GPFS: Administration and Programming Reference - IRA Home

Parameters
fileDesc The file descriptor identifying the file to which GPFS applies the hints and directives.
fcntlArgP A pointer to the list of operations to be passed to GPFS.
Exit status
If the gpfs_fcntl() subroutine is successful, it returns a value of 0.
If the gpfs_fcntl() subroutine is unsuccessful, it returns a value of -1 and sets the global error variable
errno to indicate the nature of the error.
Exceptions
None.
Error status
EBADF The file descriptor is not valid.
EINVAL The file descriptor does not refer to a GPFS file or a regular file.
The system call is not valid.
ENOSYS The gpfs_fcntl() subroutine is not supported under the current file system format.
E2BIG An argument is longer than GPFS_MAX_FCNTL_LENGTH.
Examples
1. This programming segment releases all cache data held by the file handle and tell GPFS that the
subroutine will write the portion of the file with file offsets between 2 GB and 3 GB minus one:
struct
{
gpfsFcntlHeader_t hdr;
gpfsClearFileCache_t rel;
gpfsAccessRange_t acc;
} arg;
arg.hdr.totalLength = sizeof(arg);
arg.hdr.fcntlVersion = GPFS_FCNTL_CURRENT_VERSION;
arg.hdr.fcntlReserved = 0;
arg.rel.structLen = sizeof(arg.rel);
arg.rel.structType = GPFS_CLEAR_FILE_CACHE;
arg.acc.structLen = sizeof(arg.acc);
arg.acc.structType = GPFS_ACCESS_RANGE;
arg.acc.start = 2LL * 1024LL * 1024LL * 1024LL;
arg.acc.length = 1024 * 1024 * 1024;
arg.acc.isWrite = 1;
rc = gpfs_fcntl(handle, &arg);
2. This programming segment gets the storage pool name and fileset name of a file from GPFS.
struct {
gpfsFcntlHeader_t hdr;
gpfsGetStoragePool_t pool;
gpfsGetFilesetName_t fileset;
} fcntlArg;
fcntlArg.hdr.totalLength = sizeof(fcntlArg.hdr) + sizeof(fcntlArg.pool) + sizeof(fcntlArg.fileset);
fcntlArg.hdr.fcntlVersion = GPFS_FCNTL_CURRENT_VERSION;
fcntlArg.hdr.fcntlReserved = 0;
fcntlArg.pool.structLen = sizeof(fcntlArg.pool);
gpfs_fcntl() Subroutine
Chapter 9. GPFS programming interfaces 285