GPFS: Administration and Programming Reference - IRA Home

gpfs_fcntl() Subroutine
Name
gpfs_fcntl() – Performs operations on an open file.
Library
GPFS Library (libgpfs.a for AIX, libgpfs.so for Linux)
Synopsis
#include
int gpfs_fcntl(int fileDesc, void* fcntlArgP)
Description
The gpfs_fcntl() subroutine is used to pass file access pattern information and to control certain file
attributes on behalf of an open file. More than one operation can be requested with a single invocation of
gpfs_fcntl(). The type and number of operations is determined by the second operand, fcntlArgP, which
is a pointer to a data structure built in memory by the application. This data structure consists of:
v A fixed length header, mapped by gpfsFcntlHeader_t.
v A variable list of individual file access hints, directives or other control structures:
– File access hints:
1. gpfsAccessRange_t
2. gpfsFreeRange_t
3. gpfsMultipleAccessRange_t
4. gpfsClearFileCache_t
– File access directives:
1. gpfsCancelHints_t
2. gpfsDataShipMap_t
3. gpfsDataShipStart_t
4. gpfsDataShipStop_t
– Other file attribute operations:
1. gpfsGetFilesetName_t
2. gpfsGetReplication_t
3. gpfsGetSnapshotName_t
4. gpfsGetStoragePool_t
5. gpfsRestripeData_t
6. gpfsSetReplication_t
7. gpfsSetStoragePool_t
The above hints, directives and other operations may be mixed within a single gpfs_fcntl() subroutine,
and are performed in the order that they appear. A subsequent hint or directive may cancel out a
preceding one. See Chapter 7, “Communicating file access patterns to GPFS,” on page 57.
Notes:
1. Compile any program that uses this subroutine with the -lgpfs flag from the following library:
v libgpfs.a for AIX
v libgpfs.so for Linux
284 GPFS: Administration and Programming Reference