[svn-r12125] Purpose:

    Code checkpoint

Description:
    Update fractal heap code to insert & read heaps up to 64MB in size
(with my current configuration paramaters) and add initial support for
iteratively walking down nested indirect blocks.

Platforms tested:
    FreeBSD 4.11 (sleipnir)
    Linux 2.4 (chicago)
    Solaris 9 (shanti)
    Linux 2.4 (mir) w/64-bit

7 files changed, 597 insertions, 340 deletions

diff --git a/src/H5HF.c b/src/H5HF.c
index ac5990b..feb88be 100644
--- a/src/H5HF.c
+++ b/src/H5HF.c
@@ -99,6 +99,7 @@ herr_t
 H5HF_create(H5F_t *f, hid_t dxpl_id, H5HF_create_t *cparam, haddr_t *addr_p)
 {
     H5HF_t *fh = NULL;                  /* The new fractal heap header information */
+    H5HF_shared_t *shared = NULL;       /* Shared fractal heap information */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5HF_create, FAIL)
@@ -119,12 +120,16 @@ H5HF_create(H5F_t *f, hid_t dxpl_id, H5HF_create_t *cparam, haddr_t *addr_p)
     /* Reset the metadata cache info for the heap header */
     HDmemset(&fh->cache_info, 0, sizeof(H5AC_info_t));
 
+    /* Allocate & basic initialization for the shared info struct */
+    if(NULL == (shared = H5HF_shared_alloc(f)))
+	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate space for shared heap info")
+
     /* Allocate space for the header on disk */
-    if(HADDR_UNDEF == (*addr_p = H5MF_alloc(f, H5FD_MEM_FHEAP_HDR, dxpl_id, (hsize_t)H5HF_HEADER_SIZE(f))))
+    if(HADDR_UNDEF == (*addr_p = H5MF_alloc(f, H5FD_MEM_FHEAP_HDR, dxpl_id, (hsize_t)H5HF_HEADER_SIZE(shared))))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap header")
 
     /* Initialize shared fractal heap info */
-    if(H5HF_shared_create(f, fh, *addr_p, cparam) < 0)
+    if(H5HF_shared_init(shared, fh, *addr_p, cparam) < 0)
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't create shared fractal heap info")
 
     /* Cache the new fractal heap header */
diff --git a/src/H5HFcache.c b/src/H5HFcache.c
index fbeecc8..1fd3b51 100644
--- a/src/H5HFcache.c
+++ b/src/H5HFcache.c
@@ -283,7 +283,7 @@ H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *ud
     shared->heap_addr = addr;
 
     /* Compute the size of the fractal heap header on disk */
-    size = H5HF_HEADER_SIZE(f);
+    size = H5HF_HEADER_SIZE(shared);
 
     /* Allocate temporary buffer */
     if((buf = H5FL_BLK_MALLOC(header_block, size)) == NULL)
@@ -399,7 +399,7 @@ H5HF_cache_hdr_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5H
         HDassert(shared->dirty);
 
         /* Compute the size of the heap header on disk */
-        size = H5HF_HEADER_SIZE(f);
+        size = H5HF_HEADER_SIZE(shared);
 
         /* Allocate temporary buffer */
         if((buf = H5FL_BLK_MALLOC(header_block, size)) == NULL)
@@ -554,16 +554,23 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_cache_hdr_size(const H5F_t *f, const H5HF_t UNUSED *fh, size_t *size_ptr)
+H5HF_cache_hdr_size(const H5F_t *f, const H5HF_t *fh, size_t *size_ptr)
 {
+    H5HF_shared_t *shared;              /* Shared fractal heap information */
+
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_cache_hdr_size)
 
     /* check arguments */
     HDassert(f);
+    HDassert(fh);
     HDassert(size_ptr);
 
+    /* Get the pointer to the shared heap info */
+    shared = H5RC_GET_OBJ(fh->shared);
+    HDassert(shared);
+
     /* Set size value */
-    *size_ptr = H5HF_HEADER_SIZE(f);
+    *size_ptr = H5HF_HEADER_SIZE(shared);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5HF_cache_hdr_size() */
@@ -994,14 +1001,10 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_nrows
 
     /* Set block's internal information */
     iblock->nrows = *nrows;
-    if(iblock->nrows > shared->man_dtable.max_direct_rows) {
-        iblock->ndir_rows = shared->man_dtable.max_direct_rows;
-        iblock->nindir_rows = iblock->nrows - iblock->ndir_rows;
-    } /* end if */
-    else {
-        iblock->ndir_rows = iblock->nrows;
-        iblock->nindir_rows = 0;
-    } /* end else */
+    if(!iblock->parent)
+        iblock->max_rows = shared->man_dtable.max_root_rows;
+    else
+        iblock->max_rows = *nrows;
 
     /* Compute size of indirect block */
     iblock->size = H5HF_MAN_INDIRECT_SIZE(shared, iblock);
@@ -1037,7 +1040,7 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_nrows
     if(metadata_chksum != 0)
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "incorrect metadata checksum for fractal heap direct block")
 
-    /* Address of heap that owns this block (skip) */
+    /* Address of heap that owns this block */
     H5F_addr_decode(f, &p, &heap_addr);
     if(H5F_addr_ne(heap_addr, shared->heap_addr))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "incorrect heap header address for direct block")
@@ -1045,47 +1048,28 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_nrows
     /* Offset of heap within the heap's address space */
     UINT64DECODE_VAR(p, iblock->block_off, shared->heap_off_size);
 
+    /* Offset of next entry to allocate within this block */
+    UINT32DECODE(p, iblock->next_entry);
+
+    /* Compute next block column, row & size */
+    iblock->next_col = iblock->next_entry % shared->man_dtable.cparam.width;
+    iblock->next_row = iblock->next_entry / shared->man_dtable.cparam.width;
+    iblock->next_size = shared->man_dtable.row_block_size[iblock->next_row];
+
     /* Allocate & decode indirect block entry tables */
-    HDassert(iblock->ndir_rows > 0);
-    if(NULL == (iblock->dblock_ents = H5FL_SEQ_MALLOC(H5HF_indirect_dblock_ent_t, (iblock->ndir_rows * shared->man_dtable.cparam.width))))
+    HDassert(iblock->nrows > 0);
+    if(NULL == (iblock->ents = H5FL_SEQ_MALLOC(H5HF_indirect_ent_t, (iblock->nrows * shared->man_dtable.cparam.width))))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for direct entries")
-    iblock->dir_full = TRUE;
-    for(u = 0; u < (iblock->ndir_rows * shared->man_dtable.cparam.width); u++) {
-        H5F_addr_decode(f, &p, &(iblock->dblock_ents[u].addr));
-        UINT32DECODE_VAR(p, iblock->dblock_ents[u].free_space, shared->man_dtable.max_dir_blk_off_size);
-
-        /* Check for direct block being undefined and use that for the next one to allocate from this indirect block */
-        if(iblock->dir_full) {
-            if(!H5F_addr_defined(iblock->dblock_ents[u].addr)) {
-                iblock->next_dir_col = u % shared->man_dtable.cparam.width;
-                iblock->next_dir_row = u / shared->man_dtable.cparam.width;
-                iblock->next_dir_entry = u;
-                if(iblock->next_dir_row == 0)
-                    iblock->next_dir_size = shared->man_dtable.cparam.start_block_size;
-                else
-                    iblock->next_dir_size = shared->man_dtable.cparam.start_block_size * (1 << (iblock->next_dir_row - 1));
-                if(iblock->block_off == 0)
-                    iblock->max_direct_rows = shared->man_dtable.max_direct_rows;
-                else
-                    HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, NULL, "computing max direct rows for non-root indirect block not supported yet")
-
-                /* Set the flag to indicate the direct blocks aren't full */
-                iblock->dir_full = FALSE;
-            } /* end if */
-        } /* end if */
+    for(u = 0; u < (iblock->nrows * shared->man_dtable.cparam.width); u++) {
+        /* Decode block address */
+        H5F_addr_decode(f, &p, &(iblock->ents[u].addr));
+
+        /* Decode direct & indirect blocks differently */
+        if(u < (shared->man_dtable.max_direct_rows * shared->man_dtable.cparam.width))
+            UINT32DECODE_VAR(p, iblock->ents[u].free_space, shared->man_dtable.max_dir_blk_off_size)
+        else
+            UINT64DECODE_VAR(p, iblock->ents[u].free_space, shared->heap_off_size)
     } /* end for */
-    if(iblock->nindir_rows > 0) {
-        if(NULL == (iblock->iblock_ents = H5FL_SEQ_MALLOC(H5HF_indirect_iblock_ent_t, (iblock->nindir_rows * shared->man_dtable.cparam.width))))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for indirect entries")
-
-        /* Decode indirect block-specific fields */
-        for(u = 0; u < (iblock->nindir_rows * shared->man_dtable.cparam.width); u++) {
-            H5F_addr_decode(f, &p, &(iblock->iblock_ents[u].addr));
-            UINT64DECODE_VAR(p, iblock->iblock_ents[u].free_space, shared->heap_off_size);
-        } /* end for */
-    } /* end if */
-    else
-        iblock->iblock_ents = NULL;
 
     /* Sanity check */
     HDassert((size_t)(p - buf) == iblock->size);
@@ -1150,8 +1134,6 @@ HDfprintf(stderr, "%s: Flushing indirect block\n", FUNC);
 /* XXX: Use free list factories? */
 #ifdef QAK
 HDfprintf(stderr, "%s: iblock->nrows = %u\n", FUNC, iblock->nrows);
-HDfprintf(stderr, "%s: iblock->ndir_rows = %u\n", FUNC, iblock->ndir_rows);
-HDfprintf(stderr, "%s: iblock->nindir_rows = %u\n", FUNC, iblock->nindir_rows);
 HDfprintf(stderr, "%s: iblock->size = %Zu\n", FUNC, iblock->size);
 HDfprintf(stderr, "%s: iblock->block_off = %Hu\n", FUNC, iblock->block_off);
 HDfprintf(stderr, "%s: shared->man_dtable.cparam.width = %u\n", FUNC, shared->man_dtable.cparam.width);
@@ -1182,21 +1164,21 @@ HDfprintf(stderr, "%s: shared->man_dtable.cparam.width = %u\n", FUNC, shared->ma
 
         /* Offset of block in heap */
         UINT64ENCODE_VAR(p, iblock->block_off, shared->heap_off_size);
-/* XXX: Fix this when we start writing recursive indirect blocks */
-if(iblock->block_off != 0)
-    HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, FAIL, "fix computing max direct rows for non-root indirect block for loading")
+
+        /* Next block entry to allocate from */
+        UINT32ENCODE(p, iblock->next_entry);
 
         /* Encode indirect block-specific fields */
-        HDassert(iblock->ndir_rows > 0);
-        for(u = 0; u < (iblock->ndir_rows * shared->man_dtable.cparam.width); u++) {
-            H5F_addr_encode(f, &p, iblock->dblock_ents[u].addr);
-            UINT32ENCODE_VAR(p, iblock->dblock_ents[u].free_space, shared->man_dtable.max_dir_blk_off_size);
+        for(u = 0; u < (iblock->nrows * shared->man_dtable.cparam.width); u++) {
+            /* Encode block address */
+            H5F_addr_encode(f, &p, iblock->ents[u].addr);
+
+            /* Encode direct & indirect blocks differently */
+            if(u < (shared->man_dtable.max_direct_rows * shared->man_dtable.cparam.width))
+                UINT32ENCODE_VAR(p, iblock->ents[u].free_space, shared->man_dtable.max_dir_blk_off_size)
+            else
+                UINT64ENCODE_VAR(p, iblock->ents[u].free_space, shared->heap_off_size)
         } /* end for */
-        if(iblock->nindir_rows > 0)
-            for(u = 0; u < (iblock->nindir_rows * shared->man_dtable.cparam.width); u++) {
-                H5F_addr_encode(f, &p, iblock->iblock_ents[u].addr);
-                UINT64ENCODE_VAR(p, iblock->iblock_ents[u].free_space, shared->heap_off_size);
-            } /* end for */
 
         /* Sanity check */
         HDassert((size_t)(p - buf) == iblock->size);
diff --git a/src/H5HFdbg.c b/src/H5HFdbg.c
index 5dddac7..43a6064 100644
--- a/src/H5HFdbg.c
+++ b/src/H5HFdbg.c
@@ -133,7 +133,7 @@ H5HF_dtable_debug(H5HF_dtable_t *dtable, FILE *stream, int indent, int fwidth)
     /* Computed values */
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Max. # of rows in root indirect block:",
-	      dtable->max_root_indirect_rows);
+	      dtable->max_root_rows);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Max. # of direct rows in any indirect block:",
 	      dtable->max_direct_rows);
@@ -476,35 +476,28 @@ H5HF_iblock_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream,
 	      "Size of indirect block:",
 	      iblock->size);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Total # of rows:",
+	      "Current # of rows:",
 	      iblock->nrows);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "# of direct rows:",
-	      iblock->ndir_rows);
-    HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "# of indirect rows:",
-	      iblock->nindir_rows);
-    HDfprintf(stream, "%*s%-*s %s\n", indent, "", fwidth,
-	      "Direct blocks full:",
-	      (iblock->dir_full ? "TRUE" : "FALSE"));
+	      "Max. # of rows:",
+	      iblock->max_rows);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Max direct block rows:",
-	      iblock->max_direct_rows);
+	      shared->man_dtable.max_direct_rows);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Next direct block column:",
-	      iblock->next_dir_col);
+	      "Next block column:",
+	      iblock->next_col);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Next direct block row:",
-	      iblock->next_dir_row);
-    HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Next direct block size:",
-	      iblock->next_dir_size);
+	      "Next block row:",
+	      iblock->next_row);
+    HDfprintf(stream, "%*s%-*s %Hu\n", indent, "", fwidth,
+	      "Next block size:",
+	      iblock->next_size);
 
     /* Print the entry tables */
-    dblock_size = shared->man_dtable.cparam.start_block_size;
     HDfprintf(stream, "%*sDirect Block Entries (address, free space):\n", indent, "");
-    for(u = 0; u < iblock->ndir_rows; u++) {
-        sprintf(temp_str, "Row #%u: (block size: %lu)", (unsigned)u, (unsigned long)dblock_size);
+    for(u = 0; u < shared->man_dtable.max_direct_rows && u < iblock->nrows; u++) {
+        sprintf(temp_str, "Row #%u: (block size: %lu)", (unsigned)u, (unsigned long)shared->man_dtable.row_block_size[u]);
         HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(0, fwidth - 3),
                 temp_str);
         for(v = 0; v < shared->man_dtable.cparam.width; v++) {
@@ -513,14 +506,14 @@ H5HF_iblock_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream,
             sprintf(temp_str, "Col #%u:", (unsigned)v);
             HDfprintf(stream, "%*s%-*s %8a, %8Zu\n", indent + 6, "", MAX(0, fwidth - 6),
                     temp_str,
-                    iblock->dblock_ents[off].addr,
-                    iblock->dblock_ents[off].free_space);
+                    iblock->ents[off].addr,
+                    iblock->ents[off].free_space);
         } /* end for */
         dblock_size *= 2;
     } /* end for */
     HDfprintf(stream, "%*sIndirect Block Entries:\n", indent, "");
-    if(iblock->nindir_rows > 0) {
-        for(u = 0; u < iblock->nindir_rows; u++) {
+    if(iblock->nrows > shared->man_dtable.max_direct_rows) {
+        for(u = shared->man_dtable.max_direct_rows; u < iblock->nrows; u++) {
             sprintf(temp_str, "Row #%u:", (unsigned)u);
             HDfprintf(stream, "%*s%-*s\n", indent + 3, "", MAX(0, fwidth - 3),
                     temp_str);
@@ -528,9 +521,10 @@ H5HF_iblock_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream,
                 size_t off = (u * shared->man_dtable.cparam.width) + v;
 
                 sprintf(temp_str, "Col #%u:", (unsigned)v);
-                HDfprintf(stream, "%*s%-*s %8a\n", indent + 6, "", MAX(0, fwidth - 6),
+                HDfprintf(stream, "%*s%-*s %8a, %8Zu\n", indent + 6, "", MAX(0, fwidth - 6),
                         temp_str,
-                        iblock->iblock_ents[off].addr);
+                        iblock->ents[off].addr,
+                        iblock->ents[off].free_space);
             } /* end for */
         } /* end for */
     } /* end if */
diff --git a/src/H5HFflist.c b/src/H5HFflist.c
index 361bb37..97e30e9 100644
--- a/src/H5HFflist.c
+++ b/src/H5HFflist.c
@@ -44,6 +44,13 @@
 /* Local Typedefs */
 /******************/
 
+/* Structure for storing single free list section */
+typedef struct H5HF_flist_single_t {
+    void *node;                 /* Pointer to section's node */
+    size_t *size_key;           /* Pointer to size key for section */
+    haddr_t *addr_key;          /* Pointer to address key for section */
+} H5HF_flist_single_t;
+
 /* Free list node for free list sections of the same size */
 typedef struct H5HF_flist_node_t {
     size_t sec_size;            /* Size of all sections on list */
@@ -58,6 +65,8 @@ typedef struct H5HF_flist_node_t {
 /* Main free list info */
 struct H5HF_freelist_t {
     hsize_t tot_space;          /* Total amount of space in free list         */
+    size_t sec_count;           /* # of sections on free list                 */
+    H5HF_flist_single_t single; /* Section information when free list has only one free section */
     unsigned nbins;             /* Number of bins                             */
     H5SL_operator_t node_free_op;       /* Callback for freeing nodes when free list is destroyed */
     H5SL_t **bins;              /* Pointer to array of lists of free nodes    */
@@ -128,12 +137,13 @@ H5HF_flist_create(size_t max_block_size, H5SL_operator_t node_free_op)
 
     /* Set free list parameters */
     flist->tot_space = 0;
+    flist->sec_count = 0;
+    flist->single.node = NULL;
+    flist->single.size_key = NULL;
+    flist->single.addr_key = NULL;
     flist->nbins = H5V_log2_of2(max_block_size);
     flist->node_free_op = node_free_op;
-
-    /* Allocate the bins for free space sizes */
-    if(NULL == (flist->bins = H5FL_SEQ_CALLOC(H5SL_ptr_t, flist->nbins)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for free list bins")
+    flist->bins = NULL;
 
     /* Set return value */
     ret_value = flist;
@@ -144,27 +154,28 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_flist_add
+ * Function:	H5HF_flist_add_bin_node
  *
  * Purpose:	Add a section of free space in a direct block to the free list
+ *              bins
  *
  * Return:	Success:	non-negative
  *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
- *              Tuesday, March  7, 2006
+ *              Monday, March 20, 2006
  *
  *-------------------------------------------------------------------------
  */
-herr_t
-H5HF_flist_add(H5HF_freelist_t *flist, void *node, size_t *size_key, haddr_t *addr_key)
+static herr_t
+H5HF_flist_add_bin_node(H5HF_freelist_t *flist, void *node, size_t *size_key, haddr_t *addr_key)
 {
     H5HF_flist_node_t *flist_node = NULL;   /* Pointer to free list node of the correct size */
     unsigned bin;                       /* Bin to put the free space section in */
     herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5HF_flist_add)
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_flist_add_bin_node)
 #ifdef QAK
 HDfprintf(stderr, "%s: *size_key = %Zu, *addr_key = %a\n", FUNC, *size_key, *addr_key);
 #endif /* QAK */
@@ -208,13 +219,83 @@ HDfprintf(stderr, "%s: *size_key = %Zu, *addr_key = %a\n", FUNC, *size_key, *add
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
+} /* H5HF_flist_add_bin_node() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF_flist_add
+ *
+ * Purpose:	Add a section of free space in a direct block to the free list
+ *
+ * Return:	Success:	non-negative
+ *
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Tuesday, March  7, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5HF_flist_add(H5HF_freelist_t *flist, void *node, size_t *size_key, haddr_t *addr_key)
+{
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_flist_add)
+#ifdef QAK
+HDfprintf(stderr, "%s: *size_key = %Zu, *addr_key = %a\n", FUNC, *size_key, *addr_key);
+#endif /* QAK */
+
+    /* Check arguments. */
+    HDassert(flist);
+    HDassert(node);
+    HDassert(size_key);
+    HDassert(addr_key);
+
+    /* Check for special cases of # of sections on free list */
+    if(flist->sec_count == 0) {
+        HDassert(flist->single.node == NULL);
+
+        /* Capture single section's information */
+        flist->single.node = node;
+        flist->single.size_key = size_key;
+        flist->single.addr_key = addr_key;
+    } /* end if */
+    else {
+        /* Have a single section, put it into the bins */
+         if(flist->sec_count == 1) {
+            HDassert(flist->single.node);
+
+            /* Check if we should allocate the bins */
+            if(flist->bins == NULL)
+                /* Allocate the bins for free space sizes */
+                if(NULL == (flist->bins = H5FL_SEQ_CALLOC(H5SL_ptr_t, flist->nbins)))
+                    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for free list bins")
+
+            /* Insert the current single section into the bins */
+            if(H5HF_flist_add_bin_node(flist, flist->single.node, flist->single.size_key, flist->single.addr_key) < 0)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTINSERT, FAIL, "can't insert free list node into skip list")
+            flist->single.node = NULL;
+        } /* end if */
+        HDassert(flist->single.node == NULL);
+
+        /* Put new section into bins */
+        if(H5HF_flist_add_bin_node(flist, node, size_key, addr_key) < 0)
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTINSERT, FAIL, "can't insert free list node into skip list")
+    } /* end else */
+
+    /* Increment # of sections on free list */
+    flist->sec_count++;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* H5HF_flist_add() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_flist_find
+ * Function:	H5HF_flist_find_bin_node
  *
- * Purpose:	Locate a section of free space (in existing free list) that
+ * Purpose:	Locate a section of free space (in existing free list bins) that
  *              is large enough to fulfill request.
  *
  * Return:	Success:	non-negative
@@ -222,18 +303,18 @@ done:
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
- *              Tuesday, March  7, 2006
+ *              Monday, March 20, 2006
  *
  *-------------------------------------------------------------------------
  */
-htri_t
-H5HF_flist_find(H5HF_freelist_t *flist, size_t request, void **node)
+static htri_t
+H5HF_flist_find_bin_node(H5HF_freelist_t *flist, size_t request, void **node)
 {
     H5HF_flist_node_t *flist_node;      /* Free list size node */
     unsigned bin;                       /* Bin to put the free space section in */
-    herr_t ret_value = FALSE;           /* Return value */
+    htri_t ret_value = FALSE;           /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5HF_flist_find)
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_flist_find_bin_node)
 
     /* Check arguments. */
     HDassert(flist);
@@ -289,6 +370,64 @@ HDfprintf(stderr, "%s: bin = %u\n", FUNC, bin);
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
+} /* H5HF_flist_find_bin_node() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF_flist_find
+ *
+ * Purpose:	Locate a section of free space (in existing free list) that
+ *              is large enough to fulfill request.
+ *
+ * Return:	Success:	non-negative
+ *
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Tuesday, March  7, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5HF_flist_find(H5HF_freelist_t *flist, size_t request, void **node)
+{
+    htri_t ret_value = FALSE;           /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_flist_find)
+
+    /* Check arguments. */
+    HDassert(flist);
+    HDassert(request > 0);
+    HDassert(node);
+
+    /* Check for any sections on free list */
+    if(flist->sec_count > 0) {
+        /* Check for single section */
+        if(flist->sec_count == 1) {
+            HDassert(flist->single.node);
+
+            /* See if single section is large enough */
+            if(*(flist->single.size_key) >= request) {
+                *node = flist->single.node;
+                flist->single.node = NULL;
+                ret_value = TRUE;
+            } /* end if */
+        } /* end if */
+        else {
+            HDassert(flist->single.node == NULL);
+
+            /* Look for node in bins */
+            if((ret_value = H5HF_flist_find_bin_node(flist, request, node)) < 0)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "can't remove section from bins")
+        } /* end else */
+
+        /* Decrement # of sections on free list */
+        flist->sec_count--;
+/* XXX: Should check for only one section in bins & convert to single section */
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* H5HF_flist_find() */
 
 
@@ -349,15 +488,25 @@ H5HF_flist_free(H5HF_freelist_t *flist)
     /* Check arguments. */
     HDassert(flist);
 
-    /* Clear out lists of nodes */
-    for(u = 0; u < flist->nbins; u++)
-        if(flist->bins[u]) {
-            H5SL_destroy(flist->bins[u], H5HF_flist_node_free_cb, (void *)flist->node_free_op);
-            flist->bins[u] = NULL;
-        } /* end if */
+    /* Check for single section to free */
+    if(flist->sec_count == 1) {
+        HDassert(flist->single.node != NULL);
+        flist->node_free_op(flist->single.node, flist->single.addr_key, NULL);
+        flist->single.node = NULL;
+    } /* end if */
+    HDassert(flist->single.node == NULL);
 
     /* Release bins for skip lists */
-    H5FL_SEQ_FREE(H5SL_ptr_t, flist->bins);
+    if(flist->bins) {
+        /* Clear out lists of nodes */
+        for(u = 0; u < flist->nbins; u++)
+            if(flist->bins[u]) {
+                H5SL_destroy(flist->bins[u], H5HF_flist_node_free_cb, (void *)flist->node_free_op);
+                flist->bins[u] = NULL;
+            } /* end if */
+
+        H5FL_SEQ_FREE(H5SL_ptr_t, flist->bins);
+    } /* end if */
 
     /* Free fractal heap free list info */
     H5FL_FREE(H5HF_freelist_t, flist);
diff --git a/src/H5HFint.c b/src/H5HFint.c
index bbae6a2..e25ad64 100644
--- a/src/H5HFint.c
+++ b/src/H5HFint.c
@@ -98,7 +98,7 @@ static H5HF_indirect_t * H5HF_man_iblock_place_dblock(H5RC_t *fh_shared, hid_t d
     size_t min_dblock_size, haddr_t *addr_p, size_t *entry_p,
     size_t *dblock_size);
 static herr_t H5HF_man_iblock_create(H5RC_t *fh_shared, hid_t dxpl_id,
-    hsize_t block_off, unsigned nrows, unsigned max_dir_rows, haddr_t *addr_p);
+    hsize_t block_off, unsigned nrows, unsigned max_rows, haddr_t *addr_p);
 
 /*********************/
 /* Package Variables */
@@ -119,11 +119,8 @@ H5FL_DEFINE(H5HF_section_free_node_t);
 /* Declare a free list to manage the H5HF_indirect_t struct */
 H5FL_DEFINE(H5HF_indirect_t);
 
-/* Declare a free list to manage the H5HF_indirect_dblock_ent_t sequence information */
-H5FL_SEQ_DEFINE(H5HF_indirect_dblock_ent_t);
-
-/* Declare a free list to manage the H5HF_indirect_iblock_ent_t sequence information */
-H5FL_SEQ_DEFINE(H5HF_indirect_iblock_ent_t);
+/* Declare a free list to manage the H5HF_indirect_ent_t sequence information */
+H5FL_SEQ_DEFINE(H5HF_indirect_ent_t);
 
 
 /*****************************/
@@ -171,18 +168,18 @@ H5HF_dtable_init(const H5HF_shared_t *shared, H5HF_dtable_t *dtable)
     /* Compute/cache some values */
     dtable->first_row_bits = H5V_log2_of2(dtable->cparam.start_block_size) +
             H5V_log2_of2(dtable->cparam.width);
-    dtable->max_root_indirect_rows = (dtable->cparam.max_index - dtable->first_row_bits) + 1;
+    dtable->max_root_rows = (dtable->cparam.max_index - dtable->first_row_bits) + 1;
     dtable->max_direct_rows = (H5V_log2_of2(dtable->cparam.max_direct_size) -
             H5V_log2_of2(dtable->cparam.start_block_size)) + 2;
     dtable->num_id_first_row = dtable->cparam.start_block_size * dtable->cparam.width;
     dtable->max_dir_blk_off_size = H5HF_SIZEOF_OFFSET_LEN(dtable->cparam.max_direct_size);
 
     /* Build table of block sizes for each row */
-    if(NULL == (dtable->row_block_size = H5MM_malloc(dtable->max_root_indirect_rows * sizeof(hsize_t))))
+    if(NULL == (dtable->row_block_size = H5MM_malloc(dtable->max_root_rows * sizeof(hsize_t))))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't create doubling table block size table")
     tmp_block_size = dtable->cparam.start_block_size;
     dtable->row_block_size[0] = dtable->cparam.start_block_size;
-    for(u = 1; u < dtable->max_root_indirect_rows; u++) {
+    for(u = 1; u < dtable->max_root_rows; u++) {
         dtable->row_block_size[u] = tmp_block_size;
         tmp_block_size *= 2;
     } /* end for */
@@ -266,6 +263,8 @@ H5HF_shared_alloc(H5F_t *f)
 
     /* Set the internal parameters for the heap */
     shared->f = f;
+    shared->sizeof_size = H5F_SIZEOF_SIZE(f);
+    shared->sizeof_addr = H5F_SIZEOF_ADDR(f);
 
     /* Set the return value */
     ret_value = shared;
@@ -338,17 +337,16 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5HF_shared_create(H5F_t *f, H5HF_t *fh, haddr_t fh_addr, H5HF_create_t *cparam)
+H5HF_shared_init(H5HF_shared_t *shared, H5HF_t *fh, haddr_t fh_addr, H5HF_create_t *cparam)
 {
-    H5HF_shared_t *shared = NULL;       /* Shared fractal heap information */
     herr_t ret_value = SUCCEED;           /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5HF_shared_create)
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_shared_init)
 
     /*
      * Check arguments.
      */
-    HDassert(f);
+    HDassert(shared);
     HDassert(fh);
     HDassert(cparam);
 
@@ -363,14 +361,10 @@ H5HF_shared_create(H5F_t *f, H5HF_t *fh, haddr_t fh_addr, H5HF_create_t *cparam)
 	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "max. direct block size not power of two")
     if(cparam->managed.max_direct_size < cparam->standalone_size)
 	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "max. direct block size not large enough to hold all managed blocks")
-    if(cparam->managed.max_index > (8 * H5F_SIZEOF_SIZE(f)) || cparam->managed.max_index == 0)
+    if(cparam->managed.max_index > (8 * shared->sizeof_size) || cparam->managed.max_index == 0)
 	HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "max. direct block size not power of two")
 #endif /* NDEBUG */
 
-    /* Allocate & basic initialization for the shared info struct */
-    if(NULL == (shared = H5HF_shared_alloc(f)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate space for shared heap info")
-
     /* Set the creation parameters for the heap */
     shared->heap_addr = fh_addr;
     shared->addrmap = cparam->addrmap;
@@ -394,7 +388,7 @@ done:
             H5HF_shared_free(shared);
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_shared_create() */
+} /* end H5HF_shared_init() */
 
 
 /*-------------------------------------------------------------------------
@@ -451,8 +445,9 @@ static herr_t
 H5HF_man_iblock_inc_loc(H5HF_indirect_t *iblock)
 {
     H5HF_shared_t *shared;              /* Pointer to shared heap info */
+    herr_t ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_man_iblock_inc_loc)
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_man_iblock_inc_loc)
 
     /*
      * Check arguments.
@@ -463,33 +458,44 @@ H5HF_man_iblock_inc_loc(H5HF_indirect_t *iblock)
     shared = H5RC_GET_OBJ(iblock->shared);
     HDassert(shared);
 
+    /* Increment block entry */
+    iblock->next_entry++;
+
     /* Increment column */
-    iblock->next_dir_col++;
+    iblock->next_col++;
 
     /* Check for walking off end of column */
-    if(iblock->next_dir_col == shared->man_dtable.cparam.width) {
+    if(iblock->next_col == shared->man_dtable.cparam.width) {
         /* Reset column */
-        iblock->next_dir_col = 0;
+        iblock->next_col = 0;
 
-        /* Increment row & direct block size */
-        iblock->next_dir_row++;
-        iblock->next_dir_size *= 2;
+        /* Increment row & block size */
+        iblock->next_row++;
+        iblock->next_size *= 2;
 
-        /* Check for filling up all direct block entries in indirect block */
-        if(iblock->next_dir_row == iblock->max_direct_rows)
-            iblock->dir_full = TRUE;
+        /* Check for filling up indirect block */
+        if(iblock->next_row == iblock->max_rows) {
+            /* Check for "full" heap */
+            if(iblock->parent == NULL)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTINC, FAIL, "can't advance fractal heap block location")
+
+            /* Increment location for parent indirect block */
+            iblock = H5RC_GET_OBJ(iblock->parent);
+            if(H5HF_man_iblock_inc_loc(iblock) < 0)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTINC, FAIL, "can't advance fractal heap block location")
+        } /* end if */
     } /* end if */
 
 #ifdef QAK
-HDfprintf(stderr, "%s: iblock->next_dir_row = %u\n", "H5HF_man_iblock_inc_loc", iblock->next_dir_row);
-HDfprintf(stderr, "%s: iblock->next_dir_col = %u\n", "H5HF_man_iblock_inc_loc", iblock->next_dir_col);
-HDfprintf(stderr, "%s: iblock->next_dir_size = %Zu\n", "H5HF_man_iblock_inc_loc", iblock->next_dir_size);
-HDfprintf(stderr, "%s: iblock->dir_full = %u\n", "H5HF_man_iblock_inc_loc", (unsigned)iblock->dir_full);
+HDfprintf(stderr, "%s: iblock->next_row = %u\n", FUNC, iblock->next_row);
+HDfprintf(stderr, "%s: iblock->next_col = %u\n", FUNC, iblock->next_col);
+HDfprintf(stderr, "%s: iblock->next_size = %Zu\n", FUNC, iblock->next_size);
 #endif /* QAK */
     /* Mark heap header as modified */
     shared->dirty = TRUE;
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5HF_man_iblock_inc_loc() */
 
 
@@ -851,7 +857,7 @@ HDfprintf(stderr, "%s: amt = %Zd\n", "H5HF_man_dblock_adj_free", amt);
 #ifdef QAK
 HDfprintf(stderr, "%s: iblock->child_free_space = %Hu\n", "H5HF_man_dblock_adj_free", iblock->child_free_space);
 #endif /* QAK */
-        iblock->dblock_ents[dblock->parent_entry].free_space += amt;
+        iblock->ents[dblock->parent_entry].free_space += amt;
         iblock->child_free_space += amt;
 
         /* Mark indirect block as dirty */
@@ -867,7 +873,7 @@ HDfprintf(stderr, "%s: iblock->child_free_space = %Hu\n", "H5HF_man_dblock_adj_f
             HDassert(iblock);
 
             /* Adjust this indirect block's child free space */
-            iblock->iblock_ents[parent_entry].free_space += amt;
+            iblock->ents[parent_entry].free_space += amt;
             iblock->child_free_space += amt;
 
             /* Mark indirect block as dirty */
@@ -988,14 +994,10 @@ HDfprintf(stderr, "%s: dblock_size = %Zu\n", FUNC, dblock_size);
 
 #ifdef QAK
 HDfprintf(stderr, "%s: dblock_addr = %a\n", FUNC, dblock_addr);
-HDfprintf(stderr, "%s: shared->man_dtable.next_dir_block = %Hu\n", FUNC, shared->man_dtable.next_dir_block);
 #endif /* QAK */
 
         /* Point indirect block at new direct block */
-        iblock->dblock_ents[dblock_entry].addr = dblock_addr;
-
-        /* Increment size of next block from this indirect block */
-        H5HF_man_iblock_inc_loc(iblock);
+        iblock->ents[dblock_entry].addr = dblock_addr;
 
         /* Mark indirect block as modified */
         iblock->dirty = TRUE;
@@ -1287,8 +1289,14 @@ done:
 herr_t
 H5HF_man_read(H5RC_t *fh_shared, hid_t dxpl_id, hsize_t obj_off, void *obj)
 {
+    H5HF_parent_shared_t par_shared;    /* Parent shared information */
     H5HF_shared_t *shared;              /* Pointer to shared heap info */
-    unsigned row, col;                  /* Row & column for object's block */
+    H5HF_direct_t *dblock;              /* Pointer to direct block to query */
+    size_t blk_off;                     /* Offset of object in block */
+    uint8_t *p;                         /* Temporary pointer to obj info in block */
+    size_t obj_size;                    /* Size of object */
+    haddr_t dblock_addr;                /* Direct block address */
+    size_t dblock_size;                 /* Direct block size */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5HF_man_read)
@@ -1306,52 +1314,125 @@ H5HF_man_read(H5RC_t *fh_shared, hid_t dxpl_id, hsize_t obj_off, void *obj)
 
     /* Check for root direct block */
     if(shared->man_dtable.curr_root_rows == 0) {
-        H5HF_parent_shared_t par_shared;    /* Parent shared information */
-        H5HF_direct_t *dblock;          /* Pointer to direct block to query */
-        size_t blk_off;                 /* Offset of object in block */
-        uint8_t *p;                     /* Temporary pointer to obj info in block */
-        size_t obj_size;                /* Size of object */
+        /* Set direct block info */
+        par_shared.shared = fh_shared;
+        par_shared.parent = NULL;
+        par_shared.parent_entry = 0;
+        par_shared.parent_free_space = shared->total_man_free;
+
+        dblock_addr =  shared->man_dtable.table_addr;
+        dblock_size =  shared->man_dtable.cparam.start_block_size;
+
+        /* Lock direct block */
+        if(NULL == (dblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_DBLOCK, dblock_addr, &dblock_size, &par_shared, H5AC_READ)))
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect fractal heap direct block")
+    } /* end if */
+    else {
+        haddr_t iblock_addr;            /* Indirect block's address */
+        H5HF_indirect_t *iblock;        /* Pointer to indirect block */
+        unsigned row, col;              /* Row & column for object's block */
+        size_t entry;                   /* Entry of block */
 
-#ifdef QAK
         /* Look up row & column for object */
         if(H5HF_dtable_lookup(&shared->man_dtable, obj_off, &row, &col) < 0)
             HGOTO_ERROR(H5E_HEAP, H5E_CANTCOMPUTE, FAIL, "can't compute row & column of object")
+#ifdef QAK
 HDfprintf(stderr, "%s: row = %u, col = %u\n", FUNC, row, col);
 #endif /* QAK */
 
-        /* Lock first (root) direct block */
+        /* Set initial indirect block info */
+        iblock_addr = shared->man_dtable.table_addr;
+
+        /* Lock indirect block */
         par_shared.shared = fh_shared;
         par_shared.parent = NULL;
         par_shared.parent_entry = 0;
         par_shared.parent_free_space = shared->total_man_free;
-        if(NULL == (dblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_DBLOCK, shared->man_dtable.table_addr, &shared->man_dtable.cparam.start_block_size, &par_shared, H5AC_READ)))
-            HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap direct block")
+        if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, &shared->man_dtable.curr_root_rows, &par_shared, H5AC_READ)))
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect fractal heap indirect block")
 
-        /* Compute offset of object within block */
-        HDassert((obj_off - dblock->block_off) < (hsize_t)shared->man_dtable.cparam.start_block_size);
-        blk_off = (size_t)(obj_off - dblock->block_off);
+        /* Check for indirect block row */
+        while(row >= shared->man_dtable.max_direct_rows) {
+            haddr_t new_iblock_addr;       /* New indirect block's address */
+            H5HF_indirect_t *new_iblock;   /* Pointer to new indirect block */
+            unsigned nrows;                /* Number of rows in new indirect block */
 
-        /* Point to location for object */
-        p = dblock->blk + blk_off;
+            /* Compute # of rows in child indirect block */
+            nrows = (H5V_log2_gen(shared->man_dtable.row_block_size[row]) - shared->man_dtable.first_row_bits) + 1;
 
-        /* Decode the length */
-        UINT64DECODE_VAR(p, obj_size, dblock->blk_off_size);
+            /* Compute indirect block's entry */
+            entry = (row * shared->man_dtable.cparam.width) + col;
 
-        /* Skip over the free fragment size & ref count */
-        p += 1 + (shared->ref_count_obj ?  shared->ref_count_size : 0);
+            /* Locate child indirect block */
+            new_iblock_addr = iblock->ents[entry].addr;
 
-        /* Copy the object's data into the heap */
-        HDmemcpy(obj, p, obj_size);
+            /* Lock new indirect block */
+            par_shared.shared = fh_shared;
+            par_shared.parent = iblock->self;
+            par_shared.parent_entry = entry;
+            par_shared.parent_free_space = iblock->ents[entry].free_space;
+            if(NULL == (new_iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, new_iblock_addr, &nrows, &par_shared, H5AC_READ)))
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect fractal heap indirect block")
+
+            /* Release the current indirect block (possibly marked as dirty) */
+            if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, iblock, H5AC__NO_FLAGS_SET) < 0)
+                HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, FAIL, "unable to release fractal heap indirect block")
+
+            /* Switch variables to use new indirect block */
+            iblock = new_iblock;
+            iblock_addr = new_iblock_addr;
+
+            /* Look up row & column in new indirect block for object */
+            if(H5HF_dtable_lookup(&shared->man_dtable, (obj_off - iblock->block_off), &row, &col) < 0)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTCOMPUTE, FAIL, "can't compute row & column of object")
+        } /* end while */
 
-        /* Unlock first (root) direct block */
-        if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_DBLOCK, shared->man_dtable.table_addr, dblock, H5AC__NO_FLAGS_SET) < 0)
-            HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, NULL, "unable to release fractal heap direct block")
-        dblock = NULL;
-    } /* end if */
-    else {
-HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, FAIL, "root indirect blocks not supported yet")
+        /* Compute direct block's entry */
+        entry = (row * shared->man_dtable.cparam.width) + col;
+#ifdef QAK
+HDfprintf(stderr, "%s: entry address = %a\n", FUNC, iblock->dblock_ents[entry].addr);
+#endif /* QAK */
+
+        /* Set direct block info */
+        par_shared.shared = fh_shared;
+        par_shared.parent = iblock->self;
+        par_shared.parent_entry = entry;
+        par_shared.parent_free_space = iblock->ents[entry].free_space;
+
+        dblock_addr =  iblock->ents[entry].addr;
+        dblock_size =  shared->man_dtable.row_block_size[row];
+
+        /* Lock direct block */
+        if(NULL == (dblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_DBLOCK, dblock_addr, &dblock_size, &par_shared, H5AC_READ)))
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "unable to protect fractal heap direct block")
+
+        /* Unlock indirect block */
+        if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, iblock, H5AC__NO_FLAGS_SET) < 0)
+            HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, FAIL, "unable to release fractal heap indirect block")
+        iblock = NULL;
     } /* end else */
 
+    /* Compute offset of object within block */
+    HDassert((obj_off - dblock->block_off) < (hsize_t)dblock_size);
+    blk_off = (size_t)(obj_off - dblock->block_off);
+
+    /* Point to location for object */
+    p = dblock->blk + blk_off;
+
+    /* Decode the length */
+    UINT64DECODE_VAR(p, obj_size, dblock->blk_off_size);
+
+    /* Skip over the free fragment size & ref count */
+    p += 1 + (shared->ref_count_obj ?  shared->ref_count_size : 0);
+
+    /* Copy the object's data into the heap */
+    HDmemcpy(obj, p, obj_size);
+
+    /* Unlock direct block */
+    if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_DBLOCK, dblock_addr, dblock, H5AC__NO_FLAGS_SET) < 0)
+        HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, FAIL, "unable to release fractal heap direct block")
+    dblock = NULL;
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5HF_man_read() */
@@ -1390,10 +1471,8 @@ HDfprintf(stderr, "%s: Freeing indirect block\n", "H5HF_iblock_free");
         H5RC_DEC(iblock->parent);
 
     /* Release entry tables */
-    if(iblock->dblock_ents)
-        H5FL_SEQ_FREE(H5HF_indirect_dblock_ent_t, iblock->dblock_ents);
-    if(iblock->iblock_ents)
-        H5FL_SEQ_FREE(H5HF_indirect_iblock_ent_t, iblock->iblock_ents);
+    if(iblock->ents)
+        H5FL_SEQ_FREE(H5HF_indirect_ent_t, iblock->ents);
 
     /* Free fractal heap indirect block info */
     H5FL_FREE(H5HF_indirect_t, iblock);
@@ -1425,6 +1504,7 @@ H5HF_man_iblock_place_dblock(H5RC_t *fh_shared, hid_t dxpl_id,
     H5HF_parent_shared_t par_shared;    /* Parent shared information */
     H5HF_shared_t *shared;              /* Pointer to shared heap info */
     H5HF_indirect_t *iblock;            /* Pointer to indirect block */
+    haddr_t iblock_addr;                /* Indirect block's address */
     H5HF_indirect_t *ret_value;         /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT(H5HF_man_iblock_place_dblock)
@@ -1445,26 +1525,20 @@ H5HF_man_iblock_place_dblock(H5RC_t *fh_shared, hid_t dxpl_id,
         H5HF_direct_t *dblock;          /* Pointer to direct block to query */
         unsigned nrows;                 /* Number of rows for root indirect block */
 
-        /* Check for skipping over blocks */
-        if(min_dblock_size != shared->man_dtable.cparam.start_block_size) {
-HDfprintf(stderr, "%s: Skipping direct block sizes not supported\n", FUNC);
-HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, NULL, "skipping direct block sizes not supported yet")
-        } /* end if */
-
 #ifdef QAK
 HDfprintf(stderr, "%s: creating first indirect block\n", FUNC);
 #endif /* QAK */
         /* Check for allocating entire root indirect block initially */
         if(shared->man_dtable.cparam.start_root_rows == 0)
-            nrows = shared->man_dtable.max_root_indirect_rows;
+            nrows = shared->man_dtable.max_root_rows;
         else
             nrows = shared->man_dtable.cparam.start_root_rows;
 
         /* Allocate root indirect block */
-        if(H5HF_man_iblock_create(fh_shared, dxpl_id, (hsize_t)0, nrows, shared->man_dtable.max_direct_rows, addr_p) < 0)
+        if(H5HF_man_iblock_create(fh_shared, dxpl_id, (hsize_t)0, nrows, shared->man_dtable.max_root_rows, &iblock_addr) < 0)
             HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate fractal heap indirect block")
 #ifdef QAK
-HDfprintf(stderr, "%s: *addr_p = %a\n", FUNC, *addr_p);
+HDfprintf(stderr, "%s: iblock_addr = %a\n", FUNC, iblock_addr);
 #endif /* QAK */
 
         /* Move current direct block (used as root) into new indirect block */
@@ -1474,7 +1548,7 @@ HDfprintf(stderr, "%s: *addr_p = %a\n", FUNC, *addr_p);
         par_shared.parent = NULL;
         par_shared.parent_entry = 0;
         par_shared.parent_free_space = 0;
-        if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, *addr_p, &nrows, &par_shared, H5AC_WRITE)))
+        if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, &nrows, &par_shared, H5AC_WRITE)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap indirect block")
 
         /* Lock first (root) direct block */
@@ -1483,8 +1557,8 @@ HDfprintf(stderr, "%s: *addr_p = %a\n", FUNC, *addr_p);
             HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap direct block")
 
         /* Point indirect block at direct block to add */
-        iblock->dblock_ents[0].addr = shared->man_dtable.table_addr;
-        iblock->dblock_ents[0].free_space = dblock->blk_free_space;
+        iblock->ents[0].addr = shared->man_dtable.table_addr;
+        iblock->ents[0].free_space = dblock->blk_free_space;
         iblock->child_free_space += dblock->blk_free_space;
 
         /* Make direct block share parent indirect block */
@@ -1499,23 +1573,18 @@ HDfprintf(stderr, "%s: *addr_p = %a\n", FUNC, *addr_p);
 
         /* Increment size of next block from this indirect block */
         /* (account for the already existing direct block */
-        H5HF_man_iblock_inc_loc(iblock);
+        if(H5HF_man_iblock_inc_loc(iblock) < 0)
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTINC, NULL, "can't advance fractal heap block location")
 
         /* Mark indirect block as modified */
         iblock->dirty = TRUE;
 
         /* Point heap header at new indirect block */
         shared->man_dtable.curr_root_rows = nrows;
-        shared->man_dtable.table_addr = *addr_p;
+        shared->man_dtable.table_addr = iblock_addr;
 
         /* Mark heap header as modified */
         shared->dirty = TRUE;
-
-        /* Set entry for direct block */
-        *entry_p = 1;
-
-        /* Set size of direct block to create */
-        *dblock_size = iblock->next_dir_size;
     } /* end if */
     else {
 #ifdef QAK
@@ -1527,62 +1596,44 @@ HDfprintf(stderr, "%s: searching root indirect block\n", FUNC);
         par_shared.parent = NULL;
         par_shared.parent_entry = 0;
         par_shared.parent_free_space = shared->total_man_free;
-        if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, shared->man_dtable.table_addr, &shared->man_dtable.curr_root_rows, &par_shared, H5AC_WRITE)))
+        iblock_addr = shared->man_dtable.table_addr;
+        if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, &shared->man_dtable.curr_root_rows, &par_shared, H5AC_WRITE)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap indirect block")
 
 #ifdef QAK
-HDfprintf(stderr, "%s: iblock->next_dir_row = %u\n", FUNC, iblock->next_dir_row);
-HDfprintf(stderr, "%s: iblock->next_dir_col = %u\n", FUNC, iblock->next_dir_col);
-HDfprintf(stderr, "%s: iblock->next_dir_size = %Zu\n", FUNC, iblock->next_dir_size);
-HDfprintf(stderr, "%s: iblock->dir_full = %u\n", FUNC, (unsigned)iblock->dir_full);
+HDfprintf(stderr, "%s: iblock->nrows = %u\n", FUNC, iblock->nrows);
 #endif /* QAK */
-         /* Check for full direct block entries in root */
-         if(iblock->dir_full) {
-HDfprintf(stderr, "%s: Adding nested indirect block to heap not supported\n", FUNC);
-HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, NULL, "Adding nested indirect block not supported yet")
-         } /* end if */
-
-        /* Check for skipping over blocks */
-        if(min_dblock_size > iblock->next_dir_size) {
-HDfprintf(stderr, "%s: Skipping direct block sizes not supported\n", FUNC);
-HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, NULL, "skipping direct block sizes not supported yet")
-        } /* end if */
-
-        /* Check if we need a direct block past current allocation */
-        if(iblock->next_dir_row == iblock->ndir_rows) {
-            haddr_t old_addr;           /* Old address of indirect block */
+        /* Check if we need a block past current allocation */
+        if(iblock->next_row == iblock->nrows) {
             haddr_t new_addr;           /* New address of indirect block */
             unsigned new_nrows;         /* New # of direct rows */
             size_t u;                   /* Local index variable */
 
             /* Check for special case of second row, which has blocks the same size as first row */
-            if(iblock->next_dir_row == 1)
-                iblock->next_dir_size = shared->man_dtable.cparam.start_block_size;
+            if(iblock->next_row == 1)
+                iblock->next_size = shared->man_dtable.cparam.start_block_size;
 
             /* Compute new # of rows in indirect block */
-            new_nrows = 2 * iblock->ndir_rows;
-            if(new_nrows > iblock->max_direct_rows)
-                new_nrows = iblock->max_direct_rows;
+            new_nrows = MIN(2 * iblock->nrows, iblock->max_rows);
 #ifdef QAK
 HDfprintf(stderr, "%s: new_nrows = %u\n", FUNC, new_nrows);
 #endif /* QAK */
 
 /* Currently, the old chunk data is "thrown away" after the space is reallocated,
- * so avoid data copy in H5MF_realloc() call by just free'ing the space and
- * allocating new space.
- *
- * This should keep the file smaller also, by freeing the space and then
- * allocating new space, instead of vice versa (in H5MF_realloc).
- *
- * QAK - 3/14/2006
- */
+* so avoid data copy in H5MF_realloc() call by just free'ing the space and
+* allocating new space.
+*
+* This should keep the file smaller also, by freeing the space and then
+* allocating new space, instead of vice versa (in H5MF_realloc).
+*
+* QAK - 3/14/2006
+*/
             /* Free previous indirect block disk space */
-            old_addr = shared->man_dtable.table_addr;
-            if(H5MF_xfree(shared->f, H5FD_MEM_FHEAP_IBLOCK, dxpl_id, old_addr, (hsize_t)iblock->size)<0)
+            if(H5MF_xfree(shared->f, H5FD_MEM_FHEAP_IBLOCK, dxpl_id, iblock_addr, (hsize_t)iblock->size)<0)
                 HGOTO_ERROR(H5E_STORAGE, H5E_CANTFREE, NULL, "unable to free fractal heap indirect block")
 
             /* Compute size of buffer needed for new indirect block */
-            iblock->ndir_rows = new_nrows;
+            iblock->nrows = new_nrows;
             iblock->size = H5HF_MAN_INDIRECT_SIZE(shared, iblock);
 
             /* Allocate space for the new indirect block on disk */
@@ -1590,31 +1641,31 @@ HDfprintf(stderr, "%s: new_nrows = %u\n", FUNC, new_nrows);
                 HGOTO_ERROR(H5E_STORAGE, H5E_NOSPACE, NULL, "file allocation failed for fractal heap indirect block")
 
             /* Re-allocate direct block entry table */
-            if(NULL == (iblock->dblock_ents = H5FL_SEQ_REALLOC(H5HF_indirect_dblock_ent_t, iblock->dblock_ents, (iblock->ndir_rows * shared->man_dtable.cparam.width))))
+            if(NULL == (iblock->ents = H5FL_SEQ_REALLOC(H5HF_indirect_ent_t, iblock->ents, (iblock->nrows * shared->man_dtable.cparam.width))))
                 HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for direct entries")
 
             /* Initialize new direct block entries */
-            for(u = (iblock->next_dir_row * shared->man_dtable.cparam.width);
-                    u < (iblock->ndir_rows * shared->man_dtable.cparam.width);
+            for(u = (iblock->next_row * shared->man_dtable.cparam.width);
+                    u < (iblock->nrows * shared->man_dtable.cparam.width);
                     u++) {
-                iblock->dblock_ents[u].addr = HADDR_UNDEF;
-                iblock->dblock_ents[u].free_space = 0;
+                iblock->ents[u].addr = HADDR_UNDEF;
+                iblock->ents[u].free_space = 0;
             } /* end for */
 
             /* Mark indirect block as dirty */
             iblock->dirty = TRUE;
 
             /* Release the indirect block (marked as dirty) */
-            if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, old_addr, iblock, H5AC__DIRTIED_FLAG) < 0)
+            if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, iblock, H5AC__DIRTIED_FLAG) < 0)
                 HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, NULL, "unable to release fractal heap indirect block")
 
             /* Move object in cache */
-            if(H5AC_rename(shared->f, H5AC_FHEAP_IBLOCK, old_addr, new_addr) < 0)
+            if(H5AC_rename(shared->f, H5AC_FHEAP_IBLOCK, iblock_addr, new_addr) < 0)
                 HGOTO_ERROR(H5E_HEAP, H5E_CANTSPLIT, NULL, "unable to move fractal heap root indirect block")
 
             /* Update other shared header info */
             shared->man_dtable.curr_root_rows = new_nrows;
-            shared->man_dtable.table_addr = new_addr;
+            shared->man_dtable.table_addr = iblock_addr = new_addr;
 
             /* Mark heap header as modified */
             shared->dirty = TRUE;
@@ -1624,20 +1675,113 @@ HDfprintf(stderr, "%s: new_nrows = %u\n", FUNC, new_nrows);
             par_shared.parent = NULL;
             par_shared.parent_entry = 0;
             par_shared.parent_free_space = shared->total_man_free;
-            if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, shared->man_dtable.table_addr, &shared->man_dtable.curr_root_rows, &par_shared, H5AC_WRITE)))
+            if(NULL == (iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, &shared->man_dtable.curr_root_rows, &par_shared, H5AC_WRITE)))
                 HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap indirect block")
         } /* end if */
 
-        /* Set address of indirect block */
-        *addr_p = shared->man_dtable.table_addr;
+#ifdef QAK
+HDfprintf(stderr, "%s: iblock->next_row = %u\n", FUNC, iblock->next_row);
+HDfprintf(stderr, "%s: iblock->next_col = %u\n", FUNC, iblock->next_col);
+HDfprintf(stderr, "%s: iblock->next_size = %Zu\n", FUNC, iblock->next_size);
+HDfprintf(stderr, "%s: iblock->next_entry = %u\n", FUNC, iblock->next_entry);
+#endif /* QAK */
+        /* Check for full direct block entries in current indirect block */
+        while(iblock->next_row >= shared->man_dtable.max_direct_rows) {
+            haddr_t new_iblock_addr;       /* New indirect block's address */
+            H5HF_indirect_t *new_iblock;   /* Pointer to new indirect block */
+            unsigned hdr_flags = H5AC__NO_FLAGS_SET;    /* Metadata cache flags for header */
+            unsigned nrows;                /* Number of rows in new indirect block */
+
+            /* Compute # of rows in child indirect block */
+            nrows = (H5V_log2_gen(iblock->next_size) - shared->man_dtable.first_row_bits) + 1;
+#ifdef QAK
+HDfprintf(stderr, "%s: iblock->next_size = %Hu, nrows = %u\n", FUNC, iblock->next_size, nrows);
+#endif /* QAK */
+
+            /* Check for allocating new indirect block */
+            if(!H5F_addr_defined(iblock->ents[iblock->next_entry].addr)) {
+#ifdef QAK
+HDfprintf(stderr, "%s: Allocating new indirect block\n", FUNC);
+#endif /* QAK */
+                /* Allocate new indirect block */
+                if(H5HF_man_iblock_create(fh_shared, dxpl_id, shared->man_dtable.next_dir_block, nrows, nrows, &new_iblock_addr) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate fractal heap indirect block")
+
+                /* Lock new indirect block */
+                par_shared.shared = fh_shared;
+                par_shared.parent = iblock->self;
+                par_shared.parent_entry = iblock->next_entry;
+                par_shared.parent_free_space = 0;
+                if(NULL == (new_iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, new_iblock_addr, &nrows, &par_shared, H5AC_WRITE)))
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap indirect block")
+#ifdef QAK
+HDfprintf(stderr, "%s: new_iblock->next_row = %u\n", FUNC, new_iblock->next_row);
+HDfprintf(stderr, "%s: new_iblock->next_col = %u\n", FUNC, new_iblock->next_col);
+HDfprintf(stderr, "%s: new_iblock->next_size = %Zu\n", FUNC, new_iblock->next_size);
+HDfprintf(stderr, "%s: new_iblock->next_entry = %u\n", FUNC, new_iblock->next_entry);
+#endif /* QAK */
+
+                /* Point current indirect block at new indirect block */
+                iblock->ents[iblock->next_entry].addr = new_iblock_addr;
 
-        /* Set entry for direct block */
-        *entry_p = iblock->next_dir_entry;
+                /* Increment location of next block from current indirect block */
+                if(H5HF_man_iblock_inc_loc(iblock) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTINC, NULL, "can't advance fractal heap block location")
 
-        /* Set size of direct block to create */
-        *dblock_size = iblock->next_dir_size;
+                /* Mark current indirect block as modified */
+                iblock->dirty = TRUE;
+
+                /* Release the current indirect block (marked as dirty) */
+                hdr_flags |= H5AC__DIRTIED_FLAG;
+            } /* end if */
+            else {
+#ifdef QAK
+HDfprintf(stderr, "%s: Descending existing indirect block\n", FUNC);
+#endif /* QAK */
+                /* Locate child indirect block */
+                new_iblock_addr = iblock->ents[iblock->next_entry].addr;
+
+                /* Lock new indirect block */
+                par_shared.shared = fh_shared;
+                par_shared.parent = iblock->self;
+                par_shared.parent_entry = iblock->next_entry;
+                par_shared.parent_free_space = iblock->ents[iblock->next_entry].free_space;
+                if(NULL == (new_iblock = H5AC_protect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, new_iblock_addr, &nrows, &par_shared, H5AC_WRITE)))
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, NULL, "unable to protect fractal heap indirect block")
+             } /* end else */
+
+            /* Release the current indirect block (possibly marked as dirty) */
+            if(H5AC_unprotect(shared->f, dxpl_id, H5AC_FHEAP_IBLOCK, iblock_addr, iblock, hdr_flags) < 0)
+                HDONE_ERROR(H5E_HEAP, H5E_CANTUNPROTECT, NULL, "unable to release fractal heap indirect block")
+
+            /* Switch variables to use new indirect block */
+            iblock = new_iblock;
+            iblock_addr = new_iblock_addr;
+#ifdef QAK
+HDfprintf(stderr, "%s: new_iblock_addr = %a\n", FUNC, new_iblock_addr);
+#endif /* QAK */
+        } /* end while */
     } /* end else */
 
+    /* Check for skipping over blocks */
+    if(min_dblock_size > iblock->next_size) {
+HDfprintf(stderr, "%s: Skipping direct block sizes not supported\n", FUNC);
+HGOTO_ERROR(H5E_HEAP, H5E_UNSUPPORTED, NULL, "skipping direct block sizes not supported yet")
+    } /* end if */
+
+    /* Set address of indirect block that's the immediate parent of new direct block */
+    *addr_p = iblock_addr;
+
+    /* Set entry for new direct block to use */
+    *entry_p = iblock->next_entry;
+
+    /* Set size of direct block to create */
+    *dblock_size = iblock->next_size;
+
+    /* Increment location of next block from this indirect block */
+    if(H5HF_man_iblock_inc_loc(iblock) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTINC, NULL, "can't advance fractal heap block location")
+
     /* Set return value */
     ret_value = iblock;
 
@@ -1661,7 +1805,7 @@ done:
  */
 static herr_t
 H5HF_man_iblock_create(H5RC_t *fh_shared, hid_t dxpl_id,
-    hsize_t block_off, unsigned nrows, unsigned max_dir_rows, haddr_t *addr_p)
+    hsize_t block_off, unsigned nrows, unsigned max_rows, haddr_t *addr_p)
 {
     H5HF_shared_t *shared;              /* Pointer to shared heap info */
     H5HF_indirect_t *iblock = NULL;     /* Pointer to indirect block */
@@ -1699,7 +1843,7 @@ H5HF_man_iblock_create(H5RC_t *fh_shared, hid_t dxpl_id,
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't create ref-count wrapper for indirect fractal heap block")
 
 #ifdef QAK
-HDfprintf(stderr, "%s: nrows = %u\n", FUNC, nrows);
+HDfprintf(stderr, "%s: nrows = %u, max_nrows = %u\n", FUNC, nrows, max_nrows);
 #endif /* QAK */
     /* Set info for direct block */
     iblock->parent = NULL;              /* Temporary, except for root indirect block */
@@ -1707,41 +1851,24 @@ HDfprintf(stderr, "%s: nrows = %u\n", FUNC, nrows);
     iblock->block_off = block_off;
     iblock->child_free_space = 0;
     iblock->nrows = nrows;
-    iblock->dir_full = FALSE;
-    iblock->next_dir_col = 0;
-    iblock->next_dir_row = 0;
-    iblock->next_dir_entry = 0;
-    iblock->next_dir_size = shared->man_dtable.cparam.start_block_size;
-    iblock->max_direct_rows = max_dir_rows;
-    if(iblock->nrows > shared->man_dtable.max_direct_rows) {
-        iblock->ndir_rows = shared->man_dtable.max_direct_rows;
-        iblock->nindir_rows = iblock->nrows - iblock->ndir_rows;
-    } /* end if */
-    else {
-        iblock->ndir_rows = iblock->nrows;
-        iblock->nindir_rows = 0;
-    } /* end else */
+    iblock->max_rows = max_rows;
+    iblock->next_col = 0;
+    iblock->next_row = 0;
+    iblock->next_entry = 0;
+    iblock->next_size = shared->man_dtable.cparam.start_block_size;
 
     /* Compute size of buffer needed for indirect block */
     iblock->size = H5HF_MAN_INDIRECT_SIZE(shared, iblock);
 
     /* Allocate indirect block entry tables */
-    if(NULL == (iblock->dblock_ents = H5FL_SEQ_MALLOC(H5HF_indirect_dblock_ent_t, (iblock->ndir_rows * shared->man_dtable.cparam.width))))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for direct entries")
-    if(iblock->nindir_rows > 0) {
-        if(NULL == (iblock->iblock_ents = H5FL_SEQ_MALLOC(H5HF_indirect_iblock_ent_t, (iblock->nindir_rows * shared->man_dtable.cparam.width))))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for indirect entries")
-    } /* end if */
-    else
-        iblock->iblock_ents = NULL;
+    if(NULL == (iblock->ents = H5FL_SEQ_MALLOC(H5HF_indirect_ent_t, (iblock->nrows * shared->man_dtable.cparam.width))))
+	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for block entries")
 
     /* Initialize indirect block entry tables */
-    for(u = 0; u < (iblock->ndir_rows * shared->man_dtable.cparam.width); u++) {
-        iblock->dblock_ents[u].addr = HADDR_UNDEF;
-        iblock->dblock_ents[u].free_space = 0;
+    for(u = 0; u < (iblock->nrows * shared->man_dtable.cparam.width); u++) {
+        iblock->ents[u].addr = HADDR_UNDEF;
+        iblock->ents[u].free_space = 0;
     } /* end for */
-    for(u = 0; u < (iblock->nindir_rows * shared->man_dtable.cparam.width); u++)
-        iblock->iblock_ents[u].addr = HADDR_UNDEF;
 
     /* Allocate space for the indirect block on disk */
     if(HADDR_UNDEF == (*addr_p = H5MF_alloc(shared->f, H5FD_MEM_FHEAP_IBLOCK, dxpl_id, (hsize_t)iblock->size)))
@@ -1751,7 +1878,6 @@ HDfprintf(stderr, "%s: nrows = %u\n", FUNC, nrows);
 #ifdef LATER
     /* Update shared heap info */
     shared->total_man_free += dblock->blk_free_space;
-    shared->man_dtable.next_dir_block += dblock->size;
     shared->total_size += dblock->size;
     shared->man_size += dblock->size;
 
diff --git a/src/H5HFpkg.h b/src/H5HFpkg.h
index 33a9d37..175b521 100644
--- a/src/H5HFpkg.h
+++ b/src/H5HFpkg.h
@@ -57,19 +57,19 @@
     )
 
 /* Size of doubling-table information */
-#define H5HF_DTABLE_INFO_SIZE(f) (                                            \
+#define H5HF_DTABLE_INFO_SIZE(s) (                                            \
     2   /* Width of table (i.e. # of columns) */                              \
-    + H5F_SIZEOF_SIZE(f) /* Starting block size */                            \
-    + H5F_SIZEOF_SIZE(f) /* Maximum direct block size */                      \
+    + (s)->sizeof_size /* Starting block size */                            \
+    + (s)->sizeof_size /* Maximum direct block size */                      \
     + 2 /* Max. size of heap (log2 of actual value - i.e. the # of bits) */   \
     + 2 /* Starting # of rows in root indirect block */                       \
-    + H5F_SIZEOF_ADDR(f) /* File address of table managed */                  \
+    + (s)->sizeof_addr /* File address of table managed */                  \
     + 2 /* Current # of rows in root indirect block */                        \
-    + H5F_SIZEOF_SIZE(f) /* Next direct block's heap offset */                \
+    + (s)->sizeof_size /* Next direct block's heap offset */                \
     )
 
 /* Size of the fractal heap header on disk */
-#define H5HF_HEADER_SIZE(f)     (                                             \
+#define H5HF_HEADER_SIZE(s)     (                                             \
     /* General metadata fields */                                             \
     H5HF_METADATA_PREFIX_SIZE                                                 \
                                                                               \
@@ -77,13 +77,13 @@
     + 1 /* Address mapping */                                                 \
     + 4 /* Min. size of standalone object */                                  \
     + 1 /* Size of ref. count for objects */                                  \
-    + H5F_SIZEOF_SIZE(f) /* Total man. free space */                          \
-    + H5F_SIZEOF_SIZE(f) /* Total std. free entries */                        \
-    + H5F_SIZEOF_SIZE(f) /* Total size of heap */                             \
-    + H5F_SIZEOF_SIZE(f) /* Size of man. space in heap */                     \
-    + H5F_SIZEOF_SIZE(f) /* Size of std. space in heap */                     \
-    + H5F_SIZEOF_SIZE(f) /* Number of objects in heap */                      \
-    + H5HF_DTABLE_INFO_SIZE(f) /* Size of managed obj. doubling-table info */ \
+    + (s)->sizeof_size /* Total man. free space */                          \
+    + (s)->sizeof_size /* Total std. free entries */                        \
+    + (s)->sizeof_size /* Total size of heap */                             \
+    + (s)->sizeof_size /* Size of man. space in heap */                     \
+    + (s)->sizeof_size /* Size of std. space in heap */                     \
+    + (s)->sizeof_size /* Number of objects in heap */                      \
+    + H5HF_DTABLE_INFO_SIZE(s) /* Size of managed obj. doubling-table info */ \
     )
 
 /* Size of free space description in an absolute managed direct block */
@@ -107,7 +107,7 @@
     H5HF_METADATA_PREFIX_SIZE                                                 \
                                                                               \
     /* Fractal heap managed, absolutely mapped direct block specific fields */ \
-    + H5F_SIZEOF_ADDR((s)->f)   /* File address of heap owning the block */   \
+    + (s)->sizeof_addr          /* File address of heap owning the block */   \
     + (s)->heap_off_size        /* Offset of the block in the heap */         \
     + H5HF_SIZEOF_OFFSET_LEN(o) /* Total free space in a block */             \
     + H5HF_SIZEOF_OFFSET_LEN(o) /* Offset of first descriptor in free list */ \
@@ -117,7 +117,7 @@
     H5HF_METADATA_PREFIX_SIZE                                                 \
                                                                               \
     /* Fractal heap managed, absolutely mapped direct block specific fields */ \
-    + H5F_SIZEOF_ADDR((s)->f)   /* File address of heap owning the block */   \
+    + (s)->sizeof_addr          /* File address of heap owning the block */   \
     + (s)->heap_off_size        /* Offset of the block in the heap */         \
     + (d)->blk_off_size         /* Offset of first descriptor in free list */ \
     )
@@ -128,10 +128,11 @@
     H5HF_METADATA_PREFIX_SIZE                                                 \
                                                                               \
     /* Fractal heap managed, absolutely mapped indirect block specific fields */ \
-    + H5F_SIZEOF_ADDR((s)->f)   /* File address of heap owning the block */   \
+    + (s)->sizeof_addr          /* File address of heap owning the block */   \
     + (s)->heap_off_size        /* Offset of the block in the heap */         \
-    + ((i)->ndir_rows * (s)->man_dtable.cparam.width * (H5F_SIZEOF_ADDR((s)->f) + (s)->man_dtable.max_dir_blk_off_size)) /* Size of entries for direct blocks */ \
-    + ((i)->nindir_rows * (s)->man_dtable.cparam.width * (H5F_SIZEOF_ADDR((s)->f) + (s)->heap_off_size)) /* Size of entries for indirect blocks */ \
+    + 4                         /* Next block entry to allocate from */       \
+    + (MIN((i)->nrows, (s)->man_dtable.max_direct_rows) * (s)->man_dtable.cparam.width * ((s)->sizeof_addr + (s)->man_dtable.max_dir_blk_off_size)) /* Size of entries for direct blocks */ \
+    + ((((i)->nrows > (s)->man_dtable.max_direct_rows) ? ((i)->nrows - (s)->man_dtable.max_direct_rows) : 0)  * (s)->man_dtable.cparam.width * ((s)->sizeof_addr + (s)->heap_off_size)) /* Size of entries for indirect blocks */ \
     )
 
 
@@ -160,7 +161,7 @@ typedef struct H5HF_dtable_t {
     hsize_t     next_dir_block; /* Offset of next direct managed block */
 
     /* Computed information (not stored) */
-    unsigned    max_root_indirect_rows; /* Maximum # of rows in root indirect block */
+    unsigned    max_root_rows;  /* Maximum # of rows in root indirect block */
     unsigned    max_direct_rows; /* Maximum # of direct rows in any indirect block */
     unsigned    max_dir_blk_off_size;   /* Max. size of offsets in direct blocks */
     unsigned    first_row_bits;  /* # of bits in address of first row */
@@ -192,6 +193,8 @@ typedef struct H5HF_shared_t {
     hbool_t     dirty;          /* Shared info is modified */
     haddr_t     heap_addr;      /* Address of heap header in the file */
     H5F_t      *f;              /* Pointer to file for heap */
+    size_t      sizeof_size;    /* Size of file sizes */
+    size_t      sizeof_addr;    /* Size of file addresses */
     H5HF_freelist_t *flist;     /* Free list for objects in heap */
 
     /* Doubling table information */
@@ -256,18 +259,12 @@ typedef struct H5HF_direct_t {
     size_t      free_list_head; /* Offset of head of free list in block       */
 } H5HF_direct_t;
 
-/* Indirect block direct block entry */
-typedef struct H5HF_indirect_dblock_ent_t {
+/* Indirect block entry */
+typedef struct H5HF_indirect_ent_t {
     haddr_t     addr;           /* Direct block's address                     */
-    size_t      free_space;     /* Amount of free space in direct block       */
+    hsize_t     free_space;     /* Amount of free space in block pointed to   */
 /* XXX: Will need space for block size, for blocks with I/O filters */
-} H5HF_indirect_dblock_ent_t;
-
-/* Indirect block indirect block entry */
-typedef struct H5HF_indirect_iblock_ent_t {
-    haddr_t     addr;           /* Indirect block's address                   */
-    hsize_t     free_space;     /* Amount of free space in indirect block child */
-} H5HF_indirect_iblock_ent_t;
+} H5HF_indirect_ent_t;
 
 /* Fractal heap indirect block */
 typedef struct H5HF_indirect_t {
@@ -281,17 +278,13 @@ typedef struct H5HF_indirect_t {
     size_t      parent_entry;   /* Entry in parent's table                    */
     H5RC_t	*self;		/* Ref-counted shared 'self' block info       */
     unsigned    nrows;          /* Total # of rows in indirect block          */
-    unsigned    ndir_rows;      /* # of direct rows in indirect block         */
-    unsigned    nindir_rows;    /* # of indirect rows in indirect block       */
+    unsigned    max_rows;       /* Max. # of rows in indirect block           */
     size_t      size;           /* Size of indirect block on disk             */
-    hbool_t     dir_full;       /* Flag to indicate that all direct blocks are allocated */
-    unsigned    next_dir_col;   /* "Column" of next managed direct block (in doubling table) */
-    unsigned    next_dir_row;   /* "Row" of next managed direct block (in doubling table) */
-    unsigned    next_dir_entry; /* Entry of next managed direct block         */
-    size_t      next_dir_size;  /* Size of next managed direct block          */
-    unsigned    max_direct_rows; /* Maximum # of direct rows in indirect block */
-    H5HF_indirect_dblock_ent_t *dblock_ents;    /* Pointer to direct block entry table */
-    H5HF_indirect_iblock_ent_t *iblock_ents;    /* Pointer to indirect block entry table */
+    unsigned    next_col;       /* "Column" of next managed block (in doubling table) */
+    unsigned    next_row;       /* "Row" of next managed block (in doubling table) */
+    unsigned    next_entry;     /* Entry of next managed block                */
+    hsize_t     next_size;      /* Size of next managed block                 */
+    H5HF_indirect_ent_t *ents;  /* Pointer to block entry table               */
 
     /* Stored values */
     hsize_t     block_off;      /* Offset of the block within the heap's address space */
@@ -347,11 +340,8 @@ H5FL_BLK_EXTERN(direct_block);
 /* Declare a free list to manage the H5HF_indirect_t struct */
 H5FL_EXTERN(H5HF_indirect_t);
 
-/* Declare a free list to manage the H5HF_indirect_dblock_ent_t sequence information */
-H5FL_SEQ_EXTERN(H5HF_indirect_dblock_ent_t);
-
-/* Declare a free list to manage the H5HF_indirect_iblock_ent_t sequence information */
-H5FL_SEQ_EXTERN(H5HF_indirect_iblock_ent_t);
+/* Declare a free list to manage the H5HF_indirect_ent_t sequence information */
+H5FL_SEQ_EXTERN(H5HF_indirect_ent_t);
 
 
 /******************************/
@@ -360,7 +350,7 @@ H5FL_SEQ_EXTERN(H5HF_indirect_iblock_ent_t);
 
 /* Routines for managing shared fractal heap info */
 H5_DLL H5HF_shared_t * H5HF_shared_alloc(H5F_t *f);
-H5_DLL herr_t H5HF_shared_create(H5F_t *f, H5HF_t *fh, haddr_t heap_addr, H5HF_create_t *cparam);
+H5_DLL herr_t H5HF_shared_init(H5HF_shared_t *shared, H5HF_t *fh, haddr_t heap_addr, H5HF_create_t *cparam);
 H5_DLL herr_t H5HF_shared_own(H5HF_t *fh, H5HF_shared_t *shared);
 
 /* Indirect block routines */
diff --git a/src/H5private.h b/src/H5private.h
index a67a6aa..8a10783 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -1192,12 +1192,23 @@ static herr_t		H5_INTERFACE_INIT_FUNC(void);
 #endif /* H5_INTERFACE_INIT_FUNC */
 
 
+#ifndef NDEBUG
 #define FUNC_ENTER_COMMON_NOFUNC(func_name,asrt)                              \
-   /* Check API status */               				      \
-   assert(asrt);				                              \
+    static hbool_t func_check = FALSE;          			      \
+									      \
+    if(!func_check) {			   				      \
+        /* Check API status */               				      \
+        HDassert(asrt);				                              \
+									      \
+        /* Check function name */               			      \
+        H5_CHECK_FUNCNAME(func_name);					      \
 									      \
-   /* Check function name */               				      \
-   H5_CHECK_FUNCNAME(func_name);
+        /* Don't check again */                 			      \
+        func_check = TRUE;						      \
+    } /* end if */
+#else /* NDEBUG */
+#define FUNC_ENTER_COMMON_NOFUNC(func_name,asrt)
+#endif /* NDEBUG */
 
 #define FUNC_ENTER_COMMON(func_name,asrt)                                     \
     static const char FUNC[]=#func_name;                                      \