hdf5/src/H5HFhdr.c

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Copyright by The HDF Group.                                               *
 * 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://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
 * access to either file, you may request a copy from help@hdfgroup.org.     *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*-------------------------------------------------------------------------
 *
 * Created:		H5HFhdr.c
 *			Apr 10 2006
 *			Quincey Koziol <koziol@ncsa.uiuc.edu>
 *
 * Purpose:		Heap header routines for fractal heaps.
 *
 *-------------------------------------------------------------------------
 */

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

#include "H5HFmodule.h"         /* This source code file is part of the H5HF module */


/***********/
/* Headers */
/***********/
#include "H5private.h"		/* Generic Functions			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5HFpkg.h"		/* Fractal heaps			*/
#include "H5MFprivate.h"	/* File memory management		*/
#include "H5VMprivate.h"		/* Vectors and arrays 			*/

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

#ifndef NDEBUG
/* Limit on the size of the max. direct block size */
/* (This is limited to 32-bits currently, because I think it's unlikely to
 *      need to be larger, the 32-bit limit for H5VM_log2_of2(n), and
 *      some offsets/sizes are encoded with a maxiumum of 32-bits  - QAK)
 */
#define H5HF_MAX_DIRECT_SIZE_LIMIT ((hsize_t)2 * 1024 * 1024 * 1024)

/* Limit on the width of the doubling table */
/* (This is limited to 16-bits currently, because I think it's unlikely to
 *      need to be larger, and its encoded with a maxiumum of 16-bits  - QAK)
 */
#define H5HF_WIDTH_LIMIT (64 * 1024)
#endif /* NDEBUG */


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


/********************/
/* Package Typedefs */
/********************/


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


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

/* Declare a free list to manage the H5HF_hdr_t struct */
H5FL_DEFINE_STATIC(H5HF_hdr_t);


/*****************************/
/* Library Private Variables */
/*****************************/


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



/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_alloc
 *
 * Purpose:	Allocate shared fractal heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 21 2006
 *
 *-------------------------------------------------------------------------
 */
H5HF_hdr_t *
H5HF_hdr_alloc(H5F_t *f)
{
    H5HF_hdr_t *hdr = NULL;          /* Shared fractal heap header */
    H5HF_hdr_t *ret_value = NULL;    /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(f);

    /* Allocate space for the shared information */
    if(NULL == (hdr = H5FL_CALLOC(H5HF_hdr_t)))
	HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "allocation failed for fractal heap shared header")

    /* Set the internal parameters for the heap */
    hdr->f = f;
    hdr->sizeof_size = H5F_SIZEOF_SIZE(f);
    hdr->sizeof_addr = H5F_SIZEOF_ADDR(f);

    /* Set the return value */
    ret_value = hdr;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_alloc() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_free_space
 *
 * Purpose:	Compute direct block free space, for indirect blocks of
 *              different sizes.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 21 2006
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5HF_hdr_compute_free_space(H5HF_hdr_t *hdr, unsigned iblock_row)
{
    hsize_t acc_heap_size;      /* Accumumated heap space */
    hsize_t iblock_size;        /* Size of indirect block to calculate for */
    hsize_t acc_dblock_free;    /* Accumumated direct block free space */
    size_t max_dblock_free;     /* Max. direct block free space */
    unsigned curr_row;          /* Current row in block */
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(iblock_row >= hdr->man_dtable.max_direct_rows);

    /* Set the free space in direct blocks */
    acc_heap_size = 0;
    acc_dblock_free = 0;
    max_dblock_free = 0;
    iblock_size = hdr->man_dtable.row_block_size[iblock_row];
    curr_row = 0;
    while(acc_heap_size < iblock_size) {
        acc_heap_size += hdr->man_dtable.row_block_size[curr_row] *
                hdr->man_dtable.cparam.width;
        acc_dblock_free += hdr->man_dtable.row_tot_dblock_free[curr_row] *
                hdr->man_dtable.cparam.width;
        if(hdr->man_dtable.row_max_dblock_free[curr_row] > max_dblock_free)
            max_dblock_free = hdr->man_dtable.row_max_dblock_free[curr_row];
        curr_row++;
    } /* end while */

    /* Set direct block free space values for indirect block */
    hdr->man_dtable.row_tot_dblock_free[iblock_row] = acc_dblock_free;
    hdr->man_dtable.row_max_dblock_free[iblock_row] = max_dblock_free;

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_compute_free_space() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_finish_init_phase1
 *
 * Purpose:	First phase to finish initializing info in shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@hdfgroup.org
 *		Aug 12 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_finish_init_phase1(H5HF_hdr_t *hdr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Compute/cache some values */
    hdr->heap_off_size = (uint8_t)H5HF_SIZEOF_OFFSET_BITS(hdr->man_dtable.cparam.max_index);
    if(H5HF_dtable_init(&hdr->man_dtable) < 0)
	HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't initialize doubling table info")

    /* Set the size of heap IDs */
    hdr->heap_len_size = (uint8_t)MIN(hdr->man_dtable.max_dir_blk_off_size,
            H5VM_limit_enc_size((uint64_t)hdr->max_man_size));

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_finish_init_phase1() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_finish_init_phase2
 *
 * Purpose:	Second phase to finish initializing info in shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@hdfgroup.org
 *		Aug 12 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_finish_init_phase2(H5HF_hdr_t *hdr)
{
    unsigned u;                         /* Local index variable */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Set the free space in direct blocks */
    for(u = 0; u < hdr->man_dtable.max_root_rows; u++) {
        if(u < hdr->man_dtable.max_direct_rows) {
            hdr->man_dtable.row_tot_dblock_free[u] = hdr->man_dtable.row_block_size[u] -
                    H5HF_MAN_ABS_DIRECT_OVERHEAD(hdr);
            H5_CHECKED_ASSIGN(hdr->man_dtable.row_max_dblock_free[u], size_t, hdr->man_dtable.row_tot_dblock_free[u], hsize_t);
        } /* end if */
        else
            if(H5HF_hdr_compute_free_space(hdr, u) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't initialize direct block free space for indirect block")
    } /* end for */

    /* Initialize the block iterator for searching for free space */
    if(H5HF_man_iter_init(&hdr->next_block) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't initialize space search block iterator")

    /* Initialize the information for tracking 'huge' objects */
    if(H5HF_huge_init(hdr) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't initialize info for tracking huge objects")

    /* Initialize the information for tracking 'tiny' objects */
    if(H5HF_tiny_init(hdr) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't initialize info for tracking tiny objects")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_finish_init_phase2() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_finish_init
 *
 * Purpose:	Finish initializing info in shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 21 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_finish_init(H5HF_hdr_t *hdr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* First phase of header final initialization */
    if(H5HF_hdr_finish_init_phase1(hdr) < 0)
	HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't finish phase #1 of header final initialization")

    /* Second phase of header final initialization */
    if(H5HF_hdr_finish_init_phase2(hdr) < 0)
	HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't finish phase #2 of header final initialization")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_finish_init() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_create
 *
 * Purpose:	Create new fractal heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 21 2006
 *
 *-------------------------------------------------------------------------
 */
haddr_t
H5HF_hdr_create(H5F_t *f, hid_t dxpl_id, const H5HF_create_t *cparam)
{
    H5HF_hdr_t *hdr = NULL;     /* The new fractal heap header information */
    size_t dblock_overhead;     /* Direct block's overhead */
    haddr_t ret_value = HADDR_UNDEF;    /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(f);
    HDassert(cparam);

#ifndef NDEBUG
    /* Check for valid parameters */
    if(cparam->managed.width == 0)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "width must be greater than zero")
    if(cparam->managed.width > H5HF_WIDTH_LIMIT)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "width too large")
    if(!POWER_OF_TWO(cparam->managed.width))
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "width not power of two")
    if(cparam->managed.start_block_size == 0)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "starting block size must be greater than zero")
    if(!POWER_OF_TWO(cparam->managed.start_block_size))
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "starting block size not power of two")
    if(cparam->managed.max_direct_size == 0)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. direct block size must be greater than zero")
    if(cparam->managed.max_direct_size > H5HF_MAX_DIRECT_SIZE_LIMIT)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. direct block size too large")
    if(!POWER_OF_TWO(cparam->managed.max_direct_size))
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. direct block size not power of two")
    if(cparam->managed.max_direct_size < cparam->max_man_size)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. direct block size not large enough to hold all managed blocks")
    if(cparam->managed.max_index == 0)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. heap size must be greater than zero")
#endif /* NDEBUG */

    /* Allocate & basic initialization for the shared header */
    if(NULL == (hdr = H5HF_hdr_alloc(f)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, HADDR_UNDEF, "can't allocate space for shared heap info")

#ifndef NDEBUG
    if(cparam->managed.max_index > (unsigned)(8 * hdr->sizeof_size))
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. heap size too large for file")
#endif /* NDEBUG */

    /* Set the creation parameters for the heap */
    hdr->max_man_size = cparam->max_man_size;
    hdr->checksum_dblocks = cparam->checksum_dblocks;
    HDmemcpy(&(hdr->man_dtable.cparam), &(cparam->managed), sizeof(H5HF_dtable_cparam_t));

    /* Set root table address to indicate that the heap is empty currently */
    hdr->man_dtable.table_addr = HADDR_UNDEF;

    /* Set free list header address to indicate that the heap is empty currently */
    hdr->fs_addr = HADDR_UNDEF;

    /* Set "huge" object tracker v2 B-tree address to indicate that there aren't any yet */
    hdr->huge_bt2_addr = HADDR_UNDEF;

    /* First phase of header final initialization */
    /* (doesn't need ID length set up) */
    if(H5HF_hdr_finish_init_phase1(hdr) < 0)
	HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, HADDR_UNDEF, "can't finish phase #1 of header final initialization")

    /* Copy any I/O filter pipeline */
    /* (This code is not in the "finish init phase" routines because those
     *  routines are also called from the cache 'load' callback, and the filter
     *  length is already set in that case (its stored in the header on disk))
     */
    if(cparam->pline.nused > 0) {
        /* Check if the filters in the DCPL can be applied to this dataset */
        if(H5Z_can_apply_direct(&(cparam->pline)) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, HADDR_UNDEF, "I/O filters can't operate on this heap")

        /* Mark the filters as checked */
        hdr->checked_filters = TRUE;

        /* Make the "set local" filter callbacks for this dataset */
        if(H5Z_set_local_direct(&(cparam->pline)) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, HADDR_UNDEF, "unable to set local filter parameters")

        /* Copy the I/O filter pipeline from the creation parameters to the header */
        if(NULL == H5O_msg_copy(H5O_PLINE_ID, &(cparam->pline), &(hdr->pline)))
            HGOTO_ERROR(H5E_HEAP, H5E_CANTCOPY, HADDR_UNDEF, "can't copy I/O filter pipeline")

        /* Pay attention to the latest version flag for the file */
        if(H5F_USE_LATEST_FLAGS(hdr->f, H5F_LATEST_PLINE_MSG))
            /* Set the latest version for the I/O pipeline message */
            if(H5O_pline_set_latest_version(&(hdr->pline)) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTSET, HADDR_UNDEF, "can't set latest version of I/O filter pipeline")

        /* Compute the I/O filters' encoded size */
        if(0 == (hdr->filter_len = (unsigned)H5O_msg_raw_size(hdr->f, H5O_PLINE_ID, FALSE, &(hdr->pline))))
            HGOTO_ERROR(H5E_HEAP, H5E_CANTGETSIZE, HADDR_UNDEF, "can't get I/O filter pipeline size")

        /* Compute size of header on disk */
        hdr->heap_size = H5HF_HEADER_SIZE(hdr)  /* Base header size */
            + hdr->sizeof_size                  /* Size of size for filtered root direct block */
            + 4                                 /* Size of filter mask for filtered root direct block */
            + hdr->filter_len;                  /* Size of encoded I/O filter info */
    } /* end if */
    else {
        /* Set size of header on disk */
        hdr->heap_size = H5HF_HEADER_SIZE(hdr);

        /* Mark filters as checked, for performance reasons */
        hdr->checked_filters = TRUE;
    } /* end else */

    /* Set the length of IDs in the heap */
    /* (This code is not in the "finish init phase" routines because those
     *  routines are also called from the cache 'load' callback, and the ID
     *  length is already set in that case (its stored in the header on disk))
     */
    switch(cparam->id_len) {
        case 0: /* Set the length of heap IDs to just enough to hold the offset & length of 'normal' objects in the heap */
            hdr->id_len = (unsigned)1 + hdr->heap_off_size + hdr->heap_len_size;
            break;

        case 1: /* Set the length of heap IDs to just enough to hold the information needed to directly access 'huge' objects in the heap */
            if(hdr->filter_len > 0)
                hdr->id_len = (unsigned)1 /* ID flags */
                    + hdr->sizeof_addr  /* Address of filtered object */
                    + hdr->sizeof_size  /* Length of filtered object */
                    + 4                 /* Filter mask for filtered object */
                    + hdr->sizeof_size; /* Size of de-filtered object in memory */
            else
                hdr->id_len = (unsigned)1 /* ID flags */
                    + hdr->sizeof_addr  /* Address of object */
                    + hdr->sizeof_size; /* Length of object */
            break;

        default:    /* Use the requested size for the heap ID */
            /* Check boundaries */
            if(cparam->id_len < (1 + hdr->heap_off_size + hdr->heap_len_size))
                HGOTO_ERROR(H5E_HEAP, H5E_BADRANGE, HADDR_UNDEF, "ID length not large enough to hold object IDs")
            else if(cparam->id_len > H5HF_MAX_ID_LEN)
                HGOTO_ERROR(H5E_HEAP, H5E_BADRANGE, HADDR_UNDEF, "ID length too large to store tiny object lengths")

            /* Use the requested size for the heap ID */
            hdr->id_len = cparam->id_len;
            break;
    } /* end switch */

    /* Second phase of header final initialization */
    /* (needs ID and filter lengths set up) */
    if(H5HF_hdr_finish_init_phase2(hdr) < 0)
	HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, HADDR_UNDEF, "can't finish phase #2 of header final initialization")

    /* Extra checking for possible gap between max. direct block size minus
     * overhead and "huge" object size */
    dblock_overhead = H5HF_MAN_ABS_DIRECT_OVERHEAD(hdr);
    if((cparam->managed.max_direct_size - dblock_overhead) < cparam->max_man_size)
	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, HADDR_UNDEF, "max. direct block size not large enough to hold all managed blocks")

    /* Allocate space for the header on disk */
    if(HADDR_UNDEF == (hdr->heap_addr = H5MF_alloc(f, H5FD_MEM_FHEAP_HDR, dxpl_id, (hsize_t)hdr->heap_size)))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, HADDR_UNDEF, "file allocation failed for fractal heap header")

    /* Cache the new fractal heap header */
    if(H5AC_insert_entry(f, dxpl_id, H5AC_FHEAP_HDR, hdr->heap_addr, hdr, H5AC__NO_FLAGS_SET) < 0)
	HGOTO_ERROR(H5E_HEAP, H5E_CANTINSERT, HADDR_UNDEF, "can't add fractal heap header to cache")

    /* Set address of heap header to return */
    ret_value = hdr->heap_addr;

done:
    if(!H5F_addr_defined(ret_value) && hdr)
        if(H5HF_hdr_free(hdr) < 0)
            HDONE_ERROR(H5E_HEAP, H5E_CANTRELEASE, HADDR_UNDEF, "unable to release fractal heap header")

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_create() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_protect
 *
 * Purpose:	Convenience wrapper around H5AC_protect on an indirect block
 *
 * Return:	Pointer to indirect block on success, NULL on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@hdfgroup.org
 *		May  5 2010
 *
 *-------------------------------------------------------------------------
 */
H5HF_hdr_t *
H5HF_hdr_protect(H5F_t *f, hid_t dxpl_id, haddr_t addr, unsigned flags)
{
    H5HF_hdr_cache_ud_t cache_udata;    /* User-data for callback */
    H5HF_hdr_t *hdr;                    /* Fractal heap header */
    H5HF_hdr_t *ret_value = NULL;       /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Check arguments */
    HDassert(f);
    HDassert(H5F_addr_defined(addr));

    /* only H5AC__READ_ONLY_FLAG may appear in flags */
    HDassert((flags & (unsigned)(~H5AC__READ_ONLY_FLAG)) == 0);

    /* Set up userdata for protect call */
    cache_udata.f = f;
    cache_udata.dxpl_id = dxpl_id;

    /* Lock the heap header into memory */
    if(NULL == (hdr = (H5HF_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_FHEAP_HDR, addr, &cache_udata, flags)))
        HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap header")

    /* Set the header's address */
    hdr->heap_addr = addr;

    /* Update header's file pointer */
    hdr->f = f;

    /* Set the return value */
    ret_value = hdr;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_protect() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_incr
 *
 * Purpose:	Increment component reference count on shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 27 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_incr(H5HF_hdr_t *hdr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Sanity check */
    HDassert(hdr);

    /* Mark header as un-evictable when a block is depending on it */
    if(hdr->rc == 0)
        if(H5AC_pin_protected_entry(hdr) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTPIN, FAIL, "unable to pin fractal heap header")

    /* Increment reference count on shared header */
    hdr->rc++;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_incr() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_decr
 *
 * Purpose:	Decrement component reference count on shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 27 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_decr(H5HF_hdr_t *hdr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Sanity check */
    HDassert(hdr);
    HDassert(hdr->rc);

    /* Decrement reference count on shared header */
    hdr->rc--;

    /* Mark header as evictable again when no child blocks depend on it */
    if(hdr->rc == 0) {
        HDassert(hdr->file_rc == 0);
        if(H5AC_unpin_entry(hdr) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTUNPIN, FAIL, "unable to unpin fractal heap header")
    } /* end if */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_decr() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_fuse_incr
 *
 * Purpose:	Increment file reference count on shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Oct  1 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_fuse_incr(H5HF_hdr_t *hdr)
{
    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /* Sanity check */
    HDassert(hdr);

    /* Increment file reference count on shared header */
    hdr->file_rc++;

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5HF_hdr_fuse_incr() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_fuse_decr
 *
 * Purpose:	Decrement file reference count on shared heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Oct  1 2006
 *
 *-------------------------------------------------------------------------
 */
size_t
H5HF_hdr_fuse_decr(H5HF_hdr_t *hdr)
{
    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /* Sanity check */
    HDassert(hdr);
    HDassert(hdr->file_rc);

    /* Decrement file reference count on shared header */
    hdr->file_rc--;

    FUNC_LEAVE_NOAPI(hdr->file_rc)
} /* end H5HF_hdr_fuse_decr() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_dirty
 *
 * Purpose:	Mark heap header as dirty
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 27 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_dirty(H5HF_hdr_t *hdr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Sanity check */
    HDassert(hdr);

    /* Resize pinned header in cache if I/O filter is present. */
    if(hdr->filter_len > 0) {
        if(H5AC_resize_entry(hdr, (size_t)hdr->heap_size) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTRESIZE, FAIL, "unable to resize fractal heap header")
    } /* end if */

    /* Mark header as dirty in cache */
    if(H5AC_mark_entry_dirty(hdr) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTMARKDIRTY, FAIL, "unable to mark fractal heap header as dirty")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_dirty() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_adj_free
 *
 * Purpose:	Adjust the free space for a heap
 *
 * Return:	SUCCEED/FAIL
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May  9 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_adj_free(H5HF_hdr_t *hdr, ssize_t amt)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Update heap header */
    HDassert(amt > 0 || hdr->total_man_free >= (hsize_t)-amt);
    hdr->total_man_free = (hsize_t)((hssize_t)hdr->total_man_free + amt);

    /* Mark heap header as modified */
    if(H5HF_hdr_dirty(hdr) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_adj_free() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_adjust_heap
 *
 * Purpose:	Adjust heap space
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Apr 10 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_adjust_heap(H5HF_hdr_t *hdr, hsize_t new_size, hssize_t extra_free)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Set the total managed space in heap */
    hdr->man_size = new_size;

    /* Adjust the free space in direct blocks */
    HDassert(extra_free > 0 || hdr->total_man_free >= (hsize_t)-extra_free);
    hdr->total_man_free = (hsize_t)((hssize_t)hdr->total_man_free + extra_free);

    /* Mark heap header as modified */
    if(H5HF_hdr_dirty(hdr) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark header as dirty")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_adjust_heap() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_inc_alloc
 *
 * Purpose:	Increase allocated size of heap
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May 23 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_inc_alloc(H5HF_hdr_t *hdr, size_t alloc_size)
{
    FUNC_ENTER_NOAPI_NOINIT_NOERR

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(alloc_size);

    /* Update the "allocated" size within the heap */
    hdr->man_alloc_size += alloc_size;

    FUNC_LEAVE_NOAPI(SUCCEED)
} /* end H5HF_hdr_inc_alloc() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_start_iter
 *
 * Purpose:	Start "next block" iterator at an offset/entry in the heap
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May 30 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_start_iter(H5HF_hdr_t *hdr, H5HF_indirect_t *iblock, hsize_t curr_off, unsigned curr_entry)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(iblock);

    /* Set up "next block" iterator at correct location */
    if(H5HF_man_iter_start_entry(hdr, &hdr->next_block, iblock, curr_entry) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't initialize block iterator")

    /* Set the offset of the iterator in the heap */
    hdr->man_iter_off = curr_off;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_start_iter() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_reset_iter
 *
 * Purpose:	Reset "next block" iterator
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May 31 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_reset_iter(H5HF_hdr_t *hdr, hsize_t curr_off)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Reset "next block" iterator */
    if(H5HF_man_iter_reset(&hdr->next_block) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTRELEASE, FAIL, "can't reset block iterator")

    /* Set the offset of the iterator in the heap */
    hdr->man_iter_off = curr_off;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_reset_iter() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_skip_blocks
 *
 * Purpose:	Add skipped direct blocks to free space for heap
 *
 * Return:	SUCCEED/FAIL
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Apr  3 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_skip_blocks(H5HF_hdr_t *hdr, hid_t dxpl_id, H5HF_indirect_t *iblock,
    unsigned start_entry, unsigned nentries)
{
    unsigned row, col;                  /* Row & column of entry */
    hsize_t sect_size;                  /* Size of section in heap space */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(iblock);
    HDassert(nentries);

    /* Compute the span within the heap to skip */
    row = start_entry / hdr->man_dtable.cparam.width;
    col = start_entry % hdr->man_dtable.cparam.width;
    sect_size = H5HF_dtable_span_size(&hdr->man_dtable, row, col, nentries);
    HDassert(sect_size > 0);

    /* Advance the new block iterator */
    if(H5HF_hdr_inc_iter(hdr, sect_size, nentries) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTRELEASE, FAIL, "can't increase allocated heap size")

    /* Add 'indirect' section for blocks skipped in this row */
    if(H5HF_sect_indirect_add(hdr, dxpl_id, iblock, start_entry, nentries) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't create indirect section for indirect block's free space")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_skip_blocks() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_update_iter
 *
 * Purpose:	Update state of heap to account for current iterator
 *              position.
 *
 * Note:	Creates necessary indirect blocks
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 14 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_update_iter(H5HF_hdr_t *hdr, hid_t dxpl_id, size_t min_dblock_size)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(min_dblock_size > 0);

    /* Check for creating first indirect block */
    if(hdr->man_dtable.curr_root_rows == 0) {
        if(H5HF_man_iblock_root_create(hdr, dxpl_id, min_dblock_size) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTEXTEND, FAIL, "unable to create root indirect block")
    } /* end if */
    else {
        H5HF_indirect_t *iblock;        /* Pointer to indirect block */
        hbool_t walked_up, walked_down; /* Condition variables for finding direct block location */
        unsigned next_row;              /* Iterator's next block row */
        unsigned next_entry;            /* Iterator's next block entry */
        unsigned min_dblock_row;        /* Minimum row for direct block size request */

        /* Compute min. row for direct block requested */
        min_dblock_row = H5HF_dtable_size_to_row(&hdr->man_dtable, min_dblock_size);

        /* Initialize block iterator, if necessary */
        if(!H5HF_man_iter_ready(&hdr->next_block)) {
            /* Start iterator with previous offset of iterator */
            if(H5HF_man_iter_start_offset(hdr, dxpl_id, &hdr->next_block, hdr->man_iter_off) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "unable to set block iterator location")
        } /* end if */

        /* Get information about current iterator location */
        if(H5HF_man_iter_curr(&hdr->next_block, &next_row, NULL, &next_entry, &iblock) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to retrieve current block iterator location")

        /* Check for skipping over blocks in the current block */
        if(min_dblock_row > next_row && next_row < iblock->nrows) {
            unsigned min_entry;         /* Min entry for direct block requested */
            unsigned skip_entries;      /* Number of entries to skip in the current block */

            /* Compute the number of entries to skip in the current block */
            min_entry = min_dblock_row * hdr->man_dtable.cparam.width;
            if(min_dblock_row >= iblock->nrows)
                skip_entries = (iblock->nrows * hdr->man_dtable.cparam.width) - next_entry;
            else
                skip_entries = min_entry - next_entry;

            /* Add skipped direct blocks to heap's free space */
            if(H5HF_hdr_skip_blocks(hdr, dxpl_id, iblock, next_entry, skip_entries) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTDEC, FAIL, "can't add skipped blocks to heap's free space")

            /* Get information about new iterator location */
            if(H5HF_man_iter_curr(&hdr->next_block, &next_row, NULL, &next_entry, &iblock) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to retrieve current block iterator location")
        } /* end if */

        do {
            /* Reset conditions for leaving loop */
            walked_up = walked_down = FALSE;

            /* Check for walking off end of indirect block */
            /* (walk up iterator) */
            while(next_row >= iblock->nrows) {
                /* Check for needing to expand root indirect block */
                if(iblock->parent == NULL) {
                    if(H5HF_man_iblock_root_double(hdr, dxpl_id, min_dblock_size) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTEXTEND, FAIL, "unable to double root indirect block")
                } /* end if */
                else {
                    /* Move iterator up one level */
                    if(H5HF_man_iter_up(&hdr->next_block) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTNEXT, FAIL, "unable to advance current block iterator location")

                    /* Increment location of next block at this level */
                    if(H5HF_man_iter_next(hdr, &hdr->next_block, 1) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTINC, FAIL, "can't advance fractal heap block location")
                } /* end else */

                /* Get information about new iterator location */
                if(H5HF_man_iter_curr(&hdr->next_block, &next_row, NULL, &next_entry, &iblock) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to retrieve current block iterator location")

                /* Indicate that we walked up */
                walked_up = TRUE;
            } /* end while */

            /* Check for walking into child indirect block */
            /* (walk down iterator) */
            if(next_row >= hdr->man_dtable.max_direct_rows) {
                unsigned child_nrows;   /* Number of rows in new indirect block */

                HDassert(!H5F_addr_defined(iblock->ents[next_entry].addr));

                /* Compute # of rows in next child indirect block to use */
                child_nrows = H5HF_dtable_size_to_rows(&hdr->man_dtable, hdr->man_dtable.row_block_size[next_row]);

                /* Check for skipping over indirect blocks */
                /* (that don't have direct blocks large enough to hold direct block size requested) */
                if(hdr->man_dtable.row_block_size[child_nrows - 1] < min_dblock_size) {
                    unsigned child_rows_needed;     /* Number of rows needed to hold direct block */
                    unsigned child_entry;           /* Entry of child indirect block */

                    /* Compute # of rows needed in child indirect block */
                    child_rows_needed = (H5VM_log2_of2((uint32_t)min_dblock_size) - H5VM_log2_of2((uint32_t)hdr->man_dtable.cparam.start_block_size)) + 2;
                    HDassert(child_rows_needed > child_nrows);
                    child_entry = (next_row + (child_rows_needed - child_nrows)) * hdr->man_dtable.cparam.width;
                    if(child_entry > (iblock->nrows * hdr->man_dtable.cparam.width))
                        child_entry = iblock->nrows * hdr->man_dtable.cparam.width;

                    /* Add skipped indirect blocks to heap's free space */
                    if(H5HF_hdr_skip_blocks(hdr, dxpl_id, iblock, next_entry, (child_entry - next_entry)) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTDEC, FAIL, "can't add skipped blocks to heap's free space")
                } /* end if */
                else {
                    H5HF_indirect_t *new_iblock;    /* Pointer to new indirect block */
                    hbool_t did_protect;            /* Whether we protected the indirect block or not */
                    haddr_t new_iblock_addr;        /* New indirect block's address */

                    /* Allocate new indirect block */
                    if(H5HF_man_iblock_create(hdr, dxpl_id, iblock, next_entry, child_nrows, child_nrows, &new_iblock_addr) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, FAIL, "can't allocate fractal heap indirect block")

                    /* Lock new indirect block */
                    if(NULL == (new_iblock = H5HF_man_iblock_protect(hdr, dxpl_id, new_iblock_addr, child_nrows, iblock, next_entry, FALSE, H5AC__NO_FLAGS_SET, &did_protect)))
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect fractal heap indirect block")

                    /* Move iterator down one level (pins indirect block) */
                    if(H5HF_man_iter_down(&hdr->next_block, new_iblock) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTNEXT, FAIL, "unable to advance current block iterator location")

                    /* Check for skipping over rows and add free section for skipped rows */
                    if(min_dblock_size > hdr->man_dtable.cparam.start_block_size) {
                        unsigned new_entry;        /* Entry of direct block which is large enough */

                        /* Compute entry for direct block size requested */
                        new_entry = hdr->man_dtable.cparam.width * min_dblock_row;

                        /* Add skipped blocks to heap's free space */
                        if(H5HF_hdr_skip_blocks(hdr, dxpl_id, new_iblock, 0, new_entry) < 0)
                            HGOTO_ERROR(H5E_HEAP, H5E_CANTDEC, FAIL, "can't add skipped blocks to heap's free space")
                    } /* end if */

                    /* Unprotect child indirect block */
                    if(H5HF_man_iblock_unprotect(new_iblock, dxpl_id, H5AC__NO_FLAGS_SET, did_protect) < 0)
                        HGOTO_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, FAIL, "unable to release fractal heap indirect block")
                } /* end else */

                /* Get information about new iterator location */
                if(H5HF_man_iter_curr(&hdr->next_block, &next_row, NULL, &next_entry, &iblock) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to retrieve current block iterator location")

                /* Indicate that we walked down */
                walked_down = TRUE;
            } /* end if */
        } while(walked_down || walked_up);
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_update_iter() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_inc_iter
 *
 * Purpose:	Advance "next block" iterator
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May 23 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_inc_iter(H5HF_hdr_t *hdr, hsize_t adv_size, unsigned nentries)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(nentries);

    /* Advance the iterator for the current location within the indirect block */
    if(hdr->next_block.curr)
        if(H5HF_man_iter_next(hdr, &hdr->next_block, nentries) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTNEXT, FAIL, "unable to advance current block iterator location")

    /* Increment the offset of the iterator in the heap */
    hdr->man_iter_off += adv_size;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_inc_iter() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_reverse_iter
 *
 * Purpose:	Walk "next block" iterator backwards until the correct
 *              location to allocate next block from is found
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May 31 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_reverse_iter(H5HF_hdr_t *hdr, hid_t dxpl_id, haddr_t dblock_addr)
{
    H5HF_indirect_t *iblock;            /* Indirect block where iterator is located */
    unsigned curr_entry;                /* Current entry for iterator */
    hbool_t walked_down;                /* Loop flag */
    hbool_t walked_up;                  /* Loop flag */
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Initialize block iterator, if necessary */
    if(!H5HF_man_iter_ready(&hdr->next_block))
        /* Start iterator with previous offset of iterator */
        if(H5HF_man_iter_start_offset(hdr, dxpl_id, &hdr->next_block, hdr->man_iter_off) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "unable to set block iterator location")

    /* Walk backwards through heap, looking for direct block to place iterator after */

    /* Get information about current iterator location */
    if(H5HF_man_iter_curr(&hdr->next_block, NULL, NULL, &curr_entry, &iblock) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to retrieve current block iterator information")

    /* Move current iterator position backwards once */
    curr_entry--;

    /* Search backwards in the heap address space for direct block to latch onto */
    do {
        int tmp_entry;     /* Temp. entry for iterator (use signed value to detect errors) */

        /* Reset loop flags */
        walked_down = FALSE;
        walked_up = FALSE;

        /* Walk backwards through entries, until we find one that has a child */
        /* (Skip direct block that will be deleted, if we find it) */
        tmp_entry = (int)curr_entry;
        while(tmp_entry >= 0 &&
                (H5F_addr_eq(iblock->ents[tmp_entry].addr, dblock_addr) ||
                    !H5F_addr_defined(iblock->ents[tmp_entry].addr)))
            tmp_entry--;
        /* Check for no earlier blocks in this indirect block */
        if(tmp_entry < 0) {
            /* Check for parent of current indirect block */
            if(iblock->parent) {
                /* Move iterator to parent of current block */
                if(H5HF_man_iter_up(&hdr->next_block) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTNEXT, FAIL, "unable to move current block iterator location up")

                /* Get information about current iterator location */
                if(H5HF_man_iter_curr(&hdr->next_block, NULL, NULL, &curr_entry, &iblock) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to retrieve current block iterator information")

                /* Move current iterator position backwards once */
                curr_entry--;

                /* Note that we walked up */
                walked_up = TRUE;
            } /* end if */
            else {
                /* Reset iterator offset */
                hdr->man_iter_off = 0;

                /* Reset 'next block' iterator */
                if(H5HF_man_iter_reset(&hdr->next_block) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTRELEASE, FAIL, "can't reset block iterator")
            } /* end else */
        } /* end if */
        else {
            unsigned row;           /* Row for entry */

            curr_entry = (unsigned)tmp_entry;

            /* Check if entry is for a direct block */
            row = curr_entry / hdr->man_dtable.cparam.width;
            if(row < hdr->man_dtable.max_direct_rows) {
                /* Increment entry to empty location */
                curr_entry++;

                /* Set the current location of the iterator to next entry after the existing direct block */
                if(H5HF_man_iter_set_entry(hdr, &hdr->next_block, curr_entry) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTSET, FAIL, "unable to set current block iterator location")

                /* Update iterator offset */
                hdr->man_iter_off = iblock->block_off;
                hdr->man_iter_off += hdr->man_dtable.row_block_off[curr_entry / hdr->man_dtable.cparam.width];
                hdr->man_iter_off += hdr->man_dtable.row_block_size[curr_entry / hdr->man_dtable.cparam.width] * (curr_entry % hdr->man_dtable.cparam.width);
            } /* end if */
            else {
                H5HF_indirect_t *child_iblock;  /* Pointer to child indirect block */
                hbool_t did_protect;            /* Whether we protected the indirect block or not */
                unsigned child_nrows;           /* # of rows in child block */

                /* Compute # of rows in next child indirect block to use */
                child_nrows = H5HF_dtable_size_to_rows(&hdr->man_dtable, hdr->man_dtable.row_block_size[row]);

                /* Lock child indirect block */
                if(NULL == (child_iblock = H5HF_man_iblock_protect(hdr, dxpl_id, iblock->ents[curr_entry].addr, child_nrows, iblock, curr_entry, FALSE, H5AC__NO_FLAGS_SET, &did_protect)))
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect fractal heap indirect block")

                /* Set the current location of the iterator */
                if(H5HF_man_iter_set_entry(hdr, &hdr->next_block, curr_entry) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTSET, FAIL, "unable to set current block iterator location")

                /* Walk down into child indirect block (pins child block) */
                if(H5HF_man_iter_down(&hdr->next_block, child_iblock) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTNEXT, FAIL, "unable to advance current block iterator location")

                /* Update iterator location */
                iblock = child_iblock;
                curr_entry = (child_iblock->nrows * hdr->man_dtable.cparam.width) - 1;

                /* Unprotect child indirect block */
                if(H5HF_man_iblock_unprotect(child_iblock, dxpl_id, H5AC__NO_FLAGS_SET, did_protect) < 0)
                    HGOTO_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, FAIL, "unable to release fractal heap indirect block")

                /* Note that we walked down */
                walked_down = TRUE;
            } /* end else */
        } /* end else */
    } while(walked_down || walked_up);

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_reverse_iter() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_empty
 *
 * Purpose:	Reset heap header to 'empty heap' state
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		May 17 2006
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_empty(H5HF_hdr_t *hdr)
{
    herr_t ret_value = SUCCEED;         /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /* Sanity check */
    HDassert(hdr);

    /* Reset block iterator, if necessary */
    if(H5HF_man_iter_ready(&hdr->next_block)) {
        if(H5HF_man_iter_reset(&hdr->next_block) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTRELEASE, FAIL, "can't reset block iterator")
    } /* end if */

    /* Shrink managed heap size */
    hdr->man_size = 0;
    hdr->man_alloc_size = 0;

    /* Reset the 'next block' iterator location */
    hdr->man_iter_off = 0;

    /* Reset the free space in direct blocks */
    hdr->total_man_free = 0;

    /* Mark heap header as modified */
    if(H5HF_hdr_dirty(hdr) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark header as dirty")

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_empty() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_free
 *
 * Purpose:	Free shared fractal heap header
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@hdfgroup.org
 *		Oct 27 2009
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_free(H5HF_hdr_t *hdr)
{
    herr_t      ret_value = SUCCEED;    /* Return value */

    FUNC_ENTER_NOAPI_NOINIT

    /*
     * Check arguments.
     */
    HDassert(hdr);

    /* Free the block size lookup table for the doubling table */
    if(H5HF_dtable_dest(&hdr->man_dtable) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap doubling table")

    /* Release any I/O pipeline filter information */
    if(hdr->pline.nused)
        if(H5O_msg_reset(H5O_PLINE_ID, &(hdr->pline)) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to reset I/O pipeline message")

    /* Free the shared info itself */
    hdr = H5FL_FREE(H5HF_hdr_t, hdr);

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_free() */


/*-------------------------------------------------------------------------
 * Function:	H5HF_hdr_delete
 *
 * Purpose:	Delete a fractal heap, starting with the header
 *
 * Return:	SUCCEED/FAIL
 *
 * Programmer:	Quincey Koziol
 *		koziol@hdfgroup.org
 *		Jan  5 2007
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5HF_hdr_delete(H5HF_hdr_t *hdr, hid_t dxpl_id)
{
    unsigned cache_flags = H5AC__NO_FLAGS_SET;  /* Flags for unprotecting heap header */
    herr_t ret_value = SUCCEED;                 /* Return value */

    FUNC_ENTER_NOAPI(FAIL)

    /*
     * Check arguments.
     */
    HDassert(hdr);
    HDassert(!hdr->file_rc);

#ifndef NDEBUG
{
    unsigned hdr_status = 0;         /* Heap header's status in the metadata cache */

    /* Check the heap header's status in the metadata cache */
    if(H5AC_get_entry_status(hdr->f, hdr->heap_addr, &hdr_status) < 0)
        HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "unable to check metadata cache status for heap header")

    /* Sanity checks on heap header */
    HDassert(hdr_status & H5AC_ES__IN_CACHE);
    HDassert(hdr_status & H5AC_ES__IS_PROTECTED);
} /* end block */
#endif /* NDEBUG */

    /* Check for free space manager for heap */
    /* (must occur before attempting to delete the heap, so indirect blocks
     *  will get unpinned)
     */
    if(H5F_addr_defined(hdr->fs_addr)) {
        /* Delete free space manager for heap */
        if(H5HF_space_delete(hdr, dxpl_id) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to release fractal heap free space manager")
    } /* end if */

    /* Check for root direct/indirect block */
    if(H5F_addr_defined(hdr->man_dtable.table_addr)) {
        if(hdr->man_dtable.curr_root_rows == 0) {
            hsize_t dblock_size;        /* Size of direct block */

            /* Check for I/O filters on this heap */
            if(hdr->filter_len > 0) {
                dblock_size = (hsize_t)hdr->pline_root_direct_size;

                /* Reset the header's pipeline information */
                hdr->pline_root_direct_size = 0;
                hdr->pline_root_direct_filter_mask = 0;
            } /* end else */
            else
                dblock_size = (hsize_t)hdr->man_dtable.cparam.start_block_size;

            /* Delete root direct block */
            if(H5HF_man_dblock_delete(hdr->f, dxpl_id, hdr->man_dtable.table_addr, dblock_size) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to release fractal heap root direct block")
        } /* end if */
        else {
            /* Delete root indirect block */
            if(H5HF_man_iblock_delete(hdr, dxpl_id, hdr->man_dtable.table_addr, hdr->man_dtable.curr_root_rows, NULL, 0) < 0)
                HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to release fractal heap root indirect block")
        } /* end else */
    } /* end if */

    /* Check for 'huge' objects in heap */
    if(H5F_addr_defined(hdr->huge_bt2_addr)) {
        /* Delete huge objects in heap and their tracker */
        if(H5HF_huge_delete(hdr, dxpl_id) < 0)
            HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to release fractal heap 'huge' objects and tracker")
    } /* end if */

    /* Indicate that the heap header should be deleted & file space freed */
    cache_flags |= H5AC__DIRTIED_FLAG | H5AC__DELETED_FLAG | H5AC__FREE_FILE_SPACE_FLAG;

done:
    /* Unprotect the header with appropriate flags */
    if(H5AC_unprotect(hdr->f, dxpl_id, H5AC_FHEAP_HDR, hdr->heap_addr, hdr, cache_flags) < 0)
        HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, FAIL, "unable to release fractal heap header")

    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5HF_hdr_delete() */