[svn-r14363] Description:

	Refactor file space allocation routines into separate source module.

Tested on:
        FreeBSD/32 6.2 (duty) in debug mode
        Mac OS X/32 10.4.10 (amazon) in debug mode

1 files changed, 1738 insertions, 0 deletions

diff --git a/src/H5FDspace.c b/src/H5FDspace.c
new file mode 100644
index 0000000..7bd72cc
--- /dev/null
+++ b/src/H5FDspace.c
@@ -0,0 +1,1738 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * 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:		H5FDspace.c
+ *			Jan  3 2008
+ *			Quincey Koziol <koziol@hdfgroup.org>
+ *
+ * Purpose:		Space allocation routines for the file.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#define H5FD_PACKAGE		/*suppress error about including H5FDpkg  */
+
+/* Interface initialization */
+#define H5_INTERFACE_INIT_FUNC	H5FD_space_init_interface
+
+
+/***********/
+/* Headers */
+/***********/
+#include "H5private.h"		/* Generic Functions			*/
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5Fprivate.h"         /* File access				*/
+#include "H5FDpkg.h"		/* File Drivers				*/
+#include "H5FDmulti.h"		/* Usage-partitioned file family	*/
+#include "H5MMprivate.h"	/* Memory management			*/
+
+
+/****************/
+/* Local Macros */
+/****************/
+
+/* Define this to display information about file allocations */
+/* #define H5FD_ALLOC_DEBUG */
+
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+
+/********************/
+/* Package Typedefs */
+/********************/
+
+
+/********************/
+/* Local Prototypes */
+/********************/
+static haddr_t H5FD_alloc_from_free_list(H5FD_t *file, H5FD_mem_t type,
+    hsize_t size);
+static haddr_t H5FD_aggr_alloc(H5FD_t *file, H5FD_blk_aggr_t *aggr,
+    H5FD_blk_aggr_t *other_aggr, H5FD_mem_t type, hid_t dxpl_id, hsize_t size);
+static herr_t H5FD_aggr_adjoin(const H5FD_t *file, H5FD_blk_aggr_t *aggr,
+    H5FD_free_t *last);
+static htri_t H5FD_aggr_can_extend(const H5FD_t *file, const H5FD_blk_aggr_t *aggr,
+    haddr_t eoa, haddr_t end);
+static herr_t H5FD_aggr_shift(H5FD_blk_aggr_t *aggr, hsize_t extra);
+static herr_t H5FD_aggr_query(const H5FD_t *file, const H5FD_blk_aggr_t *aggr,
+    haddr_t *addr, hsize_t *size);
+static haddr_t H5FD_real_alloc(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, hsize_t size);
+static haddr_t H5FD_update_eoa(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, hsize_t size);
+
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+
+/*******************/
+/* Local Variables */
+/*******************/
+
+/* Declare a free list to manage the H5FD_free_t struct */
+H5FL_DEFINE(H5FD_free_t);
+
+/* Declare a PQ free list to manage the metadata accumulator buffer */
+H5FL_BLK_DEFINE(meta_accum);
+
+
+
+/*--------------------------------------------------------------------------
+NAME
+   H5FD_space_init_interface -- Initialize interface-specific information
+USAGE
+    herr_t H5FD_space_init_interface()
+
+RETURNS
+    Non-negative on success/Negative on failure
+DESCRIPTION
+    Initializes any interface-specific data or routines.  (Just calls
+    H5FD_init_iterface currently).
+
+--------------------------------------------------------------------------*/
+static herr_t
+H5FD_space_init_interface(void)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_space_init_interface)
+
+    FUNC_LEAVE_NOAPI(H5FD_init())
+} /* H5FD_space_init_interface() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_free_freelist
+ *
+ * Purpose:     Split off from H5FD_close(). Free the elements in the
+ *              free list for this file driver.
+ *
+ * Return:      Success:    SUCCEED
+ *              Failure:    Never fails
+ *
+ * Programmer:  Bill Wendling
+ *              17. February 2003
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FD_free_freelist(H5FD_t *file)
+{
+    H5FD_mem_t  i;
+#ifdef H5FD_ALLOC_DEBUG
+    unsigned    nblocks = 0;
+    hsize_t     nbytes = 0;
+#endif  /* H5FD_ALLOC_DEBUG */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_free_freelist)
+
+    /* check args */
+    HDassert(file && file->cls);
+
+    /*
+     * Free all free-lists, leaking any memory thus described. Also leaks
+     * file space allocated but not used when metadata aggregation is
+     * turned on.
+     */
+    for(i = H5FD_MEM_DEFAULT; i < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, i)) {
+        H5FD_free_t *cur, *next;
+
+        for( cur = file->fl[i]; cur; cur = next) {
+#ifdef H5FD_ALLOC_DEBUG
+            ++nblocks;
+            nbytes += cur->size;
+#endif  /* H5FD_ALLOC_DEBUG */
+            next = cur->next;
+            H5FL_FREE(H5FD_free_t, cur);
+        } /* end for */
+
+        file->fl[i] = NULL;
+    } /* end for */
+
+#ifdef H5FD_ALLOC_DEBUG
+    if(nblocks)
+        HDfprintf(stderr, "%s: leaked %Hu bytes of file memory in %u blocks\n",
+                  "H5FD_free_freelist", nbytes, nblocks);
+#endif  /* H5FD_ALLOC_DEBUG */
+
+    /* Check if we need to reset the metadata accumulator information */
+    if(file->feature_flags & H5FD_FEAT_ACCUMULATE_METADATA) {
+        /* Free the buffer */
+        if(file->meta_accum)
+            file->meta_accum = H5FL_BLK_FREE(meta_accum, file->meta_accum);
+
+        /* Reset the buffer sizes & location */
+        file->accum_buf_size = file->accum_size = 0;
+        file->accum_loc = HADDR_UNDEF;
+        file->accum_dirty = 0;
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5FD_free_freelist() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_alloc
+ *
+ * Purpose:     Private version of H5FDalloc().
+ *
+ * Return:      Success:    The format address of the new file memory.
+ *              Failure:    The undefined address HADDR_UNDEF
+ *
+ * Programmer:  Robb Matzke
+ *              Wednesday, August  4, 1999
+ *
+ *-------------------------------------------------------------------------
+ */
+haddr_t
+H5FD_alloc(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, hsize_t size)
+{
+    haddr_t     ret_value = HADDR_UNDEF;
+
+    FUNC_ENTER_NOAPI(H5FD_alloc, HADDR_UNDEF)
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: type = %u, size = %Hu\n", FUNC, (unsigned)type, size);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    /* check args */
+    assert(file);
+    assert(file->cls);
+    assert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    assert(size > 0);
+
+#ifdef H5F_DEBUG
+    if(H5DEBUG(F))
+	HDfprintf(H5DEBUG(F), "%s: alignment=%Hd, threshold=%Hd, size=%Hd\n",
+                  FUNC, file->alignment, file->threshold, size);
+#endif  /* H5F_DEBUG */
+
+    /* Try to allocate from the free list first */
+    if((ret_value = H5FD_alloc_from_free_list(file, type, size)) != HADDR_UNDEF)
+        HGOTO_DONE(ret_value)
+
+#ifdef H5F_DEBUG
+    if(H5DEBUG(F))
+	HDfprintf(H5DEBUG(F), "%s: Could not allocate from freelists\n", FUNC);
+#endif  /* H5F_DEBUG */
+
+    if(type != H5FD_MEM_DRAW) {
+        /* Handle metadata differently from "raw" data */
+        if(HADDR_UNDEF == (ret_value = H5FD_aggr_alloc(file, &(file->meta_aggr), &(file->sdata_aggr), type, dxpl_id, size)))
+            HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate metadata")
+    } /* end if */
+    else {
+        /* Allocate "raw" data */
+        if(HADDR_UNDEF == (ret_value = H5FD_aggr_alloc(file, &(file->sdata_aggr), &(file->meta_aggr), type, dxpl_id, size)))
+            HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate raw data")
+    } /* end else */
+
+done:
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
+#endif /* H5FD_ALLOC_DEBUG */
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_alloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_alloc_from_free_list
+ *
+ * Purpose:     Try to allocate SIZE bytes of memory from the free list
+ *              if possible.
+ *
+ *              This is split from H5FD_alloc().
+ *
+ * Return:      Success:    The format address of the new file memory.
+ *              Failure:    The undefined address HADDR_UNDEF
+ *
+ * Programmer:  Bill Wendling
+ *              02. December, 2002
+ *
+ *-------------------------------------------------------------------------
+ */
+static haddr_t
+H5FD_alloc_from_free_list(H5FD_t *file, H5FD_mem_t type, hsize_t size)
+{
+    H5FD_mem_t mapped_type;
+    haddr_t ret_value = HADDR_UNDEF;
+
+    FUNC_ENTER_NOAPI(H5FD_alloc_from_free_list, HADDR_UNDEF)
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: type = %u, size = %Hu\n", FUNC, (unsigned)type, size);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    assert(file);
+    assert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    assert(size > 0);
+
+    /* Map the allocation request to a free list */
+    if(H5FD_MEM_DEFAULT == file->cls->fl_map[type])
+        mapped_type = type;
+    else
+        mapped_type = file->cls->fl_map[type];
+
+    /*
+     * Try to satisfy the request from the free list. Only perform the
+     * search if the free list has the potential of satisfying the
+     * request.
+     *
+     * Here, aligned requests are requests that are >= threshold and
+     * alignment > 1.
+     *
+     * For non-aligned request, first try to find an exact match,
+     * otherwise use the best match which is the smallest size that meets
+     * the requested size.
+     *
+     * For aligned address request, find a block in the following order
+     * of preferences:
+     *
+     *   1. block address is aligned and exact match in size;
+     *   2. block address is aligned with smallest size > requested size;
+     *   3. block address is not aligned with smallest size >= requested size.
+     */
+    if(mapped_type >= H5FD_MEM_DEFAULT && (file->maxsize == 0 || size <= file->maxsize)) {
+        H5FD_free_t    *prev = NULL, *best = NULL;
+        H5FD_free_t    *cur = file->fl[mapped_type];
+        hbool_t         found_aligned = FALSE;
+        hbool_t         need_aligned;
+        hsize_t         head;
+
+        need_aligned = file->alignment > 1 && size >= file->threshold;
+
+        while(cur) {
+            if(cur->size > file->maxsize)
+                file->maxsize = cur->size;
+
+            if(need_aligned) {
+                if((head = cur->addr % file->alignment) == 0) {
+                    /*
+                     * Aligned address
+                     */
+                    if(cur->size >= size) {
+                        if(cur->size == size) {
+                            /* exact match */
+                            ret_value = cur->addr;
+
+                            /*
+                             * Make certain we don't hand out a block of raw data
+                             * from the free list which overlaps with the metadata
+                             * aggregation buffer (if it's turned on)
+                             */
+                            if(type == H5FD_MEM_DRAW &&
+                                    (file->feature_flags & H5FD_FEAT_ACCUMULATE_METADATA) &&
+                                    H5F_addr_overlap(ret_value, size,
+                                                     file->accum_loc, file->accum_size)) {
+                                ret_value = HADDR_UNDEF;
+                            } else {
+                                if(prev)
+                                    prev->next = cur->next;
+                                else
+                                    file->fl[mapped_type] = cur->next;
+
+                                H5FL_FREE(H5FD_free_t, cur);
+
+                                if(size == file->maxsize)
+                                    file->maxsize = 0;  /*unknown*/
+
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Exact size match (aligned)\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+                                HGOTO_DONE(ret_value)
+                            }
+                        }
+                        else
+                            /* Favor smallest block, that's closest to the beginning of the file */
+                            if(!best || !found_aligned || cur->size < best->size ||
+                                    (cur->size == best->size && H5F_addr_lt(cur->addr, best->addr))) {
+                                best = cur;
+                                found_aligned = TRUE;
+                            }
+                    } /* end if */
+                } else {
+                    /*
+                     * Non-aligned address
+                     *
+                     * Check to see if this block is big enough to skip
+                     * to the next aligned address and is still big
+                     * enough for the requested size.  The extra
+                     * (cur->size > head) is for preventing unsigned
+                     * underflow.  (This could be improved by checking for
+                     * an exact match after excluding the head.  Such
+                     * match is as good as the found_aligned case above.)
+                     */
+                    head = file->alignment - head;	/* actual head size */
+
+                    if(!found_aligned && cur->size > head && cur->size-head >= size) {
+                        /* Favor smallest block, that's closest to the beginning of the file */
+                        if(!best || cur->size < best->size ||
+                                (cur->size == best->size && H5F_addr_lt(cur->addr, best->addr)))
+                            best = cur;
+                    } /* end if */
+                } /* end else */
+            } else {
+                /* !need_aligned */
+                if(cur->size >= size) {
+                    if(cur->size == size) {
+                        /* exact match */
+                        ret_value = cur->addr;
+
+                        /*
+                         * Make certain we don't hand out a block of raw data
+                         * from the free list which overlaps with the metadata
+                         * aggregation buffer (if it's turned on)
+                         */
+                        if(type == H5FD_MEM_DRAW &&
+                                (file->feature_flags & H5FD_FEAT_ACCUMULATE_METADATA) &&
+                                H5F_addr_overlap(ret_value, size, file->accum_loc,
+                                                 file->accum_size)) {
+                            ret_value = HADDR_UNDEF;
+                        } else {
+                            if(prev)
+                                prev->next = cur->next;
+                            else
+                                file->fl[mapped_type] = cur->next;
+
+                            H5FL_FREE(H5FD_free_t, cur);
+
+                            if(size == file->maxsize)
+                                file->maxsize = 0;  /*unknown*/
+
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Exact size match (unaligned)\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+                            HGOTO_DONE(ret_value)
+                        }
+                    } /* end if */
+                    else {
+                        /* Favor smallest block, that's closest to the beginning of the file */
+                        if(!best || cur->size < best->size ||
+                                (cur->size == best->size && H5F_addr_lt(cur->addr, best->addr)))
+                            best = cur;
+                    } /* end else */
+                } /* end if */
+            } /* end else */
+
+            prev = cur;
+            cur = cur->next;
+        } /* end while */
+
+        /* Couldn't find exact match, use best fitting piece found */
+        if(best) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Splitting %Hu byte sized block\n", FUNC, best->size);
+#endif /* H5FD_ALLOC_DEBUG */
+            if(best->size == file->maxsize)
+                file->maxsize = 0;  /*unknown*/
+
+            if(!need_aligned || found_aligned) {
+                /* free only tail */
+                ret_value = best->addr;
+
+                /*
+                 * Make certain we don't hand out a block of raw data
+                 * from the free list which overlaps with the metadata
+                 * aggregation buffer (if it's turned on)
+                 */
+                if(type == H5FD_MEM_DRAW &&
+                        (file->feature_flags & H5FD_FEAT_ACCUMULATE_METADATA) &&
+                        H5F_addr_overlap(ret_value, size, file->accum_loc,
+                                         file->accum_size)) {
+                    ret_value = HADDR_UNDEF;
+                } else {
+                    best->addr += size;     /* Reduce size of block on free list */
+                    best->size -= size;
+                    HGOTO_DONE(ret_value)
+                }
+            } else {
+                /*
+                 * Split into 3 pieces. Keep the the head and tail in the
+                 * freelist.
+                 */
+                H5FD_free_t *tmp = NULL;
+
+                head = file->alignment - (best->addr % file->alignment);
+                ret_value = best->addr + head;
+
+                /*
+                 * Make certain we don't hand out a block of raw data
+                 * from the free list which overlaps with the metadata
+                 * aggregation buffer (if it's turned on)
+                 */
+                if(type == H5FD_MEM_DRAW &&
+                        (file->feature_flags & H5FD_FEAT_ACCUMULATE_METADATA) &&
+                        H5F_addr_overlap(ret_value, size, file->accum_loc, file->accum_size)) {
+                    ret_value = HADDR_UNDEF;
+                } else {
+                    /* Attempt to allocate memory for temporary node */
+                    if((tmp = H5FL_MALLOC(H5FD_free_t))==NULL)
+                        HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "free block allocation failed")
+
+                    if((tmp->size = (best->size - (head + size)))!=0) {
+                        tmp->addr = best->addr + (head + size);
+                        tmp->next = best->next;
+                        best->next = tmp;
+                    } else {
+                        /* no tail piece */
+                        H5FL_FREE(H5FD_free_t,tmp);
+                    }
+
+                    best->size = head;
+                    HGOTO_DONE(ret_value)
+                } /* end else */
+            } /* end else */
+        } /* end if */
+    } /* end if */
+
+done:
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
+#endif /* H5FD_ALLOC_DEBUG */
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_alloc_from_free_list() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_aggr_alloc
+ *
+ * Purpose:     Try to allocate SIZE bytes of memory from an aggregator
+ *              block if possible.
+ *
+ *              This is split from H5FD_alloc().
+ *
+ * Return:      Success:    The format address of the new file memory.
+ *              Failure:    The undefined address HADDR_UNDEF
+ *
+ * Programmer:  Bill Wendling
+ *              2. December, 2002
+ *
+ *-------------------------------------------------------------------------
+ */
+static haddr_t
+H5FD_aggr_alloc(H5FD_t *file, H5FD_blk_aggr_t *aggr, H5FD_blk_aggr_t *other_aggr,
+    H5FD_mem_t type, hid_t dxpl_id, hsize_t size)
+{
+    haddr_t ret_value;          /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5FD_aggr_alloc)
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: type = %u, size = %Hu\n", FUNC, (unsigned)type, size);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    /* check args */
+    HDassert(file);
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+    HDassert(other_aggr);
+    HDassert(other_aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || other_aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+    HDassert(other_aggr->feature_flag != aggr->feature_flag);
+    HDassert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    HDassert(size > 0);
+
+    /*
+     * If the aggregation feature is enabled for this VFL
+     * driver, allocate "generic" space and sub-allocate out of
+     * that, if possible. Otherwise just allocate through
+     * H5FD_real_alloc()
+     */
+    if(file->feature_flags & aggr->feature_flag) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: aggr = {%a, %Hu, %Hu}\n", FUNC, aggr->addr, aggr->tot_size, aggr->size);
+#endif /* H5FD_ALLOC_DEBUG */
+        /* Check if the space requested is larger than the space left in the block */
+        if(size > aggr->size) {
+            haddr_t new_space;   /* Address for newly allocated space */
+
+            /* Check if the block asked for is too large for 'normal' aggregator block */
+            if(size >= aggr->alloc_size) {
+                /* Allocate more room for this new block the regular way */
+                if(HADDR_UNDEF == (new_space = H5FD_real_alloc(file, type, dxpl_id, size)))
+                    HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate aggregation block")
+
+                /* Check if the new space is at the end of the current block */
+                if((aggr->addr + aggr->size) == new_space) {
+                    /*
+                     * Treat the allocation request as if the current block
+                     * grew by the amount allocated and just update the address.
+                     *
+                     * Don't bother updating the block's size since it will
+                     * just grow and shrink by the same amount.
+                     *
+                     * _Do_ add to the total size aggregated.
+                     *
+                     */
+                    ret_value = aggr->addr;
+                    aggr->addr += size;
+                    aggr->tot_size += size;
+                } /* end if */
+                else {
+                    /* Check if the new space is at the end of the _other_ block */
+                    if(other_aggr->size > 0 && (other_aggr->addr + other_aggr->size) == new_space) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: New block is at end of 'other' block: other_aggr = {%a, %Hu, %Hu}\n", FUNC, other_aggr->addr, other_aggr->tot_size, other_aggr->size);
+#endif /* H5FD_ALLOC_DEBUG */
+                        /* If the other block has used at least the
+                         *      'allocation' amount for that block, shift the
+                         *      newly allocated space down over the remainder
+                         *      in the 'other block', shift the 'other block'
+                         *      up by the same amount and free it.  (Which
+                         *      should amount to "bubbling" the remainder in
+                         *      the 'other block' to the end of the file and
+                         *      then "popping" the bubble by shrinking the
+                         *      file)
+                         */
+                        if((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size) {
+                            H5FD_mem_t alloc_type = (other_aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA ? H5FD_MEM_DEFAULT : H5FD_MEM_DRAW);      /* Type of file memory to work with */
+                            haddr_t free_addr = (new_space + size) - other_aggr->size;   /* Address of free space in 'other block' shifted toward end of the file */
+                            hsize_t free_size = other_aggr->size;               /* Size of the free space in 'other block' */
+
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Freeing 'other' block\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+                            /* Reset 'other' block's info */
+                            other_aggr->addr = 0;
+                            other_aggr->tot_size = 0;
+                            other_aggr->size = 0;
+
+                            /* Shift newly allocated space down */
+                            new_space -= free_size;
+
+                            /* Return the unused portion of the 'other' block to a free list */
+                            if(H5FD_free(file, alloc_type, dxpl_id, free_addr, free_size) < 0)
+                                HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
+                        } /* end if */
+                    } /* end if */
+
+                    /* Use the new space allocated, leaving the old block */
+                    ret_value = new_space;
+                } /* end else */
+            } /* end if */
+            else {
+                H5FD_mem_t alloc_type = (aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA ? H5FD_MEM_DEFAULT : H5FD_MEM_DRAW);      /* Type of file memory to work with */
+
+                /* Allocate another block */
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Allocating block\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+                if(HADDR_UNDEF == (new_space = H5FD_real_alloc(file, alloc_type, dxpl_id, aggr->alloc_size)))
+                    HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate aggregation block")
+
+                /* Check if the new space is at the end of the current block */
+                if(aggr->addr + aggr->size == new_space) {
+                    aggr->size += aggr->alloc_size;
+                    aggr->tot_size += aggr->alloc_size;
+                } /* end if */
+                else {
+                    hsize_t new_size;   /* Size of new aggregator block */
+
+                    /* Return the unused portion of the block to a free list */
+                    if(aggr->size > 0)
+                        if(H5FD_free(file, alloc_type, dxpl_id, aggr->addr, aggr->size) < 0)
+                            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
+
+                    /* Check if the new space is at the end of the _other_ block */
+                    if(other_aggr->size > 0 && (other_aggr->addr + other_aggr->size) == new_space) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: New block is at end of 'other' block: other_aggr = {%a, %Hu, %Hu}\n", FUNC, other_aggr->addr, other_aggr->tot_size, other_aggr->size);
+#endif /* H5FD_ALLOC_DEBUG */
+#ifdef QAK
+                        /* If the other block has used at least the
+                         *      'allocation' amount for that block, give the
+                         *      remaining free space in the 'other' block to
+                         *      the new space allocated for 'this' block.
+                         */
+                        if((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Absorbing 'other' block\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+                            /* Absorb the remaining free space into newly allocated block */
+                            new_space -= other_aggr->size;
+                            new_size = aggr->alloc_size + other_aggr->size;
+
+                            /* Reset the info for the 'other' block */
+                            other_aggr->addr = 0;
+                            other_aggr->tot_size = 0;
+                            other_aggr->size = 0;
+                        } /* end if */
+                        else
+                            new_size = aggr->alloc_size;
+#else /* QAK */
+                        /* If the other block has used at least the
+                         *      'allocation' amount for that block, shift the
+                         *      newly allocated space down over the remainder
+                         *      in the 'other block', shift the 'other block'
+                         *      up by the same amount and free it.  (Which
+                         *      should amount to "bubbling" the remainder in
+                         *      the 'other block' to the end of the file and
+                         *      then "popping" the bubble by shrinking the
+                         *      file)
+                         */
+                        if((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size) {
+                            H5FD_mem_t other_type = (other_aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA ? H5FD_MEM_DEFAULT : H5FD_MEM_DRAW);      /* Type of file memory to work with */
+                            haddr_t free_addr = (new_space + aggr->alloc_size) - other_aggr->size;   /* Address of free space in 'other block' shifted toward end of the file */
+                            hsize_t free_size = other_aggr->size;               /* Size of the free space in 'other block' */
+
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Freeing 'other' block\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+                            /* Reset 'other' block's info */
+                            other_aggr->addr = 0;
+                            other_aggr->tot_size = 0;
+                            other_aggr->size = 0;
+
+                            /* Shift newly allocated space down */
+                            new_space -= free_size;
+
+                            /* Return the unused portion of the 'other' block to a free list */
+                            if(H5FD_free(file, other_type, dxpl_id, free_addr, free_size) < 0)
+                                HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
+                        } /* end if */
+                        new_size = aggr->alloc_size;
+#endif /* QAK */
+                    } /* end if */
+                    else
+                        new_size = aggr->alloc_size;
+
+                    /* Point the aggregator at the newly allocated block */
+                    aggr->addr = new_space;
+                    aggr->size = new_size;
+                    aggr->tot_size = new_size;
+                } /* end else */
+
+                /* Allocate space out of the metadata block */
+                ret_value = aggr->addr;
+                aggr->size -= size;
+                aggr->addr += size;
+            } /* end else */
+        } /* end if */
+        else {
+            /* Allocate space out of the block */
+            ret_value = aggr->addr;
+            aggr->size -= size;
+            aggr->addr += size;
+        }
+    } /* end if */
+    else {
+        /* Allocate data the regular way */
+        if(HADDR_UNDEF == (ret_value = H5FD_real_alloc(file, type, dxpl_id, size)))
+            HGOTO_ERROR(H5E_VFL, H5E_CANTALLOC, HADDR_UNDEF, "can't allocate file space")
+    } /* end else */
+
+done:
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
+#endif /* H5FD_ALLOC_DEBUG */
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_aggr_alloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_aggr_adjoin
+ *
+ * Purpose:     Check if a newly freed block of space in the file adjoins an
+ *              aggregator block
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, December 13, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_aggr_adjoin(const H5FD_t *file, H5FD_blk_aggr_t *aggr, H5FD_free_t *last)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_aggr_adjoin)
+
+    /* Check args */
+    HDassert(file);
+    HDassert(file->cls);
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+    HDassert(last);
+
+    /* Check if this free block adjoins the aggregator */
+    if((file->feature_flags & aggr->feature_flag) && aggr->size > 0) {
+        hbool_t adjoins = FALSE;    /* Whether the block adjoined the aggregator */
+
+        /* Does the newly freed space adjoin the end of the aggregator */
+        if((aggr->addr + aggr->size) == last->addr) {
+            last->addr = aggr->addr;
+            adjoins = TRUE;
+        } /* end if */
+        /* Does the newly freed space adjoin the beginning of the aggregator */
+        else if((last->addr + last->size) == aggr->addr)
+            adjoins = TRUE;
+
+        /* Reset aggregator information, if adjoined */
+        if(adjoins) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Adjoined flag = %lx aggregator\n", "H5FD_aggr_adjoin", aggr->feature_flag);
+#endif /* H5FD_ALLOC_DEBUG */
+            last->size += aggr->size;
+            aggr->addr = 0;
+            aggr->size = 0;
+        } /* end if */
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5FD_aggr_adjoin() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_aggr_can_extend
+ *
+ * Purpose:     Check is an aggregator block can be extended
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, December 13, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static htri_t
+H5FD_aggr_can_extend(const H5FD_t *file, const H5FD_blk_aggr_t *aggr, haddr_t eoa,
+    haddr_t end)
+{
+    htri_t ret_value = FALSE;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_aggr_can_extend)
+
+    /* Check args */
+    HDassert(file);
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+
+    /* Check if this aggregator is active */
+    if(file->feature_flags & aggr->feature_flag) {
+        /* If the aggregator block is at the end of the file, and the block to
+         * test adjoins the beginning of the aggregator block, then it's
+         * extendable
+         */
+        if((aggr->addr + aggr->size) == eoa && end == aggr->addr)
+            HGOTO_DONE(TRUE)
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_aggr_can_extend() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_aggr_extend
+ *
+ * Purpose:     Shift an aggregator block in the file
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, December 13, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_aggr_shift(H5FD_blk_aggr_t *aggr, hsize_t extra)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_aggr_shift)
+
+    /* Check args */
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+
+    /* Shift the aggregator block by the extra amount */
+    aggr->addr += extra;
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5FD_aggr_shift() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_aggr_query
+ *
+ * Purpose:     Query a block aggregator's current address & size info
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, December 13, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_aggr_query(const H5FD_t *file, const H5FD_blk_aggr_t *aggr, haddr_t *addr,
+    hsize_t *size)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5FD_aggr_query)
+
+    /* Check args */
+    HDassert(file);
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+
+    /* Check if this aggregator is active */
+    if(file->feature_flags & aggr->feature_flag) {
+        *addr = aggr->addr;
+        *size = aggr->size;
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5FD_aggr_query() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_aggr_reset
+ *
+ * Purpose:     Reset a block aggregator, returning any space back to file
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, December 13, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FD_aggr_reset(H5FD_t *file, H5FD_blk_aggr_t *aggr, hid_t dxpl_id)
+{
+    H5FD_mem_t alloc_type;      /* Type of file memory to work with */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_aggr_reset, FAIL)
+
+    /* Check args */
+    HDassert(file);
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+
+    /* Set the type of memory in the file */
+    alloc_type = (aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA ? H5FD_MEM_DEFAULT : H5FD_MEM_DRAW);      /* Type of file memory to work with */
+
+    /* Check if this aggregator is active */
+    if(file->feature_flags & aggr->feature_flag) {
+        /* Return the unused portion of the metadata block to a free list */
+        if(aggr->size > 0)
+            if(H5FD_free(file, alloc_type, dxpl_id, aggr->addr, aggr->size) < 0)
+                HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "can't free aggregator block")
+
+        /* Reset aggregator block information */
+        aggr->tot_size = 0;
+        aggr->addr = 0;
+        aggr->size = 0;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_aggr_reset() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_real_alloc
+ *
+ * Purpose:	Double private version of H5FDalloc() :-)
+ *
+ * Return:	Success:	The format address of the new file memory.
+ *		Failure:	The undefined address HADDR_UNDEF
+ *
+ * Programmer:	Quincey Koziol
+ *              Friday, August 25, 2000
+ *
+ *-------------------------------------------------------------------------
+ */
+static haddr_t
+H5FD_real_alloc(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, hsize_t size)
+{
+    haddr_t ret_value = HADDR_UNDEF;
+
+    FUNC_ENTER_NOAPI_NOINIT(H5FD_real_alloc)
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: type = %u, size = %Hu\n", FUNC, (unsigned)type, size);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    /* check args */
+    assert(file);
+    assert(file->cls);
+    assert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    assert(size > 0);
+
+    /*
+     * Dispatch to driver `alloc' callback or extend the end-of-address
+     * marker
+     */
+    if(file->cls->alloc) {
+        if((ret_value = (file->cls->alloc)(file, type, dxpl_id, size)) == HADDR_UNDEF)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "driver allocation request failed")
+    } else {
+        if((ret_value = H5FD_update_eoa(file, type, dxpl_id, size)) == HADDR_UNDEF)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "driver eoa update request failed")
+    }
+
+done:
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: ret_value = %a\n", FUNC, ret_value);
+#endif /* H5FD_ALLOC_DEBUG */
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_real_alloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_update_eoa
+ *
+ * Purpose:     Update the EOA field of the file's memory.
+ *
+ *              This was split off from the H5FD_real_alloc function to
+ *              make life easier for all.
+ *
+ * Return:      Success:    The format address of the new file memory.
+ *              Failure:    The undefined address HADDR_UNDEF
+ *
+ * Programmer:  Bill Wendling
+ *              Wednesday, 04. December, 2002
+ *
+ *-------------------------------------------------------------------------
+ */
+static haddr_t
+H5FD_update_eoa(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, hsize_t size)
+{
+    haddr_t eoa, oldeoa = 0;
+    hsize_t wasted;
+    haddr_t ret_value = HADDR_UNDEF;
+
+    FUNC_ENTER_NOAPI_NOINIT(H5FD_update_eoa)
+
+    /* check args */
+    assert(file);
+    assert(file->cls);
+    assert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+    assert(size > 0);
+
+    eoa = file->cls->get_eoa(file, type);
+
+#ifdef H5F_DEBUG
+    if(file->alignment * file->threshold != 1 && H5DEBUG(F))
+        HDfprintf(H5DEBUG(F),
+                  "%s: alignment=%Hd, threshold=%Hd, size=%Hd, Begin eoa=%a\n",
+                  FUNC, file->alignment, file->threshold, size, eoa);
+#endif  /* H5F_DEBUG */
+
+    /* Wasted is 0 if not exceeding threshold or eoa happens to be aligned */
+    wasted = (size >= file->threshold) ? (eoa % file->alignment) : 0;
+    if(wasted) {
+        wasted = file->alignment - wasted;      /* actual waste                 */
+        oldeoa = eoa;                           /* save it for later freeing    */
+
+        /* Advance eoa to the next alignment by allocating the wasted */
+        if(H5F_addr_overflow(eoa, size) || (eoa + wasted) > file->maxaddr)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "file allocation request failed")
+
+        eoa += wasted;
+
+        if(file->cls->set_eoa(file, type, eoa) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "file allocation request failed")
+    } /* end if */
+
+    /* allocate the aligned memory */
+    if(H5F_addr_overflow(eoa, size) || eoa + size > file->maxaddr)
+        HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "file allocation request failed")
+
+    ret_value = eoa;
+    eoa += size;
+
+    if(file->cls->set_eoa(file, type, eoa) < 0)
+        HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, HADDR_UNDEF, "file allocation request failed")
+
+    /* Free the wasted memory */
+    if(wasted) {
+        if(H5FD_free(file, type, dxpl_id, oldeoa, wasted) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "file deallocation request failed")
+    } /* end if */
+
+#ifdef H5F_DEBUG
+    if(file->alignment * file->threshold != 1 && H5DEBUG(F))
+        HDfprintf(H5DEBUG(F),
+                  "%s: ret_value=%a, wasted=%Hd, Ended eoa=%a\n",
+                  FUNC, ret_value, wasted, eoa);
+#endif  /* H5F_DEBUG */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_update_eoa() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_free
+ *
+ * Purpose:     Private version of H5FDfree()
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Robb Matzke
+ *              Wednesday, August  4, 1999
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FD_free(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, hsize_t size)
+{
+    H5FD_mem_t		mapped_type;
+    herr_t      ret_value = SUCCEED;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_free, FAIL)
+
+    /* Check args */
+    HDassert(file);
+    HDassert(file->cls);
+    HDassert(type >= H5FD_MEM_DEFAULT && type < H5FD_MEM_NTYPES);
+
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: type = %u, addr = %a, size = %Hu\n", FUNC, (unsigned)type, addr, size);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    if(!H5F_addr_defined(addr) || addr > file->maxaddr ||
+            H5F_addr_overflow(addr, size) || (addr + size) > file->maxaddr)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid region")
+
+    /* Allow 0-sized free's to occur without penalty */
+    if(0 == size)
+        HGOTO_DONE(SUCCEED)
+
+    /* Map request type to free list */
+    if(H5FD_MEM_DEFAULT==file->cls->fl_map[type])
+        mapped_type = type;
+    else
+        mapped_type = file->cls->fl_map[type];
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: mapped_type = %u\n", FUNC, (unsigned)mapped_type);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    /*
+     * If the request maps to a free list then add memory to the free list
+     * without ever telling the driver that it was freed.  Otherwise let the
+     * driver deallocate the memory.
+     */
+    if(mapped_type >= H5FD_MEM_DEFAULT) {
+        H5FD_free_t *last;          /* Last merged node */
+        H5FD_free_t *last_prev = NULL;/* Pointer to node before merged node */
+        H5FD_free_t *curr;          /* Current free block being inspected */
+        H5FD_free_t *prev;          /* Previous free block being inspected */
+
+        /* Adjust the metadata accumulator to remove the freed block, if it overlaps */
+        if((file->feature_flags&H5FD_FEAT_ACCUMULATE_METADATA)
+                && H5F_addr_overlap(addr, size, file->accum_loc, file->accum_size)) {
+            size_t overlap_size;        /* Size of overlap with accumulator */
+
+            /* Check for overlapping the beginning of the accumulator */
+            if(H5F_addr_le(addr, file->accum_loc)) {
+                /* Check for completely overlapping the accumulator */
+                if(H5F_addr_ge(addr + size, file->accum_loc + file->accum_size)) {
+                    /* Reset the entire accumulator */
+                    file->accum_loc=HADDR_UNDEF;
+                    file->accum_size=FALSE;
+                    file->accum_dirty=FALSE;
+                } /* end if */
+                /* Block to free must end within the accumulator */
+                else {
+                    size_t new_accum_size;      /* Size of new accumulator buffer */
+
+                    /* Calculate the size of the overlap with the accumulator, etc. */
+                    H5_ASSIGN_OVERFLOW(overlap_size,(addr+size)-file->accum_loc,haddr_t,size_t);
+                    new_accum_size=file->accum_size-overlap_size;
+
+                    /* Move the accumulator buffer information to eliminate the freed block */
+                    HDmemmove(file->meta_accum,file->meta_accum+overlap_size,new_accum_size);
+
+                    /* Adjust the accumulator information */
+                    file->accum_loc+=overlap_size;
+                    file->accum_size=new_accum_size;
+                } /* end else */
+            } /* end if */
+            /* Block to free must start within the accumulator */
+            else {
+                /* Calculate the size of the overlap with the accumulator */
+                H5_ASSIGN_OVERFLOW(overlap_size,(file->accum_loc+file->accum_size)-addr,haddr_t,size_t);
+
+                /* Block to free is in the middle of the accumulator */
+                if(H5F_addr_lt((addr + size), file->accum_loc + file->accum_size)) {
+                    haddr_t tail_addr;
+                    size_t tail_size;
+
+                    /* Calculate the address & size of the tail to write */
+                    tail_addr=addr+size;
+                    H5_ASSIGN_OVERFLOW(tail_size,(file->accum_loc+file->accum_size)-tail_addr,haddr_t,size_t);
+
+                    /* Write out the part of the accumulator after the block to free */
+                    /* (Use the driver's write call directly - to avoid looping back and writing to metadata accumulator) */
+                    if((file->cls->write)(file, H5FD_MEM_DEFAULT, dxpl_id, tail_addr, tail_size, file->meta_accum+(tail_addr-file->accum_loc)) < 0)
+                        HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "file write request failed")
+                } /* end if */
+
+                /* Adjust the accumulator information */
+                file->accum_size=file->accum_size-overlap_size;
+            } /* end else */
+        } /* end if */
+
+        /* Scan through the existing blocks for the mapped type to see if we can extend one */
+        curr = file->fl[mapped_type];
+        last = prev = NULL;
+        while(curr != NULL) {
+            /* Check if the block to free adjoins the start of the current block */
+            if((addr + size) == curr->addr) {
+                /* If we previously found & merged a node, eliminate it from the list & free it */
+                if(last != NULL) {
+                    /* Check if there was a previous block in the list */
+                    if(last_prev != NULL)
+                        /* Eliminate the merged block from the list */
+                        last_prev->next = last->next;
+                    /* No previous block, this must be the head of the list */
+                    else
+                        /* Eliminate the merged block from the list */
+                        file->fl[mapped_type] = last->next;
+
+                    /* Check for eliminating the block before the 'current' one */
+                    if(last == prev)
+                        prev = last_prev;
+
+                    /* Free the memory for the merged block */
+                    H5FL_FREE(H5FD_free_t, last);
+                } /* end if */
+
+                /* Adjust the address and size of the block found */
+                curr->addr = addr;
+                curr->size += size;
+
+                /* Adjust the information about to memory block to include the merged block */
+                addr = curr->addr;
+                size = curr->size;
+
+                /* Update the information about the merged node */
+                last = curr;
+                last_prev = prev;
+            } /* end if */
+            else {
+                /* Check if the block to free adjoins the end of the current block */
+                if((curr->addr + curr->size) == addr) {
+                    /* If we previously found & merged a node, eliminate it from the list & free it */
+                    if(last != NULL) {
+                        /* Check if there was a previous block in the list */
+                        if(last_prev != NULL)
+                            /* Eliminate the merged block from the list */
+                            last_prev->next = last->next;
+                        /* No previous block, this must be the head of the list */
+                        else
+                            /* Eliminate the merged block from the list */
+                            file->fl[mapped_type] = last->next;
+
+                        /* Check for eliminating the block before the 'current' one */
+                        if(last == prev)
+                            prev = last_prev;
+
+                        /* Free the memory for the merged block */
+                        H5FL_FREE(H5FD_free_t, last);
+                    } /* end if */
+
+                    /* Adjust the size of the block found */
+                    curr->size += size;
+
+                    /* Adjust the information about to memory block to include the merged block */
+                    addr = curr->addr;
+                    size = curr->size;
+
+                    /* Update the information about the merged node */
+                    last = curr;
+                    last_prev = prev;
+                } /* end if */
+            } /* end else */
+
+            /* Advance to next node in list */
+            prev = curr;
+            curr = curr->next;
+        } /* end while */
+
+        /* Check if we adjusted an existing block */
+        if(last != NULL) {
+            /* Move the node found to the front, if it wasn't already there */
+            if(last_prev != NULL) {
+                last_prev->next = last->next;
+                last->next = file->fl[mapped_type];
+                file->fl[mapped_type] = last;
+            } /* end if */
+        } /* end if */
+        else {
+            /* Allocate a new node to hold the free block's information */
+            if(NULL == (last = H5FL_MALLOC(H5FD_free_t)))
+                HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, FAIL, "can't allocate node for free space info")
+
+            last->addr = addr;
+            last->size = size;
+            last->next = file->fl[mapped_type];
+            file->fl[mapped_type] = last;
+        } /* end else */
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: mapped_type = %u, last = {%a, %Hu}\n", FUNC, (unsigned)mapped_type, last->addr, last->size);
+#endif /* H5FD_ALLOC_DEBUG */
+
+        /* Check if we increased the size of the largest block on the list */
+        file->maxsize = MAX(file->maxsize, last->size);
+
+        /* Check if this free block adjoins the "metadata aggregator" */
+        if(H5FD_aggr_adjoin(file, &(file->meta_aggr), last) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "aggregator deallocation request failed")
+
+        /* Check if this free block adjoins the "small data aggregator" */
+        if(H5FD_aggr_adjoin(file, &(file->sdata_aggr), last) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, FAIL, "aggregator deallocation request failed")
+
+        /* Check if this free block is at the end of file allocated space.
+         * Truncate it if this is true. */
+        if(file->cls->get_eoa) {
+            haddr_t     eoa;
+
+            eoa = file->cls->get_eoa(file, type);
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: eoa = %a\n", FUNC, eoa);
+#endif /* H5FD_ALLOC_DEBUG */
+            if(eoa == (last->addr + last->size)) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Reducing file size to = %a\n", FUNC, last->addr);
+#endif /* H5FD_ALLOC_DEBUG */
+                if(file->cls->set_eoa(file, type, last->addr) < 0)
+                    HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "set end of space allocation request failed")
+
+                /* Remove this free block from the list */
+                file->fl[mapped_type] = last->next;
+                if(file->maxsize == last->size)
+                    file->maxsize = 0; /*unknown*/
+                H5FL_FREE(H5FD_free_t, last);
+            } /* end if */
+        } /* end if */
+    } else if(file->cls->free) {
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: Letting VFD free space\n", FUNC);
+#endif /* H5FD_ALLOC_DEBUG */
+        if((file->cls->free)(file, type, dxpl_id, addr, size) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "driver free request failed")
+    } else {
+        /* leak memory */
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: LEAKED MEMORY!!! type = %u, addr = %a, size = %Hu\n", FUNC, (unsigned)type, addr, size);
+#endif /* H5FD_ALLOC_DEBUG */
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_free() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_realloc
+ *
+ * Purpose:	Private version of H5FDrealloc()
+ *
+ * Return:	Success:	New address of the block of memory, not
+ *				necessarily the same as the original address.
+ *		Failure:	HADDR_UNDEF
+ *
+ * Programmer:	Robb Matzke
+ *              Wednesday, August  4, 1999
+ *
+ *-------------------------------------------------------------------------
+ */
+haddr_t
+H5FD_realloc(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, haddr_t old_addr, hsize_t old_size,
+	     hsize_t new_size)
+{
+    haddr_t	new_addr=old_addr;
+    uint8_t	_buf[8192];
+    uint8_t	*buf=_buf;
+    haddr_t      ret_value;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_realloc, HADDR_UNDEF)
+
+    if(new_size == old_size) {
+        /*nothing to do*/
+    } else if(0 == old_size) {
+        /* allocate memory */
+        HDassert(!H5F_addr_defined(old_addr));
+        if(HADDR_UNDEF == (new_addr = H5FD_alloc(file, type, dxpl_id, new_size)))
+            HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, HADDR_UNDEF, "file allocation failed")
+    } else if(0==new_size) {
+        /* free memory */
+        HDassert(H5F_addr_defined(old_addr));
+        if(H5FD_free(file, type, dxpl_id, old_addr, old_size) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "file deallocation request failed")
+        new_addr = HADDR_UNDEF;
+    } else if(new_size<old_size) {
+        /* free the end of the block */
+        if(H5FD_free(file, type, dxpl_id, old_addr+old_size, old_size-new_size) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "file deallocation request failed")
+    } else {
+        /* move memory to new location */
+        /* Note!  This may fail if sizeof(hsize_t)>sizeof(size_t) and the
+         * object on disk is too large to read into a memory buffer all at one
+         * time.  This chunk of code would have to be re-written using a loop
+         * to move pieces of the realloced data through a fixed size buffer, etc.
+         * -QAK, 6/20/01
+         */
+        if(HADDR_UNDEF == (new_addr = H5FD_alloc(file, type, dxpl_id, new_size)))
+            HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, HADDR_UNDEF, "file allocation failed")
+        H5_CHECK_OVERFLOW(old_size,hsize_t,size_t);
+        if(old_size > sizeof(_buf) && NULL == (buf = H5MM_malloc((size_t)old_size))) {
+            (void)H5FD_free(file, type, dxpl_id, new_addr, new_size);
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, HADDR_UNDEF, "memory allocation failed")
+        } /* end if */
+        if(H5FD_read(file, type, dxpl_id, old_addr, (size_t)old_size, buf) < 0 ||
+                H5FD_write(file, type, dxpl_id, new_addr, (size_t)old_size, buf) < 0) {
+            (void)H5FD_free(file, type, dxpl_id, new_addr, new_size);
+            if(buf != _buf)
+                H5MM_xfree(buf);
+            HGOTO_ERROR(H5E_FILE, H5E_READERROR, HADDR_UNDEF, "unable to move file block")
+        } /* end if */
+
+        if(buf != _buf)
+            H5MM_xfree(buf);
+        if(H5FD_free(file, type, dxpl_id, old_addr, old_size) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTFREE, HADDR_UNDEF, "file deallocation request failed")
+    } /* end else */
+
+    /* Set return value */
+    ret_value = new_addr;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_realloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_can_extend
+ *
+ * Purpose:	Check if a block in the file can be extended.
+ *
+ * Return:	Success:	TRUE(1)/FALSE(0)
+ * 		Failure:	FAIL
+ *
+ * Programmer:	Quincey Koziol
+ *              Friday, June 11, 2004
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5FD_can_extend(const H5FD_t *file, H5FD_mem_t type, haddr_t addr, hsize_t size, hsize_t extra_requested)
+{
+    haddr_t end;                        /* End of block in file */
+    haddr_t eoa;                        /* End of address space in the file */
+    htri_t  ret_value = FALSE;          /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_can_extend, FAIL)
+
+    /* Retrieve the end of the address space */
+    if(HADDR_UNDEF == (eoa = H5FD_get_eoa(file, type)))
+	HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "driver get_eoa request failed")
+
+    /* Compute end of block */
+    end = addr + size;
+
+    /* Check if the block is exactly at the end of the file */
+    if(end == eoa)
+        HGOTO_DONE(TRUE)
+    else {
+        H5FD_free_t *curr;          /* Current free block being inspected */
+        H5FD_mem_t mapped_type;     /* Memory type, after mapping */
+
+        /* Map request type to free list */
+        if(H5FD_MEM_DEFAULT==file->cls->fl_map[type])
+            mapped_type = type;
+        else
+            mapped_type = file->cls->fl_map[type];
+
+        /* Check if block is inside the metadata or small data aggregator */
+        if(mapped_type!=H5FD_MEM_DRAW) {
+            /* Check for test block able to extend metadata aggregation block */
+            if((ret_value = H5FD_aggr_can_extend(file, &(file->meta_aggr), eoa, end)) < 0)
+                HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "can't determine if metadata aggregation block can be extended")
+            else if(ret_value > 0)
+                HGOTO_DONE(TRUE)
+        } /* end if */
+        else {
+            /* Check for test block able to extend metadata aggregation block */
+            if((ret_value = H5FD_aggr_can_extend(file, &(file->sdata_aggr), eoa, end)) < 0)
+                HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "can't determine if 'small data' aggregation block can be extended")
+            else if(ret_value > 0)
+                HGOTO_DONE(TRUE)
+        } /* end else */
+
+        /* Scan through the existing blocks for the mapped type to see if we can extend one */
+        if(mapped_type >= H5FD_MEM_DEFAULT) {
+            curr = file->fl[mapped_type];
+            while(curr != NULL) {
+                if(end == curr->addr) {
+                    if(extra_requested <= curr->size)
+                        HGOTO_DONE(TRUE)
+                    else
+                        HGOTO_DONE(FALSE)
+                } /* end if */
+
+                /* Advance to next node in list */
+                curr=curr->next;
+            } /* end while */
+        } /* end if */
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_can_extend() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_extend
+ *
+ * Purpose:	Extend a block in the file.
+ *
+ * Return:	Success:	Non-negative
+ * 		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Saturday, June 12, 2004
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FD_extend(H5FD_t *file, H5FD_mem_t type, haddr_t addr, hsize_t size, hsize_t extra_requested)
+{
+    haddr_t     eoa;                    /* End of address space in the file */
+    haddr_t     end;                    /* End of block in file */
+    hbool_t     update_eoma=FALSE;      /* Whether we need to update the eoma */
+    hbool_t     update_eosda=FALSE;     /* Whether we need to update the eosda */
+    hbool_t     at_end=FALSE;           /* Block is at end of file */
+    H5FD_mem_t  mapped_type;            /* Memory type, after mapping */
+    herr_t      ret_value=SUCCEED;      /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_extend, FAIL)
+#ifdef H5FD_ALLOC_DEBUG
+HDfprintf(stderr, "%s: type = %u, addr = %a, size = %Hu, extra_requested = %Hu\n", FUNC, (unsigned)type, addr, size, extra_requested);
+#endif /* H5FD_ALLOC_DEBUG */
+
+    /* Retrieve the end of the address space */
+    if(HADDR_UNDEF==(eoa=H5FD_get_eoa(file, type)))
+	HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "driver get_eoa request failed")
+
+    /* Map request type to free list */
+    if(H5FD_MEM_DEFAULT==file->cls->fl_map[type])
+        mapped_type = type;
+    else
+        mapped_type = file->cls->fl_map[type];
+
+    /* Compute end of block */
+    end = addr + size;
+
+    /* Check if the block is exactly at the end of the file */
+    if(end == eoa)
+        at_end = TRUE;
+    else {
+        /* (Check if block is inside the metadata or small data accumulator) */
+        if(mapped_type!=H5FD_MEM_DRAW) {
+            /* Check for test block able to extend metadata aggregation block */
+            if((ret_value = H5FD_aggr_can_extend(file, &(file->meta_aggr), eoa, end)) < 0)
+                HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "can't determine if metadata aggregation block can be extended")
+            else if(ret_value > 0)
+                update_eoma = TRUE;
+        } /* end if */
+        else {
+            /* Check for test block able to extend metadata aggregation block */
+            if((ret_value = H5FD_aggr_can_extend(file, &(file->sdata_aggr), eoa, end)) < 0)
+                HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "can't determine if metadata aggregation block can be extended")
+            else if(ret_value > 0)
+                update_eosda = TRUE;
+        } /* end else */
+    } /* end else */
+
+    /* Block is at end of file, we are extending the eoma or eosda */
+    if(update_eoma || update_eosda || at_end) {
+        /* Check for overflowing the file */
+        if(H5F_addr_overflow(eoa, extra_requested) || eoa + extra_requested > file->maxaddr)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, FAIL, "file allocation request failed")
+
+        /* Extend the file */
+        eoa += extra_requested;
+        if(file->cls->set_eoa(file, type, eoa) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, FAIL, "file allocation request failed")
+
+        /* Update the metadata and/or small data block */
+        HDassert(!(update_eoma && update_eosda));
+        if(update_eoma)
+            H5FD_aggr_shift(&(file->meta_aggr), extra_requested);
+        if(update_eosda)
+            H5FD_aggr_shift(&(file->sdata_aggr), extra_requested);
+    } /* end if */
+    /* If the block we are extending isn't at the end of the file, find a free block to extend into */
+    else {
+        H5FD_free_t *curr;          /* Current free block being inspected */
+        H5FD_free_t *prev;          /* Current free block being inspected */
+
+        /* Walk through free list, looking for block to merge with */
+        curr = file->fl[mapped_type];
+        prev = NULL;
+        while(curr!=NULL) {
+            /* Found block that ajoins end of block to extend */
+            if(end == curr->addr) {
+                /* Check if free space is large enough */
+                if(extra_requested <= curr->size) {
+                    /* Check for exact match */
+                    if(extra_requested == curr->size) {
+                        /* Unlink node from free list */
+                        if(prev == NULL)
+                            file->fl[mapped_type] = curr->next;
+                        else
+                            prev->next = curr->next;
+
+                        /* Free the memory for the used block */
+                        H5FL_FREE(H5FD_free_t, curr);
+                    } /* end if */
+                    else {
+                        curr->addr += extra_requested;
+                        curr->size -= extra_requested;
+                    } /* end else */
+
+                    /* Leave now */
+                    break;
+                } /* end if */
+                else
+                    HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, FAIL, "can't extend block")
+            } /* end if */
+
+            /* Advance to next node in list */
+            prev = curr;
+            curr = curr->next;
+        } /* end while */
+
+        /* Couldn't find block to extend */
+        if(curr == NULL)
+            HGOTO_ERROR(H5E_VFL, H5E_NOSPACE, FAIL, "can't extend block")
+    } /* end else */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_extend() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_get_freespace
+ *
+ * Purpose:     Retrieve the amount of free space in a file.
+ *
+ * Return:      Success:        Amount of free space in file
+ *              Failure:        Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Monday, October  6, 2003
+ *
+ * Note:
+ *              Raymond Lu
+ *              5 January 2007
+ *              Due to the complexity EOA for Multi driver, this function
+ *              is made failed for now.
+ * 
+ *-------------------------------------------------------------------------
+ */
+hssize_t
+H5FD_get_freespace(const H5FD_t *file)
+{
+    H5FD_free_t *free_node;     /* Pointer to node on free list */
+    H5FD_mem_t type;            /* Type of memory */
+    haddr_t ma_addr = HADDR_UNDEF;    /* Base "metadata aggregator" address */
+    hsize_t ma_size = 0;        /* Size of "metadata aggregator" */
+    haddr_t sda_addr = HADDR_UNDEF;    /* Base "small data aggregator" address */
+    hsize_t sda_size = 0;       /* Size of "small data aggregator" */
+    haddr_t eoa = 0;            /* End of allocated space in the file */
+    hssize_t ret_value = 0;     /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_get_freespace, FAIL)
+
+    /* check args */
+    HDassert(file);
+    HDassert(file->cls);
+
+    /* Multi driver doesn't support this function because of the complexity.
+     * It doesn't have eoa for the whole file. */
+    if(file->driver_id == H5FD_MULTI)
+        HGOTO_ERROR(H5E_VFL, H5E_CANTGET, FAIL, "Multi driver doesn't support this function")
+    
+    /* Retrieve the 'eoa' for the file */
+    eoa = file->cls->get_eoa(file, H5FD_MEM_DEFAULT);
+
+    /* Retrieve metadata aggregator info, if available */
+    H5FD_aggr_query(file, &(file->meta_aggr), &ma_addr, &ma_size);
+
+    /* Retrieve 'small data' aggregator info, if available */
+    H5FD_aggr_query(file, &(file->sdata_aggr), &sda_addr, &sda_size);
+
+    /* Iterate over all the types of memory, to retrieve amount of free space for each */
+    for(type = H5FD_MEM_DEFAULT; type < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t,type)) {
+        /* Iterate through the free list, accumulating the amount of free space for this type */
+        free_node = file->fl[type];
+        while(free_node) {
+            /* Check for current node adjoining the metadata & small data aggregators */
+            if(H5F_addr_eq(free_node->addr + free_node->size, ma_addr)) {
+                ma_addr -= free_node->size;
+                ma_size += free_node->size;
+            } else if(H5F_addr_eq(free_node->addr + free_node->size, sda_addr)) {
+                sda_addr -= free_node->size;
+                sda_size += free_node->size;
+            } else if(H5F_addr_eq(ma_addr + ma_size, free_node->addr))
+                ma_size += free_node->size;
+            else if(H5F_addr_eq(sda_addr + sda_size, free_node->addr))
+                sda_size += free_node->size;
+            else
+                ret_value += (hssize_t)free_node->size;
+            free_node = free_node->next;
+        } /* end while */
+    } /* end for */
+
+    /* Check for aggregating metadata allocations */
+    if(ma_size > 0) {
+        /* Add in the reserved space for metadata to the available free space */
+        /* (if it's not at the tail of the file) */
+        if(H5F_addr_ne(ma_addr + ma_size, eoa))
+            ret_value += ma_size;
+    } /* end if */
+
+    /* Check for aggregating small data allocations */
+    if(sda_size > 0) {
+        /* Add in the reserved space for metadata to the available free space */
+        /* (if it's not at the tail of the file) */
+        if(H5F_addr_ne(sda_addr + sda_size, eoa))
+            ret_value += sda_size;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_get_freespace() */
+