path: root/src/H5Dcontig.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * 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 COPYING file, which can be found at the root of the source code       *
 * distribution tree, or in https://www.hdfgroup.org/licenses.               *
 * If you do not have access to either file, you may request a copy from     *
 * help@hdfgroup.org.                                                        *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
 * Purpose:
 *      Contiguous dataset I/O functions. These routines are similar to
 *      the H5D_chunk_* routines and really only an abstract way of dealing
 *      with the data sieve buffer from H5F_seq_read/write.
 */

/****************/
/* Module Setup */
/****************/

#include "H5Dmodule.h" /* This source code file is part of the H5D module */

/***********/
/* Headers */
/***********/
#include "H5private.h"   /* Generic Functions            */
#include "H5CXprivate.h" /* API Contexts                 */
#include "H5Dpkg.h"      /* Dataset functions            */
#include "H5Eprivate.h"  /* Error handling               */
#include "H5Fprivate.h"  /* Files                        */
#include "H5FDprivate.h" /* File drivers                 */
#include "H5FLprivate.h" /* Free Lists                   */
#include "H5Iprivate.h"  /* IDs                          */
#include "H5MFprivate.h" /* File memory management       */
#include "H5MMprivate.h" /* Memory management			*/
#include "H5FOprivate.h" /* File objects                 */
#include "H5Oprivate.h"  /* Object headers               */
#include "H5Pprivate.h"  /* Property lists               */
#include "H5PBprivate.h" /* Page Buffer	                 */
#include "H5VMprivate.h" /* Vector and array functions   */

/****************/
/* Local Macros */
/****************/

/******************/
/* Local Typedefs */
/******************/

/* Callback info for sieve buffer readvv operation */
typedef struct H5D_contig_readvv_sieve_ud_t {
    H5F_shared_t               *f_sh;         /* Shared file for dataset */
    H5D_rdcdc_t                *dset_contig;  /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig; /* Contiguous storage info for this I/O operation */
    unsigned char              *rbuf;         /* Pointer to buffer to fill */
} H5D_contig_readvv_sieve_ud_t;

/* Callback info for [plain] readvv operation */
typedef struct H5D_contig_readvv_ud_t {
    H5F_shared_t  *f_sh;      /* Shared file for dataset */
    haddr_t        dset_addr; /* Address of dataset */
    unsigned char *rbuf;      /* Pointer to buffer to fill */
} H5D_contig_readvv_ud_t;

/* Callback info for sieve buffer writevv operation */
typedef struct H5D_contig_writevv_sieve_ud_t {
    H5F_shared_t               *f_sh;         /* Shared file for dataset */
    H5D_rdcdc_t                *dset_contig;  /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig; /* Contiguous storage info for this I/O operation */
    const unsigned char        *wbuf;         /* Pointer to buffer to write */
} H5D_contig_writevv_sieve_ud_t;

/* Callback info for [plain] writevv operation */
typedef struct H5D_contig_writevv_ud_t {
    H5F_shared_t        *f_sh;      /* Shared file for dataset */
    haddr_t              dset_addr; /* Address of dataset */
    const unsigned char *wbuf;      /* Pointer to buffer to write */
} H5D_contig_writevv_ud_t;

/********************/
/* Local Prototypes */
/********************/

/* Layout operation callbacks */
static herr_t  H5D__contig_construct(H5F_t *f, H5D_t *dset);
static herr_t  H5D__contig_init(H5F_t *f, const H5D_t *dset, hid_t dapl_id);
static herr_t  H5D__contig_io_init(H5D_io_info_t *io_info, H5D_dset_io_info_t *dinfo);
static herr_t  H5D__contig_mdio_init(H5D_io_info_t *io_info, H5D_dset_io_info_t *dinfo);
static ssize_t H5D__contig_readvv(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dinfo,
                                  size_t dset_max_nseq, size_t *dset_curr_seq, size_t dset_len_arr[],
                                  hsize_t dset_offset_arr[], size_t mem_max_nseq, size_t *mem_curr_seq,
                                  size_t mem_len_arr[], hsize_t mem_offset_arr[]);
static ssize_t H5D__contig_writevv(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dinfo,
                                   size_t dset_max_nseq, size_t *dset_curr_seq, size_t dset_len_arr[],
                                   hsize_t dset_offset_arr[], size_t mem_max_nseq, size_t *mem_curr_seq,
                                   size_t mem_len_arr[], hsize_t mem_offset_arr[]);
static herr_t  H5D__contig_flush(H5D_t *dset);
static herr_t  H5D__contig_io_term(H5D_io_info_t *io_info, H5D_dset_io_info_t *di);

/* Helper routines */
static herr_t H5D__contig_write_one(H5D_io_info_t *io_info, H5D_dset_io_info_t *dset_info, hsize_t offset,
                                    size_t size);
static herr_t H5D__contig_may_use_select_io(H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info,
                                            H5D_io_op_type_t op_type);

/*********************/
/* Package Variables */
/*********************/

/* Contiguous storage layout I/O ops */
const H5D_layout_ops_t H5D_LOPS_CONTIG[1] = {{
    H5D__contig_construct,      /* construct */
    H5D__contig_init,           /* init */
    H5D__contig_is_space_alloc, /* is_space_alloc */
    H5D__contig_is_data_cached, /* is_data_cached */
    H5D__contig_io_init,        /* io_init */
    H5D__contig_mdio_init,      /* mdio_init */
    H5D__contig_read,           /* ser_read */
    H5D__contig_write,          /* ser_write */
    H5D__contig_readvv,         /* readvv */
    H5D__contig_writevv,        /* writevv */
    H5D__contig_flush,          /* flush */
    H5D__contig_io_term,        /* io_term */
    NULL                        /* dest */
}};

/*******************/
/* Local Variables */
/*******************/

/* Declare a PQ free list to manage the sieve buffer information */
H5FL_BLK_DEFINE(sieve_buf);

/* Declare extern the free list to manage blocks of type conversion data */
H5FL_BLK_EXTERN(type_conv);

/* Declare extern the free list to manage the H5D_piece_info_t struct */
H5FL_EXTERN(H5D_piece_info_t);

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_alloc
 *
 * Purpose:	Allocate file space for a contiguously stored dataset
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_alloc(H5F_t *f, H5O_storage_contig_t *storage /*out */)
{
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* check args */
    assert(f);
    assert(storage);

    /* Allocate space for the contiguous data */
    if (HADDR_UNDEF == (storage->addr = H5MF_alloc(f, H5FD_MEM_DRAW, storage->size)))
        HGOTO_ERROR(H5E_IO, H5E_NOSPACE, FAIL, "unable to reserve file space");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_alloc */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_fill
 *
 * Purpose:	Write fill values to a contiguously stored dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_fill(H5D_t *dset)
{
    H5D_io_info_t      ioinfo;       /* Dataset I/O info */
    H5D_dset_io_info_t dset_info;    /* Dset info */
    H5D_storage_t      store;        /* Union of storage info for dataset */
    hssize_t           snpoints;     /* Number of points in space (for error checking) */
    size_t             npoints;      /* Number of points in space */
    hsize_t            offset;       /* Offset of dataset */
    size_t             max_temp_buf; /* Maximum size of temporary buffer */
#ifdef H5_HAVE_PARALLEL
    MPI_Comm mpi_comm = MPI_COMM_NULL; /* MPI communicator for file */
    int      mpi_rank = (-1);          /* This process's rank  */
    int      mpi_code;                 /* MPI return code */
    bool     blocks_written = false;   /* Flag to indicate that chunk was actually written */
    bool     using_mpi =
        false; /* Flag to indicate that the file is being accessed with an MPI-capable file driver */
#endif         /* H5_HAVE_PARALLEL */
    H5D_fill_buf_info_t fb_info;                /* Dataset's fill buffer info */
    bool                fb_info_init = false;   /* Whether the fill value buffer has been initialized */
    herr_t              ret_value    = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    assert(dset && H5D_CONTIGUOUS == dset->shared->layout.type);
    assert(H5_addr_defined(dset->shared->layout.storage.u.contig.addr));
    assert(dset->shared->layout.storage.u.contig.size > 0);
    assert(dset->shared->space);
    assert(dset->shared->type);

#ifdef H5_HAVE_PARALLEL
    /* Retrieve MPI parameters */
    if (H5F_HAS_FEATURE(dset->oloc.file, H5FD_FEAT_HAS_MPI)) {
        /* Get the MPI communicator */
        if (MPI_COMM_NULL == (mpi_comm = H5F_mpi_get_comm(dset->oloc.file)))
            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI communicator");

        /* Get the MPI rank */
        if ((mpi_rank = H5F_mpi_get_rank(dset->oloc.file)) < 0)
            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");

        /* Set the MPI-capable file driver flag */
        using_mpi = true;
    }  /* end if */
#endif /* H5_HAVE_PARALLEL */

    /* Initialize storage info for this dataset */
    store.contig.dset_addr = dset->shared->layout.storage.u.contig.addr;
    store.contig.dset_size = dset->shared->layout.storage.u.contig.size;

    /* Get the number of elements in the dataset's dataspace */
    if ((snpoints = H5S_GET_EXTENT_NPOINTS(dset->shared->space)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "dataset has negative number of elements");
    H5_CHECKED_ASSIGN(npoints, size_t, snpoints, hssize_t);

    /* Get the maximum size of temporary buffers */
    if (H5CX_get_max_temp_buf(&max_temp_buf) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve max. temp. buf size");

    /* Initialize the fill value buffer */
    if (H5D__fill_init(&fb_info, NULL, NULL, NULL, NULL, NULL, &dset->shared->dcpl_cache.fill,
                       dset->shared->type, npoints, max_temp_buf) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "can't initialize fill buffer info");
    fb_info_init = true;

    /* Start at the beginning of the dataset */
    offset = 0;

    /* Simple setup for dataset I/O info struct */
    ioinfo.op_type = H5D_IO_OP_WRITE;

    dset_info.dset      = (H5D_t *)dset;
    dset_info.store     = &store;
    dset_info.buf.cvp   = fb_info.fill_buf;
    dset_info.mem_space = NULL;
    ioinfo.dsets_info   = &dset_info;
    ioinfo.f_sh         = H5F_SHARED(dset->oloc.file);

    /*
     * Fill the entire current extent with the fill value.  We can do
     * this quite efficiently by making sure we copy the fill value
     * in relatively large pieces.
     */

    /* Loop through writing the fill value to the dataset */
    while (npoints > 0) {
        size_t curr_points; /* Number of elements to write on this iteration of the loop */
        size_t size;        /* Size of buffer to write */

        /* Compute # of elements and buffer size to write for this iteration */
        curr_points = MIN(fb_info.elmts_per_buf, npoints);
        size        = curr_points * fb_info.file_elmt_size;

        /* Check for VL datatype & non-default fill value */
        if (fb_info.has_vlen_fill_type)
            /* Re-fill the buffer to use for this I/O operation */
            if (H5D__fill_refill_vl(&fb_info, curr_points) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTCONVERT, FAIL, "can't refill fill value buffer");

#ifdef H5_HAVE_PARALLEL
        /* Check if this file is accessed with an MPI-capable file driver */
        if (using_mpi) {
            /* Write the chunks out from only one process */
            /* !! Use the internal "independent" DXPL!! -QAK */
            if (H5_PAR_META_WRITE == mpi_rank) {
                if (H5D__contig_write_one(&ioinfo, &dset_info, offset, size) < 0) {
                    /* If writing fails, push an error and stop writing, but
                     * still participate in following MPI_Barrier.
                     */
                    blocks_written = true;
                    HDONE_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset");
                    break;
                }
            }

            /* Indicate that blocks are being written */
            blocks_written = true;
        } /* end if */
        else {
#endif /* H5_HAVE_PARALLEL */
            H5_CHECK_OVERFLOW(size, size_t, hsize_t);
            if (H5D__contig_write_one(&ioinfo, &dset_info, offset, size) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset");
#ifdef H5_HAVE_PARALLEL
        } /* end else */
#endif    /* H5_HAVE_PARALLEL */

        npoints -= curr_points;
        offset += size;
    } /* end while */

#ifdef H5_HAVE_PARALLEL
    /* Only need to block at the barrier if we actually wrote fill values */
    /* And if we are using an MPI-capable file driver */
    if (using_mpi && blocks_written) {
        /* Wait at barrier to avoid race conditions where some processes are
         * still writing out fill values and other processes race ahead to data
         * in, getting bogus data.
         */
        if (MPI_SUCCESS != (mpi_code = MPI_Barrier(mpi_comm)))
            HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code)
    }  /* end if */
#endif /* H5_HAVE_PARALLEL */

done:
    /* Release the fill buffer info, if it's been initialized */
    if (fb_info_init && H5D__fill_term(&fb_info) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "Can't release fill buffer info");

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_fill() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_delete
 *
 * Purpose:	Delete the file space for a contiguously stored dataset
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_delete(H5F_t *f, const H5O_storage_t *storage)
{
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* check args */
    assert(f);
    assert(storage);

    /* Free the file space for the chunk */
    if (H5MF_xfree(f, H5FD_MEM_DRAW, storage->u.contig.addr, storage->u.contig.size) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "unable to free contiguous storage space");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_delete */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_construct
 *
 * Purpose:	Constructs new contiguous layout information for dataset
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_construct(H5F_t *f, H5D_t *dset)
{
    hssize_t snelmts;             /* Temporary holder for number of elements in dataspace */
    hsize_t  nelmts;              /* Number of elements in dataspace */
    size_t   dt_size;             /* Size of datatype */
    hsize_t  tmp_size;            /* Temporary holder for raw data size */
    size_t   tmp_sieve_buf_size;  /* Temporary holder for sieve buffer size */
    unsigned u;                   /* Local index variable */
    herr_t   ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity checks */
    assert(f);
    assert(dset);

    /*
     * The maximum size of the dataset cannot exceed the storage size.
     * Also, only the slowest varying dimension of a simple dataspace
     * can be extendible (currently only for external data storage).
     */

    /* Check for invalid dataset dimensions */
    for (u = 0; u < dset->shared->ndims; u++)
        if (dset->shared->max_dims[u] > dset->shared->curr_dims[u])
            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL,
                        "extendible contiguous non-external dataset not allowed");

    /* Retrieve the number of elements in the dataspace */
    if ((snelmts = H5S_GET_EXTENT_NPOINTS(dset->shared->space)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve number of elements in dataspace");
    nelmts = (hsize_t)snelmts;

    /* Get the datatype's size */
    if (0 == (dt_size = H5T_GET_SIZE(dset->shared->type)))
        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve size of datatype");

    /* Compute the size of the dataset's contiguous storage */
    tmp_size = nelmts * dt_size;

    /* Check for overflow during multiplication */
    if (nelmts != (tmp_size / dt_size))
        HGOTO_ERROR(H5E_DATASET, H5E_OVERFLOW, FAIL, "size of dataset's storage overflowed");

    /* Assign the dataset's contiguous storage size */
    dset->shared->layout.storage.u.contig.size = tmp_size;

    /* Get the sieve buffer size for the file */
    tmp_sieve_buf_size = H5F_SIEVE_BUF_SIZE(f);

    /* Adjust the sieve buffer size to the smaller one between the dataset size and the buffer size
     * from the file access property. (SLU - 2012/3/30) */
    if (tmp_size < tmp_sieve_buf_size)
        dset->shared->cache.contig.sieve_buf_size = tmp_size;
    else
        dset->shared->cache.contig.sieve_buf_size = tmp_sieve_buf_size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_construct() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_init
 *
 * Purpose:	Initialize the contiguous info for a dataset.  This is
 *		called when the dataset is initialized.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_init(H5F_t H5_ATTR_UNUSED *f, const H5D_t *dset, hid_t H5_ATTR_UNUSED dapl_id)
{
    hsize_t tmp_size;            /* Temporary holder for raw data size */
    size_t  tmp_sieve_buf_size;  /* Temporary holder for sieve buffer size */
    herr_t  ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(f);
    assert(dset);

    /* Compute the size of the contiguous storage for versions of the
     * layout message less than version 3 because versions 1 & 2 would
     * truncate the dimension sizes to 32-bits of information. - QAK 5/26/04
     */
    if (dset->shared->layout.version < 3) {
        hssize_t snelmts; /* Temporary holder for number of elements in dataspace */
        hsize_t  nelmts;  /* Number of elements in dataspace */
        size_t   dt_size; /* Size of datatype */

        /* Retrieve the number of elements in the dataspace */
        if ((snelmts = H5S_GET_EXTENT_NPOINTS(dset->shared->space)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve number of elements in dataspace");
        nelmts = (hsize_t)snelmts;

        /* Get the datatype's size */
        if (0 == (dt_size = H5T_GET_SIZE(dset->shared->type)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to retrieve size of datatype");

        /* Compute the size of the dataset's contiguous storage */
        tmp_size = nelmts * dt_size;

        /* Check for overflow during multiplication */
        if (nelmts != (tmp_size / dt_size))
            HGOTO_ERROR(H5E_DATASET, H5E_OVERFLOW, FAIL, "size of dataset's storage overflowed");

        /* Assign the dataset's contiguous storage size */
        dset->shared->layout.storage.u.contig.size = tmp_size;
    } /* end if */
    else
        tmp_size = dset->shared->layout.storage.u.contig.size;

    /* Get the sieve buffer size for the file */
    tmp_sieve_buf_size = H5F_SIEVE_BUF_SIZE(dset->oloc.file);

    /* Adjust the sieve buffer size to the smaller one between the dataset size and the buffer size
     * from the file access property.  (SLU - 2012/3/30) */
    if (tmp_size < tmp_sieve_buf_size)
        dset->shared->cache.contig.sieve_buf_size = tmp_size;
    else
        dset->shared->cache.contig.sieve_buf_size = tmp_sieve_buf_size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_init() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_is_space_alloc
 *
 * Purpose:	Query if space is allocated for layout
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
bool
H5D__contig_is_space_alloc(const H5O_storage_t *storage)
{
    bool ret_value = false; /* Return value */

    FUNC_ENTER_PACKAGE_NOERR

    /* Sanity checks */
    assert(storage);

    /* Set return value */
    ret_value = (bool)H5_addr_defined(storage->u.contig.addr);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_is_space_alloc() */

/*-------------------------------------------------------------------------
 * Function:    H5D__contig_is_data_cached
 *
 * Purpose:     Query if raw data is cached for dataset
 *
 * Return:      Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
bool
H5D__contig_is_data_cached(const H5D_shared_t *shared_dset)
{
    FUNC_ENTER_PACKAGE_NOERR

    /* Sanity checks */
    assert(shared_dset);

    FUNC_LEAVE_NOAPI(shared_dset->cache.contig.sieve_size > 0)
} /* end H5D__contig_is_data_cached() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_io_init
 *
 * Purpose:	Performs initialization before any sort of I/O on the raw data
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_io_init(H5D_io_info_t *io_info, H5D_dset_io_info_t *dinfo)
{
    H5D_t *dataset = dinfo->dset; /* Local pointer to dataset info */

    hssize_t old_offset[H5O_LAYOUT_NDIMS];  /* Old selection offset */
    htri_t   file_space_normalized = false; /* File dataspace was normalized */

    int sf_ndims; /* The number of dimensions of the file dataspace (signed) */

    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    dinfo->store->contig.dset_addr = dataset->shared->layout.storage.u.contig.addr;
    dinfo->store->contig.dset_size = dataset->shared->layout.storage.u.contig.size;

    /* Initialize piece info */
    dinfo->layout_io_info.contig_piece_info = NULL;

    /* Get layout for dataset */
    dinfo->layout = &(dataset->shared->layout);

    /* Get dim number and dimensionality for each dataspace */
    if ((sf_ndims = H5S_GET_EXTENT_NDIMS(dinfo->file_space)) < 0)
        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "unable to get dimension number");

    /* Normalize hyperslab selections by adjusting them by the offset */
    /* (It might be worthwhile to normalize both the file and memory dataspaces
     * before any (contiguous, chunked, etc) file I/O operation, in order to
     * speed up hyperslab calculations by removing the extra checks and/or
     * additions involving the offset and the hyperslab selection -QAK)
     */
    if ((file_space_normalized = H5S_hyper_normalize_offset(dinfo->file_space, old_offset)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_BADSELECT, FAIL, "unable to normalize dataspace by offset");

    /* if selected elements exist */
    if (dinfo->nelmts) {
        int               u;
        H5D_piece_info_t *new_piece_info; /* piece information to insert into skip list */

        /* Get copy of dset file_space, so it can be changed temporarily
         * purpose
         * This tmp_fspace allows multiple write before close dset */
        H5S_t *tmp_fspace; /* Temporary file dataspace */

        /* Create "temporary" chunk for selection operations (copy file space) */
        if (NULL == (tmp_fspace = H5S_copy(dinfo->file_space, true, false)))
            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy memory space");

        /* Add temporary chunk to the list of pieces */
        /* collect piece_info into Skip List */
        /* Allocate the file & memory chunk information */
        if (NULL == (new_piece_info = H5FL_MALLOC(H5D_piece_info_t))) {
            (void)H5S_close(tmp_fspace);
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate chunk info");
        } /* end if */

        /* Set the piece index */
        new_piece_info->index = 0;

        /* Set the file chunk dataspace */
        new_piece_info->fspace        = tmp_fspace;
        new_piece_info->fspace_shared = false;

        /* Set the memory chunk dataspace */
        /* same as one chunk, just use dset mem space */
        new_piece_info->mspace = dinfo->mem_space;

        /* set true for sharing mem space with dset, which means
         * fspace gets free by application H5Sclose(), and
         * doesn't require providing layout_ops.io_term() for H5D_LOPS_CONTIG.
         */
        new_piece_info->mspace_shared = true;

        /* Set the number of points */
        new_piece_info->piece_points = dinfo->nelmts;

        /* Copy the piece's coordinates */
        for (u = 0; u < sf_ndims; u++)
            new_piece_info->scaled[u] = 0;
        new_piece_info->scaled[sf_ndims] = 0;

        /* make connection to related dset info from this piece_info */
        new_piece_info->dset_info = dinfo;

        /* get dset file address for piece */
        new_piece_info->faddr = dinfo->dset->shared->layout.storage.u.contig.addr;

        /* Initialize in-place type conversion info. Start with it disabled. */
        new_piece_info->in_place_tconv = false;
        new_piece_info->buf_off        = 0;

        new_piece_info->filtered_dset = dinfo->dset->shared->dcpl_cache.pline.nused > 0;

        /* Calculate type conversion buffer size and check for in-place conversion if necessary.  Currently
         * only implemented for selection I/O. */
        if (io_info->use_select_io != H5D_SELECTION_IO_MODE_OFF &&
            !(dinfo->type_info.is_xform_noop && dinfo->type_info.is_conv_noop))
            H5D_INIT_PIECE_TCONV(io_info, dinfo, new_piece_info)

        /* Save piece to dataset info struct so it is freed at the end of the
         * operation */
        dinfo->layout_io_info.contig_piece_info = new_piece_info;

        /* Add piece to piece_count */
        io_info->piece_count++;
    } /* end if */

    /* Check if we're performing selection I/O if it hasn't been disabled
     * already */
    if (io_info->use_select_io != H5D_SELECTION_IO_MODE_OFF)
        if (H5D__contig_may_use_select_io(io_info, dinfo, io_info->op_type) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't check if selection I/O is possible");

done:
    if (ret_value < 0) {
        if (H5D__contig_io_term(io_info, dinfo) < 0)
            HDONE_ERROR(H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release dataset I/O info");
    } /* end if */

    if (file_space_normalized) {
        /* (Casting away const OK -QAK) */
        if (H5S_hyper_denormalize_offset(dinfo->file_space, old_offset) < 0)
            HDONE_ERROR(H5E_DATASET, H5E_BADSELECT, FAIL, "unable to normalize dataspace by offset");
    } /* end if */

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_io_init() */

/*-------------------------------------------------------------------------
 * Function:   H5D__contig_mdio_init
 *
 * Purpose:    Performs second phase of initialization for multi-dataset
 *             I/O.  Currently just adds data block to sel_pieces.
 *
 * Return:     Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_mdio_init(H5D_io_info_t *io_info, H5D_dset_io_info_t *dinfo)
{
    FUNC_ENTER_PACKAGE_NOERR

    /* Add piece if it exists */
    if (dinfo->layout_io_info.contig_piece_info) {
        assert(io_info->sel_pieces);
        assert(io_info->pieces_added < io_info->piece_count);

        /* Add contiguous data block to sel_pieces */
        io_info->sel_pieces[io_info->pieces_added] = dinfo->layout_io_info.contig_piece_info;

        /* Update pieces_added */
        io_info->pieces_added++;
    }

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5D__contig_mdio_init() */

/*-------------------------------------------------------------------------
 * Function:    H5D__contig_may_use_select_io
 *
 * Purpose:    A small internal function to if it may be possible to use
 *             selection I/O.
 *
 * Return:    true/false/FAIL
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_may_use_select_io(H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info,
                              H5D_io_op_type_t op_type)
{
    const H5D_t *dataset   = NULL;    /* Local pointer to dataset info */
    herr_t       ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(io_info);
    assert(dset_info);
    assert(dset_info->dset);
    assert(op_type == H5D_IO_OP_READ || op_type == H5D_IO_OP_WRITE);

    dataset = dset_info->dset;

    /* None of the reasons this function might disable selection I/O are relevant to parallel, so no need to
     * update no_selection_io_cause since we're only keeping track of the reason for no selection I/O in
     * parallel (for now) */

    /* Don't use selection I/O if it's globally disabled, if it's not a contiguous dataset, or if the sieve
     * buffer exists (write) or is dirty (read) */
    if (dset_info->layout_ops.readvv != H5D__contig_readvv) {
        io_info->use_select_io = H5D_SELECTION_IO_MODE_OFF;
        io_info->no_selection_io_cause |= H5D_SEL_IO_NOT_CONTIGUOUS_OR_CHUNKED_DATASET;
    }
    else if ((op_type == H5D_IO_OP_READ && dataset->shared->cache.contig.sieve_dirty) ||
             (op_type == H5D_IO_OP_WRITE && dataset->shared->cache.contig.sieve_buf)) {
        io_info->use_select_io = H5D_SELECTION_IO_MODE_OFF;
        io_info->no_selection_io_cause |= H5D_SEL_IO_CONTIGUOUS_SIEVE_BUFFER;
    }
    else {
        bool page_buf_enabled;

        assert(dset_info->layout_ops.writevv == H5D__contig_writevv);

        /* Check if the page buffer is enabled */
        if (H5PB_enabled(io_info->f_sh, H5FD_MEM_DRAW, &page_buf_enabled) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't check if page buffer is enabled");
        if (page_buf_enabled) {
            io_info->use_select_io = H5D_SELECTION_IO_MODE_OFF;
            io_info->no_selection_io_cause |= H5D_SEL_IO_PAGE_BUFFER;
        }
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_may_use_select_io() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_read
 *
 * Purpose:	Read from a contiguous dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_read(H5D_io_info_t *io_info, H5D_dset_io_info_t *dinfo)
{
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(io_info);
    assert(dinfo);
    assert(dinfo->buf.vp);
    assert(dinfo->mem_space);
    assert(dinfo->file_space);

    if (io_info->use_select_io == H5D_SELECTION_IO_MODE_ON) {
        /* Only perform I/O if not performing multi dataset I/O or type conversion,
         * otherwise the higher level will handle it after all datasets
         * have been processed */
        if (H5D_LAYOUT_CB_PERFORM_IO(io_info)) {
            size_t dst_type_size = dinfo->type_info.dst_type_size;

            /* Issue selection I/O call (we can skip the page buffer because we've
             * already verified it won't be used, and the metadata accumulator
             * because this is raw data) */
            if (H5F_shared_select_read(H5F_SHARED(dinfo->dset->oloc.file), H5FD_MEM_DRAW,
                                       dinfo->nelmts > 0 ? 1 : 0, &dinfo->mem_space, &dinfo->file_space,
                                       &(dinfo->store->contig.dset_addr), &dst_type_size,
                                       &(dinfo->buf.vp)) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "contiguous selection read failed");
        }
        else {
            if (dinfo->layout_io_info.contig_piece_info) {
                /* Add to mdset selection I/O arrays */
                assert(io_info->mem_spaces);
                assert(io_info->file_spaces);
                assert(io_info->addrs);
                assert(io_info->element_sizes);
                assert(io_info->rbufs);
                assert(io_info->pieces_added < io_info->piece_count);

                io_info->mem_spaces[io_info->pieces_added]    = dinfo->mem_space;
                io_info->file_spaces[io_info->pieces_added]   = dinfo->file_space;
                io_info->addrs[io_info->pieces_added]         = dinfo->store->contig.dset_addr;
                io_info->element_sizes[io_info->pieces_added] = dinfo->type_info.src_type_size;
                io_info->rbufs[io_info->pieces_added]         = dinfo->buf.vp;
                if (io_info->sel_pieces)
                    io_info->sel_pieces[io_info->pieces_added] = dinfo->layout_io_info.contig_piece_info;
                io_info->pieces_added++;
            }
        }

#ifdef H5_HAVE_PARALLEL
        /* Report that collective contiguous I/O was used */
        io_info->actual_io_mode |= H5D_MPIO_CONTIGUOUS_COLLECTIVE;
#endif /* H5_HAVE_PARALLEL */
    }  /* end if */
    else
        /* Read data through legacy (non-selection I/O) pathway */
        if ((dinfo->io_ops.single_read)(io_info, dinfo) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "contiguous read failed");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_read() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_write
 *
 * Purpose:	Write to a contiguous dataset.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_write(H5D_io_info_t *io_info, H5D_dset_io_info_t *dinfo)
{
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(io_info);
    assert(dinfo);
    assert(dinfo->buf.cvp);
    assert(dinfo->mem_space);
    assert(dinfo->file_space);

    if (io_info->use_select_io == H5D_SELECTION_IO_MODE_ON) {
        /* Only perform I/O if not performing multi dataset I/O or type conversion,
         * otherwise the higher level will handle it after all datasets
         * have been processed */
        if (H5D_LAYOUT_CB_PERFORM_IO(io_info)) {
            size_t dst_type_size = dinfo->type_info.dst_type_size;

            /* Issue selection I/O call (we can skip the page buffer because we've
             * already verified it won't be used, and the metadata accumulator
             * because this is raw data) */
            if (H5F_shared_select_write(H5F_SHARED(dinfo->dset->oloc.file), H5FD_MEM_DRAW,
                                        dinfo->nelmts > 0 ? 1 : 0, &dinfo->mem_space, &dinfo->file_space,
                                        &(dinfo->store->contig.dset_addr), &dst_type_size,
                                        &(dinfo->buf.cvp)) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "contiguous selection write failed");
        }
        else {
            if (dinfo->layout_io_info.contig_piece_info) {
                /* Add to mdset selection I/O arrays */
                assert(io_info->mem_spaces);
                assert(io_info->file_spaces);
                assert(io_info->addrs);
                assert(io_info->element_sizes);
                assert(io_info->wbufs);
                assert(io_info->pieces_added < io_info->piece_count);

                io_info->mem_spaces[io_info->pieces_added]    = dinfo->mem_space;
                io_info->file_spaces[io_info->pieces_added]   = dinfo->file_space;
                io_info->addrs[io_info->pieces_added]         = dinfo->store->contig.dset_addr;
                io_info->element_sizes[io_info->pieces_added] = dinfo->type_info.dst_type_size;
                io_info->wbufs[io_info->pieces_added]         = dinfo->buf.cvp;
                if (io_info->sel_pieces)
                    io_info->sel_pieces[io_info->pieces_added] = dinfo->layout_io_info.contig_piece_info;
                io_info->pieces_added++;
            }
        }

#ifdef H5_HAVE_PARALLEL
        /* Report that collective contiguous I/O was used */
        io_info->actual_io_mode |= H5D_MPIO_CONTIGUOUS_COLLECTIVE;
#endif /* H5_HAVE_PARALLEL */
    }  /* end if */
    else
        /* Write data through legacy (non-selection I/O) pathway */
        if ((dinfo->io_ops.single_write)(io_info, dinfo) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "contiguous write failed");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_write() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_write_one
 *
 * Purpose:	Writes some data from a dataset into a buffer.
 *		The data is contiguous.	 The address is relative to the base
 *		address for the file.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_write_one(H5D_io_info_t *io_info, H5D_dset_io_info_t *dset_info, hsize_t offset, size_t size)
{
    hsize_t dset_off      = offset;  /* Offset in dataset */
    size_t  dset_len      = size;    /* Length in dataset */
    size_t  dset_curr_seq = 0;       /* "Current sequence" in dataset */
    hsize_t mem_off       = 0;       /* Offset in memory */
    size_t  mem_len       = size;    /* Length in memory */
    size_t  mem_curr_seq  = 0;       /* "Current sequence" in memory */
    herr_t  ret_value     = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    assert(io_info);

    if (H5D__contig_writevv(io_info, dset_info, (size_t)1, &dset_curr_seq, &dset_len, &dset_off, (size_t)1,
                            &mem_curr_seq, &mem_len, &mem_off) < 0)
        HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "vector write failed");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_write_one() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_readvv_sieve_cb
 *
 * Purpose:	Callback operator for H5D__contig_readvv() with sieve buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_readvv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len, void *_udata)
{
    H5D_contig_readvv_sieve_ud_t *udata =
        (H5D_contig_readvv_sieve_ud_t *)_udata;     /* User data for H5VM_opvv() operator */
    H5F_shared_t *f_sh        = udata->f_sh;        /* Shared file for dataset */
    H5D_rdcdc_t  *dset_contig = udata->dset_contig; /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig =
        udata->store_contig; /* Contiguous storage info for this I/O operation */
    unsigned char *buf;      /* Pointer to buffer to fill */
    haddr_t        addr;     /* Actual address to read */
    haddr_t sieve_start = HADDR_UNDEF, sieve_end = HADDR_UNDEF; /* Start & end locations of sieve buffer */
    haddr_t contig_end;                                         /* End locations of block to write */
    size_t  sieve_size = (size_t)-1;                            /* Size of sieve buffer */
    haddr_t rel_eoa;                                            /* Relative end of file address	*/
    hsize_t max_data;                                           /* Actual maximum size of data to cache */
    hsize_t min;                 /* temporary minimum value (avoids some ugly macro nesting) */
    herr_t  ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Stash local copies of these value */
    if (dset_contig->sieve_buf != NULL) {
        sieve_start = dset_contig->sieve_loc;
        sieve_size  = dset_contig->sieve_size;
        sieve_end   = sieve_start + sieve_size;
    } /* end if */

    /* Compute offset on disk */
    addr = store_contig->dset_addr + dst_off;

    /* Compute offset in memory */
    buf = udata->rbuf + src_off;

    /* Check if the sieve buffer is allocated yet */
    if (NULL == dset_contig->sieve_buf) {
        /* Check if we can actually hold the I/O request in the sieve buffer */
        if (len > dset_contig->sieve_buf_size) {
            if (H5F_shared_block_read(f_sh, H5FD_MEM_DRAW, addr, len, buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed");
        } /* end if */
        else {
            /* Allocate room for the data sieve buffer */
            if (NULL == (dset_contig->sieve_buf = H5FL_BLK_CALLOC(sieve_buf, dset_contig->sieve_buf_size)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "memory allocation failed");

            /* Determine the new sieve buffer size & location */
            dset_contig->sieve_loc = addr;

            /* Make certain we don't read off the end of the file */
            if (HADDR_UNDEF == (rel_eoa = H5F_shared_get_eoa(f_sh, H5FD_MEM_DRAW)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size");

            /* Set up the buffer parameters */
            max_data = store_contig->dset_size - dst_off;

            /* Compute the size of the sieve buffer */
            min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size);
            H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

            /* Read the new sieve buffer */
            if (H5F_shared_block_read(f_sh, H5FD_MEM_DRAW, dset_contig->sieve_loc, dset_contig->sieve_size,
                                      dset_contig->sieve_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed");

            /* Grab the data out of the buffer (must be first piece of data in buffer ) */
            H5MM_memcpy(buf, dset_contig->sieve_buf, len);

            /* Reset sieve buffer dirty flag */
            dset_contig->sieve_dirty = false;
        } /* end else */
    }     /* end if */
    else {
        /* Compute end of sequence to retrieve */
        contig_end = addr + len - 1;

        /* If entire read is within the sieve buffer, read it from the buffer */
        if (addr >= sieve_start && contig_end < sieve_end) {
            unsigned char *base_sieve_buf = dset_contig->sieve_buf + (addr - sieve_start);

            /* Grab the data out of the buffer */
            H5MM_memcpy(buf, base_sieve_buf, len);
        } /* end if */
        /* Entire request is not within this data sieve buffer */
        else {
            /* Check if we can actually hold the I/O request in the sieve buffer */
            if (len > dset_contig->sieve_buf_size) {
                /* Check for any overlap with the current sieve buffer */
                if ((sieve_start >= addr && sieve_start < (contig_end + 1)) ||
                    ((sieve_end - 1) >= addr && (sieve_end - 1) < (contig_end + 1))) {
                    /* Flush the sieve buffer, if it's dirty */
                    if (dset_contig->sieve_dirty) {
                        /* Write to file */
                        if (H5F_shared_block_write(f_sh, H5FD_MEM_DRAW, sieve_start, sieve_size,
                                                   dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");

                        /* Reset sieve buffer dirty flag */
                        dset_contig->sieve_dirty = false;
                    } /* end if */
                }     /* end if */

                /* Read directly into the user's buffer */
                if (H5F_shared_block_read(f_sh, H5FD_MEM_DRAW, addr, len, buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed");
            } /* end if */
            /* Element size fits within the buffer size */
            else {
                /* Flush the sieve buffer if it's dirty */
                if (dset_contig->sieve_dirty) {
                    /* Write to file */
                    if (H5F_shared_block_write(f_sh, H5FD_MEM_DRAW, sieve_start, sieve_size,
                                               dset_contig->sieve_buf) < 0)
                        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");

                    /* Reset sieve buffer dirty flag */
                    dset_contig->sieve_dirty = false;
                } /* end if */

                /* Determine the new sieve buffer size & location */
                dset_contig->sieve_loc = addr;

                /* Make certain we don't read off the end of the file */
                if (HADDR_UNDEF == (rel_eoa = H5F_shared_get_eoa(f_sh, H5FD_MEM_DRAW)))
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size");

                /* Only need this when resizing sieve buffer */
                max_data = store_contig->dset_size - dst_off;

                /* Compute the size of the sieve buffer.
                 * Don't read off the end of the file, don't read past
                 * the end of the data element, and don't read more than
                 * the buffer size.
                 */
                min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size);
                H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

                /* Read the new sieve buffer */
                if (H5F_shared_block_read(f_sh, H5FD_MEM_DRAW, dset_contig->sieve_loc,
                                          dset_contig->sieve_size, dset_contig->sieve_buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed");

                /* Grab the data out of the buffer (must be first piece of data in buffer ) */
                H5MM_memcpy(buf, dset_contig->sieve_buf, len);

                /* Reset sieve buffer dirty flag */
                dset_contig->sieve_dirty = false;
            } /* end else */
        }     /* end else */
    }         /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_readvv_sieve_cb() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_readvv_cb
 *
 * Purpose:	Callback operator for H5D__contig_readvv() without sieve buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_readvv_cb(hsize_t dst_off, hsize_t src_off, size_t len, void *_udata)
{
    H5D_contig_readvv_ud_t *udata = (H5D_contig_readvv_ud_t *)_udata; /* User data for H5VM_opvv() operator */
    herr_t                  ret_value = SUCCEED;                      /* Return value */

    FUNC_ENTER_PACKAGE

    /* Write data */
    if (H5F_shared_block_read(udata->f_sh, H5FD_MEM_DRAW, (udata->dset_addr + dst_off), len,
                              (udata->rbuf + src_off)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_readvv_cb() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_readvv
 *
 * Purpose:	Reads some data vectors from a dataset into a buffer.
 *		The data is contiguous.	 The address is the start of the dataset,
 *              relative to the base address for the file and the offsets and
 *              sequence lengths are in bytes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Notes:
 *      Offsets in the sequences must be monotonically increasing
 *
 *-------------------------------------------------------------------------
 */
static ssize_t
H5D__contig_readvv(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info, size_t dset_max_nseq,
                   size_t *dset_curr_seq, size_t dset_len_arr[], hsize_t dset_off_arr[], size_t mem_max_nseq,
                   size_t *mem_curr_seq, size_t mem_len_arr[], hsize_t mem_off_arr[])
{
    ssize_t ret_value = -1; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    assert(io_info);
    assert(dset_info);
    assert(dset_curr_seq);
    assert(dset_len_arr);
    assert(dset_off_arr);
    assert(mem_curr_seq);
    assert(mem_len_arr);
    assert(mem_off_arr);

    /* Check if data sieving is enabled */
    if (H5F_SHARED_HAS_FEATURE(io_info->f_sh, H5FD_FEAT_DATA_SIEVE)) {
        H5D_contig_readvv_sieve_ud_t udata; /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.f_sh         = io_info->f_sh;
        udata.dset_contig  = &(dset_info->dset->shared->cache.contig);
        udata.store_contig = &(dset_info->store->contig);
        udata.rbuf         = (unsigned char *)dset_info->buf.vp;

        /* Call generic sequence operation routine */
        if ((ret_value =
                 H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr, mem_max_nseq,
                           mem_curr_seq, mem_len_arr, mem_off_arr, H5D__contig_readvv_sieve_cb, &udata)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized sieve buffer read");
    } /* end if */
    else {
        H5D_contig_readvv_ud_t udata; /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.f_sh      = io_info->f_sh;
        udata.dset_addr = dset_info->store->contig.dset_addr;
        udata.rbuf      = (unsigned char *)dset_info->buf.vp;

        /* Call generic sequence operation routine */
        if ((ret_value = H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr, mem_max_nseq,
                                   mem_curr_seq, mem_len_arr, mem_off_arr, H5D__contig_readvv_cb, &udata)) <
            0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized read");
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_readvv() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_writevv_sieve_cb
 *
 * Purpose:	Callback operator for H5D__contig_writevv() with sieve buffer.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_writevv_sieve_cb(hsize_t dst_off, hsize_t src_off, size_t len, void *_udata)
{
    H5D_contig_writevv_sieve_ud_t *udata =
        (H5D_contig_writevv_sieve_ud_t *)_udata;    /* User data for H5VM_opvv() operator */
    H5F_shared_t *f_sh        = udata->f_sh;        /* Shared file for dataset */
    H5D_rdcdc_t  *dset_contig = udata->dset_contig; /* Cached information about contiguous data */
    const H5D_contig_storage_t *store_contig =
        udata->store_contig;   /* Contiguous storage info for this I/O operation */
    const unsigned char *buf;  /* Pointer to buffer to fill */
    haddr_t              addr; /* Actual address to read */
    haddr_t sieve_start = HADDR_UNDEF, sieve_end = HADDR_UNDEF; /* Start & end locations of sieve buffer */
    haddr_t contig_end;                                         /* End locations of block to write */
    size_t  sieve_size = (size_t)-1;                            /* size of sieve buffer */
    haddr_t rel_eoa;                                            /* Relative end of file address	*/
    hsize_t max_data;                                           /* Actual maximum size of data to cache */
    hsize_t min;                 /* temporary minimum value (avoids some ugly macro nesting) */
    herr_t  ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Stash local copies of these values */
    if (dset_contig->sieve_buf != NULL) {
        sieve_start = dset_contig->sieve_loc;
        sieve_size  = dset_contig->sieve_size;
        sieve_end   = sieve_start + sieve_size;
    } /* end if */

    /* Compute offset on disk */
    addr = store_contig->dset_addr + dst_off;

    /* Compute offset in memory */
    buf = udata->wbuf + src_off;

    /* No data sieve buffer yet, go allocate one */
    if (NULL == dset_contig->sieve_buf) {
        /* Check if we can actually hold the I/O request in the sieve buffer */
        if (len > dset_contig->sieve_buf_size) {
            if (H5F_shared_block_write(f_sh, H5FD_MEM_DRAW, addr, len, buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");
        } /* end if */
        else {
            /* Allocate room for the data sieve buffer */
            if (NULL == (dset_contig->sieve_buf = H5FL_BLK_CALLOC(sieve_buf, dset_contig->sieve_buf_size)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "memory allocation failed");

            /* Clear memory */
            if (dset_contig->sieve_size > len)
                memset(dset_contig->sieve_buf + len, 0, (dset_contig->sieve_size - len));

            /* Determine the new sieve buffer size & location */
            dset_contig->sieve_loc = addr;

            /* Make certain we don't read off the end of the file */
            if (HADDR_UNDEF == (rel_eoa = H5F_shared_get_eoa(f_sh, H5FD_MEM_DRAW)))
                HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size");

            /* Set up the buffer parameters */
            max_data = store_contig->dset_size - dst_off;

            /* Compute the size of the sieve buffer */
            min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size);
            H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

            /* Check if there is any point in reading the data from the file */
            if (dset_contig->sieve_size > len) {
                /* Read the new sieve buffer */
                if (H5F_shared_block_read(f_sh, H5FD_MEM_DRAW, dset_contig->sieve_loc,
                                          dset_contig->sieve_size, dset_contig->sieve_buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed");
            } /* end if */

            /* Grab the data out of the buffer (must be first piece of data in buffer ) */
            H5MM_memcpy(dset_contig->sieve_buf, buf, len);

            /* Set sieve buffer dirty flag */
            dset_contig->sieve_dirty = true;

            /* Stash local copies of these values */
            sieve_start = dset_contig->sieve_loc;
            sieve_size  = dset_contig->sieve_size;
            sieve_end   = sieve_start + sieve_size;
        } /* end else */
    }     /* end if */
    else {
        /* Compute end of sequence to retrieve */
        contig_end = addr + len - 1;

        /* If entire write is within the sieve buffer, write it to the buffer */
        if (addr >= sieve_start && contig_end < sieve_end) {
            unsigned char *base_sieve_buf = dset_contig->sieve_buf + (addr - sieve_start);

            /* Put the data into the sieve buffer */
            H5MM_memcpy(base_sieve_buf, buf, len);

            /* Set sieve buffer dirty flag */
            dset_contig->sieve_dirty = true;
        } /* end if */
        /* Entire request is not within this data sieve buffer */
        else {
            /* Check if we can actually hold the I/O request in the sieve buffer */
            if (len > dset_contig->sieve_buf_size) {
                /* Check for any overlap with the current sieve buffer */
                if ((sieve_start >= addr && sieve_start < (contig_end + 1)) ||
                    ((sieve_end - 1) >= addr && (sieve_end - 1) < (contig_end + 1))) {
                    /* Flush the sieve buffer, if it's dirty */
                    if (dset_contig->sieve_dirty) {
                        /* Write to file */
                        if (H5F_shared_block_write(f_sh, H5FD_MEM_DRAW, sieve_start, sieve_size,
                                                   dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");

                        /* Reset sieve buffer dirty flag */
                        dset_contig->sieve_dirty = false;
                    } /* end if */

                    /* Force the sieve buffer to be re-read the next time */
                    dset_contig->sieve_loc  = HADDR_UNDEF;
                    dset_contig->sieve_size = 0;
                } /* end if */

                /* Write directly from the user's buffer */
                if (H5F_shared_block_write(f_sh, H5FD_MEM_DRAW, addr, len, buf) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");
            } /* end if */
            /* Element size fits within the buffer size */
            else {
                /* Check if it is possible to (exactly) prepend or append to existing (dirty) sieve buffer */
                if (((addr + len) == sieve_start || addr == sieve_end) &&
                    (len + sieve_size) <= dset_contig->sieve_buf_size && dset_contig->sieve_dirty) {
                    /* Prepend to existing sieve buffer */
                    if ((addr + len) == sieve_start) {
                        /* Move existing sieve information to correct location */
                        memmove(dset_contig->sieve_buf + len, dset_contig->sieve_buf,
                                dset_contig->sieve_size);

                        /* Copy in new information (must be first in sieve buffer) */
                        H5MM_memcpy(dset_contig->sieve_buf, buf, len);

                        /* Adjust sieve location */
                        dset_contig->sieve_loc = addr;

                    } /* end if */
                    /* Append to existing sieve buffer */
                    else {
                        /* Copy in new information */
                        H5MM_memcpy(dset_contig->sieve_buf + sieve_size, buf, len);
                    } /* end else */

                    /* Adjust sieve size */
                    dset_contig->sieve_size += len;
                } /* end if */
                /* Can't add the new data onto the existing sieve buffer */
                else {
                    /* Flush the sieve buffer if it's dirty */
                    if (dset_contig->sieve_dirty) {
                        /* Write to file */
                        if (H5F_shared_block_write(f_sh, H5FD_MEM_DRAW, sieve_start, sieve_size,
                                                   dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");

                        /* Reset sieve buffer dirty flag */
                        dset_contig->sieve_dirty = false;
                    } /* end if */

                    /* Determine the new sieve buffer size & location */
                    dset_contig->sieve_loc = addr;

                    /* Make certain we don't read off the end of the file */
                    if (HADDR_UNDEF == (rel_eoa = H5F_shared_get_eoa(f_sh, H5FD_MEM_DRAW)))
                        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine file size");

                    /* Only need this when resizing sieve buffer */
                    max_data = store_contig->dset_size - dst_off;

                    /* Compute the size of the sieve buffer.
                     * Don't read off the end of the file, don't read past
                     * the end of the data element, and don't read more than
                     * the buffer size.
                     */
                    min = MIN3(rel_eoa - dset_contig->sieve_loc, max_data, dset_contig->sieve_buf_size);
                    H5_CHECKED_ASSIGN(dset_contig->sieve_size, size_t, min, hsize_t);

                    /* Check if there is any point in reading the data from the file */
                    if (dset_contig->sieve_size > len) {
                        /* Read the new sieve buffer */
                        if (H5F_shared_block_read(f_sh, H5FD_MEM_DRAW, dset_contig->sieve_loc,
                                                  dset_contig->sieve_size, dset_contig->sieve_buf) < 0)
                            HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "block read failed");
                    } /* end if */

                    /* Grab the data out of the buffer (must be first piece of data in buffer ) */
                    H5MM_memcpy(dset_contig->sieve_buf, buf, len);

                    /* Set sieve buffer dirty flag */
                    dset_contig->sieve_dirty = true;
                } /* end else */
            }     /* end else */
        }         /* end else */
    }             /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_writevv_sieve_cb() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_writevv_cb
 *
 * Purpose:	Callback operator for H5D__contig_writevv().
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_writevv_cb(hsize_t dst_off, hsize_t src_off, size_t len, void *_udata)
{
    H5D_contig_writevv_ud_t *udata =
        (H5D_contig_writevv_ud_t *)_udata; /* User data for H5VM_opvv() operator */
    herr_t ret_value = SUCCEED;            /* Return value */

    FUNC_ENTER_PACKAGE

    /* Write data */
    if (H5F_shared_block_write(udata->f_sh, H5FD_MEM_DRAW, (udata->dset_addr + dst_off), len,
                               (udata->wbuf + src_off)) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "block write failed");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_writevv_cb() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_writevv
 *
 * Purpose:	Writes some data vectors into a dataset from vectors into a
 *              buffer.  The address is the start of the dataset,
 *              relative to the base address for the file and the offsets and
 *              sequence lengths are in bytes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Notes:
 *      Offsets in the sequences must be monotonically increasing
 *
 *-------------------------------------------------------------------------
 */
static ssize_t
H5D__contig_writevv(const H5D_io_info_t *io_info, const H5D_dset_io_info_t *dset_info, size_t dset_max_nseq,
                    size_t *dset_curr_seq, size_t dset_len_arr[], hsize_t dset_off_arr[], size_t mem_max_nseq,
                    size_t *mem_curr_seq, size_t mem_len_arr[], hsize_t mem_off_arr[])
{
    ssize_t ret_value = -1; /* Return value (Size of sequence in bytes) */

    FUNC_ENTER_PACKAGE

    /* Check args */
    assert(io_info);
    assert(dset_info);
    assert(dset_curr_seq);
    assert(dset_len_arr);
    assert(dset_off_arr);
    assert(mem_curr_seq);
    assert(mem_len_arr);
    assert(mem_off_arr);

    /* Check if data sieving is enabled */
    if (H5F_SHARED_HAS_FEATURE(io_info->f_sh, H5FD_FEAT_DATA_SIEVE)) {
        H5D_contig_writevv_sieve_ud_t udata; /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.f_sh         = io_info->f_sh;
        udata.dset_contig  = &(dset_info->dset->shared->cache.contig);
        udata.store_contig = &(dset_info->store->contig);
        udata.wbuf         = (const unsigned char *)dset_info->buf.cvp;

        /* Call generic sequence operation routine */
        if ((ret_value =
                 H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr, mem_max_nseq,
                           mem_curr_seq, mem_len_arr, mem_off_arr, H5D__contig_writevv_sieve_cb, &udata)) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized sieve buffer write");
    } /* end if */
    else {
        H5D_contig_writevv_ud_t udata; /* User data for H5VM_opvv() operator */

        /* Set up user data for H5VM_opvv() */
        udata.f_sh      = io_info->f_sh;
        udata.dset_addr = dset_info->store->contig.dset_addr;
        udata.wbuf      = (const unsigned char *)dset_info->buf.cvp;

        /* Call generic sequence operation routine */
        if ((ret_value = H5VM_opvv(dset_max_nseq, dset_curr_seq, dset_len_arr, dset_off_arr, mem_max_nseq,
                                   mem_curr_seq, mem_len_arr, mem_off_arr, H5D__contig_writevv_cb, &udata)) <
            0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTOPERATE, FAIL, "can't perform vectorized read");
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_writevv() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_flush
 *
 * Purpose:	Writes all dirty data to disk.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_flush(H5D_t *dset)
{
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_PACKAGE

    /* Sanity check */
    assert(dset);

    /* Flush any data in sieve buffer */
    if (H5D__flush_sieve_buf(dset) < 0)
        HGOTO_ERROR(H5E_DATASET, H5E_CANTFLUSH, FAIL, "unable to flush sieve buffer");

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_flush() */

/*-------------------------------------------------------------------------
 * Function:    H5D__contig_io_term
 *
 * Purpose:    Destroy I/O operation information.
 *
 * Return:    Non-negative on success/Negative on failure
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5D__contig_io_term(H5D_io_info_t H5_ATTR_UNUSED *io_info, H5D_dset_io_info_t *di)
{
    herr_t ret_value = SUCCEED; /*return value        */

    FUNC_ENTER_PACKAGE

    assert(di);

    /* Free piece info */
    if (di->layout_io_info.contig_piece_info) {
        if (H5D__free_piece_info(di->layout_io_info.contig_piece_info, NULL, NULL) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "can't free piece info");
        di->layout_io_info.contig_piece_info = NULL;
    }

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_io_term() */

/*-------------------------------------------------------------------------
 * Function:	H5D__contig_copy
 *
 * Purpose:	Copy contiguous storage raw data from SRC file to DST file.
 *
 * Return:	Non-negative on success, negative on failure.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5D__contig_copy(H5F_t *f_src, const H5O_storage_contig_t *storage_src, H5F_t *f_dst,
                 H5O_storage_contig_t *storage_dst, H5T_t *dt_src, H5O_copy_t *cpy_info)
{
    haddr_t       addr_src;                                    /* File offset in source dataset */
    haddr_t       addr_dst;                                    /* File offset in destination dataset */
    H5T_path_t   *tpath_src_mem = NULL, *tpath_mem_dst = NULL; /* Datatype conversion paths */
    H5T_t        *dt_dst      = NULL;                          /* Destination datatype */
    H5T_t        *dt_mem      = NULL;                          /* Memory datatype */
    size_t        src_dt_size = 0;                             /* Source datatype size */
    size_t        mem_dt_size = 0;                             /* Memory datatype size */
    size_t        dst_dt_size = 0;                             /* Destination datatype size */
    size_t        max_dt_size;                                 /* Max. datatype size */
    size_t        nelmts = 0;                                  /* Number of elements in buffer */
    size_t        src_nbytes;                                  /* Number of bytes to read from source */
    size_t        mem_nbytes;                                  /* Number of bytes to convert in memory */
    size_t        dst_nbytes;                                  /* Number of bytes to write to destination */
    hsize_t       total_src_nbytes;                            /* Total number of bytes to copy */
    size_t        buf_size;                                    /* Size of copy buffer */
    void         *buf         = NULL;                          /* Buffer for copying data */
    void         *bkg         = NULL;                          /* Temporary buffer for copying data */
    void         *reclaim_buf = NULL;                          /* Buffer for reclaiming data */
    H5S_t        *buf_space   = NULL;                          /* Dataspace describing buffer */
    hid_t         buf_sid     = -1;                            /* ID for buffer dataspace */
    hsize_t       buf_dim[1]  = {0};                           /* Dimension for buffer */
    bool          is_vlen     = false; /* Flag to indicate that VL type conversion should occur */
    bool          fix_ref     = false; /* Flag to indicate that ref values should be fixed */
    H5D_shared_t *shared_fo =
        (H5D_shared_t *)cpy_info->shared_fo; /* Pointer to the shared struct for dataset object */
    bool    try_sieve   = false;             /* Try to get data from the sieve buffer */
    haddr_t sieve_start = HADDR_UNDEF;       /* Start location of sieve buffer */
    haddr_t sieve_end   = HADDR_UNDEF;       /* End locations of sieve buffer */
    herr_t  ret_value   = SUCCEED;           /* Return value */

    FUNC_ENTER_PACKAGE

    /* Check args */
    assert(f_src);
    assert(storage_src);
    assert(f_dst);
    assert(storage_dst);
    assert(dt_src);

    /* Allocate space for destination raw data */
    if (H5D__contig_alloc(f_dst, storage_dst) < 0)
        HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to allocate contiguous storage");

    /* Set up number of bytes to copy, and initial buffer size */
    /* (actually use the destination size, which has been fixed up, if necessary) */
    total_src_nbytes = storage_dst->size;
    H5_CHECK_OVERFLOW(total_src_nbytes, hsize_t, size_t);
    buf_size = MIN(H5D_TEMP_BUF_SIZE, (size_t)total_src_nbytes);

    /* If there's a VLEN source datatype, set up type conversion information */
    if (H5T_detect_class(dt_src, H5T_VLEN, false) > 0) {
        /* create a memory copy of the variable-length datatype */
        if (NULL == (dt_mem = H5T_copy(dt_src, H5T_COPY_TRANSIENT)))
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to copy");

        /* create variable-length datatype at the destination file */
        if (NULL == (dt_dst = H5T_copy(dt_src, H5T_COPY_TRANSIENT)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to copy");
        if (H5T_set_loc(dt_dst, H5F_VOL_OBJ(f_dst), H5T_LOC_DISK) < 0) {
            (void)H5T_close_real(dt_dst);
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "cannot mark datatype on disk");
        } /* end if */

        /* Set up the conversion functions */
        if (NULL == (tpath_src_mem = H5T_path_find(dt_src, dt_mem)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to convert between src and mem datatypes");
        if (NULL == (tpath_mem_dst = H5T_path_find(dt_mem, dt_dst)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to convert between mem and dst datatypes");

        /* Determine largest datatype size */
        if (0 == (src_dt_size = H5T_get_size(dt_src)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to determine datatype size");
        if (0 == (mem_dt_size = H5T_get_size(dt_mem)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to determine datatype size");
        max_dt_size = MAX(src_dt_size, mem_dt_size);
        if (0 == (dst_dt_size = H5T_get_size(dt_dst)))
            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to determine datatype size");
        max_dt_size = MAX(max_dt_size, dst_dt_size);

        /* Set maximum number of whole elements that fit in buffer */
        if (0 == (nelmts = buf_size / max_dt_size))
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "element size too large");

        /* Set the number of bytes to transfer */
        src_nbytes = nelmts * src_dt_size;
        dst_nbytes = nelmts * dst_dt_size;
        mem_nbytes = nelmts * mem_dt_size;

        /* Adjust buffer size to be multiple of elements */
        buf_size = nelmts * max_dt_size;

        /* Create dataspace for number of elements in buffer */
        buf_dim[0] = nelmts;

        /* Create the space and set the initial extent */
        if (NULL == (buf_space = H5S_create_simple((unsigned)1, buf_dim, NULL)))
            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCREATE, FAIL, "can't create simple dataspace");

        /* Register */
        if ((buf_sid = H5I_register(H5I_DATASPACE, buf_space, false)) < 0) {
            H5S_close(buf_space);
            HGOTO_ERROR(H5E_ID, H5E_CANTREGISTER, FAIL, "unable to register dataspace ID");
        } /* end if */

        /* Set flag to do type conversion */
        is_vlen = true;
    } /* end if */
    else {
        /* Check for reference datatype */
        if (H5T_get_class(dt_src, false) == H5T_REFERENCE) {
            /* Need to fix values of references when copying across files */
            if (f_src != f_dst)
                fix_ref = true;
        } /* end if */

        /* Set the number of bytes to read & write to the buffer size */
        src_nbytes = dst_nbytes = mem_nbytes = buf_size;
    } /* end else */

    /* Allocate space for copy buffer */
    assert(buf_size);
    if (NULL == (buf = H5FL_BLK_MALLOC(type_conv, buf_size)))
        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for copy buffer");

    /* Need extra buffer for datatype conversions, to prevent stranding/leaking memory */
    if (is_vlen || fix_ref) {
        if (NULL == (reclaim_buf = H5FL_BLK_MALLOC(type_conv, buf_size)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for copy buffer");

        /* allocate temporary bkg buff for data conversion */
        if (NULL == (bkg = H5FL_BLK_MALLOC(type_conv, buf_size)))
            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for copy buffer");
    } /* end if */

    /* Loop over copying data */
    addr_src = storage_src->addr;
    addr_dst = storage_dst->addr;

    /* If data sieving is enabled and the dataset is open in the file,
       set up to copy data out of the sieve buffer if deemed possible later */
    if (H5F_HAS_FEATURE(f_src, H5FD_FEAT_DATA_SIEVE) && shared_fo && shared_fo->cache.contig.sieve_buf) {
        try_sieve   = true;
        sieve_start = shared_fo->cache.contig.sieve_loc;
        sieve_end   = sieve_start + shared_fo->cache.contig.sieve_size;
    }

    while (total_src_nbytes > 0) {
        /* Check if we should reduce the number of bytes to transfer */
        if (total_src_nbytes < src_nbytes) {
            /* Adjust bytes to transfer */
            src_nbytes = (size_t)total_src_nbytes;

            /* Adjust dataspace describing buffer */
            if (is_vlen) {
                /* Adjust destination & memory bytes to transfer */
                nelmts     = src_nbytes / src_dt_size;
                dst_nbytes = nelmts * dst_dt_size;
                mem_nbytes = nelmts * mem_dt_size;

                /* Adjust size of buffer's dataspace dimension */
                buf_dim[0] = nelmts;

                /* Adjust size of buffer's dataspace */
                if (H5S_set_extent_real(buf_space, buf_dim) < 0)
                    HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSET, FAIL, "unable to change buffer dataspace size");
            } /* end if */
            else
                /* Adjust destination & memory bytes to transfer */
                dst_nbytes = mem_nbytes = src_nbytes;
        } /* end if */

        /* If the entire copy is within the sieve buffer, copy data from the sieve buffer */
        if (try_sieve && (addr_src >= sieve_start) && ((addr_src + src_nbytes - 1) < sieve_end)) {
            unsigned char *base_sieve_buf = shared_fo->cache.contig.sieve_buf + (addr_src - sieve_start);

            H5MM_memcpy(buf, base_sieve_buf, src_nbytes);
        }
        else
            /* Read raw data from source file */
            if (H5F_block_read(f_src, H5FD_MEM_DRAW, addr_src, src_nbytes, buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "unable to read raw data");

        /* Perform datatype conversion, if necessary */
        if (is_vlen) {
            /* Convert from source file to memory */
            if (H5T_convert(tpath_src_mem, dt_src, dt_mem, nelmts, (size_t)0, (size_t)0, buf, bkg) < 0)
                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCONVERT, FAIL, "datatype conversion failed");

            /* Copy into another buffer, to reclaim memory later */
            H5MM_memcpy(reclaim_buf, buf, mem_nbytes);

            /* Set background buffer to all zeros */
            memset(bkg, 0, buf_size);

            /* Convert from memory to destination file */
            if (H5T_convert(tpath_mem_dst, dt_mem, dt_dst, nelmts, (size_t)0, (size_t)0, buf, bkg) < 0)
                HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCONVERT, FAIL, "datatype conversion failed");

            /* Reclaim space from variable length data */
            if (H5T_reclaim(dt_mem, buf_space, reclaim_buf) < 0)
                HGOTO_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "unable to reclaim variable-length data");
        } /* end if */
        else if (fix_ref) {
            /* Check for expanding references */
            if (cpy_info->expand_ref) {
                /* Copy the reference elements */
                if (H5O_copy_expand_ref(f_src, dt_src, buf, buf_size, f_dst, bkg, cpy_info) < 0)
                    HGOTO_ERROR(H5E_DATASET, H5E_CANTCOPY, FAIL, "unable to copy reference attribute");

                /* After fix ref, copy the new reference elements to the buffer to write out */
                H5MM_memcpy(buf, bkg, buf_size);
            } /* end if */
            else
                /* Reset value to zero */
                memset(buf, 0, src_nbytes);
        } /* end if */

        /* Write raw data to destination file */
        if (H5F_block_write(f_dst, H5FD_MEM_DRAW, addr_dst, dst_nbytes, buf) < 0)
            HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "unable to write raw data");

        /* Adjust loop variables */
        addr_src += src_nbytes;
        addr_dst += dst_nbytes;
        total_src_nbytes -= src_nbytes;
    } /* end while */

done:
    if (buf_sid > 0 && H5I_dec_ref(buf_sid) < 0)
        HDONE_ERROR(H5E_DATASET, H5E_CANTFREE, FAIL, "can't decrement temporary dataspace ID");
    /* Caller expects that source datatype will be freed */
    if (dt_src && (H5T_close(dt_src) < 0))
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "can't close temporary datatype");
    if (dt_dst && (H5T_close(dt_dst) < 0))
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "can't close temporary datatype");
    if (dt_mem && (H5T_close(dt_mem) < 0))
        HDONE_ERROR(H5E_DATASET, H5E_CANTCLOSEOBJ, FAIL, "can't close temporary datatype");
    if (buf)
        buf = H5FL_BLK_FREE(type_conv, buf);
    if (reclaim_buf)
        reclaim_buf = H5FL_BLK_FREE(type_conv, reclaim_buf);
    if (bkg)
        bkg = H5FL_BLK_FREE(type_conv, bkg);

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5D__contig_copy() */