path: root/src/H5BT.c

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

/*-------------------------------------------------------------------------
 *
 * Created:		H5BT.c
 *			Mar  9 2005
 *			Quincey Koziol <koziol@ncsa.uiuc.edu>
 *
 * Purpose:		Tracks blocks of bytes in a file
 *
 *-------------------------------------------------------------------------
 */

#define H5BT_PACKAGE		/*suppress error about including H5BTpkg  */

/* Private headers */
#include "H5private.h"		/* Generic Functions			*/
#include "H5BTpkg.h"		/* Block tracker			*/
#include "H5Eprivate.h"		/* Error handling		  	*/
#include "H5MFprivate.h"	/* File memory management		*/

/* Local macros */

/* v2 B-tree settings */
#define H5BT_BT2_NODE_SIZE      512
#define H5BT_BT2_RREC_SIZE(f)   (H5F_SIZEOF_ADDR(f) + H5F_SIZEOF_SIZE(f))    /* Offset & length of block tracked */
#define H5BT_BT2_SPLIT_PERC     100
#define H5BT_BT2_MERGE_PERC     40

/* Local typedefs */

/* Struct for locating blocks */
typedef struct {
    hsize_t search_size;        /* Size of block to search for */
    H5BT_blk_info_t found;      /* Information for block found */
} H5BT_locate_t;

/* Local prototypes */

/* Package variables */

/* Declare a free list to manage the H5BT_t struct */
H5FL_DEFINE(H5BT_t);

/* Static variables */


/*-------------------------------------------------------------------------
 * Function:	H5BT_create
 *
 * Purpose:	Creates a new empty block tracker in the file.
 *
 * Return:	Non-negative on success (with address of new block tracker
 *              filled in), negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 10 2005
 *
 * Modifications:
 *
 *
 *              John Mainzer 6/8/05
 *              Removed code setting the is_dirty field of the cache info.
 *              This is no longer pemitted, as the cache code is now
 *              manageing this field.  Since this function uses a call to
 *              H5AC_set() (which marks the entry dirty automaticly), no
 *              other change is required.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_create(H5F_t *f, hid_t dxpl_id, haddr_t *addr_p)
{
    H5BT_t *bt = NULL;                 /* The new B-tree header information */
    herr_t ret_value=SUCCEED;

    FUNC_ENTER_NOAPI(H5BT_create, FAIL)

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

    /*
     * Allocate file and memory data structures.
     */
    if (NULL==(bt = H5FL_CALLOC(H5BT_t)))
	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for block tracker info")

    /* Assign internal information */
    bt->max_block_size = 0;             /* Indicate that the value is invalid */
    bt->min_block_size = HSIZET_MAX;    /* Indicate that the value is invalid */

    /* Allocate space for the header on disk */
    if (HADDR_UNDEF==(*addr_p=H5MF_alloc(f, H5FD_MEM_BLKTRK, dxpl_id, (hsize_t)H5BT_SIZE(f))))
	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for block tracker info")

    /* Create a B-tree for storing the block info records */
    if (H5B2_create(f, dxpl_id, H5B2_BLKTRK, H5BT_BT2_NODE_SIZE, H5BT_BT2_RREC_SIZE(f), H5BT_BT2_SPLIT_PERC, H5BT_BT2_MERGE_PERC, &bt->bt2_addr/*out*/)<0)
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTINIT, FAIL, "can't create B-tree for storing block info")

    /* Cache the new block tracker node */
    if (H5AC_set(f, dxpl_id, H5AC_BLTR, *addr_p, bt, H5AC__NO_FLAGS_SET) < 0)
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTINIT, FAIL, "can't add block tracker info to cache")

done:
    if (ret_value<0) {
	if (bt)
            (void)H5BT_cache_dest(f,bt);
    } /* end if */
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_create() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_insert_neighbor_cb
 *
 * Purpose:	v2 B-tree neighbor callback for H5BT_insert()
 *
 * Return:	Success:	0
 *
 *		Failure:	1
 *
 * Programmer:	Quincey Koziol
 *              Thursday, March 10, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static int
H5BT_insert_neighbor_cb(const void *_record, void *_op_data)
{
    const H5BT_blk_info_t *record = (const H5BT_blk_info_t *)_record;
    H5BT_blk_info_t *search = (H5BT_blk_info_t *)_op_data;

    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5BT_insert_neighbor_cb)

    *search = *record;

    FUNC_LEAVE_NOAPI(0)
} /* end H5BT_insert_neighbor_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_insert_modify_cb
 *
 * Purpose:	v2 B-tree modify callback for H5BT_insert()
 *
 * Return:	Success:	0
 *
 *		Failure:	1
 *
 * Programmer:	Quincey Koziol
 *              Friday, March 11, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static int
H5BT_insert_modify_cb(void *_record, void *_op_data, hbool_t *changed)
{
    H5BT_blk_info_t *record = (H5BT_blk_info_t *)_record;
    H5BT_blk_info_t *modify = (H5BT_blk_info_t *)_op_data;

    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5BT_insert_modify_cb)

    *record = *modify;
    *changed = TRUE;

    FUNC_LEAVE_NOAPI(0)
} /* end H5BT_insert_modify_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_insert
 *
 * Purpose:	Insert new block (offset/length) into a block tracker.
 *              Duplicate and overlapping blocks are rejected.
 *
 * Return:	Non-negative on success, negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 10 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/8/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_insert(H5F_t *f, hid_t dxpl_id, haddr_t addr, haddr_t offset, hsize_t length)
{
    unsigned bt_flags = H5AC__NO_FLAGS_SET;
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    H5BT_blk_info_t lower, upper;       /* Info for blocks less than & greater than new block */
    hbool_t lower_valid = FALSE, upper_valid = FALSE;   /* Lower & upper blocks valid? */
    H5BT_blk_info_t new_block;          /* Info for new block */
    hsize_t nblks;                      /* Number of blocks tracked */
    unsigned merged = 0;                /* How many blocks were merged with */
    herr_t ret_value=SUCCEED;

    FUNC_ENTER_NOAPI(H5BT_insert, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Check for block at this address already */
    if (H5B2_find(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &offset, NULL, NULL) >= 0)
	HGOTO_ERROR(H5E_BLKTRK, H5E_EXISTS, FAIL, "block at address already exists")
    /* Clear any errors from H5B2_find() */
    H5E_clear_stack(NULL);

    /* Find next block lower than the new block */
    if ( H5B2_neighbor(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, H5B2_COMPARE_LESS, &offset, H5BT_insert_neighbor_cb, &lower) >= 0) {
        if ( H5F_addr_overlap(lower.addr, lower.len, offset, length) )
            HGOTO_ERROR(H5E_BLKTRK, H5E_OVERLAPS, FAIL, "new block overlaps existing block")

        /* Set flag to indicate lower bound found */
        lower_valid = TRUE;
    } /* end if */
    /* Clear any errors from H5B2_neighbor() */
    H5E_clear_stack(NULL);

    /* Find next block higher than the new block */
    if ( H5B2_neighbor(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, H5B2_COMPARE_GREATER, &offset, H5BT_insert_neighbor_cb, &upper) >= 0) {
        if ( H5F_addr_overlap(upper.addr, upper.len, offset, length) )
            HGOTO_ERROR(H5E_BLKTRK, H5E_OVERLAPS, FAIL, "new block overlaps existing block")

        /* Set flag to indicate upper bound found */
        upper_valid = TRUE;
    } /* end if */
    /* Clear any errors from H5B2_neighbor() */
    H5E_clear_stack(NULL);

    /* Check for merged blocks */
    if(lower_valid || upper_valid) {
        H5BT_blk_info_t *old_block=NULL;    /* Pointer to info for block merged with */

        /* Check if the new block should merge with both the lower & upper blocks */
        if((lower_valid && (lower.addr+lower.len) == offset)
                && (upper_valid && (offset+length) == upper.addr)) {
            /* Delete upper block */
            if(H5B2_remove(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &upper)<0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTDELETE, FAIL, "can't remove block")

            /* Update existing lower block */
            new_block.addr = lower.addr;
            new_block.len = lower.len + length + upper.len;
            if(H5B2_modify(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &lower, H5BT_insert_modify_cb, &new_block) < 0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTMODIFY, FAIL, "can't change block size")

            /* Merged with 2 blocks */
            merged = 2;
        } /* end if */
        /* Check if the new block should merge with just the lower block */
        else if(lower_valid && (lower.addr+lower.len) == offset) {
            /* Update existing lower block */
            new_block.addr = lower.addr;
            new_block.len = lower.len + length;
            if(H5B2_modify(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &lower, H5BT_insert_modify_cb, &new_block) < 0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTMODIFY, FAIL, "can't change block size")

            /* Indicate which block we merged with */
            old_block = &lower;

            /* Merged with 1 block */
            merged = 1;
        } /* end else */
        /* Check if the new block should merge with just the upper block */
        else if(upper_valid && (offset+length) == upper.addr) {
            /* Update existing upper block */
            new_block.addr = offset;
            new_block.len = length + upper.len;
            if(H5B2_modify(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &upper, H5BT_insert_modify_cb, &new_block) < 0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTMODIFY, FAIL, "can't change block size")

            /* Indicate which block we merged with */
            old_block = &upper;

            /* Merged with 1 block */
            merged = 1;
        } /* end else */

        /* Check for adjusting the block tracking metadata */
        if(merged == 1) {
            /* Check for adjusting the max. block size tracked */
            if(new_block.len > bt->max_block_size) {
                bt->max_block_size = new_block.len;
                bt->max_block_cnt = 1;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end if */
            else if(new_block.len == bt->max_block_size) {
                bt->max_block_cnt++;
                bt_flags |= H5AC__DIRTIED_FLAG;
            }

            /* Check for adjusting the min. block size tracked */
            if(old_block->len < bt->min_block_size) {
                /* This should only happen if we don't have full knowledge of all the blocks' sizes */
                HDassert((bt->status & H5BT_STATUS_MIN_VALID) == 0);

                if(new_block.len < bt->min_block_size) {
                    bt->min_block_size = new_block.len;
                    bt->min_block_cnt = 1;
                    bt_flags |= H5AC__DIRTIED_FLAG;
                } /* end if */
            } /* end if */
            else if(old_block->len == bt->min_block_size) {
                /* If this was the minimum block, indicate that the min. size
                 * is no longer guaranteed valid over the whole set of blocks
                 * tracked and use the new block size as the minimum value */
                if(bt->min_block_cnt == 1) {
                    bt->min_block_size = new_block.len;
                    bt->status &= ~H5BT_STATUS_MIN_VALID;
                    bt_flags |= H5AC__DIRTIED_FLAG;
                } /* end if */
                else {
                    /* Decrement the ref. count for the min. block size */
                    bt->min_block_cnt--;
                    bt_flags |= H5AC__DIRTIED_FLAG;
                } /* end else */
            } /* end if */
        } /* end if */
        else if(merged == 2) {
            /* Check for adjusting the max. block size tracked */
            if(new_block.len > bt->max_block_size) {
                bt->max_block_size = new_block.len;
                bt->max_block_cnt = 1;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end if */
            else if(new_block.len == bt->max_block_size) {
                bt->max_block_cnt++;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end else */

            /* Check for adjusting the min. block size tracked */
            if(upper.len < bt->min_block_size || lower.len < bt->min_block_size) {
                /* This should only happen if we don't have full knowledge of all the blocks' sizes */
                HDassert((bt->status & H5BT_STATUS_MIN_VALID) == 0);

                if(new_block.len < bt->min_block_size) {
                    bt->min_block_size = new_block.len;
                    bt->min_block_cnt = 1;
                    bt_flags |= H5AC__DIRTIED_FLAG;
                } /* end if */
            } /* end if */
            else if(upper.len == bt->min_block_size || lower.len == bt->min_block_size) {
                /* If this was the minimum block, indicate that the min. size
                 * is no longer guaranteed valid over the whole set of blocks
                 * tracked and use the new block size as the minimum value */
                if(bt->min_block_cnt == 1) {
                    bt->min_block_size = new_block.len;
                    bt->status &= ~H5BT_STATUS_MIN_VALID;
                    bt_flags |= H5AC__DIRTIED_FLAG;
                } /* end if */
                else {
                    /* Decrement the ref. count for the min. block size */
                    bt->min_block_cnt--;
                    bt_flags |= H5AC__DIRTIED_FLAG;
                } /* end else */
            } /* end if */
        } /* end if */
    } /* end if */

    /* Insert new block into B-tree, if it wasn't marged already*/
    if(!merged) {
        new_block.addr = offset;
        new_block.len = length;
        if(H5B2_insert(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &new_block) < 0)
            HGOTO_ERROR(H5E_BLKTRK, H5E_CANTINSERT, FAIL, "unable to insert block")

        /* Update block tracker metadata */

        /* Determine the number of blocks being tracked */
        if(H5B2_get_nrec(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &nblks) < 0)
            HGOTO_ERROR(H5E_BLKTRK, H5E_CANTINSERT, FAIL, "unable to determine # of blocks")

        /* This is the only block tracked so far */
        if(nblks == 1) {
            bt->max_block_size = length;
            bt->max_block_cnt = 1;
            bt->status |= H5BT_STATUS_MAX_VALID;
            bt->min_block_size = length;
            bt->min_block_cnt = 1;
            bt->status |= H5BT_STATUS_MIN_VALID;
            bt_flags |= H5AC__DIRTIED_FLAG;
        } /* end if */
        else {
            /* Update maximum block size */
            if (length > bt->max_block_size) {
                bt->max_block_size = length;
                bt->max_block_cnt = 1;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end if */
            else if (length == bt->max_block_size) {
                bt->max_block_cnt++;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end if */

            /* Update minimum block size */
            if (length < bt->min_block_size) {
                bt->min_block_size = length;
                bt->min_block_cnt = 1;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end if */
            else if (length == bt->min_block_size) {
                bt->min_block_cnt++;
                bt_flags |= H5AC__DIRTIED_FLAG;
            } /* end if */
        } /* end if */
    } /* end if */

    /* Increment total number of bytes tracked in all blocks */
    bt->tot_block_size += length;

done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, bt_flags) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_insert() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_get_total_size
 *
 * Purpose:	Query the total amount of bytes tracked
 *
 * Return:	Non-negative on success, negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 10 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/17/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_get_total_size(H5F_t *f, hid_t dxpl_id, haddr_t addr, hsize_t *tot_size)
{
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    herr_t ret_value=SUCCEED;

    FUNC_ENTER_NOAPI(H5BT_get_total_size, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_READ)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Save total number of bytes tracked in all blocks */
    *tot_size = bt->tot_block_size;

done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, H5AC__NO_FLAGS_SET) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_get_total_size() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_remove_find_cb
 *
 * Purpose:	v2 B-tree find callback
 *
 * Return:	Success:	0
 *
 *		Failure:	1
 *
 * Programmer:	Quincey Koziol
 *              Friday, March 11, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static int
H5BT_remove_find_cb(const void *_record, void *_op_data)
{
    const H5BT_blk_info_t *record = (const H5BT_blk_info_t *)_record;
    H5BT_blk_info_t *search = (H5BT_blk_info_t *)_op_data;

    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5BT_remove_find_cb)

    /* Copy the data out */
    *search = *record;

    FUNC_LEAVE_NOAPI(0);
} /* end H5BT_remove_find_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_remove
 *
 * Purpose:	Remove a block (offset/length) from a block tracker.
 *
 * Return:	Non-negative on success, negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 11 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/8/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_remove(H5F_t *f, hid_t dxpl_id, haddr_t addr, haddr_t offset, hsize_t length)
{
    unsigned bt_flags = H5AC__NO_FLAGS_SET;
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    H5BT_blk_info_t found;              /* Block info found */
    hsize_t nblks;                      /* Number of blocks tracked */
    herr_t ret_value=SUCCEED;

    FUNC_ENTER_NOAPI(H5BT_remove, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Check for block at this address already */
    if (H5B2_find(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &offset, H5BT_remove_find_cb, &found) < 0) {
        /* Clear any errors from H5B2_find() */
        H5E_clear_stack(NULL);

        /* Find next block lower */
HDfprintf(stderr,"%s: Need to search for lower & upper block!\n",FUNC);
HGOTO_ERROR(H5E_BLKTRK, H5E_UNSUPPORTED, FAIL, "Couldn't find block to remove")
    } /* end if */
    else {
        /* Found block at address */

        /* Check for exact fit */
        if(found.len == length) {
            /* Delete record from B-tree */
            if(H5B2_remove(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &found)<0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTDELETE, FAIL, "can't remove block")

            /* Determine the number of blocks being tracked */
            if(H5B2_get_nrec(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &nblks) < 0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTINSERT, FAIL, "unable to determine # of blocks")

            /* Check for no blocks left */
            if(nblks == 0) {
                bt->max_block_size = 0;             /* Indicate that the value is invalid */
                bt->max_block_cnt = 0;
                bt->min_block_size = HSIZET_MAX;    /* Indicate that the value is invalid */
                bt->min_block_cnt = 0;
                bt->status = 0;
            } /* end if */
            else {
                /* Update max. block metadata */
                if(found.len == bt->max_block_size) {
                    /* Decrement maximum block count */
                    bt->max_block_cnt--;

                    /* Check if we don't know the maximum size any longer */
                    if(bt->max_block_cnt==0) {
                        if(bt->min_block_size < HSIZET_MAX) {
                            bt->max_block_size = bt->min_block_size;
                            bt->max_block_cnt = bt->min_block_cnt;
                        } /* end if */
                        else
                            bt->max_block_size = 0;
                        bt->status &= ~H5BT_STATUS_MAX_VALID;
                    } /* end if */
                } /* end if */

                /* Update min. block metadata */
                if(found.len == bt->min_block_size) {
                    /* Decrement minimum block count */
                    bt->min_block_cnt--;

                    /* Check if we don't know the minimum size any longer */
                    if(bt->min_block_cnt==0) {
                        if(bt->max_block_size > 0) {
                            bt->min_block_size = bt->max_block_size;
                            bt->min_block_cnt = bt->max_block_cnt;
                        } /* end if */
                        else
                            bt->min_block_size = HSIZET_MAX;
                        bt->status &= ~H5BT_STATUS_MIN_VALID;
                    } /* end if */
                } /* end if */
            } /* end else */

            /* Decrement total amount of blocks tracked */
            bt->tot_block_size -= length;

            /* Flag block tracker info as changed */
            bt_flags |= H5AC__DIRTIED_FLAG;
        } /* end if */
        else if(found.len > length) {
            H5BT_blk_info_t new_block;              /* Updated block info */

            /* Update existing lower block */
            new_block.addr = found.addr + length;
            new_block.len = found.len - length;
            if(H5B2_modify(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, &found, H5BT_insert_modify_cb, &new_block) < 0)
                HGOTO_ERROR(H5E_BLKTRK, H5E_CANTMODIFY, FAIL, "can't change block size")

            /* Update max. block metadata */
            if(found.len == bt->max_block_size) {
                /* Decrement maximum block count */
                bt->max_block_cnt--;

                /* Check if we don't know the maximum size any longer */
                if(bt->max_block_cnt==0) {
                    bt->max_block_size = new_block.len;
                    bt->max_block_cnt = 1;
                    bt->status &= ~H5BT_STATUS_MAX_VALID;
                } /* end if */
            } /* end if */
            else if(new_block.len > bt->max_block_size) {
                /* Should only happen if we have partial knowledge */
                HDassert((bt->status & H5BT_STATUS_MAX_VALID) == 0);

                /* Track the newly discovered max. block size */
                bt->max_block_size = new_block.len;
                bt->max_block_cnt = 1;
            } /* end if */
            else if(new_block.len == bt->max_block_size) {
                /* Should only happen if we have partial knowledge */
                HDassert((bt->status & H5BT_STATUS_MAX_VALID) == 0);

                bt->max_block_cnt++;
            } /* end if */

            /* Update min. block metadata */
            if(new_block.len < bt->min_block_size) {
                bt->min_block_size = new_block.len;
                bt->min_block_cnt = 1;
            } /* end if */
            else if(new_block.len == bt->min_block_size)
                bt->min_block_cnt++;

            /* Decrement total amount of blocks tracked */
            bt->tot_block_size -= length;

            /* Flag block tracker info as changed */
            bt_flags |= H5AC__DIRTIED_FLAG;
        } /* end if */
        else {
            /* Check for blocks at higher address, if necessary */
HDfprintf(stderr,"%s: found={%a/%Hu}\n",FUNC,found.addr,found.len);
HGOTO_ERROR(H5E_BLKTRK, H5E_UNSUPPORTED, FAIL, "Couldn't find block to remove")
        } /* end else */
    } /* end else */

done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, bt_flags) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_remove() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_locate_cb
 *
 * Purpose:	Block tracker "locate" callback
 *
 * Return:	Success:	0
 *
 *		Failure:	1
 *
 * Programmer:	Quincey Koziol
 *              Friday, March 25, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static int
H5BT_locate_cb(const void *_record, void *_op_data)
{
    const H5BT_blk_info_t *record = (const H5BT_blk_info_t *)_record;
    H5BT_locate_t *search = (H5BT_locate_t *)_op_data;
    int ret_value;              /* Return value */

    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5BT_locate_cb)

    /* Check if we've found a block that's big enough */
    if (record->len >= search->search_size) {
        search->found = *record;
        ret_value = H5B2_ITER_STOP;
    } /* end if */
    else
        ret_value = H5B2_ITER_CONT;

    FUNC_LEAVE_NOAPI(ret_value);
} /* end H5BT_locate_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_locate
 *
 * Purpose:	Locate first block that is at least a certain size
 *
 * Return:	Non-negative on success, negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 24 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/8/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
htri_t
H5BT_locate(H5F_t *f, hid_t dxpl_id, haddr_t addr, hsize_t size, haddr_t *locate_addr, hsize_t *locate_size)
{
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    H5BT_locate_t found;                /* Block info found */
    htri_t ret_value=TRUE;

    FUNC_ENTER_NOAPI(H5BT_locate, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_READ)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Iterate through blocks, looking for first one that is large enough */
    found.search_size = size;
    found.found.addr = HADDR_UNDEF;
    if (H5B2_iterate(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, H5BT_locate_cb, &found) < 0)
	HGOTO_ERROR(H5E_BLKTRK, H5E_NOTFOUND, FAIL, "unable to iterate over blocks")

    /* Update user's information, if block was found */
    if(H5F_addr_defined(found.found.addr)) {
        if(locate_addr)
            *locate_addr = found.found.addr;
        if(locate_size)
            *locate_size = found.found.len;
    } /* end if */
    else
        ret_value = FALSE;

done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, H5AC__NO_FLAGS_SET) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_locate() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_iterate
 *
 * Purpose:	Iterate over blocks in tracker, making callback for each
 *
 *              If the callback returns non-zero, the iteration breaks out
 *              without finishing all the records.
 *
 * Return:	Value from callback: non-negative on success, negative on error
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 25 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/8/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_iterate(H5F_t *f, hid_t dxpl_id, haddr_t addr, H5BT_operator_t op, void *op_data)
{
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    herr_t ret_value;

    FUNC_ENTER_NOAPI(H5BT_iterate, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_READ)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Iterate through blocks, passing along op & op_data */
    if ((ret_value = H5B2_iterate(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, (H5B2_operator_t)op, op_data)) < 0)
	HGOTO_ERROR(H5E_BLKTRK, H5E_NOTFOUND, FAIL, "unable to iterate over blocks")

done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, H5AC__NO_FLAGS_SET) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_iterate() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_neighbor_cb
 *
 * Purpose:	Block tracker "neighbor" callback
 *
 * Return:	Success:	0
 *
 *		Failure:	1
 *
 * Programmer:	Quincey Koziol
 *              Monday, March 28, 2005
 *
 * Modifications:
 *
 *-------------------------------------------------------------------------
 */
static int
H5BT_neighbor_cb(const void *_record, void *_op_data)
{
    const H5BT_blk_info_t *record = (const H5BT_blk_info_t *)_record;
    H5BT_blk_info_t *search = (H5BT_blk_info_t *)_op_data;

    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5BT_neighbor_cb)

    /* Save block information for later */
    *search = *record;

    FUNC_LEAVE_NOAPI(SUCCEED);
} /* end H5BT_neighbor_cb() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_neighbor
 *
 * Purpose:	Locate block that is related to a given address
 *
 * Return:	Non-negative on success, negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 28 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/8/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_neighbor(H5F_t *f, hid_t dxpl_id, haddr_t addr, H5BT_compare_t range,
    haddr_t range_addr, H5BT_blk_info_t *found_block)
{
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    H5BT_blk_info_t find;               /* Information for locating block */
    H5BT_blk_info_t found;              /* Block info found */
    herr_t ret_value = SUCCEED;

    FUNC_ENTER_NOAPI(H5BT_neighbor, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_READ)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Iterate through blocks, looking for first one that is large enough */
    find.addr = range_addr;
    find.len = 0;
    found.addr = HADDR_UNDEF;
    if (H5B2_neighbor(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr, (H5B2_compare_t)range,
            &find, H5BT_neighbor_cb, &found) < 0)
	HGOTO_ERROR(H5E_BLKTRK, H5E_NOTFOUND, FAIL, "unable to find neighbor for block")

    /* Update user's information, if block was found */
    if(H5F_addr_defined(found.addr))
        *found_block = found;

done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, H5AC__NO_FLAGS_SET) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_neighbor() */


/*-------------------------------------------------------------------------
 * Function:	H5BT_delete
 *
 * Purpose:	Delete a block tracker from a file
 *
 * Return:	Non-negative on success, negative on failure
 *
 * Programmer:	Quincey Koziol
 *		koziol@ncsa.uiuc.edu
 *		Mar 14 2005
 *
 * Modifications:
 *
 *              John Mainzer, 6/8/05
 *              Modified the function to use the new dirtied parameter of
 *              of H5AC_unprotect() instead of modifying the is_dirty
 *              field of the cache info.
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5BT_delete(H5F_t *f, hid_t dxpl_id, haddr_t addr)
{
    H5BT_t *bt = NULL;                  /* The new B-tree header information */
    herr_t ret_value=SUCCEED;

    FUNC_ENTER_NOAPI(H5BT_delete, FAIL)

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

    /* Look up the block tracker header */
    if (NULL == (bt = H5AC_protect(f, dxpl_id, H5AC_BLTR, addr, NULL, NULL, H5AC_WRITE)))
	HGOTO_ERROR(H5E_BLKTRK, H5E_CANTPROTECT, FAIL, "unable to load block tracker info")

    /* Delete B-tree */
    if (H5B2_delete(f, dxpl_id, H5B2_BLKTRK, bt->bt2_addr) < 0)
        HGOTO_ERROR(H5E_BLKTRK, H5E_CANTDELETE, FAIL, "Couldn't delete underlying B-tree")

    /* Release space for block tracker info on disk */
    if (H5MF_xfree(f, H5FD_MEM_BLKTRK, dxpl_id, addr, (hsize_t)H5BT_SIZE(f))<0)
        HGOTO_ERROR(H5E_BTREE, H5E_CANTFREE, FAIL, "unable to free block tracker info")
    
done:
    /* Release the block tracker info */
    if (bt && H5AC_unprotect(f, dxpl_id, H5AC_BLTR, addr, bt, H5AC__DIRTIED_FLAG | H5AC__DELETED_FLAG) < 0)
        HDONE_ERROR(H5E_BLKTRK, H5E_CANTUNPROTECT, FAIL, "unable to release block tracker info")
    
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5BT_remove() */