The OSI structure

The second parameter of every call from the LFS to the PFS is the address of the operating system interface (OSI) structure. This structure contains information that is used by the OSI_operations and MVS-specific information that needs to be passed between the LFS and the PFS. It is mapped by the OSI typedef in Interface structures for C language servers and clients. The fields are described as follows:

Field

Description

Wait-post fields

token

Wait-post token. Set by osi_wait when it is called to set up for a wait. This token is the input to osi_post when it is called to wake up the current thread.

ecb

Address of an event control block (ECB). Set by osi_wait when it is called to set up for a wait. This is the ECB that is used by osi_wait when it is called to suspend. A program that cannot call osi_post can use this ECB with an MVS™ cross-memory post to wake up the current thread. However, using the MVS cross-memory post for this ECB can result in a system integrity problem.

ascb

Address of the address space control block (ASCB). Set by osi_wait when it is called to set up for a wait. This ASCB address is used, along with the ECB, for an MVS cross-memory post.

SMF accounting fields

diribc

Directory I/O block count that occurred on this operation.

readibc

Read I/O block count that occurred on this operation.

writeibc

Write I/O block count that occurred on this operation.

bytesrd

The number of bytes that were read on this operation.

byteswr

The number of bytes that were written on this operation.

Miscellaneous fields

rtokptr

Address of the recovery token area. The recovery token area is set and cleared by the PFS on each operation, to provide for abnormal end and end-of-memory recovery. Refer to Recovery considerations for details.

workarea

Address of a work area for use by the PFS. This area can be used for the dynamic, or automatic, storage necessary to run the current operation. This can save the PFS the overhead of obtaining and freeing stack storage on every call. The workarea is on a doubleword boundary.

workarealen

Length of the workarea. The workarea length is 3KB. This allows 2KB for routines that call the SAF Chk_Owner_Two_Files routine or the osi_uiomove service, each of which requires that a 2-KB work area be passed. The other SAF security routines require a 1-KB work area.

pid

The current thread's process ID (PID). This is the input to osi_signal if it is called to send a signal to the current thread's process.

pfsid

A PFS identifier that is used with osi_sleep and osi_wakeup.

attr

Address of an output file attribute buffer. Whenever this field is nonzero, the PFS should build and return a standard attribute structure for the file operated on at the end of the current operation. This is the same attribute structure that would be returned by vn_getattr.

The buffer is preset with an attribute structure header that contains the available length of the buffer.

Because this buffer may be the same area as an input attribute structure, it should not be modified until the very end of the current operation.

If the PFS does not return the file's attributes when asked, the LFS invokes vn_getattr to get them. This results in poorer performance for files that are supported by this PFS.

fsp

Address of an output File Security Packet (FSP). Whenever this field is nonzero, the PFS should return an fsp structure for the file operated on. This is the same fsp structure that would be returned by vn_getattr.

If the PFS does not return the file's FSP when asked, the LFS builds one. For a description of the FSP, refer to Security responsibilities and considerations.

remount

A flag that indicates that the current operation is running during a remount (that is, during UNMOUNT with the REMOUNT option).

NotSigReg

Indicates that the calling process is not registered for signals and so should not be sent any.