idnits 2.17.1 draft-ietf-nfsv4-minorversion2-08.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 5 instances of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. == There are 5 instances of lines with private range IPv4 addresses in the document. If these are generic example addresses, they should be changed to use any of the ranges defined in RFC 6890 (or successor): 192.0.2.x, 198.51.100.x or 203.0.113.x. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: Furthermore, each DS MUST not report to a client either a sparse ADB or data which belongs to another DS. One implication of this requirement is that the app_data_block4's adb_block_size MUST be either be the stripe width or the stripe width must be an even multiple of it. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: The second change is to provide a method for the server to notify the client that the attribute changed on an open file on the server. If the file is closed, then during the open attempt, the client will gather the new attribute value. The server MUST not communicate the new value of the attribute, the client MUST query it. This requirement stems from the need for the client to provide sufficient access rights to the attribute. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: When a data server chooses to return a hole result, it has the option of returning hole 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. Data servers that can obtain hole information for the parts of the file stored on that data server, the data server SHOULD return HOLE_INFO and the byte range of the hole stored on that data server. == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (April 25, 2012) is 4382 days in the past. Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: '0' is mentioned on line 3785, but not defined -- Looks like a reference, but probably isn't: '32K' on line 3785 -- Possible downref: Non-RFC (?) normative reference: ref. '1' ** Obsolete normative reference: RFC 5661 (ref. '2') (Obsoleted by RFC 8881) -- Possible downref: Non-RFC (?) normative reference: ref. '3' -- Possible downref: Non-RFC (?) normative reference: ref. '6' == Outdated reference: A later version (-05) exists of draft-ietf-nfsv4-labreqs-00 ** Downref: Normative reference to an Informational draft: draft-ietf-nfsv4-labreqs (ref. '7') == Outdated reference: A later version (-35) exists of draft-ietf-nfsv4-rfc3530bis-09 -- Obsolete informational reference (is this intentional?): RFC 2616 (ref. '13') (Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235) -- Obsolete informational reference (is this intentional?): RFC 5226 (ref. '24') (Obsoleted by RFC 8126) Summary: 2 errors (**), 0 flaws (~~), 10 warnings (==), 8 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NFSv4 T. Haynes 3 Internet-Draft Editor 4 Intended status: Standards Track April 25, 2012 5 Expires: October 27, 2012 7 NFS Version 4 Minor Version 2 8 draft-ietf-nfsv4-minorversion2-08.txt 10 Abstract 12 This Internet-Draft describes NFS version 4 minor version two, 13 focusing mainly on the protocol extensions made from NFS version 4 14 minor version 0 and NFS version 4 minor version 1. Major extensions 15 introduced in NFS version 4 minor version two include: Server-side 16 Copy, Space Reservations, and Support for Sparse Files. 18 Requirements Language 20 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 21 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 22 document are to be interpreted as described in RFC 2119 [1]. 24 Status of this Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on October 27, 2012. 41 Copyright Notice 43 Copyright (c) 2012 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 This document may contain material from IETF Documents or IETF 57 Contributions published or made publicly available before November 58 10, 2008. The person(s) controlling the copyright in some of this 59 material may not have granted the IETF Trust the right to allow 60 modifications of such material outside the IETF Standards Process. 61 Without obtaining an adequate license from the person(s) controlling 62 the copyright in such materials, this document may not be modified 63 outside the IETF Standards Process, and derivative works of it may 64 not be created outside the IETF Standards Process, except to format 65 it for publication as an RFC or to translate it into languages other 66 than English. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6 71 1.1. The NFS Version 4 Minor Version 2 Protocol . . . . . . . 6 72 1.2. Scope of This Document . . . . . . . . . . . . . . . . . 6 73 1.3. NFSv4.2 Goals . . . . . . . . . . . . . . . . . . . . . . 6 74 1.4. Overview of NFSv4.2 Features . . . . . . . . . . . . . . 6 75 1.4.1. Sparse Files . . . . . . . . . . . . . . . . . . . . . 6 76 1.4.2. Application I/O Advise . . . . . . . . . . . . . . . . 7 77 1.5. Differences from NFSv4.1 . . . . . . . . . . . . . . . . 7 78 2. NFS Server-side Copy . . . . . . . . . . . . . . . . . . . . . 7 79 2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 7 80 2.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 8 81 2.2.1. Intra-Server Copy . . . . . . . . . . . . . . . . . . 9 82 2.2.2. Inter-Server Copy . . . . . . . . . . . . . . . . . . 11 83 2.2.3. Server-to-Server Copy Protocol . . . . . . . . . . . . 13 84 2.3. Operations . . . . . . . . . . . . . . . . . . . . . . . 15 85 2.3.1. netloc4 - Network Locations . . . . . . . . . . . . . 15 86 2.3.2. Copy Offload Stateids . . . . . . . . . . . . . . . . 16 87 2.4. Security Considerations . . . . . . . . . . . . . . . . . 16 88 2.4.1. Inter-Server Copy Security . . . . . . . . . . . . . . 16 89 3. Sparse Files . . . . . . . . . . . . . . . . . . . . . . . . . 25 90 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 25 91 3.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 25 92 3.3. Determining the next hole/data . . . . . . . . . . . . . 26 93 4. Space Reservation . . . . . . . . . . . . . . . . . . . . . . 26 94 4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 26 95 5. Support for Application IO Hints . . . . . . . . . . . . . . . 28 96 5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 28 97 5.2. POSIX Requirements . . . . . . . . . . . . . . . . . . . 29 98 5.3. Additional Requirements . . . . . . . . . . . . . . . . . 30 99 5.4. Security Considerations . . . . . . . . . . . . . . . . . 31 100 5.5. IANA Considerations . . . . . . . . . . . . . . . . . . . 31 101 6. Application Data Block Support . . . . . . . . . . . . . . . . 31 102 6.1. Generic Framework . . . . . . . . . . . . . . . . . . . . 32 103 6.1.1. Data Block Representation . . . . . . . . . . . . . . 32 104 6.1.2. Data Content . . . . . . . . . . . . . . . . . . . . . 33 105 6.2. pNFS Considerations . . . . . . . . . . . . . . . . . . . 33 106 6.3. An Example of Detecting Corruption . . . . . . . . . . . 34 107 6.4. Example of READ_PLUS . . . . . . . . . . . . . . . . . . 35 108 6.5. Zero Filled Holes . . . . . . . . . . . . . . . . . . . . 36 109 7. Labeled NFS . . . . . . . . . . . . . . . . . . . . . . . . . 36 110 7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 36 111 7.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 37 112 7.3. MAC Security Attribute . . . . . . . . . . . . . . . . . 37 113 7.3.1. Interpreting FATTR4_SEC_LABEL . . . . . . . . . . . . 38 114 7.3.2. Delegations . . . . . . . . . . . . . . . . . . . . . 39 115 7.3.3. Permission Checking . . . . . . . . . . . . . . . . . 39 116 7.3.4. Object Creation . . . . . . . . . . . . . . . . . . . 40 117 7.3.5. Existing Objects . . . . . . . . . . . . . . . . . . . 40 118 7.3.6. Label Changes . . . . . . . . . . . . . . . . . . . . 40 119 7.4. pNFS Considerations . . . . . . . . . . . . . . . . . . . 41 120 7.5. Discovery of Server LNFS Support . . . . . . . . . . . . 41 121 7.6. MAC Security NFS Modes of Operation . . . . . . . . . . . 42 122 7.6.1. Full Mode . . . . . . . . . . . . . . . . . . . . . . 42 123 7.6.2. Guest Mode . . . . . . . . . . . . . . . . . . . . . . 43 124 7.7. Security Considerations . . . . . . . . . . . . . . . . . 44 125 8. Sharing change attribute implementation details with NFSv4 126 clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 127 8.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 44 128 8.2. Definition of the 'change_attr_type' per-file system 129 attribute . . . . . . . . . . . . . . . . . . . . . . . . 45 130 9. Security Considerations . . . . . . . . . . . . . . . . . . . 46 131 10. Error Values . . . . . . . . . . . . . . . . . . . . . . . . . 46 132 10.1. Error Definitions . . . . . . . . . . . . . . . . . . . . 46 133 10.1.1. General Errors . . . . . . . . . . . . . . . . . . . . 47 134 10.1.2. Server to Server Copy Errors . . . . . . . . . . . . . 47 135 10.1.3. Labeled NFS Errors . . . . . . . . . . . . . . . . . . 47 136 11. File Attributes . . . . . . . . . . . . . . . . . . . . . . . 48 137 11.1. Attribute Definitions . . . . . . . . . . . . . . . . . . 48 138 12. Operations: REQUIRED, RECOMMENDED, or OPTIONAL . . . . . . . . 48 139 13. NFSv4.2 Operations . . . . . . . . . . . . . . . . . . . . . . 52 140 13.1. Operation 59: COPY - Initiate a server-side copy . . . . 52 141 13.2. Operation 60: COPY_ABORT - Cancel a server-side copy . . 59 142 13.3. Operation 61: COPY_NOTIFY - Notify a source server of 143 a future copy . . . . . . . . . . . . . . . . . . . . . . 61 144 13.4. Operation 62: COPY_REVOKE - Revoke a destination 145 server's copy privileges . . . . . . . . . . . . . . . . 63 146 13.5. Operation 63: COPY_STATUS - Poll for status of a 147 server-side copy . . . . . . . . . . . . . . . . . . . . 64 148 13.6. Modification to Operation 42: EXCHANGE_ID - 149 Instantiate Client ID . . . . . . . . . . . . . . . . . . 65 150 13.7. Operation 64: INITIALIZE . . . . . . . . . . . . . . . . 66 151 13.8. Operation 67: IO_ADVISE - Application I/O access 152 pattern hints . . . . . . . . . . . . . . . . . . . . . . 70 153 13.9. Changes to Operation 51: LAYOUTRETURN . . . . . . . . . . 76 154 13.10. Operation 65: READ_PLUS . . . . . . . . . . . . . . . . . 79 155 13.11. Operation 66: SEEK . . . . . . . . . . . . . . . . . . . 85 156 14. NFSv4.2 Callback Operations . . . . . . . . . . . . . . . . . 86 157 14.1. Procedure 16: CB_ATTR_CHANGED - Notify Client that 158 the File's Attributes Changed . . . . . . . . . . . . . . 86 159 14.2. Operation 15: CB_COPY - Report results of a 160 server-side copy . . . . . . . . . . . . . . . . . . . . 87 161 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 88 162 16. References . . . . . . . . . . . . . . . . . . . . . . . . . . 88 163 16.1. Normative References . . . . . . . . . . . . . . . . . . 88 164 16.2. Informative References . . . . . . . . . . . . . . . . . 89 165 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 90 166 Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 91 167 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 91 169 1. Introduction 171 1.1. The NFS Version 4 Minor Version 2 Protocol 173 The NFS version 4 minor version 2 (NFSv4.2) protocol is the third 174 minor version of the NFS version 4 (NFSv4) protocol. The first minor 175 version, NFSv4.0, is described in [10] and the second minor version, 176 NFSv4.1, is described in [2]. It follows the guidelines for minor 177 versioning that are listed in Section 11 of [10]. 179 As a minor version, NFSv4.2 is consistent with the overall goals for 180 NFSv4, but extends the protocol so as to better meet those goals, 181 based on experiences with NFSv4.1. In addition, NFSv4.2 has adopted 182 some additional goals, which motivate some of the major extensions in 183 NFSv4.2. 185 1.2. Scope of This Document 187 This document describes the NFSv4.2 protocol. With respect to 188 NFSv4.0 and NFSv4.1, this document does not: 190 o describe the NFSv4.0 or NFSv4.1 protocols, except where needed to 191 contrast with NFSv4.2. 193 o modify the specification of the NFSv4.0 or NFSv4.1 protocols. 195 o clarify the NFSv4.0 or NFSv4.1 protocols. I.e., any 196 clarifications made here apply to NFSv4.2 and neither of the prior 197 protocols. 199 The full XDR for NFSv4.2 is presented in [3]. 201 1.3. NFSv4.2 Goals 203 [[Comment.1: This needs fleshing out! --TH]] 205 1.4. Overview of NFSv4.2 Features 207 [[Comment.2: This needs fleshing out! --TH]] 209 1.4.1. Sparse Files 211 Two new operations are defined to support the reading of sparse files 212 (READ_PLUS) and the punching of holes to remove backing storage 213 (INITIALIZE). 215 1.4.2. Application I/O Advise 217 We propose a new IO_ADVISE operation for NFSv4.2 that clients can use 218 to communicate expected I/O behavior to the server. By communicating 219 future I/O behavior such as whether a file will be accessed 220 sequentially or randomly, and whether a file will or will not be 221 accessed in the near future, servers can optimize future I/O requests 222 for a file by, for example, prefetching or evicting data. This 223 operation can be used to support the posix_fadvise function as well 224 as other applications such as databases and video editors. 226 1.5. Differences from NFSv4.1 228 In NFSv4.1, the only way to introduce new variants of an operation 229 was to introduce a new operation. I.e., READ becomes either READ2 or 230 READ_PLUS. With the use of discriminated unions as parameters to 231 such functions in NFSv4.2, it is possible to add a new arm in a 232 subsequent minor version. And it is also possible to move such an 233 operation from OPTIONAL/RECOMMENDED to REQUIRED. Forcing an 234 implementation to adopt each arm of a discriminated union at such a 235 time does not meet the spirit of the minor versioning rules. As 236 such, new arms of a discriminated union MUST follow the same 237 guidelines for minor versioning as operations in NFSv4.1 - i.e., they 238 may not be made REQUIRED. To support this, a new error code, 239 NFS4ERR_UNION_NOTSUPP, is introduced which allows the server to 240 communicate to the client that the operation is supported, but the 241 specific arm of the discriminated union is not. 243 2. NFS Server-side Copy 245 2.1. Introduction 247 This section describes a server-side copy feature for the NFS 248 protocol. 250 The server-side copy feature provides a mechanism for the NFS client 251 to perform a file copy on the server without the data being 252 transmitted back and forth over the network. 254 Without this feature, an NFS client copies data from one location to 255 another by reading the data from the server over the network, and 256 then writing the data back over the network to the server. Using 257 this server-side copy operation, the client is able to instruct the 258 server to copy the data locally without the data being sent back and 259 forth over the network unnecessarily. 261 In general, this feature is useful whenever data is copied from one 262 location to another on the server. It is particularly useful when 263 copying the contents of a file from a backup. Backup-versions of a 264 file are copied for a number of reasons, including restoring and 265 cloning data. 267 If the source object and destination object are on different file 268 servers, the file servers will communicate with one another to 269 perform the copy operation. The server-to-server protocol by which 270 this is accomplished is not defined in this document. 272 2.2. Protocol Overview 274 The server-side copy offload operations support both intra-server and 275 inter-server file copies. An intra-server copy is a copy in which 276 the source file and destination file reside on the same server. In 277 an inter-server copy, the source file and destination file are on 278 different servers. In both cases, the copy may be performed 279 synchronously or asynchronously. 281 Throughout the rest of this document, we refer to the NFS server 282 containing the source file as the "source server" and the NFS server 283 to which the file is transferred as the "destination server". In the 284 case of an intra-server copy, the source server and destination 285 server are the same server. Therefore in the context of an intra- 286 server copy, the terms source server and destination server refer to 287 the single server performing the copy. 289 The operations described below are designed to copy files. Other 290 file system objects can be copied by building on these operations or 291 using other techniques. For example if the user wishes to copy a 292 directory, the client can synthesize a directory copy by first 293 creating the destination directory and then copying the source 294 directory's files to the new destination directory. If the user 295 wishes to copy a namespace junction [11] [12], the client can use the 296 ONC RPC Federated Filesystem protocol [12] to perform the copy. 297 Specifically the client can determine the source junction's 298 attributes using the FEDFS_LOOKUP_FSN procedure and create a 299 duplicate junction using the FEDFS_CREATE_JUNCTION procedure. 301 For the inter-server copy protocol, the operations are defined to be 302 compatible with a server-to-server copy protocol in which the 303 destination server reads the file data from the source server. This 304 model in which the file data is pulled from the source by the 305 destination has a number of advantages over a model in which the 306 source pushes the file data to the destination. The advantages of 307 the pull model include: 309 o The pull model only requires a remote server (i.e., the 310 destination server) to be granted read access. A push model 311 requires a remote server (i.e., the source server) to be granted 312 write access, which is more privileged. 314 o The pull model allows the destination server to stop reading if it 315 has run out of space. In a push model, the destination server 316 must flow control the source server in this situation. 318 o The pull model allows the destination server to easily flow 319 control the data stream by adjusting the size of its read 320 operations. In a push model, the destination server does not have 321 this ability. The source server in a push model is capable of 322 writing chunks larger than the destination server has requested in 323 attributes and session parameters. In theory, the destination 324 server could perform a "short" write in this situation, but this 325 approach is known to behave poorly in practice. 327 The following operations are provided to support server-side copy: 329 COPY_NOTIFY: For inter-server copies, the client sends this 330 operation to the source server to notify it of a future file copy 331 from a given destination server for the given user. 333 COPY_REVOKE: Also for inter-server copies, the client sends this 334 operation to the source server to revoke permission to copy a file 335 for the given user. 337 COPY: Used by the client to request a file copy. 339 COPY_ABORT: Used by the client to abort an asynchronous file copy. 341 COPY_STATUS: Used by the client to poll the status of an 342 asynchronous file copy. 344 CB_COPY: Used by the destination server to report the results of an 345 asynchronous file copy to the client. 347 These operations are described in detail in Section 2.3. This 348 section provides an overview of how these operations are used to 349 perform server-side copies. 351 2.2.1. Intra-Server Copy 353 To copy a file on a single server, the client uses a COPY operation. 354 The server may respond to the copy operation with the final results 355 of the copy or it may perform the copy asynchronously and deliver the 356 results using a CB_COPY operation callback. If the copy is performed 357 asynchronously, the client may poll the status of the copy using 358 COPY_STATUS or cancel the copy using COPY_ABORT. 360 A synchronous intra-server copy is shown in Figure 1. In this 361 example, the NFS server chooses to perform the copy synchronously. 362 The copy operation is completed, either successfully or 363 unsuccessfully, before the server replies to the client's request. 364 The server's reply contains the final result of the operation. 366 Client Server 367 + + 368 | | 369 |--- COPY ---------------------------->| Client requests 370 |<------------------------------------/| a file copy 371 | | 372 | | 374 Figure 1: A synchronous intra-server copy. 376 An asynchronous intra-server copy is shown in Figure 2. In this 377 example, the NFS server performs the copy asynchronously. The 378 server's reply to the copy request indicates that the copy operation 379 was initiated and the final result will be delivered at a later time. 380 The server's reply also contains a copy stateid. The client may use 381 this copy stateid to poll for status information (as shown) or to 382 cancel the copy using a COPY_ABORT. When the server completes the 383 copy, the server performs a callback to the client and reports the 384 results. 386 Client Server 387 + + 388 | | 389 |--- COPY ---------------------------->| Client requests 390 |<------------------------------------/| a file copy 391 | | 392 | | 393 |--- COPY_STATUS --------------------->| Client may poll 394 |<------------------------------------/| for status 395 | | 396 | . | Multiple COPY_STATUS 397 | . | operations may be sent. 398 | . | 399 | | 400 |<-- CB_COPY --------------------------| Server reports results 401 |\------------------------------------>| 402 | | 404 Figure 2: An asynchronous intra-server copy. 406 2.2.2. Inter-Server Copy 408 A copy may also be performed between two servers. The copy protocol 409 is designed to accommodate a variety of network topologies. As shown 410 in Figure 3, the client and servers may be connected by multiple 411 networks. In particular, the servers may be connected by a 412 specialized, high speed network (network 192.168.33.0/24 in the 413 diagram) that does not include the client. The protocol allows the 414 client to setup the copy between the servers (over network 415 10.11.78.0/24 in the diagram) and for the servers to communicate on 416 the high speed network if they choose to do so. 418 192.168.33.0/24 419 +-------------------------------------+ 420 | | 421 | | 422 | 192.168.33.18 | 192.168.33.56 423 +-------+------+ +------+------+ 424 | Source | | Destination | 425 +-------+------+ +------+------+ 426 | 10.11.78.18 | 10.11.78.56 427 | | 428 | | 429 | 10.11.78.0/24 | 430 +------------------+------------------+ 431 | 432 | 433 | 10.11.78.243 434 +-----+-----+ 435 | Client | 436 +-----------+ 438 Figure 3: An example inter-server network topology. 440 For an inter-server copy, the client notifies the source server that 441 a file will be copied by the destination server using a COPY_NOTIFY 442 operation. The client then initiates the copy by sending the COPY 443 operation to the destination server. The destination server may 444 perform the copy synchronously or asynchronously. 446 A synchronous inter-server copy is shown in Figure 4. In this case, 447 the destination server chooses to perform the copy before responding 448 to the client's COPY request. 450 An asynchronous copy is shown in Figure 5. In this case, the 451 destination server chooses to respond to the client's COPY request 452 immediately and then perform the copy asynchronously. 454 Client Source Destination 455 + + + 456 | | | 457 |--- COPY_NOTIFY --->| | 458 |<------------------/| | 459 | | | 460 | | | 461 |--- COPY ---------------------------->| 462 | | | 463 | | | 464 | |<----- read -----| 465 | |\--------------->| 466 | | | 467 | | . | Multiple reads may 468 | | . | be necessary 469 | | . | 470 | | | 471 | | | 472 |<------------------------------------/| Destination replies 473 | | | to COPY 475 Figure 4: A synchronous inter-server copy. 477 Client Source Destination 478 + + + 479 | | | 480 |--- COPY_NOTIFY --->| | 481 |<------------------/| | 482 | | | 483 | | | 484 |--- COPY ---------------------------->| 485 |<------------------------------------/| 486 | | | 487 | | | 488 | |<----- read -----| 489 | |\--------------->| 490 | | | 491 | | . | Multiple reads may 492 | | . | be necessary 493 | | . | 494 | | | 495 | | | 496 |--- COPY_STATUS --------------------->| Client may poll 497 |<------------------------------------/| for status 498 | | | 499 | | . | Multiple COPY_STATUS 500 | | . | operations may be sent 501 | | . | 502 | | | 503 | | | 504 | | | 505 |<-- CB_COPY --------------------------| Destination reports 506 |\------------------------------------>| results 507 | | | 509 Figure 5: An asynchronous inter-server copy. 511 2.2.3. Server-to-Server Copy Protocol 513 During an inter-server copy, the destination server reads the file 514 data from the source server. The source server and destination 515 server are not required to use a specific protocol to transfer the 516 file data. The choice of what protocol to use is ultimately the 517 destination server's decision. 519 2.2.3.1. Using NFSv4.x as a Server-to-Server Copy Protocol 521 The destination server MAY use standard NFSv4.x (where x >= 1) to 522 read the data from the source server. If NFSv4.x is used for the 523 server-to-server copy protocol, the destination server can use the 524 filehandle contained in the COPY request with standard NFSv4.x 525 operations to read data from the source server. Specifically, the 526 destination server may use the NFSv4.x OPEN operation's CLAIM_FH 527 facility to open the file being copied and obtain an open stateid. 528 Using the stateid, the destination server may then use NFSv4.x READ 529 operations to read the file. 531 2.2.3.2. Using an alternative Server-to-Server Copy Protocol 533 In a homogeneous environment, the source and destination servers 534 might be able to perform the file copy extremely efficiently using 535 specialized protocols. For example the source and destination 536 servers might be two nodes sharing a common file system format for 537 the source and destination file systems. Thus the source and 538 destination are in an ideal position to efficiently render the image 539 of the source file to the destination file by replicating the file 540 system formats at the block level. Another possibility is that the 541 source and destination might be two nodes sharing a common storage 542 area network, and thus there is no need to copy any data at all, and 543 instead ownership of the file and its contents might simply be re- 544 assigned to the destination. To allow for these possibilities, the 545 destination server is allowed to use a server-to-server copy protocol 546 of its choice. 548 In a heterogeneous environment, using a protocol other than NFSv4.x 549 (e.g,. HTTP [13] or FTP [14]) presents some challenges. In 550 particular, the destination server is presented with the challenge of 551 accessing the source file given only an NFSv4.x filehandle. 553 One option for protocols that identify source files with path names 554 is to use an ASCII hexadecimal representation of the source 555 filehandle as the file name. 557 Another option for the source server is to use URLs to direct the 558 destination server to a specialized service. For example, the 559 response to COPY_NOTIFY could include the URL 560 ftp://s1.example.com:9999/_FH/0x12345, where 0x12345 is the ASCII 561 hexadecimal representation of the source filehandle. When the 562 destination server receives the source server's URL, it would use 563 "_FH/0x12345" as the file name to pass to the FTP server listening on 564 port 9999 of s1.example.com. On port 9999 there would be a special 565 instance of the FTP service that understands how to convert NFS 566 filehandles to an open file descriptor (in many operating systems, 567 this would require a new system call, one which is the inverse of the 568 makefh() function that the pre-NFSv4 MOUNT service needs). 570 Authenticating and identifying the destination server to the source 571 server is also a challenge. Recommendations for how to accomplish 572 this are given in Section 2.4.1.2.4 and Section 2.4.1.4. 574 2.3. Operations 576 In the sections that follow, several operations are defined that 577 together provide the server-side copy feature. These operations are 578 intended to be OPTIONAL operations as defined in section 17 of [2]. 579 The COPY_NOTIFY, COPY_REVOKE, COPY, COPY_ABORT, and COPY_STATUS 580 operations are designed to be sent within an NFSv4 COMPOUND 581 procedure. The CB_COPY operation is designed to be sent within an 582 NFSv4 CB_COMPOUND procedure. 584 Each operation is performed in the context of the user identified by 585 the ONC RPC credential of its containing COMPOUND or CB_COMPOUND 586 request. For example, a COPY_ABORT operation issued by a given user 587 indicates that a specified COPY operation initiated by the same user 588 be canceled. Therefore a COPY_ABORT MUST NOT interfere with a copy 589 of the same file initiated by another user. 591 An NFS server MAY allow an administrative user to monitor or cancel 592 copy operations using an implementation specific interface. 594 2.3.1. netloc4 - Network Locations 596 The server-side copy operations specify network locations using the 597 netloc4 data type shown below: 599 enum netloc_type4 { 600 NL4_NAME = 0, 601 NL4_URL = 1, 602 NL4_NETADDR = 2 603 }; 604 union netloc4 switch (netloc_type4 nl_type) { 605 case NL4_NAME: utf8str_cis nl_name; 606 case NL4_URL: utf8str_cis nl_url; 607 case NL4_NETADDR: netaddr4 nl_addr; 608 }; 610 If the netloc4 is of type NL4_NAME, the nl_name field MUST be 611 specified as a UTF-8 string. The nl_name is expected to be resolved 612 to a network address via DNS, LDAP, NIS, /etc/hosts, or some other 613 means. If the netloc4 is of type NL4_URL, a server URL [4] 614 appropriate for the server-to-server copy operation is specified as a 615 UTF-8 string. If the netloc4 is of type NL4_NETADDR, the nl_addr 616 field MUST contain a valid netaddr4 as defined in Section 3.3.9 of 617 [2]. 619 When netloc4 values are used for an inter-server copy as shown in 620 Figure 3, their values may be evaluated on the source server, 621 destination server, and client. The network environment in which 622 these systems operate should be configured so that the netloc4 values 623 are interpreted as intended on each system. 625 2.3.2. Copy Offload Stateids 627 A server may perform a copy offload operation asynchronously. An 628 asynchronous copy is tracked using a copy offload stateid. Copy 629 offload stateids are included in the COPY, COPY_ABORT, COPY_STATUS, 630 and CB_COPY operations. 632 Section 8.2.4 of [2] specifies that stateids are valid until either 633 (A) the client or server restart or (B) the client returns the 634 resource. 636 A copy offload stateid will be valid until either (A) the client or 637 server restarts or (B) the client returns the resource by issuing a 638 COPY_ABORT operation or the client replies to a CB_COPY operation. 640 A copy offload stateid's seqid MUST NOT be 0 (zero). In the context 641 of a copy offload operation, it is ambiguous to indicate the most 642 recent copy offload operation using a stateid with seqid of 0 (zero). 643 Therefore a copy offload stateid with seqid of 0 (zero) MUST be 644 considered invalid. 646 2.4. Security Considerations 648 The security considerations pertaining to NFSv4 [10] apply to this 649 document. 651 The standard security mechanisms provide by NFSv4 [10] may be used to 652 secure the protocol described in this document. 654 NFSv4 clients and servers supporting the the inter-server copy 655 operations described in this document are REQUIRED to implement [5], 656 including the RPCSEC_GSSv3 privileges copy_from_auth and 657 copy_to_auth. If the server-to-server copy protocol is ONC RPC 658 based, the servers are also REQUIRED to implement the RPCSEC_GSSv3 659 privilege copy_confirm_auth. These requirements to implement are not 660 requirements to use. NFSv4 clients and servers are RECOMMENDED to 661 use [5] to secure server-side copy operations. 663 2.4.1. Inter-Server Copy Security 665 2.4.1.1. Requirements for Secure Inter-Server Copy 667 Inter-server copy is driven by several requirements: 669 o The specification MUST NOT mandate an inter-server copy protocol. 670 There are many ways to copy data. Some will be more optimal than 671 others depending on the identities of the source server and 672 destination server. For example the source and destination 673 servers might be two nodes sharing a common file system format for 674 the source and destination file systems. Thus the source and 675 destination are in an ideal position to efficiently render the 676 image of the source file to the destination file by replicating 677 the file system formats at the block level. In other cases, the 678 source and destination might be two nodes sharing a common storage 679 area network, and thus there is no need to copy any data at all, 680 and instead ownership of the file and its contents simply gets re- 681 assigned to the destination. 683 o The specification MUST provide guidance for using NFSv4.x as a 684 copy protocol. For those source and destination servers willing 685 to use NFSv4.x there are specific security considerations that 686 this specification can and does address. 688 o The specification MUST NOT mandate pre-configuration between the 689 source and destination server. Requiring that the source and 690 destination first have a "copying relationship" increases the 691 administrative burden. However the specification MUST NOT 692 preclude implementations that require pre-configuration. 694 o The specification MUST NOT mandate a trust relationship between 695 the source and destination server. The NFSv4 security model 696 requires mutual authentication between a principal on an NFS 697 client and a principal on an NFS server. This model MUST continue 698 with the introduction of COPY. 700 2.4.1.2. Inter-Server Copy with RPCSEC_GSSv3 702 When the client sends a COPY_NOTIFY to the source server to expect 703 the destination to attempt to copy data from the source server, it is 704 expected that this copy is being done on behalf of the principal 705 (called the "user principal") that sent the RPC request that encloses 706 the COMPOUND procedure that contains the COPY_NOTIFY operation. The 707 user principal is identified by the RPC credentials. A mechanism 708 that allows the user principal to authorize the destination server to 709 perform the copy in a manner that lets the source server properly 710 authenticate the destination's copy, and without allowing the 711 destination to exceed its authorization is necessary. 713 An approach that sends delegated credentials of the client's user 714 principal to the destination server is not used for the following 715 reasons. If the client's user delegated its credentials, the 716 destination would authenticate as the user principal. If the 717 destination were using the NFSv4 protocol to perform the copy, then 718 the source server would authenticate the destination server as the 719 user principal, and the file copy would securely proceed. However, 720 this approach would allow the destination server to copy other files. 721 The user principal would have to trust the destination server to not 722 do so. This is counter to the requirements, and therefore is not 723 considered. Instead an approach using RPCSEC_GSSv3 [5] privileges is 724 proposed. 726 One of the stated applications of the proposed RPCSEC_GSSv3 protocol 727 is compound client host and user authentication [+ privilege 728 assertion]. For inter-server file copy, we require compound NFS 729 server host and user authentication [+ privilege assertion]. The 730 distinction between the two is one without meaning. 732 RPCSEC_GSSv3 introduces the notion of privileges. We define three 733 privileges: 735 copy_from_auth: A user principal is authorizing a source principal 736 ("nfs@") to allow a destination principal ("nfs@ 737 ") to copy a file from the source to the destination. 738 This privilege is established on the source server before the user 739 principal sends a COPY_NOTIFY operation to the source server. 741 struct copy_from_auth_priv { 742 secret4 cfap_shared_secret; 743 netloc4 cfap_destination; 744 /* the NFSv4 user name that the user principal maps to */ 745 utf8str_mixed cfap_username; 746 /* equal to seq_num of rpc_gss_cred_vers_3_t */ 747 unsigned int cfap_seq_num; 748 }; 750 cap_shared_secret is a secret value the user principal generates. 752 copy_to_auth: A user principal is authorizing a destination 753 principal ("nfs@") to allow it to copy a file from 754 the source to the destination. This privilege is established on 755 the destination server before the user principal sends a COPY 756 operation to the destination server. 758 struct copy_to_auth_priv { 759 /* equal to cfap_shared_secret */ 760 secret4 ctap_shared_secret; 761 netloc4 ctap_source; 762 /* the NFSv4 user name that the user principal maps to */ 763 utf8str_mixed ctap_username; 764 /* equal to seq_num of rpc_gss_cred_vers_3_t */ 765 unsigned int ctap_seq_num; 766 }; 768 ctap_shared_secret is a secret value the user principal generated 769 and was used to establish the copy_from_auth privilege with the 770 source principal. 772 copy_confirm_auth: A destination principal is confirming with the 773 source principal that it is authorized to copy data from the 774 source on behalf of the user principal. When the inter-server 775 copy protocol is NFSv4, or for that matter, any protocol capable 776 of being secured via RPCSEC_GSSv3 (i.e., any ONC RPC protocol), 777 this privilege is established before the file is copied from the 778 source to the destination. 780 struct copy_confirm_auth_priv { 781 /* equal to GSS_GetMIC() of cfap_shared_secret */ 782 opaque ccap_shared_secret_mic<>; 783 /* the NFSv4 user name that the user principal maps to */ 784 utf8str_mixed ccap_username; 785 /* equal to seq_num of rpc_gss_cred_vers_3_t */ 786 unsigned int ccap_seq_num; 787 }; 789 2.4.1.2.1. Establishing a Security Context 791 When the user principal wants to COPY a file between two servers, if 792 it has not established copy_from_auth and copy_to_auth privileges on 793 the servers, it establishes them: 795 o The user principal generates a secret it will share with the two 796 servers. This shared secret will be placed in the 797 cfap_shared_secret and ctap_shared_secret fields of the 798 appropriate privilege data types, copy_from_auth_priv and 799 copy_to_auth_priv. 801 o An instance of copy_from_auth_priv is filled in with the shared 802 secret, the destination server, and the NFSv4 user id of the user 803 principal. It will be sent with an RPCSEC_GSS3_CREATE procedure, 804 and so cfap_seq_num is set to the seq_num of the credential of the 805 RPCSEC_GSS3_CREATE procedure. Because cfap_shared_secret is a 806 secret, after XDR encoding copy_from_auth_priv, GSS_Wrap() (with 807 privacy) is invoked on copy_from_auth_priv. The 808 RPCSEC_GSS3_CREATE procedure's arguments are: 810 struct { 811 rpc_gss3_gss_binding *compound_binding; 812 rpc_gss3_chan_binding *chan_binding_mic; 813 rpc_gss3_assertion assertions<>; 814 rpc_gss3_extension extensions<>; 815 } rpc_gss3_create_args; 817 The string "copy_from_auth" is placed in assertions[0].privs. The 818 output of GSS_Wrap() is placed in extensions[0].data. The field 819 extensions[0].critical is set to TRUE. The source server calls 820 GSS_Unwrap() on the privilege, and verifies that the seq_num 821 matches the credential. It then verifies that the NFSv4 user id 822 being asserted matches the source server's mapping of the user 823 principal. If it does, the privilege is established on the source 824 server as: <"copy_from_auth", user id, destination>. The 825 successful reply to RPCSEC_GSS3_CREATE has: 827 struct { 828 opaque handle<>; 829 rpc_gss3_chan_binding *chan_binding_mic; 830 rpc_gss3_assertion granted_assertions<>; 831 rpc_gss3_assertion server_assertions<>; 832 rpc_gss3_extension extensions<>; 833 } rpc_gss3_create_res; 835 The field "handle" is the RPCSEC_GSSv3 handle that the client will 836 use on COPY_NOTIFY requests involving the source and destination 837 server. granted_assertions[0].privs will be equal to 838 "copy_from_auth". The server will return a GSS_Wrap() of 839 copy_to_auth_priv. 841 o An instance of copy_to_auth_priv is filled in with the shared 842 secret, the source server, and the NFSv4 user id. It will be sent 843 with an RPCSEC_GSS3_CREATE procedure, and so ctap_seq_num is set 844 to the seq_num of the credential of the RPCSEC_GSS3_CREATE 845 procedure. Because ctap_shared_secret is a secret, after XDR 846 encoding copy_to_auth_priv, GSS_Wrap() is invoked on 847 copy_to_auth_priv. The RPCSEC_GSS3_CREATE procedure's arguments 848 are: 850 struct { 851 rpc_gss3_gss_binding *compound_binding; 852 rpc_gss3_chan_binding *chan_binding_mic; 853 rpc_gss3_assertion assertions<>; 854 rpc_gss3_extension extensions<>; 855 } rpc_gss3_create_args; 857 The string "copy_to_auth" is placed in assertions[0].privs. The 858 output of GSS_Wrap() is placed in extensions[0].data. The field 859 extensions[0].critical is set to TRUE. After unwrapping, 860 verifying the seq_num, and the user principal to NFSv4 user ID 861 mapping, the destination establishes a privilege of 862 <"copy_to_auth", user id, source>. The successful reply to 863 RPCSEC_GSS3_CREATE has: 865 struct { 866 opaque handle<>; 867 rpc_gss3_chan_binding *chan_binding_mic; 868 rpc_gss3_assertion granted_assertions<>; 869 rpc_gss3_assertion server_assertions<>; 870 rpc_gss3_extension extensions<>; 871 } rpc_gss3_create_res; 873 The field "handle" is the RPCSEC_GSSv3 handle that the client will 874 use on COPY requests involving the source and destination server. 875 The field granted_assertions[0].privs will be equal to 876 "copy_to_auth". The server will return a GSS_Wrap() of 877 copy_to_auth_priv. 879 2.4.1.2.2. Starting a Secure Inter-Server Copy 881 When the client sends a COPY_NOTIFY request to the source server, it 882 uses the privileged "copy_from_auth" RPCSEC_GSSv3 handle. 883 cna_destination_server in COPY_NOTIFY MUST be the same as the name of 884 the destination server specified in copy_from_auth_priv. Otherwise, 885 COPY_NOTIFY will fail with NFS4ERR_ACCESS. The source server 886 verifies that the privilege <"copy_from_auth", user id, destination> 887 exists, and annotates it with the source filehandle, if the user 888 principal has read access to the source file, and if administrative 889 policies give the user principal and the NFS client read access to 890 the source file (i.e., if the ACCESS operation would grant read 891 access). Otherwise, COPY_NOTIFY will fail with NFS4ERR_ACCESS. 893 When the client sends a COPY request to the destination server, it 894 uses the privileged "copy_to_auth" RPCSEC_GSSv3 handle. 895 ca_source_server in COPY MUST be the same as the name of the source 896 server specified in copy_to_auth_priv. Otherwise, COPY will fail 897 with NFS4ERR_ACCESS. The destination server verifies that the 898 privilege <"copy_to_auth", user id, source> exists, and annotates it 899 with the source and destination filehandles. If the client has 900 failed to establish the "copy_to_auth" policy it will reject the 901 request with NFS4ERR_PARTNER_NO_AUTH. 903 If the client sends a COPY_REVOKE to the source server to rescind the 904 destination server's copy privilege, it uses the privileged 905 "copy_from_auth" RPCSEC_GSSv3 handle and the cra_destination_server 906 in COPY_REVOKE MUST be the same as the name of the destination server 907 specified in copy_from_auth_priv. The source server will then delete 908 the <"copy_from_auth", user id, destination> privilege and fail any 909 subsequent copy requests sent under the auspices of this privilege 910 from the destination server. 912 2.4.1.2.3. Securing ONC RPC Server-to-Server Copy Protocols 914 After a destination server has a "copy_to_auth" privilege established 915 on it, and it receives a COPY request, if it knows it will use an ONC 916 RPC protocol to copy data, it will establish a "copy_confirm_auth" 917 privilege on the source server, using nfs@ as the 918 initiator principal, and nfs@ as the target principal. 920 The value of the field ccap_shared_secret_mic is a GSS_VerifyMIC() of 921 the shared secret passed in the copy_to_auth privilege. The field 922 ccap_username is the mapping of the user principal to an NFSv4 user 923 name ("user"@"domain" form), and MUST be the same as ctap_username 924 and cfap_username. The field ccap_seq_num is the seq_num of the 925 RPCSEC_GSSv3 credential used for the RPCSEC_GSS3_CREATE procedure the 926 destination will send to the source server to establish the 927 privilege. 929 The source server verifies the privilege, and establishes a 930 <"copy_confirm_auth", user id, destination> privilege. If the source 931 server fails to verify the privilege, the COPY operation will be 932 rejected with NFS4ERR_PARTNER_NO_AUTH. All subsequent ONC RPC 933 requests sent from the destination to copy data from the source to 934 the destination will use the RPCSEC_GSSv3 handle returned by the 935 source's RPCSEC_GSS3_CREATE response. 937 Note that the use of the "copy_confirm_auth" privilege accomplishes 938 the following: 940 o if a protocol like NFS is being used, with export policies, export 941 policies can be overridden in case the destination server as-an- 942 NFS-client is not authorized 944 o manual configuration to allow a copy relationship between the 945 source and destination is not needed. 947 If the attempt to establish a "copy_confirm_auth" privilege fails, 948 then when the user principal sends a COPY request to destination, the 949 destination server will reject it with NFS4ERR_PARTNER_NO_AUTH. 951 2.4.1.2.4. Securing Non ONC RPC Server-to-Server Copy Protocols 953 If the destination won't be using ONC RPC to copy the data, then the 954 source and destination are using an unspecified copy protocol. The 955 destination could use the shared secret and the NFSv4 user id to 956 prove to the source server that the user principal has authorized the 957 copy. 959 For protocols that authenticate user names with passwords (e.g., HTTP 960 [13] and FTP [14]), the nfsv4 user id could be used as the user name, 961 and an ASCII hexadecimal representation of the RPCSEC_GSSv3 shared 962 secret could be used as the user password or as input into non- 963 password authentication methods like CHAP [15]. 965 2.4.1.3. Inter-Server Copy via ONC RPC but without RPCSEC_GSSv3 967 ONC RPC security flavors other than RPCSEC_GSSv3 MAY be used with the 968 server-side copy offload operations described in this document. In 969 particular, host-based ONC RPC security flavors such as AUTH_NONE and 970 AUTH_SYS MAY be used. If a host-based security flavor is used, a 971 minimal level of protection for the server-to-server copy protocol is 972 possible. 974 In the absence of strong security mechanisms such as RPCSEC_GSSv3, 975 the challenge is how the source server and destination server 976 identify themselves to each other, especially in the presence of 977 multi-homed source and destination servers. In a multi-homed 978 environment, the destination server might not contact the source 979 server from the same network address specified by the client in the 980 COPY_NOTIFY. This can be overcome using the procedure described 981 below. 983 When the client sends the source server the COPY_NOTIFY operation, 984 the source server may reply to the client with a list of target 985 addresses, names, and/or URLs and assign them to the unique 986 quadruple: . If the destination uses one of these target netlocs to contact 988 the source server, the source server will be able to uniquely 989 identify the destination server, even if the destination server does 990 not connect from the address specified by the client in COPY_NOTIFY. 991 The level of assurance in this identification depends on the 992 unpredictability, strength and secrecy of the random number. 994 For example, suppose the network topology is as shown in Figure 3. 995 If the source filehandle is 0x12345, the source server may respond to 996 a COPY_NOTIFY for destination 10.11.78.56 with the URLs: 998 nfs://10.11.78.18//_COPY/FvhH1OKbu8VrxvV1erdjvR7N/10.11.78.56/_FH/ 999 0x12345 1001 nfs://192.168.33.18//_COPY/FvhH1OKbu8VrxvV1erdjvR7N/10.11.78.56/ 1002 _FH/0x12345 1004 The name component after _COPY is 24 characters of base 64, more than 1005 enough to encode a 128 bit random number. 1007 The client will then send these URLs to the destination server in the 1008 COPY operation. Suppose that the 192.168.33.0/24 network is a high 1009 speed network and the destination server decides to transfer the file 1010 over this network. If the destination contacts the source server 1011 from 192.168.33.56 over this network using NFSv4.1, it does the 1012 following: 1014 COMPOUND { PUTROOTFH, LOOKUP "_COPY" ; LOOKUP 1015 "FvhH1OKbu8VrxvV1erdjvR7N" ; LOOKUP "10.11.78.56"; LOOKUP "_FH" ; 1016 OPEN "0x12345" ; GETFH } 1018 Provided that the random number is unpredictable and has been kept 1019 secret by the parties involved, the source server will therefore know 1020 that these NFSv4.x operations are being issued by the destination 1021 server identified in the COPY_NOTIFY. This random number technique 1022 only provides initial authentication of the destination server, and 1023 cannot defend against man-in-the-middle attacks after authentication 1024 or an eavesdropper that observes the random number on the wire. 1025 Other secure communication techniques (e.g., IPsec) are necessary to 1026 block these attacks. 1028 2.4.1.4. Inter-Server Copy without ONC RPC and RPCSEC_GSSv3 1030 The same techniques as Section 2.4.1.3, using unique URLs for each 1031 destination server, can be used for other protocols (e.g., HTTP [13] 1032 and FTP [14]) as well. 1034 3. Sparse Files 1036 3.1. Introduction 1038 A sparse file is a common way of representing a large file without 1039 having to utilize all of the disk space for it. Consequently, a 1040 sparse file uses less physical space than its size indicates. This 1041 means the file contains 'holes', byte ranges within the file that 1042 contain no data. Most modern file systems support sparse files, 1043 including most UNIX file systems and NTFS, but notably not Apple's 1044 HFS+. Common examples of sparse files include Virtual Machine (VM) 1045 OS/disk images, database files, log files, and even checkpoint 1046 recovery files most commonly used by the HPC community. 1048 If an application reads a hole in a sparse file, the file system must 1049 return all zeros to the application. For local data access there is 1050 little penalty, but with NFS these zeroes must be transferred back to 1051 the client. If an application uses the NFS client to read data into 1052 memory, this wastes time and bandwidth as the application waits for 1053 the zeroes to be transferred. 1055 A sparse file is typically created by initializing the file to be all 1056 zeros - nothing is written to the data in the file, instead the hole 1057 is recorded in the metadata for the file. So a 8G disk image might 1058 be represented initially by a couple hundred bits in the inode and 1059 nothing on the disk. If the VM then writes 100M to a file in the 1060 middle of the image, there would now be two holes represented in the 1061 metadata and 100M in the data. 1063 This section introduces a new operation READ_PLUS (Section 13.10) 1064 which supports all the features of READ but includes an extension to 1065 support sparse pattern files. READ_PLUS is guaranteed to perform no 1066 worse than READ, and can dramatically improve performance with sparse 1067 files. READ_PLUS does not depend on pNFS protocol features, but can 1068 be used by pNFS to support sparse files. 1070 3.2. Terminology 1072 Regular file: An object of file type NF4REG or NF4NAMEDATTR. 1074 Sparse file: A Regular file that contains one or more Holes. 1076 Hole: A byte range within a Sparse file that contains regions of all 1077 zeroes. For block-based file systems, this could also be an 1078 unallocated region of the file. 1080 Hole Threshold: The minimum length of a Hole as determined by the 1081 server. If a server chooses to define a Hole Threshold, then it 1082 would not return hole information about holes with a length 1083 shorter than the Hole Threshold. 1085 3.3. Determining the next hole/data 1087 Solaris and ZFS support an extension to lseek(2) that allows 1088 applications to discover holes in a file. The values, SEEK_HOLE and 1089 SEEK_DATA, allow clients to seek to the next hole or beginning of 1090 data, respectively. 1092 4. Space Reservation 1094 4.1. Introduction 1096 This section describes a set of operations that allow applications 1097 such as hypervisors to reserve space for a file, report the amount of 1098 actual disk space a file occupies and freeup the backing space of a 1099 file when it is not required. In virtualized environments, virtual 1100 disk files are often stored on NFS mounted volumes. Since virtual 1101 disk files represent the hard disks of virtual machines, hypervisors 1102 often have to guarantee certain properties for the file. 1104 One such example is space reservation. When a hypervisor creates a 1105 virtual disk file, it often tries to preallocate the space for the 1106 file so that there are no future allocation related errors during the 1107 operation of the virtual machine. Such errors prevent a virtual 1108 machine from continuing execution and result in downtime. 1110 Currently, in order to achieve such a guarantee, applications zero 1111 the entire file. The initial zeroing allocates the backing blocks 1112 and all subsequent writes are overwrites of already allocated blocks. 1113 This approach is not only inefficient in terms of the amount of I/O 1114 done, it is also not guaranteed to work on filesystems that are log 1115 structured or deduplicated. An efficient way of guaranteeing space 1116 reservation would be beneficial to such applications. 1118 If the space_reserved attribute is set on a file, it is guaranteed 1119 that writes that do not grow the file will not fail with 1120 NFSERR_NOSPC. 1122 Another useful feature would be the ability to report the number of 1123 blocks that would be freed when a file is deleted. Currently, NFS 1124 reports two size attributes: 1126 size The logical file size of the file. 1128 space_used The size in bytes that the file occupies on disk 1130 While these attributes are sufficient for space accounting in 1131 traditional filesystems, they prove to be inadequate in modern 1132 filesystems that support block sharing. In such filesystems, 1133 multiple inodes can point to a single block with a block reference 1134 count to guard against premature freeing. Having a way to tell the 1135 number of blocks that would be freed if the file was deleted would be 1136 useful to applications that wish to migrate files when a volume is 1137 low on space. 1139 Since virtual disks represent a hard drive in a virtual machine, a 1140 virtual disk can be viewed as a filesystem within a file. Since not 1141 all blocks within a filesystem are in use, there is an opportunity to 1142 reclaim blocks that are no longer in use. A call to deallocate 1143 blocks could result in better space efficiency. Lesser space MAY be 1144 consumed for backups after block deallocation. 1146 The following operations and attributes can be used to resolve this 1147 issues: 1149 space_reserved This attribute specifies whether the blocks backing 1150 the file have been preallocated. 1152 space_freed This attribute specifies the space freed when a file is 1153 deleted, taking block sharing into consideration. 1155 INITIALIZED This operation zeroes and/or deallocates the blocks 1156 backing a region of the file. 1158 If space_used of a file is interpreted to mean the size in bytes of 1159 all disk blocks pointed to by the inode of the file, then shared 1160 blocks get double counted, over-reporting the space utilization. 1161 This also has the adverse effect that the deletion of a file with 1162 shared blocks frees up less than space_used bytes. 1164 On the other hand, if space_used is interpreted to mean the size in 1165 bytes of those disk blocks unique to the inode of the file, then 1166 shared blocks are not counted in any file, resulting in under- 1167 reporting of the space utilization. 1169 For example, two files A and B have 10 blocks each. Let 6 of these 1170 blocks be shared between them. Thus, the combined space utilized by 1171 the two files is 14 * BLOCK_SIZE bytes. In the former case, the 1172 combined space utilization of the two files would be reported as 20 * 1173 BLOCK_SIZE. However, deleting either would only result in 4 * 1174 BLOCK_SIZE being freed. Conversely, the latter interpretation would 1175 report that the space utilization is only 8 * BLOCK_SIZE. 1177 Adding another size attribute, space_freed, is helpful in solving 1178 this problem. space_freed is the number of blocks that are allocated 1179 to the given file that would be freed on its deletion. In the 1180 example, both A and B would report space_freed as 4 * BLOCK_SIZE and 1181 space_used as 10 * BLOCK_SIZE. If A is deleted, B will report 1182 space_freed as 10 * BLOCK_SIZE as the deletion of B would result in 1183 the deallocation of all 10 blocks. 1185 The addition of this problem doesn't solve the problem of space being 1186 over-reported. However, over-reporting is better than under- 1187 reporting. 1189 5. Support for Application IO Hints 1191 5.1. Introduction 1193 Applications currently have several options for communicating I/O 1194 access patterns to the NFS client. While this can help the NFS 1195 client optimize I/O and caching for a file, it does not allow the NFS 1196 server and its exported file system to do likewise. Therefore, here 1197 we put forth a proposal for the NFSv4.2 protocol to allow 1198 applications to communicate their expected behavior to the server. 1200 By communicating expected access pattern, e.g., sequential or random, 1201 and data re-use behavior, e.g., data range will be read multiple 1202 times and should be cached, the server will be able to better 1203 understand what optimizations it should implement for access to a 1204 file. For example, if a application indicates it will never read the 1205 data more than once, then the file system can avoid polluting the 1206 data cache and not cache the data. 1208 The first application that can issue client I/O hints is the 1209 posix_fadvise operation. For example, on Linux, when an application 1210 uses posix_fadvise to specify a file will be read sequentially, Linux 1211 doubles the readahead buffer size. 1213 Another instance where applications provide an indication of their 1214 desired I/O behavior is the use of direct I/O. By specifying direct 1215 I/O, clients will no longer cache data, but this information is not 1216 passed to the server, which will continue caching data. 1218 Application specific NFS clients such as those used by hypervisors 1219 and databases can also leverage application hints to communicate 1220 their specialized requirements. 1222 This section adds a new IO_ADVISE operation to communicate the client 1223 file access patterns to the NFS server. The NFS server upon 1224 receiving a IO_ADVISE operation MAY choose to alter its I/O and 1225 caching behavior, but is under no obligation to do so. 1227 5.2. POSIX Requirements 1229 The first key requirement of the IO_ADVISE operation is to support 1230 the posix_fadvise function [6], which is supported in Linux and many 1231 other operating systems. Examples and guidance on how to use 1232 posix_fadvise to improve performance can be found here [16]. 1233 posix_fadvise is defined as follows, 1235 int posix_fadvise(int fd, off_t offset, off_t len, int advice); 1237 The posix_fadvise() function shall advise the implementation on the 1238 expected behavior of the application with respect to the data in the 1239 file associated with the open file descriptor, fd, starting at offset 1240 and continuing for len bytes. The specified range need not currently 1241 exist in the file. If len is zero, all data following offset is 1242 specified. The implementation may use this information to optimize 1243 handling of the specified data. The posix_fadvise() function shall 1244 have no effect on the semantics of other operations on the specified 1245 data, although it may affect the performance of other operations. 1247 The advice to be applied to the data is specified by the advice 1248 parameter and may be one of the following values: 1250 POSIX_FADV_NORMAL - Specifies that the application has no advice to 1251 give on its behavior with respect to the specified data. It is 1252 the default characteristic if no advice is given for an open file. 1254 POSIX_FADV_SEQUENTIAL - Specifies that the application expects to 1255 access the specified data sequentially from lower offsets to 1256 higher offsets. 1258 POSIX_FADV_RANDOM - Specifies that the application expects to access 1259 the specified data in a random order. 1261 POSIX_FADV_WILLNEED - Specifies that the application expects to 1262 access the specified data in the near future. 1264 POSIX_FADV_DONTNEED - Specifies that the application expects that it 1265 will not access the specified data in the near future. 1267 POSIX_FADV_NOREUSE - Specifies that the application expects to 1268 access the specified data once and then not reuse it thereafter. 1270 Upon successful completion, posix_fadvise() shall return zero; 1271 otherwise, an error number shall be returned to indicate the error. 1273 5.3. Additional Requirements 1275 Many use cases exist for sending application I/O hints to the server 1276 that cannot utilize the POSIX supported interface. This is because 1277 some applications may benefit from additional hints not specified by 1278 posix_fadvise, and some applications may not use POSIX altogether. 1280 One use case is "Opportunistic Prefetch", which allows a stateid 1281 holder to tell the server that it is possible that it will access the 1282 specified data in the near future. This is similar to 1283 POSIX_FADV_WILLNEED, but the client is unsure it will in fact read 1284 the specified data, so the server should only prefetch the data if it 1285 can be done at a marginal cost. For example, when a server receives 1286 this hint, it could prefetch only the indirect blocks for a file 1287 instead of all the data. This would still improve performance if the 1288 client does read the data, but with less pressure on server memory. 1290 An example use case for this hint is a database that reads in a 1291 single record that points to additional records in either other areas 1292 of the same file or different files located on the same or different 1293 server. While it is likely that the application may access the 1294 additional records, it is far from guaranteed. Therefore, the 1295 database may issue an opportunistic prefetch (instead of 1296 POSIX_FADV_WILLNEED) for the data in the other files pointed to by 1297 the record. 1299 Another use case is "Direct I/O", which allows a stated holder to 1300 inform the server that it does not wish to cache data. Today, for 1301 applications that only intend to read data once, the use of direct 1302 I/O disables client caching, but does not affect server caching. By 1303 caching data that will not be re-read, the server is polluting its 1304 cache and possibly causing useful cached data to be evicted. By 1305 informing the server of its expected I/O access, this situation can 1306 be avoid. Direct I/O can be used in Linux and AIX via the open() 1307 O_DIRECT parameter, in Solaris via the directio() function, and in 1308 Windows via the CreateFile() FILE_FLAG_NO_BUFFERING flag. 1310 Another use case is "Backward Sequential Read", which allows a stated 1311 holder to inform the server that it intends to read the specified 1312 data backwards, i.e., back the end to the beginning. This is 1313 different than POSIX_FADV_SEQUENTIAL, whose implied intention was 1314 that data will be read from beginning to end. This hint allows 1315 servers to prefetch data at the end of the range first, and then 1316 prefetch data sequentially in a backwards manner to the start of the 1317 data range. One example of an application that can make use of this 1318 hint is video editing. 1320 5.4. Security Considerations 1322 None. 1324 5.5. IANA Considerations 1326 The IO_ADVISE_type4 will be extended through an IANA registry. 1328 6. Application Data Block Support 1330 At the OS level, files are contained on disk blocks. Applications 1331 are also free to impose structure on the data contained in a file and 1332 we can define an Application Data Block (ADB) to be such a structure. 1333 From the application's viewpoint, it only wants to handle ADBs and 1334 not raw bytes (see [17]). An ADB is typically comprised of two 1335 sections: a header and data. The header describes the 1336 characteristics of the block and can provide a means to detect 1337 corruption in the data payload. The data section is typically 1338 initialized to all zeros. 1340 The format of the header is application specific, but there are two 1341 main components typically encountered: 1343 1. An ADB Number (ADBN), which allows the application to determine 1344 which data block is being referenced. The ADBN is a logical 1345 block number and is useful when the client is not storing the 1346 blocks in contiguous memory. 1348 2. Fields to describe the state of the ADB and a means to detect 1349 block corruption. For both pieces of data, a useful property is 1350 that allowed values be unique in that if passed across the 1351 network, corruption due to translation between big and little 1352 endian architectures are detectable. For example, 0xF0DEDEF0 has 1353 the same bit pattern in both architectures. 1355 Applications already impose structures on files [17] and detect 1356 corruption in data blocks [18]. What they are not able to do is 1357 efficiently transfer and store ADBs. To initialize a file with ADBs, 1358 the client must send the full ADB to the server and that must be 1359 stored on the server. When the application is initializing a file to 1360 have the ADB structure, it could compress the ADBs to just the 1361 information to necessary to later reconstruct the header portion of 1362 the ADB when the contents are read back. Using sparse file 1363 techniques, the disk blocks described by would not be allocated. 1364 Unlike sparse file techniques, there would be a small cost to store 1365 the compressed header data. 1367 In this section, we are going to define a generic framework for an 1368 ADB, present one approach to detecting corruption in a given ADB 1369 implementation, and describe the model for how the client and server 1370 can support efficient initialization of ADBs, reading of ADB holes, 1371 punching holes in ADBs, and space reservation. Further, we need to 1372 be able to extend this model to applications which do not support 1373 ADBs, but wish to be able to handle sparse files, hole punching, and 1374 space reservation. 1376 6.1. Generic Framework 1378 We want the representation of the ADB to be flexible enough to 1379 support many different applications. The most basic approach is no 1380 imposition of a block at all, which means we are working with the raw 1381 bytes. Such an approach would be useful for storing holes, punching 1382 holes, etc. In more complex deployments, a server might be 1383 supporting multiple applications, each with their own definition of 1384 the ADB. One might store the ADBN at the start of the block and then 1385 have a guard pattern to detect corruption [19]. The next might store 1386 the ADBN at an offset of 100 bytes within the block and have no guard 1387 pattern at all. The point is that existing applications might 1388 already have well defined formats for their data blocks. 1390 The guard pattern can be used to represent the state of the block, to 1391 protect against corruption, or both. Again, it needs to be able to 1392 be placed anywhere within the ADB. 1394 We need to be able to represent the starting offset of the block and 1395 the size of the block. Note that nothing prevents the application 1396 from defining different sized blocks in a file. 1398 6.1.1. Data Block Representation 1400 struct app_data_block4 { 1401 offset4 adb_offset; 1402 length4 adb_block_size; 1403 length4 adb_block_count; 1404 length4 adb_reloff_blocknum; 1405 count4 adb_block_num; 1406 length4 adb_reloff_pattern; 1407 opaque adb_pattern<>; 1408 }; 1409 The app_data_block4 structure captures the abstraction presented for 1410 the ADB. The additional fields present are to allow the transmission 1411 of adb_block_count ADBs at one time. We also use adb_block_num to 1412 convey the ADBN of the first block in the sequence. Each ADB will 1413 contain the same adb_pattern string. 1415 As both adb_block_num and adb_pattern are optional, if either 1416 adb_reloff_pattern or adb_reloff_blocknum is set to NFS4_UINT64_MAX, 1417 then the corresponding field is not set in any of the ADB. 1419 6.1.2. Data Content 1421 /* 1422 * Use an enum such that we can extend new types. 1423 */ 1424 enum data_content4 { 1425 NFS4_CONTENT_DATA = 0, 1426 NFS4_CONTENT_APP_BLOCK = 1, 1427 NFS4_CONTENT_HOLE = 2 1428 }; 1430 New operations might need to differentiate between wanting to access 1431 data versus an ADB. Also, future minor versions might want to 1432 introduce new data formats. This enumeration allows that to occur. 1434 6.2. pNFS Considerations 1436 While this document does not mandate how sparse ADBs are recorded on 1437 the server, it does make the assumption that such information is not 1438 in the file. I.e., the information is metadata. As such, the 1439 INITIALIZE operation is defined to be not supported by the DS - it 1440 must be issued to the MDS. But since the client must not assume a 1441 priori whether a read is sparse or not, the READ_PLUS operation MUST 1442 be supported by both the DS and the MDS. I.e., the client might 1443 impose on the MDS to asynchronously read the data from the DS. 1445 Furthermore, each DS MUST not report to a client either a sparse ADB 1446 or data which belongs to another DS. One implication of this 1447 requirement is that the app_data_block4's adb_block_size MUST be 1448 either be the stripe width or the stripe width must be an even 1449 multiple of it. 1451 The second implication here is that the DS must be able to use the 1452 Control Protocol to determine from the MDS where the sparse ADBs 1453 occur. [[Comment.3: Need to discuss what happens if after the file 1454 is being written to and an INITIALIZE occurs? --TH]] Perhaps instead 1455 of the DS pulling from the MDS, the MDS pushes to the DS? Thus an 1456 INITIALIZE causes a new push? [[Comment.4: Still need to consider 1457 race cases of the DS getting a WRITE and the MDS getting an 1458 INITIALIZE. --TH]] 1460 6.3. An Example of Detecting Corruption 1462 In this section, we define an ADB format in which corruption can be 1463 detected. Note that this is just one possible format and means to 1464 detect corruption. 1466 Consider a very basic implementation of an operating system's disk 1467 blocks. A block is either data or it is an indirect block which 1468 allows for files to be larger than one block. It is desired to be 1469 able to initialize a block. Lastly, to quickly unlink a file, a 1470 block can be marked invalid. The contents remain intact - which 1471 would enable this OS application to undelete a file. 1473 The application defines 4k sized data blocks, with an 8 byte block 1474 counter occurring at offset 0 in the block, and with the guard 1475 pattern occurring at offset 8 inside the block. Furthermore, the 1476 guard pattern can take one of four states: 1478 0xfeedface - This is the FREE state and indicates that the ADB 1479 format has been applied. 1481 0xcafedead - This is the DATA state and indicates that real data 1482 has been written to this block. 1484 0xe4e5c001 - This is the INDIRECT state and indicates that the 1485 block contains block counter numbers that are chained off of this 1486 block. 1488 0xba1ed4a3 - This is the INVALID state and indicates that the block 1489 contains data whose contents are garbage. 1491 Finally, it also defines an 8 byte checksum [20] starting at byte 16 1492 which applies to the remaining contents of the block. If the state 1493 is FREE, then that checksum is trivially zero. As such, the 1494 application has no need to transfer the checksum implicitly inside 1495 the ADB - it need not make the transfer layer aware of the fact that 1496 there is a checksum (see [18] for an example of checksums used to 1497 detect corruption in application data blocks). 1499 Corruption in each ADB can be detected thusly: 1501 o If the guard pattern is anything other than one of the allowed 1502 values, including all zeros. 1504 o If the guard pattern is FREE and any other byte in the remainder 1505 of the ADB is anything other than zero. 1507 o If the guard pattern is anything other than FREE, then if the 1508 stored checksum does not match the computed checksum. 1510 o If the guard pattern is INDIRECT and one of the stored indirect 1511 block numbers has a value greater than the number of ADBs in the 1512 file. 1514 o If the guard pattern is INDIRECT and one of the stored indirect 1515 block numbers is a duplicate of another stored indirect block 1516 number. 1518 As can be seen, the application can detect errors based on the 1519 combination of the guard pattern state and the checksum. But also, 1520 the application can detect corruption based on the state and the 1521 contents of the ADB. This last point is important in validating the 1522 minimum amount of data we incorporated into our generic framework. 1523 I.e., the guard pattern is sufficient in allowing applications to 1524 design their own corruption detection. 1526 Finally, it is important to note that none of these corruption checks 1527 occur in the transport layer. The server and client components are 1528 totally unaware of the file format and might report everything as 1529 being transferred correctly even in the case the application detects 1530 corruption. 1532 6.4. Example of READ_PLUS 1534 The hypothetical application presented in Section 6.3 can be used to 1535 illustrate how READ_PLUS would return an array of results. A file is 1536 created and initialized with 100 4k ADBs in the FREE state: 1538 INITIALIZE {0, 4k, 100, 0, 0, 8, 0xfeedface} 1540 Further, assume the application writes a single ADB at 16k, changing 1541 the guard pattern to 0xcafedead, we would then have in memory: 1543 0 -> (16k - 1) : 4k, 4, 0, 0, 8, 0xfeedface 1544 16k -> (20k - 1) : 00 00 00 05 ca fe de ad XX XX ... XX XX 1545 20k -> 400k : 4k, 95, 0, 6, 0xfeedface 1547 And when the client did a READ_PLUS of 64k at the start of the file, 1548 it would get back a result of an ADB, some data, and a final ADB: 1550 ADB {0, 4, 0, 0, 8, 0xfeedface} 1551 data 4k 1552 ADB {20k, 4k, 59, 0, 6, 0xfeedface} 1554 6.5. Zero Filled Holes 1556 As applications are free to define the structure of an ADB, it is 1557 trivial to define an ADB which supports zero filled holes. Such a 1558 case would encompass the traditional definitions of a sparse file and 1559 hole punching. For example, to punch a 64k hole, starting at 100M, 1560 into an existing file which has no ADB structure: 1562 INITIALIZE {100M, 64k, 1, NFS4_UINT64_MAX, 1563 0, NFS4_UINT64_MAX, 0x0} 1565 7. Labeled NFS 1567 7.1. Introduction 1569 Access control models such as Unix permissions or Access Control 1570 Lists are commonly referred to as Discretionary Access Control (DAC) 1571 models. These systems base their access decisions on user identity 1572 and resource ownership. In contrast Mandatory Access Control (MAC) 1573 models base their access control decisions on the label on the 1574 subject (usually a process) and the object it wishes to access [7]. 1575 These labels may contain user identity information but usually 1576 contain additional information. In DAC systems users are free to 1577 specify the access rules for resources that they own. MAC models 1578 base their security decisions on a system wide policy established by 1579 an administrator or organization which the users do not have the 1580 ability to override. In this section, we add a MAC model to NFSv4. 1582 The first change necessary is to devise a method for transporting and 1583 storing security label data on NFSv4 file objects. Security labels 1584 have several semantics that are met by NFSv4 recommended attributes 1585 such as the ability to set the label value upon object creation. 1586 Access control on these attributes are done through a combination of 1587 two mechanisms. As with other recommended attributes on file objects 1588 the usual DAC checks (ACLs and permission bits) will be performed to 1589 ensure that proper file ownership is enforced. In addition a MAC 1590 system MAY be employed on the client, server, or both to enforce 1591 additional policy on what subjects may modify security label 1592 information. 1594 The second change is to provide a method for the server to notify the 1595 client that the attribute changed on an open file on the server. If 1596 the file is closed, then during the open attempt, the client will 1597 gather the new attribute value. The server MUST not communicate the 1598 new value of the attribute, the client MUST query it. This 1599 requirement stems from the need for the client to provide sufficient 1600 access rights to the attribute. 1602 The final change necessary is a modification to the RPC layer used in 1603 NFSv4 in the form of a new version of the RPCSEC_GSS [8] framework. 1604 In order for an NFSv4 server to apply MAC checks it must obtain 1605 additional information from the client. Several methods were 1606 explored for performing this and it was decided that the best 1607 approach was to incorporate the ability to make security attribute 1608 assertions through the RPC mechanism. RPCSECGSSv3 [5] outlines a 1609 method to assert additional security information such as security 1610 labels on gss context creation and have that data bound to all RPC 1611 requests that make use of that context. 1613 7.2. Definitions 1615 Label Format Specifier (LFS): is an identifier used by the client to 1616 establish the syntactic format of the security label and the 1617 semantic meaning of its components. These specifiers exist in a 1618 registry associated with documents describing the format and 1619 semantics of the label. 1621 Label Format Registry: is the IANA registry containing all 1622 registered LFS along with references to the documents that 1623 describe the syntactic format and semantics of the security label. 1625 Policy Identifier (PI): is an optional part of the definition of a 1626 Label Format Specifier which allows for clients and server to 1627 identify specific security policies. 1629 Object: is a passive resource within the system that we wish to be 1630 protected. Objects can be entities such as files, directories, 1631 pipes, sockets, and many other system resources relevant to the 1632 protection of the system state. 1634 Subject: A subject is an active entity usually a process which is 1635 requesting access to an object. 1637 Multi-Level Security (MLS): is a traditional model where objects are 1638 given a sensitivity level (Unclassified, Secret, Top Secret, etc) 1639 and a category set [21]. 1641 7.3. MAC Security Attribute 1643 MAC models base access decisions on security attributes bound to 1644 subjects and objects. This information can range from a user 1645 identity for an identity based MAC model, sensitivity levels for 1646 Multi-level security, or a type for Type Enforcement. These models 1647 base their decisions on different criteria but the semantics of the 1648 security attribute remain the same. The semantics required by the 1649 security attributes are listed below: 1651 o Must provide flexibility with respect to MAC model. 1653 o Must provide the ability to atomically set security information 1654 upon object creation. 1656 o Must provide the ability to enforce access control decisions both 1657 on the client and the server. 1659 o Must not expose an object to either the client or server name 1660 space before its security information has been bound to it. 1662 NFSv4 implements the security attribute as a recommended attribute. 1663 These attributes have a fixed format and semantics, which conflicts 1664 with the flexible nature of the security attribute. To resolve this 1665 the security attribute consists of two components. The first 1666 component is a LFS as defined in [22] to allow for interoperability 1667 between MAC mechanisms. The second component is an opaque field 1668 which is the actual security attribute data. To allow for various 1669 MAC models NFSv4 should be used solely as a transport mechanism for 1670 the security attribute. It is the responsibility of the endpoints to 1671 consume the security attribute and make access decisions based on 1672 their respective models. In addition, creation of objects through 1673 OPEN and CREATE allows for the security attribute to be specified 1674 upon creation. By providing an atomic create and set operation for 1675 the security attribute it is possible to enforce the second and 1676 fourth requirements. The recommended attribute FATTR4_SEC_LABEL will 1677 be used to satisfy this requirement. 1679 7.3.1. Interpreting FATTR4_SEC_LABEL 1681 The XDR [23] necessary to implement Labeled NFSv4 is presented below: 1683 const FATTR4_SEC_LABEL = 81; 1685 typedef uint32_t policy4; 1687 Figure 6 1689 struct labelformat_spec4 { 1690 policy4 lfs_lfs; 1691 policy4 lfs_pi; 1692 }; 1694 struct sec_label_attr_info { 1695 labelformat_spec4 slai_lfs; 1696 opaque slai_data<>; 1697 }; 1699 The FATTR4_SEC_LABEL contains an array of two components with the 1700 first component being an LFS. It serves to provide the receiving end 1701 with the information necessary to translate the security attribute 1702 into a form that is usable by the endpoint. Label Formats assigned 1703 an LFS may optionally choose to include a Policy Identifier field to 1704 allow for complex policy deployments. The LFS and Label Format 1705 Registry are described in detail in [22]. The translation used to 1706 interpret the security attribute is not specified as part of the 1707 protocol as it may depend on various factors. The second component 1708 is an opaque section which contains the data of the attribute. This 1709 component is dependent on the MAC model to interpret and enforce. 1711 In particular, it is the responsibility of the LFS specification to 1712 define a maximum size for the opaque section, slai_data<>. When 1713 creating or modifying a label for an object, the client needs to be 1714 guaranteed that the server will accept a label that is sized 1715 correctly. By both client and server being part of a specific MAC 1716 model, the client will be aware of the size. 1718 7.3.2. Delegations 1720 In the event that a security attribute is changed on the server while 1721 a client holds a delegation on the file, the client should follow the 1722 existing protocol with respect to attribute changes. It should flush 1723 all changes back to the server and relinquish the delegation. 1725 7.3.3. Permission Checking 1727 It is not feasible to enumerate all possible MAC models and even 1728 levels of protection within a subset of these models. This means 1729 that the NFSv4 client and servers cannot be expected to directly make 1730 access control decisions based on the security attribute. Instead 1731 NFSv4 should defer permission checking on this attribute to the host 1732 system. These checks are performed in addition to existing DAC and 1733 ACL checks outlined in the NFSv4 protocol. Section 7.6 gives a 1734 specific example of how the security attribute is handled under a 1735 particular MAC model. 1737 7.3.4. Object Creation 1739 When creating files in NFSv4 the OPEN and CREATE operations are used. 1740 One of the parameters to these operations is an fattr4 structure 1741 containing the attributes the file is to be created with. This 1742 allows NFSv4 to atomically set the security attribute of files upon 1743 creation. When a client is MAC aware it must always provide the 1744 initial security attribute upon file creation. In the event that the 1745 server is the only MAC aware entity in the system it should ignore 1746 the security attribute specified by the client and instead make the 1747 determination itself. A more in depth explanation can be found in 1748 Section 7.6. 1750 7.3.5. Existing Objects 1752 Note that under the MAC model, all objects must have labels. 1753 Therefore, if an existing server is upgraded to include LNFS support, 1754 then it is the responsibility of the security system to define the 1755 behavior for existing objects. For example, if the security system 1756 is LFS 0, which means the server just stores and returns labels, then 1757 existing files should return labels which are set to an empty value. 1759 7.3.6. Label Changes 1761 As per the requirements, when a file's security label is modified, 1762 the server must notify all clients which have the file opened of the 1763 change in label. It does so with CB_ATTR_CHANGED. There are 1764 preconditions to making an attribute change imposed by NFSv4 and the 1765 security system might want to impose others. In the process of 1766 meeting these preconditions, the server may chose to either serve the 1767 request in whole or return NFS4ERR_DELAY to the SETATTR operation. 1769 If there are open delegations on the file belonging to client other 1770 than the one making the label change, then the process described in 1771 Section 7.3.2 must be followed. 1773 As the server is always presented with the subject label from the 1774 client, it does not necessarily need to communicate the fact that the 1775 label has changed to the client. In the cases where the change 1776 outright denies the client access, the client will be able to quickly 1777 determine that there is a new label in effect. It is in cases where 1778 the client may share the same object between multiple subjects or a 1779 security system which is not strictly hierarchical that the 1780 CB_ATTR_CHANGED callback is very useful. It allows the server to 1781 inform the clients that the cached security attribute is now stale. 1783 Consider a system in which the clients enforce MAC checks and and the 1784 server has a very simple security system which just stores the 1785 labels. In this system, the MAC label check always allows access, 1786 regardless of the subject label. 1788 The way in which MAC labels are enforced is by the client. So if 1789 client A changes a security label on a file, then the server MUST 1790 inform all clients that have the file opened that the label has 1791 changed via CB_ATTR_CHANGED. Then the clients MUST retrieve the new 1792 label and MUST enforce access via the new attribute values. 1794 7.4. pNFS Considerations 1796 This section examines the issues in deploying LNFS in a pNFS 1797 community of servers. 1799 7.4.1. MAC Label Checks 1801 The new FATTR4_SEC_LABEL attribute is metadata information and as 1802 such the DS is not aware of the value contained on the MDS. 1803 Fortunately, the NFSv4.1 protocol [2] already has provisions for 1804 doing access level checks from the DS to the MDS. In order for the 1805 DS to validate the subject label presented by the client, it SHOULD 1806 utilize this mechanism. 1808 If a file's FATTR4_SEC_LABEL is changed, then the MDS should utilize 1809 CB_ATTR_CHANGED to inform the client of that fact. If the MDS is 1810 maintaining 1812 7.5. Discovery of Server LNFS Support 1814 The server can easily determine that a client supports LNFS when it 1815 queries for the FATTR4_SEC_LABEL label for an object. Note that it 1816 cannot assume that the presence of RPCSEC_GSSv3 indicates LNFS 1817 support. The client might need to discover which LFS the server 1818 supports. 1820 A server which supports LNFS MUST allow a client with any subject 1821 label to retrieve the FATTR4_SEC_LABEL attribute for the root 1822 filehandle, ROOTFH. The following compound must always succeed as 1823 far as a MAC label check is concerned: 1825 PUTROOTFH, GETATTR {FATTR4_SEC_LABEL} 1827 Note that the server might have imposed a security flavor on the root 1828 that precludes such access. I.e., if the server requires kerberized 1829 access and the client presents a compound with AUTH_SYS, then the 1830 server is allowed to return NFS4ERR_WRONGSEC in this case. But if 1831 the client presents a correct security flavor, then the server MUST 1832 return the FATTR4_SEC_LABEL attribute with the supported LFS filled 1833 in. 1835 7.6. MAC Security NFS Modes of Operation 1837 A system using Labeled NFS may operate in two modes. The first mode 1838 provides the most protection and is called "full mode". In this mode 1839 both the client and server implement a MAC model allowing each end to 1840 make an access control decision. The remaining mode is called the 1841 "guest mode" and in this mode one end of the connection is not 1842 implementing a MAC model and thus offers less protection than full 1843 mode. 1845 7.6.1. Full Mode 1847 Full mode environments consist of MAC aware NFSv4 servers and clients 1848 and may be composed of mixed MAC models and policies. The system 1849 requires that both the client and server have an opportunity to 1850 perform an access control check based on all relevant information 1851 within the network. The file object security attribute is provided 1852 using the mechanism described in Section 7.3. The security attribute 1853 of the subject making the request is transported at the RPC layer 1854 using the mechanism described in RPCSECGSSv3 [5]. 1856 7.6.1.1. Initial Labeling and Translation 1858 The ability to create a file is an action that a MAC model may wish 1859 to mediate. The client is given the responsibility to determine the 1860 initial security attribute to be placed on a file. This allows the 1861 client to make a decision as to the acceptable security attributes to 1862 create a file with before sending the request to the server. Once 1863 the server receives the creation request from the client it may 1864 choose to evaluate if the security attribute is acceptable. 1866 Security attributes on the client and server may vary based on MAC 1867 model and policy. To handle this the security attribute field has an 1868 LFS component. This component is a mechanism for the host to 1869 identify the format and meaning of the opaque portion of the security 1870 attribute. A full mode environment may contain hosts operating in 1871 several different LFSs. In this case a mechanism for translating the 1872 opaque portion of the security attribute is needed. The actual 1873 translation function will vary based on MAC model and policy and is 1874 out of the scope of this document. If a translation is unavailable 1875 for a given LFS then the request SHOULD be denied. Another recourse 1876 is to allow the host to provide a fallback mapping for unknown 1877 security attributes. 1879 7.6.1.2. Policy Enforcement 1881 In full mode access control decisions are made by both the clients 1882 and servers. When a client makes a request it takes the security 1883 attribute from the requesting process and makes an access control 1884 decision based on that attribute and the security attribute of the 1885 object it is trying to access. If the client denies that access an 1886 RPC call to the server is never made. If however the access is 1887 allowed the client will make a call to the NFS server. 1889 When the server receives the request from the client it extracts the 1890 security attribute conveyed in the RPC request. The server then uses 1891 this security attribute and the attribute of the object the client is 1892 trying to access to make an access control decision. If the server's 1893 policy allows this access it will fulfill the client's request, 1894 otherwise it will return NFS4ERR_ACCESS. 1896 Implementations MAY validate security attributes supplied over the 1897 network to ensure that they are within a set of attributes permitted 1898 from a specific peer, and if not, reject them. Note that a system 1899 may permit a different set of attributes to be accepted from each 1900 peer. 1902 7.6.1.3. Label Aware Only Server 1904 If the LFS is 0, then it indicates a server which is label aware, but 1905 does not enforce policies. Such a server will store and retrieve all 1906 object labels presented by clients, notify the clients of any label 1907 changes via CB_ATTR_CHANGED, but will not restrict access via the 1908 subject label. Instead, it will expect the clients to enforce all 1909 such access locally. 1911 7.6.2. Guest Mode 1913 Guest mode implies that either the client or the server does not 1914 handle labels. If the client is not LNFS aware, then it will not 1915 offer subject labels to the server. The server is the only entity 1916 enforcing policy, and may selectively provide standard NFS services 1917 to clients based on their authentication credentials and/or 1918 associated network attributes (e.g., IP address, network interface). 1919 The level of trust and access extended to a client in this mode is 1920 configuration-specific. If the server is not LNFS aware, then it 1921 will not return object labels to the client. Clients in this 1922 environment are may consist of groups implementing different MAC 1923 model policies. The system requires that all clients in the 1924 environment be responsible for access control checks. 1926 7.7. Security Considerations 1928 This entire document deals with security issues. 1930 Depending on the level of protection the MAC system offers there may 1931 be a requirement to tightly bind the security attribute to the data. 1933 When only one of the client or server enforces labels, it is 1934 important to realize that the other side is not enforcing MAC 1935 protections. Alternate methods might be in use to handle the lack of 1936 MAC support and care should be taken to identify and mitigate threats 1937 from possible tampering outside of these methods. 1939 An example of this is that a server that modifies READDIR or LOOKUP 1940 results based on the client's subject label might want to always 1941 construct the same subject label for a client which does not present 1942 one. This will prevent a non-LNFS client from mixing entries in the 1943 directory cache. 1945 8. Sharing change attribute implementation details with NFSv4 clients 1947 8.1. Introduction 1949 Although both the NFSv4 [10] and NFSv4.1 protocol [2], define the 1950 change attribute as being mandatory to implement, there is little in 1951 the way of guidance. The only feature that is mandated by them is 1952 that the value must change whenever the file data or metadata change. 1954 While this allows for a wide range of implementations, it also leaves 1955 the client with a conundrum: how does it determine which is the most 1956 recent value for the change attribute in a case where several RPC 1957 calls have been issued in parallel? In other words if two COMPOUNDs, 1958 both containing WRITE and GETATTR requests for the same file, have 1959 been issued in parallel, how does the client determine which of the 1960 two change attribute values returned in the replies to the GETATTR 1961 requests corresponds to the most recent state of the file? In some 1962 cases, the only recourse may be to send another COMPOUND containing a 1963 third GETATTR that is fully serialised with the first two. 1965 NFSv4.2 avoids this kind of inefficiency by allowing the server to 1966 share details about how the change attribute is expected to evolve, 1967 so that the client may immediately determine which, out of the 1968 several change attribute values returned by the server, is the most 1969 recent. 1971 8.2. Definition of the 'change_attr_type' per-file system attribute 1973 enum change_attr_typeinfo { 1974 NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR = 0, 1975 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER = 1, 1976 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS = 2, 1977 NFS4_CHANGE_TYPE_IS_TIME_METADATA = 3, 1978 NFS4_CHANGE_TYPE_IS_UNDEFINED = 4 1979 }; 1981 +------------------+----+---------------------------+-----+ 1982 | Name | Id | Data Type | Acc | 1983 +------------------+----+---------------------------+-----+ 1984 | change_attr_type | XX | enum change_attr_typeinfo | R | 1985 +------------------+----+---------------------------+-----+ 1987 The solution enables the NFS server to provide additional information 1988 about how it expects the change attribute value to evolve after the 1989 file data or metadata has changed. 'change_attr_type' is defined as a 1990 new recommended attribute, and takes values from enum 1991 change_attr_typeinfo as follows: 1993 NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR: The change attribute value MUST 1994 monotonically increase for every atomic change to the file 1995 attributes, data or directory contents. 1997 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER: The change attribute value MUST 1998 be incremented by one unit for every atomic change to the file 1999 attributes, data or directory contents. This property is 2000 preserved when writing to pNFS data servers. 2002 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS: The change attribute 2003 value MUST be incremented by one unit for every atomic change to 2004 the file attributes, data or directory contents. In the case 2005 where the client is writing to pNFS data servers, the number of 2006 increments is not guaranteed to exactly match the number of 2007 writes. 2009 NFS4_CHANGE_TYPE_IS_TIME_METADATA: The change attribute is 2010 implemented as suggested in the NFSv4 spec [10] in terms of the 2011 time_metadata attribute. 2013 NFS4_CHANGE_TYPE_IS_UNDEFINED: The change attribute does not take 2014 values that fit into any of these categories. 2016 If either NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR, 2017 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER, or 2018 NFS4_CHANGE_TYPE_IS_TIME_METADATA are set, then the client knows at 2019 the very least that the change attribute is monotonically increasing, 2020 which is sufficient to resolve the question of which value is the 2021 most recent. 2023 If the client sees the value NFS4_CHANGE_TYPE_IS_TIME_METADATA, then 2024 by inspecting the value of the 'time_delta' attribute it additionally 2025 has the option of detecting rogue server implementations that use 2026 time_metadata in violation of the spec. 2028 Finally, if the client sees NFS4_CHANGE_TYPE_IS_VERSION_COUNTER, it 2029 has the ability to predict what the resulting change attribute value 2030 should be after a COMPOUND containing a SETATTR, WRITE, or CREATE. 2031 This again allows it to detect changes made in parallel by another 2032 client. The value NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS permits 2033 the same, but only if the client is not doing pNFS WRITEs. 2035 9. Security Considerations 2037 10. Error Values 2039 NFS error numbers are assigned to failed operations within a Compound 2040 (COMPOUND or CB_COMPOUND) request. A Compound request contains a 2041 number of NFS operations that have their results encoded in sequence 2042 in a Compound reply. The results of successful operations will 2043 consist of an NFS4_OK status followed by the encoded results of the 2044 operation. If an NFS operation fails, an error status will be 2045 entered in the reply and the Compound request will be terminated. 2047 10.1. Error Definitions 2049 Protocol Error Definitions 2051 +--------------------------+--------+------------------+ 2052 | Error | Number | Description | 2053 +--------------------------+--------+------------------+ 2054 | NFS4ERR_BADLABEL | 10093 | Section 10.1.3.1 | 2055 | NFS4ERR_MAC_ACCESS | 10094 | Section 10.1.3.2 | 2056 | NFS4ERR_METADATA_NOTSUPP | 10090 | Section 10.1.2.1 | 2057 | NFS4ERR_OFFLOAD_DENIED | 10091 | Section 10.1.2.2 | 2058 | NFS4ERR_PARTNER_NO_AUTH | 10089 | Section 10.1.2.3 | 2059 | NFS4ERR_PARTNER_NOTSUPP | 10088 | Section 10.1.2.4 | 2060 | NFS4ERR_UNION_NOTSUPP | 10095 | Section 10.1.1.1 | 2061 | NFS4ERR_WRONG_LFS | 10092 | Section 10.1.3.3 | 2062 +--------------------------+--------+------------------+ 2064 Table 1 2066 10.1.1. General Errors 2068 This section deals with errors that are applicable to a broad set of 2069 different purposes. 2071 10.1.1.1. NFS4ERR_UNION_NOTSUPP (Error Code 10095) 2073 One of the arguments to the operation is a discriminated union and 2074 while the server supports the given operation, it does not support 2075 the selected arm of the discriminated union. For an example, see 2076 READ_PLUS (Section 13.10). 2078 10.1.2. Server to Server Copy Errors 2080 These errors deal with the interaction between server to server 2081 copies. 2083 10.1.2.1. NFS4ERR_METADATA_NOTSUPP (Error Code 10090) 2085 The destination file cannot support the same metadata as the source 2086 file. 2088 10.1.2.2. NFS4ERR_OFFLOAD_DENIED (Error Code 10091) 2090 The copy offload operation is supported by both the source and the 2091 destination, but the destination is not allowing it for this file. 2092 If the client sees this error, it should fall back to the normal copy 2093 semantics. 2095 10.1.2.3. NFS4ERR_PARTNER_NO_AUTH (Error Code 10089) 2097 The remote server does not authorize a server-to-server copy offload 2098 operation. This may be due to the client's failure to send the 2099 COPY_NOTIFY operation to the remote server, the remote server 2100 receiving a server-to-server copy offload request after the copy 2101 lease time expired, or for some other permission problem. 2103 10.1.2.4. NFS4ERR_PARTNER_NOTSUPP (Error Code 10088) 2105 The remote server does not support the server-to-server copy offload 2106 protocol. 2108 10.1.3. Labeled NFS Errors 2110 These errors are used in LNFS. 2112 10.1.3.1. NFS4ERR_BADLABEL (Error Code 10093) 2113 10.1.3.2. NFS4ERR_MAC_ACCESS (Error Code 10094) 2115 10.1.3.3. NFS4ERR_WRONG_LFS (Error Code 10092) 2117 11. File Attributes 2119 11.1. Attribute Definitions 2121 11.1.1. Attribute 77: space_reserved 2123 The space_reserve attribute is a read/write attribute of type 2124 boolean. It is a per file attribute. When the space_reserved 2125 attribute is set via SETATTR, the server must ensure that there is 2126 disk space to accommodate every byte in the file before it can return 2127 success. If the server cannot guarantee this, it must return 2128 NFS4ERR_NOSPC. 2130 If the client tries to grow a file which has the space_reserved 2131 attribute set, the server must guarantee that there is disk space to 2132 accommodate every byte in the file with the new size before it can 2133 return success. If the server cannot guarantee this, it must return 2134 NFS4ERR_NOSPC. 2136 It is not required that the server allocate the space to the file 2137 before returning success. The allocation can be deferred, however, 2138 it must be guaranteed that it will not fail for lack of space. 2140 The value of space_reserved can be obtained at any time through 2141 GETATTR. 2143 In order to avoid ambiguity, the space_reserve bit cannot be set 2144 along with the size bit in SETATTR. Increasing the size of a file 2145 with space_reserve set will fail if space reservation cannot be 2146 guaranteed for the new size. If the file size is decreased, space 2147 reservation is only guaranteed for the new size and the extra blocks 2148 backing the file can be released. 2150 11.1.2. Attribute 78: space_freed 2152 space_freed gives the number of bytes freed if the file is deleted. 2153 This attribute is read only and is of type length4. It is a per file 2154 attribute. 2156 12. Operations: REQUIRED, RECOMMENDED, or OPTIONAL 2158 The following tables summarize the operations of the NFSv4.2 protocol 2159 and the corresponding designation of REQUIRED, RECOMMENDED, and 2160 OPTIONAL to implement or MUST NOT implement. The designation of MUST 2161 NOT implement is reserved for those operations that were defined in 2162 either NFSv4.0 or NFSV4.1 and MUST NOT be implemented in NFSv4.2. 2164 For the most part, the REQUIRED, RECOMMENDED, or OPTIONAL designation 2165 for operations sent by the client is for the server implementation. 2166 The client is generally required to implement the operations needed 2167 for the operating environment for which it serves. For example, a 2168 read-only NFSv4.2 client would have no need to implement the WRITE 2169 operation and is not required to do so. 2171 The REQUIRED or OPTIONAL designation for callback operations sent by 2172 the server is for both the client and server. Generally, the client 2173 has the option of creating the backchannel and sending the operations 2174 on the fore channel that will be a catalyst for the server sending 2175 callback operations. A partial exception is CB_RECALL_SLOT; the only 2176 way the client can avoid supporting this operation is by not creating 2177 a backchannel. 2179 Since this is a summary of the operations and their designation, 2180 there are subtleties that are not presented here. Therefore, if 2181 there is a question of the requirements of implementation, the 2182 operation descriptions themselves must be consulted along with other 2183 relevant explanatory text within this either specification or that of 2184 NFSv4.1 [2].. 2186 The abbreviations used in the second and third columns of the table 2187 are defined as follows. 2189 REQ REQUIRED to implement 2191 REC RECOMMEND to implement 2193 OPT OPTIONAL to implement 2195 MNI MUST NOT implement 2197 For the NFSv4.2 features that are OPTIONAL, the operations that 2198 support those features are OPTIONAL, and the server would return 2199 NFS4ERR_NOTSUPP in response to the client's use of those operations. 2200 If an OPTIONAL feature is supported, it is possible that a set of 2201 operations related to the feature become REQUIRED to implement. The 2202 third column of the table designates the feature(s) and if the 2203 operation is REQUIRED or OPTIONAL in the presence of support for the 2204 feature. 2206 The OPTIONAL features identified and their abbreviations are as 2207 follows: 2209 pNFS Parallel NFS 2211 FDELG File Delegations 2213 DDELG Directory Delegations 2215 COPY Server Side Copy 2217 ADB Application Data Blocks 2219 Operations 2221 +----------------------+--------------------+-----------------------+ 2222 | Operation | REQ, REC, OPT, or | Feature (REQ, REC, or | 2223 | | MNI | OPT) | 2224 +----------------------+--------------------+-----------------------+ 2225 | ACCESS | REQ | | 2226 | BACKCHANNEL_CTL | REQ | | 2227 | BIND_CONN_TO_SESSION | REQ | | 2228 | CLOSE | REQ | | 2229 | COMMIT | REQ | | 2230 | COPY | OPT | COPY (REQ) | 2231 | COPY_ABORT | OPT | COPY (REQ) | 2232 | COPY_NOTIFY | OPT | COPY (REQ) | 2233 | COPY_REVOKE | OPT | COPY (REQ) | 2234 | COPY_STATUS | OPT | COPY (REQ) | 2235 | CREATE | REQ | | 2236 | CREATE_SESSION | REQ | | 2237 | DELEGPURGE | OPT | FDELG (REQ) | 2238 | DELEGRETURN | OPT | FDELG, DDELG, pNFS | 2239 | | | (REQ) | 2240 | DESTROY_CLIENTID | REQ | | 2241 | DESTROY_SESSION | REQ | | 2242 | EXCHANGE_ID | REQ | | 2243 | FREE_STATEID | REQ | | 2244 | GETATTR | REQ | | 2245 | GETDEVICEINFO | OPT | pNFS (REQ) | 2246 | GETDEVICELIST | OPT | pNFS (OPT) | 2247 | GETFH | REQ | | 2248 | INITIALIZE | OPT | ADB (REQ) | 2249 | GET_DIR_DELEGATION | OPT | DDELG (REQ) | 2250 | LAYOUTCOMMIT | OPT | pNFS (REQ) | 2251 | LAYOUTGET | OPT | pNFS (REQ) | 2252 | LAYOUTRETURN | OPT | pNFS (REQ) | 2253 | LINK | OPT | | 2254 | LOCK | REQ | | 2255 | LOCKT | REQ | | 2256 | LOCKU | REQ | | 2257 | LOOKUP | REQ | | 2258 | LOOKUPP | REQ | | 2259 | NVERIFY | REQ | | 2260 | OPEN | REQ | | 2261 | OPENATTR | OPT | | 2262 | OPEN_CONFIRM | MNI | | 2263 | OPEN_DOWNGRADE | REQ | | 2264 | PUTFH | REQ | | 2265 | PUTPUBFH | REQ | | 2266 | PUTROOTFH | REQ | | 2267 | READ | OPT | | 2268 | READDIR | REQ | | 2269 | READLINK | OPT | | 2270 | READ_PLUS | OPT | ADB (REQ) | 2271 | RECLAIM_COMPLETE | REQ | | 2272 | RELEASE_LOCKOWNER | MNI | | 2273 | REMOVE | REQ | | 2274 | RENAME | REQ | | 2275 | RENEW | MNI | | 2276 | RESTOREFH | REQ | | 2277 | SAVEFH | REQ | | 2278 | SECINFO | REQ | | 2279 | SECINFO_NO_NAME | REC | pNFS file layout | 2280 | | | (REQ) | 2281 | SEQUENCE | REQ | | 2282 | SETATTR | REQ | | 2283 | SETCLIENTID | MNI | | 2284 | SETCLIENTID_CONFIRM | MNI | | 2285 | SET_SSV | REQ | | 2286 | TEST_STATEID | REQ | | 2287 | VERIFY | REQ | | 2288 | WANT_DELEGATION | OPT | FDELG (OPT) | 2289 | WRITE | REQ | | 2290 +----------------------+--------------------+-----------------------+ 2291 Callback Operations 2293 +-------------------------+-------------------+---------------------+ 2294 | Operation | REQ, REC, OPT, or | Feature (REQ, REC, | 2295 | | MNI | or OPT) | 2296 +-------------------------+-------------------+---------------------+ 2297 | CB_COPY | OPT | COPY (REQ) | 2298 | CB_GETATTR | OPT | FDELG (REQ) | 2299 | CB_LAYOUTRECALL | OPT | pNFS (REQ) | 2300 | CB_NOTIFY | OPT | DDELG (REQ) | 2301 | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | 2302 | CB_NOTIFY_LOCK | OPT | | 2303 | CB_PUSH_DELEG | OPT | FDELG (OPT) | 2304 | CB_RECALL | OPT | FDELG, DDELG, pNFS | 2305 | | | (REQ) | 2306 | CB_RECALL_ANY | OPT | FDELG, DDELG, pNFS | 2307 | | | (REQ) | 2308 | CB_RECALL_SLOT | REQ | | 2309 | CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS (REQ) | 2310 | CB_SEQUENCE | OPT | FDELG, DDELG, pNFS | 2311 | | | (REQ) | 2312 | CB_WANTS_CANCELLED | OPT | FDELG, DDELG, pNFS | 2313 | | | (REQ) | 2314 +-------------------------+-------------------+---------------------+ 2316 13. NFSv4.2 Operations 2318 13.1. Operation 59: COPY - Initiate a server-side copy 2320 13.1.1. ARGUMENT 2322 const COPY4_GUARDED = 0x00000001; 2323 const COPY4_METADATA = 0x00000002; 2325 struct COPY4args { 2326 /* SAVED_FH: source file */ 2327 /* CURRENT_FH: destination file or */ 2328 /* directory */ 2329 offset4 ca_src_offset; 2330 offset4 ca_dst_offset; 2331 length4 ca_count; 2332 uint32_t ca_flags; 2333 component4 ca_destination; 2334 netloc4 ca_source_server<>; 2335 }; 2337 13.1.2. RESULT 2339 union COPY4res switch (nfsstat4 cr_status) { 2340 case NFS4_OK: 2341 stateid4 cr_callback_id<1>; 2342 default: 2343 length4 cr_bytes_copied; 2344 }; 2346 13.1.3. DESCRIPTION 2348 The COPY operation is used for both intra-server and inter-server 2349 copies. In both cases, the COPY is always sent from the client to 2350 the destination server of the file copy. The COPY operation requests 2351 that a file be copied from the location specified by the SAVED_FH 2352 value to the location specified by the combination of CURRENT_FH and 2353 ca_destination. 2355 The SAVED_FH must be a regular file. If SAVED_FH is not a regular 2356 file, the operation MUST fail and return NFS4ERR_WRONG_TYPE. 2358 In order to set SAVED_FH to the source file handle, the compound 2359 procedure requesting the COPY will include a sub-sequence of 2360 operations such as 2362 PUTFH source-fh 2363 SAVEFH 2365 If the request is for a server-to-server copy, the source-fh is a 2366 filehandle from the source server and the compound procedure is being 2367 executed on the destination server. In this case, the source-fh is a 2368 foreign filehandle on the server receiving the COPY request. If 2369 either PUTFH or SAVEFH checked the validity of the filehandle, the 2370 operation would likely fail and return NFS4ERR_STALE. 2372 In order to avoid this problem, the minor version incorporating the 2373 COPY operations will need to make a few small changes in the handling 2374 of existing operations. If a server supports the server-to-server 2375 COPY feature, a PUTFH followed by a SAVEFH MUST NOT return 2376 NFS4ERR_STALE for either operation. These restrictions do not pose 2377 substantial difficulties for servers. The CURRENT_FH and SAVED_FH 2378 may be validated in the context of the operation referencing them and 2379 an NFS4ERR_STALE error returned for an invalid file handle at that 2380 point. 2382 The CURRENT_FH and ca_destination together specify the destination of 2383 the copy operation. If ca_destination is of 0 (zero) length, then 2384 CURRENT_FH specifies the target file. In this case, CURRENT_FH MUST 2385 be a regular file and not a directory. If ca_destination is not of 0 2386 (zero) length, the ca_destination argument specifies the file name to 2387 which the data will be copied within the directory identified by 2388 CURRENT_FH. In this case, CURRENT_FH MUST be a directory and not a 2389 regular file. 2391 If the file named by ca_destination does not exist and the operation 2392 completes successfully, the file will be visible in the file system 2393 namespace. If the file does not exist and the operation fails, the 2394 file MAY be visible in the file system namespace depending on when 2395 the failure occurs and on the implementation of the NFS server 2396 receiving the COPY operation. If the ca_destination name cannot be 2397 created in the destination file system (due to file name 2398 restrictions, such as case or length), the operation MUST fail. 2400 The ca_src_offset is the offset within the source file from which the 2401 data will be read, the ca_dst_offset is the offset within the 2402 destination file to which the data will be written, and the ca_count 2403 is the number of bytes that will be copied. An offset of 0 (zero) 2404 specifies the start of the file. A count of 0 (zero) requests that 2405 all bytes from ca_src_offset through EOF be copied to the 2406 destination. If concurrent modifications to the source file overlap 2407 with the source file region being copied, the data copied may include 2408 all, some, or none of the modifications. The client can use standard 2409 NFS operations (e.g., OPEN with OPEN4_SHARE_DENY_WRITE or mandatory 2410 byte range locks) to protect against concurrent modifications if the 2411 client is concerned about this. If the source file's end of file is 2412 being modified in parallel with a copy that specifies a count of 0 2413 (zero) bytes, the amount of data copied is implementation dependent 2414 (clients may guard against this case by specifying a non-zero count 2415 value or preventing modification of the source file as mentioned 2416 above). 2418 If the source offset or the source offset plus count is greater than 2419 or equal to the size of the source file, the operation will fail with 2420 NFS4ERR_INVAL. The destination offset or destination offset plus 2421 count may be greater than the size of the destination file. This 2422 allows for the client to issue parallel copies to implement 2423 operations such as "cat file1 file2 file3 file4 > dest". 2425 If the destination file is created as a result of this command, the 2426 destination file's size will be equal to the number of bytes 2427 successfully copied. If the destination file already existed, the 2428 destination file's size may increase as a result of this operation 2429 (e.g. if ca_dst_offset plus ca_count is greater than the 2430 destination's initial size). 2432 If the ca_source_server list is specified, then this is an inter- 2433 server copy operation and the source file is on a remote server. The 2434 client is expected to have previously issued a successful COPY_NOTIFY 2435 request to the remote source server. The ca_source_server list 2436 SHOULD be the same as the COPY_NOTIFY response's cnr_source_server 2437 list. If the client includes the entries from the COPY_NOTIFY 2438 response's cnr_source_server list in the ca_source_server list, the 2439 source server can indicate a specific copy protocol for the 2440 destination server to use by returning a URL, which specifies both a 2441 protocol service and server name. Server-to-server copy protocol 2442 considerations are described in Section 2.2.3 and Section 2.4.1. 2444 The ca_flags argument allows the copy operation to be customized in 2445 the following ways using the guarded flag (COPY4_GUARDED) and the 2446 metadata flag (COPY4_METADATA). 2448 If the guarded flag is set and the destination exists on the server, 2449 this operation will fail with NFS4ERR_EXIST. 2451 If the guarded flag is not set and the destination exists on the 2452 server, the behavior is implementation dependent. 2454 If the metadata flag is set and the client is requesting a whole file 2455 copy (i.e., ca_count is 0 (zero)), a subset of the destination file's 2456 attributes MUST be the same as the source file's corresponding 2457 attributes and a subset of the destination file's attributes SHOULD 2458 be the same as the source file's corresponding attributes. The 2459 attributes in the MUST and SHOULD copy subsets will be defined for 2460 each NFS version. 2462 For NFSv4.1, Table 2 and Table 3 list the REQUIRED and RECOMMENDED 2463 attributes respectively. A "MUST" in the "Copy to destination file?" 2464 column indicates that the attribute is part of the MUST copy set. A 2465 "SHOULD" in the "Copy to destination file?" column indicates that the 2466 attribute is part of the SHOULD copy set. 2468 +--------------------+----+---------------------------+ 2469 | Name | Id | Copy to destination file? | 2470 +--------------------+----+---------------------------+ 2471 | supported_attrs | 0 | no | 2472 | type | 1 | MUST | 2473 | fh_expire_type | 2 | no | 2474 | change | 3 | SHOULD | 2475 | size | 4 | MUST | 2476 | link_support | 5 | no | 2477 | symlink_support | 6 | no | 2478 | named_attr | 7 | no | 2479 | fsid | 8 | no | 2480 | unique_handles | 9 | no | 2481 | lease_time | 10 | no | 2482 | rdattr_error | 11 | no | 2483 | filehandle | 19 | no | 2484 | suppattr_exclcreat | 75 | no | 2485 +--------------------+----+---------------------------+ 2487 Table 2 2489 +--------------------+----+---------------------------+ 2490 | Name | Id | Copy to destination file? | 2491 +--------------------+----+---------------------------+ 2492 | acl | 12 | MUST | 2493 | aclsupport | 13 | no | 2494 | archive | 14 | no | 2495 | cansettime | 15 | no | 2496 | case_insensitive | 16 | no | 2497 | case_preserving | 17 | no | 2498 | change_policy | 60 | no | 2499 | chown_restricted | 18 | MUST | 2500 | dacl | 58 | MUST | 2501 | dir_notif_delay | 56 | no | 2502 | dirent_notif_delay | 57 | no | 2503 | fileid | 20 | no | 2504 | files_avail | 21 | no | 2505 | files_free | 22 | no | 2506 | files_total | 23 | no | 2507 | fs_charset_cap | 76 | no | 2508 | fs_layout_type | 62 | no | 2509 | fs_locations | 24 | no | 2510 | fs_locations_info | 67 | no | 2511 | fs_status | 61 | no | 2512 | hidden | 25 | MUST | 2513 | homogeneous | 26 | no | 2514 | layout_alignment | 66 | no | 2515 | layout_blksize | 65 | no | 2516 | layout_hint | 63 | no | 2517 | layout_type | 64 | no | 2518 | maxfilesize | 27 | no | 2519 | maxlink | 28 | no | 2520 | maxname | 29 | no | 2521 | maxread | 30 | no | 2522 | maxwrite | 31 | no | 2523 | mdsthreshold | 68 | no | 2524 | mimetype | 32 | MUST | 2525 | mode | 33 | MUST | 2526 | mode_set_masked | 74 | no | 2527 | mounted_on_fileid | 55 | no | 2528 | no_trunc | 34 | no | 2529 | numlinks | 35 | no | 2530 | owner | 36 | MUST | 2531 | owner_group | 37 | MUST | 2532 | quota_avail_hard | 38 | no | 2533 | quota_avail_soft | 39 | no | 2534 | quota_used | 40 | no | 2535 | rawdev | 41 | no | 2536 | retentevt_get | 71 | MUST | 2537 | retentevt_set | 72 | no | 2538 | retention_get | 69 | MUST | 2539 | retention_hold | 73 | MUST | 2540 | retention_set | 70 | no | 2541 | sacl | 59 | MUST | 2542 | space_avail | 42 | no | 2543 | space_free | 43 | no | 2544 | space_freed | 78 | no | 2545 | space_reserved | 77 | MUST | 2546 | space_total | 44 | no | 2547 | space_used | 45 | no | 2548 | system | 46 | MUST | 2549 | time_access | 47 | MUST | 2550 | time_access_set | 48 | no | 2551 | time_backup | 49 | no | 2552 | time_create | 50 | MUST | 2553 | time_delta | 51 | no | 2554 | time_metadata | 52 | SHOULD | 2555 | time_modify | 53 | MUST | 2556 | time_modify_set | 54 | no | 2557 +--------------------+----+---------------------------+ 2559 Table 3 2561 [NOTE: The source file's attribute values will take precedence over 2562 any attribute values inherited by the destination file.] 2563 In the case of an inter-server copy or an intra-server copy between 2564 file systems, the attributes supported for the source file and 2565 destination file could be different. By definition,the REQUIRED 2566 attributes will be supported in all cases. If the metadata flag is 2567 set and the source file has a RECOMMENDED attribute that is not 2568 supported for the destination file, the copy MUST fail with 2569 NFS4ERR_ATTRNOTSUPP. 2571 Any attribute supported by the destination server that is not set on 2572 the source file SHOULD be left unset. 2574 Metadata attributes not exposed via the NFS protocol SHOULD be copied 2575 to the destination file where appropriate. 2577 The destination file's named attributes are not duplicated from the 2578 source file. After the copy process completes, the client MAY 2579 attempt to duplicate named attributes using standard NFSv4 2580 operations. However, the destination file's named attribute 2581 capabilities MAY be different from the source file's named attribute 2582 capabilities. 2584 If the metadata flag is not set and the client is requesting a whole 2585 file copy (i.e., ca_count is 0 (zero)), the destination file's 2586 metadata is implementation dependent. 2588 If the client is requesting a partial file copy (i.e., ca_count is 2589 not 0 (zero)), the client SHOULD NOT set the metadata flag and the 2590 server MUST ignore the metadata flag. 2592 If the operation does not result in an immediate failure, the server 2593 will return NFS4_OK, and the CURRENT_FH will remain the destination's 2594 filehandle. 2596 If an immediate failure does occur, cr_bytes_copied will be set to 2597 the number of bytes copied to the destination file before the error 2598 occurred. The cr_bytes_copied value indicates the number of bytes 2599 copied but not which specific bytes have been copied. 2601 A return of NFS4_OK indicates that either the operation is complete 2602 or the operation was initiated and a callback will be used to deliver 2603 the final status of the operation. 2605 If the cr_callback_id is returned, this indicates that the operation 2606 was initiated and a CB_COPY callback will deliver the final results 2607 of the operation. The cr_callback_id stateid is termed a copy 2608 stateid in this context. The server is given the option of returning 2609 the results in a callback because the data may require a relatively 2610 long period of time to copy. 2612 If no cr_callback_id is returned, the operation completed 2613 synchronously and no callback will be issued by the server. The 2614 completion status of the operation is indicated by cr_status. 2616 If the copy completes successfully, either synchronously or 2617 asynchronously, the data copied from the source file to the 2618 destination file MUST appear identical to the NFS client. However, 2619 the NFS server's on disk representation of the data in the source 2620 file and destination file MAY differ. For example, the NFS server 2621 might encrypt, compress, deduplicate, or otherwise represent the on 2622 disk data in the source and destination file differently. 2624 In the event of a failure the state of the destination file is 2625 implementation dependent. The COPY operation may fail for the 2626 following reasons (this is a partial list). 2628 o NFS4ERR_MOVED 2630 o NFS4ERR_NOTSUPP 2632 o NFS4ERR_PARTNER_NOTSUPP 2634 o NFS4ERR_OFFLOAD_DENIED 2636 o NFS4ERR_PARTNER_NO_AUTH 2638 o NFS4ERR_FBIG 2640 o NFS4ERR_NOTDIR 2642 o NFS4ERR_WRONG_TYPE 2644 o NFS4ERR_ISDIR 2646 o NFS4ERR_INVAL 2648 o NFS4ERR_DELAY 2650 o NFS4ERR_METADATA_NOTSUPP 2652 o NFS4ERR_WRONGSEC 2654 13.2. Operation 60: COPY_ABORT - Cancel a server-side copy 2655 13.2.1. ARGUMENT 2657 struct COPY_ABORT4args { 2658 /* CURRENT_FH: desination file */ 2659 stateid4 caa_stateid; 2660 }; 2662 13.2.2. RESULT 2664 struct COPY_ABORT4res { 2665 nfsstat4 car_status; 2666 }; 2668 13.2.3. DESCRIPTION 2670 COPY_ABORT is used for both intra- and inter-server asynchronous 2671 copies. The COPY_ABORT operation allows the client to cancel a 2672 server-side copy operation that it initiated. This operation is sent 2673 in a COMPOUND request from the client to the destination server. 2674 This operation may be used to cancel a copy when the application that 2675 requested the copy exits before the operation is completed or for 2676 some other reason. 2678 The request contains the filehandle and copy stateid cookies that act 2679 as the context for the previously initiated copy operation. 2681 The result's car_status field indicates whether the cancel was 2682 successful or not. A value of NFS4_OK indicates that the copy 2683 operation was canceled and no callback will be issued by the server. 2684 A copy operation that is successfully canceled may result in none, 2685 some, or all of the data copied. 2687 If the server supports asynchronous copies, the server is REQUIRED to 2688 support the COPY_ABORT operation. 2690 The COPY_ABORT operation may fail for the following reasons (this is 2691 a partial list): 2693 o NFS4ERR_NOTSUPP 2695 o NFS4ERR_RETRY 2697 o NFS4ERR_COMPLETE_ALREADY 2699 o NFS4ERR_SERVERFAULT 2701 13.3. Operation 61: COPY_NOTIFY - Notify a source server of a future 2702 copy 2704 13.3.1. ARGUMENT 2706 struct COPY_NOTIFY4args { 2707 /* CURRENT_FH: source file */ 2708 netloc4 cna_destination_server; 2709 }; 2711 13.3.2. RESULT 2713 struct COPY_NOTIFY4resok { 2714 nfstime4 cnr_lease_time; 2715 netloc4 cnr_source_server<>; 2716 }; 2718 union COPY_NOTIFY4res switch (nfsstat4 cnr_status) { 2719 case NFS4_OK: 2720 COPY_NOTIFY4resok resok4; 2721 default: 2722 void; 2723 }; 2725 13.3.3. DESCRIPTION 2727 This operation is used for an inter-server copy. A client sends this 2728 operation in a COMPOUND request to the source server to authorize a 2729 destination server identified by cna_destination_server to read the 2730 file specified by CURRENT_FH on behalf of the given user. 2732 The cna_destination_server MUST be specified using the netloc4 2733 network location format. The server is not required to resolve the 2734 cna_destination_server address before completing this operation. 2736 If this operation succeeds, the source server will allow the 2737 cna_destination_server to copy the specified file on behalf of the 2738 given user. If COPY_NOTIFY succeeds, the destination server is 2739 granted permission to read the file as long as both of the following 2740 conditions are met: 2742 o The destination server begins reading the source file before the 2743 cnr_lease_time expires. If the cnr_lease_time expires while the 2744 destination server is still reading the source file, the 2745 destination server is allowed to finish reading the file. 2747 o The client has not issued a COPY_REVOKE for the same combination 2748 of user, filehandle, and destination server. 2750 The cnr_lease_time is chosen by the source server. A cnr_lease_time 2751 of 0 (zero) indicates an infinite lease. To renew the copy lease 2752 time the client should resend the same copy notification request to 2753 the source server. 2755 To avoid the need for synchronized clocks, copy lease times are 2756 granted by the server as a time delta. However, there is a 2757 requirement that the client and server clocks do not drift 2758 excessively over the duration of the lease. There is also the issue 2759 of propagation delay across the network which could easily be several 2760 hundred milliseconds as well as the possibility that requests will be 2761 lost and need to be retransmitted. 2763 To take propagation delay into account, the client should subtract it 2764 from copy lease times (e.g., if the client estimates the one-way 2765 propagation delay as 200 milliseconds, then it can assume that the 2766 lease is already 200 milliseconds old when it gets it). In addition, 2767 it will take another 200 milliseconds to get a response back to the 2768 server. So the client must send a lease renewal or send the copy 2769 offload request to the cna_destination_server at least 400 2770 milliseconds before the copy lease would expire. If the propagation 2771 delay varies over the life of the lease (e.g., the client is on a 2772 mobile host), the client will need to continuously subtract the 2773 increase in propagation delay from the copy lease times. 2775 The server's copy lease period configuration should take into account 2776 the network distance of the clients that will be accessing the 2777 server's resources. It is expected that the lease period will take 2778 into account the network propagation delays and other network delay 2779 factors for the client population. Since the protocol does not allow 2780 for an automatic method to determine an appropriate copy lease 2781 period, the server's administrator may have to tune the copy lease 2782 period. 2784 A successful response will also contain a list of names, addresses, 2785 and URLs called cnr_source_server, on which the source is willing to 2786 accept connections from the destination. These might not be 2787 reachable from the client and might be located on networks to which 2788 the client has no connection. 2790 If the client wishes to perform an inter-server copy, the client MUST 2791 send a COPY_NOTIFY to the source server. Therefore, the source 2792 server MUST support COPY_NOTIFY. 2794 For a copy only involving one server (the source and destination are 2795 on the same server), this operation is unnecessary. 2797 The COPY_NOTIFY operation may fail for the following reasons (this is 2798 a partial list): 2800 o NFS4ERR_MOVED 2802 o NFS4ERR_NOTSUPP 2804 o NFS4ERR_WRONGSEC 2806 13.4. Operation 62: COPY_REVOKE - Revoke a destination server's copy 2807 privileges 2809 13.4.1. ARGUMENT 2811 struct COPY_REVOKE4args { 2812 /* CURRENT_FH: source file */ 2813 netloc4 cra_destination_server; 2814 }; 2816 13.4.2. RESULT 2818 struct COPY_REVOKE4res { 2819 nfsstat4 crr_status; 2820 }; 2822 13.4.3. DESCRIPTION 2824 This operation is used for an inter-server copy. A client sends this 2825 operation in a COMPOUND request to the source server to revoke the 2826 authorization of a destination server identified by 2827 cra_destination_server from reading the file specified by CURRENT_FH 2828 on behalf of given user. If the cra_destination_server has already 2829 begun copying the file, a successful return from this operation 2830 indicates that further access will be prevented. 2832 The cra_destination_server MUST be specified using the netloc4 2833 network location format. The server is not required to resolve the 2834 cra_destination_server address before completing this operation. 2836 The COPY_REVOKE operation is useful in situations in which the source 2837 server granted a very long or infinite lease on the destination 2838 server's ability to read the source file and all copy operations on 2839 the source file have been completed. 2841 For a copy only involving one server (the source and destination are 2842 on the same server), this operation is unnecessary. 2844 If the server supports COPY_NOTIFY, the server is REQUIRED to support 2845 the COPY_REVOKE operation. 2847 The COPY_REVOKE operation may fail for the following reasons (this is 2848 a partial list): 2850 o NFS4ERR_MOVED 2852 o NFS4ERR_NOTSUPP 2854 13.5. Operation 63: COPY_STATUS - Poll for status of a server-side copy 2856 13.5.1. ARGUMENT 2858 struct COPY_STATUS4args { 2859 /* CURRENT_FH: destination file */ 2860 stateid4 csa_stateid; 2861 }; 2863 13.5.2. RESULT 2865 struct COPY_STATUS4resok { 2866 length4 csr_bytes_copied; 2867 nfsstat4 csr_complete<1>; 2868 }; 2870 union COPY_STATUS4res switch (nfsstat4 csr_status) { 2871 case NFS4_OK: 2872 COPY_STATUS4resok resok4; 2873 default: 2874 void; 2875 }; 2877 13.5.3. DESCRIPTION 2879 COPY_STATUS is used for both intra- and inter-server asynchronous 2880 copies. The COPY_STATUS operation allows the client to poll the 2881 server to determine the status of an asynchronous copy operation. 2882 This operation is sent by the client to the destination server. 2884 If this operation is successful, the number of bytes copied are 2885 returned to the client in the csr_bytes_copied field. The 2886 csr_bytes_copied value indicates the number of bytes copied but not 2887 which specific bytes have been copied. 2889 If the optional csr_complete field is present, the copy has 2890 completed. In this case the status value indicates the result of the 2891 asynchronous copy operation. In all cases, the server will also 2892 deliver the final results of the asynchronous copy in a CB_COPY 2893 operation. 2895 The failure of this operation does not indicate the result of the 2896 asynchronous copy in any way. 2898 If the server supports asynchronous copies, the server is REQUIRED to 2899 support the COPY_STATUS operation. 2901 The COPY_STATUS operation may fail for the following reasons (this is 2902 a partial list): 2904 o NFS4ERR_NOTSUPP 2906 o NFS4ERR_BAD_STATEID 2908 o NFS4ERR_EXPIRED 2910 13.6. Modification to Operation 42: EXCHANGE_ID - Instantiate Client ID 2912 13.6.1. ARGUMENT 2914 /* new */ 2915 const EXCHGID4_FLAG_SUPP_FENCE_OPS = 0x00000004; 2917 13.6.2. RESULT 2919 Unchanged 2921 13.6.3. MOTIVATION 2923 Enterprise applications require guarantees that an operation has 2924 either aborted or completed. NFSv4.1 provides this guarantee as long 2925 as the session is alive: simply send a SEQUENCE operation on the same 2926 slot with a new sequence number, and the successful return of 2927 SEQUENCE indicates the previous operation has completed. However, if 2928 the session is lost, there is no way to know when any in progress 2929 operations have aborted or completed. In hindsight, the NFSv4.1 2930 specification should have mandated that DESTROY_SESSION abort/ 2931 complete all outstanding operations. 2933 13.6.4. DESCRIPTION 2935 A client SHOULD request the EXCHGID4_FLAG_SUPP_FENCE_OPS capability 2936 when it sends an EXCHANGE_ID operation. The server SHOULD set this 2937 capability in the EXCHANGE_ID reply whether the client requests it or 2938 not. If the client ID is created with this capability then the 2939 following will occur: 2941 o The server will not reply to DESTROY_SESSION until all operations 2942 in progress are completed or aborted. 2944 o The server will not reply to subsequent EXCHANGE_ID invoked on the 2945 same Client Owner with a new verifier until all operations in 2946 progress on the Client ID's session are completed or aborted. 2948 o When DESTROY_CLIENTID is invoked, if there are sessions (both idle 2949 and non-idle), opens, locks, delegations, layouts, and/or wants 2950 (Section 18.49) associated with the client ID are removed. 2951 Pending operations will be completed or aborted before the 2952 sessions, opens, locks, delegations, layouts, and/or wants are 2953 deleted. 2955 o The NFS server SHOULD support client ID trunking, and if it does 2956 and the EXCHGID4_FLAG_SUPP_FENCE_OPS capability is enabled, then a 2957 session ID created on one node of the storage cluster MUST be 2958 destroyable via DESTROY_SESSION. In addition, DESTROY_CLIENTID 2959 and an EXCHANGE_ID with a new verifier affects all sessions 2960 regardless what node the sessions were created on. 2962 13.7. Operation 64: INITIALIZE 2964 This operation can be used to initialize the structure imposed by an 2965 application onto a file, i.e., ADBs, and to punch a hole into a file. 2967 13.7.1. ARGUMENT 2969 /* 2970 * We use data_content4 in case we wish to 2971 * extend new types later. Note that we 2972 * are explicitly disallowing data. 2973 */ 2974 union initialize_arg4 switch (data_content4 content) { 2975 case NFS4_CONTENT_APP_BLOCK: 2976 app_data_block4 ia_adb; 2977 case NFS4_CONTENT_HOLE: 2978 data_info4 ia_hole; 2979 default: 2980 void; 2981 }; 2983 struct INITIALIZE4args { 2984 /* CURRENT_FH: file */ 2985 stateid4 ia_stateid; 2986 stable_how4 ia_stable; 2987 initialize_arg4 ia_data<>; 2988 }; 2990 13.7.2. RESULT 2992 struct INITIALIZE4resok { 2993 count4 ir_count; 2994 stable_how4 ir_committed; 2995 verifier4 ir_writeverf; 2996 data_content4 ir_sparse; 2997 }; 2999 union INITIALIZE4res switch (nfsstat4 status) { 3000 case NFS4_OK: 3001 INITIALIZE4resok resok4; 3002 default: 3003 void; 3004 }; 3006 13.7.3. DESCRIPTION 3007 13.7.3.1. Hole punching 3009 Whenever a client wishes to zero the blocks backing a particular 3010 region in the file, it calls the INITIALIZE operation with the 3011 current filehandle set to the filehandle of the file in question, and 3012 the equivalent of start offset and length in bytes of the region set 3013 in ia_hole.di_offset and ia_hole.di_length respectively. If the 3014 ia_hole.di_allocated is set to TRUE, then the blocks will be zeroed 3015 and if it is set to FALSE, then they will be deallocated. All 3016 further reads to this region MUST return zeros until overwritten. 3017 The filehandle specified must be that of a regular file. 3019 Situations may arise where di_offset and/or di_offset + di_length 3020 will not be aligned to a boundary that the server does allocations/ 3021 deallocations in. For most filesystems, this is the block size of 3022 the file system. In such a case, the server can deallocate as many 3023 bytes as it can in the region. The blocks that cannot be deallocated 3024 MUST be zeroed. Except for the block deallocation and maximum hole 3025 punching capability, a INITIALIZE operation is to be treated similar 3026 to a write of zeroes. 3028 The server is not required to complete deallocating the blocks 3029 specified in the operation before returning. It is acceptable to 3030 have the deallocation be deferred. In fact, INITIALIZE is merely a 3031 hint; it is valid for a server to return success without ever doing 3032 anything towards deallocating the blocks backing the region 3033 specified. However, any future reads to the region MUST return 3034 zeroes. 3036 If used to hole punch, INITIALIZE will result in the space_used 3037 attribute being decreased by the number of bytes that were 3038 deallocated. The space_freed attribute may or may not decrease, 3039 depending on the support and whether the blocks backing the specified 3040 range were shared or not. The size attribute will remain unchanged. 3042 The INITIALIZE operation MUST NOT change the space reservation 3043 guarantee of the file. While the server can deallocate the blocks 3044 specified by di_offset and di_length, future writes to this region 3045 MUST NOT fail with NFSERR_NOSPC. 3047 The INITIALIZE operation may fail for the following reasons (this is 3048 a partial list): 3050 NFS4ERR_NOTSUPP The Hole punch operations are not supported by the 3051 NFS server receiving this request. 3053 NFS4ERR_DIR The current filehandle is of type NF4DIR. 3055 NFS4ERR_SYMLINK The current filehandle is of type NF4LNK. 3057 NFS4ERR_WRONG_TYPE The current filehandle does not designate an 3058 ordinary file. 3060 13.7.3.2. ADBs 3062 If the server supports ADBs, then it MUST support the 3063 NFS4_CONTENT_APP_BLOCK arm of the INITIALIZE operation. The server 3064 has no concept of the structure imposed by the application. It is 3065 only when the application writes to a section of the file does order 3066 get imposed. In order to detect corruption even before the 3067 application utilizes the file, the application will want to 3068 initialize a range of ADBs using INITIALIZE. 3070 For ADBs, when the client invokes the INITIALIZE operation, it has 3071 two desired results: 3073 1. The structure described by the app_data_block4 be imposed on the 3074 file. 3076 2. The contents described by the app_data_block4 be sparse. 3078 If the server supports the INITIALIZE operation, it still might not 3079 support sparse files. So if it receives the INITIALIZE operation, 3080 then it MUST populate the contents of the file with the initialized 3081 ADBs. 3083 If the data was already initialized, there are two interesting 3084 scenarios: 3086 1. The data blocks are allocated. 3088 2. Initializing in the middle of an existing ADB. 3090 If the data blocks were already allocated, then the INITIALIZE is a 3091 hole punch operation. If INITIALIZE supports sparse files, then the 3092 data blocks are to be deallocated. If not, then the data blocks are 3093 to be rewritten in the indicated ADB format. 3095 Since the server has no knowledge of ADBs, it should not report 3096 misaligned creation of ADBs. Even while it can detect them, it 3097 cannot disallow them, as the application might be in the process of 3098 changing the size of the ADBs. Thus the server must be prepared to 3099 handle an INITIALIZE into an existing ADB. 3101 This document does not mandate the manner in which the server stores 3102 ADBs sparsely for a file. It does assume that if ADBs are stored 3103 sparsely, then the server can detect when an INITIALIZE arrives that 3104 will force a new ADB to start inside an existing ADB. For example, 3105 assume that ADBi has a adb_block_size of 4k and that an INITIALIZE 3106 starts 1k inside ADBi. The server should [[Comment.5: Need to flesh 3107 this out. --TH]] 3109 13.8. Operation 67: IO_ADVISE - Application I/O access pattern hints 3111 This section introduces a new operation, named IO_ADVISE, which 3112 allows NFS clients to communicate application I/O access pattern 3113 hints to the NFS server. This new operation will allow hints to be 3114 sent to the server when applications use posix_fadvise, direct I/O, 3115 or at any other point at which the client finds useful. 3117 13.8.1. ARGUMENT 3119 enum IO_ADVISE_type4 { 3120 IO_ADVISE4_NORMAL = 0, 3121 IO_ADVISE4_SEQUENTIAL = 1, 3122 IO_ADVISE4_SEQUENTIAL_BACKWARDS = 2, 3123 IO_ADVISE4_RANDOM = 3, 3124 IO_ADVISE4_WILLNEED = 4, 3125 IO_ADVISE4_WILLNEED_OPPORTUNISTIC = 5, 3126 IO_ADVISE4_DONTNEED = 6, 3127 IO_ADVISE4_NOREUSE = 7, 3128 IO_ADVISE4_READ = 8, 3129 IO_ADVISE4_WRITE = 9, 3130 IO_ADVISE4_INIT_PROXIMITY = 10 3131 }; 3133 struct IO_ADVISE4args { 3134 /* CURRENT_FH: file */ 3135 stateid4 iar_stateid; 3136 offset4 iar_offset; 3137 length4 iar_count; 3138 bitmap4 iar_hints; 3139 }; 3141 13.8.2. RESULT 3143 struct IO_ADVISE4resok { 3144 bitmap4 ior_hints; 3145 }; 3147 union IO_ADVISE4res switch (nfsstat4 _status) { 3148 case NFS4_OK: 3149 IO_ADVISE4resok resok4; 3150 default: 3151 void; 3152 }; 3154 13.8.3. DESCRIPTION 3156 The IO_ADVISE operation sends an I/O access pattern hint to the 3157 server for the owner of stated for a given byte range specified by 3158 iar_offset and iar_count. The byte range specified by iar_offset and 3159 iar_count need not currently exist in the file, but the iar_hints 3160 will apply to the byte range when it does exist. If iar_count is 0, 3161 all data following iar_offset is specified. The server MAY ignore 3162 the advice. 3164 The following are the possible hints: 3166 IO_ADVISE4_NORMAL Specifies that the application has no advice to 3167 give on its behavior with respect to the specified data. It is 3168 the default characteristic if no advice is given. 3170 IO_ADVISE4_SEQUENTIAL Specifies that the stated holder expects to 3171 access the specified data sequentially from lower offsets to 3172 higher offsets. 3174 IO_ADVISE4_SEQUENTIAL BACKWARDS Specifies that the stated holder 3175 expects to access the specified data sequentially from higher 3176 offsets to lower offsets. 3178 IO_ADVISE4_RANDOM Specifies that the stated holder expects to access 3179 the specified data in a random order. 3181 IO_ADVISE4_WILLNEED Specifies that the stated holder expects to 3182 access the specified data in the near future. 3184 IO_ADVISE4_WILLNEED_OPPORTUNISTIC Specifies that the stated holder 3185 expects to possibly access the data in the near future. This is a 3186 speculative hint, and therefore the server should prefetch data or 3187 indirect blocks only if it can be done at a marginal cost. 3189 IO_ADVISE_DONTNEED Specifies that the stated holder expects that it 3190 will not access the specified data in the near future. 3192 IO_ADVISE_NOREUSE Specifies that the stated holder expects to access 3193 the specified data once and then not reuse it thereafter. 3195 IO_ADVISE4_READ Specifies that the stated holder expects to read the 3196 specified data in the near future. 3198 IO_ADVISE4_WRITE Specifies that the stated holder expects to write 3199 the specified data in the near future. 3201 IO_ADVISE4_INIT_PROXIMITY The client has recently accessed the byte 3202 range in its own cache. This informs the server that the data in 3203 the byte range remains important to the client. When the server 3204 reaches resource exhaustion, knowing which data is more important 3205 allows the server to make better choices about which data to, for 3206 example purge from a cache, or move to secondary storage. It also 3207 informs the server which delegations are more important, since if 3208 delegations are working correctly, once delegated to a client, a 3209 server might never receive another I/O request for the file. 3211 The server will return success if the operation is properly formed, 3212 otherwise the server will return an error. The server MUST NOT 3213 return an error if it does not recognize or does not support the 3214 requested advice. This is also true even if the client sends 3215 contradictory hints to the server, e.g., IO_ADVISE4_SEQUENTIAL and 3216 IO_ADVISE4_RANDOM in a single IO_ADVISE operation. In this case, the 3217 server MUST return success and a ior_hints value that indicates the 3218 hint it intends to optimize. For contradictory hints, this may mean 3219 simply returning IO_ADVISE4_NORMAL for example. 3221 The ior_hints returned by the server is primarily for debugging 3222 purposes since the server is under no obligation to carry out the 3223 hints that it describes in the ior_hints result. In addition, while 3224 the server may have intended to implement the hints returned in 3225 ior_hints, as time progresses, the server may need to change its 3226 handling of a given file due to several reasons including, but not 3227 limited to, memory pressure, additional IO_ADVISE hints sent by other 3228 clients, and heuristically detected file access patterns. 3230 The server MAY return different advice than what the client 3231 requested. If it does, then this might be due to one of several 3232 conditions, including, but not limited to another client advising of 3233 a different I/O access pattern; a different I/O access pattern from 3234 another client that that the server has heuristically detected; or 3235 the server is not able to support the requested I/O access pattern, 3236 perhaps due to a temporary resource limitation. 3238 Each issuance of the IO_ADVISE operation overrides all previous 3239 issuances of IO_ADVISE for a given byte range. This effectively 3240 follows a strategy of last hint wins for a given stated and byte 3241 range. 3243 Clients should assume that hints included in an IO_ADVISE operation 3244 will be forgotten once the file is closed. 3246 13.8.4. IMPLEMENTATION 3248 The NFS client may choose to issue an IO_ADVISE operation to the 3249 server in several different instances. 3251 The most obvious is in direct response to an applications execution 3252 of posix_fadvise. In this case, IO_ADVISE4_WRITE and IO_ADVISE4_READ 3253 may be set based upon the type of file access specified when the file 3254 was opened. 3256 Another useful point would be when an application indicates it is 3257 using direct I/O. Direct I/O may be specified at file open, in which 3258 case a IO_ADVISE may be included in the same compound as the OPEN 3259 operation with the IO_ADVISE4_NOREUSE flag set. Direct I/O may also 3260 be specified separately, in which case a IO_ADVISE operation can be 3261 sent to the server separately. As above, IO_ADVISE4_WRITE and 3262 IO_ADVISE4_READ may be set based upon the type of file access 3263 specified when the file was opened. 3265 13.8.5. pNFS File Layout Data Type Considerations 3267 The IO_ADVISE considerations for pNFS are very similar to the COMMIT 3268 considerations for pNFS. That is, as with COMMIT, some NFS server 3269 implementations prefer IO_ADVISE be done on the DS, and some prefer 3270 it be done on the MDS. 3272 So for the file's layout type, it is proposed that NFSv4.2 include an 3273 additional hint NFL42_CARE_IO_ADVISE_THRU_MDS which is valid only on 3274 NFSv4.2 or higher. Any file's layout obtained with NFSv4.1 MUST NOT 3275 have NFL42_UFLG_IO_ADVISE_THRU_MDS set. Any file's layout obtained 3276 with NFSv4.2 MAY have NFL42_UFLG_IO_ADVISE_THRU_MDS set. If the 3277 client does not implement IO_ADVISE, then it MUST ignore 3278 NFL42_UFLG_IO_ADVISE_THRU_MDS. 3280 If NFL42_UFLG_IO_ADVISE_THRU_MDS is set, then if the client 3281 implements IO_ADVISE, then if it wants the DS to honor IO_ADVISE, the 3282 client MUST send the operation to the MDS, and the server will 3283 communicate the advice back each DS. If the client sends IO_ADVISE 3284 to the DS, then the server MAY return NFS4ERR_NOTSUPP. 3286 If NFL42_UFLG_IO_ADVISE_THRU_MDS is not set, then this indicates to 3287 client that if wants to inform the server via IO_ADVISE of the 3288 client's intended use of the file, then the client SHOULD send an 3289 IO_ADVISE to each DS. While the client MAY always send IO_ADVISE to 3290 the MDS, if the server has not set NFL42_UFLG_IO_ADVISE_THRU_MDS, the 3291 client should expect that such an IO_ADVISE is futile. Note that a 3292 client SHOULD use the same set of arguments on each IO_ADVISE sent to 3293 a DS for the same open file reference. 3295 The server is not required to support different advice for different 3296 DS's with the same open file reference. 3298 13.8.5.1. Dense and Sparse Packing Considerations 3300 The IO_ADVISE operation MUST use the iar_offset and byte range as 3301 dictated by the presence or absence of NFL4_UFLG_DENSE. 3303 E.g., if NFL4_UFLG_DENSE is present, and a READ or WRITE to the DS 3304 for iar_offset 0 really means iar_offset 10000 in the logical file, 3305 then an IO_ADVISE for iar_offset 0 means iar_offset 10000. 3307 E.g., if NFL4_UFLG_DENSE is absent, then a READ or WRITE to the DS 3308 for iar_offset 0 really means iar_offset 0 in the logical file, then 3309 an IO_ADVISE for iar_offset 0 means iar_offset 0 in the logical file. 3311 E.g., if NFL4_UFLG_DENSE is present, the stripe unit is 1000 bytes 3312 and the stripe count is 10, and the dense DS file is serving 3313 iar_offset 0. A READ or WRITE to the DS for iar_offsets 0, 1000, 3314 2000, and 3000, really mean iar_offsets 10000, 20000, 30000, and 3315 40000 (implying a stripe count of 10 and a stripe unit of 1000), then 3316 an IO_ADVISE sent to the same DS with an iar_offset of 500, and a 3317 iar_count of 3000 means that the IO_ADVISE applies to these byte 3318 ranges of the dense DS file: 3320 - 500 to 999 3321 - 1000 to 1999 3322 - 2000 to 2999 3323 - 3000 to 3499 3325 I.e., the contiguous range 500 to 3499 as specified in IO_ADVISE. 3327 It also applies to these byte ranges of the logical file: 3329 - 10500 to 10999 (500 bytes) 3330 - 20000 to 20999 (1000 bytes) 3331 - 30000 to 30999 (1000 bytes) 3332 - 40000 to 40499 (500 bytes) 3333 (total 3000 bytes) 3335 E.g., if NFL4_UFLG_DENSE is absent, the stripe unit is 250 bytes, the 3336 stripe count is 4, and the sparse DS file is serving iar_offset 0. 3337 Then a READ or WRITE to the DS for iar_offsets 0, 1000, 2000, and 3338 3000, really mean iar_offsets 0, 1000, 2000, and 3000 in the logical 3339 file, keeping in mind that on the DS file,. byte ranges 250 to 999, 3340 1250 to 1999, 2250 to 2999, and 3250 to 3999 are not accessible. 3341 Then an IO_ADVISE sent to the same DS with an iar_offset of 500, and 3342 a iar_count of 3000 means that the IO_ADVISE applies to these byte 3343 ranges of the logical file and the sparse DS file: 3345 - 500 to 999 (500 bytes) - no effect 3346 - 1000 to 1249 (250 bytes) - effective 3347 - 1250 to 1999 (750 bytes) - no effect 3348 - 2000 to 2249 (250 bytes) - effective 3349 - 2250 to 2999 (750 bytes) - no effect 3350 - 3000 to 3249 (250 bytes) - effective 3351 - 3250 to 3499 (250 bytes) - no effect 3352 (subtotal 2250 bytes) - no effect 3353 (subtotal 750 bytes) - effective 3354 (grand total 3000 bytes) - no effect + effective 3356 If neither of the flags NFL42_UFLG_IO_ADVISE_THRU_MDS and 3357 NFL4_UFLG_DENSE are set in the layout, then any IO_ADVISE request 3358 sent to the data server with a byte range that overlaps stripe unit 3359 that the data server does not serve MUST NOT result in the status 3360 NFS4ERR_PNFS_IO_HOLE. Instead, the response SHOULD be successful and 3361 if the server applies IO_ADVISE hints on any stripe units that 3362 overlap with the specified range, those hints SHOULD be indicated in 3363 the response. 3365 13.8.6. Number of Supported File Segments 3367 In theory IO_ADVISE allows a client and server to support multiple 3368 file segments, meaning that different, possibly overlapping, byte 3369 ranges of the same open file reference will support different hints. 3370 This is not practical, and in general the server will support just 3371 one set of hints, and these will apply to the entire file. However, 3372 there are some hints that very ephemeral, and are essentially amount 3373 to one time instructions to the NFS server, which will be forgotten 3374 momentarily after IO_ADVISE is executed. 3376 The following hints will always apply to the entire file, regardless 3377 of the specified byte range: 3379 o IO_ADVISE4_NORMAL 3381 o IO_ADVISE4_SEQUENTIAL 3383 o IO_ADVISE4_SEQUENTIAL_BACKWARDS 3385 o IO_ADVISE4_RANDOM 3387 The following hints will always apply to specified byte range, and 3388 will treated as one time instructions: 3390 o IO_ADVISE4_WILLNEED 3392 o IO_ADVISE4_WILLNEED_OPPORTUNISTIC 3394 o IO_ADVISE4_DONTNEED 3396 o IO_ADVISE4_NOREUSE 3398 The following hints are modifiers to all other hints, and will apply 3399 to the entire file and/or to a one time instruction on the specified 3400 byte range: 3402 o IO_ADVISE4_READ 3404 o IO_ADVISE4_WRITE 3406 13.9. Changes to Operation 51: LAYOUTRETURN 3408 13.9.1. Introduction 3410 In the pNFS description provided in [2], the client is not enabled to 3411 relay an error code from the DS to the MDS. In the specification of 3412 the Objects-Based Layout protocol [9], use is made of the opaque 3413 lrf_body field of the LAYOUTRETURN argument to do such a relaying of 3414 error codes. In this section, we define a new data structure to 3415 enable the passing of error codes back to the MDS and provide some 3416 guidelines on what both the client and MDS should expect in such 3417 circumstances. 3419 There are two broad classes of errors, transient and persistent. The 3420 client SHOULD strive to only use this new mechanism to report 3421 persistent errors. It MUST be able to deal with transient issues by 3422 itself. Also, while the client might consider an issue to be 3423 persistent, it MUST be prepared for the MDS to consider such issues 3424 to be persistent. A prime example of this is if the MDS fences off a 3425 client from either a stateid or a filehandle. The client will get an 3426 error from the DS and might relay either NFS4ERR_ACCESS or 3427 NFS4ERR_STALE_STATEID back to the MDS, with the belief that this is a 3428 hard error. The MDS on the other hand, is waiting for the client to 3429 report such an error. For it, the mission is accomplished in that 3430 the client has returned a layout that the MDS had most likley 3431 recalled. 3433 The existing LAYOUTRETURN operation is extended by introducing a new 3434 data structure to report errors, layoutreturn_device_error4. Also, 3435 layoutreturn_device_error4 is introduced to enable an array of errors 3436 to be reported. 3438 13.9.2. ARGUMENT 3440 The ARGUMENT specification of the LAYOUTRETURN operation in section 3441 18.44.1 of [2] is augmented by the following XDR code [23]: 3443 struct layoutreturn_device_error4 { 3444 deviceid4 lrde_deviceid; 3445 nfsstat4 lrde_status; 3446 nfs_opnum4 lrde_opnum; 3447 }; 3449 struct layoutreturn_error_report4 { 3450 layoutreturn_device_error4 lrer_errors<>; 3451 }; 3453 13.9.3. RESULT 3455 The RESULT of the LAYOUTRETURN operation is unchanged; see section 3456 18.44.2 of [2]. 3458 13.9.4. DESCRIPTION 3460 The following text is added to the end of the LAYOUTRETURN operation 3461 DESCRIPTION in section 18.44.3 of [2]. 3463 When a client used LAYOUTRETURN with a type of LAYOUTRETURN4_FILE, 3464 then if the lrf_body field is NULL, it indicates to the MDS that the 3465 client experienced no errors. If lrf_body is non-NULL, then the 3466 field references error information which is layout type specific. 3467 I.e., the Objects-Based Layout protocol can continue to utilize 3468 lrf_body as specified in [9]. For both Files-Based Layouts, the 3469 field references a layoutreturn_device_error4, which contains an 3470 array of layoutreturn_device_error4. 3472 Each individual layoutreturn_device_error4 descibes a single error 3473 associated with a DS, which is identfied via lrde_deviceid. The 3474 operation which returned the error is identified via lrde_opnum. 3475 Finally the NFS error value (nfsstat4) encountered is provided via 3476 lrde_status and may consist of the following error codes: 3478 NFS4_OKAY: No issues were found for this device. 3480 NFS4ERR_NXIO: The client was unable to establish any communication 3481 with the DS. 3483 NFS4ERR_*: The client was able to establish communication with the 3484 DS and is returning one of the allowed error codes for the 3485 operation denoted by lrde_opnum. 3487 13.9.5. IMPLEMENTATION 3489 The following text is added to the end of the LAYOUTRETURN operation 3490 IMPLEMENTATION in section 18.4.4 of [2]. 3492 A client that expects to use pNFS for a mounted filesystem SHOULD 3493 check for pNFS support at mount time. This check SHOULD be performed 3494 by sending a GETDEVICELIST operation, followed by layout-type- 3495 specific checks for accessibility of each storage device returned by 3496 GETDEVICELIST. If the NFS server does not support pNFS, the 3497 GETDEVICELIST operation will be rejected with an NFS4ERR_NOTSUPP 3498 error; in this situation it is up to the client to determine whether 3499 it is acceptable to proceed with NFS-only access. 3501 Clients are expected to tolerate transient storage device errors, and 3502 hence clients SHOULD NOT use the LAYOUTRETURN error handling for 3503 device access problems that may be transient. The methods by which a 3504 client decides whether an access problem is transient vs. persistent 3505 are implementation-specific, but may include retrying I/Os to a data 3506 server under appropriate conditions. 3508 When an I/O fails to a storage device, the client SHOULD retry the 3509 failed I/O via the MDS. In this situation, before retrying the I/O, 3510 the client SHOULD return the layout, or the affected portion thereof, 3511 and SHOULD indicate which storage device or devices was problematic. 3512 If the client does not do this, the MDS may issue a layout recall 3513 callback in order to perform the retried I/O. 3515 The client needs to be cognizant that since this error handling is 3516 optional in the MDS, the MDS may silently ignore this functionality. 3517 Also, as the MDS may consider some issues the client reports to be 3518 expected (see Section 13.9.1), the client might find it difficult to 3519 detect a MDS which has not implemented error handling via 3520 LAYOUTRETURN. 3522 If an MDS is aware that a storage device is proving problematic to a 3523 client, the MDS SHOULD NOT include that storage device in any pNFS 3524 layouts sent to that client. If the MDS is aware that a storage 3525 device is affecting many clients, then the MDS SHOULD NOT include 3526 that storage device in any pNFS layouts sent out. Clients must still 3527 be aware that the MDS might not have any choice in using the storage 3528 device, i.e., there might only be one possible layout for the system. 3530 Another interesting complication is that for existing files, the MDS 3531 might have no choice in which storage devices to hand out to clients. 3532 The MDS might try to restripe a file across a different storage 3533 device, but clients need to be aware that not all implementations 3534 have restriping support. 3536 An MDS SHOULD react to a client return of layouts with errors by not 3537 using the problematic storage devices in layouts for that client, but 3538 the MDS is not required to indefinitely retain per-client storage 3539 device error information. An MDS is also not required to 3540 automatically reinstate use of a previously problematic storage 3541 device; administrative intervention may be required instead. 3543 A client MAY perform I/O via the MDS even when the client holds a 3544 layout that covers the I/O; servers MUST support this client 3545 behavior, and MAY recall layouts as needed to complete I/Os. 3547 13.10. Operation 65: READ_PLUS 3549 READ_PLUS is a new read operation which allows NFS clients to avoid 3550 reading holes in a sparse file and to efficiently transfer ADBs. 3551 READ_PLUS supports all the features of the existing NFSv4.1 READ 3552 operation [2] but also extends the response to avoid returning data 3553 for portions of the file which are either initialized and contain no 3554 backing store or if the result would appear to be so. I.e., if the 3555 result was a data block composed entirely of zeros, then it is easier 3556 to return a hole. Returning data blocks of unitialized data wastes 3557 computational and network resources, thus reducing performance. 3558 READ_PLUS uses a new result structure that tells the client that the 3559 result is all zeroes AND the byte-range of the hole in which the 3560 request was made. 3562 If the client sends a READ operation, it is explicitly stating that 3563 it is neither supporting sparse files nor ADBs. So if a READ occurs 3564 on a sparse ADB or file, then the server must expand such data to be 3565 raw bytes. If a READ occurs in the middle of a hole or ADB, the 3566 server can only send back bytes starting from that offset. 3568 Such an operation is inefficient for transfer of sparse sections of 3569 the file. As such, READ is marked as OBSOLETE in NFSv4.2. Instead, 3570 a client should issue READ_PLUS. Note that as the client has no a 3571 priori knowledge of whether either an ADB or a hole is present or 3572 not, it should always use READ_PLUS. 3574 13.10.1. ARGUMENT 3576 struct READ_PLUS4args { 3577 /* CURRENT_FH: file */ 3578 stateid4 rpa_stateid; 3579 offset4 rpa_offset; 3580 count4 rpa_count; 3581 }; 3583 13.10.2. RESULT 3585 union read_plus_content switch (data_content4 content) { 3586 case NFS4_CONTENT_DATA: 3587 opaque rpc_data<>; 3588 case NFS4_CONTENT_APP_BLOCK: 3589 app_data_block4 rpc_block; 3590 case NFS4_CONTENT_HOLE: 3591 data_info4 rpc_hole; 3592 default: 3593 void; 3594 }; 3596 /* 3597 * Allow a return of an array of contents. 3598 */ 3599 struct read_plus_res4 { 3600 bool rpr_eof; 3601 read_plus_content rpr_contents<>; 3602 }; 3604 union READ_PLUS4res switch (nfsstat4 status) { 3605 case NFS4_OK: 3606 read_plus_res4 resok4; 3607 default: 3608 void; 3609 }; 3611 13.10.3. DESCRIPTION 3613 The READ_PLUS operation is based upon the NFSv4.1 READ operation [2] 3614 and similarly reads data from the regular file identified by the 3615 current filehandle. 3617 The client provides a rpa_offset of where the READ_PLUS is to start 3618 and a rpa_count of how many bytes are to be read. A rpa_offset of 3619 zero means to read data starting at the beginning of the file. If 3620 rpa_offset is greater than or equal to the size of the file, the 3621 status NFS4_OK is returned with di_length (the data length) set to 3622 zero and eof set to TRUE. READ_PLUS is subject to access permissions 3623 checking. 3625 The READ_PLUS result is comprised of an array of rpr_contents, each 3626 of which describe a data_content4 type of data. For NFSv4.2, the 3627 allowed values are data, ADB, and hole. A server is required to 3628 support the data type, but neither ADB nor hole. Both an ADB and a 3629 hole must be returned in its entirety - clients must be prepared to 3630 get more information than they requested. 3632 READ_PLUS has to support all of the errors which are returned by READ 3633 plus NFS4ERR_UNION_NOTSUPP. If the client asks for a hole and the 3634 server does not support that arm of the discriminated union, but does 3635 support one or more additional arms, it can signal to the client that 3636 it supports the operation, but not the arm with 3637 NFS4ERR_UNION_NOTSUPP. 3639 If the data to be returned is comprised entirely of zeros, then the 3640 server may elect to return that data as a hole. The server 3641 differentiates this to the client by setting di_allocated to TRUE in 3642 this case. Note that in such a scenario, the server is not required 3643 to determine the full extent of the "hole" - it does not need to 3644 determine where the zeros start and end. 3646 The server may elect to return adjacent elements of the same type. 3647 For example, the guard pattern or block size of an ADB might change, 3648 which would require adjacent elements of type ADB. Likewise if the 3649 server has a range of data comprised entirely of zeros and then a 3650 hole, it might want to return two adjacent holes to the client. 3652 If the client specifies a rpa_count value of zero, the READ_PLUS 3653 succeeds and returns zero bytes of data, again subject to access 3654 permissions checking. In all situations, the server may choose to 3655 return fewer bytes than specified by the client. The client needs to 3656 check for this condition and handle the condition appropriately. 3658 If the client specifies an rpa_offset and rpa_count value that is 3659 entirely contained within a hole of the file, then the di_offset and 3660 di_length returned must be for the entire hole. This result is 3661 considered valid until the file is changed (detected via the change 3662 attribute). The server MUST provide the same semantics for the hole 3663 as if the client read the region and received zeroes; the implied 3664 holes contents lifetime MUST be exactly the same as any other read 3665 data. 3667 If the client specifies an rpa_offset and rpa_count value that begins 3668 in a non-hole of the file but extends into hole the server should 3669 return an array comprised of both data and a hole. The client MUST 3670 be prepared for the server to reurn a short read describing just the 3671 data. The client will then issue another READ_PLUS for the remaining 3672 bytes, which the server will respond with information about the hole 3673 in the file. 3675 Except when special stateids are used, the stateid value for a 3676 READ_PLUS request represents a value returned from a previous byte- 3677 range lock or share reservation request or the stateid associated 3678 with a delegation. The stateid identifies the associated owners if 3679 any and is used by the server to verify that the associated locks are 3680 still valid (e.g., have not been revoked). 3682 If the read ended at the end-of-file (formally, in a correctly formed 3683 READ_PLUS operation, if rpa_offset + rpa_count is equal to the size 3684 of the file), or the READ_PLUS operation extends beyond the size of 3685 the file (if rpa_offset + rpa_count is greater than the size of the 3686 file), eof is returned as TRUE; otherwise, it is FALSE. A successful 3687 READ_PLUS of an empty file will always return eof as TRUE. 3689 If the current filehandle is not an ordinary file, an error will be 3690 returned to the client. In the case that the current filehandle 3691 represents an object of type NF4DIR, NFS4ERR_ISDIR is returned. If 3692 the current filehandle designates a symbolic link, NFS4ERR_SYMLINK is 3693 returned. In all other cases, NFS4ERR_WRONG_TYPE is returned. 3695 For a READ_PLUS with a stateid value of all bits equal to zero, the 3696 server MAY allow the READ_PLUS to be serviced subject to mandatory 3697 byte-range locks or the current share deny modes for the file. For a 3698 READ_PLUS with a stateid value of all bits equal to one, the server 3699 MAY allow READ_PLUS operations to bypass locking checks at the 3700 server. 3702 On success, the current filehandle retains its value. 3704 13.10.4. IMPLEMENTATION 3706 If the server returns a short read, then the client should send 3707 another READ_PLUS to get the remaining data. A server may return 3708 less data than requested under several circumstances. The file may 3709 have been truncated by another client or perhaps on the server 3710 itself, changing the file size from what the requesting client 3711 believes to be the case. This would reduce the actual amount of data 3712 available to the client. It is possible that the server reduced the 3713 transfer size and so return a short read result. Server resource 3714 exhaustion may also occur in a short read. 3716 If mandatory byte-range locking is in effect for the file, and if the 3717 byte-range corresponding to the data to be read from the file is 3718 WRITE_LT locked by an owner not associated with the stateid, the 3719 server will return the NFS4ERR_LOCKED error. The client should try 3720 to get the appropriate READ_LT via the LOCK operation before re- 3721 attempting the READ_PLUS. When the READ_PLUS completes, the client 3722 should release the byte-range lock via LOCKU. In addition, the 3723 server MUST return an array of rpr_contents with values of that are 3724 within the owner's locked byte range. 3726 If another client has an OPEN_DELEGATE_WRITE delegation for the file 3727 being read, the delegation must be recalled, and the operation cannot 3728 proceed until that delegation is returned or revoked. Except where 3729 this happens very quickly, one or more NFS4ERR_DELAY errors will be 3730 returned to requests made while the delegation remains outstanding. 3731 Normally, delegations will not be recalled as a result of a READ_PLUS 3732 operation since the recall will occur as a result of an earlier OPEN. 3733 However, since it is possible for a READ_PLUS to be done with a 3734 special stateid, the server needs to check for this case even though 3735 the client should have done an OPEN previously. 3737 13.10.4.1. Additional pNFS Implementation Information 3739 With pNFS, the semantics of using READ_PLUS remains the same. Any 3740 data server MAY return a hole or ADB result for a READ_PLUS request 3741 that it receives. 3743 When a data server chooses to return a hole result, it has the option 3744 of returning hole information for the data stored on that data server 3745 (as defined by the data layout), but it MUST not return results for a 3746 byte range that includes data managed by another data server. Data 3747 servers that can obtain hole information for the parts of the file 3748 stored on that data server, the data server SHOULD return HOLE_INFO 3749 and the byte range of the hole stored on that data server. 3751 A data server should do its best to return as much information about 3752 a hole as is feasible without having to contact the metadata server. 3753 If communication with the metadata server is required, then every 3754 attempt should be taken to minimize the number of requests. 3756 If mandatory locking is enforced, then the data server must also 3757 ensure that to return only information for a Hole that is within the 3758 owner's locked byte range. 3760 13.10.5. READ_PLUS with Sparse Files Example 3762 The following table describes a sparse file. For each byte range, 3763 the file contains either non-zero data or a hole. In addition, the 3764 server in this example uses a Hole Threshold of 32K. 3766 +-------------+----------+ 3767 | Byte-Range | Contents | 3768 +-------------+----------+ 3769 | 0-15999 | Hole | 3770 | 16K-31999 | Non-Zero | 3771 | 32K-255999 | Hole | 3772 | 256K-287999 | Non-Zero | 3773 | 288K-353999 | Hole | 3774 | 354K-417999 | Non-Zero | 3775 +-------------+----------+ 3777 Table 4 3779 Under the given circumstances, if a client was to read from the file 3780 with a max read size of 64K, the following will be the results for 3781 the given READ_PLUS calls. This assumes the client has already 3782 opened the file, acquired a valid stateid ('s' in the example), and 3783 just needs to issue READ_PLUS requests. 3785 1. READ_PLUS(s, 0, 64K) --> NFS_OK, eof = false, . Since the first hole is less than the server's 3787 Hole Threshhold, the first 32K of the file is returned as data 3788 and the remaining 32K is returned as a hole which actually 3789 extends to 256K. 3791 2. READ_PLUS(s, 32K, 64K) --> NFS_OK, eof = false, 3792 The requested range was all zeros, and the current hole begins at 3793 offset 32K and is 224K in length. Note that the client should 3794 not have followed up the previous READ_PLUS request with this one 3795 as the hole information from the previous call extended past what 3796 the client was requesting. 3798 3. READ_PLUS(s, 256K, 64K) --> NFS_OK, eof = false, . Returns an array of the 32K data and 3800 the hole which extends to 354K. 3802 4. READ_PLUS(s, 354K, 64K) --> NFS_OK, eof = true, . Returns the final 64K of data and informs the client 3804 there is no more data in the file. 3806 13.11. Operation 66: SEEK 3808 SEEK is an operation that allows a client to determine the location 3809 of the next data_content4 in a file. 3811 13.11.1. ARGUMENT 3813 struct SEEK4args { 3814 /* CURRENT_FH: file */ 3815 stateid4 sa_stateid; 3816 offset4 sa_offset; 3817 data_content4 sa_what; 3818 }; 3820 13.11.2. RESULT 3822 union seek_content switch (data_content4 content) { 3823 case NFS4_CONTENT_DATA: 3824 data_info4 sc_data; 3825 case NFS4_CONTENT_APP_BLOCK: 3826 app_data_block4 sc_block; 3827 case NFS4_CONTENT_HOLE: 3828 data_info4 sc_hole; 3829 default: 3830 void; 3831 }; 3833 struct seek_res4 { 3834 bool sr_eof; 3835 seek_content sr_contents; 3836 }; 3838 union SEEK4res switch (nfsstat4 status) { 3839 case NFS4_OK: 3840 seek_res4 resok4; 3841 default: 3842 void; 3843 }; 3845 13.11.3. DESCRIPTION 3847 From the given sa_offset, find the next data_content4 of type sa_what 3848 in the file. For either a hole or ADB, this must return the 3849 data_content4 in its entirety. For data, it must not return the 3850 actual data. 3852 SEEK must follow the same rules for stateids as READ_PLUS 3853 (Section 13.10.3). 3855 If the server could not find a corresponding sa_what, then the status 3856 would still be NFS4_OK, but sr_eof would be TRUE. The sr_contents 3857 would contain a zero-ed out content of the appropriate type. 3859 14. NFSv4.2 Callback Operations 3861 14.1. Procedure 16: CB_ATTR_CHANGED - Notify Client that the File's 3862 Attributes Changed 3864 14.1.1. ARGUMENTS 3866 struct CB_ATTR_CHANGED4args { 3867 nfs_fh4 acca_fh; 3868 bitmap4 acca_critical; 3869 bitmap4 acca_info; 3870 }; 3872 14.1.2. RESULTS 3874 struct CB_ATTR_CHANGED4res { 3875 nfsstat4 accr_status; 3876 }; 3878 14.1.3. DESCRIPTION 3880 The CB_ATTR_CHANGED callback operation is used by the server to 3881 indicate to the client that the file's attributes have been modified 3882 on the server. The server does not convey how the attributes have 3883 changed, just that they have been modified. The server can inform 3884 the client about both critical and informational attribute changes in 3885 the bitmask arguments. The client SHOULD query the server about all 3886 attributes set in acca_critical. For all changes reflected in 3887 acca_info, the client can decide whether or not it wants to poll the 3888 server. 3890 The CB_ATTR_CHANGED callback operation with the FATTR4_SEC_LABEL set 3891 in acca_critical is the method used by the server to indicate that 3892 the MAC label for the file referenced by acca_fh has changed. In 3893 many ways, the server does not care about the result returned by the 3894 client. 3896 14.2. Operation 15: CB_COPY - Report results of a server-side copy 3898 14.2.1. ARGUMENT 3900 union copy_info4 switch (nfsstat4 cca_status) { 3901 case NFS4_OK: 3902 void; 3903 default: 3904 length4 cca_bytes_copied; 3905 }; 3907 struct CB_COPY4args { 3908 nfs_fh4 cca_fh; 3909 stateid4 cca_stateid; 3910 copy_info4 cca_copy_info; 3911 }; 3913 14.2.2. RESULT 3915 struct CB_COPY4res { 3916 nfsstat4 ccr_status; 3917 }; 3919 14.2.3. DESCRIPTION 3921 CB_COPY is used for both intra- and inter-server asynchronous copies. 3922 The CB_COPY callback informs the client of the result of an 3923 asynchronous server-side copy. This operation is sent by the 3924 destination server to the client in a CB_COMPOUND request. The copy 3925 is identified by the filehandle and stateid arguments. The result is 3926 indicated by the status field. If the copy failed, cca_bytes_copied 3927 contains the number of bytes copied before the failure occurred. The 3928 cca_bytes_copied value indicates the number of bytes copied but not 3929 which specific bytes have been copied. 3931 In the absence of an established backchannel, the server cannot 3932 signal the completion of the COPY via a CB_COPY callback. The loss 3933 of a callback channel would be indicated by the server setting the 3934 SEQ4_STATUS_CB_PATH_DOWN flag in the sr_status_flags field of the 3935 SEQUENCE operation. The client must re-establish the callback 3936 channel to receive the status of the COPY operation. Prolonged loss 3937 of the callback channel could result in the server dropping the COPY 3938 operation state and invalidating the copy stateid. 3940 If the client supports the COPY operation, the client is REQUIRED to 3941 support the CB_COPY operation. 3943 The CB_COPY operation may fail for the following reasons (this is a 3944 partial list): 3946 NFS4ERR_NOTSUPP: The copy offload operation is not supported by the 3947 NFS client receiving this request. 3949 15. IANA Considerations 3951 This section uses terms that are defined in [24]. 3953 16. References 3955 16.1. Normative References 3957 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 3958 Levels", March 1997. 3960 [2] Shepler, S., Eisler, M., and D. Noveck, "Network File System 3961 (NFS) Version 4 Minor Version 1 Protocol", RFC 5661, 3962 January 2010. 3964 [3] Haynes, T., "Network File System (NFS) Version 4 Minor Version 3965 2 External Data Representation Standard (XDR) Description", 3966 March 2011. 3968 [4] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 3969 Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, 3970 January 2005. 3972 [5] Haynes, T. and N. Williams, "Remote Procedure Call (RPC) 3973 Security Version 3", draft-williams-rpcsecgssv3 (work in 3974 progress), 2011. 3976 [6] The Open Group, "Section 'posix_fadvise()' of System Interfaces 3977 of The Open Group Base Specifications Issue 6, IEEE Std 1003.1, 3978 2004 Edition", 2004. 3980 [7] Haynes, T., "Requirements for Labeled NFS", 3981 draft-ietf-nfsv4-labreqs-00 (work in progress). 3983 [8] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol 3984 Specification", RFC 2203, September 1997. 3986 [9] Halevy, B., Welch, B., and J. Zelenka, "Object-Based Parallel 3987 NFS (pNFS) Operations", RFC 5664, January 2010. 3989 16.2. Informative References 3991 [10] Haynes, T. and D. Noveck, "Network File System (NFS) version 4 3992 Protocol", draft-ietf-nfsv4-rfc3530bis-09 (Work In Progress), 3993 March 2011. 3995 [11] Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M. Naik, 3996 "NSDB Protocol for Federated Filesystems", 3997 draft-ietf-nfsv4-federated-fs-protocol (Work In Progress), 3998 2010. 4000 [12] Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M. Naik, 4001 "Administration Protocol for Federated Filesystems", 4002 draft-ietf-nfsv4-federated-fs-admin (Work In Progress), 2010. 4004 [13] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., 4005 Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- 4006 HTTP/1.1", RFC 2616, June 1999. 4008 [14] Postel, J. and J. Reynolds, "File Transfer Protocol", STD 9, 4009 RFC 959, October 1985. 4011 [15] Simpson, W., "PPP Challenge Handshake Authentication Protocol 4012 (CHAP)", RFC 1994, August 1996. 4014 [16] VanDeBogart, S., Frost, C., and E. Kohler, "Reducing Seek 4015 Overhead with Application-Directed Prefetching", Proceedings of 4016 USENIX Annual Technical Conference , June 2009. 4018 [17] Strohm, R., "Chapter 2, Data Blocks, Extents, and Segments, of 4019 Oracle Database Concepts 11g Release 1 (11.1)", January 2011. 4021 [18] Ashdown, L., "Chapter 15, Validating Database Files and 4022 Backups, of Oracle Database Backup and Recovery User's Guide 4023 11g Release 1 (11.1)", August 2008. 4025 [19] McDougall, R. and J. Mauro, "Section 11.4.3, Detecting Memory 4026 Corruption of Solaris Internals", 2007. 4028 [20] Bairavasundaram, L., Goodson, G., Schroeder, B., Arpaci- 4029 Dusseau, A., and R. Arpaci-Dusseau, "An Analysis of Data 4030 Corruption in the Storage Stack", Proceedings of the 6th USENIX 4031 Symposium on File and Storage Technologies (FAST '08) , 2008. 4033 [21] "Section 46.6. Multi-Level Security (MLS) of Deployment Guide: 4034 Deployment, configuration and administration of Red Hat 4035 Enterprise Linux 5, Edition 6", 2011. 4037 [22] Quigley, D. and J. Lu, "Registry Specification for MAC Security 4038 Label Formats", draft-quigley-label-format-registry (work in 4039 progress), 2011. 4041 [23] Eisler, M., "XDR: External Data Representation Standard", 4042 RFC 4506, May 2006. 4044 [24] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA 4045 Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. 4047 Appendix A. Acknowledgments 4049 For the pNFS Access Permissions Check, the original draft was by 4050 Sorin Faibish, David Black, Mike Eisler, and Jason Glasgow. The work 4051 was influenced by discussions with Benny Halevy and Bruce Fields. A 4052 review was done by Tom Haynes. 4054 For the Sharing change attribute implementation details with NFSv4 4055 clients, the original draft was by Trond Myklebust. 4057 For the NFS Server-side Copy, the original draft was by James 4058 Lentini, Mike Eisler, Deepak Kenchammana, Anshul Madan, and Rahul 4059 Iyer. Tom Talpey co-authored an unpublished version of that 4060 document. It was also was reviewed by a number of individuals: 4061 Pranoop Erasani, Tom Haynes, Arthur Lent, Trond Myklebust, Dave 4062 Noveck, Theresa Lingutla-Raj, Manjunath Shankararao, Satyam Vaghani, 4063 and Nico Williams. 4065 For the NFS space reservation operations, the original draft was by 4066 Mike Eisler, James Lentini, Manjunath Shankararao, and Rahul Iyer. 4068 For the sparse file support, the original draft was by Dean 4069 Hildebrand and Marc Eshel. Valuable input and advice was received 4070 from Sorin Faibish, Bruce Fields, Benny Halevy, Trond Myklebust, and 4071 Richard Scheffenegger. 4073 For the Application IO Hints, the original draft was by Dean 4074 Hildebrand, Mike Eisler, Trond Myklebust, and Sam Falkner. Some 4075 early reviwers included Benny Halevy and Pranoop Erasani. 4077 For Labeled NFS, the original draft was by David Quigley, James 4078 Morris, Jarret Lu, and Tom Haynes. Peter Staubach, Trond Myklebust, 4079 Sorrin Faibish, Nico Williams, and David Black also contributed in 4080 the final push to get this accepted. 4082 Appendix B. RFC Editor Notes 4084 [RFC Editor: please remove this section prior to publishing this 4085 document as an RFC] 4087 [RFC Editor: prior to publishing this document as an RFC, please 4088 replace all occurrences of RFCTBD10 with RFCxxxx where xxxx is the 4089 RFC number of this document] 4091 Author's Address 4093 Thomas Haynes 4094 NetApp 4095 9110 E 66th St 4096 Tulsa, OK 74133 4097 USA 4099 Phone: +1 918 307 1415 4100 Email: thomas@netapp.com 4101 URI: http://www.tulsalabs.com