path: root/src/H5FDfphdf5.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by the Board of Trustees of the University of Illinois.         *
 * All rights reserved.                                                      *
 *                                                                           *
 * This file is part of HDF5.  The full HDF5 copyright notice, including     *
 * terms governing use, modification, and redistribution, is contained in    *
 * the files COPYING and Copyright.html.  COPYING can be found at the root   *
 * of the source code distribution tree; Copyright.html can be found at the  *
 * root level of an installed copy of the electronic HDF5 document set and   *
 * is linked from the top-level documents page.  It can also be found at     *
 * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html.  If you do not have     *
 * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/* Interface initialization */
#define H5_INTERFACE_INIT_FUNC	H5FD_fphdf5_init_interface


#include "H5private.h"		/* Generic Functions			*/
#include "H5ACprivate.h"	/* Metadata cache			*/
#include "H5Dprivate.h"		/* Datasets 				*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5Fprivate.h"         /* Files access                         */
#include "H5FDprivate.h"	/* File drivers				*/
#include "H5FDmpi.h"            /* MPI-based file drivers		*/
#include "H5Iprivate.h"		/* IDs			  		*/
#include "H5MMprivate.h"	/* Memory management			*/
#include "H5Pprivate.h"		/* Property lists			*/

#ifdef H5_HAVE_FPHDF5

#include "H5FPprivate.h"    /* Flexible PHDF5                               */

/*
 * The driver identification number, initialized at runtime if
 * H5_HAVE_FPHDF5 is defined. This allows applications to still have
 * the H5FD_FPHDF5 "constants" in their source code (it also makes this
 * file strictly ANSI compliant when H5_HAVE_FPHDF5 isn't defined)
 */
static hid_t H5FD_FPHDF5_g = 0;

/*
 * Private Prototypes
 */

/*
 * Callbacks
 */
static void    *H5FD_fphdf5_fapl_get(H5FD_t *_file);
static H5FD_t  *H5FD_fphdf5_open(const char *name, unsigned flags,
                                 hid_t fapl_id, haddr_t maxaddr);
static herr_t   H5FD_fphdf5_close(H5FD_t *_file);
static herr_t   H5FD_fphdf5_query(const H5FD_t *_f1, unsigned long *flags);
static haddr_t  H5FD_fphdf5_get_eoa(const H5FD_t *_file);
static herr_t   H5FD_fphdf5_set_eoa(H5FD_t *_file, haddr_t addr);
static haddr_t  H5FD_fphdf5_get_eof(const H5FD_t *_file);
static herr_t   H5FD_fphdf5_get_handle(H5FD_t *_file, hid_t fapl,
                                     void **file_handle);
static herr_t   H5FD_fphdf5_read(H5FD_t *_file, H5FD_mem_t mem_type, hid_t dxpl_id,
                                 haddr_t addr, size_t size, void *buf);
static herr_t   H5FD_fphdf5_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id,
                                  haddr_t addr, size_t size, const void *buf);
static herr_t   H5FD_fphdf5_flush(H5FD_t *_file, hid_t dxpl_id, unsigned closing);
static int      H5FD_fphdf5_mpi_rank(const H5FD_t *_file);
static int      H5FD_fphdf5_mpi_size(const H5FD_t *_file);
static MPI_Comm H5FD_fphdf5_barrier_communicator(const H5FD_t *_file);

/*
 * FPHDF5-specific file access properties
 */
typedef struct H5FD_fphdf5_fapl_t {
    MPI_Comm    comm;           /*communicator          */
    MPI_Comm    barrier_comm;   /*barrier communicator  */
    MPI_Info    info;           /*file information      */
    unsigned    sap_rank;       /*SAP's rank            */
    unsigned    capt_rank;      /*captain rank          */
} H5FD_fphdf5_fapl_t;

/*
 * The FPHDF5 file driver information
 */
const H5FD_class_mpi_t H5FD_fphdf5_g = {
    {   /* Start of superclass information */
    "fphdf5",                                   /*name                  */
    HADDR_MAX,                                  /*maxaddr               */
    H5F_CLOSE_SEMI,                             /*fc_degree             */
    NULL,                                       /*sb_size               */
    NULL,                                       /*sb_encode             */
    NULL,                                       /*sb_decode             */
    sizeof(H5FD_fphdf5_fapl_t),                 /*fapl_size             */
    H5FD_fphdf5_fapl_get,                       /*fapl_get              */
    NULL,                                       /*fapl_copy             */
    NULL,                                       /*fapl_free             */
    0,                                          /*dxpl_size             */
    NULL,                                       /*dxpl_copy             */
    NULL,                                       /*dxpl_free             */
    H5FD_fphdf5_open,                           /*open                  */
    H5FD_fphdf5_close,                          /*close                 */
    NULL,                                       /*cmp                   */
    H5FD_fphdf5_query,                          /*query                 */
    NULL,                                       /*alloc                 */
    NULL,                                       /*free                  */
    H5FD_fphdf5_get_eoa,                        /*get_eoa               */
    H5FD_fphdf5_set_eoa,                        /*set_eoa               */
    H5FD_fphdf5_get_eof,                        /*get_eof               */
    H5FD_fphdf5_get_handle,                     /*get_handle            */
    H5FD_fphdf5_read,                           /*read                  */
    H5FD_fphdf5_write,                          /*write                 */
    H5FD_fphdf5_flush,                          /*flush                 */
    NULL,                                       /*lock                  */
    NULL,                                       /*unlock                */
    H5FD_FLMAP_SINGLE                           /*fl_map                */
    },  /* End of superclass information */
    H5FD_fphdf5_mpi_rank,                       /*get_rank              */
    H5FD_fphdf5_mpi_size,                       /*get_size              */
    H5FD_fphdf5_barrier_communicator            /*get_comm              */
};


/*--------------------------------------------------------------------------
NAME
   H5FD_fphdf5_init_interface -- Initialize interface-specific information
USAGE
    herr_t H5FD_fphdf5_init_interface()
   
RETURNS
    Non-negative on success/Negative on failure
DESCRIPTION
    Initializes any interface-specific data or routines.  (Just calls
    H5FD_fphdf5_init currently).

--------------------------------------------------------------------------*/
static herr_t
H5FD_fphdf5_init_interface(void)
{
    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_fphdf5_init_interface)

    FUNC_LEAVE_NOAPI(H5FD_fphdf5_init())
} /* H5FD_fphdf5_init_interface() */


/*-------------------------------------------------------------------------
 * Function:	H5FD_fphdf5_init
 * Purpose:	Initialize this driver by registering the driver with the
 *		library.
 * Return:	Success:    The driver ID for the FPHDF5 driver.
 *		Failure:    Doesn't fail.
 * Programmer:	Bill Wendling
 *              30. January 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
hid_t
H5FD_fphdf5_init(void)
{
    hid_t   ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_init, FAIL)

    if (H5Iget_type(H5FD_FPHDF5_g) != H5I_VFL)
        H5FD_FPHDF5_g = H5FD_register((const H5FD_class_t *)&H5FD_fphdf5_g,sizeof(H5FD_class_mpi_t));

    /* Set return value */
    ret_value = H5FD_FPHDF5_g;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*---------------------------------------------------------------------------
 * Function:	H5FD_fphdf5_term
 *
 * Purpose:	Shut down the VFD
 *
 * Return:	<none>
 *
 * Programmer:  Quincey Koziol
 *              Friday, Jan 30, 2004
 *
 * Modification:
 *
 *---------------------------------------------------------------------------
 */
void
H5FD_fphdf5_term(void)
{
    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_fphdf5_term)

    /* Reset VFL ID */
    H5FD_FPHDF5_g=0;

    FUNC_LEAVE_NOAPI_VOID
} /* end H5FD_fphdf5_term() */


/*-------------------------------------------------------------------------
 * Function:	H5Pset_fapl_fphdf5
 * Purpose:	Store the user supplied MPIO communicator COMM and INFO
 *              in the file access property list FAPL_ID which can then
 *              be used to create and/or open the file. This function is
 *              available only in the parallel HDF5 library and is not
 *              collective.
 *
 *		COMM is the MPI communicator to be used for file open as
 *		defined in MPI_FILE_OPEN of MPI-2. This function does not
 *		make a duplicated communicator. Any modification to COMM
 *		after this function call returns may have an indeterminate
 *		effect on the access property list. Users should not
 *		modify the communicator while it is defined in a property
 *		list.
 *
 *		INFO is the MPI info object to be used for file open as
 *		defined in MPI_FILE_OPEN of MPI-2. This function does not
 *		make a duplicated info. Any modification to info after
 *		this function call returns may have an indeterminate effect
 *		on the access property list. Users should not modify the
 *		info while it is defined in a property list.
 * Return:	Success:    SUCCEED
 * 		Failure:    FAIL
 * Programmer:	Bill Wendling
 *		30. January 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_fapl_fphdf5(hid_t fapl_id, MPI_Comm comm, MPI_Comm barrier_comm,
                   MPI_Info info, unsigned sap_rank)
{
    H5FD_fphdf5_fapl_t  fa;
    H5P_genplist_t     *plist;
    int                 mrc, comm_size;
    herr_t              ret_value;
    
    FUNC_ENTER_API(H5Pset_fapl_fphdf5, FAIL)
    H5TRACE5("e","iMcMcMiIu",fapl_id,comm,barrier_comm,info,sap_rank);

    if (fapl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")

    /* Check arguments */
    if ((plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)) == NULL)
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list")

    if ((mrc = MPI_Comm_size(comm, &comm_size)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(FAIL, "MPI_Comm_size failed", mrc)

    /* Initialize driver specific properties */
    fa.comm = comm;
    fa.barrier_comm = barrier_comm;
    fa.info = info;
    fa.sap_rank = sap_rank;
    fa.capt_rank = (sap_rank + 1) % comm_size;

    ret_value = H5P_set_driver(plist, H5FD_FPHDF5, &fa);

done:
    FUNC_LEAVE_API(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5Pget_fapl_fphdf5
 * Purpose:     If the file access property list is set to the
 *              H5FD_FPHDF5 driver then this function returns the MPI
 *              communicator and information through the COMM and INFO
 *              pointers.
 * Return:      Success:    SUCCEED with the communicator and information
 *                          returned through the COMM and INFO arguments
 *                          if non-null. Neither piece of information is
 *                          copied and they are therefore valid only
 *                          until the file access property list is
 *                          modified or closed.
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              30. January 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
herr_t
H5Pget_fapl_fphdf5(hid_t fapl_id, MPI_Comm *comm, MPI_Comm *barrier_comm,
                   MPI_Info *info, unsigned *sap_rank, unsigned *capt_rank)
{
    H5FD_fphdf5_fapl_t *fa;
    H5P_genplist_t     *plist;
    herr_t              ret_value = SUCCEED;
    
    FUNC_ENTER_API(H5Pget_fapl_fphdf5, FAIL)
    H5TRACE6("e","i*Mc*Mc*Mi*Iu*Iu",fapl_id,comm,barrier_comm,info,sap_rank,
             capt_rank);

    if ((plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)) == NULL)
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list")

    if (H5P_get_driver(plist) != H5FD_FPHDF5)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "incorrect VFL driver")

    if ((fa = H5P_get_driver_info(plist)) == NULL)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "bad VFL driver info")

    if (comm)
        *comm = fa->comm;

    if (barrier_comm)
        *barrier_comm = fa->barrier_comm;

    if (info)
        *info = fa->info;

    if (sap_rank)
        *sap_rank = fa->sap_rank;

    if (capt_rank)
        *capt_rank = fa->capt_rank;

done:
    FUNC_LEAVE_API(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_file_id
 * Purpose:     Returns the file ID for the file.
 * Return:      Success:    File ID
 *              Failure:    Doesn't fail
 * Programmer:  Bill Wendling
 *              19. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
unsigned
H5FD_fphdf5_file_id(H5FD_t *_file)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t*)_file;
    unsigned        ret_value; 

    FUNC_ENTER_NOAPI(H5FD_fphdf5_file_id, 0)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = file->file_id;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_is_sap
 * Purpose:     Asks the question "Is this process the SAP?".
 * Return:      Success:    Non-zero if it is, 0 otherwise
 *              Failure:    Doesn't fails
 * Programmer:  Bill Wendling
 *              19. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
hbool_t
H5FD_fphdf5_is_sap(const H5FD_t *_file)
{
    const H5FD_fphdf5_t  *file = (const H5FD_fphdf5_t*)_file;
    hbool_t         ret_value = FALSE;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_is_sap, FALSE)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = ((unsigned)file->mpi_rank == H5FP_sap_rank);

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_is_captain
 * Purpose:     Asks the question "Is this process the captain?".
 * Return:      Success:    Non-zero if it is, 0 otherwise
 *              Failure:    Doesn't fails
 * Programmer:  Bill Wendling
 *              19. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
hbool_t
H5FD_fphdf5_is_captain(H5FD_t *_file)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t*)_file;
    hbool_t         ret_value = FALSE;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_is_captain, FALSE)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = ((unsigned)file->mpi_rank == H5FP_capt_rank);

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_is_fphdf5_driver
 * Purpose:     Asks the question "Is this an FPHDF5 driver?".
 * Return:      Success:    Non-zero if it is, 0 otherwise
 *              Failure:    Doesn't fails
 * Programmer:  Bill Wendling
 *              26. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
hbool_t
H5FD_is_fphdf5_driver(H5FD_t *_file)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t*)_file;
    hbool_t         ret_value = FALSE;

    FUNC_ENTER_NOAPI(H5FD_is_fphdf5_driver, FALSE)

    /* check args */
    assert(file);

    /* Set return value */
    ret_value = file->pub.driver_id == H5FD_FPHDF5;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5Pset_dxpl_fphdf5
 * Purpose:     Set the data transfer property list DXPL_ID to use
 *              transfer mode XFER_MODE. The property list can then be
 *              used to control the I/O transfer mode during data I/O
 *              operations. The valid transfer modes are:
 *
 *              H5FD_MPIO_INDEPENDENT:
 *                  Use independent I/O access (the default).
 *
 *              H5FD_MPIO_COLLECTIVE:
 *                  Use collective I/O access.
 * Return:      Success:    SUCCEED
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              10. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
herr_t
H5Pset_dxpl_fphdf5(hid_t dxpl_id, H5FD_mpio_xfer_t xfer_mode)
{
    H5P_genplist_t *plist;
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_API(H5Pset_dxpl_fphdf5, FAIL)
    H5TRACE2("e","iDt",dxpl_id,xfer_mode);
    
    if (dxpl_id == H5P_DEFAULT)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")

    /* Check arguments */
    if ((plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)) == NULL)
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    if (xfer_mode != H5FD_MPIO_INDEPENDENT && xfer_mode != H5FD_MPIO_COLLECTIVE)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "incorrect xfer_mode")

    /* Set the transfer mode */
    if (H5P_set(plist, H5D_XFER_IO_XFER_MODE_NAME, &xfer_mode) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")

    /* Initialize driver-specific properties */
    ret_value = H5P_set_driver(plist, H5FD_FPHDF5, NULL);

done:
    FUNC_LEAVE_API(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5Pget_dxpl_fphdf5
 * Purpose:     Queries the transfer mode current set in the data
 *              transfer property list DXPL_ID. This is not collective.
 * Return:      Success:    SUCCEED - with the transfer mode returned
 *                                    through the XFER_MODE argument if
 *                                    it is non-null.
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              10. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
herr_t
H5Pget_dxpl_fphdf5(hid_t dxpl_id, H5FD_mpio_xfer_t *xfer_mode)
{
    H5P_genplist_t *plist;
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_API(H5Pget_dxpl_fphdf5, FAIL)
    H5TRACE2("e","i*Dt",dxpl_id,xfer_mode);

    if ((plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)) == NULL)
        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")

    if (H5P_get_driver(plist) != H5FD_FPHDF5)
        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "incorrect VFL driver")

    /* Get the transfer mode */
    if (xfer_mode)
        if (H5P_get(plist, H5D_XFER_IO_XFER_MODE_NAME, xfer_mode) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to get value")

done:
    FUNC_LEAVE_API(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_fapl_get
 * Purpose:     Returns a file access property list which could be used
 *              to create another file the same as this one.
 * Return:      Success:    Ptr to new file access property list with all
 *                          fields copied from the file pointer.
 *              Failure:    NULL
 * Programmer:  Bill Wendling
 *              07. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static void *
H5FD_fphdf5_fapl_get(H5FD_t *_file)
{
    H5FD_fphdf5_t      *file = (H5FD_fphdf5_t*)_file;
    H5FD_fphdf5_fapl_t *fa = NULL;
    void               *ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_fapl_get, NULL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    if ((fa = H5MM_calloc(sizeof(H5FD_fphdf5_fapl_t))) == NULL)
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    /* These should both be copied. --rpm, 1999-08-13 */
    fa->comm = file->comm;
    fa->barrier_comm = file->barrier_comm;
    fa->info = file->info;

    /* Set return value */
    ret_value = fa;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_open
 * Purpose:     Opens a file with name NAME. The FLAGS are a bit field with
 *              purpose similar to the second argument of open(2) and
 *              which are defined in H5Fpublic.h. The file access
 *              property list FAPL_ID contains the properties driver
 *              properties and MAXADDR is the largest address which this
 *              file will be expected to access.  This is collective.
 * Return:      Success:    A new file pointer.
 *              Failure:    NULL
 * Programmer:  Bill Wendling
 *              05. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static H5FD_t *
H5FD_fphdf5_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
{
    H5FD_fphdf5_t              *file = NULL;
    MPI_File                    fh;
    int                         mpi_amode;
    int                         mpi_rank;
    int                         mpi_size;
    int                         mrc;
    MPI_Offset                  size;
    H5FD_fphdf5_fapl_t          _fa;
    const H5FD_fphdf5_fapl_t   *fa = NULL;
    H5P_genplist_t             *plist;
    unsigned long               feature_flags;
    hsize_t                     meta_block_size = 0;
    hsize_t                     sdata_block_size = 0;
    hsize_t                     threshold;
    hsize_t                     alignment;
    unsigned                    file_id;
    unsigned                    req_id = 0;
    H5FD_t                     *ret_value = NULL;

    /* Flag to indicate that the file was successfully opened */
    unsigned                    file_opened = FALSE;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_open, NULL)

    /* check args */
    assert(name);

    /* Obtain a pointer to fphdf5-specific file access properties */
    if ((plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)) == NULL)
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")

    if (fapl_id == H5P_FILE_ACCESS_DEFAULT || H5P_get_driver(plist) != H5FD_FPHDF5) {
        _fa.comm = MPI_COMM_SELF;           /*default*/
        _fa.barrier_comm = MPI_COMM_SELF;   /*default*/
        _fa.info = MPI_INFO_NULL;           /*default*/
        fa = &_fa;
    } else {
        fa = H5P_get_driver_info(plist);
        assert(fa);
    }

    /*
     * Convert HDF5 flags to MPI-IO flags. Some combinations are illegal;
     * let MPI-IO figure it out
     */
    mpi_amode = (flags & H5F_ACC_RDWR) ? MPI_MODE_RDWR : MPI_MODE_RDONLY;

    if (flags & H5F_ACC_CREAT)  mpi_amode |= MPI_MODE_CREATE;
    if (flags & H5F_ACC_EXCL)   mpi_amode |= MPI_MODE_EXCL;

    /* OKAY: CAST DISCARDS CONST */
    if ((mrc = MPI_File_open(H5FP_SAP_BARRIER_COMM, (char *)name, mpi_amode,
                             fa->info, &fh)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(NULL, "MPI_File_open failed", mrc)

    file_opened = TRUE;

    if (H5P_get(plist, H5F_ACS_META_BLOCK_SIZE_NAME, &meta_block_size) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get meta data block size")

    if (H5P_get(plist, H5F_ACS_SDATA_BLOCK_SIZE_NAME, &sdata_block_size) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get 'small data' block size")

    if (H5P_get(plist, H5F_ACS_ALIGN_THRHD_NAME, &threshold) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get alignment threshold")

    if (H5P_get(plist, H5F_ACS_ALIGN_NAME, &alignment) < 0)
        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get alignment")

    /* Retrieve the VFL driver feature flags */
    H5FD_fphdf5_query(NULL, &feature_flags);    /* doesn't fail */

    /* Inform the SAP that the file was opened */
    if (H5FP_request_open(H5FP_OBJ_FILE, maxaddr, feature_flags,
                          meta_block_size, sdata_block_size, threshold,
                          alignment, &file_id, &req_id) == FAIL)
        HGOTO_ERROR(H5E_FPHDF5, H5E_CANTOPENFILE, NULL, "can't inform SAP of file open")

    /* Broadcast the file ID */
    if ((mrc = MPI_Bcast(&file_id, 1, MPI_UNSIGNED,
                         (int)H5FP_capt_barrier_rank,
                         H5FP_SAP_BARRIER_COMM)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(NULL, "MPI_Bcast failed", mrc)

    /* Grab the rank of this process */
    if ((mrc = MPI_Comm_rank(H5FP_SAP_COMM, &mpi_rank)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(NULL, "MPI_Comm_rank failed", mrc)

    /* The captain rank will get the filesize and broadcast it. */
    if ((unsigned)mpi_rank == H5FP_capt_rank)
        /* Get current file size */
        if ((mrc = MPI_File_get_size(fh, &size)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(NULL, "MPI_File_get_size failed", mrc)

    /* Broadcast file size */
    if ((mrc = MPI_Bcast(&size, sizeof(MPI_Offset), MPI_BYTE,
                         (int)H5FP_capt_barrier_rank,
                         H5FP_SAP_BARRIER_COMM)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(NULL, "MPI_Bcast failed", mrc)

    /* Only if size > 0, truncate the file - if requested */
    if (size && (flags & H5F_ACC_TRUNC)) {
        if ((mrc = MPI_File_set_size(fh, (MPI_Offset)0)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(NULL, "MPI_File_set_size (file truncation) failed", mrc)

        /* Don't let any proc return until all have truncated the file. */
        if ((mrc = MPI_Barrier(H5FP_SAP_BARRIER_COMM)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(NULL, "MPI_Barrier failed", mrc)

        size = 0;
    }

    /* Grab the size of the communicator */
    if ((mrc = MPI_Comm_size(H5FP_SAP_COMM, &mpi_size)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(NULL, "MPI_Comm_size failed", mrc)

    /* Build the return value and initialize it */
    if ((file = H5MM_calloc(sizeof(H5FD_fphdf5_t))) == NULL)
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")

    file->file_id = file_id;
    file->f = fh;
    file->comm = fa->comm;
    file->info = fa->info;
    file->mpi_rank = mpi_rank;
    file->mpi_size = mpi_size;
    file->eof = H5FD_mpi_MPIOff_to_haddr(size);

    /* Set return value */
    ret_value = (H5FD_t *)file;

done:
    if (!ret_value && file_opened)
        MPI_File_close(&fh);

    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_close
 * Purpose:     Closes a file. This is collective.
 * Return:      Success:    SUCCEED
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              07. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD_fphdf5_close(H5FD_t *_file)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t *)_file;
    unsigned        req_id = 0;
    H5FP_status_t   status = H5FP_STATUS_OK;
    int             mrc;
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_close, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Tell the SAP that we're closing the file... */
    if (H5FP_request_close(_file, file->file_id, &req_id, &status) == FAIL)
        HGOTO_ERROR(H5E_IO, H5E_CANTCLOSEFILE, FAIL, "can't inform SAP of file close")

    /* MPI_File_close sets argument to MPI_FILE_NULL */
    if ((mrc = MPI_File_close(&file->f)) != MPI_SUCCESS)
        HMPI_GOTO_ERROR(FAIL, "MPI_File_close failed", mrc)

    /* Clean up other stuff */
    H5MM_xfree(file);

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_query
 * Purpose:     Set the flags that this VFL driver is capable of
 *              supporting. (listed in H5FDpublic.h)
 * Return:      Success:    SUCCEED
 *              Failure:    Doesn't fail.
 * Programmer:  Bill Wendling
 *              07. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD_fphdf5_query(const H5FD_t UNUSED *_file, unsigned long *flags /* out */)
{
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_query, FAIL)

    /* Set the VFL feature flags that this driver supports */
    if (flags) {
        *flags = 0;

        /* OK to aggregate metadata allocations */
        *flags |= H5FD_FEAT_AGGREGATE_METADATA;

        /*
         * Distinguish between updating the metadata accumulator on
         * writes and reads. This is particularly (perhaps only, even)
         * important for MPI-I/O where we guarantee that writes are
         * collective, but reads may not be. If we were to allow the
         * metadata accumulator to be written during a read operation,
         * the application would hang.
         */

#if 0
        /*
         * FIXME: For now, having metadata accumulate causes problems for
         * the SAP when it goes to allocate data (oddly enough, an
         * allocation can result in a call to H5FD_free...which can
         * result in a call to H5FD_write...which needs a data xfer
         * property list...but only when metadata accumulation is turned
         * on...go figure). Turn it off for now. -- BW 02/19/2003
         */

        /* OK to accumulate metadata for faster writes */
        *flags |= H5FD_FEAT_ACCUMULATE_METADATA_WRITE;
#endif  /* 0 */

        /* OK to aggregate "small" raw data allocations */
        *flags |= H5FD_FEAT_AGGREGATE_SMALLDATA;
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_get_eoa
 * Purpose:     Gets the end-of-address marker for the file. The EOA
 *              marker is the first address past the last byte allocated
 *              in the format address space.
 * Return:      Success:    The end-of-address marker.
 *              Failure:    HADDR_UNDEF
 * Programmer:  Bill Wendling
 *              07. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static haddr_t
H5FD_fphdf5_get_eoa(const H5FD_t *_file)
{
    const H5FD_fphdf5_t  *file = (const H5FD_fphdf5_t *)_file;
    unsigned        req_id = 0;
    H5FP_status_t   status = H5FP_STATUS_OK;
    haddr_t         ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_get_eoa, HADDR_UNDEF)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* The SAP's eoa field is correct */
    if (!H5FD_fphdf5_is_sap(_file))
        /* Retrieve the EOA information */
        if (H5FP_request_get_eoa(_file, &file->eoa, &req_id, &status))
            HGOTO_ERROR(H5E_FPHDF5, H5E_CANTRECV, HADDR_UNDEF, "can't retrieve eoa information")

    /* Set return value */
    ret_value = file->eoa;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_set_eoa
 * Purpose:     Set the end-of-address marker for the file. This function
 *              is called shortly after an existing HDF5 file is opened
 *              in order to tell the driver where the end of the HDF5
 *              data is located.
 * Return:      Success:    SUCCEED
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              06. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD_fphdf5_set_eoa(H5FD_t *_file, haddr_t addr)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t *)_file;
    unsigned        req_id = 0;
    H5FP_status_t   status = H5FP_STATUS_OK;
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_set_eoa, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* The SAP's eoa field is correct */
    if (!H5FD_fphdf5_is_sap(_file))
        /* Retrieve the EOA information */
        if (H5FP_request_set_eoa(_file, addr, &req_id, &status))
            HGOTO_ERROR(H5E_FPHDF5, H5E_CANTRECV, FAIL, "can't retrieve eoa information")

    file->eoa = addr;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_get_eof
 * Purpose:     Gets the end-of-file marker for the file. The EOF marker
 *              is the real size of the file.
 *
 *              The FPHDF5 driver doesn't bother keeping this field updated
 *              since that's a relatively expensive operation.
 *              Fortunately the library only needs the EOF just after the
 *              file is opened in order to determine whether the file is
 *              empty, truncated, or okay. Therefore, any MPIO I/O
 *              function will set its value to HADDR_UNDEF which is the
 *              error return value of this function.
 * Return:      Success:    The end-of-address marker
 *              Failure:    HADDR_UNDEF
 * Programmer:  Bill Wendling
 *              06. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static haddr_t
H5FD_fphdf5_get_eof(const H5FD_t *_file)
{
    const H5FD_fphdf5_t  *file = (const H5FD_fphdf5_t*)_file;
    haddr_t         ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_get_eof, HADDR_UNDEF)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = file->eof;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_get_handle
 * Purpose:     Returns the file handle of MPIO file driver.
 * Returns:     Success:    SUCCEED
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              06. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
*/
static herr_t  
H5FD_fphdf5_get_handle(H5FD_t *_file, hid_t UNUSED fapl, void** file_handle)
{   
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t *)_file;
    herr_t          ret_value = SUCCEED;
                            
    FUNC_ENTER_NOAPI(H5FD_fphdf5_get_handle, FAIL)

    /* check args */
    assert(file);
                                    
    if (!file_handle)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "file handle not valid")

    *file_handle = &file->f;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_read
 * Purpose:	Reads SIZE bytes of data from FILE beginning at address
 *              ADDR into buffer BUF according to data transfer
 *              properties in DXPL_ID using potentially complex file and
 *              buffer types to effect the transfer.
 *
 *              Reading past the end of the MPI file returns zeros
 *              instead of failing. MPI is able to coalesce requests
 *              from different processes (collective or independent).
 * Return:      Success:    SUCCEED - Result is stored in caller-supplied
 *                                    buffer BUF
 *              Failure:    FAIL - Contents of buffer BUF are undefined
 * Programmer:  Bill Wendling
 *              10. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD_fphdf5_read(H5FD_t *_file, H5FD_mem_t mem_type, hid_t dxpl_id,
                 haddr_t addr, size_t size, void *buf)
{
    H5FD_fphdf5_t      *file = (H5FD_fphdf5_t*)_file;
    MPI_Status          status;
    MPI_Offset          mpi_off;
    int                 size_i;             /* Integer copy of 'size' to read */
    int                 bytes_read;         /* Number of bytes read in */
    int                 mrc;                /* MPI return code */
    herr_t              ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_read, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);
    assert(buf);

    /* Make certain we have the correct type of property list */
    assert(H5I_get_type(dxpl_id) == H5I_GENPROP_LST);
    assert(H5P_isa_class(dxpl_id, H5P_DATASET_XFER) == TRUE);

    /* Portably initialize MPI status variable */
    HDmemset(&status, 0, sizeof(MPI_Status));

    /* Some numeric conversions */
    if (H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off) < 0)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from haddr_t to MPI offset")

    size_i = (int)size;
    if ((hsize_t)size_i != size)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from size_t to int")

    /* Only do real MPI stuff for raw data transfers */
    if(mem_type==H5FD_MEM_DRAW) {
        H5P_genplist_t     *plist;
        H5FD_mpio_xfer_t            xfer_mode;   /* I/O tranfer mode */
        MPI_Datatype buf_type;  /* MPI datatype for I/O operation */
        int n;
        int type_size;          /* MPI datatype used for I/O's size */
        int io_size;            /* Actual number of bytes requested */
        unsigned use_view_this_time = 0;        /* Flag to indicate we are using an MPI view */

        /* Obtain the data transfer properties */
        if ((plist = H5I_object(dxpl_id)) == NULL)
            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list")

        xfer_mode = H5P_peek_unsigned(plist, H5D_XFER_IO_XFER_MODE_NAME);

        /*
         * Set up for a fancy xfer using complex types, or single byte block.
         * We wouldn't need to rely on the use_view field if MPI semantics
         * allowed us to test that btype == ftype == MPI_BYTE (or even
         * MPI_TYPE_NULL, which could mean "use MPI_BYTE" by convention).
         */
        if (xfer_mode == H5FD_MPIO_COLLECTIVE) {
            MPI_Datatype    file_type;

            /* Remember that views are used */
            use_view_this_time = TRUE;

            /* Prepare for a full-blown xfer using btype, ftype, and disp */
            if (H5P_get(plist, H5FD_MPI_XFER_MEM_MPI_TYPE_NAME, &buf_type) < 0)
                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI-I/O type property")

            if (H5P_get(plist, H5FD_MPI_XFER_FILE_MPI_TYPE_NAME, &file_type) < 0)
                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI-I/O type property")

            /* Set the file view when we are using MPI derived types */
            if ((mrc = MPI_File_set_view(file->f, mpi_off, MPI_BYTE,
                                         file_type, H5FD_mpi_native_g,
                                         file->info)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mrc)

            /*
             * When using types, use the address as the displacement for
             * MPI_File_set_view and reset the address for the read to zero
             */
            mpi_off = 0;

            /* Read the data. */
            if ((mrc = MPI_File_read_at_all(file->f, mpi_off, buf, size_i,
                                            buf_type, &status)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at_all failed", mrc)

            /*
             * Reset the file view when we used MPI derived types
             */
            if ((mrc = MPI_File_set_view(file->f, (MPI_Offset)0, MPI_BYTE, MPI_BYTE,
                                         H5FD_mpi_native_g,  file->info)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mrc)
        } else {
            /*
             * Prepare for a simple xfer of a contiguous block of bytes. The
             * btype, ftype, and disp fields are not used.
             */
            buf_type = MPI_BYTE;

            /* Read the data. */
            if ((mrc = MPI_File_read_at(file->f, mpi_off, buf, size_i,
                                        buf_type, &status)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mrc)
        }

        /* How many bytes were actually read? */
        /* [This works because the "basic elements" we use for all our MPI derived
         *  types are MPI_BYTE.  We should be using the 'buf_type' for the MPI
         *  datatype in this call though... (We aren't because using it causes
         *  the LANL "qsc" machine to dump core - 12/19/03) - QAK]
         */
        if (MPI_SUCCESS != (mrc=MPI_Get_elements(&status, MPI_BYTE, &bytes_read)))
            HMPI_GOTO_ERROR(FAIL, "MPI_Get_elements failed", mrc)

        /* Get the type's size */
        if (MPI_SUCCESS != (mrc=MPI_Type_size(buf_type,&type_size)))
            HMPI_GOTO_ERROR(FAIL, "MPI_Type_size failed", mrc)

        /* Compute the actual number of bytes requested */
        io_size=type_size*size_i;

        /* Check for read failure */
        if (bytes_read<0 || bytes_read>io_size)
            HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file read failed")

        /*
         * This gives us zeroes beyond end of physical MPI file.
         */
        if ((n=(io_size-bytes_read)) > 0)
            HDmemset((char*)buf+bytes_read, 0, (size_t)n);
    } /* end if */
    else {
        /*
         * This is metadata - we want to try to read it from the SAP
         * first.
         */
        unsigned        req_id = 0;
        H5FP_status_t   sap_status = H5FP_STATUS_OK;

        if (H5FP_request_read_metadata(_file, file->file_id, dxpl_id, mem_type,
                                       addr, size, (uint8_t**)&buf,
                                       &req_id, &sap_status) != SUCCEED) {
            /* FIXME: The read failed, for some reason */
HDfprintf(stderr, "%s:%d: Metadata cache read failed!\n", FUNC, __LINE__);
        }

        if (sap_status == H5FP_STATUS_OK) {
            /* WAH-HOO! We've found it! We can leave now */
        } else if (sap_status == H5FP_STATUS_MDATA_NOT_CACHED) {
            /* Metadata isn't cached, so grab it from the file */
            if ((mrc = MPI_File_read_at(file->f, mpi_off, buf, size_i,
                                        MPI_BYTE, &status)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mrc)

            if ((mrc = MPI_Get_count(&status, MPI_BYTE, &bytes_read)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_Get_count failed", mrc)
        } else {
            /* FIXME: something bad happened */
HDfprintf(stderr, "%s:%d: Metadata cache read failed!\n", FUNC, __LINE__);
        }
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_write
 * Purpose:     Writes SIZE bytes of data to FILE beginning at address
 *              ADDR from buffer BUF according to data transfer
 *              properties in DXPL_ID using potentially complex file and
 *              buffer types to effect the transfer.
 *
 *              MPI is able to coalesce requests from different processes
 *              (collective and independent).
 * Return:      Success:    SUCCEED - USE_TYPES and OLD_USE_TYPES in the
 *                                    access params are altered.
 *              Failure:    FAIL - USE_TYPES and OLD_USE_TYPES in the
 *                                 access params may be altered.
 * Programmer:  Bill Wendling
 *              10. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD_fphdf5_write(H5FD_t *_file, H5FD_mem_t mem_type, hid_t dxpl_id,
                  haddr_t addr, size_t size, const void *buf)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t*)_file;
    int             size_i;
    unsigned        dumping = 0;
    H5P_genplist_t *plist;
    herr_t          ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_write, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);
    assert(buf);

    /* Make certain we have the correct type of property list */
    assert(H5I_get_type(dxpl_id) == H5I_GENPROP_LST);
    assert(H5P_isa_class(dxpl_id, H5P_DATASET_XFER) == TRUE);

    /* some numeric conversions */
    size_i = (int)size;
    if ((hsize_t)size_i != size)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from size to size_i")

    /* Obtain the data transfer properties */
    if ((plist = H5I_object(dxpl_id)) == NULL)
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list")

    if (H5P_exist_plist(plist, H5FD_FPHDF5_XFER_DUMPING_METADATA) > 0)
        if (H5P_get(plist, H5FD_FPHDF5_XFER_DUMPING_METADATA, &dumping) < 0)
            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI-I/O type property")

    /*
     * If metadata, write to the metadata cache but only if we're not
     * dumping the data from the SAP...
     */
    if (mem_type != H5FD_MEM_DRAW && !dumping) {
        unsigned        req_id = 0;
        H5FP_status_t   sap_status = H5FP_STATUS_OK;

        if (H5FP_request_write_metadata(_file, file->file_id, dxpl_id, mem_type,
                                        addr, size_i, buf, &req_id,
                                        &sap_status) != SUCCEED) {
            /* FIXME: Couldn't write metadata. This is bad... */
HDfprintf(stderr, "%s:%d: Couldn't write metadata to SAP (%d)\n",
          FUNC, __LINE__, sap_status);
        }

        switch (sap_status) {
        case H5FP_STATUS_OK:
            /* WAH-HOO! We've written it! We can leave now */
            /* Forget the EOF value (see H5FD_fphdf5_get_eof()) */
            file->eof = HADDR_UNDEF;
            HGOTO_DONE(SUCCEED)
        case H5FP_STATUS_FILE_CLOSING:
            HGOTO_DONE(SUCCEED)
        case H5FP_STATUS_DUMPING_FAILED:
        case H5FP_STATUS_OOM:
        case H5FP_STATUS_BAD_FILE_ID:
        default:
            /* FIXME: Something bad happened */
HDfprintf(stderr, "%s: Couldn't write metadata to SAP (%d)\n",
          FUNC, sap_status);
            break;
        }
    }

    /* FIXME: Should I check this return value or just pass it on out? */
    ret_value = H5FD_fphdf5_write_real(_file, mem_type, plist, addr, size_i, buf);

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_write_real
 * Purpose:     Do the actual writing to a file. Split apart from the
 *              H5FD_fphdf5_write call since I need to write things
 *              directly if the SAP is dumping data to me.
 * Return:      Success:    SUCCEED
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              12. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
herr_t
H5FD_fphdf5_write_real(H5FD_t *_file, H5FD_mem_t mem_type, H5P_genplist_t *plist,
                       haddr_t addr, int size, const void *buf)
{
    H5FD_fphdf5_t      *file = (H5FD_fphdf5_t*)_file;
    MPI_Status          status;
    MPI_Datatype        buf_type = MPI_BYTE;
    MPI_Offset          mpi_off;
    int                 mrc;
    int                 bytes_written;
    int                 type_size;      /* MPI datatype used for I/O's size */
    int                 io_size;        /* Actual number of bytes requested */
    unsigned            use_view_this_time = 0;
    herr_t              ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_write_real, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);
    assert(plist);
    assert(buf);

    /* Portably initialize MPI status variable */
    HDmemset(&status, 0, sizeof(MPI_Status));

    /* some numeric conversions */
    if (H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off) < 0)
        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from haddr to MPI off")

    /* Only check for fancy transfers with raw data I/O */
    if (mem_type == H5FD_MEM_DRAW) {
        H5FD_mpio_xfer_t    xfer_mode;   /* I/O tranfer mode */

        /* Obtain the data transfer properties */
        xfer_mode = (H5FD_mpio_xfer_t)H5P_peek_unsigned(plist, H5D_XFER_IO_XFER_MODE_NAME);

        /*
         * Set up for a fancy xfer using complex types, or single byte block.
         * We wouldn't need to rely on the use_view field if MPI semantics
         * allowed us to test that btype == ftype == MPI_BYTE (or even
         * MPI_TYPE_NULL, which could mean "use MPI_BYTE" by convention).
         */
        if (xfer_mode == H5FD_MPIO_COLLECTIVE) {
            MPI_Datatype    file_type;

            /* Remember that views are used */
            use_view_this_time = TRUE;

            /* Prepare for a full-blown xfer using btype, ftype, and disp */
            if (H5P_get(plist, H5FD_MPI_XFER_MEM_MPI_TYPE_NAME, &buf_type) < 0)
                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI-I/O type property")

            if (H5P_get(plist, H5FD_MPI_XFER_FILE_MPI_TYPE_NAME, &file_type) < 0)
                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get MPI-I/O type property")

            /* Set the file view when we are using MPI derived types */
            if ((mrc = MPI_File_set_view(file->f, mpi_off, MPI_BYTE,
                                         file_type, H5FD_mpi_native_g,
                                         file->info)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mrc)

            /*
             * When using types, use the address as the displacement for
             * MPI_File_set_view and reset the address for the read to zero
             */
            mpi_off = 0;
        }
    } /* end if */

    /* Write the data. */
    if (use_view_this_time) {
        /*OKAY: CAST DISCARDS CONST QUALIFIER*/
        if ((mrc = MPI_File_write_at_all(file->f, mpi_off, (void*)buf,
                                         size, buf_type, &status)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at_all failed", mrc)

        /* Reset the file view when we used MPI derived types */
        if ((mrc = MPI_File_set_view(file->f, (MPI_Offset)0, MPI_BYTE, MPI_BYTE,
                                     H5FD_mpi_native_g, file->info)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mrc)
    } /* end if */
    else {
        /*OKAY: CAST DISCARDS CONST QUALIFIER*/
        if ((mrc = MPI_File_write_at(file->f, mpi_off, (void*)buf,
                                     size, buf_type, &status)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at failed", mrc)
    }

    /* How many bytes were actually written? */
    /* [This works because the "basic elements" we use for all our MPI derived
     *  types are MPI_BYTE.  We should be using the 'buf_type' for the MPI
     *  datatype in this call though... (We aren't because using it causes
     *  the LANL "qsc" machine to dump core - 12/19/03) - QAK]
     */
    if (MPI_SUCCESS != (mrc=MPI_Get_elements(&status, MPI_BYTE, &bytes_written)))
        HMPI_GOTO_ERROR(FAIL, "MPI_Get_elements failed", mrc)

    /* Get the type's size */
    if (MPI_SUCCESS != (mrc=MPI_Type_size(buf_type,&type_size)))
        HMPI_GOTO_ERROR(FAIL, "MPI_Type_size failed", mrc)

    /* Compute the actual number of bytes requested */
    io_size=type_size*size;

    /* Check for write failure */
    if (bytes_written!=io_size)
        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "file write failed")

    /* Forget the EOF value (see H5FD_fphdf5_get_eof()) */
    file->eof = HADDR_UNDEF;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_flush
 * Purpose:     Makes sure that all data is on disk. This is collective.
 * Return:      Success:    SUCCEED
 *              Failure:    FAIL
 * Programmer:  Bill Wendling
 *              12. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static herr_t
H5FD_fphdf5_flush(H5FD_t *_file, hid_t dxpl_id, unsigned closing)
{
    H5FD_fphdf5_t  *file = (H5FD_fphdf5_t*)_file;
    MPI_Offset      mpi_off;
    int	            mrc;
    unsigned        req_id = 0;
    H5FP_status_t   status = H5FP_STATUS_OK;
    herr_t          ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_flush, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /*
     * Extend the file to make sure it's large enough, then sync.
     * Unfortunately, keeping track of EOF is an expensive operation, so
     * we can't just check whether EOF<EOA like with other drivers.
     * Therefore we'll just read the byte at EOA-1 and then write it
     * back.
     */
    if (file->eoa > file->last_eoa) {
        if (H5FD_mpi_haddr_to_MPIOff(file->eoa, &mpi_off) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "cannot convert from haddr_t to MPI_Offset")

        /* Extend the file's size */
        if ((mrc = MPI_File_set_size(file->f, mpi_off)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(FAIL, "MPI_File_set_size failed", mrc)

        /*
         * Don't let any proc return until all have extended the file.
         * (Prevents race condition where some processes go ahead and
         * write more data to the file before all the processes have
         * finished making it the shorter length, potentially truncating
         * the file and dropping the new data written)
         */
        if ((mrc = MPI_Barrier(H5FP_SAP_BARRIER_COMM)) != MPI_SUCCESS)
            HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mrc)

        /* Update the 'last' eoa value */
        file->last_eoa = file->eoa;
    }

    /* Only the captain process needs to flush the metadata. */
    if (H5FD_fphdf5_is_captain(_file)) {
        if (H5FP_request_flush_metadata(_file, file->file_id, dxpl_id,
                                        &req_id, &status) != SUCCEED)
            HGOTO_ERROR(H5E_FPHDF5, H5E_CANTFLUSH, FAIL, "can't flush metadata")

        /* Only sync the file if we are not going to immediately close it */
        if (!closing)
            if ((mrc = MPI_File_sync(file->f)) != MPI_SUCCESS)
                HMPI_GOTO_ERROR(FAIL, "MPI_File_sync failed", mrc)
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_mpi_rank
 * Purpose:     Returns the MPI rank for a process
 * Return:      Success:    MPI rank
 *              Failure:    Doesn't fail
 * Programmer:  Bill Wendling
 *              30. January 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static int
H5FD_fphdf5_mpi_rank(const H5FD_t *_file)
{
    const H5FD_fphdf5_t  *file = (const H5FD_fphdf5_t*)_file;
    int             ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_mpi_rank, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = file->mpi_rank;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}


/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_mpi_size
 * Purpose:     Returns the number of MPI processes
 * Return:      Success:    Number of MPI processes
 *              Failure:    Doesn't fail
 * Programmer:  Bill Wendling
 *              30. January 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static int
H5FD_fphdf5_mpi_size(const H5FD_t *_file)
{
    const H5FD_fphdf5_t  *file = (const H5FD_fphdf5_t*)_file;
    int             ret_value; 

    FUNC_ENTER_NOAPI(H5FD_fphdf5_mpi_size, FAIL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = file->mpi_size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}

/*-------------------------------------------------------------------------
 * Function:    H5FD_fphdf5_barrier_communicator
 * Purpose:     Returns the MPI communicator for the file that can be
 *              used in an MPI_Barrier() statement for the client
 *              processes.
 * Return:      Success:    The barrier communicator
 *              Failure:    NULL
 * Programmer:  Bill Wendling
 *              10. February 2003
 * Modifications:
 *-------------------------------------------------------------------------
 */
static MPI_Comm
H5FD_fphdf5_barrier_communicator(const H5FD_t *_file)
{
    const H5FD_fphdf5_t  *file = (const H5FD_fphdf5_t*)_file;
    MPI_Comm        ret_value;

    FUNC_ENTER_NOAPI(H5FD_fphdf5_barrier_communicator, MPI_COMM_NULL)

    /* check args */
    assert(file);
    assert(file->pub.driver_id == H5FD_FPHDF5);

    /* Set return value */
    ret_value = file->barrier_comm;

done:
    FUNC_LEAVE_NOAPI(ret_value)
}

#endif  /* H5_HAVE_FPHDF5 */