
Label Format Registry: is the IANA registry containing all
registered LFS along with references to the documents that
describe the syntactic format and semantics of the security label.
Policy Identifier (PI): is an optional part of the definition of a
Label Format Specifier which allows for clients and server to
identify specific security policies.
Object: is a passive resource within the system that we wish to be
protected. Objects can be entities such as files, directories,
pipes, sockets, and many other system resources relevant to the
protection of the system state.
Subject: is an active entity usually a process which is requesting
access to an object.
MAC-Aware: is a server which can transmit and store object labels.
MAC-Functional: is a client or server which is Labeled NFS enabled.
Such a system can interpret labels and apply policies based on the
security system.
Multi-Level Security (MLS): is a traditional model where objects are
given a sensitivity level (Unclassified, Secret, Top Secret, etc)
and a category set [MLS].
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8.3. MAC Security Attribute
MAC models base access decisions on security attributes bound to
subjects and objects. This information can range from a user
identity for an identity based MAC model, sensitivity levels for
Multi-level security, or a type for Type Enforcement. These models
base their decisions on different criteria but the semantics of the
security attribute remain the same. The semantics required by the
security attributes are listed below:
o MUST provide flexibility with respect to the MAC model.
o MUST provide the ability to atomically set security information
upon object creation.
o MUST provide the ability to enforce access control decisions both
on the client and the server.
o MUST NOT expose an object to either the client or server name
space before its security information has been bound to it.
NFSv4 implements the security attribute as a recommended attribute.
These attributes have a fixed format and semantics, which conflicts
with the flexible nature of the security attribute. To resolve this
the security attribute consists of two components. The first
component is a LFS as defined in [Quigley11] to allow for
interoperability between MAC mechanisms. The second component is an
opaque field which is the actual security attribute data. To allow
for various MAC models, NFSv4 should be used solely as a transport
mechanism for the security attribute. It is the responsibility of
the endpoints to consume the security attribute and make access
decisions based on their respective models. In addition, creation of
objects through OPEN and CREATE allows for the security attribute to
be specified upon creation. By providing an atomic create and set
operation for the security attribute it is possible to enforce the
second and fourth requirements. The recommended attribute
FATTR4_SEC_LABEL (see Section 12.2.2) will be used to satisfy this
requirement.
8.3.1. Delegations
In the event that a security attribute is changed on the server while
a client holds a delegation on the file, both the server and the
client MUST follow the NFSv4.1 protocol (see Chapter 10 of [RFC5661])
with respect to attribute changes. It SHOULD flush all changes back
to the server and relinquish the delegation.
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8.3.2. Permission Checking
It is not feasible to enumerate all possible MAC models and even
levels of protection within a subset of these models. This means
that the NFSv4 client and servers cannot be expected to directly make
access control decisions based on the security attribute. Instead
NFSv4 should defer permission checking on this attribute to the host
system. These checks are performed in addition to existing DAC and
ACL checks outlined in the NFSv4 protocol. Section 8.6 gives a
specific example of how the security attribute is handled under a
particular MAC model.
8.3.3. Object Creation
When creating files in NFSv4 the OPEN and CREATE operations are used.
One of the parameters to these operations is an fattr4 structure
containing the attributes the file is to be created with. This
allows NFSv4 to atomically set the security attribute of files upon
creation. When a client is MAC-Functional it must always provide the
initial security attribute upon file creation. In the event that the
server is MAC-Functional as well, it should determine by policy
whether it will accept the attribute from the client or instead make
the determination itself. If the client is not MAC-Functional, then
the MAC-Functional server must decide on a default label. A more in
depth explanation can be found in Section 8.6.
8.3.4. Existing Objects
Note that under the MAC model, all objects must have labels.
Therefore, if an existing server is upgraded to include Labeled NFS
support, then it is the responsibility of the security system to
define the behavior for existing objects.
8.3.5. Label Changes
If there are open delegations on the file belonging to client other
than the one making the label change, then the process described in
Section 8.3.1 must be followed. In short, the delegation will be
recalled, which effectively notifies the client of the change.
Consider a system in which the clients enforce MAC checks and and the
server has a very simple security system which just stores the
labels. In this system, the MAC label check always allows access,
regardless of the subject label.
The way in which MAC labels are enforced is by the client. The
security policies on the client can be such that the client does not
have access to the file unless it has a delegation. The recall of
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the delegation will force the client to flush any cached content of
the file. The clients could also be configured to periodically
VERIFY/NVERIFY the FATTR4_CHANGE_SEC_LABEL attribute to determine
when the label has changed. When a change is detected, then the
client could take the costlier action of retrieving the
FATTR4_SEC_LABEL.
8.4. pNFS Considerations
The new FATTR4_SEC_LABEL attribute is metadata information and as
such the DS is not aware of the value contained on the MDS.
Fortunately, the NFSv4.1 protocol [RFC5661] already has provisions
for doing access level checks from the DS to the MDS. In order for
the DS to validate the subject label presented by the client, it
SHOULD utilize this mechanism.
8.5. Discovery of Server Labeled NFS Support
The server can easily determine that a client supports Labeled NFS
when it queries for the FATTR4_SEC_LABEL label for an object. The
client might need to discover which LFS the server supports.
The following compound MUST NOT be denied by any MAC label check:
PUTROOTFH, GETATTR {FATTR4_SEC_LABEL}
Note that the server might have imposed a security flavor on the root
that precludes such access. I.e., if the server requires kerberized
access and the client presents a compound with AUTH_SYS, then the
server is allowed to return NFS4ERR_WRONGSEC in this case. But if
the client presents a correct security flavor, then the server MUST
return the FATTR4_SEC_LABEL attribute with the supported LFS filled
in.
8.6. MAC Security NFS Modes of Operation
A system using Labeled NFS may operate in two modes. The first mode
provides the most protection and is called "full mode". In this mode
both the client and server implement a MAC model allowing each end to
make an access control decision. The remaining mode is called the
"guest mode" and in this mode one end of the connection is not
implementing a MAC model and thus offers less protection than full
mode.
8.6.1. Full Mode
Full mode environments consist of MAC-Functional NFSv4 servers and
clients and may be composed of mixed MAC models and policies. The
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system requires that both the client and server have an opportunity
to perform an access control check based on all relevant information
within the network. The file object security attribute is provided
using the mechanism described in Section 8.3.
Fully MAC-Functional NFSv4 servers are not possible in the absence of
RPC layer modifications to support subject label transport. However,
servers may make decisions based on the RPC credential information
available and future specifications may provide subject label
transport.
8.6.1.1. Initial Labeling and Translation
The ability to create a file is an action that a MAC model may wish
to mediate. The client is given the responsibility to determine the
initial security attribute to be placed on a file. This allows the
client to make a decision as to the acceptable security attributes to
create a file with before sending the request to the server. Once
the server receives the creation request from the client it may
choose to evaluate if the security attribute is acceptable.
Security attributes on the client and server may vary based on MAC
model and policy. To handle this the security attribute field has an
LFS component. This component is a mechanism for the host to
identify the format and meaning of the opaque portion of the security
attribute. A full mode environment may contain hosts operating in
several different LFSs. In this case a mechanism for translating the
opaque portion of the security attribute is needed. The actual
translation function will vary based on MAC model and policy and is
out of the scope of this document. If a translation is unavailable
for a given LFS then the request MUST be denied. Another recourse is
to allow the host to provide a fallback mapping for unknown security
attributes.
8.6.1.2. Policy Enforcement
In full mode access control decisions are made by both the clients
and servers. When a client makes a request it takes the security
attribute from the requesting process and makes an access control
decision based on that attribute and the security attribute of the
object it is trying to access. If the client denies that access an
RPC call to the server is never made. If however the access is
allowed the client will make a call to the NFS server.
When the server receives the request from the client it uses any
credential information conveyed in the RPC request and the attributes
of the object the client is trying to access to make an access
control decision. If the server's policy allows this access it will
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fulfill the client's request, otherwise it will return
NFS4ERR_ACCESS.
Future protocol extensions may also allow the server to factor into
the decision a security label extracted from the RPC request.
Implementations MAY validate security attributes supplied over the
network to ensure that they are within a set of attributes permitted
from a specific peer, and if not, reject them. Note that a system
may permit a different set of attributes to be accepted from each
peer.
8.6.1.3. Limited Server
A Limited Server mode (see Section 3.5.2 of [Haynes13]) consists of a
server which is label aware, but does not enforce policies. Such a
server will store and retrieve all object labels presented by
clients, utilize the methods described in Section 8.3.5 to allow the
clients to detect changing labels, but may not factor the label into
access decisions. Instead, it will expect the clients to enforce all
such access locally.
8.6.2. Guest Mode
Guest mode implies that either the client or the server does not
handle labels. If the client is not Labeled NFS aware, then it will
not offer subject labels to the server. The server is the only
entity enforcing policy, and may selectively provide standard NFS
services to clients based on their authentication credentials and/or
associated network attributes (e.g., IP address, network interface).
The level of trust and access extended to a client in this mode is
configuration-specific. If the server is not Labeled NFS aware, then
it will not return object labels to the client. Clients in this
environment are may consist of groups implementing different MAC
model policies. The system requires that all clients in the
environment be responsible for access control checks.
8.7. Security Considerations
This entire chapter deals with security issues.
Depending on the level of protection the MAC system offers there may
be a requirement to tightly bind the security attribute to the data.
When only one of the client or server enforces labels, it is
important to realize that the other side is not enforcing MAC
protections. Alternate methods might be in use to handle the lack of
MAC support and care should be taken to identify and mitigate threats
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from possible tampering outside of these methods.
An example of this is that a server that modifies READDIR or LOOKUP
results based on the client's subject label might want to always
construct the same subject label for a client which does not present
one. This will prevent a non-Labeled NFS client from mixing entries
in the directory cache.
9. Sharing change attribute implementation details with NFSv4 clients
9.1. Introduction
Although both the NFSv4 [I-D.ietf-nfsv4-rfc3530bis] and NFSv4.1
protocol [RFC5661], define the change attribute as being mandatory to
implement, there is little in the way of guidance. The only mandated
feature is that the value must change whenever the file data or
metadata change.
While this allows for a wide range of implementations, it also leaves
the client with a conundrum: how does it determine which is the most
recent value for the change attribute in a case where several RPC
calls have been issued in parallel? In other words if two COMPOUNDs,
both containing WRITE and GETATTR requests for the same file, have
been issued in parallel, how does the client determine which of the
two change attribute values returned in the replies to the GETATTR
requests correspond to the most recent state of the file? In some
cases, the only recourse may be to send another COMPOUND containing a
third GETATTR that is fully serialized with the first two.
NFSv4.2 avoids this kind of inefficiency by allowing the server to
share details about how the change attribute is expected to evolve,
so that the client may immediately determine which, out of the
several change attribute values returned by the server, is the most
recent. change_attr_type is defined as a new recommended attribute
(see Section 12.2.1), and is per file system.
10. Security Considerations
NFSv4.2 has all of the security concerns present in NFSv4.1 (see
Section 21 of [RFC5661]) and those present in the Server-side Copy
(see Section 3.4) and in Labeled NFS (see Section 8.7).
11. Error Values
NFS error numbers are assigned to failed operations within a Compound
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(COMPOUND or CB_COMPOUND) request. A Compound request contains a
number of NFS operations that have their results encoded in sequence
in a Compound reply. The results of successful operations will
consist of an NFS4_OK status followed by the encoded results of the
operation. If an NFS operation fails, an error status will be
entered in the reply and the Compound request will be terminated.
11.1. Error Definitions
Protocol Error Definitions
+--------------------------+--------+------------------+
| Error | Number | Description |
+--------------------------+--------+------------------+
| NFS4ERR_BADLABEL | 10093 | Section 11.1.3.1 |
| NFS4ERR_METADATA_NOTSUPP | 10090 | Section 11.1.2.1 |
| NFS4ERR_OFFLOAD_DENIED | 10091 | Section 11.1.2.2 |
| NFS4ERR_PARTNER_NO_AUTH | 10089 | Section 11.1.2.3 |
| NFS4ERR_PARTNER_NOTSUPP | 10088 | Section 11.1.2.4 |
| NFS4ERR_UNION_NOTSUPP | 10094 | Section 11.1.1.1 |
| NFS4ERR_WRONG_LFS | 10092 | Section 11.1.3.2 |
+--------------------------+--------+------------------+
Table 1
11.1.1. General Errors
This section deals with errors that are applicable to a broad set of
different purposes.
11.1.1.1. NFS4ERR_UNION_NOTSUPP (Error Code 10094)
One of the arguments to the operation is a discriminated union and
while the server supports the given operation, it does not support
the selected arm of the discriminated union. For an example, see
READ_PLUS (Section 14.10).
11.1.2. Server to Server Copy Errors
These errors deal with the interaction between server to server
copies.
11.1.2.1. NFS4ERR_METADATA_NOTSUPP (Error Code 10090)
The destination file cannot support the same metadata as the source
file.
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11.1.2.2. NFS4ERR_OFFLOAD_DENIED (Error Code 10091)
The copy offload operation is supported by both the source and the
destination, but the destination is not allowing it for this file.
If the client sees this error, it should fall back to the normal copy
semantics.
11.1.2.3. NFS4ERR_PARTNER_NO_AUTH (Error Code 10089)
The source server does not authorize a server-to-server copy offload
operation. This may be due to the client's failure to send the
COPY_NOTIFY operation to the source server, the source server
receiving a server-to-server copy offload request after the copy
lease time expired, or for some other permission problem.
11.1.2.4. NFS4ERR_PARTNER_NOTSUPP (Error Code 10088)
The remote server does not support the server-to-server copy offload
protocol.
11.1.3. Labeled NFS Errors
These errors are used in Labeled NFS.
11.1.3.1. NFS4ERR_BADLABEL (Error Code 10093)
The label specified is invalid in some manner.
11.1.3.2. NFS4ERR_WRONG_LFS (Error Code 10092)
The LFS specified in the subject label is not compatible with the LFS
in the object label.
11.2. New Operations and Their Valid Errors
This section contains a table that gives the valid error returns for
each new NFSv4.2 protocol operation. The error code NFS4_OK
(indicating no error) is not listed but should be understood to be
returnable by all new operations. The error values for all other
operations are defined in Section 15.2 of [RFC5661].
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Valid Error Returns for Each New Protocol Operation
+----------------+--------------------------------------------------+
| Operation | Errors |
+----------------+--------------------------------------------------+
| COPY | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, |
| | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, |
| | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, |
| | NFS4ERR_DELEG_REVOKED, NFS4ERR_DQUOT, |
| | NFS4ERR_EXPIRED, NFS4ERR_FBIG, |
| | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, |
| | NFS4ERR_IO, NFS4ERR_ISDIR, NFS4ERR_LOCKED, |
| | NFS4ERR_METADATA_NOTSUPP, NFS4ERR_MOVED, |
| | NFS4ERR_NOFILEHANDLE, NFS4ERR_NOSPC, |
| | NFS4ERR_OFFLOAD_DENIED, NFS4ERR_OLD_STATEID, |
| | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, |
| | NFS4ERR_PARTNER_NO_AUTH, |
| | NFS4ERR_PARTNER_NOTSUPP, NFS4ERR_PNFS_IO_HOLE, |
| | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, |
| | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, |
| | NFS4ERR_ROFS, NFS4ERR_SERVERFAULT, |
| | NFS4ERR_STALE, NFS4ERR_SYMLINK, |
| | NFS4ERR_TOO_MANY_OPS, NFS4ERR_WRONG_TYPE |
| COPY_NOTIFY | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, |
| | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, |
| | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, |
| | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, |
| | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, |
| | NFS4ERR_ISDIR, NFS4ERR_IO, NFS4ERR_LOCKED, |
| | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, |
| | NFS4ERR_OLD_STATEID, NFS4ERR_OPENMODE, |
| | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_PNFS_IO_HOLE, |
| | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, |
| | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, |
| | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, |
| | NFS4ERR_SYMLINK, NFS4ERR_TOO_MANY_OPS, |
| | NFS4ERR_WRONG_TYPE |
| OFFLOAD_ABORT | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, |
| | NFS4ERR_BAD_STATEID, NFS4ERR_COMPLETE_ALREADY, |
| | NFS4ERR_DEADSESSION, NFS4ERR_EXPIRED, |
| | NFS4ERR_DELAY, NFS4ERR_GRACE, NFS4ERR_NOTSUPP, |
| | NFS4ERR_OLD_STATEID, NFS4ERR_OP_NOT_IN_SESSION, |
| | NFS4ERR_SERVERFAULT, NFS4ERR_TOO_MANY_OPS |
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| OFFLOAD_REVOKE | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, |
| | NFS4ERR_COMPLETE_ALREADY, NFS4ERR_DELAY, |
| | NFS4ERR_GRACE, NFS4ERR_INVALID, NFS4ERR_MOVED, |
| | NFS4ERR_NOTSUPP, NFS4ERR_OP_NOT_IN_SESSION, |
| | NFS4ERR_SERVERFAULT, NFS4ERR_TOO_MANY_OPS |
| OFFLOAD_STATUS | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, |
| | NFS4ERR_BAD_STATEID, NFS4ERR_COMPLETE_ALREADY, |
| | NFS4ERR_DEADSESSION, NFS4ERR_EXPIRED, |
| | NFS4ERR_DELAY, NFS4ERR_GRACE, NFS4ERR_NOTSUPP, |
| | NFS4ERR_OLD_STATEID, NFS4ERR_OP_NOT_IN_SESSION, |
| | NFS4ERR_SERVERFAULT, NFS4ERR_TOO_MANY_OPS |
| READ_PLUS | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, |
| | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, |
| | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, |
| | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, |
| | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, |
| | NFS4ERR_ISDIR, NFS4ERR_IO, NFS4ERR_LOCKED, |
| | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, |
| | NFS4ERR_OLD_STATEID, NFS4ERR_OPENMODE, |
| | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_PNFS_IO_HOLE, |
| | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, |
| | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, |
| | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, |
| | NFS4ERR_SYMLINK, NFS4ERR_TOO_MANY_OPS, |
| | NFS4ERR_UNION_NOTSUPP, NFS4ERR_WRONG_TYPE |
| SEEK | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, |
| | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, |
| | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, |
| | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, |
| | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, |
| | NFS4ERR_ISDIR, NFS4ERR_IO, NFS4ERR_LOCKED, |
| | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, |
| | NFS4ERR_OLD_STATEID, NFS4ERR_OPENMODE, |
| | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_PNFS_IO_HOLE, |
| | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, |
| | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, |
| | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, |
| | NFS4ERR_SYMLINK, NFS4ERR_TOO_MANY_OPS, |
| | NFS4ERR_UNION_NOTSUPP, NFS4ERR_WRONG_TYPE |
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| SEQUENCE | NFS4ERR_BADSESSION, NFS4ERR_BADSLOT, |
| | NFS4ERR_BADXDR, NFS4ERR_BAD_HIGH_SLOT, |
| | NFS4ERR_CONN_NOT_BOUND_TO_SESSION, |
| | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, |
| | NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, |
| | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, |
| | NFS4ERR_SEQUENCE_POS, NFS4ERR_SEQ_FALSE_RETRY, |
| | NFS4ERR_SEQ_MISORDERED, NFS4ERR_TOO_MANY_OPS |
| WRITE_PLUS | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, |
| | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, |
| | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, |
| | NFS4ERR_DELEG_REVOKED, NFS4ERR_DQUOT, |
| | NFS4ERR_EXPIRED, NFS4ERR_FBIG, |
| | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, |
| | NFS4ERR_IO, NFS4ERR_ISDIR, NFS4ERR_LOCKED, |
| | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, |
| | NFS4ERR_NOSPC, NFS4ERR_OLD_STATEID, |
| | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, |
| | NFS4ERR_PNFS_IO_HOLE, NFS4ERR_PNFS_NO_LAYOUT, |
| | NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, |
| | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, |
| | NFS4ERR_ROFS, NFS4ERR_SERVERFAULT, |
| | NFS4ERR_STALE, NFS4ERR_SYMLINK, |
| | NFS4ERR_TOO_MANY_OPS, NFS4ERR_UNION_NOTSUPP, |
| | NFS4ERR_WRONG_TYPE |
+----------------+--------------------------------------------------+
Table 2
11.3. New Callback Operations and Their Valid Errors
This section contains a table that gives the valid error returns for
each new NFSv4.2 callback operation. The error code NFS4_OK
(indicating no error) is not listed but should be understood to be
returnable by all new callback operations. The error values for all
other callback operations are defined in Section 15.3 of [RFC5661].
Valid Error Returns for Each New Protocol Callback Operation
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+------------+------------------------------------------------------+
| Callback | Errors |
| Operation | |
+------------+------------------------------------------------------+
| CB_OFFLOAD | NFS4ERR_BADHANDLE, NFS4ERR_BADXDR, |
| | NFS4ERR_BAD_STATEID, NFS4ERR_DELAY, |
| | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_REP_TOO_BIG, |
| | NFS4ERR_REP_TOO_BIG_TO_CACHE, NFS4ERR_REQ_TOO_BIG, |
| | NFS4ERR_RETRY_UNCACHED_REP, NFS4ERR_SERVERFAULT, |
| | NFS4ERR_TOO_MANY_OPS |
+------------+------------------------------------------------------+
Table 3
12. New File Attributes
12.1. New RECOMMENDED Attributes - List and Definition References
The list of new RECOMMENDED attributes appears in Table 4. The
meaning of the columns of the table are:
Name: The name of the attribute.
Id: The number assigned to the attribute. In the event of conflicts
between the assigned number and [4.2xdr], the latter is likely
authoritative, but should be resolved with Errata to this document
and/or [4.2xdr]. See [IESG08] for the Errata process.
Data Type: The XDR data type of the attribute.
Acc: Access allowed to the attribute.
R means read-only (GETATTR may retrieve, SETATTR may not set).
W means write-only (SETATTR may set, GETATTR may not retrieve).
R W means read/write (GETATTR may retrieve, SETATTR may set).
Defined in: The section of this specification that describes the
attribute.
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+------------------+----+-------------------+-----+----------------+
| Name | Id | Data Type | Acc | Defined in |
+------------------+----+-------------------+-----+----------------+
| change_attr_type | 79 | change_attr_type4 | R | Section 12.2.1 |
| sec_label | 80 | sec_label4 | R W | Section 12.2.2 |
| change_sec_label | 81 | change_sec_label4 | R | Section 12.2.3 |
| space_reserved | 77 | boolean | R W | Section 12.2.4 |
| space_freed | 78 | length4 | R | Section 12.2.5 |
+------------------+----+-------------------+-----+----------------+
Table 4
12.2. Attribute Definitions
12.2.1. Attribute 79: change_attr_type
enum change_attr_type4 {
NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR = 0,
NFS4_CHANGE_TYPE_IS_VERSION_COUNTER = 1,
NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS = 2,
NFS4_CHANGE_TYPE_IS_TIME_METADATA = 3,
NFS4_CHANGE_TYPE_IS_UNDEFINED = 4
};
change_attr_type is a per file system attribute which enables the
NFSv4.2 server to provide additional information about how it expects
the change attribute value to evolve after the file data, or metadata
has changed. While Section 5.4 of [RFC5661] discusses per file
system attributes, it is expected that the value of change_attr_type
not depend on the value of "homogeneous" and only changes in the
event of a migration.
NFS4_CHANGE_TYPE_IS_UNDEFINED: The change attribute does not take
values that fit into any of these categories.
NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR: The change attribute value MUST
monotonically increase for every atomic change to the file
attributes, data, or directory contents.
NFS4_CHANGE_TYPE_IS_VERSION_COUNTER: The change attribute value MUST
be incremented by one unit for every atomic change to the file
attributes, data, or directory contents. This property is
preserved when writing to pNFS data servers.
NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS: The change attribute
value MUST be incremented by one unit for every atomic change to
the file attributes, data, or directory contents. In the case
where the client is writing to pNFS data servers, the number of
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increments is not guaranteed to exactly match the number of
writes.
NFS4_CHANGE_TYPE_IS_TIME_METADATA: The change attribute is
implemented as suggested in the NFSv4 spec
[I-D.ietf-nfsv4-rfc3530bis] in terms of the time_metadata
attribute.
If either NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR,
NFS4_CHANGE_TYPE_IS_VERSION_COUNTER, or
NFS4_CHANGE_TYPE_IS_TIME_METADATA are set, then the client knows at
the very least that the change attribute is monotonically increasing,
which is sufficient to resolve the question of which value is the
most recent.
If the client sees the value NFS4_CHANGE_TYPE_IS_TIME_METADATA, then
by inspecting the value of the 'time_delta' attribute it additionally
has the option of detecting rogue server implementations that use
time_metadata in violation of the spec.
If the client sees NFS4_CHANGE_TYPE_IS_VERSION_COUNTER, it has the
ability to predict what the resulting change attribute value should
be after a COMPOUND containing a SETATTR, WRITE, or CREATE. This
again allows it to detect changes made in parallel by another client.
The value NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS permits the
same, but only if the client is not doing pNFS WRITEs.
Finally, if the server does not support change_attr_type or if
NFS4_CHANGE_TYPE_IS_UNDEFINED is set, then the server SHOULD make an
effort to implement the change attribute in terms of the
time_metadata attribute.
12.2.2. Attribute 80: sec_label
typedef uint32_t policy4;
struct labelformat_spec4 {
policy4 lfs_lfs;
policy4 lfs_pi;
};
struct sec_label4 {
labelformat_spec4 slai_lfs;
opaque slai_data<>;
};
The FATTR4_SEC_LABEL contains an array of two components with the
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first component being an LFS. It serves to provide the receiving end
with the information necessary to translate the security attribute
into a form that is usable by the endpoint. Label Formats assigned
an LFS may optionally choose to include a Policy Identifier field to
allow for complex policy deployments. The LFS and Label Format
Registry are described in detail in [Quigley11]. The translation
used to interpret the security attribute is not specified as part of
the protocol as it may depend on various factors. The second
component is an opaque section which contains the data of the
attribute. This component is dependent on the MAC model to interpret
and enforce.
In particular, it is the responsibility of the LFS specification to
define a maximum size for the opaque section, slai_data<>. When
creating or modifying a label for an object, the client needs to be
guaranteed that the server will accept a label that is sized
correctly. By both client and server being part of a specific MAC
model, the client will be aware of the size.
If a server supports sec_label, then it MUST also support
change_sec_label. Any modification to sec_label MUST modify the
value for change_sec_label.
12.2.3. Attribute 81: change_sec_label
The change_sec_label attribute is a read-only attribute per file. If
the value of sec_label for a file is not the same at two disparate
times then the values of change_sec_label at those times MUST be
different as well. The value of change_sec_label MAY change at other
times as well, but this should be rare, as that will require the
client to abort any operation in progress, re-read the label, and
retry the operation. As the sec_label is not bounded by size, this
attribute allows for VERIFY and NVERIFY to quickly determine if the
sec_label has been modified.
12.2.4. Attribute 77: space_reserved
The space_reserve attribute is a read/write attribute of type
boolean. It is a per file attribute and applies during the lifetime
of the file or until it is turned off. When the space_reserved
attribute is set via SETATTR, the server must ensure that there is
disk space to accommodate every byte in the file before it can return
success. If the server cannot guarantee this, it must return
NFS4ERR_NOSPC.
If the client tries to grow a file which has the space_reserved
attribute set, the server must guarantee that there is disk space to
accommodate every byte in the file with the new size before it can
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return success. If the server cannot guarantee this, it must return
NFS4ERR_NOSPC.
It is not required that the server allocate the space to the file
before returning success. The allocation can be deferred, however,
it must be guaranteed that it will not fail for lack of space.
The value of space_reserved can be obtained at any time through
GETATTR. If the size is retrieved at the same time, the client can
determine the size of the reservation.
In order to avoid ambiguity, the space_reserve bit cannot be set
along with the size bit in SETATTR. Increasing the size of a file
with space_reserve set will fail if space reservation cannot be
guaranteed for the new size. If the file size is decreased, space
reservation is only guaranteed for the new size. If a hole is
punched into the file, then the reservation is not changed.
12.2.5. Attribute 78: space_freed
space_freed gives the number of bytes freed if the file is deleted.
This attribute is read only and is of type length4. It is a per file
attribute.
13. Operations: REQUIRED, RECOMMENDED, or OPTIONAL
The following tables summarize the operations of the NFSv4.2 protocol
and the corresponding designation of REQUIRED, RECOMMENDED, and
OPTIONAL to implement or either OBSOLESCENT or MUST NOT implement.
The designation of OBSOLESCENT is reserved for those operations which
are defined in either NFSv4.0 or NFSv4.1 and are intended to be
classified as MUST NOT be implemented in NFSv4.3. The designation of
MUST NOT implement is reserved for those operations that were defined
in either NFSv4.0 or NFSV4.1 and MUST NOT be implemented in NFSv4.2.
For the most part, the REQUIRED, RECOMMENDED, or OPTIONAL designation
for operations sent by the client is for the server implementation.
The client is generally required to implement the operations needed
for the operating environment for which it serves. For example, a
read-only NFSv4.2 client would have no need to implement the WRITE
operation and is not required to do so.
The REQUIRED or OPTIONAL designation for callback operations sent by
the server is for both the client and server. Generally, the client
has the option of creating the backchannel and sending the operations
on the fore channel that will be a catalyst for the server sending
callback operations. A partial exception is CB_RECALL_SLOT; the only
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way the client can avoid supporting this operation is by not creating
a backchannel.
Since this is a summary of the operations and their designation,
there are subtleties that are not presented here. Therefore, if
there is a question of the requirements of implementation, the
operation descriptions themselves must be consulted along with other
relevant explanatory text within this either specification or that of
NFSv4.1 [RFC5661].
The abbreviations used in the second and third columns of the table
are defined as follows.
REQ REQUIRED to implement
REC RECOMMENDED to implement
OPT OPTIONAL to implement
MNI MUST NOT implement
OBS Also OBSOLESCENT for future versions.
For the NFSv4.2 features that are OPTIONAL, the operations that
support those features are OPTIONAL, and the server would return
NFS4ERR_NOTSUPP in response to the client's use of those operations.
If an OPTIONAL feature is supported, it is possible that a set of
operations related to the feature become REQUIRED to implement. The
third column of the table designates the feature(s) and if the
operation is REQUIRED or OPTIONAL in the presence of support for the
feature.
The OPTIONAL features identified and their abbreviations are as
follows:
pNFS Parallel NFS
FDELG File Delegations
DDELG Directory Delegations
COPY Server Side Copy
ADH Application Data Holes
Operations
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+----------------------+---------------------+----------------------+
| Operation | EOL, REQ, REC, OPT, | Feature (REQ, REC, |
| | or MNI | or OPT) |
+----------------------+---------------------+----------------------+
| ACCESS | REQ | |
| BACKCHANNEL_CTL | REQ | |
| BIND_CONN_TO_SESSION | REQ | |
| CLOSE | REQ | |
| COMMIT | REQ | |
| COPY | OPT | COPY (REQ) |
| OFFLOAD_ABORT | OPT | COPY (REQ) |
| COPY_NOTIFY | OPT | COPY (REQ) |
| OFFLOAD_REVOKE | OPT | COPY (REQ) |
| OFFLOAD_STATUS | OPT | COPY (REQ) |
| CREATE | REQ | |
| CREATE_SESSION | REQ | |
| DELEGPURGE | OPT | FDELG (REQ) |
| DELEGRETURN | OPT | FDELG, DDELG, pNFS |
| | | (REQ) |
| DESTROY_CLIENTID | REQ | |
| DESTROY_SESSION | REQ | |
| EXCHANGE_ID | REQ | |
| FREE_STATEID | REQ | |
| GETATTR | REQ | |
| GETDEVICEINFO | OPT | pNFS (REQ) |
| GETDEVICELIST | OPT | pNFS (OPT) |
| GETFH | REQ | |
| WRITE_PLUS | OPT | ADH (REQ) |
| GET_DIR_DELEGATION | OPT | DDELG (REQ) |
| LAYOUTCOMMIT | OPT | pNFS (REQ) |
| LAYOUTGET | OPT | pNFS (REQ) |
| LAYOUTRETURN | OPT | pNFS (REQ) |
| LINK | OPT | |
| LOCK | REQ | |
| LOCKT | REQ | |
| LOCKU | REQ | |
| LOOKUP | REQ | |
| LOOKUPP | REQ | |
| NVERIFY | REQ | |
| OPEN | REQ | |
| OPENATTR | OPT | |
| OPEN_CONFIRM | MNI | |
| OPEN_DOWNGRADE | REQ | |
| PUTFH | REQ | |
| PUTPUBFH | REQ | |
| PUTROOTFH | REQ | |
| READ | REQ (OBS) | |
| READDIR | REQ | |
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| READLINK | OPT | |
| READ_PLUS | OPT | ADH (REQ) |
| RECLAIM_COMPLETE | REQ | |
| RELEASE_LOCKOWNER | MNI | |
| REMOVE | REQ | |
| RENAME | REQ | |
| RENEW | MNI | |
| RESTOREFH | REQ | |
| SAVEFH | REQ | |
| SECINFO | REQ | |
| SECINFO_NO_NAME | REC | pNFS file layout |
| | | (REQ) |
| SEQUENCE | REQ | |
| SETATTR | REQ | |
| SETCLIENTID | MNI | |
| SETCLIENTID_CONFIRM | MNI | |
| SET_SSV | REQ | |
| TEST_STATEID | REQ | |
| VERIFY | REQ | |
| WANT_DELEGATION | OPT | FDELG (OPT) |
| WRITE | REQ (OBS) | |
+----------------------+---------------------+----------------------+
Callback Operations
+-------------------------+-------------------+---------------------+
| Operation | REQ, REC, OPT, or | Feature (REQ, REC, |
| | MNI | or OPT) |
+-------------------------+-------------------+---------------------+
| CB_OFFLOAD | OPT | COPY (REQ) |
| CB_GETATTR | OPT | FDELG (REQ) |
| CB_LAYOUTRECALL | OPT | pNFS (REQ) |
| CB_NOTIFY | OPT | DDELG (REQ) |
| CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) |
| CB_NOTIFY_LOCK | OPT | |
| CB_PUSH_DELEG | OPT | FDELG (OPT) |
| CB_RECALL | OPT | FDELG, DDELG, pNFS |
| | | (REQ) |
| CB_RECALL_ANY | OPT | FDELG, DDELG, pNFS |
| | | (REQ) |
| CB_RECALL_SLOT | REQ | |
| CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS (REQ) |
| CB_SEQUENCE | OPT | FDELG, DDELG, pNFS |
| | | (REQ) |
| CB_WANTS_CANCELLED | OPT | FDELG, DDELG, pNFS |
| | | (REQ) |
+-------------------------+-------------------+---------------------+
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14. NFSv4.2 Operations
14.1. Operation 59: COPY - Initiate a server-side copy
14.1.1. ARGUMENT
struct COPY4args {
/* SAVED_FH: source file */
/* CURRENT_FH: destination file */
stateid4 ca_src_stateid;
stateid4 ca_dst_stateid;
offset4 ca_src_offset;
offset4 ca_dst_offset;
length4 ca_count;
netloc4 ca_source_server<>;
};
14.1.2. RESULT
union COPY4res switch (nfsstat4 cr_status) {
case NFS4_OK:
write_response4 resok4;
default:
length4 cr_bytes_copied;
};
14.1.3. DESCRIPTION
The COPY operation is used for both intra-server and inter-server
copies. In both cases, the COPY is always sent from the client to
the destination server of the file copy. The COPY operation requests
that a file be copied from the location specified by the SAVED_FH
value to the location specified by the CURRENT_FH.
The SAVED_FH must be a regular file. If SAVED_FH is not a regular
file, the operation MUST fail and return NFS4ERR_WRONG_TYPE.
In order to set SAVED_FH to the source file handle, the compound
procedure requesting the COPY will include a sub-sequence of
operations such as
PUTFH source-fh
SAVEFH
If the request is for a server-to-server copy, the source-fh is a
filehandle from the source server and the compound procedure is being
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executed on the destination server. In this case, the source-fh is a
foreign filehandle on the server receiving the COPY request. If
either PUTFH or SAVEFH checked the validity of the filehandle, the
operation would likely fail and return NFS4ERR_STALE.
If a server supports the server-to-server COPY feature, a PUTFH
followed by a SAVEFH MUST NOT return NFS4ERR_STALE for either
operation. These restrictions do not pose substantial difficulties
for servers. The CURRENT_FH and SAVED_FH may be validated in the
context of the operation referencing them and an NFS4ERR_STALE error
returned for an invalid file handle at that point.
For an intra-server copy, both the ca_src_stateid and ca_dst_stateid
MUST refer to either open or locking states provided earlier by the
server. If either stateid is invalid, then the operation MUST fail.
If the request is for a inter-server copy, then the ca_src_stateid
can be ignored. If ca_dst_stateid is invalid, then the operation
MUST fail.
The CURRENT_FH specifies the destination of the copy operation. The
CURRENT_FH MUST be a regular file and not a directory. Note, the
file MUST exist before the COPY operation begins. It is the
responsibility of the client to create the file if necessary,
regardless of the actual copy protocol used. If the file cannot be
created in the destination file system (due to file name
restrictions, such as case or length), the COPY operation MUST NOT be
called.
The ca_src_offset is the offset within the source file from which the
data will be read, the ca_dst_offset is the offset within the
destination file to which the data will be written, and the ca_count
is the number of bytes that will be copied. An offset of 0 (zero)
specifies the start of the file. A count of 0 (zero) requests that
all bytes from ca_src_offset through EOF be copied to the
destination. If concurrent modifications to the source file overlap
with the source file region being copied, the data copied may include
all, some, or none of the modifications. The client can use standard
NFS operations (e.g., OPEN with OPEN4_SHARE_DENY_WRITE or mandatory
byte range locks) to protect against concurrent modifications if the
client is concerned about this. If the source file's end of file is
being modified in parallel with a copy that specifies a count of 0
(zero) bytes, the amount of data copied is implementation dependent
(clients may guard against this case by specifying a non-zero count
value or preventing modification of the source file as mentioned
above).
If the source offset or the source offset plus count is greater than
or equal to the size of the source file, the operation will fail with
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NFS4ERR_INVAL. The destination offset or destination offset plus
count may be greater than the size of the destination file. This
allows for the client to issue parallel copies to implement
operations such as "cat file1 file2 file3 file4 > dest".
If the ca_source_server list is specified, then this is an inter-
server copy operation and the source file is on a remote server. The
client is expected to have previously issued a successful COPY_NOTIFY
request to the remote source server. The ca_source_server list MUST
be the same as the COPY_NOTIFY response's cnr_source_server list. If
the client includes the entries from the COPY_NOTIFY response's
cnr_source_server list in the ca_source_server list, the source
server can indicate a specific copy protocol for the destination
server to use by returning a URL, which specifies both a protocol
service and server name. Server-to-server copy protocol
considerations are described in Section 3.2.5 and Section 3.4.1.
The copying of any and all attributes on the source file is the
responsibility of both the client and the copy protocol. Any
attribute which is both exposed via the NFS protocol on the source
file and set SHOULD be copied to the destination file. Any attribute
supported by the destination server that is not set on the source
file SHOULD be left unset. If the client cannot copy an attribute
from the source to destination, it MAY fail the copy transaction.
Metadata attributes not exposed via the NFS protocol SHOULD be copied
to the destination file where appropriate via the copy protocol.
Note that if the copy protocol is NFSv4.x, then these attributes will
be lost.
The destination file's named attributes are not duplicated from the
source file. After the copy process completes, the client MAY
attempt to duplicate named attributes using standard NFSv4
operations. However, the destination file's named attribute
capabilities MAY be different from the source file's named attribute
capabilities.
If the operation does not result in an immediate failure, the server
will return NFS4_OK, and the CURRENT_FH will remain the destination's
filehandle.
If an immediate failure does occur, cr_bytes_copied will be set to
the number of bytes copied to the destination file before the error
occurred. The cr_bytes_copied value indicates the number of bytes
copied but not which specific bytes have been copied.
A return of NFS4_OK indicates that either the operation is complete
or the operation was initiated and a callback will be used to deliver
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the final status of the operation.
If the cr_callback_id is returned, this indicates that the operation
was initiated and a CB_OFFLOAD callback will deliver the final
results of the operation. The cr_callback_id stateid is termed a
copy stateid in this context. The server is given the option of
returning the results in a callback because the data may require a
relatively long period of time to copy.
If no cr_callback_id is returned, the operation completed
synchronously and no callback will be issued by the server. The
completion status of the operation is indicated by cr_status.
If the copy completes successfully, either synchronously or
asynchronously, the data copied from the source file to the
destination file MUST appear identical to the NFS client. However,
the NFS server's on disk representation of the data in the source
file and destination file MAY differ. For example, the NFS server
might encrypt, compress, deduplicate, or otherwise represent the on
disk data in the source and destination file differently.
14.2. Operation 60: OFFLOAD_ABORT - Cancel a server-side copy
14.2.1. ARGUMENT
struct OFFLOAD_ABORT4args {
/* CURRENT_FH: destination file */
stateid4 oaa_stateid;
};
14.2.2. RESULT
struct OFFLOAD_ABORT4res {
nfsstat4 oar_status;
};
14.2.3. DESCRIPTION
OFFLOAD_ABORT is used for both intra- and inter-server asynchronous
copies. The OFFLOAD_ABORT operation allows the client to cancel a
server-side copy operation that it initiated. This operation is sent
in a COMPOUND request from the client to the destination server.
This operation may be used to cancel a copy when the application that
requested the copy exits before the operation is completed or for
some other reason.
The request contains the filehandle and copy stateid cookies that act
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as the context for the previously initiated copy operation.
The result's oar_status field indicates whether the cancel was
successful or not. A value of NFS4_OK indicates that the copy
operation was canceled and no callback will be issued by the server.
A copy operation that is successfully canceled may result in none,
some, or all of the data and/or metadata copied.
If the server supports asynchronous copies, the server is REQUIRED to
support the OFFLOAD_ABORT operation.
14.3. Operation 61: COPY_NOTIFY - Notify a source server of a future
copy
14.3.1. ARGUMENT
struct COPY_NOTIFY4args {
/* CURRENT_FH: source file */
stateid4 cna_src_stateid;
netloc4 cna_destination_server;
};
14.3.2. RESULT
struct COPY_NOTIFY4resok {
nfstime4 cnr_lease_time;
netloc4 cnr_source_server<>;
};
union COPY_NOTIFY4res switch (nfsstat4 cnr_status) {
case NFS4_OK:
COPY_NOTIFY4resok resok4;
default:
void;
};
14.3.3. DESCRIPTION
This operation is used for an inter-server copy. A client sends this
operation in a COMPOUND request to the source server to authorize a
destination server identified by cna_destination_server to read the
file specified by CURRENT_FH on behalf of the given user.
The cna_src_stateid MUST refer to either open or locking states
provided earlier by the server. If it is invalid, then the operation
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MUST fail.
The cna_destination_server MUST be specified using the netloc4
network location format. The server is not required to resolve the
cna_destination_server address before completing this operation.
If this operation succeeds, the source server will allow the
cna_destination_server to copy the specified file on behalf of the
given user as long as both of the following conditions are met:
o The destination server begins reading the source file before the
cnr_lease_time expires. If the cnr_lease_time expires while the
destination server is still reading the source file, the
destination server is allowed to finish reading the file.
o The client has not issued a COPY_REVOKE for the same combination
of user, filehandle, and destination server.
The cnr_lease_time is chosen by the source server. A cnr_lease_time
of 0 (zero) indicates an infinite lease. To avoid the need for
synchronized clocks, copy lease times are granted by the server as a
time delta. To renew the copy lease time the client should resend
the same copy notification request to the source server.
A successful response will also contain a list of netloc4 network
location formats called cnr_source_server, on which the source is
willing to accept connections from the destination. These might not
be reachable from the client and might be located on networks to
which the client has no connection.
If the client wishes to perform an inter-server copy, the client MUST
send a COPY_NOTIFY to the source server. Therefore, the source
server MUST support COPY_NOTIFY.
For a copy only involving one server (the source and destination are
on the same server), this operation is unnecessary.
14.4. Operation 62: OFFLOAD_REVOKE - Revoke a destination server's copy
privileges
14.4.1. ARGUMENT
struct OFFLOAD_REVOKE4args {
/* CURRENT_FH: source file */
netloc4 ora_destination_server;
};
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14.4.2. RESULT
struct OFFLOAD_REVOKE4res {
nfsstat4 orr_status;
};
14.4.3. DESCRIPTION
This operation is used for an inter-server copy. A client sends this
operation in a COMPOUND request to the source server to revoke the
authorization of a destination server identified by
ora_destination_server from reading the file specified by CURRENT_FH
on behalf of given user. If the ora_destination_server has already
begun copying the file, a successful return from this operation
indicates that further access will be prevented.
The ora_destination_server MUST be specified using the netloc4
network location format. The server is not required to resolve the
ora_destination_server address before completing this operation.
The client uses OFFLOAD_ABORT to inform the destination to stop the
active transfer and OFFLOAD_REVOKE to inform the source to not allow
any more copy requests from the destination. The OFFLOAD_REVOKE
operation is also useful in situations in which the source server
granted a very long or infinite lease on the destination server's
ability to read the source file and all copy operations on the source
file have been completed.
For a copy only involving one server (the source and destination are
on the same server), this operation is unnecessary.
If the server supports COPY_NOTIFY, the server is REQUIRED to support
the OFFLOAD_REVOKE operation.
14.5. Operation 63: OFFLOAD_STATUS - Poll for status of a server-side
copy
14.5.1. ARGUMENT
struct OFFLOAD_STATUS4args {
/* CURRENT_FH: destination file */
stateid4 osa_stateid;
};
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14.5.2. RESULT
struct OFFLOAD_STATUS4resok {
length4 osr_bytes_copied;
nfsstat4 osr_complete<1>;
};
union OFFLOAD_STATUS4res switch (nfsstat4 osr_status) {
case NFS4_OK:
OFFLOAD_STATUS4resok osr_resok4;
default:
void;
};
14.5.3. DESCRIPTION
OFFLOAD_STATUS is used for both intra- and inter-server asynchronous
copies. The OFFLOAD_STATUS operation allows the client to poll the
destination server to determine the status of an asynchronous copy
operation.
If this operation is successful, the number of bytes copied are
returned to the client in the osr_bytes_copied field. The
osr_bytes_copied value indicates the number of bytes copied but not
which specific bytes have been copied.
If the optional osr_complete field is present, the copy has
completed. In this case the status value indicates the result of the
asynchronous copy operation. In all cases, the server will also
deliver the final results of the asynchronous copy in a CB_OFFLOAD
operation.
The failure of this operation does not indicate the result of the
asynchronous copy in any way.
If the server supports asynchronous copies, the server is REQUIRED to
support the OFFLOAD_STATUS operation.
14.6. Modification to Operation 42: EXCHANGE_ID - Instantiate Client ID
14.6.1. ARGUMENT
/* new */
const EXCHGID4_FLAG_SUPP_FENCE_OPS = 0x00000004;
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14.6.2. RESULT
Unchanged
14.6.3. MOTIVATION
Enterprise applications require guarantees that an operation has
either aborted or completed. NFSv4.1 provides this guarantee as long
as the session is alive: simply send a SEQUENCE operation on the same
slot with a new sequence number, and the successful return of
SEQUENCE indicates the previous operation has completed. However, if
the session is lost, there is no way to know when any in progress
operations have aborted or completed. In hindsight, the NFSv4.1
specification should have mandated that DESTROY_SESSION either abort
or complete all outstanding operations.
14.6.4. DESCRIPTION
A client SHOULD request the EXCHGID4_FLAG_SUPP_FENCE_OPS capability
when it sends an EXCHANGE_ID operation. The server SHOULD set this
capability in the EXCHANGE_ID reply whether the client requests it or
not. It is the server's return that determines whether this
capability is in effect. When it is in effect, the following will
occur:
o The server will not reply to any DESTROY_SESSION invoked with the
client ID until all operations in progress are completed or
aborted.
o The server will not reply to subsequent EXCHANGE_ID invoked on the
same client owner with a new verifier until all operations in
progress on the client ID's session are completed or aborted.
o The NFS server SHOULD support client ID trunking, and if it does
and the EXCHGID4_FLAG_SUPP_FENCE_OPS capability is enabled, then a
session ID created on one node of the storage cluster MUST be
destroyable via DESTROY_SESSION. In addition, DESTROY_CLIENTID
and an EXCHANGE_ID with a new verifier affects all sessions
regardless what node the sessions were created on.
14.7. Operation 64: WRITE_PLUS
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14.7.1. ARGUMENT
struct data_info4 {
offset4 di_offset;
length4 di_length;
bool di_allocated;
};
struct data4 {
offset4 d_offset;
bool d_allocated;
opaque d_data<>;
};
union write_plus_arg4 switch (data_content4 wpa_content) {
case NFS4_CONTENT_DATA:
data4 wpa_data;
case NFS4_CONTENT_APP_DATA_HOLE:
app_data_hole4 wpa_adh;
case NFS4_CONTENT_HOLE:
data_info4 wpa_hole;
default:
void;
};
struct WRITE_PLUS4args {
/* CURRENT_FH: file */
stateid4 wp_stateid;
stable_how4 wp_stable;
write_plus_arg4 wp_data<>;
};
14.7.2. RESULT
struct write_response4 {
stateid4 wr_callback_id<1>;
count4 wr_count;
stable_how4 wr_committed;
verifier4 wr_writeverf;
};
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union WRITE_PLUS4res switch (nfsstat4 wp_status) {
case NFS4_OK:
write_response4 wp_resok4;
default:
void;
};
14.7.3. DESCRIPTION
The WRITE_PLUS operation is an extension of the NFSv4.1 WRITE
operation (see Section 18.2 of [RFC5661] and writes data to the
regular file identified by the current filehandle. The server MAY
write fewer bytes than requested by the client.
The WRITE_PLUS argument is comprised of an array of rpr_contents,
each of which describe a data_content4 type of data (Section 7.1.2).
For NFSv4.2, the allowed values are data, ADH, and hole. The array
contents MUST be contiguous in the file. A successful WRITE_PLUS
will construct a reply for wr_count, wr_committed, and wr_writeverf
as per the NFSv4.1 WRITE operation results. If wr_callback_id is
set, it indicates an asynchronous reply (see Section 14.7.3.4).
WRITE_PLUS has to support all of the errors which are returned by
WRITE plus NFS4ERR_UNION_NOTSUPP. If the client asks for a hole and
the server does not support that arm of the discriminated union, but
does support one or more additional arms, it can signal to the client
that it supports the operation, but not the arm with
NFS4ERR_UNION_NOTSUPP.
If the client supports WRITE_PLUS and any arm of the discriminated
union other than NFS4_CONTENT_DATA, it MUST support CB_OFFLOAD.
14.7.3.1. Data
The d_offset specifies the offset where the data should be written.
An d_offset of zero specifies that the write should start at the
beginning of the file. The d_count, as encoded as part of the opaque
data parameter, represents the number of bytes of data that are to be
written. If the d_count is zero, the WRITE_PLUS will succeed and
return a d_count of zero subject to permissions checking.
Note that d_allocated has no meaning for WRITE_PLUS.
The data MUST be written synchronously and MUST follow the same
semantics of COMMIT as does the WRITE operation.
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14.7.3.2. Hole punching
Whenever a client wishes to zero the blocks backing a particular
region in the file, it calls the WRITE_PLUS operation with the
current filehandle set to the filehandle of the file in question, and
the equivalent of start offset and length in bytes of the region set
in wpa_hole.di_offset and wpa_hole.di_length respectively. If the
wpa_hole.di_allocated is set to TRUE, then the blocks will be zeroed
and if it is set to FALSE, then they will be deallocated. All
further reads to this region MUST return zeros until overwritten.
The filehandle specified must be that of a regular file.
Situations may arise where di_offset and/or di_offset + di_length
will not be aligned to a boundary that the server does allocations/
deallocations in. For most file systems, this is the block size of
the file system. In such a case, the server can deallocate as many
bytes as it can in the region. The blocks that cannot be deallocated
MUST be zeroed. Except for the block deallocation and maximum hole
punching capability, a WRITE_PLUS operation is to be treated similar
to a write of zeroes.
The server is not required to complete deallocating the blocks
specified in the operation before returning. The server SHOULD
return an asynchronous result if it can determine the operation will
be long running (see Section 14.7.3.4).
If used to hole punch, WRITE_PLUS will result in the space_used
attribute being decreased by the number of bytes that were
deallocated. The space_freed attribute may or may not decrease,
depending on the support and whether the blocks backing the specified
range were shared or not. The size attribute will remain unchanged.
The WRITE_PLUS operation MUST NOT change the space reservation
guarantee of the file. While the server can deallocate the blocks
specified by di_offset and di_length, future writes to this region
MUST NOT fail with NFSERR_NOSPC.
14.7.3.3. ADHs
If the server supports ADHs, then it MUST support the
NFS4_CONTENT_APP_DATA_HOLE arm of the WRITE_PLUS operation. The
server has no concept of the structure imposed by the application.
It is only when the application writes to a section of the file does
order get imposed. In order to detect corruption even before the
application utilizes the file, the application will want to
initialize a range of ADHs using WRITE_PLUS.
For ADHs, when the client invokes the WRITE_PLUS operation, it has
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two desired results:
1. The structure described by the app_data_block4 be imposed on the
file.
2. The contents described by the app_data_block4 be sparse.
If the server supports the WRITE_PLUS operation, it still might not
support sparse files. So if it receives the WRITE_PLUS operation,
then it MUST populate the contents of the file with the initialized
ADHs. The server SHOULD return an asynchronous result if it can
determine the operation will be long running (see Section 14.7.3.4).
If the data was already initialized, there are two interesting
scenarios:
1. The data blocks are allocated.
2. Initializing in the middle of an existing ADH.
If the data blocks were already allocated, then the WRITE_PLUS is a
hole punch operation. If WRITE_PLUS supports sparse files, then the
data blocks are to be deallocated. If not, then the data blocks are
to be rewritten in the indicated ADH format.
Since the server has no knowledge of ADHs, it should not report
misaligned creation of ADHs. Even while it can detect them, it
cannot disallow them, as the application might be in the process of
changing the size of the ADHs. Thus the server must be prepared to
handle an WRITE_PLUS into an existing ADH.
This document does not mandate the manner in which the server stores
ADHs sparsely for a file. However, if an WRITE_PLUS arrives that
will force a new ADH to start inside an existing ADH then the server
will have three ADHs instead of two. It will have one up to the new
one for the WRITE_PLUS, one for the WRITE_PLUS, and one for after the
WRITE_PLUS. Note that depending on server specific policies for
block allocation, there may also be some physical blocks allocated to
align the boundaries.
14.7.3.4. Asynchronous Transactions
Both hole punching and ADH initialization may lead to server
determining to service the operation asynchronously. If it decides
to do so, it sets the stateid in wr_callback_id to be that of the
wp_stateid. If it does not set the wr_callback_id, then the result
is synchronous.
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When the client determines that the reply will be given
asynchronously, it should not assume anything about the contents of
what it wrote until it is informed by the server that the operation
is complete. It can use OFFLOAD_STATUS (Section 14.5) to monitor the
operation and OFFLOAD_ABORT (Section 14.2) to cancel the operation.
An example of a asynchronous WRITE_PLUS is shown in Figure 6. Note
that as with the COPY operation, WRITE_PLUS must provide a stateid
for tracking the asynchronous operation.
Client Server
+ +
| |
|--- OPEN ---------------------------->| Client opens
|<------------------------------------/| the file
| |
|--- WRITE_PLUS ---------------------->| Client punches
|<------------------------------------/| a hole
| |
| |
|--- OFFLOAD_STATUS ------------------>| Client may poll
|<------------------------------------/| for status
| |
| . | Multiple OFFLOAD_STATUS
| . | operations may be sent.
| . |
| |
|<-- CB_OFFLOAD -----------------------| Server reports results
|\------------------------------------>|
| |
|--- CLOSE --------------------------->| Client closes
|<------------------------------------/| the file
| |
| |
Figure 6: An asynchronous WRITE_PLUS.
When CB_OFFLOAD informs the client of the successful WRITE_PLUS, the
write_response4 embedded in the operation will provide the necessary
information that a synchronous WRITE_PLUS would have provided.
Regardless of whether the operation is asynchronous or synchronous,
it MUST still support the COMMIT operation semantics as outlined in
Section 18.3 of [RFC5661]. I.e., COMMIT works on one or more WRITE
operations and the WRITE_PLUS operation can appear as several WRITE
operations to the server. The client can use locking operations to
control the behavior on the server with respect to long running
asynchronous write operations.
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14.8. Operation 67: IO_ADVISE - Application I/O access pattern hints
14.8.1. ARGUMENT
enum IO_ADVISE_type4 {
IO_ADVISE4_NORMAL = 0,
IO_ADVISE4_SEQUENTIAL = 1,
IO_ADVISE4_SEQUENTIAL_BACKWARDS = 2,
IO_ADVISE4_RANDOM = 3,
IO_ADVISE4_WILLNEED = 4,
IO_ADVISE4_WILLNEED_OPPORTUNISTIC = 5,
IO_ADVISE4_DONTNEED = 6,
IO_ADVISE4_NOREUSE = 7,
IO_ADVISE4_READ = 8,
IO_ADVISE4_WRITE = 9,
IO_ADVISE4_INIT_PROXIMITY = 10
};
struct IO_ADVISE4args {
/* CURRENT_FH: file */
stateid4 iar_stateid;
offset4 iar_offset;
length4 iar_count;
bitmap4 iar_hints;
};
14.8.2. RESULT
struct IO_ADVISE4resok {
bitmap4 ior_hints;
};
union IO_ADVISE4res switch (nfsstat4 _status) {
case NFS4_OK:
IO_ADVISE4resok resok4;
default:
void;
};
14.8.3. DESCRIPTION
The IO_ADVISE operation sends an I/O access pattern hint to the
server for the owner of the stateid for a given byte range specified
by iar_offset and iar_count. The byte range specified by iar_offset
and iar_count need not currently exist in the file, but the iar_hints
will apply to the byte range when it does exist. If iar_count is 0,
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all data following iar_offset is specified. The server MAY ignore
the advice.
The following are the allowed hints for a stateid holder:
IO_ADVISE4_NORMAL There is no advice to give, this is the default
behavior.
IO_ADVISE4_SEQUENTIAL Expects to access the specified data
sequentially from lower offsets to higher offsets.
IO_ADVISE4_SEQUENTIAL_BACKWARDS Expects to access the specified data
sequentially from higher offsets to lower offsets.
IO_ADVISE4_RANDOM Expects to access the specified data in a random
order.
IO_ADVISE4_WILLNEED Expects to access the specified data in the near
future.
IO_ADVISE4_WILLNEED_OPPORTUNISTIC Expects to possibly access the
data in the near future. This is a speculative hint, and
therefore the server should prefetch data or indirect blocks only
if it can be done at a marginal cost.
IO_ADVISE_DONTNEED Expects that it will not access the specified
data in the near future.
IO_ADVISE_NOREUSE Expects to access the specified data once and then
not reuse it thereafter.
IO_ADVISE4_READ Expects to read the specified data in the near
future.
IO_ADVISE4_WRITE Expects to write the specified data in the near
future.
IO_ADVISE4_INIT_PROXIMITY Informs the server that the data in the
byte range remains important to the client.
Since IO_ADVISE is a hint, a server SHOULD NOT return an error and
invalidate a entire Compound request if one of the sent hints in
iar_hints is not supported by the server. Also, the server MUST NOT
return an error if the client sends contradictory hints to the
server, e.g., IO_ADVISE4_SEQUENTIAL and IO_ADVISE4_RANDOM in a single
IO_ADVISE operation. In these cases, the server MUST return success
and a ior_hints value that indicates the hint it intends to
implement. This may mean simply returning IO_ADVISE4_NORMAL.
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The ior_hints returned by the server is primarily for debugging
purposes since the server is under no obligation to carry out the
hints that it describes in the ior_hints result. In addition, while
the server may have intended to implement the hints returned in
ior_hints, as time progresses, the server may need to change its
handling of a given file due to several reasons including, but not
limited to, memory pressure, additional IO_ADVISE hints sent by other
clients, and heuristically detected file access patterns.
The server MAY return different advice than what the client
requested. If it does, then this might be due to one of several
conditions, including, but not limited to another client advising of
a different I/O access pattern; a different I/O access pattern from
another client that that the server has heuristically detected; or
the server is not able to support the requested I/O access pattern,
perhaps due to a temporary resource limitation.
Each issuance of the IO_ADVISE operation overrides all previous
issuances of IO_ADVISE for a given byte range. This effectively
follows a strategy of last hint wins for a given stateid and byte
range.
Clients should assume that hints included in an IO_ADVISE operation
will be forgotten once the file is closed.
14.8.4. IMPLEMENTATION
The NFS client may choose to issue an IO_ADVISE operation to the
server in several different instances.
The most obvious is in direct response to an application's execution
of posix_fadvise(). In this case, IO_ADVISE4_WRITE and
IO_ADVISE4_READ may be set based upon the type of file access
specified when the file was opened.
14.8.5. IO_ADVISE4_INIT_PROXIMITY
The IO_ADVISE4_INIT_PROXIMITY hint is non-posix in origin and conveys
that the client has recently accessed the byte range in its own
cache. I.e., it has not accessed it on the server, but it has
locally. When the server reaches resource exhaustion, knowing which
data is more important allows the server to make better choices about
which data to, for example purge from a cache, or move to secondary
storage. It also informs the server which delegations are more
important, since if delegations are working correctly, once delegated
to a client and the client has read the content for that byte range,
a server might never receive another read request for that byte
range.
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This hint is also useful in the case of NFS clients which are network
booting from a server. If the first client to be booted sends this
hint, then it keeps the cache warm for the remaining clients.
14.8.6. pNFS File Layout Data Type Considerations
The IO_ADVISE considerations for pNFS are very similar to the COMMIT
considerations for pNFS. That is, as with COMMIT, some NFS server
implementations prefer IO_ADVISE be done on the DS, and some prefer
it be done on the MDS.
So for the file's layout type, it is proposed that NFSv4.2 include an
additional hint NFL42_CARE_IO_ADVISE_THRU_MDS which is valid only on
NFSv4.2 or higher. Any file's layout obtained with NFSv4.1 MUST NOT
have NFL42_UFLG_IO_ADVISE_THRU_MDS set. Any file's layout obtained
with NFSv4.2 MAY have NFL42_UFLG_IO_ADVISE_THRU_MDS set. If the
client does not implement IO_ADVISE, then it MUST ignore
NFL42_UFLG_IO_ADVISE_THRU_MDS.
If NFL42_UFLG_IO_ADVISE_THRU_MDS is set, the client MUST send the
IO_ADVISE operation to the MDS in order for it to be honored by the
DS. Once the MDS receives the IO_ADVISE operation, it will
communicate the advice to each DS.
If NFL42_UFLG_IO_ADVISE_THRU_MDS is not set, then the client SHOULD
send an IO_ADVISE operation to the appropriate DS for the specified
byte range. While the client MAY always send IO_ADVISE to the MDS,
if the server has not set NFL42_UFLG_IO_ADVISE_THRU_MDS, the client
should expect that such an IO_ADVISE is futile. Note that a client
SHOULD use the same set of arguments on each IO_ADVISE sent to a DS
for the same open file reference.
The server is not required to support different advice for different
DS's with the same open file reference.
14.8.6.1. Dense and Sparse Packing Considerations
The IO_ADVISE operation MUST use the iar_offset and byte range as
dictated by the presence or absence of NFL4_UFLG_DENSE.
E.g., if NFL4_UFLG_DENSE is present, and a READ or WRITE to the DS
for iar_offset 0 really means iar_offset 10000 in the logical file,
then an IO_ADVISE for iar_offset 0 means iar_offset 10000.
E.g., if NFL4_UFLG_DENSE is absent, then a READ or WRITE to the DS
for iar_offset 0 really means iar_offset 0 in the logical file, then
an IO_ADVISE for iar_offset 0 means iar_offset 0 in the logical file.
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E.g., if NFL4_UFLG_DENSE is present, the stripe unit is 1000 bytes
and the stripe count is 10, and the dense DS file is serving
iar_offset 0. A READ or WRITE to the DS for iar_offsets 0, 1000,
2000, and 3000, really mean iar_offsets 10000, 20000, 30000, and
40000 (implying a stripe count of 10 and a stripe unit of 1000), then
an IO_ADVISE sent to the same DS with an iar_offset of 500, and a
iar_count of 3000 means that the IO_ADVISE applies to these byte
ranges of the dense DS file:
- 500 to 999
- 1000 to 1999
- 2000 to 2999
- 3000 to 3499
I.e., the contiguous range 500 to 3499 as specified in IO_ADVISE.
It also applies to these byte ranges of the logical file:
- 10500 to 10999 (500 bytes)
- 20000 to 20999 (1000 bytes)
- 30000 to 30999 (1000 bytes)
- 40000 to 40499 (500 bytes)
(total 3000 bytes)
E.g., if NFL4_UFLG_DENSE is absent, the stripe unit is 250 bytes, the
stripe count is 4, and the sparse DS file is serving iar_offset 0.
Then a READ or WRITE to the DS for iar_offsets 0, 1000, 2000, and
3000, really mean iar_offsets 0, 1000, 2000, and 3000 in the logical
file, keeping in mind that on the DS file,. byte ranges 250 to 999,
1250 to 1999, 2250 to 2999, and 3250 to 3999 are not accessible.
Then an IO_ADVISE sent to the same DS with an iar_offset of 500, and
a iar_count of 3000 means that the IO_ADVISE applies to these byte
ranges of the logical file and the sparse DS file:
- 500 to 999 (500 bytes) - no effect
- 1000 to 1249 (250 bytes) - effective
- 1250 to 1999 (750 bytes) - no effect
- 2000 to 2249 (250 bytes) - effective
- 2250 to 2999 (750 bytes) - no effect
- 3000 to 3249 (250 bytes) - effective
- 3250 to 3499 (250 bytes) - no effect
(subtotal 2250 bytes) - no effect
(subtotal 750 bytes) - effective
(grand total 3000 bytes) - no effect + effective
If neither of the flags NFL42_UFLG_IO_ADVISE_THRU_MDS and
NFL4_UFLG_DENSE are set in the layout, then any IO_ADVISE request
sent to the data server with a byte range that overlaps stripe unit
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that the data server does not serve MUST NOT result in the status
NFS4ERR_PNFS_IO_HOLE. Instead, the response SHOULD be successful and
if the server applies IO_ADVISE hints on any stripe units that
overlap with the specified range, those hints SHOULD be indicated in
the response.
14.9. Changes to Operation 51: LAYOUTRETURN
14.9.1. Introduction
In the pNFS description provided in [RFC5661], the client is not
capable to relay an error code from the DS to the MDS. In the
specification of the Objects-Based Layout protocol [RFC5664], use is
made of the opaque lrf_body field of the LAYOUTRETURN argument to do
such a relaying of error codes. In this section, we define a new
data structure to enable the passing of error codes back to the MDS
and provide some guidelines on what both the client and MDS should
expect in such circumstances.
There are two broad classes of errors, transient and persistent. The
client SHOULD strive to only use this new mechanism to report
persistent errors. It MUST be able to deal with transient issues by
itself. Also, while the client might consider an issue to be
persistent, it MUST be prepared for the MDS to consider such issues
to be transient. A prime example of this is if the MDS fences off a
client from either a stateid or a filehandle. The client will get an
error from the DS and might relay either NFS4ERR_ACCESS or
NFS4ERR_BAD_STATEID back to the MDS, with the belief that this is a
hard error. If the MDS is informed by the client that there is an
error, it can safely ignore that. For it, the mission is
accomplished in that the client has returned a layout that the MDS
had most likely recalled.
The client might also need to inform the MDS that it cannot reach one
or more of the DSes. While the MDS can detect the connectivity of
both of these paths:
o MDS to DS
o MDS to client
it cannot determine if the client and DS path is working. As with
the case of the DS passing errors to the client, it must be prepared
for the MDS to consider such outages as being transitory.
The existing LAYOUTRETURN operation is extended by introducing a new
data structure to report errors, layoutreturn_device_error4. Also,
layoutreturn_device_error4 is introduced to enable an array of errors
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to be reported.
14.9.2. ARGUMENT
The ARGUMENT specification of the LAYOUTRETURN operation in section
18.44.1 of [RFC5661] is augmented by the following XDR code
[RFC4506]:
struct layoutreturn_device_error4 {
deviceid4 lrde_deviceid;
nfsstat4 lrde_status;
nfs_opnum4 lrde_opnum;
};
struct layoutreturn_error_report4 {
layoutreturn_device_error4 lrer_errors<>;
};
14.9.3. RESULT
The RESULT of the LAYOUTRETURN operation is unchanged; see section
18.44.2 of [RFC5661].
14.9.4. DESCRIPTION
The following text is added to the end of the LAYOUTRETURN operation
DESCRIPTION in section 18.44.3 of [RFC5661].
When a client uses LAYOUTRETURN with a type of LAYOUTRETURN4_FILE,
then if the lrf_body field is NULL, it indicates to the MDS that the
client experienced no errors. If lrf_body is non-NULL, then the
field references error information which is layout type specific.
I.e., the Objects-Based Layout protocol can continue to utilize
lrf_body as specified in [RFC5664]. For both Files-Based and Block-
Based Layouts, the field references a layoutreturn_device_error4,
which contains an array of layoutreturn_device_error4.
Each individual layoutreturn_device_error4 describes a single error
associated with a DS, which is identified via lrde_deviceid. The
operation which returned the error is identified via lrde_opnum.
Finally the NFS error value (nfsstat4) encountered is provided via
lrde_status and may consist of the following error codes:
NFS4ERR_NXIO: The client was unable to establish any communication
with the DS.
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NFS4ERR_*: The client was able to establish communication with the
DS and is returning one of the allowed error codes for the
operation denoted by lrde_opnum.
14.9.5. IMPLEMENTATION
The following text is added to the end of the LAYOUTRETURN operation
IMPLEMENTATION in section 18.4.4 of [RFC5661].
Clients are expected to tolerate transient storage device errors, and
hence clients SHOULD NOT use the LAYOUTRETURN error handling for
device access problems that may be transient. The methods by which a
client decides whether a device access problem is transient vs.
persistent are implementation-specific, but may include retrying I/Os
to a data server under appropriate conditions.
When an I/O fails to a storage device, the client SHOULD retry the
failed I/O via the MDS. In this situation, before retrying the I/O,
the client SHOULD return the layout, or the affected portion thereof,
and SHOULD indicate which storage device or devices was problematic.
The client needs to do this when the DS is being unresponsive in
order to fence off any failed write attempts, and ensure that they do
not end up overwriting any later data being written through the MDS.
If the client does not do this, the MDS MAY issue a layout recall
callback in order to perform the retried I/O.
The client needs to be cognizant that since this error handling is
optional in the MDS, the MDS may silently ignore this functionality.
Also, as the MDS may consider some issues the client reports to be
expected (see Section 14.9.1), the client might find it difficult to
detect a MDS which has not implemented error handling via
LAYOUTRETURN.
If an MDS is aware that a storage device is proving problematic to a
client, the MDS SHOULD NOT include that storage device in any pNFS
layouts sent to that client. If the MDS is aware that a storage
device is affecting many clients, then the MDS SHOULD NOT include
that storage device in any pNFS layouts sent out. If a client asks
for a new layout for the file from the MDS, it MUST be prepared for
the MDS to return that storage device in the layout. The MDS might
not have any choice in using the storage device, i.e., there might
only be one possible layout for the system. Also, in the case of
existing files, the MDS might have no choice in which storage devices
to hand out to clients.
The MDS is not required to indefinitely retain per-client storage
device error information. An MDS is also not required to
automatically reinstate use of a previously problematic storage
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device; administrative intervention may be required instead.
14.10. Operation 65: READ_PLUS
14.10.1. ARGUMENT
struct READ_PLUS4args {
/* CURRENT_FH: file */
stateid4 rpa_stateid;
offset4 rpa_offset;
count4 rpa_count;
};
14.10.2. RESULT
struct data_info4 {
offset4 di_offset;
length4 di_length;
bool di_allocated;
};
struct data4 {
offset4 d_offset;
bool d_allocated;
opaque d_data<>;
};
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union read_plus_content switch (data_content4 rpc_content) {
case NFS4_CONTENT_DATA:
data4 rpc_data;
case NFS4_CONTENT_APP_DATA_HOLE:
app_data_hole4 rpc_adh;
case NFS4_CONTENT_HOLE:
data_info4 rpc_hole;
default:
void;
};
/*
* Allow a return of an array of contents.
*/
struct read_plus_res4 {
bool rpr_eof;
read_plus_content rpr_contents<>;
};
union READ_PLUS4res switch (nfsstat4 rp_status) {
case NFS4_OK:
read_plus_res4 rp_resok4;
default:
void;
};
14.10.3. DESCRIPTION
The READ_PLUS operation is based upon the NFSv4.1 READ operation (see
Section 18.22 of [RFC5661]) and similarly reads data from the regular
file identified by the current filehandle.
The client provides a rpa_offset of where the READ_PLUS is to start
and a rpa_count of how many bytes are to be read. A rpa_offset of
zero means to read data starting at the beginning of the file. If
rpa_offset is greater than or equal to the size of the file, the
status NFS4_OK is returned with di_length (the data length) set to
zero and eof set to TRUE.
The READ_PLUS result is comprised of an array of rpr_contents, each
of which describe a data_content4 type of data (Section 7.1.2). For
NFSv4.2, the allowed values are data, ADH, and hole. A server is
required to support the data type, but neither ADH nor hole. Both an
ADH and a hole must be returned in its entirety - clients must be
prepared to get more information than they requested. Both the start
and the end of the hole may exceed what was requested. The array
contents MUST be contiguous in the file.
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READ_PLUS has to support all of the errors which are returned by READ
plus NFS4ERR_UNION_NOTSUPP. If the client asks for a hole and the
server does not support that arm of the discriminated union, but does
support one or more additional arms, it can signal to the client that
it supports the operation, but not the arm with
NFS4ERR_UNION_NOTSUPP.
If the data to be returned is comprised entirely of zeros, then the
server may elect to return that data as a hole. The server
differentiates this to the client by setting di_allocated to TRUE in
this case. Note that in such a scenario, the server is not required
to determine the full extent of the "hole" - it does not need to
determine where the zeros start and end. If the server elects to
return the hole as data, then it can set the d_allocted to FALSE in
the rpc_data to indicate it is a hole.
The server may elect to return adjacent elements of the same type.
For example, the guard pattern or block size of an ADH might change,
which would require adjacent elements of type ADH. Likewise if the
server has a range of data comprised entirely of zeros and then a
hole, it might want to return two adjacent holes to the client.
If the client specifies a rpa_count value of zero, the READ_PLUS
succeeds and returns zero bytes of data. In all situations, the
server may choose to return fewer bytes than specified by the client.
The client needs to check for this condition and handle the condition
appropriately.
If the client specifies an rpa_offset and rpa_count value that is
entirely contained within a hole of the file, then the di_offset and
di_length returned must be for the entire hole. This result is
considered valid until the file is changed (detected via the change
attribute). The server MUST provide the same semantics for the hole
as if the client read the region and received zeroes; the implied
holes contents lifetime MUST be exactly the same as any other read
data.
If the client specifies an rpa_offset and rpa_count value that begins
in a non-hole of the file but extends into hole the server should
return an array comprised of both data and a hole. The client MUST
be prepared for the server to return a short read describing just the
data. The client will then issue another READ_PLUS for the remaining
bytes, which the server will respond with information about the hole
in the file.
Except when special stateids are used, the stateid value for a
READ_PLUS request represents a value returned from a previous byte-
range lock or share reservation request or the stateid associated
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with a delegation. The stateid identifies the associated owners if
any and is used by the server to verify that the associated locks are
still valid (e.g., have not been revoked).
If the read ended at the end-of-file (formally, in a correctly formed
READ_PLUS operation, if rpa_offset + rpa_count is equal to the size
of the file), or the READ_PLUS operation extends beyond the size of
the file (if rpa_offset + rpa_count is greater than the size of the
file), eof is returned as TRUE; otherwise, it is FALSE. A successful
READ_PLUS of an empty file will always return eof as TRUE.
If the current filehandle is not an ordinary file, an error will be
returned to the client. In the case that the current filehandle
represents an object of type NF4DIR, NFS4ERR_ISDIR is returned. If
the current filehandle designates a symbolic link, NFS4ERR_SYMLINK is
returned. In all other cases, NFS4ERR_WRONG_TYPE is returned.
For a READ_PLUS with a stateid value of all bits equal to zero, the
server MAY allow the READ_PLUS to be serviced subject to mandatory
byte-range locks or the current share deny modes for the file. For a
READ_PLUS with a stateid value of all bits equal to one, the server
MAY allow READ_PLUS operations to bypass locking checks at the
server.
On success, the current filehandle retains its value.
14.10.4. IMPLEMENTATION
In general, the IMPLEMENTATION notes for READ in Section 18.22.4 of
[RFC5661] also apply to READ_PLUS. One delta is that when the owner
has a locked byte range, the server MUST return an array of
rpr_contents with values inside that range.
14.10.4.1. Additional pNFS Implementation Information
With pNFS, the semantics of using READ_PLUS remains the same. Any
data server MAY return a hole or ADH result for a READ_PLUS request
that it receives. When a data server chooses to return such a
result, it has the option of returning information for the data
stored on that data server (as defined by the data layout), but it
MUST NOT return results for a byte range that includes data managed
by another data server.
A data server should do its best to return as much information about
a ADH as is feasible without having to contact the metadata server.
If communication with the metadata server is required, then every
attempt should be taken to minimize the number of requests.
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If mandatory locking is enforced, then the data server must also
ensure that to return only information that is within the owner's
locked byte range.
14.10.5. READ_PLUS with Sparse Files Example
The following table describes a sparse file. For each byte range,
the file contains either non-zero data or a hole. In addition, the
server in this example uses a Hole Threshold of 32K.
+-------------+----------+
| Byte-Range | Contents |
+-------------+----------+
| 0-15999 | Hole |
| 16K-31999 | Non-Zero |
| 32K-255999 | Hole |
| 256K-287999 | Non-Zero |
| 288K-353999 | Hole |
| 354K-417999 | Non-Zero |
+-------------+----------+
Table 5
Under the given circumstances, if a client was to read from the file
with a max read size of 64K, the following will be the results for
the given READ_PLUS calls. This assumes the client has already
opened the file, acquired a valid stateid ('s' in the example), and
just needs to issue READ_PLUS requests.
1. READ_PLUS(s, 0, 64K) --> NFS_OK, eof = false, <data[0,32K],
hole[32K,224K]>. Since the first hole is less than the server's
Hole Threshhold, the first 32K of the file is returned as data
and the remaining 32K is returned as a hole which actually
extends to 256K.
2. READ_PLUS(s, 32K, 64K) --> NFS_OK, eof = false, <hole[32K,224K]>
The requested range was all zeros, and the current hole begins at
offset 32K and is 224K in length. Note that the client should
not have followed up the previous READ_PLUS request with this one
as the hole information from the previous call extended past what
the client was requesting.
3. READ_PLUS(s, 256K, 64K) --> NFS_OK, eof = false, <data[256K,
288K], hole[288K, 354K]>. Returns an array of the 32K data and
the hole which extends to 354K.
4. READ_PLUS(s, 354K, 64K) --> NFS_OK, eof = true, <data[354K,
418K]>. Returns the final 64K of data and informs the client
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there is no more data in the file.
14.11. Operation 66: SEEK
SEEK is an operation that allows a client to determine the location
of the next data_content4 in a file. It allows an implementation of
the emerging extension to lseek(2) to allow clients to determine
SEEK_HOLE and SEEK_DATA.
14.11.1. ARGUMENT
struct SEEK4args {
/* CURRENT_FH: file */
stateid4 sa_stateid;
offset4 sa_offset;
data_content4 sa_what;
};
14.11.2. RESULT
union seek_content switch (data_content4 content) {
case NFS4_CONTENT_DATA:
data_info4 sc_data;
case NFS4_CONTENT_APP_DATA_HOLE:
app_data_hole4 sc_adh;
case NFS4_CONTENT_HOLE:
data_info4 sc_hole;
default:
void;
};
struct seek_res4 {
bool sr_eof;
seek_content sr_contents;
};
union SEEK4res switch (nfsstat4 status) {
case NFS4_OK:
seek_res4 resok4;
default:
void;
};
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14.11.3. DESCRIPTION
From the given sa_offset, find the next data_content4 of type sa_what
in the file. For either a hole or ADH, this must return the
data_content4 in its entirety. For data, it must not return the
actual data.
SEEK must follow the same rules for stateids as READ_PLUS
(Section 14.10.3).
If the server could not find a corresponding sa_what, then the status
would still be NFS4_OK, but sr_eof would be TRUE. The sr_contents
would contain a zero-ed out content of the appropriate type.
15. NFSv4.2 Callback Operations
15.1. Operation 15: CB_OFFLOAD - Report results of an asynchronous
operation
15.1.1. ARGUMENT
struct write_response4 {
stateid4 wr_callback_id<1>;
count4 wr_count;
stable_how4 wr_committed;
verifier4 wr_writeverf;
};
union offload_info4 switch (nfsstat4 coa_status) {
case NFS4_OK:
write_response4 coa_resok4;
default:
length4 coa_bytes_copied;
};
struct CB_OFFLOAD4args {
nfs_fh4 coa_fh;
stateid4 coa_stateid;
offload_info4 coa_offload_info;
};
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15.1.2. RESULT
struct CB_OFFLOAD4res {
nfsstat4 cor_status;
};
15.1.3. DESCRIPTION
CB_OFFLOAD is used to report to the client the results of an
asynchronous operation, e.g., Server-side Copy or a hole punch. The
coa_fh and coa_stateid identify the transaction and the coa_status
indicates success or failure. The coa_resok4.wr_callback_id MUST NOT
be set. If the transaction failed, then the coa_bytes_copied
contains the number of bytes copied before the failure occurred. The
coa_bytes_copied value indicates the number of bytes copied but not
which specific bytes have been copied.
If the client supports either
1. the COPY operation
2. the WRITE_PLUS operation and any arm of the discriminated union
other than NFS4_CONTENT_DATA
then the client is REQUIRED to support the CB_OFFLOAD operation.
There is a potential race between the reply to the original
transaction on the forechannel and the CB_OFFLOAD callback on the
backchannel. Sections 2.10.6.3 and 20.9.3 of [RFC5661] describe how
to handle this type of issue.
15.1.3.1. Server-side Copy
CB_OFFLOAD is used for both intra- and inter-server asynchronous
copies. This operation is sent by the destination server to the
client in a CB_COMPOUND request. Upon success, the
coa_resok4.wr_count presents the total number of bytes copied.
15.1.3.2. WRITE_PLUS
CB_OFFLOAD is used to report the completion of either a hole punch or
an ADH initialization. Upon success, the coa_resok4 will contain the
same information that a synchronous WRITE_PLUS would have returned.
16. IANA Considerations
This section uses terms that are defined in [RFC5226].
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17. References
17.1. Normative References
[4.2xdr] Haynes, T., "Network File System (NFS) Version 4 Minor
Version 2 External Data Representation Standard (XDR)
Description", March 2013.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005.
[RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File
System (NFS) Version 4 Minor Version 1 Protocol",
RFC 5661, January 2010.
[RFC5664] Halevy, B., Welch, B., and J. Zelenka, "Object-Based
Parallel NFS (pNFS) Operations", RFC 5664, January 2010.
[posix_fadvise]
The Open Group, "Section 'posix_fadvise()' of System
Interfaces of The Open Group Base Specifications Issue 6,
IEEE Std 1003.1, 2004 Edition", 2004.
17.2. Informative References
[Ashdown08]
Ashdown, L., "Chapter 15, Validating Database Files and
Backups, of Oracle Database Backup and Recovery User's
Guide 11g Release 1 (11.1)", August 2008.
[Baira08] Bairavasundaram, L., Goodson, G., Schroeder, B., Arpaci-
Dusseau, A., and R. Arpaci-Dusseau, "An Analysis of Data
Corruption in the Storage Stack", Proceedings of the 6th
USENIX Symposium on File and Storage Technologies (FAST
'08) , 2008.
[FEDFS-ADMIN]
Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M.
Naik, "Administration Protocol for Federated Filesystems",
draft-ietf-nfsv4-federated-fs-admin (Work In Progress),
2010.
[FEDFS-NSDB]
Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M.
Naik, "NSDB Protocol for Federated Filesystems",
draft-ietf-nfsv4-federated-fs-protocol (Work In Progress),
2010.
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[Haynes13]
Haynes, T., "Requirements for Labeled NFS",
draft-ietf-nfsv4-labreqs-04 (work in progress), 2013.
[I-D.ietf-nfsv4-rfc3530bis]
Haynes, T. and D. Noveck, "Network File System (NFS)
version 4 Protocol", draft-ietf-nfsv4-rfc3530bis-25 (Work
In Progress), February 2013.
[IESG08] ISEG, "IESG Processing of RFC Errata for the IETF Stream",
2008.
[MLS] "Section 46.6. Multi-Level Security (MLS) of Deployment
Guide: Deployment, configuration and administration of Red
Hat Enterprise Linux 5, Edition 6", 2011.
[McDougall07]
McDougall, R. and J. Mauro, "Section 11.4.3, Detecting
Memory Corruption of Solaris Internals", 2007.
[Quigley11]
Quigley, D. and J. Lu, "Registry Specification for MAC
Security Label Formats",
draft-quigley-label-format-registry (work in progress),
2011.
[RFC0959] Postel, J. and J. Reynolds, "File Transfer Protocol",
STD 9, RFC 959, October 1985.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC4506] Eisler, M., "XDR: External Data Representation Standard",
RFC 4506, May 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[Strohm11]
Strohm, R., "Chapter 2, Data Blocks, Extents, and
Segments, of Oracle Database Concepts 11g Release 1
(11.1)", January 2011.
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Appendix A. Acknowledgments
For the pNFS Access Permissions Check, the original draft was by
Sorin Faibish, David Black, Mike Eisler, and Jason Glasgow. The work
was influenced by discussions with Benny Halevy and Bruce Fields. A
review was done by Tom Haynes.
For the Sharing change attribute implementation details with NFSv4
clients, the original draft was by Trond Myklebust.
For the NFS Server-side Copy, the original draft was by James
Lentini, Mike Eisler, Deepak Kenchammana, Anshul Madan, and Rahul
Iyer. Tom Talpey co-authored an unpublished version of that
document. It was also was reviewed by a number of individuals:
Pranoop Erasani, Tom Haynes, Arthur Lent, Trond Myklebust, Dave
Noveck, Theresa Lingutla-Raj, Manjunath Shankararao, Satyam Vaghani,
and Nico Williams.
For the NFS space reservation operations, the original draft was by
Mike Eisler, James Lentini, Manjunath Shankararao, and Rahul Iyer.
For the sparse file support, the original draft was by Dean
Hildebrand and Marc Eshel. Valuable input and advice was received
from Sorin Faibish, Bruce Fields, Benny Halevy, Trond Myklebust, and
Richard Scheffenegger.
For the Application IO Hints, the original draft was by Dean
Hildebrand, Mike Eisler, Trond Myklebust, and Sam Falkner. Some
early reviewers included Benny Halevy and Pranoop Erasani.
For Labeled NFS, the original draft was by David Quigley, James
Morris, Jarret Lu, and Tom Haynes. Peter Staubach, Trond Myklebust,
Stephen Smalley, Sorin Faibish, Nico Williams, and David Black also
contributed in the final push to get this accepted.
During the review process, Talia Reyes-Ortiz helped the sessions run
smoothly. While many people contributed here and there, the core
reviewers were Andy Adamson, Pranoop Erasani, Bruce Fields, Chuck
Lever, Trond Myklebust, David Noveck, Peter Staubach, and Mike
Kupfer.
Appendix B. RFC Editor Notes
[RFC Editor: please remove this section prior to publishing this
document as an RFC]
[RFC Editor: prior to publishing this document as an RFC, please
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replace all occurrences of RFCTBD10 with RFCxxxx where xxxx is the
RFC number of this document]
Author's Address
Thomas Haynes (editor)
NetApp
495 E Java Dr
Sunnyvale, CA 95054
USA
Phone: +1 408 419 3018
Email: thomas@netapp.com
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