1 .. SPDX-License-Identifier: GPL-2.0 1 .. SPDX-License-Identifier: GPL-2.0
2 2
3 =========================== 3 ===========================
4 Coda Kernel-Venus Interface 4 Coda Kernel-Venus Interface
5 =========================== 5 ===========================
6 6
7 .. Note:: 7 .. Note::
8 8
9 This is one of the technical documents desc 9 This is one of the technical documents describing a component of
10 Coda -- this document describes the client 10 Coda -- this document describes the client kernel-Venus interface.
11 11
12 For more information: 12 For more information:
13 13
14 http://www.coda.cs.cmu.edu 14 http://www.coda.cs.cmu.edu
15 15
16 For user level software needed to run Coda: 16 For user level software needed to run Coda:
17 17
18 ftp://ftp.coda.cs.cmu.edu 18 ftp://ftp.coda.cs.cmu.edu
19 19
20 To run Coda you need to get a user level cache 20 To run Coda you need to get a user level cache manager for the client,
21 named Venus, as well as tools to manipulate AC 21 named Venus, as well as tools to manipulate ACLs, to log in, etc. The
22 client needs to have the Coda filesystem selec 22 client needs to have the Coda filesystem selected in the kernel
23 configuration. 23 configuration.
24 24
25 The server needs a user level server and at pr 25 The server needs a user level server and at present does not depend on
26 kernel support. 26 kernel support.
27 27
28 The Venus kernel interface 28 The Venus kernel interface
29 29
30 Peter J. Braam 30 Peter J. Braam
31 31
32 v1.0, Nov 9, 1997 32 v1.0, Nov 9, 1997
33 33
34 This document describes the communication be 34 This document describes the communication between Venus and kernel
35 level filesystem code needed for the operati 35 level filesystem code needed for the operation of the Coda file sys-
36 tem. This document version is meant to desc 36 tem. This document version is meant to describe the current interface
37 (version 1.0) as well as improvements we env 37 (version 1.0) as well as improvements we envisage.
38 38
39 .. Table of Contents 39 .. Table of Contents
40 40
41 1. Introduction 41 1. Introduction
42 42
43 2. Servicing Coda filesystem calls 43 2. Servicing Coda filesystem calls
44 44
45 3. The message layer 45 3. The message layer
46 46
47 3.1 Implementation details 47 3.1 Implementation details
48 48
49 4. The interface at the call level 49 4. The interface at the call level
50 50
51 4.1 Data structures shared by the kernel 51 4.1 Data structures shared by the kernel and Venus
52 4.2 The pioctl interface 52 4.2 The pioctl interface
53 4.3 root 53 4.3 root
54 4.4 lookup 54 4.4 lookup
55 4.5 getattr 55 4.5 getattr
56 4.6 setattr 56 4.6 setattr
57 4.7 access 57 4.7 access
58 4.8 create 58 4.8 create
59 4.9 mkdir 59 4.9 mkdir
60 4.10 link 60 4.10 link
61 4.11 symlink 61 4.11 symlink
62 4.12 remove 62 4.12 remove
63 4.13 rmdir 63 4.13 rmdir
64 4.14 readlink 64 4.14 readlink
65 4.15 open 65 4.15 open
66 4.16 close 66 4.16 close
67 4.17 ioctl 67 4.17 ioctl
68 4.18 rename 68 4.18 rename
69 4.19 readdir 69 4.19 readdir
70 4.20 vget 70 4.20 vget
71 4.21 fsync 71 4.21 fsync
72 4.22 inactive 72 4.22 inactive
73 4.23 rdwr 73 4.23 rdwr
74 4.24 odymount 74 4.24 odymount
75 4.25 ody_lookup 75 4.25 ody_lookup
76 4.26 ody_expand 76 4.26 ody_expand
77 4.27 prefetch 77 4.27 prefetch
78 4.28 signal 78 4.28 signal
79 79
80 5. The minicache and downcalls 80 5. The minicache and downcalls
81 81
82 5.1 INVALIDATE 82 5.1 INVALIDATE
83 5.2 FLUSH 83 5.2 FLUSH
84 5.3 PURGEUSER 84 5.3 PURGEUSER
85 5.4 ZAPFILE 85 5.4 ZAPFILE
86 5.5 ZAPDIR 86 5.5 ZAPDIR
87 5.6 ZAPVNODE 87 5.6 ZAPVNODE
88 5.7 PURGEFID 88 5.7 PURGEFID
89 5.8 REPLACE 89 5.8 REPLACE
90 90
91 6. Initialization and cleanup 91 6. Initialization and cleanup
92 92
93 6.1 Requirements 93 6.1 Requirements
94 94
95 1. Introduction 95 1. Introduction
96 =============== 96 ===============
97 97
98 A key component in the Coda Distributed File 98 A key component in the Coda Distributed File System is the cache
99 manager, Venus. 99 manager, Venus.
100 100
101 When processes on a Coda enabled system acce 101 When processes on a Coda enabled system access files in the Coda
102 filesystem, requests are directed at the fil 102 filesystem, requests are directed at the filesystem layer in the
103 operating system. The operating system will 103 operating system. The operating system will communicate with Venus to
104 service the request for the process. Venus 104 service the request for the process. Venus manages a persistent
105 client cache and makes remote procedure call 105 client cache and makes remote procedure calls to Coda file servers and
106 related servers (such as authentication serv 106 related servers (such as authentication servers) to service these
107 requests it receives from the operating syst 107 requests it receives from the operating system. When Venus has
108 serviced a request it replies to the operati 108 serviced a request it replies to the operating system with appropriate
109 return codes, and other data related to the 109 return codes, and other data related to the request. Optionally the
110 kernel support for Coda may maintain a minic 110 kernel support for Coda may maintain a minicache of recently processed
111 requests to limit the number of interactions 111 requests to limit the number of interactions with Venus. Venus
112 possesses the facility to inform the kernel 112 possesses the facility to inform the kernel when elements from its
113 minicache are no longer valid. 113 minicache are no longer valid.
114 114
115 This document describes precisely this commu 115 This document describes precisely this communication between the
116 kernel and Venus. The definitions of so cal 116 kernel and Venus. The definitions of so called upcalls and downcalls
117 will be given with the format of the data th 117 will be given with the format of the data they handle. We shall also
118 describe the semantic invariants resulting f 118 describe the semantic invariants resulting from the calls.
119 119
120 Historically Coda was implemented in a BSD f 120 Historically Coda was implemented in a BSD file system in Mach 2.6.
121 The interface between the kernel and Venus i 121 The interface between the kernel and Venus is very similar to the BSD
122 VFS interface. Similar functionality is pro 122 VFS interface. Similar functionality is provided, and the format of
123 the parameters and returned data is very sim 123 the parameters and returned data is very similar to the BSD VFS. This
124 leads to an almost natural environment for i 124 leads to an almost natural environment for implementing a kernel-level
125 filesystem driver for Coda in a BSD system. 125 filesystem driver for Coda in a BSD system. However, other operating
126 systems such as Linux and Windows 95 and NT 126 systems such as Linux and Windows 95 and NT have virtual filesystem
127 with different interfaces. 127 with different interfaces.
128 128
129 To implement Coda on these systems some reve 129 To implement Coda on these systems some reverse engineering of the
130 Venus/Kernel protocol is necessary. Also it 130 Venus/Kernel protocol is necessary. Also it came to light that other
131 systems could profit significantly from cert 131 systems could profit significantly from certain small optimizations
132 and modifications to the protocol. To facili 132 and modifications to the protocol. To facilitate this work as well as
133 to make future ports easier, communication b 133 to make future ports easier, communication between Venus and the
134 kernel should be documented in great detail. 134 kernel should be documented in great detail. This is the aim of this
135 document. 135 document.
136 136
137 2. Servicing Coda filesystem calls 137 2. Servicing Coda filesystem calls
138 =================================== 138 ===================================
139 139
140 The service of a request for a Coda file sys 140 The service of a request for a Coda file system service originates in
141 a process P which accessing a Coda file. It 141 a process P which accessing a Coda file. It makes a system call which
142 traps to the OS kernel. Examples of such cal 142 traps to the OS kernel. Examples of such calls trapping to the kernel
143 are ``read``, ``write``, ``open``, ``close`` 143 are ``read``, ``write``, ``open``, ``close``, ``create``, ``mkdir``,
144 ``rmdir``, ``chmod`` in a Unix ontext. Simi 144 ``rmdir``, ``chmod`` in a Unix ontext. Similar calls exist in the Win32
145 environment, and are named ``CreateFile``. 145 environment, and are named ``CreateFile``.
146 146
147 Generally the operating system handles the r 147 Generally the operating system handles the request in a virtual
148 filesystem (VFS) layer, which is named I/O M 148 filesystem (VFS) layer, which is named I/O Manager in NT and IFS
149 manager in Windows 95. The VFS is responsib 149 manager in Windows 95. The VFS is responsible for partial processing
150 of the request and for locating the specific 150 of the request and for locating the specific filesystem(s) which will
151 service parts of the request. Usually the i 151 service parts of the request. Usually the information in the path
152 assists in locating the correct FS drivers. 152 assists in locating the correct FS drivers. Sometimes after extensive
153 pre-processing, the VFS starts invoking expo 153 pre-processing, the VFS starts invoking exported routines in the FS
154 driver. This is the point where the FS spec 154 driver. This is the point where the FS specific processing of the
155 request starts, and here the Coda specific k 155 request starts, and here the Coda specific kernel code comes into
156 play. 156 play.
157 157
158 The FS layer for Coda must expose and implem 158 The FS layer for Coda must expose and implement several interfaces.
159 First and foremost the VFS must be able to m 159 First and foremost the VFS must be able to make all necessary calls to
160 the Coda FS layer, so the Coda FS driver mus 160 the Coda FS layer, so the Coda FS driver must expose the VFS interface
161 as applicable in the operating system. These 161 as applicable in the operating system. These differ very significantly
162 among operating systems, but share features 162 among operating systems, but share features such as facilities to
163 read/write and create and remove objects. T 163 read/write and create and remove objects. The Coda FS layer services
164 such VFS requests by invoking one or more we 164 such VFS requests by invoking one or more well defined services
165 offered by the cache manager Venus. When th 165 offered by the cache manager Venus. When the replies from Venus have
166 come back to the FS driver, servicing of the 166 come back to the FS driver, servicing of the VFS call continues and
167 finishes with a reply to the kernel's VFS. F 167 finishes with a reply to the kernel's VFS. Finally the VFS layer
168 returns to the process. 168 returns to the process.
169 169
170 As a result of this design a basic interface 170 As a result of this design a basic interface exposed by the FS driver
171 must allow Venus to manage message traffic. 171 must allow Venus to manage message traffic. In particular Venus must
172 be able to retrieve and place messages and t 172 be able to retrieve and place messages and to be notified of the
173 arrival of a new message. The notification m 173 arrival of a new message. The notification must be through a mechanism
174 which does not block Venus since Venus must 174 which does not block Venus since Venus must attend to other tasks even
175 when no messages are waiting or being proces 175 when no messages are waiting or being processed.
176 176
177 **Interfaces of the Coda FS Driver** 177 **Interfaces of the Coda FS Driver**
178 178
179 Furthermore the FS layer provides for a spec 179 Furthermore the FS layer provides for a special path of communication
180 between a user process and Venus, called the 180 between a user process and Venus, called the pioctl interface. The
181 pioctl interface is used for Coda specific s 181 pioctl interface is used for Coda specific services, such as
182 requesting detailed information about the pe 182 requesting detailed information about the persistent cache managed by
183 Venus. Here the involvement of the kernel is 183 Venus. Here the involvement of the kernel is minimal. It identifies
184 the calling process and passes the informati 184 the calling process and passes the information on to Venus. When
185 Venus replies the response is passed back to 185 Venus replies the response is passed back to the caller in unmodified
186 form. 186 form.
187 187
188 Finally Venus allows the kernel FS driver to 188 Finally Venus allows the kernel FS driver to cache the results from
189 certain services. This is done to avoid exc 189 certain services. This is done to avoid excessive context switches
190 and results in an efficient system. However 190 and results in an efficient system. However, Venus may acquire
191 information, for example from the network wh 191 information, for example from the network which implies that cached
192 information must be flushed or replaced. Ven 192 information must be flushed or replaced. Venus then makes a downcall
193 to the Coda FS layer to request flushes or u 193 to the Coda FS layer to request flushes or updates in the cache. The
194 kernel FS driver handles such requests synch 194 kernel FS driver handles such requests synchronously.
195 195
196 Among these interfaces the VFS interface and 196 Among these interfaces the VFS interface and the facility to place,
197 receive and be notified of messages are plat 197 receive and be notified of messages are platform specific. We will
198 not go into the calls exported to the VFS la 198 not go into the calls exported to the VFS layer but we will state the
199 requirements of the message exchange mechani 199 requirements of the message exchange mechanism.
200 200
201 201
202 3. The message layer 202 3. The message layer
203 ===================== 203 =====================
204 204
205 At the lowest level the communication betwee 205 At the lowest level the communication between Venus and the FS driver
206 proceeds through messages. The synchronizat 206 proceeds through messages. The synchronization between processes
207 requesting Coda file service and Venus relie 207 requesting Coda file service and Venus relies on blocking and waking
208 up processes. The Coda FS driver processes 208 up processes. The Coda FS driver processes VFS- and pioctl-requests
209 on behalf of a process P, creates messages f 209 on behalf of a process P, creates messages for Venus, awaits replies
210 and finally returns to the caller. The impl 210 and finally returns to the caller. The implementation of the exchange
211 of messages is platform specific, but the se 211 of messages is platform specific, but the semantics have (so far)
212 appeared to be generally applicable. Data b 212 appeared to be generally applicable. Data buffers are created by the
213 FS Driver in kernel memory on behalf of P an 213 FS Driver in kernel memory on behalf of P and copied to user memory in
214 Venus. 214 Venus.
215 215
216 The FS Driver while servicing P makes upcall 216 The FS Driver while servicing P makes upcalls to Venus. Such an
217 upcall is dispatched to Venus by creating a 217 upcall is dispatched to Venus by creating a message structure. The
218 structure contains the identification of P, 218 structure contains the identification of P, the message sequence
219 number, the size of the request and a pointe 219 number, the size of the request and a pointer to the data in kernel
220 memory for the request. Since the data buff 220 memory for the request. Since the data buffer is re-used to hold the
221 reply from Venus, there is a field for the s 221 reply from Venus, there is a field for the size of the reply. A flags
222 field is used in the message to precisely re 222 field is used in the message to precisely record the status of the
223 message. Additional platform dependent stru 223 message. Additional platform dependent structures involve pointers to
224 determine the position of the message on que 224 determine the position of the message on queues and pointers to
225 synchronization objects. In the upcall rout 225 synchronization objects. In the upcall routine the message structure
226 is filled in, flags are set to 0, and it is 226 is filled in, flags are set to 0, and it is placed on the *pending*
227 queue. The routine calling upcall is respon 227 queue. The routine calling upcall is responsible for allocating the
228 data buffer; its structure will be described 228 data buffer; its structure will be described in the next section.
229 229
230 A facility must exist to notify Venus that t 230 A facility must exist to notify Venus that the message has been
231 created, and implemented using available syn 231 created, and implemented using available synchronization objects in
232 the OS. This notification is done in the upc 232 the OS. This notification is done in the upcall context of the process
233 P. When the message is on the pending queue, 233 P. When the message is on the pending queue, process P cannot proceed
234 in upcall. The (kernel mode) processing of 234 in upcall. The (kernel mode) processing of P in the filesystem
235 request routine must be suspended until Venu 235 request routine must be suspended until Venus has replied. Therefore
236 the calling thread in P is blocked in upcall 236 the calling thread in P is blocked in upcall. A pointer in the
237 message structure will locate the synchroniz 237 message structure will locate the synchronization object on which P is
238 sleeping. 238 sleeping.
239 239
240 Venus detects the notification that a messag 240 Venus detects the notification that a message has arrived, and the FS
241 driver allow Venus to retrieve the message w 241 driver allow Venus to retrieve the message with a getmsg_from_kernel
242 call. This action finishes in the kernel by 242 call. This action finishes in the kernel by putting the message on the
243 queue of processing messages and setting fla 243 queue of processing messages and setting flags to READ. Venus is
244 passed the contents of the data buffer. The 244 passed the contents of the data buffer. The getmsg_from_kernel call
245 now returns and Venus processes the request. 245 now returns and Venus processes the request.
246 246
247 At some later point the FS driver receives a 247 At some later point the FS driver receives a message from Venus,
248 namely when Venus calls sendmsg_to_kernel. 248 namely when Venus calls sendmsg_to_kernel. At this moment the Coda FS
249 driver looks at the contents of the message 249 driver looks at the contents of the message and decides if:
250 250
251 251
252 * the message is a reply for a suspended th 252 * the message is a reply for a suspended thread P. If so it removes
253 the message from the processing queue and 253 the message from the processing queue and marks the message as
254 WRITTEN. Finally, the FS driver unblocks 254 WRITTEN. Finally, the FS driver unblocks P (still in the kernel
255 mode context of Venus) and the sendmsg_to 255 mode context of Venus) and the sendmsg_to_kernel call returns to
256 Venus. The process P will be scheduled a 256 Venus. The process P will be scheduled at some point and continues
257 processing its upcall with the data buffe 257 processing its upcall with the data buffer replaced with the reply
258 from Venus. 258 from Venus.
259 259
260 * The message is a ``downcall``. A downcal 260 * The message is a ``downcall``. A downcall is a request from Venus to
261 the FS Driver. The FS driver processes th 261 the FS Driver. The FS driver processes the request immediately
262 (usually a cache eviction or replacement) 262 (usually a cache eviction or replacement) and when it finishes
263 sendmsg_to_kernel returns. 263 sendmsg_to_kernel returns.
264 264
265 Now P awakes and continues processing upcall 265 Now P awakes and continues processing upcall. There are some
266 subtleties to take account of. First P will 266 subtleties to take account of. First P will determine if it was woken
267 up in upcall by a signal from some other sou 267 up in upcall by a signal from some other source (for example an
268 attempt to terminate P) or as is normally th 268 attempt to terminate P) or as is normally the case by Venus in its
269 sendmsg_to_kernel call. In the normal case, 269 sendmsg_to_kernel call. In the normal case, the upcall routine will
270 deallocate the message structure and return. 270 deallocate the message structure and return. The FS routine can proceed
271 with its processing. 271 with its processing.
272 272
273 273
274 **Sleeping and IPC arrangements** 274 **Sleeping and IPC arrangements**
275 275
276 In case P is woken up by a signal and not by 276 In case P is woken up by a signal and not by Venus, it will first look
277 at the flags field. If the message is not y 277 at the flags field. If the message is not yet READ, the process P can
278 handle its signal without notifying Venus. 278 handle its signal without notifying Venus. If Venus has READ, and
279 the request should not be processed, P can s 279 the request should not be processed, P can send Venus a signal message
280 to indicate that it should disregard the pre 280 to indicate that it should disregard the previous message. Such
281 signals are put in the queue at the head, an 281 signals are put in the queue at the head, and read first by Venus. If
282 the message is already marked as WRITTEN it 282 the message is already marked as WRITTEN it is too late to stop the
283 processing. The VFS routine will now contin 283 processing. The VFS routine will now continue. (-- If a VFS request
284 involves more than one upcall, this can lead 284 involves more than one upcall, this can lead to complicated state, an
285 extra field "handle_signals" could be added 285 extra field "handle_signals" could be added in the message structure
286 to indicate points of no return have been pa 286 to indicate points of no return have been passed.--)
287 287
288 288
289 289
290 3.1. Implementation details 290 3.1. Implementation details
291 ---------------------------- 291 ----------------------------
292 292
293 The Unix implementation of this mechanism ha 293 The Unix implementation of this mechanism has been through the
294 implementation of a character device associa 294 implementation of a character device associated with Coda. Venus
295 retrieves messages by doing a read on the de 295 retrieves messages by doing a read on the device, replies are sent
296 with a write and notification is through the 296 with a write and notification is through the select system call on the
297 file descriptor for the device. The process 297 file descriptor for the device. The process P is kept waiting on an
298 interruptible wait queue object. 298 interruptible wait queue object.
299 299
300 In Windows NT and the DPMI Windows 95 implem 300 In Windows NT and the DPMI Windows 95 implementation a DeviceIoControl
301 call is used. The DeviceIoControl call is d 301 call is used. The DeviceIoControl call is designed to copy buffers
302 from user memory to kernel memory with OPCOD 302 from user memory to kernel memory with OPCODES. The sendmsg_to_kernel
303 is issued as a synchronous call, while the g 303 is issued as a synchronous call, while the getmsg_from_kernel call is
304 asynchronous. Windows EventObjects are used 304 asynchronous. Windows EventObjects are used for notification of
305 message arrival. The process P is kept wait 305 message arrival. The process P is kept waiting on a KernelEvent
306 object in NT and a semaphore in Windows 95. 306 object in NT and a semaphore in Windows 95.
307 307
308 308
309 4. The interface at the call level 309 4. The interface at the call level
310 =================================== 310 ===================================
311 311
312 312
313 This section describes the upcalls a Coda FS 313 This section describes the upcalls a Coda FS driver can make to Venus.
314 Each of these upcalls make use of two struct 314 Each of these upcalls make use of two structures: inputArgs and
315 outputArgs. In pseudo BNF form the structu 315 outputArgs. In pseudo BNF form the structures take the following
316 form:: 316 form::
317 317
318 318
319 struct inputArgs { 319 struct inputArgs {
320 u_long opcode; 320 u_long opcode;
321 u_long unique; /* Keep multipl 321 u_long unique; /* Keep multiple outstanding msgs distinct */
322 u_short pid; /* Co 322 u_short pid; /* Common to all */
323 u_short pgid; /* Co 323 u_short pgid; /* Common to all */
324 struct CodaCred cred; /* Co 324 struct CodaCred cred; /* Common to all */
325 325
326 <union "in" of call dependent part 326 <union "in" of call dependent parts of inputArgs>
327 }; 327 };
328 328
329 struct outputArgs { 329 struct outputArgs {
330 u_long opcode; 330 u_long opcode;
331 u_long unique; /* Keep multi 331 u_long unique; /* Keep multiple outstanding msgs distinct */
332 u_long result; 332 u_long result;
333 333
334 <union "out" of call dependent par 334 <union "out" of call dependent parts of inputArgs>
335 }; 335 };
336 336
337 337
338 338
339 Before going on let us elucidate the role of 339 Before going on let us elucidate the role of the various fields. The
340 inputArgs start with the opcode which define 340 inputArgs start with the opcode which defines the type of service
341 requested from Venus. There are approximatel 341 requested from Venus. There are approximately 30 upcalls at present
342 which we will discuss. The unique field la 342 which we will discuss. The unique field labels the inputArg with a
343 unique number which will identify the messag 343 unique number which will identify the message uniquely. A process and
344 process group id are passed. Finally the cr 344 process group id are passed. Finally the credentials of the caller
345 are included. 345 are included.
346 346
347 Before delving into the specific calls we ne 347 Before delving into the specific calls we need to discuss a variety of
348 data structures shared by the kernel and Ven 348 data structures shared by the kernel and Venus.
349 349
350 350
351 351
352 352
353 4.1. Data structures shared by the kernel and 353 4.1. Data structures shared by the kernel and Venus
354 ---------------------------------------------- 354 ----------------------------------------------------
355 355
356 356
357 The CodaCred structure defines a variety of 357 The CodaCred structure defines a variety of user and group ids as
358 they are set for the calling process. The vu 358 they are set for the calling process. The vuid_t and vgid_t are 32 bit
359 unsigned integers. It also defines group me 359 unsigned integers. It also defines group membership in an array. On
360 Unix the CodaCred has proven sufficient to i 360 Unix the CodaCred has proven sufficient to implement good security
361 semantics for Coda but the structure may hav 361 semantics for Coda but the structure may have to undergo modification
362 for the Windows environment when these matur 362 for the Windows environment when these mature::
363 363
364 struct CodaCred { 364 struct CodaCred {
365 vuid_t cr_uid, cr_euid, cr_suid, c 365 vuid_t cr_uid, cr_euid, cr_suid, cr_fsuid; /* Real, effective, set, fs uid */
366 vgid_t cr_gid, cr_egid, cr_sgid, c 366 vgid_t cr_gid, cr_egid, cr_sgid, cr_fsgid; /* same for groups */
367 vgid_t cr_groups[NGROUPS]; 367 vgid_t cr_groups[NGROUPS]; /* Group membership for caller */
368 }; 368 };
369 369
370 370
371 .. Note:: 371 .. Note::
372 372
373 It is questionable if we need CodaCreds i 373 It is questionable if we need CodaCreds in Venus. Finally Venus
374 doesn't know about groups, although it do 374 doesn't know about groups, although it does create files with the
375 default uid/gid. Perhaps the list of gro 375 default uid/gid. Perhaps the list of group membership is superfluous.
376 376
377 377
378 The next item is the fundamental identifier 378 The next item is the fundamental identifier used to identify Coda
379 files, the ViceFid. A fid of a file uniquel 379 files, the ViceFid. A fid of a file uniquely defines a file or
380 directory in the Coda filesystem within a ce 380 directory in the Coda filesystem within a cell [1]_::
381 381
382 typedef struct ViceFid { 382 typedef struct ViceFid {
383 VolumeId Volume; 383 VolumeId Volume;
384 VnodeId Vnode; 384 VnodeId Vnode;
385 Unique_t Unique; 385 Unique_t Unique;
386 } ViceFid; 386 } ViceFid;
387 387
388 .. [1] A cell is agroup of Coda servers acti 388 .. [1] A cell is agroup of Coda servers acting under the aegis of a single
389 system control machine or SCM. See th 389 system control machine or SCM. See the Coda Administration manual
390 for a detailed description of the rol 390 for a detailed description of the role of the SCM.
391 391
392 Each of the constituent fields: VolumeId, Vn 392 Each of the constituent fields: VolumeId, VnodeId and Unique_t are
393 unsigned 32 bit integers. We envisage that 393 unsigned 32 bit integers. We envisage that a further field will need
394 to be prefixed to identify the Coda cell; th 394 to be prefixed to identify the Coda cell; this will probably take the
395 form of a Ipv6 size IP address naming the Co 395 form of a Ipv6 size IP address naming the Coda cell through DNS.
396 396
397 The next important structure shared between 397 The next important structure shared between Venus and the kernel is
398 the attributes of the file. The following s 398 the attributes of the file. The following structure is used to
399 exchange information. It has room for futur 399 exchange information. It has room for future extensions such as
400 support for device files (currently not pres 400 support for device files (currently not present in Coda)::
401 401
402 402
403 struct coda_timespec { 403 struct coda_timespec {
404 int64_t tv_sec; 404 int64_t tv_sec; /* seconds */
405 long tv_nsec; 405 long tv_nsec; /* nanoseconds */
406 }; 406 };
407 407
408 struct coda_vattr { 408 struct coda_vattr {
409 enum coda_vtype va_type; 409 enum coda_vtype va_type; /* vnode type (for create) */
410 u_short va_mode; 410 u_short va_mode; /* files access mode and type */
411 short va_nlink; 411 short va_nlink; /* number of references to file */
412 vuid_t va_uid; 412 vuid_t va_uid; /* owner user id */
413 vgid_t va_gid; 413 vgid_t va_gid; /* owner group id */
414 long va_fsid; 414 long va_fsid; /* file system id (dev for now) */
415 long va_fileid; 415 long va_fileid; /* file id */
416 u_quad_t va_size; 416 u_quad_t va_size; /* file size in bytes */
417 long va_blocksize; 417 long va_blocksize; /* blocksize preferred for i/o */
418 struct coda_timespec va_atime; 418 struct coda_timespec va_atime; /* time of last access */
419 struct coda_timespec va_mtime; 419 struct coda_timespec va_mtime; /* time of last modification */
420 struct coda_timespec va_ctime; 420 struct coda_timespec va_ctime; /* time file changed */
421 u_long va_gen; 421 u_long va_gen; /* generation number of file */
422 u_long va_flags; 422 u_long va_flags; /* flags defined for file */
423 dev_t va_rdev; 423 dev_t va_rdev; /* device special file represents */
424 u_quad_t va_bytes; 424 u_quad_t va_bytes; /* bytes of disk space held by file */
425 u_quad_t va_filerev; 425 u_quad_t va_filerev; /* file modification number */
426 u_int va_vaflags; 426 u_int va_vaflags; /* operations flags, see below */
427 long va_spare; 427 long va_spare; /* remain quad aligned */
428 }; 428 };
429 429
430 430
431 4.2. The pioctl interface 431 4.2. The pioctl interface
432 -------------------------- 432 --------------------------
433 433
434 434
435 Coda specific requests can be made by applic 435 Coda specific requests can be made by application through the pioctl
436 interface. The pioctl is implemented as an o 436 interface. The pioctl is implemented as an ordinary ioctl on a
437 fictitious file /coda/.CONTROL. The pioctl 437 fictitious file /coda/.CONTROL. The pioctl call opens this file, gets
438 a file handle and makes the ioctl call. Fina 438 a file handle and makes the ioctl call. Finally it closes the file.
439 439
440 The kernel involvement in this is limited to 440 The kernel involvement in this is limited to providing the facility to
441 open and close and pass the ioctl message an 441 open and close and pass the ioctl message and to verify that a path in
442 the pioctl data buffers is a file in a Coda 442 the pioctl data buffers is a file in a Coda filesystem.
443 443
444 The kernel is handed a data packet of the fo 444 The kernel is handed a data packet of the form::
445 445
446 struct { 446 struct {
447 const char *path; 447 const char *path;
448 struct ViceIoctl vidata; 448 struct ViceIoctl vidata;
449 int follow; 449 int follow;
450 } data; 450 } data;
451 451
452 452
453 453
454 where:: 454 where::
455 455
456 456
457 struct ViceIoctl { 457 struct ViceIoctl {
458 caddr_t in, out; /* Dat 458 caddr_t in, out; /* Data to be transferred in, or out */
459 short in_size; /* Siz 459 short in_size; /* Size of input buffer <= 2K */
460 short out_size; /* Max 460 short out_size; /* Maximum size of output buffer, <= 2K */
461 }; 461 };
462 462
463 463
464 464
465 The path must be a Coda file, otherwise the 465 The path must be a Coda file, otherwise the ioctl upcall will not be
466 made. 466 made.
467 467
468 .. Note:: The data structures and code are a 468 .. Note:: The data structures and code are a mess. We need to clean this up.
469 469
470 470
471 **We now proceed to document the individual ca 471 **We now proceed to document the individual calls**:
472 472
473 473
474 4.3. root 474 4.3. root
475 ---------- 475 ----------
476 476
477 477
478 Arguments 478 Arguments
479 in 479 in
480 480
481 empty 481 empty
482 482
483 out:: 483 out::
484 484
485 struct cfs_root_out { 485 struct cfs_root_out {
486 ViceFid VFid; 486 ViceFid VFid;
487 } cfs_root; 487 } cfs_root;
488 488
489 489
490 490
491 Description 491 Description
492 This call is made to Venus during the init 492 This call is made to Venus during the initialization of
493 the Coda filesystem. If the result is zero 493 the Coda filesystem. If the result is zero, the cfs_root structure
494 contains the ViceFid of the root of the Co 494 contains the ViceFid of the root of the Coda filesystem. If a non-zero
495 result is generated, its value is a platfo 495 result is generated, its value is a platform dependent error code
496 indicating the difficulty Venus encountere 496 indicating the difficulty Venus encountered in locating the root of
497 the Coda filesystem. 497 the Coda filesystem.
498 498
499 4.4. lookup 499 4.4. lookup
500 ------------ 500 ------------
501 501
502 502
503 Summary 503 Summary
504 Find the ViceFid and type of an object in 504 Find the ViceFid and type of an object in a directory if it exists.
505 505
506 Arguments 506 Arguments
507 in:: 507 in::
508 508
509 struct cfs_lookup_in { 509 struct cfs_lookup_in {
510 ViceFid VFid; 510 ViceFid VFid;
511 char *name; 511 char *name; /* Place holder for data. */
512 } cfs_lookup; 512 } cfs_lookup;
513 513
514 514
515 515
516 out:: 516 out::
517 517
518 struct cfs_lookup_out { 518 struct cfs_lookup_out {
519 ViceFid VFid; 519 ViceFid VFid;
520 int vtype; 520 int vtype;
521 } cfs_lookup; 521 } cfs_lookup;
522 522
523 523
524 524
525 Description 525 Description
526 This call is made to determine the ViceFid 526 This call is made to determine the ViceFid and filetype of
527 a directory entry. The directory entry re 527 a directory entry. The directory entry requested carries name 'name'
528 and Venus will search the directory identi 528 and Venus will search the directory identified by cfs_lookup_in.VFid.
529 The result may indicate that the name does 529 The result may indicate that the name does not exist, or that
530 difficulty was encountered in finding it ( 530 difficulty was encountered in finding it (e.g. due to disconnection).
531 If the result is zero, the field cfs_looku 531 If the result is zero, the field cfs_lookup_out.VFid contains the
532 targets ViceFid and cfs_lookup_out.vtype t 532 targets ViceFid and cfs_lookup_out.vtype the coda_vtype giving the
533 type of object the name designates. 533 type of object the name designates.
534 534
535 The name of the object is an 8 bit character 535 The name of the object is an 8 bit character string of maximum length
536 CFS_MAXNAMLEN, currently set to 256 (includi 536 CFS_MAXNAMLEN, currently set to 256 (including a 0 terminator.)
537 537
538 It is extremely important to realize that Ve 538 It is extremely important to realize that Venus bitwise ors the field
539 cfs_lookup.vtype with CFS_NOCACHE to indicat 539 cfs_lookup.vtype with CFS_NOCACHE to indicate that the object should
540 not be put in the kernel name cache. 540 not be put in the kernel name cache.
541 541
542 .. Note:: 542 .. Note::
543 543
544 The type of the vtype is currently wrong. 544 The type of the vtype is currently wrong. It should be
545 coda_vtype. Linux does not take note of C 545 coda_vtype. Linux does not take note of CFS_NOCACHE. It should.
546 546
547 547
548 4.5. getattr 548 4.5. getattr
549 ------------- 549 -------------
550 550
551 551
552 Summary Get the attributes of a file. 552 Summary Get the attributes of a file.
553 553
554 Arguments 554 Arguments
555 in:: 555 in::
556 556
557 struct cfs_getattr_in { 557 struct cfs_getattr_in {
558 ViceFid VFid; 558 ViceFid VFid;
559 struct coda_vattr attr; /* 559 struct coda_vattr attr; /* XXXXX */
560 } cfs_getattr; 560 } cfs_getattr;
561 561
562 562
563 563
564 out:: 564 out::
565 565
566 struct cfs_getattr_out { 566 struct cfs_getattr_out {
567 struct coda_vattr attr; 567 struct coda_vattr attr;
568 } cfs_getattr; 568 } cfs_getattr;
569 569
570 570
571 571
572 Description 572 Description
573 This call returns the attributes of the fi 573 This call returns the attributes of the file identified by fid.
574 574
575 Errors 575 Errors
576 Errors can occur if the object with fid do 576 Errors can occur if the object with fid does not exist, is
577 unaccessible or if the caller does not hav 577 unaccessible or if the caller does not have permission to fetch
578 attributes. 578 attributes.
579 579
580 .. Note:: 580 .. Note::
581 581
582 Many kernel FS drivers (Linux, NT and Win 582 Many kernel FS drivers (Linux, NT and Windows 95) need to acquire
583 the attributes as well as the Fid for the 583 the attributes as well as the Fid for the instantiation of an internal
584 "inode" or "FileHandle". A significant i 584 "inode" or "FileHandle". A significant improvement in performance on
585 such systems could be made by combining t 585 such systems could be made by combining the lookup and getattr calls
586 both at the Venus/kernel interaction leve 586 both at the Venus/kernel interaction level and at the RPC level.
587 587
588 The vattr structure included in the input ar 588 The vattr structure included in the input arguments is superfluous and
589 should be removed. 589 should be removed.
590 590
591 591
592 4.6. setattr 592 4.6. setattr
593 ------------- 593 -------------
594 594
595 595
596 Summary 596 Summary
597 Set the attributes of a file. 597 Set the attributes of a file.
598 598
599 Arguments 599 Arguments
600 in:: 600 in::
601 601
602 struct cfs_setattr_in { 602 struct cfs_setattr_in {
603 ViceFid VFid; 603 ViceFid VFid;
604 struct coda_vattr attr; 604 struct coda_vattr attr;
605 } cfs_setattr; 605 } cfs_setattr;
606 606
607 607
608 608
609 609
610 out 610 out
611 611
612 empty 612 empty
613 613
614 Description 614 Description
615 The structure attr is filled with attribut 615 The structure attr is filled with attributes to be changed
616 in BSD style. Attributes not to be change 616 in BSD style. Attributes not to be changed are set to -1, apart from
617 vtype which is set to VNON. Other are set 617 vtype which is set to VNON. Other are set to the value to be assigned.
618 The only attributes which the FS driver ma 618 The only attributes which the FS driver may request to change are the
619 mode, owner, groupid, atime, mtime and cti 619 mode, owner, groupid, atime, mtime and ctime. The return value
620 indicates success or failure. 620 indicates success or failure.
621 621
622 Errors 622 Errors
623 A variety of errors can occur. The object 623 A variety of errors can occur. The object may not exist, may
624 be inaccessible, or permission may not be 624 be inaccessible, or permission may not be granted by Venus.
625 625
626 626
627 4.7. access 627 4.7. access
628 ------------ 628 ------------
629 629
630 630
631 Arguments 631 Arguments
632 in:: 632 in::
633 633
634 struct cfs_access_in { 634 struct cfs_access_in {
635 ViceFid VFid; 635 ViceFid VFid;
636 int flags; 636 int flags;
637 } cfs_access; 637 } cfs_access;
638 638
639 639
640 640
641 out 641 out
642 642
643 empty 643 empty
644 644
645 Description 645 Description
646 Verify if access to the object identified 646 Verify if access to the object identified by VFid for
647 operations described by flags is permitted 647 operations described by flags is permitted. The result indicates if
648 access will be granted. It is important t 648 access will be granted. It is important to remember that Coda uses
649 ACLs to enforce protection and that ultima 649 ACLs to enforce protection and that ultimately the servers, not the
650 clients enforce the security of the system 650 clients enforce the security of the system. The result of this call
651 will depend on whether a token is held by 651 will depend on whether a token is held by the user.
652 652
653 Errors 653 Errors
654 The object may not exist, or the ACL descr 654 The object may not exist, or the ACL describing the protection
655 may not be accessible. 655 may not be accessible.
656 656
657 657
658 4.8. create 658 4.8. create
659 ------------ 659 ------------
660 660
661 661
662 Summary 662 Summary
663 Invoked to create a file 663 Invoked to create a file
664 664
665 Arguments 665 Arguments
666 in:: 666 in::
667 667
668 struct cfs_create_in { 668 struct cfs_create_in {
669 ViceFid VFid; 669 ViceFid VFid;
670 struct coda_vattr attr; 670 struct coda_vattr attr;
671 int excl; 671 int excl;
672 int mode; 672 int mode;
673 char *name; 673 char *name; /* Place holder for data. */
674 } cfs_create; 674 } cfs_create;
675 675
676 676
677 677
678 678
679 out:: 679 out::
680 680
681 struct cfs_create_out { 681 struct cfs_create_out {
682 ViceFid VFid; 682 ViceFid VFid;
683 struct coda_vattr attr; 683 struct coda_vattr attr;
684 } cfs_create; 684 } cfs_create;
685 685
686 686
687 687
688 Description 688 Description
689 This upcall is invoked to request creation 689 This upcall is invoked to request creation of a file.
690 The file will be created in the directory 690 The file will be created in the directory identified by VFid, its name
691 will be name, and the mode will be mode. 691 will be name, and the mode will be mode. If excl is set an error will
692 be returned if the file already exists. I 692 be returned if the file already exists. If the size field in attr is
693 set to zero the file will be truncated. T 693 set to zero the file will be truncated. The uid and gid of the file
694 are set by converting the CodaCred to a ui 694 are set by converting the CodaCred to a uid using a macro CRTOUID
695 (this macro is platform dependent). Upon 695 (this macro is platform dependent). Upon success the VFid and
696 attributes of the file are returned. The 696 attributes of the file are returned. The Coda FS Driver will normally
697 instantiate a vnode, inode or file handle 697 instantiate a vnode, inode or file handle at kernel level for the new
698 object. 698 object.
699 699
700 700
701 Errors 701 Errors
702 A variety of errors can occur. Permissions 702 A variety of errors can occur. Permissions may be insufficient.
703 If the object exists and is not a file the 703 If the object exists and is not a file the error EISDIR is returned
704 under Unix. 704 under Unix.
705 705
706 .. Note:: 706 .. Note::
707 707
708 The packing of parameters is very ineffic 708 The packing of parameters is very inefficient and appears to
709 indicate confusion between the system cal 709 indicate confusion between the system call creat and the VFS operation
710 create. The VFS operation create is only 710 create. The VFS operation create is only called to create new objects.
711 This create call differs from the Unix on 711 This create call differs from the Unix one in that it is not invoked
712 to return a file descriptor. The truncate 712 to return a file descriptor. The truncate and exclusive options,
713 together with the mode, could simply be p 713 together with the mode, could simply be part of the mode as it is
714 under Unix. There should be no flags arg 714 under Unix. There should be no flags argument; this is used in open
715 (2) to return a file descriptor for READ 715 (2) to return a file descriptor for READ or WRITE mode.
716 716
717 The attributes of the directory should be re 717 The attributes of the directory should be returned too, since the size
718 and mtime changed. 718 and mtime changed.
719 719
720 720
721 4.9. mkdir 721 4.9. mkdir
722 ----------- 722 -----------
723 723
724 724
725 Summary 725 Summary
726 Create a new directory. 726 Create a new directory.
727 727
728 Arguments 728 Arguments
729 in:: 729 in::
730 730
731 struct cfs_mkdir_in { 731 struct cfs_mkdir_in {
732 ViceFid VFid; 732 ViceFid VFid;
733 struct coda_vattr attr; 733 struct coda_vattr attr;
734 char *name; 734 char *name; /* Place holder for data. */
735 } cfs_mkdir; 735 } cfs_mkdir;
736 736
737 737
738 738
739 out:: 739 out::
740 740
741 struct cfs_mkdir_out { 741 struct cfs_mkdir_out {
742 ViceFid VFid; 742 ViceFid VFid;
743 struct coda_vattr attr; 743 struct coda_vattr attr;
744 } cfs_mkdir; 744 } cfs_mkdir;
745 745
746 746
747 747
748 748
749 Description 749 Description
750 This call is similar to create but creates 750 This call is similar to create but creates a directory.
751 Only the mode field in the input parameter 751 Only the mode field in the input parameters is used for creation.
752 Upon successful creation, the attr returne 752 Upon successful creation, the attr returned contains the attributes of
753 the new directory. 753 the new directory.
754 754
755 Errors 755 Errors
756 As for create. 756 As for create.
757 757
758 .. Note:: 758 .. Note::
759 759
760 The input parameter should be changed to 760 The input parameter should be changed to mode instead of
761 attributes. 761 attributes.
762 762
763 The attributes of the parent should be retur 763 The attributes of the parent should be returned since the size and
764 mtime changes. 764 mtime changes.
765 765
766 766
767 4.10. link 767 4.10. link
768 ----------- 768 -----------
769 769
770 770
771 Summary 771 Summary
772 Create a link to an existing file. 772 Create a link to an existing file.
773 773
774 Arguments 774 Arguments
775 in:: 775 in::
776 776
777 struct cfs_link_in { 777 struct cfs_link_in {
778 ViceFid sourceFid; 778 ViceFid sourceFid; /* cnode to link *to* */
779 ViceFid destFid; 779 ViceFid destFid; /* Directory in which to place link */
780 char *tname; 780 char *tname; /* Place holder for data. */
781 } cfs_link; 781 } cfs_link;
782 782
783 783
784 784
785 out 785 out
786 786
787 empty 787 empty
788 788
789 Description 789 Description
790 This call creates a link to the sourceFid 790 This call creates a link to the sourceFid in the directory
791 identified by destFid with name tname. Th 791 identified by destFid with name tname. The source must reside in the
792 target's parent, i.e. the source must be h 792 target's parent, i.e. the source must be have parent destFid, i.e. Coda
793 does not support cross directory hard link 793 does not support cross directory hard links. Only the return value is
794 relevant. It indicates success or the typ 794 relevant. It indicates success or the type of failure.
795 795
796 Errors 796 Errors
797 The usual errors can occur. 797 The usual errors can occur.
798 798
799 799
800 4.11. symlink 800 4.11. symlink
801 -------------- 801 --------------
802 802
803 803
804 Summary 804 Summary
805 create a symbolic link 805 create a symbolic link
806 806
807 Arguments 807 Arguments
808 in:: 808 in::
809 809
810 struct cfs_symlink_in { 810 struct cfs_symlink_in {
811 ViceFid VFid; 811 ViceFid VFid; /* Directory to put symlink in */
812 char *srcname; 812 char *srcname;
813 struct coda_vattr attr; 813 struct coda_vattr attr;
814 char *tname; 814 char *tname;
815 } cfs_symlink; 815 } cfs_symlink;
816 816
817 817
818 818
819 out 819 out
820 820
821 none 821 none
822 822
823 Description 823 Description
824 Create a symbolic link. The link is to be 824 Create a symbolic link. The link is to be placed in the
825 directory identified by VFid and named tna 825 directory identified by VFid and named tname. It should point to the
826 pathname srcname. The attributes of the n 826 pathname srcname. The attributes of the newly created object are to
827 be set to attr. 827 be set to attr.
828 828
829 .. Note:: 829 .. Note::
830 830
831 The attributes of the target directory sh 831 The attributes of the target directory should be returned since
832 its size changed. 832 its size changed.
833 833
834 834
835 4.12. remove 835 4.12. remove
836 ------------- 836 -------------
837 837
838 838
839 Summary 839 Summary
840 Remove a file 840 Remove a file
841 841
842 Arguments 842 Arguments
843 in:: 843 in::
844 844
845 struct cfs_remove_in { 845 struct cfs_remove_in {
846 ViceFid VFid; 846 ViceFid VFid;
847 char *name; 847 char *name; /* Place holder for data. */
848 } cfs_remove; 848 } cfs_remove;
849 849
850 850
851 851
852 out 852 out
853 853
854 none 854 none
855 855
856 Description 856 Description
857 Remove file named cfs_remove_in.name in di 857 Remove file named cfs_remove_in.name in directory
858 identified by VFid. 858 identified by VFid.
859 859
860 860
861 .. Note:: 861 .. Note::
862 862
863 The attributes of the directory should be 863 The attributes of the directory should be returned since its
864 mtime and size may change. 864 mtime and size may change.
865 865
866 866
867 4.13. rmdir 867 4.13. rmdir
868 ------------ 868 ------------
869 869
870 870
871 Summary 871 Summary
872 Remove a directory 872 Remove a directory
873 873
874 Arguments 874 Arguments
875 in:: 875 in::
876 876
877 struct cfs_rmdir_in { 877 struct cfs_rmdir_in {
878 ViceFid VFid; 878 ViceFid VFid;
879 char *name; 879 char *name; /* Place holder for data. */
880 } cfs_rmdir; 880 } cfs_rmdir;
881 881
882 882
883 883
884 out 884 out
885 885
886 none 886 none
887 887
888 Description 888 Description
889 Remove the directory with name 'name' from 889 Remove the directory with name 'name' from the directory
890 identified by VFid. 890 identified by VFid.
891 891
892 .. Note:: The attributes of the parent direc 892 .. Note:: The attributes of the parent directory should be returned since
893 its mtime and size may change. 893 its mtime and size may change.
894 894
895 895
896 4.14. readlink 896 4.14. readlink
897 --------------- 897 ---------------
898 898
899 899
900 Summary 900 Summary
901 Read the value of a symbolic link. 901 Read the value of a symbolic link.
902 902
903 Arguments 903 Arguments
904 in:: 904 in::
905 905
906 struct cfs_readlink_in { 906 struct cfs_readlink_in {
907 ViceFid VFid; 907 ViceFid VFid;
908 } cfs_readlink; 908 } cfs_readlink;
909 909
910 910
911 911
912 out:: 912 out::
913 913
914 struct cfs_readlink_out { 914 struct cfs_readlink_out {
915 int count; 915 int count;
916 caddr_t data; 916 caddr_t data; /* Place holder for data. */
917 } cfs_readlink; 917 } cfs_readlink;
918 918
919 919
920 920
921 Description 921 Description
922 This routine reads the contents of symboli 922 This routine reads the contents of symbolic link
923 identified by VFid into the buffer data. 923 identified by VFid into the buffer data. The buffer data must be able
924 to hold any name up to CFS_MAXNAMLEN (PATH 924 to hold any name up to CFS_MAXNAMLEN (PATH or NAM??).
925 925
926 Errors 926 Errors
927 No unusual errors. 927 No unusual errors.
928 928
929 929
930 4.15. open 930 4.15. open
931 ----------- 931 -----------
932 932
933 933
934 Summary 934 Summary
935 Open a file. 935 Open a file.
936 936
937 Arguments 937 Arguments
938 in:: 938 in::
939 939
940 struct cfs_open_in { 940 struct cfs_open_in {
941 ViceFid VFid; 941 ViceFid VFid;
942 int flags; 942 int flags;
943 } cfs_open; 943 } cfs_open;
944 944
945 945
946 946
947 out:: 947 out::
948 948
949 struct cfs_open_out { 949 struct cfs_open_out {
950 dev_t dev; 950 dev_t dev;
951 ino_t inode; 951 ino_t inode;
952 } cfs_open; 952 } cfs_open;
953 953
954 954
955 955
956 Description 956 Description
957 This request asks Venus to place the file 957 This request asks Venus to place the file identified by
958 VFid in its cache and to note that the cal 958 VFid in its cache and to note that the calling process wishes to open
959 it with flags as in open(2). The return v 959 it with flags as in open(2). The return value to the kernel differs
960 for Unix and Windows systems. For Unix sy 960 for Unix and Windows systems. For Unix systems the Coda FS Driver is
961 informed of the device and inode number of 961 informed of the device and inode number of the container file in the
962 fields dev and inode. For Windows the pat 962 fields dev and inode. For Windows the path of the container file is
963 returned to the kernel. 963 returned to the kernel.
964 964
965 965
966 .. Note:: 966 .. Note::
967 967
968 Currently the cfs_open_out structure is n 968 Currently the cfs_open_out structure is not properly adapted to
969 deal with the Windows case. It might be 969 deal with the Windows case. It might be best to implement two
970 upcalls, one to open aiming at a containe 970 upcalls, one to open aiming at a container file name, the other at a
971 container file inode. 971 container file inode.
972 972
973 973
974 4.16. close 974 4.16. close
975 ------------ 975 ------------
976 976
977 977
978 Summary 978 Summary
979 Close a file, update it on the servers. 979 Close a file, update it on the servers.
980 980
981 Arguments 981 Arguments
982 in:: 982 in::
983 983
984 struct cfs_close_in { 984 struct cfs_close_in {
985 ViceFid VFid; 985 ViceFid VFid;
986 int flags; 986 int flags;
987 } cfs_close; 987 } cfs_close;
988 988
989 989
990 990
991 out 991 out
992 992
993 none 993 none
994 994
995 Description 995 Description
996 Close the file identified by VFid. 996 Close the file identified by VFid.
997 997
998 .. Note:: 998 .. Note::
999 999
1000 The flags argument is bogus and not used 1000 The flags argument is bogus and not used. However, Venus' code
1001 has room to deal with an execp input fie 1001 has room to deal with an execp input field, probably this field should
1002 be used to inform Venus that the file wa 1002 be used to inform Venus that the file was closed but is still memory
1003 mapped for execution. There are comment 1003 mapped for execution. There are comments about fetching versus not
1004 fetching the data in Venus vproc_vfscall 1004 fetching the data in Venus vproc_vfscalls. This seems silly. If a
1005 file is being closed, the data in the co 1005 file is being closed, the data in the container file is to be the new
1006 data. Here again the execp flag might b 1006 data. Here again the execp flag might be in play to create confusion:
1007 currently Venus might think a file can b 1007 currently Venus might think a file can be flushed from the cache when
1008 it is still memory mapped. This needs t 1008 it is still memory mapped. This needs to be understood.
1009 1009
1010 1010
1011 4.17. ioctl 1011 4.17. ioctl
1012 ------------ 1012 ------------
1013 1013
1014 1014
1015 Summary 1015 Summary
1016 Do an ioctl on a file. This includes the 1016 Do an ioctl on a file. This includes the pioctl interface.
1017 1017
1018 Arguments 1018 Arguments
1019 in:: 1019 in::
1020 1020
1021 struct cfs_ioctl_in { 1021 struct cfs_ioctl_in {
1022 ViceFid VFid; 1022 ViceFid VFid;
1023 int cmd; 1023 int cmd;
1024 int len; 1024 int len;
1025 int rwflag; 1025 int rwflag;
1026 char *data; 1026 char *data; /* Place holder for data. */
1027 } cfs_ioctl; 1027 } cfs_ioctl;
1028 1028
1029 1029
1030 1030
1031 out:: 1031 out::
1032 1032
1033 1033
1034 struct cfs_ioctl_out { 1034 struct cfs_ioctl_out {
1035 int len; 1035 int len;
1036 caddr_t data; 1036 caddr_t data; /* Place holder for data. */
1037 } cfs_ioctl; 1037 } cfs_ioctl;
1038 1038
1039 1039
1040 1040
1041 Description 1041 Description
1042 Do an ioctl operation on a file. The com 1042 Do an ioctl operation on a file. The command, len and
1043 data arguments are filled as usual. flag 1043 data arguments are filled as usual. flags is not used by Venus.
1044 1044
1045 .. Note:: 1045 .. Note::
1046 1046
1047 Another bogus parameter. flags is not u 1047 Another bogus parameter. flags is not used. What is the
1048 business about PREFETCHING in the Venus 1048 business about PREFETCHING in the Venus code?
1049 1049
1050 1050
1051 1051
1052 4.18. rename 1052 4.18. rename
1053 ------------- 1053 -------------
1054 1054
1055 1055
1056 Summary 1056 Summary
1057 Rename a fid. 1057 Rename a fid.
1058 1058
1059 Arguments 1059 Arguments
1060 in:: 1060 in::
1061 1061
1062 struct cfs_rename_in { 1062 struct cfs_rename_in {
1063 ViceFid sourceFid; 1063 ViceFid sourceFid;
1064 char *srcname; 1064 char *srcname;
1065 ViceFid destFid; 1065 ViceFid destFid;
1066 char *destname; 1066 char *destname;
1067 } cfs_rename; 1067 } cfs_rename;
1068 1068
1069 1069
1070 1070
1071 out 1071 out
1072 1072
1073 none 1073 none
1074 1074
1075 Description 1075 Description
1076 Rename the object with name srcname in di 1076 Rename the object with name srcname in directory
1077 sourceFid to destname in destFid. It is 1077 sourceFid to destname in destFid. It is important that the names
1078 srcname and destname are 0 terminated str 1078 srcname and destname are 0 terminated strings. Strings in Unix
1079 kernels are not always null terminated. 1079 kernels are not always null terminated.
1080 1080
1081 1081
1082 4.19. readdir 1082 4.19. readdir
1083 -------------- 1083 --------------
1084 1084
1085 1085
1086 Summary 1086 Summary
1087 Read directory entries. 1087 Read directory entries.
1088 1088
1089 Arguments 1089 Arguments
1090 in:: 1090 in::
1091 1091
1092 struct cfs_readdir_in { 1092 struct cfs_readdir_in {
1093 ViceFid VFid; 1093 ViceFid VFid;
1094 int count; 1094 int count;
1095 int offset; 1095 int offset;
1096 } cfs_readdir; 1096 } cfs_readdir;
1097 1097
1098 1098
1099 1099
1100 1100
1101 out:: 1101 out::
1102 1102
1103 struct cfs_readdir_out { 1103 struct cfs_readdir_out {
1104 int size; 1104 int size;
1105 caddr_t data; 1105 caddr_t data; /* Place holder for data. */
1106 } cfs_readdir; 1106 } cfs_readdir;
1107 1107
1108 1108
1109 1109
1110 Description 1110 Description
1111 Read directory entries from VFid starting 1111 Read directory entries from VFid starting at offset and
1112 read at most count bytes. Returns the da 1112 read at most count bytes. Returns the data in data and returns
1113 the size in size. 1113 the size in size.
1114 1114
1115 1115
1116 .. Note:: 1116 .. Note::
1117 1117
1118 This call is not used. Readdir operatio 1118 This call is not used. Readdir operations exploit container
1119 files. We will re-evaluate this during 1119 files. We will re-evaluate this during the directory revamp which is
1120 about to take place. 1120 about to take place.
1121 1121
1122 1122
1123 4.20. vget 1123 4.20. vget
1124 ----------- 1124 -----------
1125 1125
1126 1126
1127 Summary 1127 Summary
1128 instructs Venus to do an FSDB->Get. 1128 instructs Venus to do an FSDB->Get.
1129 1129
1130 Arguments 1130 Arguments
1131 in:: 1131 in::
1132 1132
1133 struct cfs_vget_in { 1133 struct cfs_vget_in {
1134 ViceFid VFid; 1134 ViceFid VFid;
1135 } cfs_vget; 1135 } cfs_vget;
1136 1136
1137 1137
1138 1138
1139 out:: 1139 out::
1140 1140
1141 struct cfs_vget_out { 1141 struct cfs_vget_out {
1142 ViceFid VFid; 1142 ViceFid VFid;
1143 int vtype; 1143 int vtype;
1144 } cfs_vget; 1144 } cfs_vget;
1145 1145
1146 1146
1147 1147
1148 Description 1148 Description
1149 This upcall asks Venus to do a get operat 1149 This upcall asks Venus to do a get operation on an fsobj
1150 labelled by VFid. 1150 labelled by VFid.
1151 1151
1152 .. Note:: 1152 .. Note::
1153 1153
1154 This operation is not used. However, it 1154 This operation is not used. However, it is extremely useful
1155 since it can be used to deal with read/w 1155 since it can be used to deal with read/write memory mapped files.
1156 These can be "pinned" in the Venus cache 1156 These can be "pinned" in the Venus cache using vget and released with
1157 inactive. 1157 inactive.
1158 1158
1159 1159
1160 4.21. fsync 1160 4.21. fsync
1161 ------------ 1161 ------------
1162 1162
1163 1163
1164 Summary 1164 Summary
1165 Tell Venus to update the RVM attributes o 1165 Tell Venus to update the RVM attributes of a file.
1166 1166
1167 Arguments 1167 Arguments
1168 in:: 1168 in::
1169 1169
1170 struct cfs_fsync_in { 1170 struct cfs_fsync_in {
1171 ViceFid VFid; 1171 ViceFid VFid;
1172 } cfs_fsync; 1172 } cfs_fsync;
1173 1173
1174 1174
1175 1175
1176 out 1176 out
1177 1177
1178 none 1178 none
1179 1179
1180 Description 1180 Description
1181 Ask Venus to update RVM attributes of obj 1181 Ask Venus to update RVM attributes of object VFid. This
1182 should be called as part of kernel level 1182 should be called as part of kernel level fsync type calls. The
1183 result indicates if the syncing was succe 1183 result indicates if the syncing was successful.
1184 1184
1185 .. Note:: Linux does not implement this cal 1185 .. Note:: Linux does not implement this call. It should.
1186 1186
1187 1187
1188 4.22. inactive 1188 4.22. inactive
1189 --------------- 1189 ---------------
1190 1190
1191 1191
1192 Summary 1192 Summary
1193 Tell Venus a vnode is no longer in use. 1193 Tell Venus a vnode is no longer in use.
1194 1194
1195 Arguments 1195 Arguments
1196 in:: 1196 in::
1197 1197
1198 struct cfs_inactive_in { 1198 struct cfs_inactive_in {
1199 ViceFid VFid; 1199 ViceFid VFid;
1200 } cfs_inactive; 1200 } cfs_inactive;
1201 1201
1202 1202
1203 1203
1204 out 1204 out
1205 1205
1206 none 1206 none
1207 1207
1208 Description 1208 Description
1209 This operation returns EOPNOTSUPP. 1209 This operation returns EOPNOTSUPP.
1210 1210
1211 .. Note:: This should perhaps be removed. 1211 .. Note:: This should perhaps be removed.
1212 1212
1213 1213
1214 4.23. rdwr 1214 4.23. rdwr
1215 ----------- 1215 -----------
1216 1216
1217 1217
1218 Summary 1218 Summary
1219 Read or write from a file 1219 Read or write from a file
1220 1220
1221 Arguments 1221 Arguments
1222 in:: 1222 in::
1223 1223
1224 struct cfs_rdwr_in { 1224 struct cfs_rdwr_in {
1225 ViceFid VFid; 1225 ViceFid VFid;
1226 int rwflag; 1226 int rwflag;
1227 int count; 1227 int count;
1228 int offset; 1228 int offset;
1229 int ioflag; 1229 int ioflag;
1230 caddr_t data; 1230 caddr_t data; /* Place holder for data. */
1231 } cfs_rdwr; 1231 } cfs_rdwr;
1232 1232
1233 1233
1234 1234
1235 1235
1236 out:: 1236 out::
1237 1237
1238 struct cfs_rdwr_out { 1238 struct cfs_rdwr_out {
1239 int rwflag; 1239 int rwflag;
1240 int count; 1240 int count;
1241 caddr_t data; /* Pl 1241 caddr_t data; /* Place holder for data. */
1242 } cfs_rdwr; 1242 } cfs_rdwr;
1243 1243
1244 1244
1245 1245
1246 Description 1246 Description
1247 This upcall asks Venus to read or write f 1247 This upcall asks Venus to read or write from a file.
1248 1248
1249 1249
1250 .. Note:: 1250 .. Note::
1251 1251
1252 It should be removed since it is against 1252 It should be removed since it is against the Coda philosophy that
1253 read/write operations never reach Venus. 1253 read/write operations never reach Venus. I have been told the
1254 operation does not work. It is not curre 1254 operation does not work. It is not currently used.
1255 1255
1256 1256
1257 1257
1258 4.24. odymount 1258 4.24. odymount
1259 --------------- 1259 ---------------
1260 1260
1261 1261
1262 Summary 1262 Summary
1263 Allows mounting multiple Coda "filesystem 1263 Allows mounting multiple Coda "filesystems" on one Unix mount point.
1264 1264
1265 Arguments 1265 Arguments
1266 in:: 1266 in::
1267 1267
1268 struct ody_mount_in { 1268 struct ody_mount_in {
1269 char *name; 1269 char *name; /* Place holder for data. */
1270 } ody_mount; 1270 } ody_mount;
1271 1271
1272 1272
1273 1273
1274 out:: 1274 out::
1275 1275
1276 struct ody_mount_out { 1276 struct ody_mount_out {
1277 ViceFid VFid; 1277 ViceFid VFid;
1278 } ody_mount; 1278 } ody_mount;
1279 1279
1280 1280
1281 1281
1282 Description 1282 Description
1283 Asks Venus to return the rootfid of a Cod 1283 Asks Venus to return the rootfid of a Coda system named
1284 name. The fid is returned in VFid. 1284 name. The fid is returned in VFid.
1285 1285
1286 .. Note:: 1286 .. Note::
1287 1287
1288 This call was used by David for dynamic 1288 This call was used by David for dynamic sets. It should be
1289 removed since it causes a jungle of poin 1289 removed since it causes a jungle of pointers in the VFS mounting area.
1290 It is not used by Coda proper. Call is 1290 It is not used by Coda proper. Call is not implemented by Venus.
1291 1291
1292 1292
1293 4.25. ody_lookup 1293 4.25. ody_lookup
1294 ----------------- 1294 -----------------
1295 1295
1296 1296
1297 Summary 1297 Summary
1298 Looks up something. 1298 Looks up something.
1299 1299
1300 Arguments 1300 Arguments
1301 in 1301 in
1302 1302
1303 irrelevant 1303 irrelevant
1304 1304
1305 1305
1306 out 1306 out
1307 1307
1308 irrelevant 1308 irrelevant
1309 1309
1310 1310
1311 .. Note:: Gut it. Call is not implemented b 1311 .. Note:: Gut it. Call is not implemented by Venus.
1312 1312
1313 1313
1314 4.26. ody_expand 1314 4.26. ody_expand
1315 ----------------- 1315 -----------------
1316 1316
1317 1317
1318 Summary 1318 Summary
1319 expands something in a dynamic set. 1319 expands something in a dynamic set.
1320 1320
1321 Arguments 1321 Arguments
1322 in 1322 in
1323 1323
1324 irrelevant 1324 irrelevant
1325 1325
1326 out 1326 out
1327 1327
1328 irrelevant 1328 irrelevant
1329 1329
1330 .. Note:: Gut it. Call is not implemented b 1330 .. Note:: Gut it. Call is not implemented by Venus.
1331 1331
1332 1332
1333 4.27. prefetch 1333 4.27. prefetch
1334 --------------- 1334 ---------------
1335 1335
1336 1336
1337 Summary 1337 Summary
1338 Prefetch a dynamic set. 1338 Prefetch a dynamic set.
1339 1339
1340 Arguments 1340 Arguments
1341 1341
1342 in 1342 in
1343 1343
1344 Not documented. 1344 Not documented.
1345 1345
1346 out 1346 out
1347 1347
1348 Not documented. 1348 Not documented.
1349 1349
1350 Description 1350 Description
1351 Venus worker.cc has support for this call 1351 Venus worker.cc has support for this call, although it is
1352 noted that it doesn't work. Not surprisi 1352 noted that it doesn't work. Not surprising, since the kernel does not
1353 have support for it. (ODY_PREFETCH is not 1353 have support for it. (ODY_PREFETCH is not a defined operation).
1354 1354
1355 1355
1356 .. Note:: Gut it. It isn't working and isn' 1356 .. Note:: Gut it. It isn't working and isn't used by Coda.
1357 1357
1358 1358
1359 1359
1360 4.28. signal 1360 4.28. signal
1361 ------------- 1361 -------------
1362 1362
1363 1363
1364 Summary 1364 Summary
1365 Send Venus a signal about an upcall. 1365 Send Venus a signal about an upcall.
1366 1366
1367 Arguments 1367 Arguments
1368 in 1368 in
1369 1369
1370 none 1370 none
1371 1371
1372 out 1372 out
1373 1373
1374 not applicable. 1374 not applicable.
1375 1375
1376 Description 1376 Description
1377 This is an out-of-band upcall to Venus to 1377 This is an out-of-band upcall to Venus to inform Venus
1378 that the calling process received a signa 1378 that the calling process received a signal after Venus read the
1379 message from the input queue. Venus is s 1379 message from the input queue. Venus is supposed to clean up the
1380 operation. 1380 operation.
1381 1381
1382 Errors 1382 Errors
1383 No reply is given. 1383 No reply is given.
1384 1384
1385 .. Note:: 1385 .. Note::
1386 1386
1387 We need to better understand what Venus 1387 We need to better understand what Venus needs to clean up and if
1388 it is doing this correctly. Also we nee 1388 it is doing this correctly. Also we need to handle multiple upcall
1389 per system call situations correctly. I 1389 per system call situations correctly. It would be important to know
1390 what state changes in Venus take place a 1390 what state changes in Venus take place after an upcall for which the
1391 kernel is responsible for notifying Venu 1391 kernel is responsible for notifying Venus to clean up (e.g. open
1392 definitely is such a state change, but m 1392 definitely is such a state change, but many others are maybe not).
1393 1393
1394 1394
1395 5. The minicache and downcalls 1395 5. The minicache and downcalls
1396 =============================== 1396 ===============================
1397 1397
1398 1398
1399 The Coda FS Driver can cache results of loo 1399 The Coda FS Driver can cache results of lookup and access upcalls, to
1400 limit the frequency of upcalls. Upcalls ca 1400 limit the frequency of upcalls. Upcalls carry a price since a process
1401 context switch needs to take place. The co 1401 context switch needs to take place. The counterpart of caching the
1402 information is that Venus will notify the F 1402 information is that Venus will notify the FS Driver that cached
1403 entries must be flushed or renamed. 1403 entries must be flushed or renamed.
1404 1404
1405 The kernel code generally has to maintain a 1405 The kernel code generally has to maintain a structure which links the
1406 internal file handles (called vnodes in BSD 1406 internal file handles (called vnodes in BSD, inodes in Linux and
1407 FileHandles in Windows) with the ViceFid's 1407 FileHandles in Windows) with the ViceFid's which Venus maintains. The
1408 reason is that frequent translations back a 1408 reason is that frequent translations back and forth are needed in
1409 order to make upcalls and use the results o 1409 order to make upcalls and use the results of upcalls. Such linking
1410 objects are called cnodes. 1410 objects are called cnodes.
1411 1411
1412 The current minicache implementations have 1412 The current minicache implementations have cache entries which record
1413 the following: 1413 the following:
1414 1414
1415 1. the name of the file 1415 1. the name of the file
1416 1416
1417 2. the cnode of the directory containing th 1417 2. the cnode of the directory containing the object
1418 1418
1419 3. a list of CodaCred's for which the looku 1419 3. a list of CodaCred's for which the lookup is permitted.
1420 1420
1421 4. the cnode of the object 1421 4. the cnode of the object
1422 1422
1423 The lookup call in the Coda FS Driver may r 1423 The lookup call in the Coda FS Driver may request the cnode of the
1424 desired object from the cache, by passing i 1424 desired object from the cache, by passing its name, directory and the
1425 CodaCred's of the caller. The cache will r 1425 CodaCred's of the caller. The cache will return the cnode or indicate
1426 that it cannot be found. The Coda FS Drive 1426 that it cannot be found. The Coda FS Driver must be careful to
1427 invalidate cache entries when it modifies o 1427 invalidate cache entries when it modifies or removes objects.
1428 1428
1429 When Venus obtains information that indicat 1429 When Venus obtains information that indicates that cache entries are
1430 no longer valid, it will make a downcall to 1430 no longer valid, it will make a downcall to the kernel. Downcalls are
1431 intercepted by the Coda FS Driver and lead 1431 intercepted by the Coda FS Driver and lead to cache invalidations of
1432 the kind described below. The Coda FS Driv 1432 the kind described below. The Coda FS Driver does not return an error
1433 unless the downcall data could not be read 1433 unless the downcall data could not be read into kernel memory.
1434 1434
1435 1435
1436 5.1. INVALIDATE 1436 5.1. INVALIDATE
1437 ---------------- 1437 ----------------
1438 1438
1439 1439
1440 No information is available on this call. 1440 No information is available on this call.
1441 1441
1442 1442
1443 5.2. FLUSH 1443 5.2. FLUSH
1444 ----------- 1444 -----------
1445 1445
1446 1446
1447 1447
1448 Arguments 1448 Arguments
1449 None 1449 None
1450 1450
1451 Summary 1451 Summary
1452 Flush the name cache entirely. 1452 Flush the name cache entirely.
1453 1453
1454 Description 1454 Description
1455 Venus issues this call upon startup and w 1455 Venus issues this call upon startup and when it dies. This
1456 is to prevent stale cache information bei 1456 is to prevent stale cache information being held. Some operating
1457 systems allow the kernel name cache to be 1457 systems allow the kernel name cache to be switched off dynamically.
1458 When this is done, this downcall is made. 1458 When this is done, this downcall is made.
1459 1459
1460 1460
1461 5.3. PURGEUSER 1461 5.3. PURGEUSER
1462 --------------- 1462 ---------------
1463 1463
1464 1464
1465 Arguments 1465 Arguments
1466 :: 1466 ::
1467 1467
1468 struct cfs_purgeuser_out {/* CFS_PU 1468 struct cfs_purgeuser_out {/* CFS_PURGEUSER is a venus->kernel call */
1469 struct CodaCred cred; 1469 struct CodaCred cred;
1470 } cfs_purgeuser; 1470 } cfs_purgeuser;
1471 1471
1472 1472
1473 1473
1474 Description 1474 Description
1475 Remove all entries in the cache carrying 1475 Remove all entries in the cache carrying the Cred. This
1476 call is issued when tokens for a user exp 1476 call is issued when tokens for a user expire or are flushed.
1477 1477
1478 1478
1479 5.4. ZAPFILE 1479 5.4. ZAPFILE
1480 ------------- 1480 -------------
1481 1481
1482 1482
1483 Arguments 1483 Arguments
1484 :: 1484 ::
1485 1485
1486 struct cfs_zapfile_out { /* CFS_ZA 1486 struct cfs_zapfile_out { /* CFS_ZAPFILE is a venus->kernel call */
1487 ViceFid CodaFid; 1487 ViceFid CodaFid;
1488 } cfs_zapfile; 1488 } cfs_zapfile;
1489 1489
1490 1490
1491 1491
1492 Description 1492 Description
1493 Remove all entries which have the (dir vn 1493 Remove all entries which have the (dir vnode, name) pair.
1494 This is issued as a result of an invalida 1494 This is issued as a result of an invalidation of cached attributes of
1495 a vnode. 1495 a vnode.
1496 1496
1497 .. Note:: 1497 .. Note::
1498 1498
1499 Call is not named correctly in NetBSD an 1499 Call is not named correctly in NetBSD and Mach. The minicache
1500 zapfile routine takes different argument 1500 zapfile routine takes different arguments. Linux does not implement
1501 the invalidation of attributes correctly 1501 the invalidation of attributes correctly.
1502 1502
1503 1503
1504 1504
1505 5.5. ZAPDIR 1505 5.5. ZAPDIR
1506 ------------ 1506 ------------
1507 1507
1508 1508
1509 Arguments 1509 Arguments
1510 :: 1510 ::
1511 1511
1512 struct cfs_zapdir_out { /* CFS_ZA 1512 struct cfs_zapdir_out { /* CFS_ZAPDIR is a venus->kernel call */
1513 ViceFid CodaFid; 1513 ViceFid CodaFid;
1514 } cfs_zapdir; 1514 } cfs_zapdir;
1515 1515
1516 1516
1517 1517
1518 Description 1518 Description
1519 Remove all entries in the cache lying in 1519 Remove all entries in the cache lying in a directory
1520 CodaFid, and all children of this directo 1520 CodaFid, and all children of this directory. This call is issued when
1521 Venus receives a callback on the director 1521 Venus receives a callback on the directory.
1522 1522
1523 1523
1524 5.6. ZAPVNODE 1524 5.6. ZAPVNODE
1525 -------------- 1525 --------------
1526 1526
1527 1527
1528 1528
1529 Arguments 1529 Arguments
1530 :: 1530 ::
1531 1531
1532 struct cfs_zapvnode_out { /* CFS_ZA 1532 struct cfs_zapvnode_out { /* CFS_ZAPVNODE is a venus->kernel call */
1533 struct CodaCred cred; 1533 struct CodaCred cred;
1534 ViceFid VFid; 1534 ViceFid VFid;
1535 } cfs_zapvnode; 1535 } cfs_zapvnode;
1536 1536
1537 1537
1538 1538
1539 Description 1539 Description
1540 Remove all entries in the cache carrying 1540 Remove all entries in the cache carrying the cred and VFid
1541 as in the arguments. This downcall is pro 1541 as in the arguments. This downcall is probably never issued.
1542 1542
1543 1543
1544 5.7. PURGEFID 1544 5.7. PURGEFID
1545 -------------- 1545 --------------
1546 1546
1547 1547
1548 Arguments 1548 Arguments
1549 :: 1549 ::
1550 1550
1551 struct cfs_purgefid_out { /* CFS_PU 1551 struct cfs_purgefid_out { /* CFS_PURGEFID is a venus->kernel call */
1552 ViceFid CodaFid; 1552 ViceFid CodaFid;
1553 } cfs_purgefid; 1553 } cfs_purgefid;
1554 1554
1555 1555
1556 1556
1557 Description 1557 Description
1558 Flush the attribute for the file. If it i 1558 Flush the attribute for the file. If it is a dir (odd
1559 vnode), purge its children from the namec 1559 vnode), purge its children from the namecache and remove the file from the
1560 namecache. 1560 namecache.
1561 1561
1562 1562
1563 1563
1564 5.8. REPLACE 1564 5.8. REPLACE
1565 ------------- 1565 -------------
1566 1566
1567 1567
1568 Summary 1568 Summary
1569 Replace the Fid's for a collection of nam 1569 Replace the Fid's for a collection of names.
1570 1570
1571 Arguments 1571 Arguments
1572 :: 1572 ::
1573 1573
1574 struct cfs_replace_out { /* cfs_rep 1574 struct cfs_replace_out { /* cfs_replace is a venus->kernel call */
1575 ViceFid NewFid; 1575 ViceFid NewFid;
1576 ViceFid OldFid; 1576 ViceFid OldFid;
1577 } cfs_replace; 1577 } cfs_replace;
1578 1578
1579 1579
1580 1580
1581 Description 1581 Description
1582 This routine replaces a ViceFid in the na 1582 This routine replaces a ViceFid in the name cache with
1583 another. It is added to allow Venus duri 1583 another. It is added to allow Venus during reintegration to replace
1584 locally allocated temp fids while disconn 1584 locally allocated temp fids while disconnected with global fids even
1585 when the reference counts on those fids a 1585 when the reference counts on those fids are not zero.
1586 1586
1587 1587
1588 6. Initialization and cleanup 1588 6. Initialization and cleanup
1589 ============================== 1589 ==============================
1590 1590
1591 1591
1592 This section gives brief hints as to desira 1592 This section gives brief hints as to desirable features for the Coda
1593 FS Driver at startup and upon shutdown or V 1593 FS Driver at startup and upon shutdown or Venus failures. Before
1594 entering the discussion it is useful to rep 1594 entering the discussion it is useful to repeat that the Coda FS Driver
1595 maintains the following data: 1595 maintains the following data:
1596 1596
1597 1597
1598 1. message queues 1598 1. message queues
1599 1599
1600 2. cnodes 1600 2. cnodes
1601 1601
1602 3. name cache entries 1602 3. name cache entries
1603 1603
1604 The name cache entries are entirely priv 1604 The name cache entries are entirely private to the driver, so they
1605 can easily be manipulated. The message 1605 can easily be manipulated. The message queues will generally have
1606 clear points of initialization and destr 1606 clear points of initialization and destruction. The cnodes are
1607 much more delicate. User processes hold 1607 much more delicate. User processes hold reference counts in Coda
1608 filesystems and it can be difficult to c 1608 filesystems and it can be difficult to clean up the cnodes.
1609 1609
1610 It can expect requests through: 1610 It can expect requests through:
1611 1611
1612 1. the message subsystem 1612 1. the message subsystem
1613 1613
1614 2. the VFS layer 1614 2. the VFS layer
1615 1615
1616 3. pioctl interface 1616 3. pioctl interface
1617 1617
1618 Currently the pioctl passes through the 1618 Currently the pioctl passes through the VFS for Coda so we can
1619 treat these similarly. 1619 treat these similarly.
1620 1620
1621 1621
1622 6.1. Requirements 1622 6.1. Requirements
1623 ------------------ 1623 ------------------
1624 1624
1625 1625
1626 The following requirements should be accomm 1626 The following requirements should be accommodated:
1627 1627
1628 1. The message queues should have open and 1628 1. The message queues should have open and close routines. On Unix
1629 the opening of the character devices are 1629 the opening of the character devices are such routines.
1630 1630
1631 - Before opening, no messages can be pla 1631 - Before opening, no messages can be placed.
1632 1632
1633 - Opening will remove any old messages s 1633 - Opening will remove any old messages still pending.
1634 1634
1635 - Close will notify any sleeping process 1635 - Close will notify any sleeping processes that their upcall cannot
1636 be completed. 1636 be completed.
1637 1637
1638 - Close will free all memory allocated b 1638 - Close will free all memory allocated by the message queues.
1639 1639
1640 1640
1641 2. At open the namecache shall be initializ 1641 2. At open the namecache shall be initialized to empty state.
1642 1642
1643 3. Before the message queues are open, all 1643 3. Before the message queues are open, all VFS operations will fail.
1644 Fortunately this can be achieved by maki 1644 Fortunately this can be achieved by making sure than mounting the
1645 Coda filesystem cannot succeed before op 1645 Coda filesystem cannot succeed before opening.
1646 1646
1647 4. After closing of the queues, no VFS oper 1647 4. After closing of the queues, no VFS operations can succeed. Here
1648 one needs to be careful, since a few ope 1648 one needs to be careful, since a few operations (lookup,
1649 read/write, readdir) can proceed without 1649 read/write, readdir) can proceed without upcalls. These must be
1650 explicitly blocked. 1650 explicitly blocked.
1651 1651
1652 5. Upon closing the namecache shall be flus 1652 5. Upon closing the namecache shall be flushed and disabled.
1653 1653
1654 6. All memory held by cnodes can be freed w 1654 6. All memory held by cnodes can be freed without relying on upcalls.
1655 1655
1656 7. Unmounting the file system can be done w 1656 7. Unmounting the file system can be done without relying on upcalls.
1657 1657
1658 8. Mounting the Coda filesystem should fail 1658 8. Mounting the Coda filesystem should fail gracefully if Venus cannot
1659 get the rootfid or the attributes of the 1659 get the rootfid or the attributes of the rootfid. The latter is
1660 best implemented by Venus fetching these 1660 best implemented by Venus fetching these objects before attempting
1661 to mount. 1661 to mount.
1662 1662
1663 .. Note:: 1663 .. Note::
1664 1664
1665 NetBSD in particular but also Linux have 1665 NetBSD in particular but also Linux have not implemented the
1666 above requirements fully. For smooth op 1666 above requirements fully. For smooth operation this needs to be
1667 corrected. 1667 corrected.
1668 1668
1669 1669
1670 1670
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