vfs_vget — Convert a file identifier to a vnode Token

Function

The vfs_vget operation returns a vnode token for the file or directory that is represented by the input file identifier (FID).

Environment on entry and exit

See Environment for PFS operations.

Input parameter format

vfs_vget    (Token_structure,
             OSI_structure,
             Audit_structure,
             File_identifier,
             Vnode_token,
             Return_value,
             Return_code,
             Reason_code)

Parameters

Token_structure

Supplied parameter

Type:: TOKSTR
Length:: Specified by TOKSTR.ts_hdr.cblen.

The Token_structure represents the file system (VFS) that is being operated on. It contains the PFS's initialization token and mount 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.

File_identifier

Supplied parameter

Type:: FID
Length:: 8 bytes

The name of an 8-byte area containing the file identifier of the file or directory for which a vnode token is to be returned. This area is mapped by the FID typedef in the BPXYVFSI header file (see Interface structures for C language servers and clients).

Vnode_token

Returned parameter

Type:: Token
Length:: 8 bytes

Vnode_token is used to return the vnode token that corresponds to the input FID.

Return_value

Returned parameter

Type:: Integer
Length:: Fullword

The name of a fullword in which the vfs_vget service returns the results of the operation, as one of the following:

Return_value: Meaning
-1: The operation was not successful. This causes the vfs_vget request to fail. The Return_code and Reason_Code are returned to the caller.
0: The operation was successful.

Return_code

Returned parameter

Type:: Integer
Length:: Fullword

The name of a fullword in which the vfs_vget service stores the return code. The vfs_vget service returns Return_code only if Return_value is -1. For a complete list of supported return code values, see z/OS UNIX System Services Messages and Codes.

The vfs_vget service should support at least the following error values:

Return_code	Explanation
ENOENT	The file indicated by the File_identifier does not exist in the mounted file system that is indicated by token_structure
EIO	An input/output error occurred while attempting to access data pertaining to the file indicated by the File_identifier.

Reason_code

Returned parameter

Type:: Integer
Length:: Fullword

The name of a fullword in which the vfs_vget service stores the reason code. The vfs_vget service 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 vfs_vget processing
Given a file identifier as input, vfs_vget returns a vnode token that refers to the file. The file identifier uniquely identifies a file in a particular mounted file system. Its validity persists across mounting and unmounting of the file system, as well as z/OS UNIX re-IPLS. This distinguishes the file identifier from the vnode token, which relates to a file in active use, and whose validity persists only until the token is released via vn_inactive. The FID for a file is created by the PFS and returned in the ATTR structure, which is mapped by typedef ATTR in the BPXYVFSI header file (see Interface structures for C language servers and clients) by vn_getattr.
Specific processing notes
File identifier zero is taken to refer to the root of the mounted file system.
Serialization provided by the LFS
The vfs_vget operation is invoked with a shared latch held on the mounted file system.
Security calls to be made by the PFS: None.

Related services

vn_getattr — Get the attributes of a file