idnits 2.17.1 draft-ietf-nfsv4-minorversion2-32.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 : ---------------------------------------------------------------------------- -- The document has examples using IPv4 documentation addresses according to RFC6890, but does not use any IPv6 documentation addresses. Maybe there should be IPv6 examples, too? Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (March 04, 2015) is 3341 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Looks like a reference, but probably isn't: '0' on line 3922 == Missing Reference: '32K' is mentioned on line 3922, but not defined -- Possible downref: Non-RFC (?) normative reference: ref. 'NFSv42xdr' ** Obsolete normative reference: RFC 5661 (Obsoleted by RFC 8881) == Outdated reference: A later version (-06) exists of draft-ietf-nfsv4-lfs-registry-01 -- Obsolete informational reference (is this intentional?): RFC 2401 (Obsoleted by RFC 4301) -- Obsolete informational reference (is this intentional?): RFC 2616 (Obsoleted by RFC 7230, RFC 7231, RFC 7232, RFC 7233, RFC 7234, RFC 7235) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 6 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NFSv4 T. Haynes 3 Internet-Draft Primary Data 4 Intended status: Standards Track March 04, 2015 5 Expires: September 5, 2015 7 NFS Version 4 Minor Version 2 8 draft-ietf-nfsv4-minorversion2-32.txt 10 Abstract 12 This Internet-Draft describes NFS version 4 minor version two, 13 describing the protocol extensions made from NFS version 4 minor 14 version 1. Major extensions introduced in NFS version 4 minor 15 version two include: Server Side Copy, Application I/O Advise, Space 16 Reservations, Sparse Files, Application Data Blocks, and Labeled NFS. 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 [RFC2119]. 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 September 5, 2015. 41 Copyright Notice 43 Copyright (c) 2015 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 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 59 1.1. The NFS Version 4 Minor Version 2 Protocol . . . . . . . 4 60 1.2. Scope of This Document . . . . . . . . . . . . . . . . . 5 61 1.3. NFSv4.2 Goals . . . . . . . . . . . . . . . . . . . . . . 5 62 1.4. Overview of NFSv4.2 Features . . . . . . . . . . . . . . 5 63 1.4.1. Server Side Copy . . . . . . . . . . . . . . . . . . 5 64 1.4.2. Application I/O Advise . . . . . . . . . . . . . . . 6 65 1.4.3. Sparse Files . . . . . . . . . . . . . . . . . . . . 6 66 1.4.4. Space Reservation . . . . . . . . . . . . . . . . . . 6 67 1.4.5. Application Data Block (ADB) Support . . . . . . . . 6 68 1.4.6. Labeled NFS . . . . . . . . . . . . . . . . . . . . . 6 69 1.5. Enhancements to Minor Versioning Model . . . . . . . . . 7 70 2. Minor Versioning . . . . . . . . . . . . . . . . . . . . . . 7 71 3. pNFS considerations for New Operations . . . . . . . . . . . 8 72 3.1. Atomicity for ALLOCATE and DEALLOCATE . . . . . . . . . . 8 73 3.2. Sharing of stateids with NFSv4.1 . . . . . . . . . . . . 8 74 3.3. NFSv4.2 as a Storage Protocol in pNFS: the File Layout 75 Type . . . . . . . . . . . . . . . . . . . . . . . . . . 8 76 3.3.1. Operations Sent to NFSv4.2 Data Servers . . . . . . . 8 77 4. Server Side Copy . . . . . . . . . . . . . . . . . . . . . . 9 78 4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 9 79 4.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 9 80 4.2.1. Copy Operations . . . . . . . . . . . . . . . . . . . 10 81 4.2.2. Requirements for Operations . . . . . . . . . . . . . 10 82 4.3. Requirements for Inter-Server Copy . . . . . . . . . . . 11 83 4.4. Implementation Considerations . . . . . . . . . . . . . . 11 84 4.4.1. Locking the Files . . . . . . . . . . . . . . . . . . 11 85 4.4.2. Client Caches . . . . . . . . . . . . . . . . . . . . 12 86 4.5. Intra-Server Copy . . . . . . . . . . . . . . . . . . . . 12 87 4.6. Inter-Server Copy . . . . . . . . . . . . . . . . . . . . 13 88 4.7. Server-to-Server Copy Protocol . . . . . . . . . . . . . 17 89 4.7.1. Considerations on Selecting a Copy Protocol . . . . . 17 90 4.7.2. Using NFSv4.x as the Copy Protocol . . . . . . . . . 17 91 4.7.3. Using an Alternative Copy Protocol . . . . . . . . . 17 92 4.8. netloc4 - Network Locations . . . . . . . . . . . . . . . 18 93 4.9. Copy Offload Stateids . . . . . . . . . . . . . . . . . . 19 94 4.10. Security Considerations . . . . . . . . . . . . . . . . . 19 95 4.10.1. Inter-Server Copy Security . . . . . . . . . . . . . 20 96 5. Support for Application IO Hints . . . . . . . . . . . . . . 28 97 6. Sparse Files . . . . . . . . . . . . . . . . . . . . . . . . 28 98 6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 28 99 6.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 29 100 6.3. New Operations . . . . . . . . . . . . . . . . . . . . . 29 101 6.3.1. READ_PLUS . . . . . . . . . . . . . . . . . . . . . . 29 102 6.3.2. DEALLOCATE . . . . . . . . . . . . . . . . . . . . . 30 103 7. Space Reservation . . . . . . . . . . . . . . . . . . . . . . 30 104 8. Application Data Block Support . . . . . . . . . . . . . . . 32 105 8.1. Generic Framework . . . . . . . . . . . . . . . . . . . . 33 106 8.1.1. Data Block Representation . . . . . . . . . . . . . . 33 107 8.2. An Example of Detecting Corruption . . . . . . . . . . . 34 108 8.3. Example of READ_PLUS . . . . . . . . . . . . . . . . . . 35 109 8.4. An Example of Zeroing Space . . . . . . . . . . . . . . . 36 110 9. Labeled NFS . . . . . . . . . . . . . . . . . . . . . . . . . 36 111 9.1. Introduction . . . . . . . . . . . . . . . . . . . . . . 36 112 9.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 37 113 9.3. MAC Security Attribute . . . . . . . . . . . . . . . . . 38 114 9.3.1. Delegations . . . . . . . . . . . . . . . . . . . . . 39 115 9.3.2. Permission Checking . . . . . . . . . . . . . . . . . 39 116 9.3.3. Object Creation . . . . . . . . . . . . . . . . . . . 39 117 9.3.4. Existing Objects . . . . . . . . . . . . . . . . . . 39 118 9.3.5. Label Changes . . . . . . . . . . . . . . . . . . . . 40 119 9.4. pNFS Considerations . . . . . . . . . . . . . . . . . . . 40 120 9.5. Discovery of Server Labeled NFS Support . . . . . . . . . 40 121 9.6. MAC Security NFS Modes of Operation . . . . . . . . . . . 41 122 9.6.1. Full Mode . . . . . . . . . . . . . . . . . . . . . . 41 123 9.6.2. Guest Mode . . . . . . . . . . . . . . . . . . . . . 42 124 9.7. Security Considerations for Labeled NFS . . . . . . . . . 43 125 10. Sharing change attribute implementation details with NFSv4 126 clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 127 11. Error Values . . . . . . . . . . . . . . . . . . . . . . . . 44 128 11.1. Error Definitions . . . . . . . . . . . . . . . . . . . 44 129 11.1.1. General Errors . . . . . . . . . . . . . . . . . . . 44 130 11.1.2. Server to Server Copy Errors . . . . . . . . . . . . 44 131 11.1.3. Labeled NFS Errors . . . . . . . . . . . . . . . . . 45 132 11.2. New Operations and Their Valid Errors . . . . . . . . . 45 133 11.3. New Callback Operations and Their Valid Errors . . . . . 49 134 12. New File Attributes . . . . . . . . . . . . . . . . . . . . . 50 135 12.1. New RECOMMENDED Attributes - List and Definition 136 References . . . . . . . . . . . . . . . . . . . . . . . 50 137 12.2. Attribute Definitions . . . . . . . . . . . . . . . . . 50 138 13. Operations: REQUIRED, RECOMMENDED, or OPTIONAL . . . . . . . 53 139 14. Modifications to NFSv4.1 Operations . . . . . . . . . . . . . 56 140 14.1. Operation 42: EXCHANGE_ID - Instantiate Client ID . . . 56 141 14.2. Operation 48: GETDEVICELIST - Get All Device Mappings 142 for a File System . . . . . . . . . . . . . . . . . . . 58 143 15. NFSv4.2 Operations . . . . . . . . . . . . . . . . . . . . . 59 144 15.1. Operation 59: ALLOCATE - Reserve Space in A Region of a 145 File . . . . . . . . . . . . . . . . . . . . . . . . . . 59 146 15.2. Operation 60: COPY - Initiate a server-side copy . . . . 60 147 15.3. Operation 61: COPY_NOTIFY - Notify a source server of a 148 future copy . . . . . . . . . . . . . . . . . . . . . . 65 149 15.4. Operation 62: DEALLOCATE - Unreserve Space in a Region 150 of a File . . . . . . . . . . . . . . . . . . . . . . . 67 151 15.5. Operation 63: IO_ADVISE - Application I/O access pattern 152 hints . . . . . . . . . . . . . . . . . . . . . . . . . 68 153 15.6. Operation 64: LAYOUTERROR - Provide Errors for the 154 Layout . . . . . . . . . . . . . . . . . . . . . . . . . 74 155 15.7. Operation 65: LAYOUTSTATS - Provide Statistics for the 156 Layout . . . . . . . . . . . . . . . . . . . . . . . . . 77 157 15.8. Operation 66: OFFLOAD_CANCEL - Stop an Offloaded 158 Operation . . . . . . . . . . . . . . . . . . . . . . . 78 159 15.9. Operation 67: OFFLOAD_STATUS - Poll for Status of 160 Asynchronous Operation . . . . . . . . . . . . . . . . . 79 161 15.10. Operation 68: READ_PLUS - READ Data or Holes from a File 80 162 15.11. Operation 69: SEEK - Find the Next Data or Hole . . . . 85 163 15.12. Operation 70: WRITE_SAME - WRITE an ADB Multiple Times 164 to a File . . . . . . . . . . . . . . . . . . . . . . . 86 165 16. NFSv4.2 Callback Operations . . . . . . . . . . . . . . . . . 90 166 16.1. Operation 15: CB_OFFLOAD - Report results of an 167 asynchronous operation . . . . . . . . . . . . . . . . . 90 168 17. Security Considerations . . . . . . . . . . . . . . . . . . . 91 169 18. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 92 170 19. References . . . . . . . . . . . . . . . . . . . . . . . . . 92 171 19.1. Normative References . . . . . . . . . . . . . . . . . . 92 172 19.2. Informative References . . . . . . . . . . . . . . . . . 92 173 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 94 174 Appendix B. RFC Editor Notes . . . . . . . . . . . . . . . . . . 95 175 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 95 177 1. Introduction 179 1.1. The NFS Version 4 Minor Version 2 Protocol 181 The NFS version 4 minor version 2 (NFSv4.2) protocol is the third 182 minor version of the NFS version 4 (NFSv4) protocol. The first minor 183 version, NFSv4.0, is described in [I-D.ietf-nfsv4-rfc3530bis] and the 184 second minor version, NFSv4.1, is described in [RFC5661]. 186 As a minor version, NFSv4.2 is consistent with the overall goals for 187 NFSv4, but extends the protocol so as to better meet those goals, 188 based on experiences with NFSv4.1. In addition, NFSv4.2 has adopted 189 some additional goals, which motivate some of the major extensions in 190 NFSv4.2. 192 1.2. Scope of This Document 194 This document describes the NFSv4.2 protocol. With respect to 195 NFSv4.0 and NFSv4.1, this document does not: 197 o describe the NFSv4.0 or NFSv4.1 protocols, except where needed to 198 contrast with NFSv4.2 200 o modify the specification of the NFSv4.0 or NFSv4.1 protocols 202 o clarify the NFSv4.0 or NFSv4.1 protocols. I.e., any 203 clarifications made here apply to NFSv4.2 and neither of the prior 204 protocols 206 The full External Data Representation (XDR) [RFC4506] for NFSv4.2 is 207 presented in [NFSv42xdr]. 209 1.3. NFSv4.2 Goals 211 A major goal of the design of NFSv4.2 is to take common local file 212 system features and offer them remotely. These features might 214 o already be available on the servers, e.g., sparse files 216 o be under development as a new standard, e.g., SEEK pulls in both 217 SEEK_HOLE and SEEK_DATA 219 o be used by clients with the servers via some proprietary means, 220 e.g., Labeled NFS 222 NFSv4.2 provides means for clients to leverage these features on the 223 server in cases in which that had previously not been possible within 224 the confines of the NFS protocol. 226 1.4. Overview of NFSv4.2 Features 228 1.4.1. Server Side Copy 230 A traditional file copy of a remotely accessed, whether from one 231 server to another or between location in the same server, results in 232 the data being put on the network twice - source to client and then 233 client to destination. New operations are introduced to allow 234 unnecessary traffic to be eliminated: 236 The intra-server copy feature allows the client to request the 237 server to perform the copy internally, avoiding unnecessary 238 network traffic. 240 The inter-server copy feature allows the client to authorize the 241 source and destination servers to interact directly. 243 As such copies can be lengthy, asynchronous support is also provided. 245 1.4.2. Application I/O Advise 247 Applications and clients want to advise the server as to expected I/O 248 behavior. Using IO_ADVISE (see Section 15.5) to communicate future I 249 /O behavior such as whether a file will be accessed sequentially or 250 randomly, and whether a file will or will not be accessed in the near 251 future, allows servers to optimize future I/O requests for a file by, 252 for example, prefetching or evicting data. This operation can be 253 used to support the posix_fadvise function. In addition, it may be 254 helpful to applications such as databases and video editors. 256 1.4.3. Sparse Files 258 Sparse files are ones which have unallocated or uninitialized data 259 blocks as holes in the file. Such holes are typically transferred as 260 0s during I/O. READ_PLUS (see Section 15.10) allows a server to send 261 back to the client metadata describing the hole and DEALLOCATE (see 262 Section 15.4) allows the client to punch holes into a file. In 263 addition, SEEK (see Section 15.11) is provided to scan for the next 264 hole or data from a given location. 266 1.4.4. Space Reservation 268 When a file is sparse, one concern applications have is ensuring that 269 there will always be enough data blocks available for the file during 270 future writes. ALLOCATE (see Section 15.1) allows a client to 271 request a guarantee that space will be available. Also DEALLOCATE 272 (see Section 15.4) allows the client to punch a hole into a file, 273 thus releasing a space reservation. 275 1.4.5. Application Data Block (ADB) Support 277 Some applications treat a file as if it were a disk and as such want 278 to initialize (or format) the file image. We introduce WRITE_SAME 279 (see Section 15.12) to send this metadata to the server to allow it 280 to write the block contents. 282 1.4.6. Labeled NFS 284 While both clients and servers can employ Mandatory Access Control 285 (MAC) security models to enforce data access, there has been no 286 protocol support for interoperability. A new file object attribute, 287 sec_label (see Section 12.2.2) allows for the server to store MAC 288 labels on files, which the client retrieves and uses to enforce data 289 access (see Section 9.6.2). The format of the sec_label accommodates 290 any MAC security system. 292 1.5. Enhancements to Minor Versioning Model 294 In NFSv4.1, the only way to introduce new variants of an operation 295 was to introduce a new operation. I.e., READ becomes either READ2 or 296 READ_PLUS. With the use of discriminated unions as parameters to 297 such functions in NFSv4.2, it is possible to add a new arm in a 298 subsequent minor version. And it is also possible to move such an 299 operation from OPTIONAL/RECOMMENDED to REQUIRED. Forcing an 300 implementation to adopt each arm of a discriminated union at such a 301 time does not meet the spirit of the minor versioning rules. As 302 such, new arms of a discriminated union MUST follow the same 303 guidelines for minor versioning as operations in NFSv4.1 - i.e., they 304 may not be made REQUIRED. To support this, a new error code, 305 NFS4ERR_UNION_NOTSUPP, allows the server to communicate to the client 306 that the operation is supported, but the specific arm of the 307 discriminated union is not. 309 2. Minor Versioning 311 NFSv4.2 is a minor version of NFSv4 and is built upon NFSv4.1 as 312 documented in [RFC5661] and [RFC5662]. 314 NFSv4.2 does not modify the rules applicable to the NFSv4 versioning 315 process and follows the rules set out in [RFC5661] or in standard- 316 track documents updating that document (e.g., in an RFC based on 317 [NFSv4-Versioning]). 319 NFSv4.2 only defines extensions to NFSv4.1, each of which may be 320 supported (or not) independently. It does not 322 o introduce infrastructural features 324 o make existing features MANDATORY to NOT implement 326 o change the status of existing features (i.e., by changing their 327 status among OPTIONAL, RECOMMENDED, REQUIRED). 329 The following versioning-related considerations should be noted. 331 o When a new case is added to an existing switch, servers need to 332 report non-support of that new case by returning 333 NFS4ERR_UNION_NOTSUPP. 335 o As regards the potential cross-minor-version transfer of stateids, 336 pNFS implementations of the file mapping type may support of use 337 of an NFSv4.2 metadata sever with NFSv4.1 data servers. In this 338 context, a stateid returned by an NFSv4.2 COMPOUND will be used in 339 an NFSv4.1 COMPOUND directed to the data server (see Sections 3.2 340 and 3.3). 342 3. pNFS considerations for New Operations 344 3.1. Atomicity for ALLOCATE and DEALLOCATE 346 Both ALLOCATE (see Section 15.1) and DEALLOCATE (see Section 15.4) 347 are sent to the metadata server, which is responsible for 348 coordinating the changes onto the storage devices. In particular, 349 both operations must either fully succeed or fail, it cannot be the 350 case that one storage device succeeds whilst another fails. 352 3.2. Sharing of stateids with NFSv4.1 354 A NFSv4.2 metadata server can hand out a layout to a NFSv4.1 storage 355 device. Section 13.9.1 of [RFC5661] discusses how the client gets a 356 stateid from the metadata server to present to a storage device. 358 3.3. NFSv4.2 as a Storage Protocol in pNFS: the File Layout Type 360 A file layout provided by a NFSv4.2 server may refer either to a 361 storage device that only implements NFSv4.1 as specified in 362 [RFC5661], or to a storage device that implements additions from 363 NFSv4.2, in which case the rules in Section 3.3.1 apply. As the File 364 Layout Type does not provide a means for informing the client as to 365 which minor version a particular storage device is providing, it will 366 have to negotiate this via the normal RPC semantics of major and 367 minor version discovery. 369 3.3.1. Operations Sent to NFSv4.2 Data Servers 371 In addition to the commands listed in [RFC5661], NFSv4.2 data servers 372 MAY accept a COMPOUND containing the following additional operations: 373 IO_ADVISE (see Section 15.5), READ_PLUS (see Section 15.10), 374 WRITE_SAME (see Section 15.12), and SEEK (see Section 15.11), which 375 will be treated like the subset specified as "Operations Sent to 376 NFSv4.1 Data Servers" in Section 13.6 of [RFC5661]. 378 Additional details on the implementation of these operations in a 379 pNFS context are documented in the operation specific sections. 381 4. Server Side Copy 383 4.1. Introduction 385 The server-side copy feature provides a mechanism for the NFS client 386 to perform a file copy on a server or between two servers without the 387 data being transmitted back and forth over the network through the 388 NFS client. Without this feature, an NFS client copies data from one 389 location to another by reading the data from the source server over 390 the network, and then writing the data back over the network to the 391 destination server. 393 If the source object and destination object are on different file 394 servers, the file servers will communicate with one another to 395 perform the copy operation. The server-to-server protocol by which 396 this is accomplished is not defined in this document. 398 4.2. Protocol Overview 400 The server-side copy offload operations support both intra-server and 401 inter-server file copies. An intra-server copy is a copy in which 402 the source file and destination file reside on the same server. In 403 an inter-server copy, the source file and destination file are on 404 different servers. In both cases, the copy may be performed 405 synchronously or asynchronously. 407 Throughout the rest of this document, we refer to the NFS server 408 containing the source file as the "source server" and the NFS server 409 to which the file is transferred as the "destination server". In the 410 case of an intra-server copy, the source server and destination 411 server are the same server. Therefore in the context of an intra- 412 server copy, the terms source server and destination server refer to 413 the single server performing the copy. 415 The new operations are designed to copy files. Other file system 416 objects can be copied by building on these operations or using other 417 techniques. For example, if the user wishes to copy a directory, the 418 client can synthesize a directory copy by first creating the 419 destination directory and then copying the source directory's files 420 to the new destination directory. 422 For the inter-server copy, the operations are defined to be 423 compatible with the traditional copy authentication approach. The 424 client and user are authorized at the source for reading. Then they 425 are authorized at the destination for writing. 427 4.2.1. Copy Operations 429 COPY_NOTIFY: Used by the client to notify the source server of a 430 future file copy from a given destination server for the given 431 user. (Section 15.3) 433 COPY: Used by the client to request a file copy. (Section 15.2) 435 OFFLOAD_CANCEL: Used by the client to terminate an asynchronous file 436 copy. (Section 15.8) 438 OFFLOAD_STATUS: Used by the client to poll the status of an 439 asynchronous file copy. (Section 15.9) 441 CB_OFFLOAD: Used by the destination server to report the results of 442 an asynchronous file copy to the client. (Section 16.1) 444 4.2.2. Requirements for Operations 446 The implementation of server-side copy is OPTIONAL by the client and 447 the server. However, in order to successfully copy a file, some 448 operations MUST be supported by the client and/or server. 450 If a client desires an intra-server file copy, then it MUST support 451 the COPY and CB_OFFLOAD operations. If COPY returns a stateid, then 452 the client MAY use the OFFLOAD_CANCEL and OFFLOAD_STATUS operations. 454 If a client desires an inter-server file copy, then it MUST support 455 the COPY, COPY_NOTIFY, and CB_OFFLOAD operations, and MAY use the 456 OFFLOAD_CANCEL operation. If COPY returns a stateid, then the client 457 MAY use the OFFLOAD_CANCEL and OFFLOAD_STATUS operations. 459 If a server supports intra-server copy, then the server MUST support 460 the COPY operation. If a server's COPY operation returns a stateid, 461 then the server MUST also support these operations: CB_OFFLOAD, 462 OFFLOAD_CANCEL, and OFFLOAD_STATUS. 464 If a source server supports inter-server copy, then the source server 465 MUST support all these operations: COPY_NOTIFY and OFFLOAD_CANCEL. 466 If a destination server supports inter-server copy, then the 467 destination server MUST support the COPY operation. If a destination 468 server's COPY operation returns a stateid, then the destination 469 server MUST also support these operations: CB_OFFLOAD, 470 OFFLOAD_CANCEL, COPY_NOTIFY, and OFFLOAD_STATUS. 472 Each operation is performed in the context of the user identified by 473 the ONC RPC credential of its containing COMPOUND or CB_COMPOUND 474 request. For example, an OFFLOAD_CANCEL operation issued by a given 475 user indicates that a specified COPY operation initiated by the same 476 user be canceled. Therefore an OFFLOAD_CANCEL MUST NOT interfere 477 with a copy of the same file initiated by another user. 479 An NFS server MAY allow an administrative user to monitor or cancel 480 copy operations using an implementation specific interface. 482 4.3. Requirements for Inter-Server Copy 484 Inter-server copy is driven by several requirements: 486 o The specification MUST NOT mandate the server-to-server protocol. 488 o The specification MUST provide guidance for using NFSv4.x as a 489 copy protocol. For those source and destination servers willing 490 to use NFSv4.x, there are specific security considerations that 491 this specification MUST address. 493 o The specification MUST NOT mandate preconfiguration between the 494 source and destination server. Requiring that the source and 495 destination first have a "copying relationship" increases the 496 administrative burden. However the specification MUST NOT 497 preclude implementations that require preconfiguration. 499 o The specification MUST NOT mandate a trust relationship between 500 the source and destination server. The NFSv4 security model 501 requires mutual authentication between a principal on an NFS 502 client and a principal on an NFS server. This model MUST continue 503 with the introduction of COPY. 505 4.4. Implementation Considerations 507 4.4.1. Locking the Files 509 Both the source and destination file may need to be locked to protect 510 the content during the copy operations. A client can achieve this by 511 a combination of OPEN and LOCK operations. I.e., either share or 512 byte range locks might be desired. 514 Note that when the client establishes a lock stateid on the source, 515 the context of that stateid is for the client and not the 516 destination. As such, there might already be an outstanding stateid, 517 issued to the destination as client of the source, with the same 518 value as that provided for the lock stateid. The source MUST equate 519 the lock stateid as that of the client, i.e., when the destination 520 presents it in the context of a inter-server copy, it is on behalf of 521 the client. 523 4.4.2. Client Caches 525 In a traditional copy, if the client is in the process of writing to 526 the file before the copy (and perhaps with a write delegation), it 527 will be straightforward to update the destination server. With an 528 inter-server copy, the source has no insight into the changes cached 529 on the client. The client SHOULD write back the data to the source. 530 If it does not do so, it is possible that the destination will 531 receive a corrupt copy of file. 533 4.5. Intra-Server Copy 535 To copy a file on a single server, the client uses a COPY operation. 536 The server may respond to the copy operation with the final results 537 of the copy or it may perform the copy asynchronously and deliver the 538 results using a CB_OFFLOAD operation callback. If the copy is 539 performed asynchronously, the client may poll the status of the copy 540 using OFFLOAD_STATUS or cancel the copy using OFFLOAD_CANCEL. 542 A synchronous intra-server copy is shown in Figure 1. In this 543 example, the NFS server chooses to perform the copy synchronously. 544 The copy operation is completed, either successfully or 545 unsuccessfully, before the server replies to the client's request. 546 The server's reply contains the final result of the operation. 548 Client Server 549 + + 550 | | 551 |--- OPEN ---------------------------->| Client opens 552 |<------------------------------------/| the source file 553 | | 554 |--- OPEN ---------------------------->| Client opens 555 |<------------------------------------/| the destination file 556 | | 557 |--- COPY ---------------------------->| Client requests 558 |<------------------------------------/| a file copy 559 | | 560 |--- CLOSE --------------------------->| Client closes 561 |<------------------------------------/| the destination file 562 | | 563 |--- CLOSE --------------------------->| Client closes 564 |<------------------------------------/| the source file 565 | | 566 | | 568 Figure 1: A synchronous intra-server copy. 570 An asynchronous intra-server copy is shown in Figure 2. In this 571 example, the NFS server performs the copy asynchronously. The 572 server's reply to the copy request indicates that the copy operation 573 was initiated and the final result will be delivered at a later time. 574 The server's reply also contains a copy stateid. The client may use 575 this copy stateid to poll for status information (as shown) or to 576 cancel the copy using an OFFLOAD_CANCEL. When the server completes 577 the copy, the server performs a callback to the client and reports 578 the results. 580 Client Server 581 + + 582 | | 583 |--- OPEN ---------------------------->| Client opens 584 |<------------------------------------/| the source file 585 | | 586 |--- OPEN ---------------------------->| Client opens 587 |<------------------------------------/| the destination file 588 | | 589 |--- COPY ---------------------------->| Client requests 590 |<------------------------------------/| a file copy 591 | | 592 | | 593 |--- OFFLOAD_STATUS ------------------>| Client may poll 594 |<------------------------------------/| for status 595 | | 596 | . | Multiple OFFLOAD_STATUS 597 | . | operations may be sent. 598 | . | 599 | | 600 |<-- CB_OFFLOAD -----------------------| Server reports results 601 |\------------------------------------>| 602 | | 603 |--- CLOSE --------------------------->| Client closes 604 |<------------------------------------/| the destination file 605 | | 606 |--- CLOSE --------------------------->| Client closes 607 |<------------------------------------/| the source file 608 | | 609 | | 611 Figure 2: An asynchronous intra-server copy. 613 4.6. Inter-Server Copy 615 A copy may also be performed between two servers. The copy protocol 616 is designed to accommodate a variety of network topologies. As shown 617 in Figure 3, the client and servers may be connected by multiple 618 networks. In particular, the servers may be connected by a 619 specialized, high speed network (network 192.0.2.0/24 in the diagram) 620 that does not include the client. The protocol allows the client to 621 setup the copy between the servers (over network 203.0.113.0/24 in 622 the diagram) and for the servers to communicate on the high speed 623 network if they choose to do so. 625 192.0.2.0/24 626 +-------------------------------------+ 627 | | 628 | | 629 | 192.0.2.18 | 192.0.2.56 630 +-------+------+ +------+------+ 631 | Source | | Destination | 632 +-------+------+ +------+------+ 633 | 203.0.113.18 | 203.0.113.56 634 | | 635 | | 636 | 203.0.113.0/24 | 637 +------------------+------------------+ 638 | 639 | 640 | 203.0.113.243 641 +-----+-----+ 642 | Client | 643 +-----------+ 645 Figure 3: An example inter-server network topology. 647 For an inter-server copy, the client notifies the source server that 648 a file will be copied by the destination server using a COPY_NOTIFY 649 operation. The client then initiates the copy by sending the COPY 650 operation to the destination server. The destination server may 651 perform the copy synchronously or asynchronously. 653 A synchronous inter-server copy is shown in Figure 4. In this case, 654 the destination server chooses to perform the copy before responding 655 to the client's COPY request. 657 An asynchronous copy is shown in Figure 5. In this case, the 658 destination server chooses to respond to the client's COPY request 659 immediately and then perform the copy asynchronously. 661 Client Source Destination 662 + + + 663 | | | 664 |--- OPEN --->| | Returns os1 665 |<------------------/| | 666 | | | 667 |--- COPY_NOTIFY --->| | 668 |<------------------/| | 669 | | | 670 |--- OPEN ---------------------------->| Returns os2 671 |<------------------------------------/| 672 | | | 673 |--- COPY ---------------------------->| 674 | | | 675 | | | 676 | |<----- read -----| 677 | |\--------------->| 678 | | | 679 | | . | Multiple reads may 680 | | . | be necessary 681 | | . | 682 | | | 683 | | | 684 |<------------------------------------/| Destination replies 685 | | | to COPY 686 | | | 687 |--- CLOSE --------------------------->| Release open state 688 |<------------------------------------/| 689 | | | 690 |--- CLOSE --->| | Release open state 691 |<------------------/| | 693 Figure 4: A synchronous inter-server copy. 695 Client Source Destination 696 + + + 697 | | | 698 |--- OPEN --->| | Returns os1 699 |<------------------/| | 700 | | | 701 |--- LOCK --->| | Optional, could be done 702 |<------------------/| | with a share lock 703 | | | 704 |--- COPY_NOTIFY --->| | Need to pass in 705 |<------------------/| | os1 or lock state 706 | | | 707 | | | 708 | | | 709 |--- OPEN ---------------------------->| Returns os2 710 |<------------------------------------/| 711 | | | 712 |--- LOCK ---------------------------->| Optional ... 713 |<------------------------------------/| 714 | | | 715 |--- COPY ---------------------------->| Need to pass in 716 |<------------------------------------/| os2 or lock state 717 | | | 718 | | | 719 | |<----- read -----| 720 | |\--------------->| 721 | | | 722 | | . | Multiple reads may 723 | | . | be necessary 724 | | . | 725 | | | 726 | | | 727 |--- OFFLOAD_STATUS ------------------>| Client may poll 728 |<------------------------------------/| for status 729 | | | 730 | | . | Multiple OFFLOAD_STATUS 731 | | . | operations may be sent 732 | | . | 733 | | | 734 | | | 735 | | | 736 |<-- CB_OFFLOAD -----------------------| Destination reports 737 |\------------------------------------>| results 738 | | | 739 |--- LOCKU --------------------------->| Only if LOCK was done 740 |<------------------------------------/| 741 | | | 742 |--- CLOSE --------------------------->| Release open state 743 |<------------------------------------/| 744 | | | 745 |--- LOCKU --->| | Only if LOCK was done 746 |<------------------/| | 747 | | | 748 |--- CLOSE --->| | Release open state 749 |<------------------/| | 750 | | | 752 Figure 5: An asynchronous inter-server copy. 754 4.7. Server-to-Server Copy Protocol 756 The choice of what protocol to use in an inter-server copy is 757 ultimately the destination server's decision. However, the 758 destination server has to be cognizant that it is working on behalf 759 of the client. 761 4.7.1. Considerations on Selecting a Copy Protocol 763 The client can have requirements over both the size of transactions 764 and error recovery semantics. It may want to split the copy up such 765 that each chunk is synchronously transferred. It may want the copy 766 protocol to copy the bytes in consecutive order such that upon an 767 error, the client can restart the copy at the last known good offset. 768 If the destination server cannot meet these requirements, the client 769 may prefer the traditional copy mechanism such that it can meet those 770 requirements. 772 4.7.2. Using NFSv4.x as the Copy Protocol 774 The destination server MAY use standard NFSv4.x (where x >= 1) 775 operations to read the data from the source server. If NFSv4.x is 776 used for the server-to-server copy protocol, the destination server 777 can use the source filehandle and ca_src_stateid provided in the COPY 778 request with standard NFSv4.x operations to read data from the source 779 server. Note that the ca_src_stateid MUST be the cnr_stateid 780 returned from the source via the COPY_NOTIFY. 782 4.7.3. Using an Alternative Copy Protocol 784 In a homogeneous environment, the source and destination servers 785 might be able to perform the file copy extremely efficiently using 786 specialized protocols. For example the source and destination 787 servers might be two nodes sharing a common file system format for 788 the source and destination file systems. Thus the source and 789 destination are in an ideal position to efficiently render the image 790 of the source file to the destination file by replicating the file 791 system formats at the block level. Another possibility is that the 792 source and destination might be two nodes sharing a common storage 793 area network, and thus there is no need to copy any data at all, and 794 instead ownership of the file and its contents might simply be re- 795 assigned to the destination. To allow for these possibilities, the 796 destination server is allowed to use a server-to-server copy protocol 797 of its choice. 799 In a heterogeneous environment, using a protocol other than NFSv4.x 800 (e.g., HTTP [RFC2616] or FTP [RFC959]) presents some challenges. In 801 particular, the destination server is presented with the challenge of 802 accessing the source file given only an NFSv4.x filehandle. 804 One option for protocols that identify source files with path names 805 is to use an ASCII hexadecimal representation of the source 806 filehandle as the file name. 808 Another option for the source server is to use URLs to direct the 809 destination server to a specialized service. For example, the 810 response to COPY_NOTIFY could include the URL ftp:// 811 s1.example.com:9999/_FH/0x12345, where 0x12345 is the ASCII 812 hexadecimal representation of the source filehandle. When the 813 destination server receives the source server's URL, it would use 814 "_FH/0x12345" as the file name to pass to the FTP server listening on 815 port 9999 of s1.example.com. On port 9999 there would be a special 816 instance of the FTP service that understands how to convert NFS 817 filehandles to an open file descriptor (in many operating systems, 818 this would require a new system call, one which is the inverse of the 819 makefh() function that the pre-NFSv4 MOUNT service needs). 821 Authenticating and identifying the destination server to the source 822 server is also a challenge. Recommendations for how to accomplish 823 this are given in Section 4.10.1.3. 825 4.8. netloc4 - Network Locations 827 The server-side copy operations specify network locations using the 828 netloc4 data type shown below: 830 832 enum netloc_type4 { 833 NL4_NAME = 0, 834 NL4_URL = 1, 835 NL4_NETADDR = 2 836 }; 837 union netloc4 switch (netloc_type4 nl_type) { 838 case NL4_NAME: utf8str_cis nl_name; 839 case NL4_URL: utf8str_cis nl_url; 840 case NL4_NETADDR: netaddr4 nl_addr; 841 }; 843 845 If the netloc4 is of type NL4_NAME, the nl_name field MUST be 846 specified as a UTF-8 string. The nl_name is expected to be resolved 847 to a network address via DNS, LDAP, NIS, /etc/hosts, or some other 848 means. If the netloc4 is of type NL4_URL, a server URL [RFC3986] 849 appropriate for the server-to-server copy operation is specified as a 850 UTF-8 string. If the netloc4 is of type NL4_NETADDR, the nl_addr 851 field MUST contain a valid netaddr4 as defined in Section 3.3.9 of 852 [RFC5661]. 854 When netloc4 values are used for an inter-server copy as shown in 855 Figure 3, their values may be evaluated on the source server, 856 destination server, and client. The network environment in which 857 these systems operate should be configured so that the netloc4 values 858 are interpreted as intended on each system. 860 4.9. Copy Offload Stateids 862 A server may perform a copy offload operation asynchronously. An 863 asynchronous copy is tracked using a copy offload stateid. Copy 864 offload stateids are included in the COPY, OFFLOAD_CANCEL, 865 OFFLOAD_STATUS, and CB_OFFLOAD operations. 867 A copy offload stateid will be valid until either (A) the client or 868 server restarts or (B) the client returns the resource by issuing a 869 OFFLOAD_CANCEL operation or the client replies to a CB_OFFLOAD 870 operation. 872 A copy offload stateid's seqid MUST NOT be 0. In the context of a 873 copy offload operation, it is ambiguous to indicate the most recent 874 copy offload operation using a stateid with seqid of 0. Therefore a 875 copy offload stateid with seqid of 0 MUST be considered invalid. 877 4.10. Security Considerations 879 The security considerations pertaining to NFSv4.1 [RFC5661] apply to 880 this section. And as such, the standard security mechanisms used by 881 the protocol can be used to secure the server-to-server operations. 883 NFSv4 clients and servers supporting the inter-server copy operations 884 described in this chapter are REQUIRED to implement the mechanism 885 described in Section 4.10.1.1, and to support rejecting COPY_NOTIFY 886 requests that do not use RPCSEC_GSS with privacy. If the server-to- 887 server copy protocol is ONC RPC based, the servers are also REQUIRED 888 to implement [rpcsec_gssv3] including the RPCSEC_GSSv3 copy_to_auth, 889 copy_from_auth, and copy_confirm_auth structured privileges. This 890 requirement to implement is not a requirement to use; for example, a 891 server may depending on configuration also allow COPY_NOTIFY requests 892 that use only AUTH_SYS. 894 4.10.1. Inter-Server Copy Security 896 4.10.1.1. Inter-Server Copy via ONC RPC with RPCSEC_GSSv3 898 When the client sends a COPY_NOTIFY to the source server to expect 899 the destination to attempt to copy data from the source server, it is 900 expected that this copy is being done on behalf of the principal 901 (called the "user principal") that sent the RPC request that encloses 902 the COMPOUND procedure that contains the COPY_NOTIFY operation. The 903 user principal is identified by the RPC credentials. A mechanism 904 that allows the user principal to authorize the destination server to 905 perform the copy, that lets the source server properly authenticate 906 the destination's copy, and does not allow the destination server to 907 exceed this authorization, is necessary. 909 An approach that sends delegated credentials of the client's user 910 principal to the destination server is not used for the following 911 reason. If the client's user delegated its credentials, the 912 destination would authenticate as the user principal. If the 913 destination were using the NFSv4 protocol to perform the copy, then 914 the source server would authenticate the destination server as the 915 user principal, and the file copy would securely proceed. However, 916 this approach would allow the destination server to copy other files. 917 The user principal would have to trust the destination server to not 918 do so. This is counter to the requirements, and therefore is not 919 considered. 921 Instead, a feature of the RPCSEC_GSSv3 [rpcsec_gssv3] protocol can be 922 used: RPC application defined structured privilege assertion. This 923 features allow the destination server to authenticate to the source 924 server as acting on behalf of the user principal, and to authorize 925 the destination server to perform READs of the file to be copied from 926 the source on behalf of the user principal. Once the copy is 927 complete, the client can destroy the RPCSEC_GSSv3 handles to end the 928 authorization of both the source and destination servers to copy. 930 We define three RPCSEC_GSSv3 structured privilege assertions that 931 work in tandem to authorize the copy: 933 copy_from_auth: A user principal is authorizing a source principal 934 ("nfs@") to allow a destination principal 935 ("nfs@") to setup the copy_confirm_auth privilege 936 required to copy a file from the source to the destination on 937 behalf of the user principal. This privilege is established on 938 the source server before the user principal sends a COPY_NOTIFY 939 operation to the source server, and the resultant RPCSEC_GSSv3 940 context is used to secure the COPY_NOTIFY operation. 942 944 struct copy_from_auth_priv { 945 secret4 cfap_shared_secret; 946 netloc4 cfap_destination; 947 /* the NFSv4 user name that the user principal maps to */ 948 utf8str_mixed cfap_username; 949 }; 951 953 cfp_shared_secret is an automatically generated random number 954 secret value. 956 copy_to_auth: A user principal is authorizing a destination 957 principal ("nfs@") to setup a copy_confirm_auth 958 privilege with a source principal ("nfs@") to allow it to 959 copy a file from the source to the destination on behalf of the 960 user principal. This privilege is established on the destination 961 server before the user principal sends a COPY operation to the 962 destination server, and the resultant RPCSEC_GSSv3 context is used 963 to secure the COPY operation. 965 967 struct copy_to_auth_priv { 968 /* equal to cfap_shared_secret */ 969 secret4 ctap_shared_secret; 970 netloc4 ctap_source<>; 971 /* the NFSv4 user name that the user principal maps to */ 972 utf8str_mixed ctap_username; 973 }; 975 977 ctap_shared_secret is the automatically generated secret value 978 used to establish the copy_from_auth privilege with the source 979 principal. See Section 4.10.1.1.1. 981 copy_confirm_auth: A destination principal ("nfs@") is 982 confirming with the source principal ("nfs@") that it is 983 authorized to copy data from the source. This privilege is 984 established on the destination server before the file is copied 985 from the source to the destination. The resultant RPCSEC_GSSv3 986 context is used to secure the READ operations from the source to 987 the destination server. 989 991 struct copy_confirm_auth_priv { 992 /* equal to GSS_GetMIC() of cfap_shared_secret */ 993 opaque ccap_shared_secret_mic<>; 994 /* the NFSv4 user name that the user principal maps to */ 995 utf8str_mixed ccap_username; 996 }; 998 1000 4.10.1.1.1. Establishing a Security Context 1002 When the user principal wants to COPY a file between two servers, if 1003 it has not established copy_from_auth and copy_to_auth privileges on 1004 the servers, it establishes them: 1006 o As noted in [rpcsec_gssv3] the client uses an existing 1007 RPCSEC_GSSv3 context termed the "parent" handle to establish and 1008 protect RPCSEC_GSSv3 structured privilege assertion exchanges. 1009 The copy_from_auth privilege will use the context established 1010 between the user principal and the source server used to OPEN the 1011 source file as the RPCSEC_GSSv3 parent handle. The copy_to_auth 1012 privilege will use the context established between the user 1013 principal and the destination server used to OPEN the destination 1014 file as the RPCSEC_GSSv3 parent handle. 1016 o A random number is generated to use as a secret to be shared 1017 between the two servers. This shared secret will be placed in the 1018 cfap_shared_secret and ctap_shared_secret fields of the 1019 appropriate privilege data types, copy_from_auth_priv and 1020 copy_to_auth_priv. Because of this shared_secret the 1021 RPCSEC_GSS3_CREATE control messages for copy_from_auth and 1022 copy_to_auth MUST use a QOP of rpc_gss_svc_privacy. 1024 o An instance of copy_from_auth_priv is filled in with the shared 1025 secret, the destination server, and the NFSv4 user id of the user 1026 principal and is placed in rpc_gss3_create_args 1027 assertions[0].privs.privilege. The string "copy_from_auth" is 1028 placed in assertions[0].privs.name. The source server unwraps the 1029 rpc_gss_svc_privacy RPCSEC_GSS3_CREATE payload and verifies that 1030 the NFSv4 user id being asserted matches the source server's 1031 mapping of the user principal. If it does, the privilege is 1032 established on the source server as: <"copy_from_auth", user id, 1033 destination>. The field "handle" in a successful reply is the 1034 RPCSEC_GSSv3 copy_from_auth "child" handle that the client will 1035 use on COPY_NOTIFY requests to the source server. 1037 o An instance of copy_to_auth_priv is filled in with the shared 1038 secret, the cnr_source_server list returned by COPY_NOTIFY, and 1039 the NFSv4 user id of the user principal. The copy_to_auth_priv 1040 instance is placed in rpc_gss3_create_args 1041 assertions[0].privs.privilege. The string "copy_to_auth" is 1042 placed in assertions[0].privs.name. The destination server 1043 unwraps the rpc_gss_svc_privacy RPCSEC_GSS3_CREATE payload and 1044 verifies that the NFSv4 user id being asserted matches the 1045 destination server's mapping of the user principal. If it does, 1046 the privilege is established on the destination server as: 1047 <"copy_to_auth", user id, source list>. The field "handle" in a 1048 successful reply is the RPCSEC_GSSv3 copy_to_auth "child" handle 1049 that the client will use on COPY requests to the destination 1050 server involving the source server. 1052 As noted in [rpcsec_gssv3] Section 2.3.1 "Create Request", both the 1053 client and the source server should associate the RPCSEC_GSSv3 1054 "child" handle with the parent RPCSEC_GSSv3 handle used to create the 1055 RPCSEC_GSSv3 child handle. 1057 4.10.1.1.2. Starting a Secure Inter-Server Copy 1059 When the client sends a COPY_NOTIFY request to the source server, it 1060 uses the privileged "copy_from_auth" RPCSEC_GSSv3 handle. 1061 cna_destination_server in COPY_NOTIFY MUST be the same as 1062 cfap_destination specified in copy_from_auth_priv. Otherwise, 1063 COPY_NOTIFY will fail with NFS4ERR_ACCESS. The source server 1064 verifies that the privilege <"copy_from_auth", user id, destination> 1065 exists, and annotates it with the source filehandle, if the user 1066 principal has read access to the source file, and if administrative 1067 policies give the user principal and the NFS client read access to 1068 the source file (i.e., if the ACCESS operation would grant read 1069 access). Otherwise, COPY_NOTIFY will fail with NFS4ERR_ACCESS. 1071 When the client sends a COPY request to the destination server, it 1072 uses the privileged "copy_to_auth" RPCSEC_GSSv3 handle. 1073 ca_source_server list in COPY MUST be the same as ctap_source list 1074 specified in copy_to_auth_priv. Otherwise, COPY will fail with 1075 NFS4ERR_ACCESS. The destination server verifies that the privilege 1076 <"copy_to_auth", user id, source list> exists, and annotates it with 1077 the source and destination filehandles. If the COPY returns a 1078 wr_callback_id, then this is an asynchronous copy and the 1079 wr_callback_id must also must be annotated to the copy_to_auth 1080 privilege. If the client has failed to establish the "copy_to_auth" 1081 privilege it will reject the request with NFS4ERR_PARTNER_NO_AUTH. 1083 If either the COPY_NOTIFY, or the COPY operations fail, the 1084 associated "copy_from_auth" and "copy_to_auth" RPCSEC_GSSv3 handles 1085 MUST be destroyed. 1087 4.10.1.1.3. Securing ONC RPC Server-to-Server Copy Protocols 1089 After a destination server has a "copy_to_auth" privilege established 1090 on it, and it receives a COPY request, if it knows it will use an ONC 1091 RPC protocol to copy data, it will establish a "copy_confirm_auth" 1092 privilege on the source server prior to responding to the COPY 1093 operation as follows: 1095 o Before establishing an RPCSEC_GSSv3 context, a parent context 1096 needs to exist between nfs@ as the initiator 1097 principal, and nfs@ as the target principal. If NFS is to 1098 be used as the copy protocol, this means that the destination 1099 server must mount the source server using RPCSEC_GSSv3. 1101 o An instance of copy_confirm_auth_priv is filled in with 1102 information from the established "copy_to_auth" privilege. The 1103 value of the field ccap_shared_secret_mic is a GSS_GetMIC() of the 1104 ctap_shared_secret in the copy_to_auth privilege using the parent 1105 handle context. The field ccap_username is the mapping of the 1106 user principal to an NFSv4 user name ("user"@"domain" form), and 1107 MUST be the same as the ctap_username in the copy_to_auth 1108 privilege. The copy_confirm_auth_priv instance is placed in 1109 rpc_gss3_create_args assertions[0].privs.privilege. The string 1110 "copy_confirm_auth" is placed in assertions[0].privs.name. 1112 o The RPCSEC_GSS3_CREATE copy_from_auth message is sent to the 1113 source server with a QOP of rpc_gss_svc_privacy. The source 1114 server unwraps the rpc_gss_svc_privacy RPCSEC_GSS3_CREATE payload 1115 and verifies the cap_shared_secret_mic by calling GSS_VerifyMIC() 1116 using the parent context on the cfap_shared_secret from the 1117 established "copy_from_auth" privilege, and verifies the that the 1118 ccap_username equals the cfap_username. 1120 o If all verification succeeds, the "copy_confirm_auth" privilege is 1121 established on the source server as < "copy_confirm_auth", 1122 shared_secret_mic, user id> Because the shared secret has been 1123 verified, the resultant copy_confirm_auth RPCSEC_GSSv3 child 1124 handle is noted to be acting on behalf of the user principal. 1126 o If the source server fails to verify the copy_from_auth privilege 1127 the COPY operation will be rejected with NFS4ERR_PARTNER_NO_AUTH, 1128 causing in turn the client to destroy the associated 1129 copy_from_auth and copy_to_auth RPCSEC_GSSv3 structured privilege 1130 assertion handles. 1132 o All subsequent ONC RPC READ requests sent from the destination to 1133 copy data from the source to the destination will use the 1134 RPCSEC_GSSv3 copy_confirm_auth child handle. 1136 Note that the use of the "copy_confirm_auth" privilege accomplishes 1137 the following: 1139 o If a protocol like NFS is being used, with export policies, export 1140 policies can be overridden in case the destination server as-an- 1141 NFS-client is not authorized 1143 o Manual configuration to allow a copy relationship between the 1144 source and destination is not needed. 1146 4.10.1.1.4. Maintaining a Secure Inter-Server Copy 1148 If the client determines that either the copy_from_auth or the 1149 copy_to_auth handle becomes invalid during a copy, then the copy MUST 1150 be aborted by the client sending an OFFLOAD_CANCEL to both the source 1151 and destination servers and destroying the respective copy related 1152 context handles as described in Section 4.10.1.1.5. 1154 4.10.1.1.5. Finishing or Stopping a Secure Inter-Server Copy 1156 Under normal operation, the client MUST destroy the copy_from_auth 1157 and the copy_to_auth RPCSEC_GSSv3 handle once the COPY operation 1158 returns for a synchronous inter-server copy or a CB_OFFLOAD reports 1159 the result of an asynchronous copy. 1161 The copy_confirm_auth privilege constructed from information held by 1162 the copy_to_auth privilege, and MUST be destroyed by the destination 1163 server (via an RPCSEC_GSS3_DESTROY call) when the copy_to_auth 1164 RPCSEC_GSSv3 handle is destroyed. 1166 The copy_confirm_auth RPCSEC_GSS3 handle is associated with a 1167 copy_from_auth RPCSEC_GSS3 handle on the source server via the shared 1168 secret and MUST be locally destroyed (there is no RPCSEC_GSS3_DESTROY 1169 as the source server is not the initiator) when the copy_from_auth 1170 RPCSEC_GSSv3 handle is destroyed. 1172 If the client sends an OFFLOAD_CANCEL to the source server to rescind 1173 the destination server's synchronous copy privilege, it uses the 1174 privileged "copy_from_auth" RPCSEC_GSSv3 handle and the 1175 cra_destination_server in OFFLOAD_CANCEL MUST be the same as the name 1176 of the destination server specified in copy_from_auth_priv. The 1177 source server will then delete the <"copy_from_auth", user id, 1178 destination> privilege and fail any subsequent copy requests sent 1179 under the auspices of this privilege from the destination server. 1180 The client MUST destroy both the "copy_from_auth" and the 1181 "copy_to_auth" RPCSEC_GSSv3 handles. 1183 If the client sends an OFFLOAD_STATUS to the destination server to 1184 check on the status of an asynchronous copy, it uses the privileged 1185 "copy_to_auth" RPCSEC_GSSv3 handle and the osa_stateid in 1186 OFFLOAD_STATUS MUST be the same as the wr_callback_id specified in 1187 the "copy_to_auth" privilege stored on the destination server. 1189 If the client sends an OFFLOAD_CANCEL to the destination server to 1190 cancel an asynchronous copy, it uses the privileged "copy_to_auth" 1191 RPCSEC_GSSv3 handle and the oaa_stateid in OFFLOAD_CANCEL MUST be the 1192 same as the wr_callback_id specified in the "copy_to_auth" privilege 1193 stored on the destination server. The destination server will then 1194 delete the <"copy_to_auth", user id, source list, nounce, nounce MIC, 1195 context handle, handle version> privilege and the associated 1196 "copy_confirm_auth" RPCSEC_GSSv3 handle. The client MUST destroy 1197 both the copy_to_auth and copy_from_auth RPCSEC_GSSv3 handles. 1199 4.10.1.2. Inter-Server Copy via ONC RPC without RPCSEC_GSS 1201 ONC RPC security flavors other than RPCSEC_GSS MAY be used with the 1202 server-side copy offload operations described in this chapter. In 1203 particular, host-based ONC RPC security flavors such as AUTH_NONE and 1204 AUTH_SYS MAY be used. If a host-based security flavor is used, a 1205 minimal level of protection for the server-to-server copy protocol is 1206 possible. 1208 In the absence of a strong security mechanism designed for the 1209 purpose, the challenge is how the source server and destination 1210 server identify themselves to each other, especially in the presence 1211 of multi-homed source and destination servers. In a multi-homed 1212 environment, the destination server might not contact the source 1213 server from the same network address specified by the client in the 1214 COPY_NOTIFY. This can be overcome using the procedure described 1215 below. 1217 When the client sends the source server the COPY_NOTIFY operation, 1218 the source server may reply to the client with a list of target 1219 addresses, names, and/or URLs and assign them to the unique 1220 quadruple: . If the destination uses one of these target netlocs to contact 1222 the source server, the source server will be able to uniquely 1223 identify the destination server, even if the destination server does 1224 not connect from the address specified by the client in COPY_NOTIFY. 1225 The level of assurance in this identification depends on the 1226 unpredictability, strength and secrecy of the random number. 1228 For example, suppose the network topology is as shown in Figure 3. 1229 If the source filehandle is 0x12345, the source server may respond to 1230 a COPY_NOTIFY for destination 203.0.113.56 with the URLs: 1232 nfs://203.0.113.18//_COPY/FvhH1OKbu8VrxvV1erdjvR7N/203.0.113.56/ 1233 _FH/0x12345 1235 nfs://192.0.2.18//_COPY/FvhH1OKbu8VrxvV1erdjvR7N/203.0.113.56/_FH/ 1236 0x12345 1238 The name component after _COPY is 24 characters of base 64, more than 1239 enough to encode a 128 bit random number. 1241 The client will then send these URLs to the destination server in the 1242 COPY operation. Suppose that the 192.0.2.0/24 network is a high 1243 speed network and the destination server decides to transfer the file 1244 over this network. If the destination contacts the source server 1245 from 192.0.2.56 over this network using NFSv4.1, it does the 1246 following: 1248 COMPOUND { PUTROOTFH, LOOKUP "_COPY" ; LOOKUP 1249 "FvhH1OKbu8VrxvV1erdjvR7N" ; LOOKUP "203.0.113.56"; LOOKUP "_FH" ; 1250 OPEN "0x12345" ; GETFH } 1252 Provided that the random number is unpredictable and has been kept 1253 secret by the parties involved, the source server will therefore know 1254 that these NFSv4.x operations are being issued by the destination 1255 server identified in the COPY_NOTIFY. This random number technique 1256 only provides initial authentication of the destination server, and 1257 cannot defend against man-in-the-middle attacks after authentication 1258 or an eavesdropper that observes the random number on the wire. 1259 Other secure communication techniques (e.g., IPsec) are necessary to 1260 block these attacks. 1262 Note that the cnr_stateid returned from the COPY_NOTIFY can be used 1263 to uiniquely identify the destination server to the source server. 1264 Part of this stateid could be randomly generated in the same manner 1265 and the destination server could avoid using the above URL and 1266 instead open the file directly via NFSv4.x (where x >= 1) using a 1267 CLAIM_FH on the OPEN (see Section 18.16.3 of [RFC5661]). 1269 Servers SHOULD reject COPY_NOTIFY requests that do not use RPCSEC_GSS 1270 with privacy, thus ensuring the URL in the COPY_NOTIFY reply is 1271 encrypted. For the same reason, clients SHOULD send COPY requests to 1272 the destination using RPCSEC_GSS with privacy. 1274 4.10.1.3. Inter-Server Copy without ONC RPC 1276 The same techniques as Section 4.10.1.2, using unique URLs for each 1277 destination server, can be used for other protocols (e.g., HTTP 1278 [RFC2616] and FTP [RFC959]) as well. 1280 5. Support for Application IO Hints 1282 Applications can issue client I/O hints via posix_fadvise() 1283 [posix_fadvise] to the NFS client. While this can help the NFS 1284 client optimize I/O and caching for a file, it does not allow the NFS 1285 server and its exported file system to do likewise. We add an 1286 IO_ADVISE procedure (Section 15.5) to communicate the client file 1287 access patterns to the NFS server. The NFS server upon receiving a 1288 IO_ADVISE operation MAY choose to alter its I/O and caching behavior, 1289 but is under no obligation to do so. 1291 Application specific NFS clients such as those used by hypervisors 1292 and databases can also leverage application hints to communicate 1293 their specialized requirements. 1295 6. Sparse Files 1297 6.1. Introduction 1299 A sparse file is a common way of representing a large file without 1300 having to utilize all of the disk space for it. Consequently, a 1301 sparse file uses less physical space than its size indicates. This 1302 means the file contains 'holes', byte ranges within the file that 1303 contain no data. Most modern file systems support sparse files, 1304 including most UNIX file systems and NTFS, but notably not Apple's 1305 HFS+. Common examples of sparse files include Virtual Machine (VM) 1306 OS/disk images, database files, log files, and even checkpoint 1307 recovery files most commonly used by the HPC community. 1309 In addition many modern file systems support the concept of 1310 'unwritten' or 'uninitialized' blocks, which have uninitialized space 1311 allocated to them on disk, but will return zeros until data is 1312 written to them. Such functionality is already present in the data 1313 model of the pNFS Block/Volume Layout (see [RFC5663]). Uninitialized 1314 blocks can thought as holes inside a space reservation window. 1316 If an application reads a hole in a sparse file, the file system must 1317 return all zeros to the application. For local data access there is 1318 little penalty, but with NFS these zeroes must be transferred back to 1319 the client. If an application uses the NFS client to read data into 1320 memory, this wastes time and bandwidth as the application waits for 1321 the zeroes to be transferred. 1323 A sparse file is typically created by initializing the file to be all 1324 zeros - nothing is written to the data in the file, instead the hole 1325 is recorded in the metadata for the file. So a 8G disk image might 1326 be represented initially by a couple hundred bits in the inode and 1327 nothing on the disk. If the VM then writes 100M to a file in the 1328 middle of the image, there would now be two holes represented in the 1329 metadata and 100M in the data. 1331 No new operation is needed to allow the creation of a sparsely 1332 populated file, when a file is created and a write occurs past the 1333 current size of the file, the non-allocated region will either be a 1334 hole or filled with zeros. The choice of behavior is dictated by the 1335 underlying file system and is transparent to the application. What 1336 is needed are the abilities to read sparse files and to punch holes 1337 to reinitialize the contents of a file. 1339 Two new operations DEALLOCATE (Section 15.4) and READ_PLUS 1340 (Section 15.10) are introduced. DEALLOCATE allows for the hole 1341 punching. I.e., an application might want to reset the allocation 1342 and reservation status of a range of the file. READ_PLUS supports 1343 all the features of READ but includes an extension to support sparse 1344 files. READ_PLUS is guaranteed to perform no worse than READ, and 1345 can dramatically improve performance with sparse files. READ_PLUS 1346 does not depend on pNFS protocol features, but can be used by pNFS to 1347 support sparse files. 1349 6.2. Terminology 1351 Regular file: An object of file type NF4REG or NF4NAMEDATTR. 1353 Sparse file: A Regular file that contains one or more holes. 1355 Hole: A byte range within a Sparse file that contains regions of all 1356 zeroes. A hole might or might not have space allocated or 1357 reserved to it. 1359 6.3. New Operations 1361 6.3.1. READ_PLUS 1363 READ_PLUS is a new variant of the NFSv4.1 READ operation [RFC5661]. 1364 Besides being able to support all of the data semantics of the READ 1365 operation, it can also be used by the client and server to 1366 efficiently transfer holes. Note that as the client has no a priori 1367 knowledge of whether a hole is present or not, if the client supports 1368 READ_PLUS and so does the server, then it should always use the 1369 READ_PLUS operation in preference to the READ operation. 1371 READ_PLUS extends the response with a new arm representing holes to 1372 avoid returning data for portions of the file which are initialized 1373 to zero and may or may not contain a backing store. Returning data 1374 blocks of uninitialized data wastes computational and network 1375 resources, thus reducing performance. 1377 When a client sends a READ operation, it is not prepared to accept a 1378 READ_PLUS-style response providing a compact encoding of the scope of 1379 holes. If a READ occurs on a sparse file, then the server must 1380 expand such data to be raw bytes. If a READ occurs in the middle of 1381 a hole, the server can only send back bytes starting from that 1382 offset. By contrast, if a READ_PLUS occurs in the middle of a hole, 1383 the server can send back a range which starts before the offset and 1384 extends past the range. 1386 6.3.2. DEALLOCATE 1388 DEALLOCATE can be used to hole punch, which allows the client to 1389 avoid the transfer of a repetitive pattern of zeros across the 1390 network. 1392 7. Space Reservation 1394 Applications want to be able to reserve space for a file, report the 1395 amount of actual disk space a file occupies, and free-up the backing 1396 space of a file when it is not required. 1398 One example is the posix_fallocate ([posix_fallocate]) which allows 1399 applications to ask for space reservations from the operating system, 1400 usually to provide a better file layout and reduce overhead for 1401 random or slow growing file appending workloads. 1403 Another example is space reservation for virtual disks in a 1404 hypervisor. In virtualized environments, virtual disk files are 1405 often stored on NFS mounted volumes. When a hypervisor creates a 1406 virtual disk file, it often tries to preallocate the space for the 1407 file so that there are no future allocation related errors during the 1408 operation of the virtual machine. Such errors prevent a virtual 1409 machine from continuing execution and result in downtime. 1411 Currently, in order to achieve such a guarantee, applications zero 1412 the entire file. The initial zeroing allocates the backing blocks 1413 and all subsequent writes are overwrites of already allocated blocks. 1414 This approach is not only inefficient in terms of the amount of I/O 1415 done, it is also not guaranteed to work on file systems that are log 1416 structured or deduplicated. An efficient way of guaranteeing space 1417 reservation would be beneficial to such applications. 1419 The new ALLOCATE operation (see Section 15.1) allows a client to 1420 request a guarantee that space will be available. The ALLOCATE 1421 operation guarantees that any future writes to the region it was 1422 successfully called for will not fail with NFS4ERR_NOSPC. 1424 Another useful feature is the ability to report the number of blocks 1425 that would be freed when a file is deleted. Currently, NFS reports 1426 two size attributes: 1428 size The logical file size of the file. 1430 space_used The size in bytes that the file occupies on disk 1432 While these attributes are sufficient for space accounting in 1433 traditional file systems, they prove to be inadequate in modern file 1434 systems that support block sharing. In such file systems, multiple 1435 inodes can point to a single block with a block reference count to 1436 guard against premature freeing. Having a way to tell the number of 1437 blocks that would be freed if the file was deleted would be useful to 1438 applications that wish to migrate files when a volume is low on 1439 space. 1441 Since virtual disks represent a hard drive in a virtual machine, a 1442 virtual disk can be viewed as a file system within a file. Since not 1443 all blocks within a file system are in use, there is an opportunity 1444 to reclaim blocks that are no longer in use. A call to deallocate 1445 blocks could result in better space efficiency. Lesser space MAY be 1446 consumed for backups after block deallocation. 1448 The following operations and attributes can be used to resolve these 1449 issues: 1451 space_freed This attribute specifies the space freed when a file is 1452 deleted, taking block sharing into consideration. 1454 DEALLOCATE This operation delallocates the blocks backing a region 1455 of the file. 1457 If space_used of a file is interpreted to mean the size in bytes of 1458 all disk blocks pointed to by the inode of the file, then shared 1459 blocks get double counted, over-reporting the space utilization. 1460 This also has the adverse effect that the deletion of a file with 1461 shared blocks frees up less than space_used bytes. 1463 On the other hand, if space_used is interpreted to mean the size in 1464 bytes of those disk blocks unique to the inode of the file, then 1465 shared blocks are not counted in any file, resulting in under- 1466 reporting of the space utilization. 1468 For example, two files A and B have 10 blocks each. Let 6 of these 1469 blocks be shared between them. Thus, the combined space utilized by 1470 the two files is 14 * BLOCK_SIZE bytes. In the former case, the 1471 combined space utilization of the two files would be reported as 20 * 1472 BLOCK_SIZE. However, deleting either would only result in 4 * 1473 BLOCK_SIZE being freed. Conversely, the latter interpretation would 1474 report that the space utilization is only 8 * BLOCK_SIZE. 1476 Adding another size attribute, space_freed (see Section 12.2.3), is 1477 helpful in solving this problem. space_freed is the number of blocks 1478 that are allocated to the given file that would be freed on its 1479 deletion. In the example, both A and B would report space_freed as 4 1480 * BLOCK_SIZE and space_used as 10 * BLOCK_SIZE. If A is deleted, B 1481 will report space_freed as 10 * BLOCK_SIZE as the deletion of B would 1482 result in the deallocation of all 10 blocks. 1484 The addition of these attributes does not solve the problem of space 1485 being over-reported. However, over-reporting is better than under- 1486 reporting. 1488 8. Application Data Block Support 1490 At the OS level, files are contained on disk blocks. Applications 1491 are also free to impose structure on the data contained in a file and 1492 we can define an Application Data Block (ADB) to be such a structure. 1493 From the application's viewpoint, it only wants to handle ADBs and 1494 not raw bytes (see [Strohm11]). An ADB is typically comprised of two 1495 sections: header and data. The header describes the characteristics 1496 of the block and can provide a means to detect corruption in the data 1497 payload. The data section is typically initialized to all zeros. 1499 The format of the header is application specific, but there are two 1500 main components typically encountered: 1502 1. An Application Data Block Number (ADBN) which allows the 1503 application to determine which data block is being referenced. 1504 This is useful when the client is not storing the blocks in 1505 contiguous memory, i.e., a logical block number. 1507 2. Fields to describe the state of the ADB and a means to detect 1508 block corruption. For both pieces of data, a useful property is 1509 that allowed values be unique in that if passed across the 1510 network, corruption due to translation between big and little 1511 endian architectures are detectable. For example, 0xF0DEDEF0 has 1512 the same bit pattern in both architectures. 1514 Applications already impose structures on files [Strohm11] and detect 1515 corruption in data blocks [Ashdown08]. What they are not able to do 1516 is efficiently transfer and store ADBs. To initialize a file with 1517 ADBs, the client must send each full ADB to the server and that must 1518 be stored on the server. 1520 In this section, we define a framework for transferring the ADB from 1521 client to server and present one approach to detecting corruption in 1522 a given ADB implementation. 1524 8.1. Generic Framework 1526 We want the representation of the ADB to be flexible enough to 1527 support many different applications. The most basic approach is no 1528 imposition of a block at all, which means we are working with the raw 1529 bytes. Such an approach would be useful for storing holes, punching 1530 holes, etc. In more complex deployments, a server might be 1531 supporting multiple applications, each with their own definition of 1532 the ADB. One might store the ADBN at the start of the block and then 1533 have a guard pattern to detect corruption [McDougall07]. The next 1534 might store the ADBN at an offset of 100 bytes within the block and 1535 have no guard pattern at all, i.e., existing applications might 1536 already have well defined formats for their data blocks. 1538 The guard pattern can be used to represent the state of the block, to 1539 protect against corruption, or both. Again, it needs to be able to 1540 be placed anywhere within the ADB. 1542 We need to be able to represent the starting offset of the block and 1543 the size of the block. Note that nothing prevents the application 1544 from defining different sized blocks in a file. 1546 8.1.1. Data Block Representation 1548 1550 struct app_data_block4 { 1551 offset4 adb_offset; 1552 length4 adb_block_size; 1553 length4 adb_block_count; 1554 length4 adb_reloff_blocknum; 1555 count4 adb_block_num; 1556 length4 adb_reloff_pattern; 1557 opaque adb_pattern<>; 1558 }; 1560 1562 The app_data_block4 structure captures the abstraction presented for 1563 the ADB. The additional fields present are to allow the transmission 1564 of adb_block_count ADBs at one time. We also use adb_block_num to 1565 convey the ADBN of the first block in the sequence. Each ADB will 1566 contain the same adb_pattern string. 1568 As both adb_block_num and adb_pattern are optional, if either 1569 adb_reloff_pattern or adb_reloff_blocknum is set to NFS4_UINT64_MAX, 1570 then the corresponding field is not set in any of the ADB. 1572 8.2. An Example of Detecting Corruption 1574 In this section, we define an ADB format in which corruption can be 1575 detected. Note that this is just one possible format and means to 1576 detect corruption. 1578 Consider a very basic implementation of an operating system's disk 1579 blocks. A block is either data or it is an indirect block which 1580 allows for files to be larger than one block. It is desired to be 1581 able to initialize a block. Lastly, to quickly unlink a file, a 1582 block can be marked invalid. The contents remain intact - which 1583 would enable this OS application to undelete a file. 1585 The application defines 4k sized data blocks, with an 8 byte block 1586 counter occurring at offset 0 in the block, and with the guard 1587 pattern occurring at offset 8 inside the block. Furthermore, the 1588 guard pattern can take one of four states: 1590 0xfeedface - This is the FREE state and indicates that the ADB 1591 format has been applied. 1593 0xcafedead - This is the DATA state and indicates that real data 1594 has been written to this block. 1596 0xe4e5c001 - This is the INDIRECT state and indicates that the 1597 block contains block counter numbers that are chained off of this 1598 block. 1600 0xba1ed4a3 - This is the INVALID state and indicates that the block 1601 contains data whose contents are garbage. 1603 Finally, it also defines an 8 byte checksum [Baira08] starting at 1604 byte 16 which applies to the remaining contents of the block. If the 1605 state is FREE, then that checksum is trivially zero. As such, the 1606 application has no need to transfer the checksum implicitly inside 1607 the ADB - it need not make the transfer layer aware of the fact that 1608 there is a checksum (see [Ashdown08] for an example of checksums used 1609 to detect corruption in application data blocks). 1611 Corruption in each ADB can thus be detected: 1613 o If the guard pattern is anything other than one of the allowed 1614 values, including all zeros. 1616 o If the guard pattern is FREE and any other byte in the remainder 1617 of the ADB is anything other than zero. 1619 o If the guard pattern is anything other than FREE, then if the 1620 stored checksum does not match the computed checksum. 1622 o If the guard pattern is INDIRECT and one of the stored indirect 1623 block numbers has a value greater than the number of ADBs in the 1624 file. 1626 o If the guard pattern is INDIRECT and one of the stored indirect 1627 block numbers is a duplicate of another stored indirect block 1628 number. 1630 As can be seen, the application can detect errors based on the 1631 combination of the guard pattern state and the checksum. But also, 1632 the application can detect corruption based on the state and the 1633 contents of the ADB. This last point is important in validating the 1634 minimum amount of data we incorporated into our generic framework. 1635 I.e., the guard pattern is sufficient in allowing applications to 1636 design their own corruption detection. 1638 Finally, it is important to note that none of these corruption checks 1639 occur in the transport layer. The server and client components are 1640 totally unaware of the file format and might report everything as 1641 being transferred correctly even in the case the application detects 1642 corruption. 1644 8.3. Example of READ_PLUS 1646 The hypothetical application presented in Section 8.2 can be used to 1647 illustrate how READ_PLUS would return an array of results. A file is 1648 created and initialized with 100 4k ADBs in the FREE state with the 1649 WRITE_SAME operation (see Section 15.12): 1651 WRITE_SAME {0, 4k, 100, 0, 0, 8, 0xfeedface} 1653 Further, assume the application writes a single ADB at 16k, changing 1654 the guard pattern to 0xcafedead, we would then have in memory: 1656 0k -> (4k - 1) : 00 00 00 00 fe ed fa ce 00 00 ... 00 00 1657 4k -> (8k - 1) : 00 00 00 01 fe ed fa ce 00 00 ... 00 00 1658 8k -> (12k - 1) : 00 00 00 02 fe ed fa ce 00 00 ... 00 00 1659 12k -> (16k - 1) : 00 00 00 03 fe ed fa ce 00 00 ... 00 00 1660 16k -> (20k - 1) : 00 00 00 04 ca fe de ad 00 00 ... 00 00 1661 20k -> (24k - 1) : 00 00 00 05 fe ed fa ce 00 00 ... 00 00 1662 24k -> (28k - 1) : 00 00 00 06 fe ed fa ce 00 00 ... 00 00 1663 ... 1664 396k -> (400k - 1) : 00 00 00 63 fe ed fa ce 00 00 ... 00 00 1666 And when the client did a READ_PLUS of 64k at the start of the file, 1667 it could get back a result of data: 1669 0k -> (4k - 1) : 00 00 00 00 fe ed fa ce 00 00 ... 00 00 1670 4k -> (8k - 1) : 00 00 00 01 fe ed fa ce 00 00 ... 00 00 1671 8k -> (12k - 1) : 00 00 00 02 fe ed fa ce 00 00 ... 00 00 1672 12k -> (16k - 1) : 00 00 00 03 fe ed fa ce 00 00 ... 00 00 1673 16k -> (20k - 1) : 00 00 00 04 ca fe de ad 00 00 ... 00 00 1674 20k -> (24k - 1) : 00 00 00 05 fe ed fa ce 00 00 ... 00 00 1675 24k -> (24k - 1) : 00 00 00 06 fe ed fa ce 00 00 ... 00 00 1676 ... 1677 62k -> (64k - 1) : 00 00 00 15 fe ed fa ce 00 00 ... 00 00 1679 8.4. An Example of Zeroing Space 1681 A simpler use case for WRITE_SAME are applications that want to 1682 efficiently zero out a file, but do not want to modify space 1683 reservations. This can easily be achieved by a call to WRITE_SAME 1684 without a ADB block numbers and pattern, e.g.: 1686 WRITE_SAME {0, 1k, 10000, 0, 0, 0, 0} 1688 9. Labeled NFS 1690 9.1. Introduction 1692 Access control models such as Unix permissions or Access Control 1693 Lists are commonly referred to as Discretionary Access Control (DAC) 1694 models. These systems base their access decisions on user identity 1695 and resource ownership. In contrast Mandatory Access Control (MAC) 1696 models base their access control decisions on the label on the 1697 subject (usually a process) and the object it wishes to access 1698 [RFC7204]. These labels may contain user identity information but 1699 usually contain additional information. In DAC systems users are 1700 free to specify the access rules for resources that they own. MAC 1701 models base their security decisions on a system wide policy 1702 established by an administrator or organization which the users do 1703 not have the ability to override. In this section, we add a MAC 1704 model to NFSv4.2. 1706 First we provide a method for transporting and storing security label 1707 data on NFSv4 file objects. Security labels have several semantics 1708 that are met by NFSv4 recommended attributes such as the ability to 1709 set the label value upon object creation. Access control on these 1710 attributes are done through a combination of two mechanisms. As with 1711 other recommended attributes on file objects the usual DAC checks 1712 (ACLs and permission bits) will be performed to ensure that proper 1713 file ownership is enforced. In addition a MAC system MAY be employed 1714 on the client, server, or both to enforce additional policy on what 1715 subjects may modify security label information. 1717 Second, we describe a method for the client to determine if an NFSv4 1718 file object security label has changed. A client which needs to know 1719 if a label on a file or set of files is going to change SHOULD 1720 request a delegation on each labeled file. In order to change such a 1721 security label, the server will have to recall delegations on any 1722 file affected by the label change, so informing clients of the label 1723 change. 1725 An additional useful feature would be modification to the RPC layer 1726 used by NFSv4 to allow RPC calls to carry security labels and enable 1727 full mode enforcement as described in Section 9.6.1. Such 1728 modifications are outside the scope of this document (see 1729 [rpcsec_gssv3]). 1731 9.2. Definitions 1733 Label Format Specifier (LFS): is an identifier used by the client to 1734 establish the syntactic format of the security label and the 1735 semantic meaning of its components. These specifiers exist in a 1736 registry associated with documents describing the format and 1737 semantics of the label. 1739 Label Format Registry: is the IANA registry (see [Quigley14]) 1740 containing all registered LFSes along with references to the 1741 documents that describe the syntactic format and semantics of the 1742 security label. 1744 Policy Identifier (PI): is an optional part of the definition of a 1745 Label Format Specifier which allows for clients and server to 1746 identify specific security policies. 1748 Object: is a passive resource within the system that we wish to be 1749 protected. Objects can be entities such as files, directories, 1750 pipes, sockets, and many other system resources relevant to the 1751 protection of the system state. 1753 Subject: is an active entity usually a process which is requesting 1754 access to an object. 1756 MAC-Aware: is a server which can transmit and store object labels. 1758 MAC-Functional: is a client or server which is Labeled NFS enabled. 1759 Such a system can interpret labels and apply policies based on the 1760 security system. 1762 Multi-Level Security (MLS): is a traditional model where objects are 1763 given a sensitivity level (Unclassified, Secret, Top Secret, etc) 1764 and a category set (see [BL73], [RFC1108], and [RFC2401]). 1766 9.3. MAC Security Attribute 1768 MAC models base access decisions on security attributes bound to 1769 subjects and objects. This information can range from a user 1770 identity for an identity based MAC model, sensitivity levels for 1771 Multi-level security, or a type for Type Enforcement. These models 1772 base their decisions on different criteria but the semantics of the 1773 security attribute remain the same. The semantics required by the 1774 security attributes are listed below: 1776 o MUST provide flexibility with respect to the MAC model. 1778 o MUST provide the ability to atomically set security information 1779 upon object creation. 1781 o MUST provide the ability to enforce access control decisions both 1782 on the client and the server. 1784 o MUST NOT expose an object to either the client or server name 1785 space before its security information has been bound to it. 1787 NFSv4 implements the security attribute as a recommended attribute. 1788 These attributes have a fixed format and semantics, which conflicts 1789 with the flexible nature of the security attribute. To resolve this 1790 the security attribute consists of two components. The first 1791 component is a LFS as defined in [Quigley14] to allow for 1792 interoperability between MAC mechanisms. The second component is an 1793 opaque field which is the actual security attribute data. To allow 1794 for various MAC models, NFSv4 should be used solely as a transport 1795 mechanism for the security attribute. It is the responsibility of 1796 the endpoints to consume the security attribute and make access 1797 decisions based on their respective models. In addition, creation of 1798 objects through OPEN and CREATE allows for the security attribute to 1799 be specified upon creation. By providing an atomic create and set 1800 operation for the security attribute it is possible to enforce the 1801 second and fourth requirements. The recommended attribute 1802 FATTR4_SEC_LABEL (see Section 12.2.2) will be used to satisfy this 1803 requirement. 1805 9.3.1. Delegations 1807 In the event that a security attribute is changed on the server while 1808 a client holds a delegation on the file, both the server and the 1809 client MUST follow the NFSv4.1 protocol (see Chapter 10 of [RFC5661]) 1810 with respect to attribute changes. It SHOULD flush all changes back 1811 to the server and relinquish the delegation. 1813 9.3.2. Permission Checking 1815 It is not feasible to enumerate all possible MAC models and even 1816 levels of protection within a subset of these models. This means 1817 that the NFSv4 client and servers cannot be expected to directly make 1818 access control decisions based on the security attribute. Instead 1819 NFSv4 should defer permission checking on this attribute to the host 1820 system. These checks are performed in addition to existing DAC and 1821 ACL checks outlined in the NFSv4 protocol. Section 9.6 gives a 1822 specific example of how the security attribute is handled under a 1823 particular MAC model. 1825 9.3.3. Object Creation 1827 When creating files in NFSv4 the OPEN and CREATE operations are used. 1828 One of the parameters to these operations is an fattr4 structure 1829 containing the attributes the file is to be created with. This 1830 allows NFSv4 to atomically set the security attribute of files upon 1831 creation. When a client is MAC-Functional it must always provide the 1832 initial security attribute upon file creation. In the event that the 1833 server is MAC-Functional as well, it should determine by policy 1834 whether it will accept the attribute from the client or instead make 1835 the determination itself. If the client is not MAC-Functional, then 1836 the MAC-Functional server must decide on a default label. A more in 1837 depth explanation can be found in Section 9.6. 1839 9.3.4. Existing Objects 1841 Note that under the MAC model, all objects must have labels. 1842 Therefore, if an existing server is upgraded to include Labeled NFS 1843 support, then it is the responsibility of the security system to 1844 define the behavior for existing objects. 1846 9.3.5. Label Changes 1848 Consider a guest mode system (Section 9.6.2) in which the clients 1849 enforce MAC checks and the server has only a DAC security system 1850 which stores the labels along with the file data. In this type of 1851 system, a user with the appropriate DAC credentials on a client with 1852 poorly configured or disabled MAC labeling enforcement is allowed 1853 access to the file label (and data) on the server and can change the 1854 label. 1856 Clients which need to know if a label on a file or set of files has 1857 changed SHOULD request a delegation on each labeled file so that a 1858 label change by another client will be known via the process 1859 described in Section 9.3.1 which must be followed: the delegation 1860 will be recalled, which effectively notifies the client of the 1861 change. 1863 Note that the MAC security policies on a client can be such that the 1864 client does not have access to the file unless it has a delegation. 1866 9.4. pNFS Considerations 1868 The new FATTR4_SEC_LABEL attribute is metadata information and as 1869 such the DS is not aware of the value contained on the MDS. 1870 Fortunately, the NFSv4.1 protocol [RFC5661] already has provisions 1871 for doing access level checks from the DS to the MDS. In order for 1872 the DS to validate the subject label presented by the client, it 1873 SHOULD utilize this mechanism. 1875 9.5. Discovery of Server Labeled NFS Support 1877 The server can easily determine that a client supports Labeled NFS 1878 when it queries for the FATTR4_SEC_LABEL label for an object. The 1879 client might need to discover which LFS the server supports. 1881 The following compound MUST NOT be denied by any MAC label check: 1883 PUTROOTFH, GETATTR {FATTR4_SEC_LABEL} 1885 Note that the server might have imposed a security flavor on the root 1886 that precludes such access. I.e., if the server requires kerberized 1887 access and the client presents a compound with AUTH_SYS, then the 1888 server is allowed to return NFS4ERR_WRONGSEC in this case. But if 1889 the client presents a correct security flavor, then the server MUST 1890 return the FATTR4_SEC_LABEL attribute with the supported LFS filled 1891 in. 1893 9.6. MAC Security NFS Modes of Operation 1895 A system using Labeled NFS may operate in two modes. The first mode 1896 provides the most protection and is called "full mode". In this mode 1897 both the client and server implement a MAC model allowing each end to 1898 make an access control decision. The remaining mode is called the 1899 "guest mode" and in this mode one end of the connection is not 1900 implementing a MAC model and thus offers less protection than full 1901 mode. 1903 9.6.1. Full Mode 1905 Full mode environments consist of MAC-Functional NFSv4 servers and 1906 clients and may be composed of mixed MAC models and policies. The 1907 system requires that both the client and server have an opportunity 1908 to perform an access control check based on all relevant information 1909 within the network. The file object security attribute is provided 1910 using the mechanism described in Section 9.3. 1912 Fully MAC-Functional NFSv4 servers are not possible in the absence of 1913 RPCSEC_GSSv3 [rpcsec_gssv3] support for subject label transport. 1914 However, servers may make decisions based on the RPC credential 1915 information available. 1917 9.6.1.1. Initial Labeling and Translation 1919 The ability to create a file is an action that a MAC model may wish 1920 to mediate. The client is given the responsibility to determine the 1921 initial security attribute to be placed on a file. This allows the 1922 client to make a decision as to the acceptable security attributes to 1923 create a file with before sending the request to the server. Once 1924 the server receives the creation request from the client it may 1925 choose to evaluate if the security attribute is acceptable. 1927 Security attributes on the client and server may vary based on MAC 1928 model and policy. To handle this the security attribute field has an 1929 LFS component. This component is a mechanism for the host to 1930 identify the format and meaning of the opaque portion of the security 1931 attribute. A full mode environment may contain hosts operating in 1932 several different LFSes. In this case a mechanism for translating 1933 the opaque portion of the security attribute is needed. The actual 1934 translation function will vary based on MAC model and policy and is 1935 out of the scope of this document. If a translation is unavailable 1936 for a given LFS then the request MUST be denied. Another recourse is 1937 to allow the host to provide a fallback mapping for unknown security 1938 attributes. 1940 9.6.1.2. Policy Enforcement 1942 In full mode access control decisions are made by both the clients 1943 and servers. When a client makes a request it takes the security 1944 attribute from the requesting process and makes an access control 1945 decision based on that attribute and the security attribute of the 1946 object it is trying to access. If the client denies that access an 1947 RPC call to the server is never made. If however the access is 1948 allowed the client will make a call to the NFS server. 1950 When the server receives the request from the client it uses any 1951 credential information conveyed in the RPC request and the attributes 1952 of the object the client is trying to access to make an access 1953 control decision. If the server's policy allows this access it will 1954 fulfill the client's request, otherwise it will return 1955 NFS4ERR_ACCESS. 1957 Future protocol extensions may also allow the server to factor into 1958 the decision a security label extracted from the RPC request. 1960 Implementations MAY validate security attributes supplied over the 1961 network to ensure that they are within a set of attributes permitted 1962 from a specific peer, and if not, reject them. Note that a system 1963 may permit a different set of attributes to be accepted from each 1964 peer. 1966 9.6.1.3. Limited Server 1968 A Limited Server mode (see Section 4.2 of [RFC7204]) consists of a 1969 server which is label aware, but does not enforce policies. Such a 1970 server will store and retrieve all object labels presented by 1971 clients, utilize the methods described in Section 9.3.5 to allow the 1972 clients to detect changing labels, but may not factor the label into 1973 access decisions. Instead, it will expect the clients to enforce all 1974 such access locally. 1976 9.6.2. Guest Mode 1978 Guest mode implies that either the client or the server does not 1979 handle labels. If the client is not Labeled NFS aware, then it will 1980 not offer subject labels to the server. The server is the only 1981 entity enforcing policy, and may selectively provide standard NFS 1982 services to clients based on their authentication credentials and/or 1983 associated network attributes (e.g., IP address, network interface). 1984 The level of trust and access extended to a client in this mode is 1985 configuration-specific. If the server is not Labeled NFS aware, then 1986 it will not return object labels to the client. Clients in this 1987 environment are may consist of groups implementing different MAC 1988 model policies. The system requires that all clients in the 1989 environment be responsible for access control checks. 1991 9.7. Security Considerations for Labeled NFS 1993 This entire chapter deals with security issues. 1995 Depending on the level of protection the MAC system offers there may 1996 be a requirement to tightly bind the security attribute to the data. 1998 When only one of the client or server enforces labels, it is 1999 important to realize that the other side is not enforcing MAC 2000 protections. Alternate methods might be in use to handle the lack of 2001 MAC support and care should be taken to identify and mitigate threats 2002 from possible tampering outside of these methods. 2004 An example of this is that a server that modifies READDIR or LOOKUP 2005 results based on the client's subject label might want to always 2006 construct the same subject label for a client which does not present 2007 one. This will prevent a non-Labeled NFS client from mixing entries 2008 in the directory cache. 2010 10. Sharing change attribute implementation details with NFSv4 clients 2012 Although both the NFSv4 [I-D.ietf-nfsv4-rfc3530bis] and NFSv4.1 2013 protocol [RFC5661], define the change attribute as being mandatory to 2014 implement, there is little in the way of guidance as to its 2015 construction. The only mandated constraint is that the value must 2016 change whenever the file data or metadata change. 2018 While this allows for a wide range of implementations, it also leaves 2019 the client with no way to determine which is the most recent value 2020 for the change attribute in a case where several RPC calls have been 2021 issued in parallel. In other words if two COMPOUNDs, both containing 2022 WRITE and GETATTR requests for the same file, have been issued in 2023 parallel, how does the client determine which of the two change 2024 attribute values returned in the replies to the GETATTR requests 2025 correspond to the most recent state of the file? In some cases, the 2026 only recourse may be to send another COMPOUND containing a third 2027 GETATTR that is fully serialized with the first two. 2029 NFSv4.2 avoids this kind of inefficiency by allowing the server to 2030 share details about how the change attribute is expected to evolve, 2031 so that the client may immediately determine which, out of the 2032 several change attribute values returned by the server, is the most 2033 recent. change_attr_type is defined as a new recommended attribute 2034 (see Section 12.2.1), and is per file system. 2036 11. Error Values 2038 NFS error numbers are assigned to failed operations within a Compound 2039 (COMPOUND or CB_COMPOUND) request. A Compound request contains a 2040 number of NFS operations that have their results encoded in sequence 2041 in a Compound reply. The results of successful operations will 2042 consist of an NFS4_OK status followed by the encoded results of the 2043 operation. If an NFS operation fails, an error status will be 2044 entered in the reply and the Compound request will be terminated. 2046 11.1. Error Definitions 2048 Protocol Error Definitions 2050 +-------------------------+--------+------------------+ 2051 | Error | Number | Description | 2052 +-------------------------+--------+------------------+ 2053 | NFS4ERR_BADLABEL | 10093 | Section 11.1.3.1 | 2054 | NFS4ERR_OFFLOAD_DENIED | 10091 | Section 11.1.2.1 | 2055 | NFS4ERR_OFFLOAD_NO_REQS | 10094 | Section 11.1.2.2 | 2056 | NFS4ERR_PARTNER_NO_AUTH | 10089 | Section 11.1.2.3 | 2057 | NFS4ERR_PARTNER_NOTSUPP | 10088 | Section 11.1.2.4 | 2058 | NFS4ERR_UNION_NOTSUPP | 10090 | Section 11.1.1.1 | 2059 | NFS4ERR_WRONG_LFS | 10092 | Section 11.1.3.2 | 2060 +-------------------------+--------+------------------+ 2062 Table 1 2064 11.1.1. General Errors 2066 This section deals with errors that are applicable to a broad set of 2067 different purposes. 2069 11.1.1.1. NFS4ERR_UNION_NOTSUPP (Error Code 10090) 2071 One of the arguments to the operation is a discriminated union and 2072 while the server supports the given operation, it does not support 2073 the selected arm of the discriminated union. 2075 11.1.2. Server to Server Copy Errors 2077 These errors deal with the interaction between server to server 2078 copies. 2080 11.1.2.1. NFS4ERR_OFFLOAD_DENIED (Error Code 10091) 2082 The copy offload operation is supported by both the source and the 2083 destination, but the destination is not allowing it for this file. 2084 If the client sees this error, it should fall back to the normal copy 2085 semantics. 2087 11.1.2.2. NFS4ERR_OFFLOAD_NO_REQS (Error Code 10094) 2089 The copy offload operation is supported by both the source and the 2090 destination, but the destination can not meet the client requirements 2091 for either consecutive byte copy or synchronous copy. If the client 2092 sees this error, it should either relax the requirements (if any) or 2093 fall back to the normal copy semantics. 2095 11.1.2.3. NFS4ERR_PARTNER_NO_AUTH (Error Code 10089) 2097 The source 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 source server, the source server 2100 receiving a server-to-server copy offload request after the copy 2101 lease time expired, or for some other permission problem. 2103 11.1.2.4. NFS4ERR_PARTNER_NOTSUPP (Error Code 10088) 2105 The remote server does not support the server-to-server copy offload 2106 protocol. 2108 11.1.3. Labeled NFS Errors 2110 These errors are used in Labeled NFS. 2112 11.1.3.1. NFS4ERR_BADLABEL (Error Code 10093) 2114 The label specified is invalid in some manner. 2116 11.1.3.2. NFS4ERR_WRONG_LFS (Error Code 10092) 2118 The LFS specified in the subject label is not compatible with the LFS 2119 in the object label. 2121 11.2. New Operations and Their Valid Errors 2123 This section contains a table that gives the valid error returns for 2124 each new NFSv4.2 protocol operation. The error code NFS4_OK 2125 (indicating no error) is not listed but should be understood to be 2126 returnable by all new operations. The error values for all other 2127 operations are defined in Section 15.2 of [RFC5661]. 2129 Valid Error Returns for Each New Protocol Operation 2131 +----------------+--------------------------------------------------+ 2132 | Operation | Errors | 2133 +----------------+--------------------------------------------------+ 2134 | ALLOCATE | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2135 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2136 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2137 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_DQUOT, | 2138 | | NFS4ERR_EXPIRED, NFS4ERR_FBIG, | 2139 | | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, | 2140 | | NFS4ERR_IO, NFS4ERR_ISDIR, NFS4ERR_MOVED, | 2141 | | NFS4ERR_NOFILEHANDLE, NFS4ERR_NOSPC, | 2142 | | NFS4ERR_NOTSUPP, NFS4ERR_OLD_STATEID, | 2143 | | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, | 2144 | | NFS4ERR_REP_TOO_BIG, | 2145 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2146 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2147 | | NFS4ERR_ROFS, NFS4ERR_SERVERFAULT, | 2148 | | NFS4ERR_STALE, NFS4ERR_SYMLINK, | 2149 | | NFS4ERR_TOO_MANY_OPS, NFS4ERR_WRONG_TYPE | 2150 | COPY | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2151 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2152 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2153 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_DQUOT, | 2154 | | NFS4ERR_EXPIRED, NFS4ERR_FBIG, | 2155 | | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, | 2156 | | NFS4ERR_IO, NFS4ERR_ISDIR, NFS4ERR_LOCKED, | 2157 | | NFS4ERR_METADATA_NOTSUPP, NFS4ERR_MOVED, | 2158 | | NFS4ERR_NOFILEHANDLE, NFS4ERR_NOSPC, | 2159 | | NFS4ERR_OFFLOAD_DENIED, NFS4ERR_OLD_STATEID, | 2160 | | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, | 2161 | | NFS4ERR_PARTNER_NO_AUTH, | 2162 | | NFS4ERR_PARTNER_NOTSUPP, NFS4ERR_PNFS_IO_HOLE, | 2163 | | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, | 2164 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2165 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2166 | | NFS4ERR_ROFS, NFS4ERR_SERVERFAULT, | 2167 | | NFS4ERR_STALE, NFS4ERR_SYMLINK, | 2168 | | NFS4ERR_TOO_MANY_OPS, NFS4ERR_WRONG_TYPE | 2169 | COPY_NOTIFY | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2170 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2171 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2172 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, | 2173 | | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, | 2174 | | NFS4ERR_ISDIR, NFS4ERR_IO, NFS4ERR_LOCKED, | 2175 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2176 | | NFS4ERR_OLD_STATEID, NFS4ERR_OPENMODE, | 2177 | | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_PNFS_IO_HOLE, | 2178 | | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, | 2179 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2180 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2181 | | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, | 2182 | | NFS4ERR_SYMLINK, NFS4ERR_TOO_MANY_OPS, | 2183 | | NFS4ERR_WRONG_TYPE | 2184 | DEALLOCATE | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2185 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2186 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2187 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, | 2188 | | NFS4ERR_FBIG, NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, | 2189 | | NFS4ERR_INVAL, NFS4ERR_IO, NFS4ERR_ISDIR, | 2190 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2191 | | NFS4ERR_NOTSUPP, NFS4ERR_OLD_STATEID, | 2192 | | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, | 2193 | | NFS4ERR_REP_TOO_BIG, | 2194 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2195 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2196 | | NFS4ERR_ROFS, NFS4ERR_SERVERFAULT, | 2197 | | NFS4ERR_STALE, NFS4ERR_SYMLINK, | 2198 | | NFS4ERR_TOO_MANY_OPS, NFS4ERR_WRONG_TYPE | 2199 | GETDEVICELIST | NFS4ERR_NOTSUPP | 2200 | LAYOUTERROR | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, | 2201 | | NFS4ERR_BAD_STATEID, NFS4ERR_DEADSESSION, | 2202 | | NFS4ERR_DELAY, NFS4ERR_DELEG_REVOKED, | 2203 | | NFS4ERR_EXPIRED, NFS4ERR_FHEXPIRED, | 2204 | | NFS4ERR_GRACE, NFS4ERR_INVAL, NFS4ERR_ISDIR, | 2205 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2206 | | NFS4ERR_NOTSUPP, NFS4ERR_NO_GRACE, | 2207 | | NFS4ERR_OLD_STATEID, NFS4ERR_OP_NOT_IN_SESSION, | 2208 | | NFS4ERR_REP_TOO_BIG, | 2209 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2210 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2211 | | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, | 2212 | | NFS4ERR_TOO_MANY_OPS, | 2213 | | NFS4ERR_UNKNOWN_LAYOUTTYPE, NFS4ERR_WRONG_CRED, | 2214 | | NFS4ERR_WRONG_TYPE | 2215 | LAYOUTSTATS | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, | 2216 | | NFS4ERR_BAD_STATEID, NFS4ERR_DEADSESSION, | 2217 | | NFS4ERR_DELAY, NFS4ERR_DELEG_REVOKED, | 2218 | | NFS4ERR_EXPIRED, NFS4ERR_FHEXPIRED, | 2219 | | NFS4ERR_GRACE, NFS4ERR_INVAL, NFS4ERR_ISDIR, | 2220 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2221 | | NFS4ERR_NOTSUPP, NFS4ERR_NO_GRACE, | 2222 | | NFS4ERR_OLD_STATEID, NFS4ERR_OP_NOT_IN_SESSION, | 2223 | | NFS4ERR_REP_TOO_BIG, | 2224 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2225 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2226 | | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, | 2227 | | NFS4ERR_TOO_MANY_OPS, | 2228 | | NFS4ERR_UNKNOWN_LAYOUTTYPE, NFS4ERR_WRONG_CRED, | 2229 | | NFS4ERR_WRONG_TYPE | 2230 | OFFLOAD_CANCEL | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, | 2231 | | NFS4ERR_BAD_STATEID, NFS4ERR_COMPLETE_ALREADY, | 2232 | | NFS4ERR_DEADSESSION, NFS4ERR_EXPIRED, | 2233 | | NFS4ERR_DELAY, NFS4ERR_GRACE, NFS4ERR_NOTSUPP, | 2234 | | NFS4ERR_OLD_STATEID, NFS4ERR_OP_NOT_IN_SESSION, | 2235 | | NFS4ERR_SERVERFAULT, NFS4ERR_TOO_MANY_OPS | 2236 | OFFLOAD_STATUS | NFS4ERR_ADMIN_REVOKED, NFS4ERR_BADXDR, | 2237 | | NFS4ERR_BAD_STATEID, NFS4ERR_COMPLETE_ALREADY, | 2238 | | NFS4ERR_DEADSESSION, NFS4ERR_EXPIRED, | 2239 | | NFS4ERR_DELAY, NFS4ERR_GRACE, NFS4ERR_NOTSUPP, | 2240 | | NFS4ERR_OLD_STATEID, NFS4ERR_OP_NOT_IN_SESSION, | 2241 | | NFS4ERR_SERVERFAULT, NFS4ERR_TOO_MANY_OPS | 2242 | READ_PLUS | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2243 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2244 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2245 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, | 2246 | | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, | 2247 | | NFS4ERR_ISDIR, NFS4ERR_IO, NFS4ERR_LOCKED, | 2248 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2249 | | NFS4ERR_NOTSUPP, NFS4ERR_OLD_STATEID, | 2250 | | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, | 2251 | | NFS4ERR_PNFS_IO_HOLE, NFS4ERR_PNFS_NO_LAYOUT, | 2252 | | NFS4ERR_REP_TOO_BIG, | 2253 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2254 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2255 | | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, | 2256 | | NFS4ERR_SYMLINK, NFS4ERR_TOO_MANY_OPS, | 2257 | | NFS4ERR_WRONG_TYPE | 2258 | SEEK | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2259 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2260 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2261 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_EXPIRED, | 2262 | | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, | 2263 | | NFS4ERR_ISDIR, NFS4ERR_IO, NFS4ERR_LOCKED, | 2264 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2265 | | NFS4ERR_NOTSUPP, NFS4ERR_OLD_STATEID, | 2266 | | NFS4ERR_OPENMODE, NFS4ERR_OP_NOT_IN_SESSION, | 2267 | | NFS4ERR_PNFS_IO_HOLE, NFS4ERR_PNFS_NO_LAYOUT, | 2268 | | NFS4ERR_REP_TOO_BIG, | 2269 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2270 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2271 | | NFS4ERR_SERVERFAULT, NFS4ERR_STALE, | 2272 | | NFS4ERR_SYMLINK, NFS4ERR_TOO_MANY_OPS, | 2273 | | NFS4ERR_UNION_NOTSUPP, NFS4ERR_WRONG_TYPE | 2274 | WRITE_SAME | NFS4ERR_ACCESS, NFS4ERR_ADMIN_REVOKED, | 2275 | | NFS4ERR_BADXDR, NFS4ERR_BAD_STATEID, | 2276 | | NFS4ERR_DEADSESSION, NFS4ERR_DELAY, | 2277 | | NFS4ERR_DELEG_REVOKED, NFS4ERR_DQUOT, | 2278 | | NFS4ERR_EXPIRED, NFS4ERR_FBIG, | 2279 | | NFS4ERR_FHEXPIRED, NFS4ERR_GRACE, NFS4ERR_INVAL, | 2280 | | NFS4ERR_IO, NFS4ERR_ISDIR, NFS4ERR_LOCKED, | 2281 | | NFS4ERR_MOVED, NFS4ERR_NOFILEHANDLE, | 2282 | | NFS4ERR_NOSPC, NFS4ERR_NOTSUPP, | 2283 | | NFS4ERR_OLD_STATEID, NFS4ERR_OPENMODE, | 2284 | | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_PNFS_IO_HOLE, | 2285 | | NFS4ERR_PNFS_NO_LAYOUT, NFS4ERR_REP_TOO_BIG, | 2286 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, | 2287 | | NFS4ERR_REQ_TOO_BIG, NFS4ERR_RETRY_UNCACHED_REP, | 2288 | | NFS4ERR_ROFS, NFS4ERR_SERVERFAULT, | 2289 | | NFS4ERR_STALE, NFS4ERR_SYMLINK, | 2290 | | NFS4ERR_TOO_MANY_OPS, NFS4ERR_WRONG_TYPE | 2291 +----------------+--------------------------------------------------+ 2293 Table 2 2295 11.3. New Callback Operations and Their Valid Errors 2297 This section contains a table that gives the valid error returns for 2298 each new NFSv4.2 callback operation. The error code NFS4_OK 2299 (indicating no error) is not listed but should be understood to be 2300 returnable by all new callback operations. The error values for all 2301 other callback operations are defined in Section 15.3 of [RFC5661]. 2303 Valid Error Returns for Each New Protocol Callback Operation 2305 +------------+------------------------------------------------------+ 2306 | Callback | Errors | 2307 | Operation | | 2308 +------------+------------------------------------------------------+ 2309 | CB_OFFLOAD | NFS4ERR_BADHANDLE, NFS4ERR_BADXDR, | 2310 | | NFS4ERR_BAD_STATEID, NFS4ERR_DELAY, | 2311 | | NFS4ERR_OP_NOT_IN_SESSION, NFS4ERR_REP_TOO_BIG, | 2312 | | NFS4ERR_REP_TOO_BIG_TO_CACHE, NFS4ERR_REQ_TOO_BIG, | 2313 | | NFS4ERR_RETRY_UNCACHED_REP, NFS4ERR_SERVERFAULT, | 2314 | | NFS4ERR_TOO_MANY_OPS | 2315 +------------+------------------------------------------------------+ 2317 Table 3 2319 12. New File Attributes 2321 12.1. New RECOMMENDED Attributes - List and Definition References 2323 The list of new RECOMMENDED attributes appears in Table 4. The 2324 meaning of the columns of the table are: 2326 Name: The name of the attribute. 2328 Id: The number assigned to the attribute. In the event of conflicts 2329 between the assigned number and [NFSv42xdr], the latter is likely 2330 authoritative, but should be resolved with Errata to this document 2331 and/or [NFSv42xdr]. See [IESG08] for the Errata process. 2333 Data Type: The XDR data type of the attribute. 2335 Acc: Access allowed to the attribute. 2337 R means read-only (GETATTR may retrieve, SETATTR may not set). 2339 W means write-only (SETATTR may set, GETATTR may not retrieve). 2341 R W means read/write (GETATTR may retrieve, SETATTR may set). 2343 Defined in: The section of this specification that describes the 2344 attribute. 2346 +------------------+----+-------------------+-----+----------------+ 2347 | Name | Id | Data Type | Acc | Defined in | 2348 +------------------+----+-------------------+-----+----------------+ 2349 | space_freed | 77 | length4 | R | Section 12.2.3 | 2350 | change_attr_type | 78 | change_attr_type4 | R | Section 12.2.1 | 2351 | sec_label | 79 | sec_label4 | R W | Section 12.2.2 | 2352 +------------------+----+-------------------+-----+----------------+ 2354 Table 4 2356 12.2. Attribute Definitions 2358 12.2.1. Attribute 78: change_attr_type 2360 2361 enum change_attr_type4 { 2362 NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR = 0, 2363 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER = 1, 2364 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS = 2, 2365 NFS4_CHANGE_TYPE_IS_TIME_METADATA = 3, 2366 NFS4_CHANGE_TYPE_IS_UNDEFINED = 4 2367 }; 2369 2371 change_attr_type is a per file system attribute which enables the 2372 NFSv4.2 server to provide additional information about how it expects 2373 the change attribute value to evolve after the file data, or metadata 2374 has changed. While Section 5.4 of [RFC5661] discusses per file 2375 system attributes, it is expected that the value of change_attr_type 2376 not depend on the value of "homogeneous" and only changes in the 2377 event of a migration. 2379 NFS4_CHANGE_TYPE_IS_UNDEFINED: The change attribute does not take 2380 values that fit into any of these categories. 2382 NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR: The change attribute value MUST 2383 monotonically increase for every atomic change to the file 2384 attributes, data, or directory contents. 2386 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER: The change attribute value MUST 2387 be incremented by one unit for every atomic change to the file 2388 attributes, data, or directory contents. This property is 2389 preserved when writing to pNFS data servers. 2391 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS: The change attribute 2392 value MUST be incremented by one unit for every atomic change to 2393 the file attributes, data, or directory contents. In the case 2394 where the client is writing to pNFS data servers, the number of 2395 increments is not guaranteed to exactly match the number of 2396 writes. 2398 NFS4_CHANGE_TYPE_IS_TIME_METADATA: The change attribute is 2399 implemented as suggested in [I-D.ietf-nfsv4-rfc3530bis] in terms 2400 of the time_metadata attribute. 2402 If either NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR, 2403 NFS4_CHANGE_TYPE_IS_VERSION_COUNTER, or 2404 NFS4_CHANGE_TYPE_IS_TIME_METADATA are set, then the client knows at 2405 the very least that the change attribute is monotonically increasing, 2406 which is sufficient to resolve the question of which value is the 2407 most recent. 2409 If the client sees the value NFS4_CHANGE_TYPE_IS_TIME_METADATA, then 2410 by inspecting the value of the 'time_delta' attribute it additionally 2411 has the option of detecting rogue server implementations that use 2412 time_metadata in violation of the spec. 2414 If the client sees NFS4_CHANGE_TYPE_IS_VERSION_COUNTER, it has the 2415 ability to predict what the resulting change attribute value should 2416 be after a COMPOUND containing a SETATTR, WRITE, or CREATE. This 2417 again allows it to detect changes made in parallel by another client. 2418 The value NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS permits the 2419 same, but only if the client is not doing pNFS WRITEs. 2421 Finally, if the server does not support change_attr_type or if 2422 NFS4_CHANGE_TYPE_IS_UNDEFINED is set, then the server SHOULD make an 2423 effort to implement the change attribute in terms of the 2424 time_metadata attribute. 2426 12.2.2. Attribute 79: sec_label 2428 2430 typedef uint32_t policy4; 2432 struct labelformat_spec4 { 2433 policy4 lfs_lfs; 2434 policy4 lfs_pi; 2435 }; 2437 struct sec_label4 { 2438 labelformat_spec4 slai_lfs; 2439 opaque slai_data<>; 2440 }; 2442 2444 The FATTR4_SEC_LABEL contains an array of two components with the 2445 first component being an LFS. It serves to provide the receiving end 2446 with the information necessary to translate the security attribute 2447 into a form that is usable by the endpoint. Label Formats assigned 2448 an LFS may optionally choose to include a Policy Identifier field to 2449 allow for complex policy deployments. The LFS and Label Format 2450 Registry are described in detail in [Quigley14]. The translation 2451 used to interpret the security attribute is not specified as part of 2452 the protocol as it may depend on various factors. The second 2453 component is an opaque section which contains the data of the 2454 attribute. This component is dependent on the MAC model to interpret 2455 and enforce. 2457 In particular, it is the responsibility of the LFS specification to 2458 define a maximum size for the opaque section, slai_data<>. When 2459 creating or modifying a label for an object, the client needs to be 2460 guaranteed that the server will accept a label that is sized 2461 correctly. By both client and server being part of a specific MAC 2462 model, the client will be aware of the size. 2464 12.2.3. Attribute 77: space_freed 2466 space_freed gives the number of bytes freed if the file is deleted. 2467 This attribute is read only and is of type length4. It is a per file 2468 attribute. 2470 13. Operations: REQUIRED, RECOMMENDED, or OPTIONAL 2472 The following tables summarize the operations of the NFSv4.2 protocol 2473 and the corresponding designation of REQUIRED, RECOMMENDED, and 2474 OPTIONAL to implement or MUST NOT implement. The designation of MUST 2475 NOT implement is reserved for those operations that were defined in 2476 either NFSv4.0 or NFSV4.1 and MUST NOT be implemented in NFSv4.2. 2478 For the most part, the REQUIRED, RECOMMENDED, or OPTIONAL designation 2479 for operations sent by the client is for the server implementation. 2480 The client is generally required to implement the operations needed 2481 for the operating environment for which it serves. For example, a 2482 read-only NFSv4.2 client would have no need to implement the WRITE 2483 operation and is not required to do so. 2485 The REQUIRED or OPTIONAL designation for callback operations sent by 2486 the server is for both the client and server. Generally, the client 2487 has the option of creating the backchannel and sending the operations 2488 on the fore channel that will be a catalyst for the server sending 2489 callback operations. A partial exception is CB_RECALL_SLOT; the only 2490 way the client can avoid supporting this operation is by not creating 2491 a backchannel. 2493 Since this is a summary of the operations and their designation, 2494 there are subtleties that are not presented here. Therefore, if 2495 there is a question of the requirements of implementation, the 2496 operation descriptions themselves must be consulted along with other 2497 relevant explanatory text within this either specification or that of 2498 NFSv4.1 [RFC5661]. 2500 The abbreviations used in the second and third columns of the table 2501 are defined as follows. 2503 REQ: REQUIRED to implement 2504 REC: RECOMMENDED to implement 2506 OPT: OPTIONAL to implement 2508 MNI: MUST NOT implement 2510 For the NFSv4.2 features that are OPTIONAL, the operations that 2511 support those features are OPTIONAL, and the server MUST return 2512 NFS4ERR_NOTSUPP in response to the client's use of those operations, 2513 when those operations are not implemented by the server. If an 2514 OPTIONAL feature is supported, it is possible that a set of 2515 operations related to the feature become REQUIRED to implement. The 2516 third column of the table designates the feature(s) and if the 2517 operation is REQUIRED or OPTIONAL in the presence of support for the 2518 feature. 2520 The OPTIONAL features identified and their abbreviations are as 2521 follows: 2523 pNFS: Parallel NFS 2525 FDELG: File Delegations 2527 DDELG: Directory Delegations 2529 COPYra: Intra-server Server Side Copy 2531 COPYer: Inter-server Server Side Copy 2533 ADB: Application Data Blocks 2535 Operations 2537 +----------------------+---------------------+----------------------+ 2538 | Operation | EOL, REQ, REC, OPT, | Feature (REQ, REC, | 2539 | | or MNI | or OPT) | 2540 +----------------------+---------------------+----------------------+ 2541 | ALLOCATE | OPT | | 2542 | ACCESS | REQ | | 2543 | BACKCHANNEL_CTL | REQ | | 2544 | BIND_CONN_TO_SESSION | REQ | | 2545 | CLOSE | REQ | | 2546 | COMMIT | REQ | | 2547 | COPY | OPT | COPYer (REQ), COPYra | 2548 | | | (REQ) | 2549 | COPY_NOTIFY | OPT | COPYer (REQ) | 2550 | DEALLOCATE | OPT | | 2551 | CREATE | REQ | | 2552 | CREATE_SESSION | REQ | | 2553 | DELEGPURGE | OPT | FDELG (REQ) | 2554 | DELEGRETURN | OPT | FDELG, DDELG, pNFS | 2555 | | | (REQ) | 2556 | DESTROY_CLIENTID | REQ | | 2557 | DESTROY_SESSION | REQ | | 2558 | EXCHANGE_ID | REQ | | 2559 | FREE_STATEID | REQ | | 2560 | GETATTR | REQ | | 2561 | GETDEVICEINFO | OPT | pNFS (REQ) | 2562 | GETDEVICELIST | MNI | pNFS (MNI) | 2563 | GETFH | REQ | | 2564 | GET_DIR_DELEGATION | OPT | DDELG (REQ) | 2565 | LAYOUTCOMMIT | OPT | pNFS (REQ) | 2566 | LAYOUTGET | OPT | pNFS (REQ) | 2567 | LAYOUTRETURN | OPT | pNFS (REQ) | 2568 | LAYOUTERROR | OPT | pNFS (OPT) | 2569 | LAYOUTSTATS | OPT | pNFS (OPT) | 2570 | LINK | OPT | | 2571 | LOCK | REQ | | 2572 | LOCKT | REQ | | 2573 | LOCKU | REQ | | 2574 | LOOKUP | REQ | | 2575 | LOOKUPP | REQ | | 2576 | NVERIFY | REQ | | 2577 | OFFLOAD_CANCEL | OPT | COPYer (REQ), COPYra | 2578 | | | (REQ) | 2579 | OFFLOAD_STATUS | OPT | COPYer (REQ), COPYra | 2580 | | | (REQ) | 2581 | OPEN | REQ | | 2582 | OPENATTR | OPT | | 2583 | OPEN_CONFIRM | MNI | | 2584 | OPEN_DOWNGRADE | REQ | | 2585 | PUTFH | REQ | | 2586 | PUTPUBFH | REQ | | 2587 | PUTROOTFH | REQ | | 2588 | READ | REQ | | 2589 | READDIR | REQ | | 2590 | READLINK | OPT | | 2591 | READ_PLUS | OPT | | 2592 | RECLAIM_COMPLETE | REQ | | 2593 | RELEASE_LOCKOWNER | MNI | | 2594 | REMOVE | REQ | | 2595 | RENAME | REQ | | 2596 | RENEW | MNI | | 2597 | RESTOREFH | REQ | | 2598 | SAVEFH | REQ | | 2599 | SECINFO | REQ | | 2600 | SECINFO_NO_NAME | REC | pNFS file layout | 2601 | | | (REQ) | 2602 | SEEK | OPT | | 2603 | SEQUENCE | REQ | | 2604 | SETATTR | REQ | | 2605 | SETCLIENTID | MNI | | 2606 | SETCLIENTID_CONFIRM | MNI | | 2607 | SET_SSV | REQ | | 2608 | TEST_STATEID | REQ | | 2609 | VERIFY | REQ | | 2610 | WANT_DELEGATION | OPT | FDELG (OPT) | 2611 | WRITE | REQ | | 2612 | WRITE_SAME | OPT | ADB (REQ) | 2613 +----------------------+---------------------+----------------------+ 2615 Callback Operations 2617 +-------------------------+------------------+----------------------+ 2618 | Operation | REQ, REC, OPT, | Feature (REQ, REC, | 2619 | | or MNI | or OPT) | 2620 +-------------------------+------------------+----------------------+ 2621 | CB_OFFLOAD | OPT | COPYer (REQ), COPYra | 2622 | | | (REQ) | 2623 | CB_GETATTR | OPT | FDELG (REQ) | 2624 | CB_LAYOUTRECALL | OPT | pNFS (REQ) | 2625 | CB_NOTIFY | OPT | DDELG (REQ) | 2626 | CB_NOTIFY_DEVICEID | OPT | pNFS (OPT) | 2627 | CB_NOTIFY_LOCK | OPT | | 2628 | CB_PUSH_DELEG | OPT | FDELG (OPT) | 2629 | CB_RECALL | OPT | FDELG, DDELG, pNFS | 2630 | | | (REQ) | 2631 | CB_RECALL_ANY | OPT | FDELG, DDELG, pNFS | 2632 | | | (REQ) | 2633 | CB_RECALL_SLOT | REQ | | 2634 | CB_RECALLABLE_OBJ_AVAIL | OPT | DDELG, pNFS (REQ) | 2635 | CB_SEQUENCE | OPT | FDELG, DDELG, pNFS | 2636 | | | (REQ) | 2637 | CB_WANTS_CANCELLED | OPT | FDELG, DDELG, pNFS | 2638 | | | (REQ) | 2639 +-------------------------+------------------+----------------------+ 2641 14. Modifications to NFSv4.1 Operations 2643 14.1. Operation 42: EXCHANGE_ID - Instantiate Client ID 2644 14.1.1. ARGUMENT 2646 2648 /* new */ 2649 const EXCHGID4_FLAG_SUPP_FENCE_OPS = 0x00000004; 2651 2653 14.1.2. RESULT 2655 Unchanged 2657 14.1.3. MOTIVATION 2659 Enterprise applications require guarantees that an operation has 2660 either aborted or completed. NFSv4.1 provides this guarantee as long 2661 as the session is alive: simply send a SEQUENCE operation on the same 2662 slot with a new sequence number, and the successful return of 2663 SEQUENCE indicates the previous operation has completed. However, if 2664 the session is lost, there is no way to know when any in progress 2665 operations have aborted or completed. In hindsight, the NFSv4.1 2666 specification should have mandated that DESTROY_SESSION either abort 2667 or complete all outstanding operations. 2669 14.1.4. DESCRIPTION 2671 A client SHOULD request the EXCHGID4_FLAG_SUPP_FENCE_OPS capability 2672 when it sends an EXCHANGE_ID operation. The server SHOULD set this 2673 capability in the EXCHANGE_ID reply whether the client requests it or 2674 not. It is the server's return that determines whether this 2675 capability is in effect. When it is in effect, the following will 2676 occur: 2678 o The server will not reply to any DESTROY_SESSION invoked with the 2679 client ID until all operations in progress are completed or 2680 aborted. 2682 o The server will not reply to subsequent EXCHANGE_ID invoked on the 2683 same client owner with a new verifier until all operations in 2684 progress on the client ID's session are completed or aborted. 2686 o In implementations where the NFS server is deployed as a cluster, 2687 it does support client ID trunking, and the 2688 EXCHGID4_FLAG_SUPP_FENCE_OPS capability is enabled, then a session 2689 ID created on one node of the storage cluster MUST be destroyable 2690 via DESTROY_SESSION. In addition, DESTROY_CLIENTID and an 2691 EXCHANGE_ID with a new verifier affects all sessions regardless 2692 what node the sessions were created on. 2694 14.2. Operation 48: GETDEVICELIST - Get All Device Mappings for a File 2695 System 2697 14.2.1. ARGUMENT 2699 2701 struct GETDEVICELIST4args { 2702 /* CURRENT_FH: object belonging to the file system */ 2703 layouttype4 gdla_layout_type; 2705 /* number of deviceIDs to return */ 2706 count4 gdla_maxdevices; 2708 nfs_cookie4 gdla_cookie; 2709 verifier4 gdla_cookieverf; 2710 }; 2712 2714 14.2.2. RESULT 2716 2718 struct GETDEVICELIST4resok { 2719 nfs_cookie4 gdlr_cookie; 2720 verifier4 gdlr_cookieverf; 2721 deviceid4 gdlr_deviceid_list<>; 2722 bool gdlr_eof; 2723 }; 2725 union GETDEVICELIST4res switch (nfsstat4 gdlr_status) { 2726 case NFS4_OK: 2727 GETDEVICELIST4resok gdlr_resok4; 2728 default: 2729 void; 2730 }; 2732 2734 14.2.3. MOTIVATION 2736 The GETDEVICELIST operation was introduced in [RFC5661] specifically 2737 to request a list of devices at filesystem mount time from block 2738 layout type servers. However use of the GETDEVICELIST operation 2739 introduces a race condition versus notification about changes to pNFS 2740 device IDs as provided by CB_NOTIFY_DEVICEID. Implementation 2741 experience with block layout servers has shown there is no need for 2742 GETDEVICELIST. Clients have to be able to request new devices using 2743 GETDEVICEINFO at any time in response either to a new deviceid in 2744 LAYOUTGET results or to the CB_NOTIFY_DEVICEID callback operation. 2746 14.2.4. DESCRIPTION 2748 Clients and servers MUST NOT implement the GETDEVICELIST operation. 2750 15. NFSv4.2 Operations 2752 15.1. Operation 59: ALLOCATE - Reserve Space in A Region of a File 2754 15.1.1. ARGUMENT 2756 2758 struct ALLOCATE4args { 2759 /* CURRENT_FH: file */ 2760 stateid4 aa_stateid; 2761 offset4 aa_offset; 2762 length4 aa_length; 2763 }; 2765 2767 15.1.2. RESULT 2769 2771 struct ALLOCATE4res { 2772 nfsstat4 ar_status; 2773 }; 2775 2777 15.1.3. DESCRIPTION 2779 Whenever a client wishes to reserve space for a region in a file it 2780 calls the ALLOCATE operation with the current filehandle set to the 2781 filehandle of the file in question, and the start offset and length 2782 in bytes of the region set in aa_offset and aa_length respectively. 2784 The server will ensure that backing blocks are reserved to the region 2785 specified by aa_offset and aa_length, and that no future writes into 2786 this region will return NFS4ERR_NOSPC. If the region lies partially 2787 or fully outside the current file size the file size will be set to 2788 aa_offset + aa_length implicitly. If the server cannot guarantee 2789 this, it must return NFS4ERR_NOSPC. 2791 The ALLOCATE operation can also be used to extend the size of a file 2792 if the region specified by aa_offset and aa_length extends beyond the 2793 current file size. In that case any data outside of the previous 2794 file size will return zeroes when read before data is written to it. 2796 It is not required that the server allocate the space to the file 2797 before returning success. The allocation can be deferred, however, 2798 it must be guaranteed that it will not fail for lack of space. The 2799 deferral does not result in an asynchronous reply. 2801 The ALLOCATE operation will result in the space_used attribute and 2802 space_freed attributes being increased by the number of bytes 2803 reserved unless they were previously reserved or written and not 2804 shared. 2806 15.2. Operation 60: COPY - Initiate a server-side copy 2808 15.2.1. ARGUMENT 2810 2812 struct COPY4args { 2813 /* SAVED_FH: source file */ 2814 /* CURRENT_FH: destination file */ 2815 stateid4 ca_src_stateid; 2816 stateid4 ca_dst_stateid; 2817 offset4 ca_src_offset; 2818 offset4 ca_dst_offset; 2819 length4 ca_count; 2820 bool ca_consecutive; 2821 bool ca_synchronous; 2822 netloc4 ca_source_server<>; 2823 }; 2825 2827 15.2.2. RESULT 2829 2831 struct write_response4 { 2832 stateid4 wr_callback_id<1>; 2833 length4 wr_count; 2834 stable_how4 wr_committed; 2835 verifier4 wr_writeverf; 2836 }; 2838 struct COPY4res { 2839 nfsstat4 cr_status; 2840 write_response4 cr_response; 2841 bool cr_consecutive; 2842 bool cr_synchronous; 2843 }; 2845 2847 15.2.3. DESCRIPTION 2849 The COPY operation is used for both intra-server and inter-server 2850 copies. In both cases, the COPY is always sent from the client to 2851 the destination server of the file copy. The COPY operation requests 2852 that a file be copied from the location specified by the SAVED_FH 2853 value to the location specified by the CURRENT_FH. 2855 The SAVED_FH must be a regular file. If SAVED_FH is not a regular 2856 file, the operation MUST fail and return NFS4ERR_WRONG_TYPE. 2858 In order to set SAVED_FH to the source file handle, the compound 2859 procedure requesting the COPY will include a sub-sequence of 2860 operations such as 2862 PUTFH source-fh 2863 SAVEFH 2865 If the request is for an inter-server-to-server copy, the source-fh 2866 is a filehandle from the source server and the compound procedure is 2867 being executed on the destination server. In this case, the source- 2868 fh is a foreign filehandle on the server receiving the COPY request. 2869 If either PUTFH or SAVEFH checked the validity of the filehandle, the 2870 operation would likely fail and return NFS4ERR_STALE. 2872 If a server supports the inter-server-to-server COPY feature, a PUTFH 2873 followed by a SAVEFH MUST NOT return NFS4ERR_STALE for either 2874 operation. These restrictions do not pose substantial difficulties 2875 for servers. The CURRENT_FH and SAVED_FH may be validated in the 2876 context of the operation referencing them and an NFS4ERR_STALE error 2877 returned for an invalid file handle at that point. 2879 For an inter-server copy, the ca_dst_stateid MUST refer to either 2880 delegation, locking, or open states provided earlier by the server 2881 (see Section 4.4.1). The order of selection is explained in 2882 Section 8.2.5 of [RFC5661]. And the ca_src_stateid MUST be the 2883 cnr_stateid returned from the earlier COPY_NOTIFY. If either stateid 2884 is invalid, then the operation MUST fail. If the request is for an 2885 intra-server copy, then the ca_src_stateid can be ignored. If 2886 ca_dst_stateid is invalid, then the operation MUST fail. 2888 The CURRENT_FH specifies the destination of the copy operation. The 2889 CURRENT_FH MUST be a regular file and not a directory. Note, the 2890 file MUST exist before the COPY operation begins. It is the 2891 responsibility of the client to create the file if necessary, 2892 regardless of the actual copy protocol used. If the file cannot be 2893 created in the destination file system (due to file name 2894 restrictions, such as case or length), the COPY operation MUST NOT be 2895 called. 2897 The ca_src_offset is the offset within the source file from which the 2898 data will be read, the ca_dst_offset is the offset within the 2899 destination file to which the data will be written, and the ca_count 2900 is the number of bytes that will be copied. An offset of 0 (zero) 2901 specifies the start of the file. A count of 0 (zero) requests that 2902 all bytes from ca_src_offset through EOF be copied to the 2903 destination. If concurrent modifications to the source file overlap 2904 with the source file region being copied, the data copied may include 2905 all, some, or none of the modifications. The client can use standard 2906 NFS operations (e.g., OPEN with OPEN4_SHARE_DENY_WRITE or mandatory 2907 byte range locks) to protect against concurrent modifications if the 2908 client is concerned about this. If the source file's end of file is 2909 being modified in parallel with a copy that specifies a count of 0 2910 (zero) bytes, the amount of data copied is implementation dependent 2911 (clients may guard against this case by specifying a non-zero count 2912 value or preventing modification of the source file as mentioned 2913 above). 2915 If the source offset or the source offset plus count is greater than 2916 or equal to the size of the source file, the operation will fail with 2917 NFS4ERR_INVAL. The destination offset or destination offset plus 2918 count may be greater than the size of the destination file. This 2919 allows for the client to issue parallel copies to implement 2920 operations such as 2922 2924 % cat file1 file2 file3 file4 > dest 2926 2928 If the ca_source_server list is specified, then this is an inter- 2929 server copy operation and the source file is on a remote server. The 2930 client is expected to have previously issued a successful COPY_NOTIFY 2931 request to the remote source server. The ca_source_server list MUST 2932 be the same as the COPY_NOTIFY response's cnr_source_server list. If 2933 the client includes the entries from the COPY_NOTIFY response's 2934 cnr_source_server list in the ca_source_server list, the source 2935 server can indicate a specific copy protocol for the destination 2936 server to use by returning a URL, which specifies both a protocol 2937 service and server name. Server-to-server copy protocol 2938 considerations are described in Section 4.7 and Section 4.10.1. 2940 If ca_consecutive is set, then the client has specified that the copy 2941 protocol selected MUST copy bytes in consecutive order from 2942 ca_src_offset to ca_count. If the destination server cannot meet 2943 this requirement, then it MUST return an error of 2944 NFS4ERR_OFFLOAD_NO_REQS and set cr_consecutive to be false. 2945 Likewise, if ca_synchronous is set, then the client has required that 2946 the copy protocol selected MUST perform a synchronous copy. If the 2947 destination server cannot meet this requirement, then it MUST return 2948 an error of NFS4ERR_OFFLOAD_NO_REQS and set cr_synchronous to be 2949 false. 2951 If both are set by the client, then the destination SHOULD try to 2952 determine if it can respond to both requirements at the same time. 2953 If it cannot make that determination, it must set to false the one it 2954 can and set to true the other. The client, upon getting an 2955 NFS4ERR_OFFLOAD_NO_REQS error, has to examine both cr_consecutive and 2956 cr_synchronous against the respective values of ca_consecutive and 2957 ca_synchronous to determine the possible requirement not met. It 2958 MUST be prepared for the destination server not being able to 2959 determine both requirements at the same time. 2961 Upon receiving the NFS4ERR_OFFLOAD_NO_REQS error, the client has to 2962 determine if it wants to either re-request the copy with a relaxed 2963 set of requirements or if it wants to revert to manually copying the 2964 data. If it decides to manually copy the data and this is a remote 2965 copy, then the client is responsible for informing the source that 2966 the earlier COPY_NOTIFY is no longer valid by sending it an 2967 OFFLOAD_CANCEL. 2969 The copying of any and all attributes on the source file is the 2970 responsibility of both the client and the copy protocol. Any 2971 attribute which is both exposed via the NFS protocol on the source 2972 file and set SHOULD be copied to the destination file. Any attribute 2973 supported by the destination server that is not set on the source 2974 file SHOULD be left unset. If the client cannot copy an attribute 2975 from the source to destination, it MAY fail the copy transaction. 2977 Metadata attributes not exposed via the NFS protocol SHOULD be copied 2978 to the destination file where appropriate via the copy protocol. 2979 Note that if the copy protocol is NFSv4.x, then these attributes will 2980 be lost. 2982 The destination file's named attributes are not duplicated from the 2983 source file. After the copy process completes, the client MAY 2984 attempt to duplicate named attributes using standard NFSv4 2985 operations. However, the destination file's named attribute 2986 capabilities MAY be different from the source file's named attribute 2987 capabilities. 2989 If the operation does not result in an immediate failure, the server 2990 will return NFS4_OK, and the CURRENT_FH will remain the destination's 2991 filehandle. 2993 If the wr_callback_id is returned, this indicates that the operation 2994 was initiated and a CB_OFFLOAD callback will deliver the final 2995 results of the operation. The wr_callback_id stateid is termed a 2996 copy stateid in this context. The server is given the option of 2997 returning the results in a callback because the data may require a 2998 relatively long period of time to copy. 3000 If no wr_callback_id is returned, the operation completed 3001 synchronously and no callback will be issued by the server. The 3002 completion status of the operation is indicated by cr_status. 3004 If the copy completes successfully, either synchronously or 3005 asynchronously, the data copied from the source file to the 3006 destination file MUST appear identical to the NFS client. However, 3007 the NFS server's on disk representation of the data in the source 3008 file and destination file MAY differ. For example, the NFS server 3009 might encrypt, compress, deduplicate, or otherwise represent the on 3010 disk data in the source and destination file differently. 3012 If a failure does occur for a synchronous copy, wr_count will be set 3013 to the number of bytes copied to the destination file before the 3014 error occurred. If cr_consecutive is true, then the bytes were 3015 copied in order. If the failure occurred for an asynchronous copy, 3016 then the client will have gotten the notification of the consecutive 3017 copy order when it got the copy stateid. It will be able to 3018 determine the bytes copied from the coa_bytes_copied in the 3019 CB_OFFLOAD argument. 3021 In either case, if cr_consecutive was not true, there is no assurance 3022 as to exactly which bytes in the range were copied. The client MUST 3023 assume that there exists a mixture of the original contents of the 3024 range and the new bytes. If the COPY wrote past the end of the file 3025 on the destination, then the last byte written to will determine the 3026 new file size. The contents of any block not written to and past the 3027 original size of the file will be as if a normal WRITE extended the 3028 file. 3030 15.3. Operation 61: COPY_NOTIFY - Notify a source server of a future 3031 copy 3033 15.3.1. ARGUMENT 3035 3037 struct COPY_NOTIFY4args { 3038 /* CURRENT_FH: source file */ 3039 stateid4 cna_src_stateid; 3040 netloc4 cna_destination_server; 3041 }; 3043 3045 15.3.2. RESULT 3047 3048 struct COPY_NOTIFY4resok { 3049 nfstime4 cnr_lease_time; 3050 stateid4 cnr_stateid; 3051 netloc4 cnr_source_server<>; 3052 }; 3054 union COPY_NOTIFY4res switch (nfsstat4 cnr_status) { 3055 case NFS4_OK: 3056 COPY_NOTIFY4resok resok4; 3057 default: 3058 void; 3059 }; 3061 3063 15.3.3. DESCRIPTION 3065 This operation is used for an inter-server copy. A client sends this 3066 operation in a COMPOUND request to the source server to authorize a 3067 destination server identified by cna_destination_server to read the 3068 file specified by CURRENT_FH on behalf of the given user. 3070 The cna_src_stateid MUST refer to either open or locking states 3071 provided earlier by the server. If it is invalid, then the operation 3072 MUST fail. 3074 The cna_destination_server MUST be specified using the netloc4 3075 network location format. The server is not required to resolve the 3076 cna_destination_server address before completing this operation. 3078 If this operation succeeds, the source server will allow the 3079 cna_destination_server to copy the specified file on behalf of the 3080 given user as long as both of the following conditions are met: 3082 o The destination server begins reading the source file before the 3083 cnr_lease_time expires. If the cnr_lease_time expires while the 3084 destination server is still reading the source file, the 3085 destination server is allowed to finish reading the file. 3087 o The client has not issued a OFFLOAD_CANCEL for the same 3088 combination of user, filehandle, and destination server. 3090 The cnr_lease_time is chosen by the source server. A cnr_lease_time 3091 of 0 (zero) indicates an infinite lease. To avoid the need for 3092 synchronized clocks, copy lease times are granted by the server as a 3093 time delta. To renew the copy lease time the client should resend 3094 the same copy notification request to the source server. 3096 The cnr_stateid is a copy stateid which uniquely describes the state 3097 needed on the source server to track the proposed copy. As defined 3098 in Section 8.2 of [RFC5661], a stateid is tied to the current 3099 filehandle and if the same stateid is presented by two different 3100 clients, it may refer to different state. As the source does not 3101 know which netloc4 network location the destinaton might use to 3102 establish the copy operation, it can use the cnr_stateid to identify 3103 that the destination is operating on behalf of the client. Thus the 3104 source server SHOULD construct copy stateids such that they are 3105 unique from all other stateids handed out to clients. These copy 3106 stateids MUST equate to each of the earlier delegation, locking, and 3107 open states for the client on the given file (see Section 4.4.1). 3109 A successful response will also contain a list of netloc4 network 3110 location formats called cnr_source_server, on which the source is 3111 willing to accept connections from the destination. These might not 3112 be reachable from the client and might be located on networks to 3113 which the client has no connection. 3115 For a copy only involving one server (the source and destination are 3116 on the same server), this operation is unnecessary. 3118 15.4. Operation 62: DEALLOCATE - Unreserve Space in a Region of a File 3120 15.4.1. ARGUMENT 3122 3124 struct DEALLOCATE4args { 3125 /* CURRENT_FH: file */ 3126 stateid4 da_stateid; 3127 offset4 da_offset; 3128 length4 da_length; 3129 }; 3131 3133 15.4.2. RESULT 3135 3137 struct DEALLOCATE4res { 3138 nfsstat4 dr_status; 3139 }; 3140 3142 15.4.3. DESCRIPTION 3144 Whenever a client wishes to unreserve space for a region in a file it 3145 calls the DEALLOCATE operation with the current filehandle set to the 3146 filehandle of the file in question, and the start offset and length 3147 in bytes of the region set in da_offset and da_length respectively. 3148 If no space was allocated or reserved for all or parts of the region, 3149 the DEALLOCATE operation will have no effect for the region that 3150 already is in unreserved state. All further reads from the region 3151 passed to DEALLOCATE MUST return zeros until overwritten. The 3152 filehandle specified must be that of a regular file. 3154 Situations may arise where da_offset and/or da_offset + da_length 3155 will not be aligned to a boundary for which the server does 3156 allocations or deallocations. For most file systems, this is the 3157 block size of the file system. In such a case, the server can 3158 deallocate as many bytes as it can in the region. The blocks that 3159 cannot be deallocated MUST be zeroed. 3161 DEALLOCATE will result in the space_used attribute being decreased by 3162 the number of bytes that were deallocated. The space_freed attribute 3163 may or may not decrease, depending on the support and whether the 3164 blocks backing the specified range were shared or not. The size 3165 attribute will remain unchanged. 3167 15.5. Operation 63: IO_ADVISE - Application I/O access pattern hints 3169 15.5.1. ARGUMENT 3171 3173 enum IO_ADVISE_type4 { 3174 IO_ADVISE4_NORMAL = 0, 3175 IO_ADVISE4_SEQUENTIAL = 1, 3176 IO_ADVISE4_SEQUENTIAL_BACKWARDS = 2, 3177 IO_ADVISE4_RANDOM = 3, 3178 IO_ADVISE4_WILLNEED = 4, 3179 IO_ADVISE4_WILLNEED_OPPORTUNISTIC = 5, 3180 IO_ADVISE4_DONTNEED = 6, 3181 IO_ADVISE4_NOREUSE = 7, 3182 IO_ADVISE4_READ = 8, 3183 IO_ADVISE4_WRITE = 9, 3184 IO_ADVISE4_INIT_PROXIMITY = 10 3185 }; 3186 struct IO_ADVISE4args { 3187 /* CURRENT_FH: file */ 3188 stateid4 iaa_stateid; 3189 offset4 iaa_offset; 3190 length4 iaa_count; 3191 bitmap4 iaa_hints; 3192 }; 3194 3196 15.5.2. RESULT 3198 3200 struct IO_ADVISE4resok { 3201 bitmap4 ior_hints; 3202 }; 3204 union IO_ADVISE4res switch (nfsstat4 ior_status) { 3205 case NFS4_OK: 3206 IO_ADVISE4resok resok4; 3207 default: 3208 void; 3209 }; 3211 3213 15.5.3. DESCRIPTION 3215 The IO_ADVISE operation sends an I/O access pattern hint to the 3216 server for the owner of the stateid for a given byte range specified 3217 by iar_offset and iar_count. The byte range specified by iaa_offset 3218 and iaa_count need not currently exist in the file, but the iaa_hints 3219 will apply to the byte range when it does exist. If iaa_count is 0, 3220 all data following iaa_offset is specified. The server MAY ignore 3221 the advice. 3223 The following are the allowed hints for a stateid holder: 3225 IO_ADVISE4_NORMAL There is no advice to give, this is the default 3226 behavior. 3228 IO_ADVISE4_SEQUENTIAL Expects to access the specified data 3229 sequentially from lower offsets to higher offsets. 3231 IO_ADVISE4_SEQUENTIAL_BACKWARDS Expects to access the specified data 3232 sequentially from higher offsets to lower offsets. 3234 IO_ADVISE4_RANDOM Expects to access the specified data in a random 3235 order. 3237 IO_ADVISE4_WILLNEED Expects to access the specified data in the near 3238 future. 3240 IO_ADVISE4_WILLNEED_OPPORTUNISTIC Expects to possibly access the 3241 data in the near future. This is a speculative hint, and 3242 therefore the server should prefetch data or indirect blocks only 3243 if it can be done at a marginal cost. 3245 IO_ADVISE_DONTNEED Expects that it will not access the specified 3246 data in the near future. 3248 IO_ADVISE_NOREUSE Expects to access the specified data once and then 3249 not reuse it thereafter. 3251 IO_ADVISE4_READ Expects to read the specified data in the near 3252 future. 3254 IO_ADVISE4_WRITE Expects to write the specified data in the near 3255 future. 3257 IO_ADVISE4_INIT_PROXIMITY Informs the server that the data in the 3258 byte range remains important to the client. 3260 Since IO_ADVISE is a hint, a server SHOULD NOT return an error and 3261 invalidate a entire Compound request if one of the sent hints in 3262 iar_hints is not supported by the server. Also, the server MUST NOT 3263 return an error if the client sends contradictory hints to the 3264 server, e.g., IO_ADVISE4_SEQUENTIAL and IO_ADVISE4_RANDOM in a single 3265 IO_ADVISE operation. In these cases, the server MUST return success 3266 and a ior_hints value that indicates the hint it intends to 3267 implement. This may mean simply returning IO_ADVISE4_NORMAL. 3269 The ior_hints returned by the server is primarily for debugging 3270 purposes since the server is under no obligation to carry out the 3271 hints that it describes in the ior_hints result. In addition, while 3272 the server may have intended to implement the hints returned in 3273 ior_hints, as time progresses, the server may need to change its 3274 handling of a given file due to several reasons including, but not 3275 limited to, memory pressure, additional IO_ADVISE hints sent by other 3276 clients, and heuristically detected file access patterns. 3278 The server MAY return different advice than what the client 3279 requested. If it does, then this might be due to one of several 3280 conditions, including, but not limited to another client advising of 3281 a different I/O access pattern; a different I/O access pattern from 3282 another client that that the server has heuristically detected; or 3283 the server is not able to support the requested I/O access pattern, 3284 perhaps due to a temporary resource limitation. 3286 Each issuance of the IO_ADVISE operation overrides all previous 3287 issuances of IO_ADVISE for a given byte range. This effectively 3288 follows a strategy of last hint wins for a given stateid and byte 3289 range. 3291 Clients should assume that hints included in an IO_ADVISE operation 3292 will be forgotten once the file is closed. 3294 15.5.4. IMPLEMENTATION 3296 The NFS client may choose to issue an IO_ADVISE operation to the 3297 server in several different instances. 3299 The most obvious is in direct response to an application's execution 3300 of posix_fadvise(). In this case, IO_ADVISE4_WRITE and 3301 IO_ADVISE4_READ may be set based upon the type of file access 3302 specified when the file was opened. 3304 15.5.5. IO_ADVISE4_INIT_PROXIMITY 3306 The IO_ADVISE4_INIT_PROXIMITY hint is non-posix in origin and can be 3307 used to convey that the client has recently accessed the byte range 3308 in its own cache. I.e., it has not accessed it on the server, but it 3309 has locally. When the server reaches resource exhaustion, knowing 3310 which data is more important allows the server to make better choices 3311 about which data to, for example purge from a cache, or move to 3312 secondary storage. It also informs the server which delegations are 3313 more important, since if delegations are working correctly, once 3314 delegated to a client and the client has read the content for that 3315 byte range, a server might never receive another read request for 3316 that byte range. 3318 The IO_ADVISE4_INIT_PROXIMITY hint can also be used in a pNFS setting 3319 to let the client inform the metadata server as to the I/O statistics 3320 between the client and the storage devices. The metadata server is 3321 then free to use this information about client I/O to optimize the 3322 data storage location. 3324 This hint is also useful in the case of NFS clients which are network 3325 booting from a server. If the first client to be booted sends this 3326 hint, then it keeps the cache warm for the remaining clients. 3328 15.5.6. pNFS File Layout Data Type Considerations 3330 The IO_ADVISE considerations for pNFS are very similar to the COMMIT 3331 considerations for pNFS. That is, as with COMMIT, some NFS server 3332 implementations prefer IO_ADVISE be done on the DS, and some prefer 3333 it be done on the MDS. 3335 For the file's layout type, it is proposed that NFSv4.2 include an 3336 additional hint NFL42_CARE_IO_ADVISE_THRU_MDS which is valid only on 3337 metadata servers running NFSv4.2 or higher. Any file's layout 3338 obtained from a NFSv4.1 metadata server MUST NOT have 3339 NFL42_UFLG_IO_ADVISE_THRU_MDS set. Any file's layout obtained with a 3340 NFSv4.2 metadata server MAY have NFL42_UFLG_IO_ADVISE_THRU_MDS set. 3341 However, if the layout utilizes NFSv4.1 storage devices, the 3342 IO_ADVISE operation cannot be sent to them. 3344 If NFL42_UFLG_IO_ADVISE_THRU_MDS is set, the client MUST send the 3345 IO_ADVISE operation to the MDS in order for it to be honored by the 3346 DS. Once the MDS receives the IO_ADVISE operation, it will 3347 communicate the advice to each DS. 3349 If NFL42_UFLG_IO_ADVISE_THRU_MDS is not set, then the client SHOULD 3350 send an IO_ADVISE operation to the appropriate DS for the specified 3351 byte range. While the client MAY always send IO_ADVISE to the MDS, 3352 if the server has not set NFL42_UFLG_IO_ADVISE_THRU_MDS, the client 3353 should expect that such an IO_ADVISE is futile. Note that a client 3354 SHOULD use the same set of arguments on each IO_ADVISE sent to a DS 3355 for the same open file reference. 3357 The server is not required to support different advice for different 3358 DS's with the same open file reference. 3360 15.5.6.1. Dense and Sparse Packing Considerations 3362 The IO_ADVISE operation MUST use the iar_offset and byte range as 3363 dictated by the presence or absence of NFL4_UFLG_DENSE. 3365 E.g., if NFL4_UFLG_DENSE is present, and a READ or WRITE to the DS 3366 for iaa_offset 0 really means iaa_offset 10000 in the logical file, 3367 then an IO_ADVISE for iaa_offset 0 means iaa_offset 10000. 3369 E.g., if NFL4_UFLG_DENSE is absent, then a READ or WRITE to the DS 3370 for iaa_offset 0 really means iaa_offset 0 in the logical file, then 3371 an IO_ADVISE for iaa_offset 0 means iaa_offset 0 in the logical file. 3373 E.g., if NFL4_UFLG_DENSE is present, the stripe unit is 1000 bytes 3374 and the stripe count is 10, and the dense DS file is serving 3375 iar_offset 0. A READ or WRITE to the DS for iaa_offsets 0, 1000, 3376 2000, and 3000, really mean iaa_offsets 10000, 20000, 30000, and 3377 40000 (implying a stripe count of 10 and a stripe unit of 1000), then 3378 an IO_ADVISE sent to the same DS with an iaa_offset of 500, and an 3379 iaa_count of 3000 means that the IO_ADVISE applies to these byte 3380 ranges of the dense DS file: 3382 - 500 to 999 3383 - 1000 to 1999 3384 - 2000 to 2999 3385 - 3000 to 3499 3387 I.e., the contiguous range 500 to 3499 as specified in IO_ADVISE. 3389 It also applies to these byte ranges of the logical file: 3391 - 10500 to 10999 (500 bytes) 3392 - 20000 to 20999 (1000 bytes) 3393 - 30000 to 30999 (1000 bytes) 3394 - 40000 to 40499 (500 bytes) 3395 (total 3000 bytes) 3397 E.g., if NFL4_UFLG_DENSE is absent, the stripe unit is 250 bytes, the 3398 stripe count is 4, and the sparse DS file is serving iaa_offset 0. 3399 Then a READ or WRITE to the DS for iaa_offsets 0, 1000, 2000, and 3400 3000, really means iaa_offsets 0, 1000, 2000, and 3000 in the logical 3401 file, keeping in mind that on the DS file, byte ranges 250 to 999, 3402 1250 to 1999, 2250 to 2999, and 3250 to 3999 are not accessible. 3403 Then an IO_ADVISE sent to the same DS with an iaa_offset of 500, and 3404 a iaa_count of 3000 means that the IO_ADVISE applies to these byte 3405 ranges of the logical file and the sparse DS file: 3407 - 500 to 999 (500 bytes) - no effect 3408 - 1000 to 1249 (250 bytes) - effective 3409 - 1250 to 1999 (750 bytes) - no effect 3410 - 2000 to 2249 (250 bytes) - effective 3411 - 2250 to 2999 (750 bytes) - no effect 3412 - 3000 to 3249 (250 bytes) - effective 3413 - 3250 to 3499 (250 bytes) - no effect 3414 (subtotal 2250 bytes) - no effect 3415 (subtotal 750 bytes) - effective 3416 (grand total 3000 bytes) - no effect + effective 3418 If neither of the flags NFL42_UFLG_IO_ADVISE_THRU_MDS and 3419 NFL4_UFLG_DENSE are set in the layout, then any IO_ADVISE request 3420 sent to the data server with a byte range that overlaps stripe unit 3421 that the data server does not serve MUST NOT result in the status 3422 NFS4ERR_PNFS_IO_HOLE. Instead, the response SHOULD be successful and 3423 if the server applies IO_ADVISE hints on any stripe units that 3424 overlap with the specified range, those hints SHOULD be indicated in 3425 the response. 3427 15.6. Operation 64: LAYOUTERROR - Provide Errors for the Layout 3429 15.6.1. ARGUMENT 3431 3433 struct device_error4 { 3434 deviceid4 de_deviceid; 3435 nfsstat4 de_status; 3436 nfs_opnum4 de_opnum; 3437 }; 3439 struct LAYOUTERROR4args { 3440 /* CURRENT_FH: file */ 3441 offset4 lea_offset; 3442 length4 lea_length; 3443 stateid4 lea_stateid; 3444 device_error4 lea_errors<>; 3445 }; 3447 3449 15.6.2. RESULT 3451 3453 struct LAYOUTERROR4res { 3454 nfsstat4 ler_status; 3455 }; 3457 3459 15.6.3. DESCRIPTION 3461 The client can use LAYOUTERROR to inform the metadata server about 3462 errors in its interaction with the layout represented by the current 3463 filehandle, client ID (derived from the session ID in the preceding 3464 SEQUENCE operation), byte-range (lea_offset + lea_length), and 3465 lea_stateid. 3467 Each individual device_error4 describes a single error associated 3468 with a storage device, which is identified via de_deviceid. If the 3469 Layout Type supports NFSv4 operations, then the operation which 3470 returned the error is identified via de_opnum. If the Layout Type 3471 does not support NFSv4 operations, then it MAY chose to either map 3472 the operation onto one of the allowed operations which can be sent to 3473 a storage device with the File Layout Type (see Section 3.3) or it 3474 can signal no support for operations by marking de_opnum with the 3475 ILLEGAL operation. Finally the NFS error value (nfsstat4) 3476 encountered is provided via de_status and may consist of the 3477 following error codes: 3479 NFS4ERR_NXIO: The client was unable to establish any communication 3480 with the storage device. 3482 NFS4ERR_*: The client was able to establish communication with the 3483 storage device and is returning one of the allowed error codes for 3484 the operation denoted by de_opnum. 3486 Note that while the metadata server may return an error associated 3487 with the layout stateid or the open file, it MUST NOT return an error 3488 in the processing of the errors. If LAYOUTERROR is in a compound 3489 before LAYOUTRETURN, it MUST NOT introduce an error other than what 3490 LAYOUTRETURN would already encounter. 3492 15.6.4. IMPLEMENTATION 3494 There are two broad classes of errors, transient and persistent. The 3495 client SHOULD strive to only use this new mechanism to report 3496 persistent errors. It MUST be able to deal with transient issues by 3497 itself. Also, while the client might consider an issue to be 3498 persistent, it MUST be prepared for the metadata server to consider 3499 such issues to be transient. A prime example of this is if the 3500 metadata server fences off a client from either a stateid or a 3501 filehandle. The client will get an error from the storage device and 3502 might relay either NFS4ERR_ACCESS or NFS4ERR_BAD_STATEID back to the 3503 metadata server, with the belief that this is a hard error. If the 3504 metadata server is informed by the client that there is an error, it 3505 can safely ignore that. For it, the mission is accomplished in that 3506 the client has returned a layout that the metadata server had most 3507 likely recalled. 3509 The client might also need to inform the metadata server that it 3510 cannot reach one or more of the storage devices. While the metadata 3511 server can detect the connectivity of both of these paths: 3513 o metadata server to storage device 3515 o metadata server to client 3517 it cannot determine if the client and storage device path is working. 3518 As with the case of the storage device passing errors to the client, 3519 it must be prepared for the metadata server to consider such outages 3520 as being transitory. 3522 Clients are expected to tolerate transient storage device errors, and 3523 hence clients SHOULD NOT use the LAYOUTERROR error handling for 3524 device access problems that may be transient. The methods by which a 3525 client decides whether a device access problem is transient vs 3526 persistent are implementation-specific, but may include retrying I/Os 3527 to a data server under appropriate conditions. 3529 When an I/O fails to a storage device, the client SHOULD retry the 3530 failed I/O via the metadata server. In this situation, before 3531 retrying the I/O, the client SHOULD return the layout, or the 3532 affected portion thereof, and SHOULD indicate which storage device or 3533 devices was problematic. The client needs to do this when the 3534 storage device is being unresponsive in order to fence off any failed 3535 write attempts, and ensure that they do not end up overwriting any 3536 later data being written through the metadata server. If the client 3537 does not do this, the metadata server MAY issue a layout recall 3538 callback in order to perform the retried I/O. 3540 The client needs to be cognizant that since this error handling is 3541 optional in the metadata server, the metadata server may silently 3542 ignore this functionality. Also, as the metadata server may consider 3543 some issues the client reports to be expected, the client might find 3544 it difficult to detect a metadata server which has not implemented 3545 error handling via LAYOUTERROR. 3547 If an metadata server is aware that a storage device is proving 3548 problematic to a client, the metadata server SHOULD NOT include that 3549 storage device in any pNFS layouts sent to that client. If the 3550 metadata server is aware that a storage device is affecting many 3551 clients, then the metadata server SHOULD NOT include that storage 3552 device in any pNFS layouts sent out. If a client asks for a new 3553 layout for the file from the metadata server, it MUST be prepared for 3554 the metadata server to return that storage device in the layout. The 3555 metadata server might not have any choice in using the storage 3556 device, i.e., there might only be one possible layout for the system. 3557 Also, in the case of existing files, the metadata server might have 3558 no choice in which storage devices to hand out to clients. 3560 The metadata server is not required to indefinitely retain per-client 3561 storage device error information. An metadata server is also not 3562 required to automatically reinstate use of a previously problematic 3563 storage device; administrative intervention may be required instead. 3565 15.7. Operation 65: LAYOUTSTATS - Provide Statistics for the Layout 3567 15.7.1. ARGUMENT 3569 3571 struct layoutupdate4 { 3572 layouttype4 lou_type; 3573 opaque lou_body<>; 3574 }; 3576 struct io_info4 { 3577 uint32_t ii_count; 3578 uint64_t ii_bytes; 3579 }; 3581 struct LAYOUTSTATS4args { 3582 /* CURRENT_FH: file */ 3583 offset4 lsa_offset; 3584 length4 lsa_length; 3585 stateid4 lsa_stateid; 3586 io_info4 lsa_read; 3587 io_info4 lsa_write; 3588 deviceid4 lsa_deviceid; 3589 layoutupdate4 lsa_layoutupdate; 3590 }; 3592 3594 15.7.2. RESULT 3596 3598 struct LAYOUTSTATS4res { 3599 nfsstat4 lsr_status; 3600 }; 3602 3604 15.7.3. DESCRIPTION 3606 The client can use LAYOUTSTATS to inform the metadata server about 3607 its interaction with the layout represented by the current 3608 filehandle, client ID (derived from the session ID in the preceding 3609 SEQUENCE operation), byte-range (lsa_offset and lsa_length), and 3610 lsa_stateid. lsa_read and lsa_write allow for non-Layout Type 3611 specific statistics to be reported. lsa_deviceid allows the client 3612 to specify to which storage device the statistics apply. The 3613 remaining information the client is presenting is specific to the 3614 Layout Type and presented in the lsa_layoutupdate field. Each Layout 3615 Type MUST define the contents of lsa_layoutupdate in their respective 3616 specifications. 3618 LAYOUTSTATS can be combined with IO_ADVISE (see Section 15.5) to 3619 augment the decision making process of how the metadata server 3620 handles a file. I.e., IO_ADVISE lets the server know that a byte 3621 range has a certain characteristic, but not necessarily the intensity 3622 of that characteristic. 3624 The client MUST reset the statistics after getting a successfully 3625 reply from the metadata server. The first LAYOUTSTATS sent by the 3626 client SHOULD be from the opening of the file. The choice of how 3627 often to update the metadata server is made by the client. 3629 Note that while the metadata server may return an error associated 3630 with the layout stateid or the open file, it MUST NOT return an error 3631 in the processing of the statistics. 3633 15.8. Operation 66: OFFLOAD_CANCEL - Stop an Offloaded Operation 3635 15.8.1. ARGUMENT 3637 3639 struct OFFLOAD_CANCEL4args { 3640 /* CURRENT_FH: file to cancel */ 3641 stateid4 oca_stateid; 3642 }; 3644 3646 15.8.2. RESULT 3648 3649 struct OFFLOAD_CANCEL4res { 3650 nfsstat4 ocr_status; 3651 }; 3653 3655 15.8.3. DESCRIPTION 3657 OFFLOAD_CANCEL is used by the client to terminate an asynchronous 3658 operation, which is identified both by CURRENT_FH and the 3659 oca_stateid. I.e., there can be multiple offloaded operations acting 3660 on the file, the stateid will identify to the server exactly which 3661 one is to be stopped. Currently there are only two operations which 3662 can decide to be asynchronous: COPY and WRITE_SAME. 3664 In the context of server-to-server copy, the client can send 3665 OFFLOAD_CANCEL to either the source or destination server, albeit 3666 with a different stateid. The client uses OFFLOAD_CANCEL to inform 3667 the destination to stop the active transfer and uses the stateid it 3668 got back from the COPY operation. The client uses OFFLOAD_CANCEL and 3669 the stateid it used in the COPY_NOTIFY to inform the source to not 3670 allow any more copying from the destination. 3672 OFFLOAD_CANCEL is also useful in situations in which the source 3673 server granted a very long or infinite lease on the destination 3674 server's ability to read the source file and all copy operations on 3675 the source file have been completed. 3677 15.9. Operation 67: OFFLOAD_STATUS - Poll for Status of Asynchronous 3678 Operation 3680 15.9.1. ARGUMENT 3682 3684 struct OFFLOAD_STATUS4args { 3685 /* CURRENT_FH: destination file */ 3686 stateid4 osa_stateid; 3687 }; 3689 3691 15.9.2. RESULT 3693 3695 struct OFFLOAD_STATUS4resok { 3696 length4 osr_count; 3697 nfsstat4 osr_complete<1>; 3698 }; 3700 union OFFLOAD_STATUS4res switch (nfsstat4 osr_status) { 3701 case NFS4_OK: 3702 OFFLOAD_STATUS4resok osr_resok4; 3703 default: 3704 void; 3705 }; 3707 3709 15.9.3. DESCRIPTION 3711 OFFLOAD_STATUS can be used by the client to query the progress of an 3712 asynchronous operation, which is identified both by CURRENT_FH and 3713 the osa_stateid. If this operation is successful, the number of 3714 bytes processed are returned to the client in the osr_count field. 3716 If the optional osr_complete field is present, the asynchronous 3717 operation has completed. In this case the status value indicates the 3718 result of the asynchronous operation. In all cases, the server will 3719 also deliver the final results of the asynchronous operation in a 3720 CB_OFFLOAD operation. 3722 The failure of this operation does not indicate the result of the 3723 asynchronous operation in any way. 3725 15.10. Operation 68: READ_PLUS - READ Data or Holes from a File 3727 15.10.1. ARGUMENT 3729 3731 struct READ_PLUS4args { 3732 /* CURRENT_FH: file */ 3733 stateid4 rpa_stateid; 3734 offset4 rpa_offset; 3735 count4 rpa_count; 3736 }; 3737 3739 15.10.2. RESULT 3741 3743 enum data_content4 { 3744 NFS4_CONTENT_DATA = 0, 3745 NFS4_CONTENT_HOLE = 1 3746 }; 3748 struct data_info4 { 3749 offset4 di_offset; 3750 length4 di_length; 3751 }; 3753 struct data4 { 3754 offset4 d_offset; 3755 opaque d_data<>; 3756 }; 3758 union read_plus_content switch (data_content4 rpc_content) { 3759 case NFS4_CONTENT_DATA: 3760 data4 rpc_data; 3761 case NFS4_CONTENT_HOLE: 3762 data_info4 rpc_hole; 3763 default: 3764 void; 3765 }; 3767 /* 3768 * Allow a return of an array of contents. 3769 */ 3770 struct read_plus_res4 { 3771 bool rpr_eof; 3772 read_plus_content rpr_contents<>; 3773 }; 3775 union READ_PLUS4res switch (nfsstat4 rp_status) { 3776 case NFS4_OK: 3777 read_plus_res4 rp_resok4; 3778 default: 3779 void; 3780 }; 3781 3783 15.10.3. DESCRIPTION 3785 The READ_PLUS operation is based upon the NFSv4.1 READ operation (see 3786 Section 18.22 of [RFC5661]) and similarly reads data from the regular 3787 file identified by the current filehandle. 3789 The client provides a rpa_offset of where the READ_PLUS is to start 3790 and a rpa_count of how many bytes are to be read. A rpa_offset of 3791 zero means to read data starting at the beginning of the file. If 3792 rpa_offset is greater than or equal to the size of the file, the 3793 status NFS4_OK is returned with di_length (the data length) set to 3794 zero and eof set to TRUE. 3796 The READ_PLUS result is comprised of an array of rpr_contents, each 3797 of which describe a data_content4 type of data. For NFSv4.2, the 3798 allowed values are data and hole. A server MUST support both the 3799 data type and the hole if it uses READ_PLUS. If it does not want to 3800 support a hole, it MUST use READ. The array contents MUST be 3801 contiguous in the file. 3803 Holes SHOULD be returned in their entirety - clients must be prepared 3804 to get more information than they requested. Both the start and the 3805 end of the hole may exceed what was requested. If data to be 3806 returned is comprised entirely of zeros, then the server SHOULD 3807 return that data as a hole instead. 3809 The server may elect to return adjacent elements of the same type. 3810 For example, if the server has a range of data comprised entirely of 3811 zeros and then a hole, it might want to return two adjacent holes to 3812 the client. 3814 If the client specifies a rpa_count value of zero, the READ_PLUS 3815 succeeds and returns zero bytes of data. In all situations, the 3816 server may choose to return fewer bytes than specified by the client. 3817 The client needs to check for this condition and handle the condition 3818 appropriately. 3820 If the client specifies an rpa_offset and rpa_count value that is 3821 entirely contained within a hole of the file, then the di_offset and 3822 di_length returned MAY be for the entire hole. If the the owner has 3823 a locked byte range covering rpa_offset and rpa_count entirely the 3824 di_offset and di_length MUST NOT be extended outside the locked byte 3825 range. This result is considered valid until the file is changed 3826 (detected via the change attribute). The server MUST provide the 3827 same semantics for the hole as if the client read the region and 3828 received zeroes; the implied holes contents lifetime MUST be exactly 3829 the same as any other read data. 3831 If the client specifies an rpa_offset and rpa_count value that begins 3832 in a non-hole of the file but extends into hole the server should 3833 return an array comprised of both data and a hole. The client MUST 3834 be prepared for the server to return a short read describing just the 3835 data. The client will then issue another READ_PLUS for the remaining 3836 bytes, which the server will respond with information about the hole 3837 in the file. 3839 Except when special stateids are used, the stateid value for a 3840 READ_PLUS request represents a value returned from a previous byte- 3841 range lock or share reservation request or the stateid associated 3842 with a delegation. The stateid identifies the associated owners if 3843 any and is used by the server to verify that the associated locks are 3844 still valid (e.g., have not been revoked). 3846 If the read ended at the end-of-file (formally, in a correctly formed 3847 READ_PLUS operation, if rpa_offset + rpa_count is equal to the size 3848 of the file), or the READ_PLUS operation extends beyond the size of 3849 the file (if rpa_offset + rpa_count is greater than the size of the 3850 file), eof is returned as TRUE; otherwise, it is FALSE. A successful 3851 READ_PLUS of an empty file will always return eof as TRUE. 3853 If the current filehandle is not an ordinary file, an error will be 3854 returned to the client. In the case that the current filehandle 3855 represents an object of type NF4DIR, NFS4ERR_ISDIR is returned. If 3856 the current filehandle designates a symbolic link, NFS4ERR_SYMLINK is 3857 returned. In all other cases, NFS4ERR_WRONG_TYPE is returned. 3859 For a READ_PLUS with a stateid value of all bits equal to zero, the 3860 server MAY allow the READ_PLUS to be serviced subject to mandatory 3861 byte-range locks or the current share deny modes for the file. For a 3862 READ_PLUS with a stateid value of all bits equal to one, the server 3863 MAY allow READ_PLUS operations to bypass locking checks at the 3864 server. 3866 On success, the current filehandle retains its value. 3868 15.10.3.1. Note on Client Support of Arms of the Union 3870 It was decided not to add a means for the client to inform the server 3871 as to which arms of READ_PLUS it would support. In a later minor 3872 version, it may become necessary for the introduction of a new 3873 operation which would allow the client to inform the server as to 3874 whether it supported the new arms of the union of data types 3875 available in READ_PLUS. 3877 15.10.4. IMPLEMENTATION 3879 In general, the IMPLEMENTATION notes for READ in Section 18.22.4 of 3880 [RFC5661] also apply to READ_PLUS. 3882 15.10.4.1. Additional pNFS Implementation Information 3884 With pNFS, the semantics of using READ_PLUS remains the same. Any 3885 data server MAY return a hole result for a READ_PLUS request that it 3886 receives. When a data server chooses to return such a result, it has 3887 the option of returning information for the data stored on that data 3888 server (as defined by the data layout), but it MUST NOT return 3889 results for a byte range that includes data managed by another data 3890 server. 3892 If mandatory locking is enforced, then the data server must also 3893 ensure that to return only information that is within the owner's 3894 locked byte range. 3896 15.10.5. READ_PLUS with Sparse Files Example 3898 The following table describes a sparse file. For each byte range, 3899 the file contains either non-zero data or a hole. In addition, the 3900 server in this example will only create a hole if it is greater than 3901 32K. 3903 +-------------+----------+ 3904 | Byte-Range | Contents | 3905 +-------------+----------+ 3906 | 0-15999 | Hole | 3907 | 16K-31999 | Non-Zero | 3908 | 32K-255999 | Hole | 3909 | 256K-287999 | Non-Zero | 3910 | 288K-353999 | Hole | 3911 | 354K-417999 | Non-Zero | 3912 +-------------+----------+ 3914 Table 5 3916 Under the given circumstances, if a client was to read from the file 3917 with a max read size of 64K, the following will be the results for 3918 the given READ_PLUS calls. This assumes the client has already 3919 opened the file, acquired a valid stateid ('s' in the example), and 3920 just needs to issue READ_PLUS requests. 3922 1. READ_PLUS(s, 0, 64K) --> NFS_OK, eof = false, . Since the first hole is less than the server's 3924 minimum hole size, the first 32K of the file is returned as data 3925 and the remaining 32K is returned as a hole which actually 3926 extends to 256K. 3928 2. READ_PLUS(s, 32K, 64K) --> NFS_OK, eof = false, 3929 The requested range was all zeros, and the current hole begins at 3930 offset 32K and is 224K in length. Note that the client should 3931 not have followed up the previous READ_PLUS request with this one 3932 as the hole information from the previous call extended past what 3933 the client was requesting. 3935 3. READ_PLUS(s, 256K, 64K) --> NFS_OK, eof = false, . Returns an array of the 32K data and 3937 the hole which extends to 354K. 3939 4. READ_PLUS(s, 354K, 64K) --> NFS_OK, eof = true, . Returns the final 64K of data and informs the client 3941 there is no more data in the file. 3943 15.11. Operation 69: SEEK - Find the Next Data or Hole 3945 15.11.1. ARGUMENT 3947 3949 enum data_content4 { 3950 NFS4_CONTENT_DATA = 0, 3951 NFS4_CONTENT_HOLE = 1 3952 }; 3954 struct SEEK4args { 3955 /* CURRENT_FH: file */ 3956 stateid4 sa_stateid; 3957 offset4 sa_offset; 3958 data_content4 sa_what; 3959 }; 3961 3963 15.11.2. RESULT 3965 3967 struct seek_res4 { 3968 bool sr_eof; 3969 offset4 sr_offset; 3970 }; 3971 union SEEK4res switch (nfsstat4 sa_status) { 3972 case NFS4_OK: 3973 seek_res4 resok4; 3974 default: 3975 void; 3976 }; 3978 3980 15.11.3. DESCRIPTION 3982 SEEK is an operation that allows a client to determine the location 3983 of the next data_content4 in a file. It allows an implementation of 3984 the emerging extension to lseek(2) to allow clients to determine the 3985 next hole whilst in data or the next data whilst in a hole. 3987 From the given sa_offset, find the next data_content4 of type sa_what 3988 in the file. If the server can not find a corresponding sa_what, 3989 then the status will still be NFS4_OK, but sr_eof would be TRUE. If 3990 the server can find the sa_what, then the sr_offset is the start of 3991 that content. If the sa_offset is beyond the end of the file, then 3992 SEEK MUST return NFS4ERR_NXIO. 3994 All files MUST have a virtual hole at the end of the file. I.e., if 3995 a filesystem does not support sparse files, then a compound with 3996 {SEEK 0 NFS4_CONTENT_HOLE;} would return a result of {SEEK 1 X;} 3997 where 'X' was the size of the file. 3999 SEEK must follow the same rules for stateids as READ_PLUS 4000 (Section 15.10.3). 4002 15.12. Operation 70: WRITE_SAME - WRITE an ADB Multiple Times to a File 4004 15.12.1. ARGUMENT 4006 4008 enum stable_how4 { 4009 UNSTABLE4 = 0, 4010 DATA_SYNC4 = 1, 4011 FILE_SYNC4 = 2 4012 }; 4013 struct app_data_block4 { 4014 offset4 adb_offset; 4015 length4 adb_block_size; 4016 length4 adb_block_count; 4017 length4 adb_reloff_blocknum; 4018 count4 adb_block_num; 4019 length4 adb_reloff_pattern; 4020 opaque adb_pattern<>; 4021 }; 4023 struct WRITE_SAME4args { 4024 /* CURRENT_FH: file */ 4025 stateid4 wsa_stateid; 4026 stable_how4 wsa_stable; 4027 app_data_block4 wsa_adb; 4028 }; 4030 4032 15.12.2. RESULT 4034 4036 struct write_response4 { 4037 stateid4 wr_callback_id<1>; 4038 length4 wr_count; 4039 stable_how4 wr_committed; 4040 verifier4 wr_writeverf; 4041 }; 4043 union WRITE_SAME4res switch (nfsstat4 wsr_status) { 4044 case NFS4_OK: 4045 write_response4 resok4; 4046 default: 4047 void; 4048 }; 4050 4052 15.12.3. DESCRIPTION 4054 The WRITE_SAME operation writes an application data block to the 4055 regular file identified by the current filehandle (see WRITE SAME 4056 (10) in [T10-SBC2]). The target file is specified by the current 4057 filehandle. The data to be written is specified by an 4058 app_data_block4 structure (Section 8.1.1). The client specifies with 4059 the wsa_stable parameter the method of how the data is to be 4060 processed by the server. It is treated like the stable parameter in 4061 the NFSv4.1 WRITE operation (see Section 18.2 of [RFC5661]). 4063 A successful WRITE_SAME will construct a reply for wr_count, 4064 wr_committed, and wr_writeverf as per the NFSv4.1 WRITE operation 4065 results. If wr_callback_id is set, it indicates an asynchronous 4066 reply (see Section 15.12.3.1). 4068 WRITE_SAME has to support all of the errors which are returned by 4069 WRITE plus NFS4ERR_NOTSUPP, i.e., it is an OPTIONAL operation. If 4070 the client supports WRITE_SAME, it MUST support CB_OFFLOAD. 4072 If the server supports ADBs, then it MUST support the WRITE_SAME 4073 operation. The server has no concept of the structure imposed by the 4074 application. It is only when the application writes to a section of 4075 the file does order get imposed. In order to detect corruption even 4076 before the application utilizes the file, the application will want 4077 to initialize a range of ADBs using WRITE_SAME. 4079 When the client invokes the WRITE_SAME operation, it wants to record 4080 the block structure described by the app_data_block4 on to the file. 4082 When the server receives the WRITE_SAME operation, it MUST populate 4083 adb_block_count ADBs in the file starting at adb_offset. The block 4084 size will be given by adb_block_size. The ADBN (if provided) will 4085 start at adb_reloff_blocknum and each block will be monotonically 4086 numbered starting from adb_block_num in the first block. The pattern 4087 (if provided) will be at adb_reloff_pattern of each block and will be 4088 provided in adb_pattern. 4090 The server SHOULD return an asynchronous result if it can determine 4091 the operation will be long running (see Section 15.12.3.1). Once 4092 either the WRITE_SAME finishes synchronously or the server uses 4093 CB_OFFLOAD to inform the client of the asynchronous completion of the 4094 WRITE_SAME, the server MUST return the ADBs to clients as data. 4096 15.12.3.1. Asynchronous Transactions 4098 ADB initialization may lead to server determining to service the 4099 operation asynchronously. If it decides to do so, it sets the 4100 stateid in wr_callback_id to be that of the wsa_stateid. If it does 4101 not set the wr_callback_id, then the result is synchronous. 4103 When the client determines that the reply will be given 4104 asynchronously, it should not assume anything about the contents of 4105 what it wrote until it is informed by the server that the operation 4106 is complete. It can use OFFLOAD_STATUS (Section 15.9) to monitor the 4107 operation and OFFLOAD_CANCEL (Section 15.8) to cancel the operation. 4108 An example of a asynchronous WRITE_SAME is shown in Figure 6. Note 4109 that as with the COPY operation, WRITE_SAME must provide a stateid 4110 for tracking the asynchronous operation. 4112 Client Server 4113 + + 4114 | | 4115 |--- OPEN ---------------------------->| Client opens 4116 |<------------------------------------/| the file 4117 | | 4118 |--- WRITE_SAME ----------------------->| Client initializes 4119 |<------------------------------------/| an ADB 4120 | | 4121 | | 4122 |--- OFFLOAD_STATUS ------------------>| Client may poll 4123 |<------------------------------------/| for status 4124 | | 4125 | . | Multiple OFFLOAD_STATUS 4126 | . | operations may be sent. 4127 | . | 4128 | | 4129 |<-- CB_OFFLOAD -----------------------| Server reports results 4130 |\------------------------------------>| 4131 | | 4132 |--- CLOSE --------------------------->| Client closes 4133 |<------------------------------------/| the file 4134 | | 4135 | | 4137 Figure 6: An asynchronous WRITE_SAME. 4139 When CB_OFFLOAD informs the client of the successful WRITE_SAME, the 4140 write_response4 embedded in the operation will provide the necessary 4141 information that a synchronous WRITE_SAME would have provided. 4143 Regardless of whether the operation is asynchronous or synchronous, 4144 it MUST still support the COMMIT operation semantics as outlined in 4145 Section 18.3 of [RFC5661]. I.e., COMMIT works on one or more WRITE 4146 operations and the WRITE_SAME operation can appear as several WRITE 4147 operations to the server. The client can use locking operations to 4148 control the behavior on the server with respect to long running 4149 asynchronous write operations. 4151 15.12.3.2. Error Handling of a Partially Complete WRITE_SAME 4153 WRITE_SAME will clone adb_block_count copies of the given ADB in 4154 consecutive order in the file starting at adb_offset. An error can 4155 occur after writing the Nth ADB to the file. WRITE_SAME MUST appear 4156 to populate the range of the file as if the client used WRITE to 4157 transfer the instantiated ADBs. I.e., the contents of the range will 4158 be easy for the client to determine in case of a partially complete 4159 WRITE_SAME. 4161 16. NFSv4.2 Callback Operations 4163 16.1. Operation 15: CB_OFFLOAD - Report results of an asynchronous 4164 operation 4166 16.1.1. ARGUMENT 4168 4170 struct write_response4 { 4171 stateid4 wr_callback_id<1>; 4172 length4 wr_count; 4173 stable_how4 wr_committed; 4174 verifier4 wr_writeverf; 4175 }; 4177 union offload_info4 switch (nfsstat4 coa_status) { 4178 case NFS4_OK: 4179 write_response4 coa_resok4; 4180 default: 4181 length4 coa_bytes_copied; 4182 }; 4184 struct CB_OFFLOAD4args { 4185 nfs_fh4 coa_fh; 4186 stateid4 coa_stateid; 4187 offload_info4 coa_offload_info; 4188 }; 4189 4191 16.1.2. RESULT 4193 4195 struct CB_OFFLOAD4res { 4196 nfsstat4 cor_status; 4197 }; 4199 4201 16.1.3. DESCRIPTION 4203 CB_OFFLOAD is used to report to the client the results of an 4204 asynchronous operation, e.g., Server Side Copy or WRITE_SAME. The 4205 coa_fh and coa_stateid identify the transaction and the coa_status 4206 indicates success or failure. The coa_resok4.wr_callback_id MUST NOT 4207 be set. If the transaction failed, then the coa_bytes_copied 4208 contains the number of bytes copied before the failure occurred. The 4209 coa_bytes_copied value indicates the number of bytes copied but not 4210 which specific bytes have been copied. 4212 If the client supports any of the following operations: 4214 COPY: for both intra-server and inter-server asynchronous copies 4216 WRITE_SAME: for ADB initialization 4218 then the client is REQUIRED to support the CB_OFFLOAD operation. 4220 There is a potential race between the reply to the original 4221 transaction on the forechannel and the CB_OFFLOAD callback on the 4222 backchannel. Sections 2.10.6.3 and 20.9.3 of [RFC5661] describe how 4223 to handle this type of issue. 4225 Upon success, the coa_resok4.wr_count presents for each operation: 4227 COPY: the total number of bytes copied 4229 WRITE_SAME: the same information that a synchronous WRITE_SAME would 4230 provide 4232 17. Security Considerations 4234 NFSv4.2 has all of the security concerns present in NFSv4.1 (see 4235 Section 21 of [RFC5661]) and those present in the Server Side Copy 4236 (see Section 4.10) and in Labeled NFS (see Section 9.7). 4238 18. IANA Considerations 4240 The IANA Considerations for Labeled NFS are addressed in [Quigley14]. 4242 19. References 4244 19.1. Normative References 4246 [NFSv42xdr] 4247 Haynes, T., "Network File System (NFS) Version 4 Minor 4248 Version 2 External Data Representation Standard (XDR) 4249 Description", December 2014. 4251 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 4252 Resource Identifier (URI): Generic Syntax", STD 66, RFC 4253 3986, January 2005. 4255 [RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File 4256 System (NFS) Version 4 Minor Version 1 Protocol", RFC 4257 5661, January 2010. 4259 [RFC5662] Shepler, S., Eisler, M., and D. Noveck, "Network File 4260 System (NFS) Version 4 Minor Version 1 External Data 4261 Representation Standard (XDR) Description", RFC 5662, 4262 January 2010. 4264 [posix_fadvise] 4265 The Open Group, "Section 'posix_fadvise()' of System 4266 Interfaces of The Open Group Base Specifications Issue 6, 4267 IEEE Std 1003.1, 2004 Edition", 2004. 4269 [posix_fallocate] 4270 The Open Group, "Section 'posix_fallocate()' of System 4271 Interfaces of The Open Group Base Specifications Issue 6, 4272 IEEE Std 1003.1, 2004 Edition", 2004. 4274 [rpcsec_gssv3] 4275 Adamson, W. and N. Williams, "Remote Procedure Call (RPC) 4276 Security Version 3", December 2014. 4278 19.2. Informative References 4280 [Ashdown08] 4281 Ashdown, L., "Chapter 15, Validating Database Files and 4282 Backups, of Oracle Database Backup and Recovery User's 4283 Guide 11g Release 1 (11.1)", August 2008. 4285 [BL73] Bell, D. and L. LaPadula, "Secure Computer Systems: 4286 Mathematical Foundations and Model", Technical Report 4287 M74-244, The MITRE Corporation, Bedford, MA, May 1973. 4289 [Baira08] Bairavasundaram, L., Goodson, G., Schroeder, B., Arpaci- 4290 Dusseau, A., and R. Arpaci-Dusseau, "An Analysis of Data 4291 Corruption in the Storage Stack", Proceedings of the 6th 4292 USENIX Symposium on File and Storage Technologies (FAST 4293 '08) , 2008. 4295 [I-D.ietf-nfsv4-rfc3530bis] 4296 Haynes, T. and D. Noveck, "Network File System (NFS) 4297 version 4 Protocol", draft-ietf-nfsv4-rfc3530bis-35 (Work 4298 In Progress), November 2014. 4300 [IESG08] ISEG, "IESG Processing of RFC Errata for the IETF Stream", 4301 2008. 4303 [McDougall07] 4304 McDougall, R. and J. Mauro, "Section 11.4.3, Detecting 4305 Memory Corruption of Solaris Internals", 2007. 4307 [NFSv4-Versioning] 4308 Haynes, T. and D. Noveck, "NFSv4 Version Management", 4309 November 2014. 4311 [Quigley14] 4312 Quigley, D., Lu, J., and T. Haynes, "Registry 4313 Specification for Mandatory Access Control (MAC) Security 4314 Label Formats", draft-ietf-nfsv4-lfs-registry-01 (work in 4315 progress), September 2014. 4317 [RFC1108] Kent, S., "Security Options for the Internet Protocol", 4318 RFC 1108, November 1991. 4320 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 4321 Requirement Levels", March 1997. 4323 [RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the 4324 Internet Protocol", RFC 2401, November 1998. 4326 [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., 4327 Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext 4328 Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. 4330 [RFC4506] Eisler, M., "XDR: External Data Representation Standard", 4331 RFC 4506, May 2006. 4333 [RFC5663] Black, D., Fridella, S., and J. Glasgow, "Parallel NFS 4334 (pNFS) Block/Volume Layout", RFC 5663, January 2010. 4336 [RFC7204] Haynes, T., "Requirements for Labeled NFS", RFC 7204, 4337 April 2014. 4339 [RFC959] Postel, J. and J. Reynolds, "File Transfer Protocol", STD 4340 9, RFC 959, October 1985. 4342 [Strohm11] 4343 Strohm, R., "Chapter 2, Data Blocks, Extents, and 4344 Segments, of Oracle Database Concepts 11g Release 1 4345 (11.1)", January 2011. 4347 [T10-SBC2] 4348 Elliott, R., Ed., "ANSI INCITS 405-2005, Information 4349 Technology - SCSI Block Commands - 2 (SBC-2)", November 4350 2004. 4352 Appendix A. Acknowledgments 4354 Tom Haynes would like to thank NetApp, Inc. for its funding of his 4355 time on this project. 4357 For the pNFS Access Permissions Check, the original draft was by 4358 Sorin Faibish, David Black, Mike Eisler, and Jason Glasgow. The work 4359 was influenced by discussions with Benny Halevy and Bruce Fields. A 4360 review was done by Tom Haynes. 4362 For the Sharing change attribute implementation details with NFSv4 4363 clients, the original draft was by Trond Myklebust. 4365 For the NFS Server Side Copy, the original draft was by James 4366 Lentini, Mike Eisler, Deepak Kenchammana, Anshul Madan, and Rahul 4367 Iyer. Tom Talpey co-authored an unpublished version of that 4368 document. It was also was reviewed by a number of individuals: 4369 Pranoop Erasani, Tom Haynes, Arthur Lent, Trond Myklebust, Dave 4370 Noveck, Theresa Lingutla-Raj, Manjunath Shankararao, Satyam Vaghani, 4371 and Nico Williams. Anna Schumaker's early prototyping experience 4372 helped us avoid some traps. Also, both Olga Kornievskaia and Andy 4373 Adamson brought implementation experience to the use of copy stateids 4374 in inter-server copy. 4376 For the NFS space reservation operations, the original draft was by 4377 Mike Eisler, James Lentini, Manjunath Shankararao, and Rahul Iyer. 4379 For the sparse file support, the original draft was by Dean 4380 Hildebrand and Marc Eshel. Valuable input and advice was received 4381 from Sorin Faibish, Bruce Fields, Benny Halevy, Trond Myklebust, and 4382 Richard Scheffenegger. 4384 For the Application IO Hints, the original draft was by Dean 4385 Hildebrand, Mike Eisler, Trond Myklebust, and Sam Falkner. Some 4386 early reviewers included Benny Halevy and Pranoop Erasani. 4388 For Labeled NFS, the original draft was by David Quigley, James 4389 Morris, Jarret Lu, and Tom Haynes. Peter Staubach, Trond Myklebust, 4390 Stephen Smalley, Sorin Faibish, Nico Williams, and David Black also 4391 contributed in the final push to get this accepted. 4393 Christoph Hellwig was very helpful in getting the WRITE_SAME 4394 semantics to model more of what T10 was doing for WRITE SAME (10) 4395 [T10-SBC2]. And he led the push to get space reservations to more 4396 closely model the posix_fallocate. 4398 Andy Adamson picked up the RPCSEC_GSSv3 work, which enabled both 4399 Labeled NFS and Server Side Copy to be present more secure options. 4401 Christoph Hellwig provided the update to GETDEVICELIST. 4403 During the review process, Talia Reyes-Ortiz helped the sessions run 4404 smoothly. While many people contributed here and there, the core 4405 reviewers were Andy Adamson, Pranoop Erasani, Bruce Fields, Chuck 4406 Lever, Trond Myklebust, David Noveck, Peter Staubach, and Mike 4407 Kupfer. 4409 Appendix B. RFC Editor Notes 4411 [RFC Editor: please remove this section prior to publishing this 4412 document as an RFC] 4414 [RFC Editor: prior to publishing this document as an RFC, please 4415 replace all occurrences of NFSv42xdr with RFCxxxx where xxxx is the 4416 RFC number of the companion XDR document] 4418 Author's Address 4420 Thomas Haynes 4421 Primary Data, Inc. 4422 4300 El Camino Real Ste 100 4423 Los Altos, CA 94022 4424 USA 4426 Phone: +1 408 215 1519 4427 Email: thomas.haynes@primarydata.com