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Commit f476c6ed authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Jonathan Corbet
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docs: filesystems: convert coda.txt to ReST 

This document has its own style. It seems to be print output
for the old matrixial printers where backspace were used to
do double prints.

For the conversion, I used several regex expressions to get
rid of some weird stuff. The patch also does almost all possible
conversions in order to get a nice output document, while keeping
it readable/editable as is:

- Add a SPDX header;
- Add a document title;
- Adjust document title;
- Adjust section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Adjust list markups;
- Mark some unumbered titles with bold font;
- Use footnoote markups;
- Add table markups;
- Use notes markups;
- Add it to filesystems/index.rst.
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/25c06c40c3d7b947a131c3be124ce0e93cc00ae3.1588021877.git.mchehab+huawei@kernel.orgSigned-off-by: default avatarJonathan Corbet <corbet@lwn.net>
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Documentation/filesystems/coda.txt → Documentation/filesystems/coda.rst
View file @ f476c6ed
NOTE:
This is one of the technical documents describing a component of
Coda -- this document describes the client kernel-Venus interface.
.. SPDX-License-Identifier: GPL-2.0
===========================
Coda Kernel-Venus Interface
===========================
.. Note::
This is one of the technical documents describing a component of
Coda -- this document describes the client kernel-Venus interface.
For more information:
http://www.coda.cs.cmu.edu
For user level software needed to run Coda:
ftp://ftp.coda.cs.cmu.edu
To run Coda you need to get a user level cache manager for the client,
......@@ -15,77 +25,18 @@ configuration.
The server needs a user level server and at present does not depend on
kernel support.
The Venus kernel interface
Peter J. Braam
v1.0, Nov 9, 1997
This document describes the communication between Venus and kernel
level filesystem code needed for the operation of the Coda file sys-
tem. This document version is meant to describe the current interface
(version 1.0) as well as improvements we envisage.
______________________________________________________________________
Table of Contents
.. Table of Contents
1. Introduction
......@@ -141,17 +92,11 @@ kernel support.
6.1 Requirements
______________________________________________________________________
0wpage
11.. IInnttrroodduuccttiioonn
1. Introduction
===============
A key component in the Coda Distributed File System is the cache
manager, _V_e_n_u_s.
manager, Venus.
When processes on a Coda enabled system access files in the Coda
filesystem, requests are directed at the filesystem layer in the
......@@ -189,16 +134,15 @@ kernel support.
kernel should be documented in great detail. This is the aim of this
document.
0wpage
22.. SSeerrvviicciinngg CCooddaa ffiilleessyysstteemm ccaallllss
2. Servicing Coda filesystem calls
===================================
The service of a request for a Coda file system service originates in
a process PP which accessing a Coda file. It makes a system call which
a process P which accessing a Coda file. It makes a system call which
traps to the OS kernel. Examples of such calls trapping to the kernel
are _r_e_a_d_, _w_r_i_t_e_, _o_p_e_n_, _c_l_o_s_e_, _c_r_e_a_t_e_, _m_k_d_i_r_, _r_m_d_i_r_, _c_h_m_o_d in a Unix
context. Similar calls exist in the Win32 environment, and are named
_C_r_e_a_t_e_F_i_l_e_, .
are ``read``, ``write``, ``open``, ``close``, ``create``, ``mkdir``,
``rmdir``, ``chmod`` in a Unix ontext. Similar calls exist in the Win32
environment, and are named ``CreateFile``.
Generally the operating system handles the request in a virtual
filesystem (VFS) layer, which is named I/O Manager in NT and IFS
......@@ -230,12 +174,7 @@ kernel support.
which does not block Venus since Venus must attend to other tasks even
when no messages are waiting or being processed.
Interfaces of the Coda FS Driver
**Interfaces of the Coda FS Driver**
Furthermore the FS layer provides for a special path of communication
between a user process and Venus, called the pioctl interface. The
......@@ -259,11 +198,9 @@ kernel support.
not go into the calls exported to the VFS layer but we will state the
requirements of the message exchange mechanism.
0wpage
33.. TThhee mmeessssaaggee llaayyeerr
3. The message layer
=====================
At the lowest level the communication between Venus and the FS driver
proceeds through messages. The synchronization between processes
......@@ -286,7 +223,7 @@ kernel support.
message. Additional platform dependent structures involve pointers to
determine the position of the message on queues and pointers to
synchronization objects. In the upcall routine the message structure
is filled in, flags are set to 0, and it is placed on the _p_e_n_d_i_n_g
is filled in, flags are set to 0, and it is placed on the *pending*
queue. The routine calling upcall is responsible for allocating the
data buffer; its structure will be described in the next section.
......@@ -312,7 +249,7 @@ kernel support.
driver looks at the contents of the message and decides if:
+o the message is a reply for a suspended thread P. If so it removes
* the message is a reply for a suspended thread P. If so it removes
the message from the processing queue and marks the message as
WRITTEN. Finally, the FS driver unblocks P (still in the kernel
mode context of Venus) and the sendmsg_to_kernel call returns to
......@@ -320,7 +257,7 @@ kernel support.
processing its upcall with the data buffer replaced with the reply
from Venus.
+o The message is a _d_o_w_n_c_a_l_l. A downcall is a request from Venus to
* The message is a ``downcall``. A downcall is a request from Venus to
the FS Driver. The FS driver processes the request immediately
(usually a cache eviction or replacement) and when it finishes
sendmsg_to_kernel returns.
......@@ -334,12 +271,7 @@ kernel support.
with its processing.
Sleeping and IPC arrangements
**Sleeping and IPC arrangements**
In case P is woken up by a signal and not by Venus, it will first look
at the flags field. If the message is not yet READ, the process P can
......@@ -355,7 +287,8 @@ kernel support.
33..11.. IImmpplleemmeennttaattiioonn ddeettaaiillss
3.1. Implementation details
----------------------------
The Unix implementation of this mechanism has been through the
implementation of a character device associated with Coda. Venus
......@@ -372,15 +305,15 @@ kernel support.
message arrival. The process P is kept waiting on a KernelEvent
object in NT and a semaphore in Windows 95.
0wpage
44.. TThhee iinntteerrffaaccee aatt tthhee ccaallll lleevveell
4. The interface at the call level
===================================
This section describes the upcalls a Coda FS driver can make to Venus.
Each of these upcalls make use of two structures: inputArgs and
outputArgs. In pseudo BNF form the structures take the following
form:
form::
struct inputArgs {
......@@ -417,7 +350,8 @@ kernel support.
44..11.. DDaattaa ssttrruuccttuurreess sshhaarreedd bbyy tthhee kkeerrnneell aanndd VVeennuuss
4.1. Data structures shared by the kernel and Venus
----------------------------------------------------
The CodaCred structure defines a variety of user and group ids as
......@@ -425,7 +359,7 @@ kernel support.
unsigned integers. It also defines group membership in an array. On
Unix the CodaCred has proven sufficient to implement good security
semantics for Coda but the structure may have to undergo modification
for the Windows environment when these mature.
for the Windows environment when these mature::
struct CodaCred {
vuid_t cr_uid, cr_euid, cr_suid, cr_fsuid; /* Real, effective, set, fs uid */
......@@ -434,19 +368,16 @@ kernel support.
};
.. Note::
NNOOTTEE It is questionable if we need CodaCreds in Venus. Finally Venus
It is questionable if we need CodaCreds in Venus. Finally Venus
doesn't know about groups, although it does create files with the
default uid/gid. Perhaps the list of group membership is superfluous.
The next item is the fundamental identifier used to identify Coda
files, the ViceFid. A fid of a file uniquely defines a file or
directory in the Coda filesystem within a _c_e_l_l. (-- A _c_e_l_l is a
group of Coda servers acting under the aegis of a single system
control machine or SCM. See the Coda Administration manual for a
detailed description of the role of the SCM.--)
directory in the Coda filesystem within a cell [1]_::
typedef struct ViceFid {
VolumeId Volume;
......@@ -454,7 +385,9 @@ kernel support.
Unique_t Unique;
} ViceFid;
.. [1] A cell is agroup of Coda servers acting under the aegis of a single
system control machine or SCM. See the Coda Administration manual
for a detailed description of the role of the SCM.
Each of the constituent fields: VolumeId, VnodeId and Unique_t are
unsigned 32 bit integers. We envisage that a further field will need
......@@ -464,21 +397,7 @@ kernel support.
The next important structure shared between Venus and the kernel is
the attributes of the file. The following structure is used to
exchange information. It has room for future extensions such as
support for device files (currently not present in Coda).
support for device files (currently not present in Coda)::
struct coda_timespec {
......@@ -509,9 +428,8 @@ kernel support.
};
44..22.. TThhee ppiiooccttll iinntteerrffaaccee
4.2. The pioctl interface
--------------------------
Coda specific requests can be made by application through the pioctl
......@@ -520,10 +438,10 @@ kernel support.
a file handle and makes the ioctl call. Finally it closes the file.
The kernel involvement in this is limited to providing the facility to
open and close and pass the ioctl message _a_n_d to verify that a path in
open and close and pass the ioctl message and to verify that a path in
the pioctl data buffers is a file in a Coda filesystem.
The kernel is handed a data packet of the form:
The kernel is handed a data packet of the form::
struct {
const char *path;
......@@ -533,7 +451,7 @@ kernel support.
where
where::
struct ViceIoctl {
......@@ -547,21 +465,22 @@ kernel support.
The path must be a Coda file, otherwise the ioctl upcall will not be
made.
NNOOTTEE The data structures and code are a mess. We need to clean this
up.
.. Note:: The data structures and code are a mess. We need to clean this up.
We now proceed to document the individual calls:
0wpage
**We now proceed to document the individual calls**:
44..33.. rroooott
4.3. root
----------
AArrgguummeennttss
iinn empty
Arguments
in
empty
oouutt
out::
struct cfs_root_out {
ViceFid VFid;
......@@ -569,24 +488,23 @@ kernel support.
DDeessccrriippttiioonn This call is made to Venus during the initialization of
Description
This call is made to Venus during the initialization of
the Coda filesystem. If the result is zero, the cfs_root structure
contains the ViceFid of the root of the Coda filesystem. If a non-zero
result is generated, its value is a platform dependent error code
indicating the difficulty Venus encountered in locating the root of
the Coda filesystem.
0wpage
4.4. lookup
------------
44..44.. llooookkuupp
Summary
Find the ViceFid and type of an object in a directory if it exists.
SSuummmmaarryy Find the ViceFid and type of an object in a directory if it
exists.
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_lookup_in {
ViceFid VFid;
......@@ -595,7 +513,7 @@ kernel support.
oouutt
out::
struct cfs_lookup_out {
ViceFid VFid;
......@@ -604,7 +522,8 @@ kernel support.
DDeessccrriippttiioonn This call is made to determine the ViceFid and filetype of
Description
This call is made to determine the ViceFid and filetype of
a directory entry. The directory entry requested carries name name
and Venus will search the directory identified by cfs_lookup_in.VFid.
The result may indicate that the name does not exist, or that
......@@ -620,19 +539,20 @@ kernel support.
cfs_lookup.vtype with CFS_NOCACHE to indicate that the object should
not be put in the kernel name cache.
NNOOTTEE The type of the vtype is currently wrong. It should be
coda_vtype. Linux does not take note of CFS_NOCACHE. It should.
.. Note::
0wpage
The type of the vtype is currently wrong. It should be
coda_vtype. Linux does not take note of CFS_NOCACHE. It should.
44..55.. ggeettaattttrr
4.5. getattr
-------------
SSuummmmaarryy Get the attributes of a file.
AArrgguummeennttss
Summary Get the attributes of a file.
iinn
Arguments
in::
struct cfs_getattr_in {
ViceFid VFid;
......@@ -641,7 +561,7 @@ kernel support.
oouutt
out::
struct cfs_getattr_out {
struct coda_vattr attr;
......@@ -649,32 +569,35 @@ kernel support.
DDeessccrriippttiioonn This call returns the attributes of the file identified by
fid.
Description
This call returns the attributes of the file identified by fid.
EErrrroorrss Errors can occur if the object with fid does not exist, is
Errors
Errors can occur if the object with fid does not exist, is
unaccessible or if the caller does not have permission to fetch
attributes.
NNoottee Many kernel FS drivers (Linux, NT and Windows 95) need to acquire
.. Note::
Many kernel FS drivers (Linux, NT and Windows 95) need to acquire
the attributes as well as the Fid for the instantiation of an internal
"inode" or "FileHandle". A significant improvement in performance on
such systems could be made by combining the _l_o_o_k_u_p and _g_e_t_a_t_t_r calls
such systems could be made by combining the lookup and getattr calls
both at the Venus/kernel interaction level and at the RPC level.
The vattr structure included in the input arguments is superfluous and
should be removed.
0wpage
44..66.. sseettaattttrr
4.6. setattr
-------------
SSuummmmaarryy Set the attributes of a file.
Summary
Set the attributes of a file.
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_setattr_in {
ViceFid VFid;
......@@ -684,29 +607,29 @@ kernel support.
oouutt
out
empty
DDeessccrriippttiioonn The structure attr is filled with attributes to be changed
Description
The structure attr is filled with attributes to be changed
in BSD style. Attributes not to be changed are set to -1, apart from
vtype which is set to VNON. Other are set to the value to be assigned.
The only attributes which the FS driver may request to change are the
mode, owner, groupid, atime, mtime and ctime. The return value
indicates success or failure.
EErrrroorrss A variety of errors can occur. The object may not exist, may
Errors
A variety of errors can occur. The object may not exist, may
be inaccessible, or permission may not be granted by Venus.
0wpage
44..77.. aacccceessss
4.7. access
------------
SSuummmmaarryy
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_access_in {
ViceFid VFid;
......@@ -715,29 +638,32 @@ kernel support.
oouutt
out
empty
DDeessccrriippttiioonn Verify if access to the object identified by VFid for
Description
Verify if access to the object identified by VFid for
operations described by flags is permitted. The result indicates if
access will be granted. It is important to remember that Coda uses
ACLs to enforce protection and that ultimately the servers, not the
clients enforce the security of the system. The result of this call
will depend on whether a _t_o_k_e_n is held by the user.
will depend on whether a token is held by the user.
EErrrroorrss The object may not exist, or the ACL describing the protection
Errors
The object may not exist, or the ACL describing the protection
may not be accessible.
0wpage
44..88.. ccrreeaattee
4.8. create
------------
SSuummmmaarryy Invoked to create a file
Summary
Invoked to create a file
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_create_in {
ViceFid VFid;
......@@ -750,7 +676,7 @@ kernel support.
oouutt
out::
struct cfs_create_out {
ViceFid VFid;
......@@ -759,7 +685,8 @@ kernel support.
DDeessccrriippttiioonn This upcall is invoked to request creation of a file.
Description
This upcall is invoked to request creation of a file.
The file will be created in the directory identified by VFid, its name
will be name, and the mode will be mode. If excl is set an error will
be returned if the file already exists. If the size field in attr is
......@@ -771,11 +698,14 @@ kernel support.
object.
EErrrroorrss A variety of errors can occur. Permissions may be insufficient.
Errors
A variety of errors can occur. Permissions may be insufficient.
If the object exists and is not a file the error EISDIR is returned
under Unix.
NNOOTTEE The packing of parameters is very inefficient and appears to
.. Note::
The packing of parameters is very inefficient and appears to
indicate confusion between the system call creat and the VFS operation
create. The VFS operation create is only called to create new objects.
This create call differs from the Unix one in that it is not invoked
......@@ -787,16 +717,16 @@ kernel support.
The attributes of the directory should be returned too, since the size
and mtime changed.
0wpage
44..99.. mmkkddiirr
4.9. mkdir
-----------
SSuummmmaarryy Create a new directory.
AArrgguummeennttss
Summary
Create a new directory.
iinn
Arguments
in::
struct cfs_mkdir_in {
ViceFid VFid;
......@@ -806,7 +736,7 @@ kernel support.
oouutt
out::
struct cfs_mkdir_out {
ViceFid VFid;
......@@ -816,29 +746,33 @@ kernel support.
DDeessccrriippttiioonn This call is similar to create but creates a directory.
Description
This call is similar to create but creates a directory.
Only the mode field in the input parameters is used for creation.
Upon successful creation, the attr returned contains the attributes of
the new directory.
EErrrroorrss As for create.
Errors
As for create.
NNOOTTEE The input parameter should be changed to mode instead of
.. Note::
The input parameter should be changed to mode instead of
attributes.
The attributes of the parent should be returned since the size and
mtime changes.
0wpage
44..1100.. lliinnkk
4.10. link
-----------
SSuummmmaarryy Create a link to an existing file.
AArrgguummeennttss
Summary
Create a link to an existing file.
iinn
Arguments
in::
struct cfs_link_in {
ViceFid sourceFid; /* cnode to link *to* */
......@@ -848,25 +782,30 @@ kernel support.
oouutt
out
empty
DDeessccrriippttiioonn This call creates a link to the sourceFid in the directory
Description
This call creates a link to the sourceFid in the directory
identified by destFid with name tname. The source must reside in the
target's parent, i.e. the source must be have parent destFid, i.e. Coda
does not support cross directory hard links. Only the return value is
relevant. It indicates success or the type of failure.
EErrrroorrss The usual errors can occur.0wpage
Errors
The usual errors can occur.
44..1111.. ssyymmlliinnkk
4.11. symlink
--------------
SSuummmmaarryy create a symbolic link
AArrgguummeennttss
Summary
create a symbolic link
iinn
Arguments
in::
struct cfs_symlink_in {
ViceFid VFid; /* Directory to put symlink in */
......@@ -877,29 +816,31 @@ kernel support.
oouutt
out
none
DDeessccrriippttiioonn Create a symbolic link. The link is to be placed in the
Description
Create a symbolic link. The link is to be placed in the
directory identified by VFid and named tname. It should point to the
pathname srcname. The attributes of the newly created object are to
be set to attr.
EErrrroorrss
.. Note::
NNOOTTEE The attributes of the target directory should be returned since
The attributes of the target directory should be returned since
its size changed.
0wpage
44..1122.. rreemmoovvee
4.12. remove
-------------
SSuummmmaarryy Remove a file
AArrgguummeennttss
Summary
Remove a file
iinn
Arguments
in::
struct cfs_remove_in {
ViceFid VFid;
......@@ -908,27 +849,30 @@ kernel support.
oouutt
out
none
DDeessccrriippttiioonn Remove file named cfs_remove_in.name in directory
Description
Remove file named cfs_remove_in.name in directory
identified by VFid.
EErrrroorrss
NNOOTTEE The attributes of the directory should be returned since its
mtime and size may change.
.. Note::
0wpage
The attributes of the directory should be returned since its
mtime and size may change.
44..1133.. rrmmddiirr
4.13. rmdir
------------
SSuummmmaarryy Remove a directory
AArrgguummeennttss
Summary
Remove a directory
iinn
Arguments
in::
struct cfs_rmdir_in {
ViceFid VFid;
......@@ -937,27 +881,27 @@ kernel support.
oouutt
out
none
DDeessccrriippttiioonn Remove the directory with name name from the directory
Description
Remove the directory with name name from the directory
identified by VFid.
EErrrroorrss
NNOOTTEE The attributes of the parent directory should be returned since
.. Note:: The attributes of the parent directory should be returned since
its mtime and size may change.
0wpage
44..1144.. rreeaaddlliinnkk
4.14. readlink
---------------
SSuummmmaarryy Read the value of a symbolic link.
Summary
Read the value of a symbolic link.
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_readlink_in {
ViceFid VFid;
......@@ -965,7 +909,7 @@ kernel support.
oouutt
out::
struct cfs_readlink_out {
int count;
......@@ -974,22 +918,24 @@ kernel support.
DDeessccrriippttiioonn This routine reads the contents of symbolic link
Description
This routine reads the contents of symbolic link
identified by VFid into the buffer data. The buffer data must be able
to hold any name up to CFS_MAXNAMLEN (PATH or NAM??).
EErrrroorrss No unusual errors.
0wpage
Errors
No unusual errors.
44..1155.. ooppeenn
4.15. open
-----------
SSuummmmaarryy Open a file.
AArrgguummeennttss
Summary
Open a file.
iinn
Arguments
in::
struct cfs_open_in {
ViceFid VFid;
......@@ -998,7 +944,7 @@ kernel support.
oouutt
out::
struct cfs_open_out {
dev_t dev;
......@@ -1007,30 +953,33 @@ kernel support.
DDeessccrriippttiioonn This request asks Venus to place the file identified by
Description
This request asks Venus to place the file identified by
VFid in its cache and to note that the calling process wishes to open
it with flags as in open(2). The return value to the kernel differs
for Unix and Windows systems. For Unix systems the Coda FS Driver is
informed of the device and inode number of the container file in the
fields dev and inode. For Windows the path of the container file is
returned to the kernel.
EErrrroorrss
NNOOTTEE Currently the cfs_open_out structure is not properly adapted to
.. Note::
Currently the cfs_open_out structure is not properly adapted to
deal with the Windows case. It might be best to implement two
upcalls, one to open aiming at a container file name, the other at a
container file inode.
0wpage
44..1166.. cclloossee
4.16. close
------------
SSuummmmaarryy Close a file, update it on the servers.
AArrgguummeennttss
Summary
Close a file, update it on the servers.
iinn
Arguments
in::
struct cfs_close_in {
ViceFid VFid;
......@@ -1039,14 +988,16 @@ kernel support.
oouutt
out
none
DDeessccrriippttiioonn Close the file identified by VFid.
Description
Close the file identified by VFid.
EErrrroorrss
.. Note::
NNOOTTEE The flags argument is bogus and not used. However, Venus' code
The flags argument is bogus and not used. However, Venus' code
has room to deal with an execp input field, probably this field should
be used to inform Venus that the file was closed but is still memory
mapped for execution. There are comments about fetching versus not
......@@ -1056,16 +1007,16 @@ kernel support.
currently Venus might think a file can be flushed from the cache when
it is still memory mapped. This needs to be understood.
0wpage
44..1177.. iiooccttll
4.17. ioctl
------------
SSuummmmaarryy Do an ioctl on a file. This includes the pioctl interface.
AArrgguummeennttss
Summary
Do an ioctl on a file. This includes the pioctl interface.
iinn
Arguments
in::
struct cfs_ioctl_in {
ViceFid VFid;
......@@ -1077,7 +1028,7 @@ kernel support.
oouutt
out::
struct cfs_ioctl_out {
......@@ -1087,25 +1038,26 @@ kernel support.
DDeessccrriippttiioonn Do an ioctl operation on a file. The command, len and
Description
Do an ioctl operation on a file. The command, len and
data arguments are filled as usual. flags is not used by Venus.
EErrrroorrss
.. Note::
NNOOTTEE Another bogus parameter. flags is not used. What is the
Another bogus parameter. flags is not used. What is the
business about PREFETCHING in the Venus code?
0wpage
44..1188.. rreennaammee
4.18. rename
-------------
SSuummmmaarryy Rename a fid.
Summary
Rename a fid.
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_rename_in {
ViceFid sourceFid;
......@@ -1116,26 +1068,26 @@ kernel support.
oouutt
out
none
DDeessccrriippttiioonn Rename the object with name srcname in directory
Description
Rename the object with name srcname in directory
sourceFid to destname in destFid. It is important that the names
srcname and destname are 0 terminated strings. Strings in Unix
kernels are not always null terminated.
EErrrroorrss
0wpage
44..1199.. rreeaaddddiirr
4.19. readdir
--------------
SSuummmmaarryy Read directory entries.
Summary
Read directory entries.
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_readdir_in {
ViceFid VFid;
......@@ -1146,7 +1098,7 @@ kernel support.
oouutt
out::
struct cfs_readdir_out {
int size;
......@@ -1155,26 +1107,28 @@ kernel support.
DDeessccrriippttiioonn Read directory entries from VFid starting at offset and
Description
Read directory entries from VFid starting at offset and
read at most count bytes. Returns the data in data and returns
the size in size.
EErrrroorrss
NNOOTTEE This call is not used. Readdir operations exploit container
.. Note::
This call is not used. Readdir operations exploit container
files. We will re-evaluate this during the directory revamp which is
about to take place.
0wpage
44..2200.. vvggeett
4.20. vget
-----------
SSuummmmaarryy instructs Venus to do an FSDB->Get.
Summary
instructs Venus to do an FSDB->Get.
AArrgguummeennttss
iinn
Arguments
in::
struct cfs_vget_in {
ViceFid VFid;
......@@ -1182,7 +1136,7 @@ kernel support.
oouutt
out::
struct cfs_vget_out {
ViceFid VFid;
......@@ -1191,26 +1145,27 @@ kernel support.
DDeessccrriippttiioonn This upcall asks Venus to do a get operation on an fsobj
Description
This upcall asks Venus to do a get operation on an fsobj
labelled by VFid.
EErrrroorrss
.. Note::
NNOOTTEE This operation is not used. However, it is extremely useful
This operation is not used. However, it is extremely useful
since it can be used to deal with read/write memory mapped files.
These can be "pinned" in the Venus cache using vget and released with
inactive.
0wpage
44..2211.. ffssyynncc
4.21. fsync
------------
SSuummmmaarryy Tell Venus to update the RVM attributes of a file.
AArrgguummeennttss
Summary
Tell Venus to update the RVM attributes of a file.
iinn
Arguments
in::
struct cfs_fsync_in {
ViceFid VFid;
......@@ -1218,27 +1173,27 @@ kernel support.
oouutt
out
none
DDeessccrriippttiioonn Ask Venus to update RVM attributes of object VFid. This
Description
Ask Venus to update RVM attributes of object VFid. This
should be called as part of kernel level fsync type calls. The
result indicates if the syncing was successful.
EErrrroorrss
NNOOTTEE Linux does not implement this call. It should.
0wpage
.. Note:: Linux does not implement this call. It should.
44..2222.. iinnaaccttiivvee
4.22. inactive
---------------
SSuummmmaarryy Tell Venus a vnode is no longer in use.
AArrgguummeennttss
Summary
Tell Venus a vnode is no longer in use.
iinn
Arguments
in::
struct cfs_inactive_in {
ViceFid VFid;
......@@ -1246,25 +1201,25 @@ kernel support.
oouutt
none
DDeessccrriippttiioonn This operation returns EOPNOTSUPP.
out
EErrrroorrss
none
NNOOTTEE This should perhaps be removed.
Description
This operation returns EOPNOTSUPP.
0wpage
.. Note:: This should perhaps be removed.
44..2233.. rrddwwrr
4.23. rdwr
-----------
SSuummmmaarryy Read or write from a file
AArrgguummeennttss
Summary
Read or write from a file
iinn
Arguments
in::
struct cfs_rdwr_in {
ViceFid VFid;
......@@ -1278,7 +1233,7 @@ kernel support.
oouutt
out::
struct cfs_rdwr_out {
int rwflag;
......@@ -1288,26 +1243,27 @@ kernel support.
DDeessccrriippttiioonn This upcall asks Venus to read or write from a file.
Description
This upcall asks Venus to read or write from a file.
EErrrroorrss
NNOOTTEE It should be removed since it is against the Coda philosophy that
.. Note::
It should be removed since it is against the Coda philosophy that
read/write operations never reach Venus. I have been told the
operation does not work. It is not currently used.
0wpage
44..2244.. ooddyymmoouunntt
4.24. odymount
---------------
SSuummmmaarryy Allows mounting multiple Coda "filesystems" on one Unix mount
point.
AArrgguummeennttss
Summary
Allows mounting multiple Coda "filesystems" on one Unix mount point.
iinn
Arguments
in::
struct ody_mount_in {
char *name; /* Place holder for data. */
......@@ -1315,7 +1271,7 @@ kernel support.
oouutt
out::
struct ody_mount_out {
ViceFid VFid;
......@@ -1323,110 +1279,121 @@ kernel support.
DDeessccrriippttiioonn Asks Venus to return the rootfid of a Coda system named
Description
Asks Venus to return the rootfid of a Coda system named
name. The fid is returned in VFid.
EErrrroorrss
.. Note::
NNOOTTEE This call was used by David for dynamic sets. It should be
This call was used by David for dynamic sets. It should be
removed since it causes a jungle of pointers in the VFS mounting area.
It is not used by Coda proper. Call is not implemented by Venus.
0wpage
44..2255.. ooddyy__llooookkuupp
4.25. ody_lookup
-----------------
SSuummmmaarryy Looks up something.
Summary
Looks up something.
AArrgguummeennttss
Arguments
in
irrelevant
iinn irrelevant
out
oouutt
irrelevant
DDeessccrriippttiioonn
EErrrroorrss
.. Note:: Gut it. Call is not implemented by Venus.
NNOOTTEE Gut it. Call is not implemented by Venus.
0wpage
4.26. ody_expand
-----------------
44..2266.. ooddyy__eexxppaanndd
Summary
expands something in a dynamic set.
SSuummmmaarryy expands something in a dynamic set.
Arguments
in
AArrgguummeennttss
irrelevant
iinn irrelevant
out
oouutt
irrelevant
DDeessccrriippttiioonn
.. Note:: Gut it. Call is not implemented by Venus.
EErrrroorrss
NNOOTTEE Gut it. Call is not implemented by Venus.
4.27. prefetch
---------------
0wpage
44..2277.. pprreeffeettcchh
Summary
Prefetch a dynamic set.
Arguments
SSuummmmaarryy Prefetch a dynamic set.
in
AArrgguummeennttss
Not documented.
iinn Not documented.
out
oouutt
Not documented.
DDeessccrriippttiioonn Venus worker.cc has support for this call, although it is
Description
Venus worker.cc has support for this call, although it is
noted that it doesn't work. Not surprising, since the kernel does not
have support for it. (ODY_PREFETCH is not a defined operation).
EErrrroorrss
NNOOTTEE Gut it. It isn't working and isn't used by Coda.
.. Note:: Gut it. It isn't working and isn't used by Coda.
0wpage
4.28. signal
-------------
44..2288.. ssiiggnnaall
Summary
Send Venus a signal about an upcall.
SSuummmmaarryy Send Venus a signal about an upcall.
Arguments
in
AArrgguummeennttss
none
iinn none
out
oouutt
not applicable.
DDeessccrriippttiioonn This is an out-of-band upcall to Venus to inform Venus
Description
This is an out-of-band upcall to Venus to inform Venus
that the calling process received a signal after Venus read the
message from the input queue. Venus is supposed to clean up the
operation.
EErrrroorrss No reply is given.
Errors
No reply is given.
.. Note::
NNOOTTEE We need to better understand what Venus needs to clean up and if
We need to better understand what Venus needs to clean up and if
it is doing this correctly. Also we need to handle multiple upcall
per system call situations correctly. It would be important to know
what state changes in Venus take place after an upcall for which the
kernel is responsible for notifying Venus to clean up (e.g. open
definitely is such a state change, but many others are maybe not).
0wpage
55.. TThhee mmiinniiccaacchhee aanndd ddoowwnnccaallllss
5. The minicache and downcalls
===============================
The Coda FS Driver can cache results of lookup and access upcalls, to
......@@ -1440,7 +1407,7 @@ kernel support.
FileHandles in Windows) with the ViceFid's which Venus maintains. The
reason is that frequent translations back and forth are needed in
order to make upcalls and use the results of upcalls. Such linking
objects are called ccnnooddeess.
objects are called cnodes.
The current minicache implementations have cache entries which record
the following:
......@@ -1466,30 +1433,37 @@ kernel support.
unless the downcall data could not be read into kernel memory.
55..11.. IINNVVAALLIIDDAATTEE
5.1. INVALIDATE
----------------
No information is available on this call.
55..22.. FFLLUUSSHH
5.2. FLUSH
-----------
AArrgguummeennttss None
Arguments
None
SSuummmmaarryy Flush the name cache entirely.
Summary
Flush the name cache entirely.
DDeessccrriippttiioonn Venus issues this call upon startup and when it dies. This
Description
Venus issues this call upon startup and when it dies. This
is to prevent stale cache information being held. Some operating
systems allow the kernel name cache to be switched off dynamically.
When this is done, this downcall is made.
55..33.. PPUURRGGEEUUSSEERR
5.3. PURGEUSER
---------------
AArrgguummeennttss
Arguments
::
struct cfs_purgeuser_out {/* CFS_PURGEUSER is a venus->kernel call */
struct CodaCred cred;
......@@ -1497,14 +1471,17 @@ kernel support.
DDeessccrriippttiioonn Remove all entries in the cache carrying the Cred. This
Description
Remove all entries in the cache carrying the Cred. This
call is issued when tokens for a user expire or are flushed.
55..44.. ZZAAPPFFIILLEE
5.4. ZAPFILE
-------------
AArrgguummeennttss
Arguments
::
struct cfs_zapfile_out { /* CFS_ZAPFILE is a venus->kernel call */
ViceFid CodaFid;
......@@ -1512,20 +1489,25 @@ kernel support.
DDeessccrriippttiioonn Remove all entries which have the (dir vnode, name) pair.
Description
Remove all entries which have the (dir vnode, name) pair.
This is issued as a result of an invalidation of cached attributes of
a vnode.
NNOOTTEE Call is not named correctly in NetBSD and Mach. The minicache
.. Note::
Call is not named correctly in NetBSD and Mach. The minicache
zapfile routine takes different arguments. Linux does not implement
the invalidation of attributes correctly.
55..55.. ZZAAPPDDIIRR
5.5. ZAPDIR
------------
AArrgguummeennttss
Arguments
::
struct cfs_zapdir_out { /* CFS_ZAPDIR is a venus->kernel call */
ViceFid CodaFid;
......@@ -1533,16 +1515,19 @@ kernel support.
DDeessccrriippttiioonn Remove all entries in the cache lying in a directory
Description
Remove all entries in the cache lying in a directory
CodaFid, and all children of this directory. This call is issued when
Venus receives a callback on the directory.
55..66.. ZZAAPPVVNNOODDEE
5.6. ZAPVNODE
--------------
AArrgguummeennttss
Arguments
::
struct cfs_zapvnode_out { /* CFS_ZAPVNODE is a venus->kernel call */
struct CodaCred cred;
......@@ -1551,16 +1536,17 @@ kernel support.
DDeessccrriippttiioonn Remove all entries in the cache carrying the cred and VFid
Description
Remove all entries in the cache carrying the cred and VFid
as in the arguments. This downcall is probably never issued.
55..77.. PPUURRGGEEFFIIDD
5.7. PURGEFID
--------------
SSuummmmaarryy
AArrgguummeennttss
Arguments
::
struct cfs_purgefid_out { /* CFS_PURGEFID is a venus->kernel call */
ViceFid CodaFid;
......@@ -1568,18 +1554,22 @@ kernel support.
DDeessccrriippttiioonn Flush the attribute for the file. If it is a dir (odd
Description
Flush the attribute for the file. If it is a dir (odd
vnode), purge its children from the namecache and remove the file from the
namecache.
55..88.. RREEPPLLAACCEE
5.8. REPLACE
-------------
SSuummmmaarryy Replace the Fid's for a collection of names.
Summary
Replace the Fid's for a collection of names.
AArrgguummeennttss
Arguments
::
struct cfs_replace_out { /* cfs_replace is a venus->kernel call */
ViceFid NewFid;
......@@ -1588,14 +1578,15 @@ kernel support.
DDeessccrriippttiioonn This routine replaces a ViceFid in the name cache with
Description
This routine replaces a ViceFid in the name cache with
another. It is added to allow Venus during reintegration to replace
locally allocated temp fids while disconnected with global fids even
when the reference counts on those fids are not zero.
0wpage
66.. IInniittiiaalliizzaattiioonn aanndd cclleeaannuupp
6. Initialization and cleanup
==============================
This section gives brief hints as to desirable features for the Coda
......@@ -1624,11 +1615,12 @@ kernel support.
3. pioctl interface
Currently the _p_i_o_c_t_l passes through the VFS for Coda so we can
Currently the pioctl passes through the VFS for Coda so we can
treat these similarly.
66..11.. RReeqquuiirreemmeennttss
6.1. Requirements
------------------
The following requirements should be accommodated:
......@@ -1636,14 +1628,14 @@ kernel support.
1. The message queues should have open and close routines. On Unix
the opening of the character devices are such routines.
+o Before opening, no messages can be placed.
- Before opening, no messages can be placed.
+o Opening will remove any old messages still pending.
- Opening will remove any old messages still pending.
+o Close will notify any sleeping processes that their upcall cannot
- Close will notify any sleeping processes that their upcall cannot
be completed.
+o Close will free all memory allocated by the message queues.
- Close will free all memory allocated by the message queues.
2. At open the namecache shall be initialized to empty state.
......@@ -1668,7 +1660,9 @@ kernel support.
best implemented by Venus fetching these objects before attempting
to mount.
NNOOTTEE NetBSD in particular but also Linux have not implemented the
.. Note::
NetBSD in particular but also Linux have not implemented the
above requirements fully. For smooth operation this needs to be
corrected.
......
Documentation/filesystems/index.rst
View file @ f476c6ed
......@@ -63,6 +63,7 @@ Documentation for filesystem implementations.
btrfs
cifs/cifsroot
ceph
coda
cramfs
debugfs
dlmfs
......
MAINTAINERS
View file @ f476c6ed
......@@ -4203,7 +4203,7 @@ M: coda@cs.cmu.edu
L: codalist@coda.cs.cmu.edu
S: Maintained
W: http://www.coda.cs.cmu.edu/
F: Documentation/filesystems/coda.txt
F: Documentation/filesystems/coda.rst
F: fs/coda/
F: include/linux/coda*.h
F: include/uapi/linux/coda*.h
......
fs/coda/Kconfig
View file @ f476c6ed
......@@ -15,7 +15,7 @@ config CODA_FS
*client*. You will need user level code as well, both for the
client and server. Servers are currently user level, i.e. they need
no kernel support. Please read
<file:Documentation/filesystems/coda.txt> and check out the Coda
<file:Documentation/filesystems/coda.rst> and check out the Coda
home page <http://www.coda.cs.cmu.edu/>.
To compile the coda client support as a module, choose M here: the
......
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