Function

The vn_close operation closes a file or socket.

Environment on entry and exit

See Environment for PFS operations.

Parameters

Token_structure

Supplied parameter

Type:

TOKSTR

Length:

Specified by TOKSTR.ts_hdr.cblen.

The Token_structure represents the file (vnode) that is being operated on. It contains the PFS's initialization token, mount token, and the file token. Refer to LFS/PFS control block structure for a discussion of this structure, and to the TOKSTR typedef in BPXYPFSI in Interface structures for C language servers and clients for its mapping.

OSI_structure

Supplied and returned parameter

Type:

OSI

Length:

Specified by OSI.osi_hdr.cblen.

The OSI_structure contains information that is used by the OSI operations that may be called by the PFS. See OSI services for more information.

It also contains MVS-specific information that needs to be passed to the PFS, including SMF accounting fields, a work area, a recovery area, and an optional pointer to an output ATTR structure. For more details on the OSI structure, see The OSI structure.

This area is mapped by the OSI typedef in BPXYPFSI in Interface structures for C language servers and clients.

Audit_structure

Supplied parameter

Type:

CRED

Length:

Specified by CRED.cred_hdr.cblen.

The Audit_structure contains information that is used by the security product for access checks and auditing. It is passed to most SAF routines that are invoked by the PFS.

Refer to Security responsibilities and considerations for a discussion of security processing, and to the CRED typedef in BPXYPFSI in Interface structures for C language servers and clients for the mapping of this structure.

Open_flags

Supplied parameter

Type:

Bit

Length:

Fullword

A fullword containing the open flags that are associated with this file. These flags are defined by fcntl.h.

Return_value

Returned parameter

Type:

Integer

Length:

Fullword

A fullword in which the vn_close operation returns the results of the operation, as one of the following:

Return_value

Meaning

-1

The operation was not successful. The Return_code and Reason_Code values must be filled in by the PFS when Return_value is -1.

0

The operation was successful.

Return_code

Returned parameter

Type:

Integer

Length:

Fullword

A fullword in which the vn_close operation stores the return code. The vn_close operation returns Return_code only if Return_value is -1. See z/OS UNIX System Services Messages and Codes for a complete list of supported return code values.

Reason_code

Returned parameter

Type:

Integer

Length:

Fullword

A fullword in which the vn_close operation stores the reason code. The vn_close operation returns Reason_code only if Return_value is -1. Reason_code further qualifies the Return_code value. These reason codes are documented by the PFS.

Implementation notes

Overview of vn_close processing

See Opening and closing files and first references to files for a discussion of close processing.

See Creating, referring to, and closing socket vnodes for a discussion of relevant socket processing.

For more information about the semantics of this operation for a POSIX-conforming PFS, refer to the close() function in the POSIX .1 standard (IEEE Std 1003.1-1990).

Specific processing notes

1. The Return_value parameter is preset to -1 before the PFS is called. If the PFS program checks or ends abnormally during the vn_close operation and the abend is percolated back to the LFS, the LFS uses the Return_value to determine what to do next. If the Return_value is still -1, the PFS is recalled with vn_close; otherwise it is not. Therefore, just before the PFS reaches a point at which it would rather not be recalled if it should end abnormally, it should zero out the Return_value.
2. If the PFS supports vn_recovery, and vn_recovery returns control information to direct the outcome of the original call, the rule is overridden. That is, vn_close is not recalled if it appears that vn_recovery has handled the problem, regardless of the value of Return_value.
3. Although the Return_value, Return_code, and Reason_code values are returned to the caller, the operation always succeeds in that the user's file descriptor is freed and the vnode's open counter is decremented, regardless of the Return_value.
4. If vn_inactive is not supported by the PFS, the LFS will free its vnode after the vn_close returns. If vn_inactive is supported, the LFS keeps the vnode for a few minutes and then invokes vn_inactive, at which time the vnode is freed.

   For sockets PFSs, the total number of vnodes in use is used to enforce the MAXSOCKETS limit. Thus, for sockets PFSs that use vn_inactive, it is possible for a heavily loaded system to reach its MAXSOCKETS limit—even though not that many sockets are open—because of closed vnodes that have not yet been inactivated.

   Refer to Creating, referring to, and closing socket vnodes for more information about socket close and inactivation.

Serialization provided by the LFS

The vn_close operation is invoked with an exclusive latch held on the vnode of the file. Shared read support for the file that is being closed can be modified in the OSI by the PFS upon returning from the vn_close operation.

Security calls to be made by the PFS

None.

Related services

• vn_open — Open a file
• vfs_socket — Create a socket or a socket pair