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AIX Version 4.3 Kernel and Subsystems Technical Reference, Volume 1

vn_map_lloff Entry Point

Purpose

Announces intention to map a file.

Syntax

int
vn_map_lloff (vp, addr, offset, length, mflags, fflags, crp)
struct vnode *vp;
caddr_t addr;
offset_t offset;
offset_t length;
int mflags;
int fflags;
struct ucred *crp;

Parameters

vp Points to the vnode to be queried.
addr Unused.
offset Specifies the starting offset for the map request.
length Specifies the length of the mapping request.
mflags Specifies the mapping flags.
fflags Specifies the file flags.
crp Specifies user's credentials.

Description

The vn_map_lloff entry point is used to tell the file system that the file is going to be accessed by memory mapped loads and stores. The file system should fail the request if it does not support memory mapping. This interface allows applications to specify starting offsets that are larger than 2 gigabytes.

File systems that do not define GFS_VERSION421 in their gfs flags do not need to supply a vn_map_lloff entry point.

Execution Environment

The vn_map_lloff entry point can be called from the process environment only.

Return Values

Zero Indicates a successful operation.
Nonzero Indicates that the operation failed; return values should be chosen from the /usr/include/sys/errno.h file.

Related Information

The shmat and mmap subroutines.

Virtual File System Overview, Logical File System Overview, Understanding Virtual Nodes (V-nodes), and Virtual File System Kernel Extensions Overview.

List of Virtual File System Operations.

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