[svn-r27237] Description:

    Merge v3 metadata cache changes to trunk.  Yay! :-)

Tested on:
    MacOSX/64 10.10.3 (amazon) w/serial & parallel
    Linux/32 2.6.x (jam) w/serial & parallel
    (daily tested on branch)

1 files changed, 1431 insertions, 991 deletions

diff --git a/src/H5HFcache.c b/src/H5HFcache.c
index 07e5b36..ec8d9a6 100644
--- a/src/H5HFcache.c
+++ b/src/H5HFcache.c
@@ -53,12 +53,6 @@
 #define H5HF_DBLOCK_VERSION     0               /* Direct block */
 #define H5HF_IBLOCK_VERSION     0               /* Indirect block */
 
-/* Size of stack buffer for serialized headers */
-#define H5HF_HDR_BUF_SIZE       512
-
-/* Size of stack buffer for serialized indirect blocks */
-#define H5HF_IBLOCK_BUF_SIZE    4096
-
 
 /******************/
 /* Local Typedefs */
@@ -79,24 +73,48 @@ static herr_t H5HF__dtable_encode(H5F_t *f, uint8_t **pp, const H5HF_dtable_t *d
 static herr_t H5HF__dtable_decode(H5F_t *f, const uint8_t **pp, H5HF_dtable_t *dtable);
 
 /* Metadata cache (H5AC) callbacks */
-static H5HF_hdr_t *H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *udata);
-static herr_t H5HF_cache_hdr_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HF_hdr_t *hdr, unsigned H5_ATTR_UNUSED * flags_ptr);
-static herr_t H5HF_cache_hdr_dest(H5F_t *f, H5HF_hdr_t *hdr);
-static herr_t H5HF_cache_hdr_clear(H5F_t *f, H5HF_hdr_t *hdr, hbool_t destroy);
-static herr_t H5HF_cache_hdr_size(const H5F_t *f, const H5HF_hdr_t *hdr, size_t *size_ptr);
-static H5HF_indirect_t *H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *udata);
-static herr_t H5HF_cache_iblock_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HF_indirect_t *iblock, unsigned H5_ATTR_UNUSED * flags_ptr);
-static herr_t H5HF_cache_iblock_dest(H5F_t *f, H5HF_indirect_t *iblock);
-static herr_t H5HF_cache_iblock_clear(H5F_t *f, H5HF_indirect_t *iblock, hbool_t destroy);
-static herr_t H5HF_cache_iblock_notify(H5C_notify_action_t action, H5HF_indirect_t *iblock);
-static herr_t H5HF_cache_iblock_size(const H5F_t *f, const H5HF_indirect_t *iblock, size_t *size_ptr);
-static H5HF_direct_t *H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *udata);
-static herr_t H5HF_cache_dblock_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HF_direct_t *dblock, unsigned H5_ATTR_UNUSED * flags_ptr);
-static herr_t H5HF_cache_dblock_dest(H5F_t *f, H5HF_direct_t *dblock);
-static herr_t H5HF_cache_dblock_clear(H5F_t *f, H5HF_direct_t *dblock, hbool_t destroy);
-static herr_t H5HF_cache_dblock_notify(H5C_notify_action_t action, H5HF_direct_t *dblock);
-static herr_t H5HF_cache_dblock_size(const H5F_t *f, const H5HF_direct_t *dblock, size_t *size_ptr);
-
+static herr_t H5HF__cache_hdr_get_load_size(const void *udata, size_t *image_len);
+static void *H5HF__cache_hdr_deserialize(const void *image, size_t len,
+    void *udata, hbool_t *dirty); 
+static herr_t H5HF__cache_hdr_image_len(const void *thing, size_t *image_len,
+    hbool_t *compressed_ptr, size_t *compressed_image_len_ptr);
+static herr_t H5HF__cache_hdr_pre_serialize(const H5F_t *f, hid_t dxpl_id,
+    void *thing, haddr_t addr, size_t len, size_t compressed_len, 
+    haddr_t *new_addr, size_t *new_len, size_t *new_compressed_len, 
+    unsigned *flags); 
+static herr_t H5HF__cache_hdr_serialize(const H5F_t *f, void *image,
+    size_t len, void *thing); 
+static herr_t H5HF__cache_hdr_free_icr(void *thing);
+
+static herr_t H5HF__cache_iblock_get_load_size(const void *udata, size_t *image_len);
+static void *H5HF__cache_iblock_deserialize(const void *image, size_t len,
+    void *udata, hbool_t *dirty); 
+static herr_t H5HF__cache_iblock_image_len(const void *thing, 
+    size_t *image_len, hbool_t *compressed_ptr, 
+    size_t *compressed_image_len_ptr);
+static herr_t H5HF__cache_iblock_pre_serialize(const H5F_t *f, hid_t dxpl_id,
+    void *thing, haddr_t addr, size_t len, size_t compressed_len, 
+    haddr_t *new_addr, size_t *new_len, size_t *new_compressed_len, 
+    unsigned *flags); 
+static herr_t H5HF__cache_iblock_serialize(const H5F_t *f, void *image,
+    size_t len, void *thing); 
+static herr_t H5HF__cache_iblock_notify(H5C_notify_action_t action, void *thing); 
+static herr_t H5HF__cache_iblock_free_icr(void *thing);
+
+static herr_t H5HF__cache_dblock_get_load_size(const void *udata, size_t *image_len);
+static void *H5HF__cache_dblock_deserialize(const void *image, size_t len,
+    void *udata, hbool_t *dirty); 
+static herr_t H5HF__cache_dblock_image_len(const void *thing, 
+    size_t *image_len, hbool_t *compressed_ptr, 
+    size_t *compressed_image_len_ptr);
+static herr_t H5HF__cache_dblock_pre_serialize(const H5F_t *f, hid_t dxpl_id,
+    void *thing, haddr_t addr, size_t len, size_t compressed_len,
+    haddr_t *new_addr, size_t *new_len, size_t *new_compressed_len, 
+    unsigned *flags); 
+static herr_t H5HF__cache_dblock_serialize(const H5F_t *f, void *image,
+    size_t len, void *thing); 
+static herr_t H5HF__cache_dblock_notify(H5C_notify_action_t action, void *thing);
+static herr_t H5HF__cache_dblock_free_icr(void *thing);
 
 /* Debugging Function Prototypes */
 #ifndef NDEBUG
@@ -117,35 +135,53 @@ static herr_t H5HF__cache_verify_descendant_iblocks_clean(H5F_t *f, hid_t dxpl_i
 
 /* H5HF header inherits cache-like properties from H5AC */
 const H5AC_class_t H5AC_FHEAP_HDR[1] = {{
-    H5AC_FHEAP_HDR_ID,
-    (H5AC_load_func_t)H5HF_cache_hdr_load,
-    (H5AC_flush_func_t)H5HF_cache_hdr_flush,
-    (H5AC_dest_func_t)H5HF_cache_hdr_dest,
-    (H5AC_clear_func_t)H5HF_cache_hdr_clear,
-    (H5AC_notify_func_t)NULL,
-    (H5AC_size_func_t)H5HF_cache_hdr_size,
+    H5AC_FHEAP_HDR_ID,                  /* Metadata client ID */
+    "fractal heap header",              /* Metadata client name (for debugging) */
+    H5FD_MEM_FHEAP_HDR,                 /* File space memory type for client */
+    H5AC__CLASS_SPECULATIVE_LOAD_FLAG,  /* Client class behavior flags */
+    H5HF__cache_hdr_get_load_size,      /* 'get_load_size' callback */
+    H5HF__cache_hdr_deserialize,        /* 'deserialize' callback */
+    H5HF__cache_hdr_image_len,          /* 'image_len' callback */
+    H5HF__cache_hdr_pre_serialize,      /* 'pre_serialize' callback */
+    H5HF__cache_hdr_serialize,          /* 'serialize' callback */
+    NULL,                               /* 'notify' callback */
+    H5HF__cache_hdr_free_icr,           /* 'free_icr' callback */
+    NULL,                               /* 'clear' callback */
+    NULL,                               /* 'fsf_size' callback */
 }};
 
 /* H5HF indirect block inherits cache-like properties from H5AC */
 const H5AC_class_t H5AC_FHEAP_IBLOCK[1] = {{
-    H5AC_FHEAP_IBLOCK_ID,
-    (H5AC_load_func_t)H5HF_cache_iblock_load,
-    (H5AC_flush_func_t)H5HF_cache_iblock_flush,
-    (H5AC_dest_func_t)H5HF_cache_iblock_dest,
-    (H5AC_clear_func_t)H5HF_cache_iblock_clear,
-    (H5AC_notify_func_t)H5HF_cache_iblock_notify,
-    (H5AC_size_func_t)H5HF_cache_iblock_size,
+    H5AC_FHEAP_IBLOCK_ID,               /* Metadata client ID */
+    "fractal heap indirect block",      /* Metadata client name (for debugging) */
+    H5FD_MEM_FHEAP_IBLOCK,              /* File space memory type for client */
+    H5AC__CLASS_NO_FLAGS_SET,           /* Client class behavior flags */
+    H5HF__cache_iblock_get_load_size,   /* 'get_load_size' callback */
+    H5HF__cache_iblock_deserialize,     /* 'deserialize' callback */
+    H5HF__cache_iblock_image_len,       /* 'image_len' callback */
+    H5HF__cache_iblock_pre_serialize,   /* 'pre_serialize' callback */
+    H5HF__cache_iblock_serialize,       /* 'serialize' callback */
+    H5HF__cache_iblock_notify,          /* 'notify' callback */
+    H5HF__cache_iblock_free_icr,        /* 'free_icr' callback */
+    NULL,                               /* 'clear' callback */
+    NULL,                               /* 'fsf_size' callback */
 }};
 
 /* H5HF direct block inherits cache-like properties from H5AC */
 const H5AC_class_t H5AC_FHEAP_DBLOCK[1] = {{
-    H5AC_FHEAP_DBLOCK_ID,
-    (H5AC_load_func_t)H5HF_cache_dblock_load,
-    (H5AC_flush_func_t)H5HF_cache_dblock_flush,
-    (H5AC_dest_func_t)H5HF_cache_dblock_dest,
-    (H5AC_clear_func_t)H5HF_cache_dblock_clear,
-    (H5AC_notify_func_t)H5HF_cache_dblock_notify,
-    (H5AC_size_func_t)H5HF_cache_dblock_size,
+    H5AC_FHEAP_DBLOCK_ID,               /* Metadata client ID */
+    "fractal heap direct block",        /* Metadata client name (for debugging) */
+    H5FD_MEM_FHEAP_DBLOCK,              /* File space memory type for client */
+    H5C__CLASS_COMPRESSED_FLAG,         /* Client class behavior flags */
+    H5HF__cache_dblock_get_load_size,   /* 'get_load_size' callback */
+    H5HF__cache_dblock_deserialize,     /* 'deserialize' callback */
+    H5HF__cache_dblock_image_len,       /* 'image_len' callback */
+    H5HF__cache_dblock_pre_serialize,   /* 'pre_serialize' callback */
+    H5HF__cache_dblock_serialize,       /* 'serialize' callback */
+    H5HF__cache_dblock_notify,          /* 'notify' callback */
+    H5HF__cache_dblock_free_icr,        /* 'free_icr' callback */
+    NULL,                               /* 'clear' callback */
+    NULL,                               /* 'fsf_size' callback */
 }};
 
 
@@ -268,119 +304,191 @@ H5HF__dtable_encode(H5F_t *f, uint8_t **pp, const H5HF_dtable_t *dtable)
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_hdr_load
+ * Function:	H5HF__cache_hdr_get_load_size()
  *
- * Purpose:	Loads a fractal heap header from the disk.
+ * Purpose:	Determine the size of the fractal heap header on disk,
+ *		and set *image_len to this value.
  *
- * Return:	Success:	Pointer to a new fractal heap
+ *		This code is based on the old H5HF_cache_hdr_load() routine
+ *		that was used with the version 2 metadata cache.  Note the 
+ *		use of a dummy header to compute the on disk size of the header.
+ *
+ *		Note also that the value returned by this function presumes that 
+ *		there is no I/O filtering data in the header.  If there is, the 
+ *		size reported will be too small, and H5C_load_entry()
+ *		will have to make two tries to load the fractal heap header.
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5HF__cache_hdr_get_load_size(const void *_udata, size_t *image_len)
+{
+    const H5HF_hdr_cache_ud_t *udata = (const H5HF_hdr_cache_ud_t *)_udata; /* pointer to user data */
+    H5HF_hdr_t  	dummy_hdr; 	/* dummy header -- to compute size */
+
+    FUNC_ENTER_STATIC_NOERR
+
+    /* Sanity checks */
+    HDassert(udata);
+    HDassert(image_len);
+
+    /* Set the internal parameters for the heap */
+    dummy_hdr.f = udata->f;
+    dummy_hdr.sizeof_size = H5F_SIZEOF_SIZE(udata->f);
+    dummy_hdr.sizeof_addr = H5F_SIZEOF_ADDR(udata->f);
+
+    /* Compute the 'base' size of the fractal heap header on disk */
+    *image_len = (size_t)H5HF_HEADER_SIZE(&dummy_hdr);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5HF__cache_hdr_get_load_size() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF__cache_hdr_deserialize
+ *
+ * Purpose:	Given a buffer containing an on disk image of a fractal heap
+ *		header block, allocate an instance of H5HF_hdr_t, load the contents
+ *		of the buffer into into the new instance of H5HF_hdr_t, and then
+ *		return a pointer to the new instance.
+ *
+ *		Since H5HF__cache_hdr_get_load_size() reports header on disk size 
+ *		base on the assumption that the header contains no I/O filtering 
+ *		data, it is possible that the provided image will be too small.
+ *
+ *		In this case, we DO NOT flag an error when this is discovered.
+ *		Instead, we make note of the correct image size, and report 
+ *		success.
+ *
+ *		Since H5HF__cache_hdr_image_len() callback is defined, 
+ *		H5C_load_entry() will call H5HF__cache_hdr_image_len() and 
+ *		obtain the correct image length.  
+ *
+ *		Since the H5AC__CLASS_SPECULATIVE_LOAD_FLAG is set, 
+ *		H5C_load_entry() will load an image of the correct size, and 
+ *		then call this function again to deserialize it.  Before doing 
+ *		so, it will also call H5HF__cache_hdr_free_icr() to discard the 
+ *		result of the first deserialize call.
+ *
+ *		Note that the v2 B-tree and free space manager associated 
+ *		with the fractal heap (roots stored in the huge_bt2 and fspace 
+ *		fields respectively) are not loaded at this time.  As best I can
+ *		tell from reviewing the code, they are loaded or created when 
+ *		they are accessed.
+ *
+ * Return:	Success:	Pointer to in core representation
  *		Failure:	NULL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 24 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static H5HF_hdr_t *
-H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
+static void *
+H5HF__cache_hdr_deserialize(const void *_image, size_t len, void *_udata,
+    hbool_t H5_ATTR_UNUSED *dirty)
 {
-    H5HF_hdr_t		*hdr = NULL;     /* Fractal heap info */
-    H5HF_hdr_cache_ud_t *udata = (H5HF_hdr_cache_ud_t *)_udata;
-    size_t		size;           /* Header size */
-    H5WB_t              *wb = NULL;     /* Wrapped buffer for header data */
-    uint8_t             hdr_buf[H5HF_HDR_BUF_SIZE]; /* Buffer for header */
-    uint8_t		*buf;           /* Pointer to header buffer */
-    const uint8_t	*p;             /* Pointer into raw data buffer */
+    H5HF_hdr_t          *hdr = NULL;     /* Fractal heap info */
+    H5HF_hdr_cache_ud_t *udata = (H5HF_hdr_cache_ud_t *)_udata; /* User data for callback */
+    const uint8_t       *image = (const uint8_t *)_image;       /* Pointer into into supplied image */
+    size_t              size;           /* Header size */
     uint32_t            stored_chksum;  /* Stored metadata checksum value */
     uint32_t            computed_chksum; /* Computed metadata checksum value */
     uint8_t             heap_flags;     /* Status flags for heap */
-    H5HF_hdr_t		*ret_value;     /* Return value */
+    void *              ret_value;      /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /* Check arguments */
-    HDassert(f);
-    HDassert(H5F_addr_defined(addr));
+    /* Sanity checks */
+    HDassert(image);
+    HDassert(len > 0);
     HDassert(udata);
+    HDassert(dirty);
 
     /* Allocate space for the fractal heap data structure */
     if(NULL == (hdr = H5HF_hdr_alloc(udata->f)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
-    /* Wrap the local buffer for serialized header info */
-    if(NULL == (wb = H5WB_wrap(hdr_buf, sizeof(hdr_buf))))
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, NULL, "can't wrap buffer")
-
     /* Compute the 'base' size of the fractal heap header on disk */
     size = (size_t)H5HF_HEADER_SIZE(hdr);
 
-    /* Get a pointer to a buffer that's large enough for serialized header */
-    if(NULL == (buf = (uint8_t *)H5WB_actual(wb, size)))
-        HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, NULL, "can't get actual buffer")
-
-    /* Read header from disk */
-    if(H5F_block_read(f, H5FD_MEM_FHEAP_HDR, addr, size, dxpl_id, buf) < 0)
-	HGOTO_ERROR(H5E_HEAP, H5E_READERROR, NULL, "can't read fractal heap header")
-
-    /* Get temporary pointer to serialized header */
-    p = buf;
+    /* the size we have just calculated presumes that there is no I/O 
+     * filter information in the header.  If there is no filter information,
+     * the deserialize operation should succeed.
+     *
+     * If there is filter information, the first attempt to deserialize 
+     * the header will reveal this.  In this case, we will be unable to 
+     * deserialize the header as the supplied image will be too small.
+     * However, we will make note of the correct size and report success 
+     * anyway.  
+     *
+     * When H5C_load_entry() calls H5HF__cache_hdr_image_len(), we will report 
+     * the correct size.  Since the H5C__CLASS_SPECULATIVE_LOAD_FLAG is set,
+     * this will prompt H5C_load_entry() to load the correct size image,
+     * discard the result of the first attempt at deserialization, and 
+     * call this routine a second time to deserialize the correct size 
+     * buffer.
+     */
+    HDassert(size <= len);
 
     /* Magic number */
-    if(HDmemcmp(p, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "wrong fractal heap header signature")
-    p += H5_SIZEOF_MAGIC;
+    if(HDmemcmp(image, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC))
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "wrong fractal heap header signature")
+    image += H5_SIZEOF_MAGIC;
 
     /* Version */
-    if(*p++ != H5HF_HDR_VERSION)
+    if(*image++ != H5HF_HDR_VERSION)
         HGOTO_ERROR(H5E_HEAP, H5E_VERSION, NULL, "wrong fractal heap header version")
 
     /* General heap information */
-    UINT16DECODE(p, hdr->id_len);               /* Heap ID length */
-    UINT16DECODE(p, hdr->filter_len);           /* I/O filters' encoded length */
+    UINT16DECODE(image, hdr->id_len);              /* Heap ID length */
+    UINT16DECODE(image, hdr->filter_len);          /* I/O filters' encoded length */
 
     /* Heap status flags */
     /* (bit 0: "huge" object IDs have wrapped) */
     /* (bit 1: checksum direct blocks) */
-    heap_flags = *p++;
+    heap_flags = *image++;
     hdr->huge_ids_wrapped = heap_flags & H5HF_HDR_FLAGS_HUGE_ID_WRAPPED;
     hdr->checksum_dblocks = heap_flags & H5HF_HDR_FLAGS_CHECKSUM_DBLOCKS;
 
     /* "Huge" object information */
-    UINT32DECODE(p, hdr->max_man_size);         /* Max. size of "managed" objects */
-    H5F_DECODE_LENGTH(udata->f, p, hdr->huge_next_id); /* Next ID to use for "huge" object */
-    H5F_addr_decode(udata->f, &p, &hdr->huge_bt2_addr); /* Address of "huge" object tracker B-tree */
+    UINT32DECODE(image, hdr->max_man_size);     /* Max. size of "managed" objects */
+    H5F_DECODE_LENGTH(udata->f, image, hdr->huge_next_id); /* Next ID to use for "huge" object */
+    H5F_addr_decode(udata->f, &image, &hdr->huge_bt2_addr); /* Address of "huge" object tracker B-tree */
 
     /* "Managed" object free space information */
-    H5F_DECODE_LENGTH(udata->f, p, hdr->total_man_free); /* Internal free space in managed direct blocks */
-    H5F_addr_decode(udata->f, &p, &hdr->fs_addr);      /* Address of free section header */
+    H5F_DECODE_LENGTH(udata->f, image, hdr->total_man_free); /* Internal free space in managed direct blocks */
+    H5F_addr_decode(udata->f, &image, &hdr->fs_addr);  /* Address of free section header */
 
     /* Heap statistics */
-    H5F_DECODE_LENGTH(udata->f, p, hdr->man_size);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->man_alloc_size);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->man_iter_off);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->man_nobjs);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->huge_size);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->huge_nobjs);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->tiny_size);
-    H5F_DECODE_LENGTH(udata->f, p, hdr->tiny_nobjs);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->man_size);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->man_alloc_size);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->man_iter_off);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->man_nobjs);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->huge_size);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->huge_nobjs);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->tiny_size);
+    H5F_DECODE_LENGTH(udata->f, image, hdr->tiny_nobjs);
 
     /* Managed objects' doubling-table info */
-    if(H5HF__dtable_decode(hdr->f, &p, &(hdr->man_dtable)) < 0)
+    if(H5HF__dtable_decode(hdr->f, &image, &(hdr->man_dtable)) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTENCODE, NULL, "unable to encode managed obj. doubling table info")
 
     /* Sanity check */
     /* (allow for checksum not decoded yet) */
-    HDassert((size_t)(p - (const uint8_t *)buf) == (size - H5HF_SIZEOF_CHKSUM));
+    HDassert((size_t)(image - (const uint8_t *)_image) == (size - H5HF_SIZEOF_CHKSUM));
 
     /* Check for I/O filter information to decode */
     if(hdr->filter_len > 0) {
-        size_t filter_info_off;     /* Offset in header of filter information */
         size_t filter_info_size;    /* Size of filter information */
         H5O_pline_t *pline;         /* Pipeline information from the header on disk */
 
-        /* Compute the offset of the filter info in the header */
-        filter_info_off = (size_t)(p - (const uint8_t *)buf);
-
         /* Compute the size of the extra filter information */
         filter_info_size = (size_t)(hdr->sizeof_size     /* Size of size for filtered root direct block */
             + (unsigned)4		/* Size of filter mask for filtered root direct block */
@@ -389,28 +497,27 @@ H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         /* Compute the heap header's size */
         hdr->heap_size = size + filter_info_size;
 
-        /* Re-size current buffer */
-        if(NULL == (buf = (uint8_t *)H5WB_actual(wb, hdr->heap_size)))
-            HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, NULL, "can't get actual buffer")
-
-        /* Read in I/O filter information */
-        /* (and the checksum) */
-        if(H5F_block_read(f, H5FD_MEM_FHEAP_HDR, (addr + filter_info_off), (filter_info_size + H5HF_SIZEOF_CHKSUM), dxpl_id, (buf + filter_info_off)) < 0)
-            HGOTO_ERROR(H5E_HEAP, H5E_READERROR, NULL, "can't read fractal heap header's I/O pipeline filter info")
+        if(size == len) 
+	    /* we were supplied with too small a buffer -- goto done
+             * and let H5C_load_entry() retry with a larger buffer
+             */
+	    HGOTO_DONE((void *)hdr)
 
-        /* Point at correct offset in header for the filter information */
-        p = buf + filter_info_off;
+	else
+            if((size + filter_info_size) != len)
+                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "bad image len")
 
         /* Decode the size of a filtered root direct block */
-        H5F_DECODE_LENGTH(udata->f, p, hdr->pline_root_direct_size);
+        H5F_DECODE_LENGTH(udata->f, image, hdr->pline_root_direct_size);
 
         /* Decode the filter mask for a filtered root direct block */
-        UINT32DECODE(p, hdr->pline_root_direct_filter_mask);
+        UINT32DECODE(image, hdr->pline_root_direct_filter_mask);
 
         /* Decode I/O filter information */
-        if(NULL == (pline = (H5O_pline_t *)H5O_msg_decode(hdr->f, udata->dxpl_id, NULL, H5O_PLINE_ID, p)))
+        if(NULL == (pline = (H5O_pline_t *)H5O_msg_decode(hdr->f, udata->dxpl_id, NULL, H5O_PLINE_ID, image)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTDECODE, NULL, "can't decode I/O pipeline filters")
-        p += hdr->filter_len;
+
+        image += hdr->filter_len;
 
         /* Copy the information into the header's I/O pipeline structure */
         if(NULL == H5O_msg_copy(H5O_PLINE_ID, pline, &(hdr->pline)))
@@ -425,13 +532,13 @@ H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
 
     /* Compute checksum on entire header */
     /* (including the filter information, if present) */
-    computed_chksum = H5_checksum_metadata(buf, (size_t)(p - (const uint8_t *)buf), 0);
+    computed_chksum = H5_checksum_metadata(_image, (size_t)(image - (const uint8_t *)_image), 0);
 
     /* Metadata checksum */
-    UINT32DECODE(p, stored_chksum);
+    UINT32DECODE(image, stored_chksum);
 
     /* Sanity check */
-    HDassert((size_t)(p - (const uint8_t *)buf) == hdr->heap_size);
+    HDassert((size_t)(image - (const uint8_t *)_image) == hdr->heap_size);
 
     /* Verify checksum */
     if(stored_chksum != computed_chksum)
@@ -442,291 +549,324 @@ H5HF_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         HGOTO_ERROR(H5E_RESOURCE, H5E_CANTINIT, NULL, "can't finish initializing shared fractal heap header")
 
     /* Set return value */
-    ret_value = hdr;
+    ret_value = (void *)hdr;
 
 done:
-    /* Release resources */
-    if(wb && H5WB_unwrap(wb) < 0)
-        HDONE_ERROR(H5E_HEAP, H5E_CLOSEERROR, NULL, "can't close wrapped buffer")
     if(!ret_value && hdr)
         if(H5HF_hdr_free(hdr) < 0)
             HDONE_ERROR(H5E_HEAP, H5E_CANTRELEASE, NULL, "unable to release fractal heap header")
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_hdr_load() */ /*lint !e818 Can't make udata a pointer to const */
+} /* end H5HF__cache_hdr_deserialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_hdr_flush
+ * Function:	H5HF__cache_hdr_image_len
  *
- * Purpose:	Flushes a dirty fractal heap header to disk.
+ * Purpose:	Return the actual size of the fractal heap header on 
+ *		disk image.  
  *
- * Return:	Non-negative on success/Negative on failure
+ *		If the header contains filter information, this size will be 
+ *		larger than the value returned by H5HF__cache_hdr_get_load_size().  
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 24 2006
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_hdr_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HF_hdr_t *hdr, unsigned H5_ATTR_UNUSED * flags_ptr)
+static herr_t 
+H5HF__cache_hdr_image_len(const void *_thing, size_t *image_len,
+    hbool_t H5_ATTR_UNUSED *compressed_ptr, size_t H5_ATTR_UNUSED *compressed_image_len_ptr)
 {
-    H5WB_t *wb = NULL;                  /* Wrapped buffer for header data */
-    uint8_t hdr_buf[H5HF_HDR_BUF_SIZE]; /* Buffer for header */
-    herr_t ret_value = SUCCEED;         /* Return value */
+    const H5HF_hdr_t  *hdr = (const H5HF_hdr_t *)_thing;    /* Fractal heap info */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC_NOERR
 
-    /* check arguments */
-    HDassert(f);
-    HDassert(H5F_addr_defined(addr));
+    /* Sanity checks */
     HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
+    HDassert(image_len);
 
-    if(hdr->cache_info.is_dirty) {
-        uint8_t	*buf;           /* Temporary raw data buffer */
-        uint8_t *p;             /* Pointer into raw data buffer */
-        size_t	size;           /* Header size on disk */
-        uint8_t heap_flags;     /* Status flags for heap */
-        uint32_t metadata_chksum; /* Computed metadata checksum value */
-
-#ifndef NDEBUG
-{
-        /* Verify that flush dependencies are working correctly.  Do this
-	 * by verifying that either:
-         *
-         * 1) the header has a root iblock, and that the root iblock and all
- 	 *    of its children are clean, or
-         *
-         * 2) The header has a root dblock, which is clean, or
-         *
-         * 3) The heap is empty, and thus the header has neither a root
-         *    iblock no a root dblock.  In this case, the flush ordering
-         *    constraint is met by default.
-	 *
- 	 * Do this with a call to H5HF__cache_verify_hdr_descendants_clean().
-	 */
-	hbool_t descendants_clean = TRUE;
+    *image_len = hdr->heap_size;
 
-	if(H5HF__cache_verify_hdr_descendants_clean(f, dxpl_id, hdr, &descendants_clean) < 0)
-	     HGOTO_ERROR(H5E_HEAP, H5E_SYSTEM, FAIL, "can't verify hdr descendants clean.")
-	HDassert(descendants_clean);
-}
-#endif /* NDEBUG */
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5HF__cache_hdr_image_len() */
 
-        /* Set the shared heap header's file context for this operation */
-        hdr->f = f;
-
-        /* Wrap the local buffer for serialized header info */
-        if(NULL == (wb = H5WB_wrap(hdr_buf, sizeof(hdr_buf))))
-            HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't wrap buffer")
-
-        /* Compute the size of the heap header on disk */
-        size = hdr->heap_size;
-
-        /* Get a pointer to a buffer that's large enough for serialized header */
-        if(NULL == (buf = (uint8_t *)H5WB_actual(wb, size)))
-            HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "can't get actual buffer")
-
-        /* Get temporary pointer to serialized header */
-        p = buf;
-
-        /* Magic number */
-        HDmemcpy(p, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC);
-        p += H5_SIZEOF_MAGIC;
-
-        /* Version # */
-        *p++ = H5HF_HDR_VERSION;
-
-        /* General heap information */
-        UINT16ENCODE(p, hdr->id_len);           /* Heap ID length */
-        UINT16ENCODE(p, hdr->filter_len);       /* I/O filters' encoded length */
-
-        /* Heap status flags */
-        /* (bit 0: "huge" object IDs have wrapped) */
-        /* (bit 1: checksum direct blocks) */
-        heap_flags = 0;
-        heap_flags = (uint8_t)(heap_flags | (hdr->huge_ids_wrapped ? H5HF_HDR_FLAGS_HUGE_ID_WRAPPED : 0));
-        heap_flags = (uint8_t)(heap_flags | (hdr->checksum_dblocks ? H5HF_HDR_FLAGS_CHECKSUM_DBLOCKS : 0));
-        *p++ = heap_flags;
-
-        /* "Huge" object information */
-        UINT32ENCODE(p, hdr->max_man_size);             /* Max. size of "managed" objects */
-        H5F_ENCODE_LENGTH(f, p, hdr->huge_next_id);     /* Next ID to use for "huge" object */
-        H5F_addr_encode(f, &p, hdr->huge_bt2_addr);     /* Address of "huge" object tracker B-tree */
-
-        /* "Managed" object free space information */
-        H5F_ENCODE_LENGTH(f, p, hdr->total_man_free);   /* Internal free space in managed direct blocks */
-        H5F_addr_encode(f, &p, hdr->fs_addr);           /* Address of free section header */
-
-        /* Heap statistics */
-        H5F_ENCODE_LENGTH(f, p, hdr->man_size);
-        H5F_ENCODE_LENGTH(f, p, hdr->man_alloc_size);
-        H5F_ENCODE_LENGTH(f, p, hdr->man_iter_off);
-        H5F_ENCODE_LENGTH(f, p, hdr->man_nobjs);
-        H5F_ENCODE_LENGTH(f, p, hdr->huge_size);
-        H5F_ENCODE_LENGTH(f, p, hdr->huge_nobjs);
-        H5F_ENCODE_LENGTH(f, p, hdr->tiny_size);
-        H5F_ENCODE_LENGTH(f, p, hdr->tiny_nobjs);
-
-        /* Managed objects' doubling-table info */
-        if(H5HF__dtable_encode(hdr->f, &p, &(hdr->man_dtable)) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTENCODE, FAIL, "unable to encode managed obj. doubling table info")
-
-        /* Check for I/O filter information to encode */
-        if(hdr->filter_len > 0) {
-            /* Encode the size of a filtered root direct block */
-            H5F_ENCODE_LENGTH(f, p, hdr->pline_root_direct_size);
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF__cache_hdr_pre_serialize
+ *
+ * Purpose:	As best I can tell, fractal heap header blocks are always 
+ *		allocated in real file space.  Thus this routine simply verifies
+ *		this, verifies that the len parameter contains the expected
+ *		value, and returns an error if either of these checks fail.
+ *
+ *		When compiled in debug mode, the function also verifies that all
+ *		indirect and direct blocks that are children of the header are 
+ *		either clean, or not in the metadata cache.
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5HF__cache_hdr_pre_serialize(const H5F_t *f, hid_t dxpl_id, void *_thing,
+    haddr_t addr, size_t len, size_t H5_ATTR_UNUSED compressed_len, 
+    haddr_t H5_ATTR_UNUSED *new_addr, size_t H5_ATTR_UNUSED *new_len,
+    size_t H5_ATTR_UNUSED *new_compressed_len, unsigned *flags)
+{
+    H5HF_hdr_t *hdr = (H5HF_hdr_t *)_thing;     /* Fractal heap info */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
-            /* Encode the filter mask for a filtered root direct block */
-            UINT32ENCODE(p, hdr->pline_root_direct_filter_mask);
+    FUNC_ENTER_STATIC
 
-            /* Encode I/O filter information */
-            if(H5O_msg_encode(hdr->f, H5O_PLINE_ID, FALSE, p, &(hdr->pline)) < 0)
-                HGOTO_ERROR(H5E_HEAP, H5E_CANTENCODE, FAIL, "can't encode I/O pipeline fiters")
-            p += hdr->filter_len;
-        } /* end if */
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
+    HDassert(H5F_addr_defined(addr));
+    HDassert(addr == hdr->heap_addr);
+    HDassert(new_addr);
+    HDassert(new_len);
+    HDassert(flags);
 
-        /* Compute metadata checksum */
-        metadata_chksum = H5_checksum_metadata(buf, (size_t)(p - buf), 0);
+#ifndef NDEBUG
+{
+    hbool_t descendants_clean = TRUE;
 
-        /* Metadata checksum */
-        UINT32ENCODE(p, metadata_chksum);
+    /* Verify that flush dependencies are working correctly.  Do this
+     * by verifying that either:
+     *
+     * 1) the header has a root iblock, and that the root iblock and all
+     *    of its children are clean, or
+     *
+     * 2) The header has a root dblock, which is clean, or
+     *
+     * 3) The heap is empty, and thus the header has neither a root
+     *    iblock no a root dblock.  In this case, the flush ordering
+     *    constraint is met by default.
+     *
+     * Do this with a call to H5HF__cache_verify_hdr_descendants_clean().
+     */
+    if(H5HF__cache_verify_hdr_descendants_clean((H5F_t *)f, dxpl_id, hdr, &descendants_clean) < 0)
+         HGOTO_ERROR(H5E_HEAP, H5E_SYSTEM, FAIL, "can't verify hdr descendants clean.")
+    HDassert(descendants_clean);
+}
+#endif /* NDEBUG */
 
-	/* Write the heap header. */
-        HDassert((size_t)(p - buf) == size);
-	if(H5F_block_write(f, H5FD_MEM_FHEAP_HDR, addr, size, dxpl_id, buf) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFLUSH, FAIL, "unable to save fractal heap header to disk")
+    if(H5F_IS_TMP_ADDR(f, addr))
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "addr in temporary space?!?.");
 
-	hdr->cache_info.is_dirty = FALSE;
-    } /* end if */
+    if(len != hdr->heap_size)
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, FAIL, "unexpected image len.");
 
-    if(destroy)
-        if(H5HF_cache_hdr_dest(f, hdr) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap header")
+    *flags = 0;
 
 done:
-    /* Release resources */
-    if(wb && H5WB_unwrap(wb) < 0)
-        HDONE_ERROR(H5E_HEAP, H5E_CLOSEERROR, FAIL, "can't close wrapped buffer")
-
     FUNC_LEAVE_NOAPI(ret_value)
-} /* H5HF_cache_hdr_flush() */
+} /* end H5HF__cache_hdr_pre_serialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_hdr_dest
+ * Function:	H5HF__cache_hdr_serialize
  *
- * Purpose:	Destroys a fractal heap header in memory.
+ * Purpose:	Construct the on disk image of the header, and place it in 
+ *		the buffer pointed to by image.  Return SUCCEED on success,
+ *		and FAIL on failure.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 24 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_hdr_dest(H5F_t *f, H5HF_hdr_t *hdr)
+static herr_t 
+H5HF__cache_hdr_serialize(const H5F_t *f, void *_image, size_t len,
+    void *_thing)
 {
+    H5HF_hdr_t *hdr = (H5HF_hdr_t *)_thing;     /* Fractal heap info */
+    uint8_t    *image = (uint8_t *)_image;      /* Pointer into raw data buffer */
+    uint8_t 	heap_flags;             /* Status flags for heap */
+    uint32_t 	metadata_chksum;        /* Computed metadata checksum value */
     herr_t      ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(image);
     HDassert(hdr);
-    HDassert(hdr->rc == 0);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
+    HDassert(len == hdr->heap_size);
 
-    /* If we're going to free the space on disk, the address must be valid */
-    HDassert(!hdr->cache_info.free_file_space_on_destroy || H5F_addr_defined(hdr->cache_info.addr));
+    /* Set the shared heap header's file context for this operation */
+    hdr->f = f;
+
+    /* Magic number */
+    HDmemcpy(image, H5HF_HDR_MAGIC, (size_t)H5_SIZEOF_MAGIC);
+    image += H5_SIZEOF_MAGIC;
 
-    /* Check for freeing file space for heap header */
-    if(hdr->cache_info.free_file_space_on_destroy) {
-        /* Release the space on disk */
-        /* (XXX: Nasty usage of internal DXPL value! -QAK) */
-        if(H5MF_xfree(f, H5FD_MEM_FHEAP_HDR, H5AC_dxpl_id, hdr->cache_info.addr, (hsize_t)hdr->heap_size) < 0)
-            HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap header")
+    /* Version # */
+    *image++ = H5HF_HDR_VERSION;
+
+    /* General heap information */
+    UINT16ENCODE(image, hdr->id_len);           /* Heap ID length */
+    UINT16ENCODE(image, hdr->filter_len);       /* I/O filters' encoded length */
+
+    /* Heap status flags */
+    /* (bit 0: "huge" object IDs have wrapped) */
+    /* (bit 1: checksum direct blocks) */
+    heap_flags = 0;
+    heap_flags = (uint8_t)(heap_flags | (hdr->huge_ids_wrapped ? H5HF_HDR_FLAGS_HUGE_ID_WRAPPED : 0));
+    heap_flags = (uint8_t)(heap_flags | (hdr->checksum_dblocks ? H5HF_HDR_FLAGS_CHECKSUM_DBLOCKS : 0));
+    *image++ = heap_flags;
+
+    /* "Huge" object information */
+    UINT32ENCODE(image, hdr->max_man_size);   /* Max. size of "managed" objects */
+    H5F_ENCODE_LENGTH(f, image, hdr->huge_next_id); /* Next ID to use for "huge" object */
+    H5F_addr_encode(f, &image, hdr->huge_bt2_addr); /* Address of "huge" object tracker B-tree */
+
+    /* "Managed" object free space information */
+    H5F_ENCODE_LENGTH(f, image, hdr->total_man_free); /* Internal free space in managed direct blocks */
+    H5F_addr_encode(f, &image, hdr->fs_addr); /* Address of free section header */
+
+    /* Heap statistics */
+    H5F_ENCODE_LENGTH(f, image, hdr->man_size);
+    H5F_ENCODE_LENGTH(f, image, hdr->man_alloc_size);
+    H5F_ENCODE_LENGTH(f, image, hdr->man_iter_off);
+    H5F_ENCODE_LENGTH(f, image, hdr->man_nobjs);
+    H5F_ENCODE_LENGTH(f, image, hdr->huge_size);
+    H5F_ENCODE_LENGTH(f, image, hdr->huge_nobjs);
+    H5F_ENCODE_LENGTH(f, image, hdr->tiny_size);
+    H5F_ENCODE_LENGTH(f, image, hdr->tiny_nobjs);
+
+    /* Managed objects' doubling-table info */
+    if(H5HF__dtable_encode(hdr->f, &image, &(hdr->man_dtable)) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTENCODE, FAIL, "unable to encode managed obj. doubling table info")
+
+    /* Check for I/O filter information to encode */
+    if(hdr->filter_len > 0) {
+        /* Encode the size of a filtered root direct block */
+        H5F_ENCODE_LENGTH(f, image, hdr->pline_root_direct_size);
+
+        /* Encode the filter mask for a filtered root direct block */
+        UINT32ENCODE(image, hdr->pline_root_direct_filter_mask);
+
+        /* Encode I/O filter information */
+        if(H5O_msg_encode(hdr->f, H5O_PLINE_ID, FALSE, image, &(hdr->pline)) < 0)
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTENCODE, FAIL, "can't encode I/O pipeline fiters")
+        image += hdr->filter_len;
     } /* end if */
 
-    /* Free the shared info itself */
-    if(H5HF_hdr_free(hdr) < 0)
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTRELEASE, FAIL, "unable to release fractal heap header")
+    /* Compute metadata checksum */
+    metadata_chksum = H5_checksum_metadata(_image, (size_t)(image - (uint8_t *)_image), 0);
+
+    /* Metadata checksum */
+    UINT32ENCODE(image, metadata_chksum);
+
+    /* sanity check */
+    HDassert((size_t)(image - (uint8_t *)_image) == len);
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_hdr_dest() */
+} /* end H5HF__cache_hdr_serialize() */
+
+/***************************************/
+/* no H5HF__cache_hdr_notify() function */
+/***************************************/
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_hdr_clear
+ * Function:	H5HF__cache_hdr_free_icr
  *
- * Purpose:	Mark a fractal heap header in memory as non-dirty.
+ * Purpose:	Free the in core representation of the fractal heap header.
  *
- * Return:	Non-negative on success/Negative on failure
+ *		This routine frees just the header itself, not the 
+ *		associated version 2 B-Tree, the associated Free Space Manager,
+ *		nor the indirect/direct block tree that is rooted in the header.
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 24 2006
+ *		This routine also does not free the file space that may
+ *		be allocated to the header.
+ *
+ * Note:	The metadata cache sets the object's cache_info.magic to
+ *		H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC before calling a free_icr
+ *		callback (checked in assert).
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_hdr_clear(H5F_t *f, H5HF_hdr_t *hdr, hbool_t destroy)
+static herr_t 
+H5HF__cache_hdr_free_icr(void *_thing)
 {
-    herr_t ret_value = SUCCEED;         /* Return value */
+    H5HF_hdr_t *hdr = (H5HF_hdr_t *)_thing;     /* Fractal heap info */
+    herr_t      ret_value = SUCCEED;            /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
     HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
+    HDassert(hdr->rc == 0);
 
-    /* Reset the dirty flag.  */
-    hdr->cache_info.is_dirty = FALSE;
-
-    if(destroy)
-        if(H5HF_cache_hdr_dest(f, hdr) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap header")
+    if(H5HF_hdr_free(hdr) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTRELEASE, FAIL, "unable to release fractal heap header")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_hdr_clear() */
+} /* end H5HF__cache_hdr_free_icr() */
+
+/***********************************************************/
+/* metadata cache callback definitions for indirect blocks */
+/***********************************************************/
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_hdr_size
+ * Function:	H5HF__cache_iblock_get_load_size()
  *
- * Purpose:	Compute the size in bytes of a fractal heap header
- *		on disk, and return it in *size_ptr.  On failure,
- *		the value of *size_ptr is undefined.
+ * Purpose:	Compute the size of the on disk image of the indirect 
+ *		block, and place this value in *image_len.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 24 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_hdr_size(const H5F_t H5_ATTR_UNUSED *f, const H5HF_hdr_t *hdr, size_t *size_ptr)
+static herr_t 
+H5HF__cache_iblock_get_load_size(const void *_udata, size_t *image_len)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    const H5HF_iblock_cache_ud_t *udata = (const H5HF_iblock_cache_ud_t *)_udata;   /* User data for callback */
 
-    /* Check arguments */
-    HDassert(f);
-    HDassert(hdr);
-    HDassert(size_ptr);
+    FUNC_ENTER_STATIC_NOERR
 
-    /* Set size value */
-    *size_ptr = hdr->heap_size;
+    /* Sanity checks */
+    HDassert(udata);
+    HDassert(image_len);
+   
+    *image_len = (size_t)H5HF_MAN_INDIRECT_SIZE(udata->par_info->hdr, *udata->nrows);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_cache_hdr_size() */
+} /* end H5HF__cache_iblock_get_load_size() */
 
 /***********************************************************/
 /* metadata cache callback definitions for indirect blocks */
@@ -734,53 +874,55 @@ H5HF_cache_hdr_size(const H5F_t H5_ATTR_UNUSED *f, const H5HF_hdr_t *hdr, size_t
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_iblock_load
+ * Function:	H5HF__cache_iblock_deserialize
  *
- * Purpose:	Loads a fractal heap indirect block from the disk.
+ * Purpose:	Given a buffer containing the on disk image of the indirect 
+ *		block, allocate an instance of H5HF_indirect_t, load the data 
+ *		in the buffer into this new instance, and return a pointer to 
+ *		it.
  *
- * Return:	Success:	Pointer to a new fractal heap indirect block
+ *		As best I can tell, the size of the indirect block image is fully
+ *		know before the image is loaded, so this function should succeed
+ *		unless the image is corrupt or memory allocation fails.
  *
+ * Return:	Success:	Pointer to in core representation
  *		Failure:	NULL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 27 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static H5HF_indirect_t *
-H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
+static void *
+H5HF__cache_iblock_deserialize(const void *_image, size_t len, void *_udata,
+    hbool_t H5_ATTR_UNUSED *dirty)
 {
     H5HF_hdr_t          *hdr;           /* Shared fractal heap information */
-    H5HF_iblock_cache_ud_t *udata = (H5HF_iblock_cache_ud_t *)_udata; /* user data for callback */
-    H5HF_indirect_t	*iblock = NULL; /* Indirect block info */
-    H5WB_t              *wb = NULL;     /* Wrapped buffer for indirect block data */
-    uint8_t             iblock_buf[H5HF_IBLOCK_BUF_SIZE]; /* Buffer for indirect block */
-    uint8_t		*buf;           /* Temporary buffer */
-    const uint8_t	*p;             /* Pointer into raw data buffer */
+    H5HF_iblock_cache_ud_t *udata = (H5HF_iblock_cache_ud_t *)_udata; /* User data for callback */
+    H5HF_indirect_t     *iblock = NULL; /* Indirect block info */
+    const uint8_t       *image = (const uint8_t *)_image;       /* Pointer into raw data buffer */
     haddr_t             heap_addr;      /* Address of heap header in the file */
     uint32_t            stored_chksum;  /* Stored metadata checksum value */
     uint32_t            computed_chksum; /* Computed metadata checksum value */
     unsigned            u;              /* Local index variable */
-    H5HF_indirect_t	*ret_value;     /* Return value */
+    void *              ret_value;      /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /* Check arguments */
-    HDassert(f);
-    HDassert(H5F_addr_defined(addr));
+    /* Sanity checks */
+    HDassert(image);
     HDassert(udata);
-
-    /* Allocate space for the fractal heap indirect block */
-    if(NULL == (iblock = H5FL_CALLOC(H5HF_indirect_t)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
-
-    /* Get the pointer to the shared heap header */
+    HDassert(dirty);
     hdr = udata->par_info->hdr;
+    HDassert(hdr->f);
 
     /* Set the shared heap header's file context for this operation */
     hdr->f = udata->f;
 
+    /* Allocate space for the fractal heap indirect block */
+    if(NULL == (iblock = H5FL_CALLOC(H5HF_indirect_t)))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
+
     /* Share common heap information */
     iblock->hdr = hdr;
     if(H5HF_hdr_incr(hdr) < 0)
@@ -791,35 +933,23 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
     iblock->nrows = *udata->nrows;
     iblock->nchildren = 0;
 
-    /* Wrap the local buffer for serialized indirect block */
-    if(NULL == (wb = H5WB_wrap(iblock_buf, sizeof(iblock_buf))))
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, NULL, "can't wrap buffer")
-
     /* Compute size of indirect block */
     iblock->size = H5HF_MAN_INDIRECT_SIZE(hdr, iblock->nrows);
 
-    /* Get a pointer to a buffer that's large enough for serialized indirect block */
-    if(NULL == (buf = (uint8_t *)H5WB_actual(wb, iblock->size)))
-        HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, NULL, "can't get actual buffer")
-
-    /* Read indirect block from disk */
-    if(H5F_block_read(f, H5FD_MEM_FHEAP_IBLOCK, addr, iblock->size, dxpl_id, buf) < 0)
-	HGOTO_ERROR(H5E_HEAP, H5E_READERROR, NULL, "can't read fractal heap indirect block")
-
-    /* Get temporary pointer to serialized indirect block */
-    p = buf;
+    /* sanity check */
+    HDassert(iblock->size == len);
 
     /* Magic number */
-    if(HDmemcmp(p, H5HF_IBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "wrong fractal heap indirect block signature")
-    p += H5_SIZEOF_MAGIC;
+    if(HDmemcmp(image, H5HF_IBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC))
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "wrong fractal heap indirect block signature")
+    image += H5_SIZEOF_MAGIC;
 
     /* Version */
-    if(*p++ != H5HF_IBLOCK_VERSION)
+    if(*image++ != H5HF_IBLOCK_VERSION)
         HGOTO_ERROR(H5E_HEAP, H5E_VERSION, NULL, "wrong fractal heap direct block version")
 
     /* Address of heap that owns this block */
-    H5F_addr_decode(udata->f, &p, &heap_addr);
+    H5F_addr_decode(udata->f, &image, &heap_addr);
     if(H5F_addr_ne(heap_addr, hdr->heap_addr))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "incorrect heap header address for direct block")
 
@@ -844,7 +974,7 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
     } /* end else */
 
     /* Offset of heap within the heap's address space */
-    UINT64DECODE_VAR(p, iblock->block_off, hdr->heap_off_size);
+    UINT64DECODE_VAR(image, iblock->block_off, hdr->heap_off_size);
 
     /* Allocate & decode child block entry tables */
     HDassert(iblock->nrows > 0);
@@ -866,7 +996,7 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
 
     for(u = 0; u < (iblock->nrows * hdr->man_dtable.cparam.width); u++) {
         /* Decode child block address */
-        H5F_addr_decode(udata->f, &p, &(iblock->ents[u].addr));
+        H5F_addr_decode(udata->f, &image, &(iblock->ents[u].addr));
 
         /* Check for heap with I/O filters */
         if(hdr->filter_len > 0) {
@@ -876,7 +1006,7 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
             /* Decode extra information for direct blocks */
             if(u < (hdr->man_dtable.max_direct_rows * hdr->man_dtable.cparam.width)) {
                 /* Size of filtered direct block */
-                H5F_DECODE_LENGTH(udata->f, p, iblock->filt_ents[u].size);
+                H5F_DECODE_LENGTH(udata->f, image, iblock->filt_ents[u].size);
 
                 /* Sanity check */
                 /* (either both the address & size are defined or both are
@@ -886,7 +1016,7 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
                     || (!H5F_addr_defined(iblock->ents[u].addr) && iblock->filt_ents[u].size == 0));
 
                 /* I/O filter mask for filtered direct block */
-                UINT32DECODE(p, iblock->filt_ents[u].filter_mask);
+                UINT32DECODE(image, iblock->filt_ents[u].filter_mask);
             } /* end if */
         } /* end if */
 
@@ -901,13 +1031,13 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
     HDassert(iblock->nchildren);   /* indirect blocks w/no children should have been deleted */
 
     /* Compute checksum on indirect block */
-    computed_chksum = H5_checksum_metadata(buf, (size_t)(p - (const uint8_t *)buf), 0);
+    computed_chksum = H5_checksum_metadata((const uint8_t *)_image, (size_t)(image - (const uint8_t *)_image), 0);
 
     /* Metadata checksum */
-    UINT32DECODE(p, stored_chksum);
+    UINT32DECODE(image, stored_chksum);
 
     /* Sanity check */
-    HDassert((size_t)(p - (const uint8_t *)buf) == iblock->size);
+    HDassert((size_t)(image - (const uint8_t *)_image) == iblock->size);
 
     /* Verify checksum */
     if(stored_chksum != computed_chksum)
@@ -915,7 +1045,7 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
 
     /* Check if we have any indirect block children */
     if(iblock->nrows > hdr->man_dtable.max_direct_rows) {
-        unsigned indir_rows;      /* Number of indirect rows in this indirect block */
+        unsigned indir_rows;/* Number of indirect rows in this indirect block */
 
         /* Compute the number of indirect rows for this indirect block */
         indir_rows = iblock->nrows - hdr->man_dtable.max_direct_rows;
@@ -928,343 +1058,323 @@ H5HF_cache_iblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         iblock->child_iblocks = NULL;
 
     /* Set return value */
-    ret_value = iblock;
+    ret_value = (void *)iblock;
 
 done:
-    /* Release resources */
-    if(wb && H5WB_unwrap(wb) < 0)
-        HDONE_ERROR(H5E_HEAP, H5E_CLOSEERROR, NULL, "can't close wrapped buffer")
     if(!ret_value && iblock)
         if(H5HF_man_iblock_dest(iblock) < 0)
             HDONE_ERROR(H5E_HEAP, H5E_CANTFREE, NULL, "unable to destroy fractal heap indirect block")
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_iblock_load() */
+} /* end H5HF__cache_iblock_deserialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_iblock_flush
+ * Function:	H5HF__cache_iblock_image_len
  *
- * Purpose:	Flushes a dirty fractal heap indirect block to disk.
+ * Purpose:	Return the size of the on disk image of the iblock.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Mar  6 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_iblock_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HF_indirect_t *iblock, unsigned H5_ATTR_UNUSED * flags_ptr)
+static herr_t 
+H5HF__cache_iblock_image_len(const void *_thing, size_t *image_len,
+    hbool_t H5_ATTR_UNUSED *compressed_ptr, size_t H5_ATTR_UNUSED *compressed_image_len_ptr)
 {
-    H5WB_t      *wb = NULL;             /* Wrapped buffer for indirect block data */
-    uint8_t     iblock_buf[H5HF_IBLOCK_BUF_SIZE]; /* Buffer for indirect block */
-    herr_t      ret_value = SUCCEED;    /* Return value */
+    const H5HF_indirect_t *iblock = (const H5HF_indirect_t *)_thing;    /* Indirect block info */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC_NOERR
 
-    /* check arguments */
-    HDassert(f);
-    HDassert(H5F_addr_defined(addr));
+    /* Sanity checks */
     HDassert(iblock);
+    HDassert(iblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(iblock->cache_info.type == H5AC_FHEAP_IBLOCK);
+    HDassert(image_len);
 
-    if(iblock->cache_info.is_dirty) {
-        H5HF_hdr_t *hdr;                /* Shared fractal heap information */
-        uint8_t	*buf;                   /* Temporary buffer */
-        uint8_t *p;                     /* Pointer into raw data buffer */
-#ifndef NDEBUG
-        unsigned nchildren = 0;         /* Track # of children */
-        unsigned max_child = 0;         /* Track max. child entry used */
-#endif /* NDEBUG */
-        uint32_t metadata_chksum;       /* Computed metadata checksum value */
-        size_t u;                       /* Local index variable */
-
-#ifndef NDEBUG
-{
-        /* Verify that flush dependencies are working correctly.  Do this 
-	 * by verifying that all children of this iblock are clean.
-	 */
-	hbool_t descendants_clean = TRUE;
-	unsigned iblock_status;
-
-        if(H5AC_get_entry_status(f, iblock->addr, &iblock_status) < 0)
-            HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "can't get iblock status")
-
-	/* since the current iblock is the guest of honor in a flush, we know
-         * that it is locked into the cache for the duration of the call.  Hence
-         * there is no need to check to see if it is pinned or protected, or to
-         * protect it if it is not.
-         */
-	if(H5HF__cache_verify_iblock_descendants_clean(f, dxpl_id, iblock, &iblock_status, &descendants_clean) < 0)
-	     HGOTO_ERROR(H5E_HEAP, H5E_SYSTEM, FAIL, "can't verify descendants clean.")
-
-	HDassert(descendants_clean);
-}
-#endif /* NDEBUG */
-
-        /* Get the pointer to the shared heap header */
-        hdr = iblock->hdr;
-
-        /* Set the shared heap header's file context for this operation */
-        hdr->f = f;
-
-        /* Wrap the local buffer for serialized indirect block */
-        if(NULL == (wb = H5WB_wrap(iblock_buf, sizeof(iblock_buf))))
-            HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "can't wrap buffer")
-
-        /* Get a pointer to a buffer that's large enough for serialized indirect block */
-        if(NULL == (buf = (uint8_t *)H5WB_actual(wb, iblock->size)))
-            HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "can't get actual buffer")
-
-        /* Get temporary pointer to buffer for serialized indirect block */
-        p = buf;
-
-        /* Magic number */
-        HDmemcpy(p, H5HF_IBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC);
-        p += H5_SIZEOF_MAGIC;
-
-        /* Version # */
-        *p++ = H5HF_IBLOCK_VERSION;
-
-        /* Address of heap header for heap which owns this block */
-        H5F_addr_encode(f, &p, hdr->heap_addr);
-
-        /* Offset of block in heap */
-        UINT64ENCODE_VAR(p, iblock->block_off, hdr->heap_off_size);
-
-        /* Encode indirect block-specific fields */
-        for(u = 0; u < (iblock->nrows * hdr->man_dtable.cparam.width); u++) {
-            /* Encode child block address */
-            H5F_addr_encode(f, &p, iblock->ents[u].addr);
+    *image_len = iblock->size;
 
-            /* Check for heap with I/O filters */
-            if(hdr->filter_len > 0) {
-                /* Sanity check */
-                HDassert(iblock->filt_ents);
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5HF__cache_iblock_image_len() */
 
-                /* Encode extra information for direct blocks */
-                if(u < (hdr->man_dtable.max_direct_rows * hdr->man_dtable.cparam.width)) {
-                    /* Sanity check */
-                    /* (either both the address & size are defined or both are
-                     *  not defined)
-                     */
-                    HDassert((H5F_addr_defined(iblock->ents[u].addr) && iblock->filt_ents[u].size)
-                        || (!H5F_addr_defined(iblock->ents[u].addr) && iblock->filt_ents[u].size == 0));
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF__cache_iblock_pre_serialize
+ *
+ * Purpose:	The primary objective of this function is to determine if the
+ *		indirect block is currently allocated in temporary file space,
+ *		and if so, to move it to real file space before the entry is 
+ *		serialized.
+ *
+ *		In debug compiles, this function also verifies that all children
+ *		of this indirect block are either clean or are not in cache.
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5HF__cache_iblock_pre_serialize(const H5F_t *f, hid_t dxpl_id, void *_thing,
+    haddr_t addr, size_t H5_ATTR_UNUSED len, size_t H5_ATTR_UNUSED compressed_len,
+    haddr_t *new_addr, size_t H5_ATTR_UNUSED *new_len,
+    size_t H5_ATTR_UNUSED *new_compressed_len, unsigned *flags)
+{
+    H5HF_hdr_t          *hdr;                   /* Shared fractal heap information */
+    H5HF_indirect_t     *iblock = (H5HF_indirect_t *)_thing;    /* Indirect block info */
+    herr_t      	 ret_value = SUCCEED;    /* Return value */
 
-                    /* Size of filtered direct block */
-                    H5F_ENCODE_LENGTH(f, p, iblock->filt_ents[u].size);
+    FUNC_ENTER_STATIC
 
-                    /* I/O filter mask for filtered direct block */
-                    UINT32ENCODE(p, iblock->filt_ents[u].filter_mask);
-                } /* end if */
-            } /* end if */
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(iblock);
+    HDassert(iblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(iblock->cache_info.type == H5AC_FHEAP_IBLOCK);
+    HDassert(iblock->cache_info.size == iblock->size);
+    HDassert(H5F_addr_defined(addr));
+    HDassert(H5F_addr_eq(iblock->addr, addr));
+    HDassert(new_addr);
+    HDassert(new_len);
+    HDassert(flags);
+    hdr = iblock->hdr;
+    HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
 
 #ifndef NDEBUG
-            /* Count child blocks */
-            if(H5F_addr_defined(iblock->ents[u].addr)) {
-                nchildren++;
-                if(u > max_child)
-                    max_child = u;
-            } /* end if */
-#endif /* NDEBUG */
-        } /* end for */
-
-        /* Compute checksum */
-        metadata_chksum = H5_checksum_metadata(buf, (size_t)(p - buf), 0);
+{
+    hbool_t 		 descendants_clean = TRUE;
+    unsigned 		 iblock_status = 0;
 
-        /* Metadata checksum */
-        UINT32ENCODE(p, metadata_chksum);
+    /* verify that flush dependencies are working correctly.  Do this
+     * by verifying that all children of this iblock are clean.
+     */
+    if(H5AC_get_entry_status(f, iblock->addr, &iblock_status) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTGET, FAIL, "can't get iblock status")
 
-        /* Sanity check */
-        HDassert((size_t)(p - buf) == iblock->size);
-#ifndef NDEBUG
-        HDassert(nchildren == iblock->nchildren);
-        HDassert(max_child == iblock->max_child);
+    /* since the current iblock is the guest of honor in a flush, we know
+     * that it is locked into the cache for the duration of the call.  Hence
+     * there is no need to check to see if it is pinned or protected, or to
+     * protect it if it is not.
+     */
+    if(H5HF__cache_verify_iblock_descendants_clean((H5F_t *)f, dxpl_id, iblock, &iblock_status, &descendants_clean) < 0)
+         HGOTO_ERROR(H5E_HEAP, H5E_SYSTEM, FAIL, "can't verify descendants clean.")
+    HDassert(descendants_clean);
+}
 #endif /* NDEBUG */
 
-        /* Check for needing to re-allocate indirect block from 'temp.' to 'normal' file space */
-        if(H5F_IS_TMP_ADDR(f, addr)) {
-            /* Sanity check */
-            HDassert(H5F_addr_eq(iblock->addr, addr));
+    /* Check to see if we must re-allocate the iblock from temporary to 
+     * normal (AKA real) file space.
+     */
+    if(H5F_IS_TMP_ADDR(f, addr)) {
+        haddr_t iblock_addr;
 
-            /* Allocate 'normal' space for the new indirect block on disk */
-            if(HADDR_UNDEF == (addr = H5MF_alloc(f, H5FD_MEM_FHEAP_IBLOCK, dxpl_id, (hsize_t)iblock->size)))
-                HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap indirect block")
+        /* Allocate 'normal' space for the new indirect block on disk */
+        if(HADDR_UNDEF == (iblock_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FHEAP_IBLOCK, dxpl_id, (hsize_t)iblock->size)))
+            HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap indirect block")
 
-            /* Sanity check */
-            HDassert(!H5F_addr_eq(iblock->addr, addr));
+        /* Sanity check */
+        HDassert(!H5F_addr_eq(iblock->addr, iblock_addr));
 
-            /* Let the metadata cache know the block moved */
-            if(H5AC_move_entry(f, H5AC_FHEAP_IBLOCK, iblock->addr, addr) < 0)
-                HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move indirect block")
+        /* Let the metadata cache know the block moved */
+        if(H5AC_move_entry((H5F_t *)f, H5AC_FHEAP_IBLOCK, iblock->addr, iblock_addr) < 0)
+            HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move indirect block")
 
-            /* Update the internal address for the block */
-            iblock->addr = addr;
+        /* Update the internal address for the block */
+        iblock->addr = iblock_addr;
 
-            /* Check for root indirect block */
-            if(NULL == iblock->parent) {
-                /* Update information about indirect block's location */
-                hdr->man_dtable.table_addr = addr;
+        /* Check for root indirect block */
+        if(NULL == iblock->parent) {
+            /* Update information about indirect block's location */
+            hdr->man_dtable.table_addr = iblock_addr;
 
-                /* Mark that heap header was modified */
-                if(H5HF_hdr_dirty(hdr) < 0)
-                    HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
-            } /* end if */
-            else {
-                H5HF_indirect_t *par_iblock;    /* Parent indirect block */
-                unsigned par_entry;             /* Entry in parent indirect block */
+            /* Mark that heap header was modified */
+            if(H5HF_hdr_dirty(hdr) < 0)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
+        } /* end if */
+        else {
+            H5HF_indirect_t *par_iblock;    /* Parent indirect block */
+            unsigned par_entry;             /* Entry in parent indirect block */
 
-                /* Get parent information */
-                par_iblock = iblock->parent;
-                par_entry = iblock->par_entry;
+            /* Get parent information */
+            par_iblock = iblock->parent;
+            par_entry = iblock->par_entry;
 
-                /* Update information about indirect block's location */
-                par_iblock->ents[par_entry].addr = addr;
+            /* Update information about indirect block's location */
+            par_iblock->ents[par_entry].addr = iblock_addr;
 
-                /* Mark that parent was modified */
-                if(H5HF_iblock_dirty(par_iblock) < 0)
-                    HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
-            } /* end if */
+            /* Mark that parent was modified */
+            if(H5HF_iblock_dirty(par_iblock) < 0)
+                HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
         } /* end if */
 
-        /* Indirect block must be in 'normal' file space now */
-        HDassert(!H5F_IS_TMP_ADDR(f, addr));
-
-	/* Write the indirect block */
-	if(H5F_block_write(f, H5FD_MEM_FHEAP_IBLOCK, addr, iblock->size, dxpl_id, buf) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFLUSH, FAIL, "unable to save fractal heap indirect block to disk")
-
-        /* Reset dirty flags */
-	iblock->cache_info.is_dirty = FALSE;
+	*new_addr = iblock_addr;
+        *flags = H5C__SERIALIZE_MOVED_FLAG;
     } /* end if */
-
-    if(destroy)
-        if(H5HF_cache_iblock_dest(f, iblock) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap indirect block")
+    else 
+	*flags = 0;
 
 done:
-    /* Release resources */
-    if(wb && H5WB_unwrap(wb) < 0)
-        HDONE_ERROR(H5E_HEAP, H5E_CLOSEERROR, FAIL, "can't close wrapped buffer")
-
     FUNC_LEAVE_NOAPI(ret_value)
-} /* H5HF_cache_iblock_flush() */
+} /* end H5HF__cache_iblock_pre_serialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_iblock_dest
+ * Function:	H5HF__cache_iblock_serialize
  *
- * Purpose:	Destroys a fractal heap indirect block in memory.
+ * Purpose:	Given a pointer to an iblock, and a pointer to a buffer of 
+ *		the appropriate size, write the contents of the iblock to the 
+ *		buffer in format appropriate for writing to disk.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Mar  6 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_iblock_dest(H5F_t *f, H5HF_indirect_t *iblock)
+static herr_t 
+H5HF__cache_iblock_serialize(const H5F_t *f, void *_image, size_t len,
+    void *_thing)
 {
-    herr_t      ret_value = SUCCEED;    /* Return value */
+    H5HF_hdr_t 		*hdr;           /* Shared fractal heap information */
+    H5HF_indirect_t     *iblock = (H5HF_indirect_t *)_thing;     /* Indirect block info */
+    uint8_t 		*image = (uint8_t *)_image;     /* Pointer into raw data buffer */
+#ifndef NDEBUG
+    unsigned 		 nchildren = 0; /* Track # of children */
+    size_t		 max_child = 0; /* Track max. child entry used */
+#endif /* NDEBUG */
+    uint32_t		 metadata_chksum; /* Computed metadata checksum value */
+    size_t 		 u;             /* Local index variable */
+    herr_t               ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC_NOERR
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(image);
     HDassert(iblock);
-    HDassert(iblock->rc == 0);
-    HDassert(iblock->hdr);
+    HDassert(iblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(iblock->cache_info.type == H5AC_FHEAP_IBLOCK);
+    HDassert(iblock->cache_info.size == iblock->size);
+    HDassert(len == iblock->size);
 
-    /* If we're going to free the space on disk, the address must be valid */
-    HDassert(!iblock->cache_info.free_file_space_on_destroy || H5F_addr_defined(iblock->cache_info.addr));
-
-    /* Check for freeing file space for indirect block */
-    if(iblock->cache_info.free_file_space_on_destroy) {
-        /* Check if the indirect block is NOT currently allocated in temp. file space */
-        /* (temp. file space does not need to be freed) */
-        if(!H5F_IS_TMP_ADDR(f, iblock->cache_info.addr)) {
-            /* Release the space on disk */
-            /* (XXX: Nasty usage of internal DXPL value! -QAK) */
-            if(H5MF_xfree(f, H5FD_MEM_FHEAP_IBLOCK, H5AC_dxpl_id, iblock->cache_info.addr, (hsize_t)iblock->size) < 0)
-                HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap indirect block")
-        } /* end if */
-    } /* end if */
+    /* Indirect block must be in 'normal' file space */
+    HDassert(!H5F_IS_TMP_ADDR(f, iblock->addr));
+    HDassert(H5F_addr_eq(iblock->addr, iblock->cache_info.addr));
 
-    /* Destroy fractal heap indirect block */
-    if(H5HF_man_iblock_dest(iblock) < 0)
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap indirect block")
+    /* Get the pointer to the shared heap header */
+    hdr = iblock->hdr;
 
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_iblock_dest() */
+    /* Set the shared heap header's file context for this operation */
+    hdr->f = f;
 
-
-/*-------------------------------------------------------------------------
- * Function:	H5HF_cache_iblock_clear
- *
- * Purpose:	Mark a fractal heap indirect block in memory as non-dirty.
- *
- * Return:	Non-negative on success/Negative on failure
- *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Mar  6 2006
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5HF_cache_iblock_clear(H5F_t *f, H5HF_indirect_t *iblock, hbool_t destroy)
-{
-    herr_t ret_value = SUCCEED;         /* Return value */
+    /* Magic number */
+    HDmemcpy(image, H5HF_IBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC);
+    image += H5_SIZEOF_MAGIC;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    /* Version # */
+    *image++ = H5HF_IBLOCK_VERSION;
 
-    /*
-     * Check arguments.
-     */
-    HDassert(iblock);
+    /* Address of heap header for heap which owns this block */
+    H5F_addr_encode(f, &image, hdr->heap_addr);
 
-    /* Reset the dirty flag.  */
-    iblock->cache_info.is_dirty = FALSE;
+    /* Offset of block in heap */
+    UINT64ENCODE_VAR(image, iblock->block_off, hdr->heap_off_size);
 
-    if(destroy)
-        if(H5HF_cache_iblock_dest(f, iblock) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap indirect block")
+    /* Encode indirect block-specific fields */
+    for(u = 0; u < (iblock->nrows * hdr->man_dtable.cparam.width); u++) {
+        /* Encode child block address */
+        H5F_addr_encode(f, &image, iblock->ents[u].addr);
+
+        /* Check for heap with I/O filters */
+        if(hdr->filter_len > 0) {
+            /* Sanity check */
+            HDassert(iblock->filt_ents);
+
+            /* Encode extra information for direct blocks */
+            if(u < (hdr->man_dtable.max_direct_rows * hdr->man_dtable.cparam.width)) {
+                /* Sanity check */
+                /* (either both the address & size are defined or both are
+                 *  not defined)
+                 */
+                HDassert((H5F_addr_defined(iblock->ents[u].addr) && iblock->filt_ents[u].size) 
+                        || (!H5F_addr_defined(iblock->ents[u].addr) && iblock->filt_ents[u].size == 0));
+
+                /* Size of filtered direct block */
+                H5F_ENCODE_LENGTH(f, image, iblock->filt_ents[u].size);
+
+                /* I/O filter mask for filtered direct block */
+                UINT32ENCODE(image, iblock->filt_ents[u].filter_mask);
+            } /* end if */
+        } /* end if */
+
+#ifndef NDEBUG
+        /* Count child blocks */
+        if(H5F_addr_defined(iblock->ents[u].addr)) {
+            nchildren++;
+            if(u > max_child)
+                max_child = u;
+        } /* end if */
+#endif /* NDEBUG */
+    } /* end for */
+
+    /* Compute checksum */
+    metadata_chksum = H5_checksum_metadata((uint8_t *)_image, (size_t)(image - (uint8_t *)_image), 0);
+
+    /* Metadata checksum */
+    UINT32ENCODE(image, metadata_chksum);
+
+    /* Sanity checks */
+    HDassert((size_t)(image - (uint8_t *)_image) == iblock->size);
+#ifndef NDEBUG
+    HDassert(nchildren == iblock->nchildren);
+    HDassert(max_child == iblock->max_child);
+#endif /* NDEBUG */
 
-done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_iblock_clear() */
+} /* end H5HF__cache_iblock_serialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_iblock_notify
+ * Function:	H5HF__cache_iblock_notify
  *
- * Purpose:	Setup / takedown flush dependencies as indirect blocks
+ * Purpose:	This function is used to create and destroy flush dependency 
+ *		relationships between iblocks and their parents as indirect blocks
  *		are loaded / inserted and evicted from the metadata cache.
  *
- * Return:	Non-negative on success/Negative on failure
+ *		In general, the parent will be another iblock, but it may be the 
+ *		header if the iblock in question is the root iblock.
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
  * Programmer:	John Mainzer
- *		5/17/14
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_iblock_notify(H5C_notify_action_t action, H5HF_indirect_t *iblock)
+static herr_t 
+H5HF__cache_iblock_notify(H5C_notify_action_t action, void *_thing)
 {
-    herr_t ret_value = SUCCEED;         /* Return value */
+    H5HF_indirect_t     *iblock = (H5HF_indirect_t *)_thing;    /* Indirect block info */
+    herr_t      	 ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
     HDassert(iblock);
     HDassert(iblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(iblock->cache_info.type == H5AC_FHEAP_IBLOCK);
     HDassert(iblock->hdr);
 
     if(action == H5AC_NOTIFY_ACTION_BEFORE_EVICT)
@@ -1309,6 +1419,7 @@ H5HF_cache_iblock_notify(H5C_notify_action_t action, H5HF_indirect_t *iblock)
 
     switch(action) {
         case H5AC_NOTIFY_ACTION_AFTER_INSERT:
+        case H5AC_NOTIFY_ACTION_AFTER_LOAD:
             if(iblock->parent) {        /* this is a child iblock */
                 /* create flush dependency with parent iblock */
                 if(H5AC_create_flush_dependency(iblock->parent, iblock) < 0)
@@ -1321,6 +1432,10 @@ H5HF_cache_iblock_notify(H5C_notify_action_t action, H5HF_indirect_t *iblock)
             } /* end else */
             break;
 
+	case H5AC_NOTIFY_ACTION_AFTER_FLUSH:
+	    /* do nothing */
+	    break;
+
         case H5AC_NOTIFY_ACTION_BEFORE_EVICT:
             if(iblock->fd_parent) {     /* this is a child iblock */
                 /* destroy flush dependency with parent iblock */
@@ -1341,38 +1456,104 @@ H5HF_cache_iblock_notify(H5C_notify_action_t action, H5HF_indirect_t *iblock)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_iblock_notify() */
+} /* end H5HF__cache_iblock_notify() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_iblock_size
+ * Function:	H5HF__cache_iblock_free_icr
  *
- * Purpose:	Compute the size in bytes of a fractal heap indirect block
- *		on disk, and return it in *size_ptr.  On failure,
- *		the value of *size_ptr is undefined.
+ * Purpose:	Unlink the supplied instance of H5HF_indirect_t from the 
+ *		fractal heap and free its memory.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Note:	The metadata cache sets the object's cache_info.magic to
+ *		H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC before calling a free_icr
+ *		callback (checked in assert).
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Mar  6 2006
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_iblock_size(const H5F_t H5_ATTR_UNUSED *f, const H5HF_indirect_t *iblock, size_t *size_ptr)
+static herr_t 
+H5HF__cache_iblock_free_icr(void *thing)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    H5HF_indirect_t	*iblock = (H5HF_indirect_t *)thing;     /* Fractal heap indirect block to free */
+    herr_t      	 ret_value = SUCCEED;    /* Return value */
 
-    /* Check arguments */
+    FUNC_ENTER_STATIC
+
+    /* Sanity checks */
     HDassert(iblock);
-    HDassert(size_ptr);
+    HDassert(iblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC);
+    HDassert(iblock->cache_info.type == H5AC_FHEAP_IBLOCK);
+    HDassert(iblock->rc == 0);
+    HDassert(iblock->hdr);
+
+    /* Destroy fractal heap indirect block */
+    if(H5HF_man_iblock_dest(iblock) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap indirect block")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5HF__cache_iblock_free_icr() */
+
+/*********************************************************/
+/* metadata cache callback definitions for direct blocks */
+/*********************************************************/
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF__cache_dblock_get_load_size()
+ *
+ * Purpose:	Determine the size of the direct block on disk image, and 
+ *		return it in *image_len.
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5HF__cache_dblock_get_load_size(const void *_udata, size_t *image_len)
+{
+    const H5HF_dblock_cache_ud_t *udata = (const H5HF_dblock_cache_ud_t *)_udata;    /* User data for callback */
+    const H5HF_parent_t         *par_info; /* Pointer to parent information */
+    const H5HF_hdr_t            *hdr;     /* Shared fractal heap information */
+    size_t                      size;
+
+    FUNC_ENTER_STATIC_NOERR
+
+    /* Sanity checks */
+    HDassert(udata);
+    HDassert(image_len);
+    par_info = (const H5HF_parent_t *)(&(udata->par_info));
+    HDassert(par_info);
+    hdr = par_info->hdr;
+    HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
+
+    /* Check for I/O filters on this heap */
+    if(hdr->filter_len > 0) {
+        /* Check for root direct block */
+        if(par_info->iblock == NULL)
+            size = hdr->pline_root_direct_size;
+        else
+            size = par_info->iblock->filt_ents[par_info->entry].size;
+    } /* end if */
+    else
+        size = udata->dblock_size;
 
-    /* Set size value */
-    *size_ptr = iblock->size;
+    *image_len = size;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_cache_iblock_size() */
+} /* end H5HF__cache_dblock_get_load_size() */
 
 /*********************************************************/
 /* metadata cache callback definitions for direct blocks */
@@ -1380,49 +1561,55 @@ H5HF_cache_iblock_size(const H5F_t H5_ATTR_UNUSED *f, const H5HF_indirect_t *ibl
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_dblock_load
+ * Function:	H5HF__cache_dblock_deserialize
  *
- * Purpose:	Loads a fractal heap direct block from the disk.
+ * Purpose:	Given a buffer containing the on disk image of a direct
+ *		block, allocate an instance of H5HF_direct_t, load the data
+ *		in the buffer into this new instance, and return a pointer to
+ *		it.
  *
- * Return:	Success:	Pointer to a new fractal heap direct block
+ *		As best I can tell, the size of the direct block image is fully
+ *		know before the image is loaded, so this function should succeed
+ *		unless the image is corrupt or memory allocation fails.
  *
+ * Return:	Success:	Pointer to in core representation
  *		Failure:	NULL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 27 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static H5HF_direct_t *
-H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
+static void *
+H5HF__cache_dblock_deserialize(const void *_image, size_t len, void *_udata,
+    hbool_t H5_ATTR_UNUSED *dirty)
 {
     H5HF_hdr_t          *hdr;           /* Shared fractal heap information */
     H5HF_dblock_cache_ud_t *udata = (H5HF_dblock_cache_ud_t *)_udata;   /* User data for callback */
     H5HF_parent_t       *par_info;      /* Pointer to parent information */
-    H5HF_direct_t	*dblock = NULL; /* Direct block info */
-    const uint8_t	*p;             /* Pointer into raw data buffer */
+    H5HF_direct_t       *dblock = NULL; /* Direct block info */
+    const uint8_t       *image;         /* Pointer into raw data buffer */
     haddr_t             heap_addr;      /* Address of heap header in the file */
-    H5HF_direct_t	*ret_value;     /* Return value */
+    void *              ret_value;      /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /* Check arguments */
-    HDassert(f);
-    HDassert(H5F_addr_defined(addr));
-    HDassert(udata != NULL);
-    HDassert(udata->f != NULL);
-    HDassert(udata->dblock_size > 0);
+    /* Sanity checks */
+    HDassert(_image);
+    HDassert(udata);
+    par_info = (H5HF_parent_t *)(&(udata->par_info));
+    HDassert(par_info);
+    hdr = par_info->hdr;
+    HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
+    HDassert(dirty);
 
     /* Allocate space for the fractal heap direct block */
     if(NULL == (dblock = H5FL_MALLOC(H5HF_direct_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
     HDmemset(&dblock->cache_info, 0, sizeof(H5AC_info_t));
 
-    /* Get the pointer to the shared heap header */
-    par_info = (H5HF_parent_t *)(&(udata->par_info));
-    hdr = par_info->hdr;
-
     /* Set the shared heap header's file context for this operation */
     hdr->f = udata->f;
 
@@ -1435,6 +1622,10 @@ H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
     dblock->size = udata->dblock_size;
     dblock->file_size = 0;
 
+    /* initialize fields used in serialization */
+    dblock->write_buf = NULL;
+    dblock->write_size = 0;
+
     /* Allocate block buffer */
 /* XXX: Change to using free-list factories */
     if(NULL == (dblock->blk = H5FL_BLK_MALLOC(direct_block, (size_t)dblock->size)))
@@ -1449,28 +1640,21 @@ H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         unsigned filter_mask;   /* Excluded filters for direct block */
 
         /* Check for root direct block */
-        if(par_info->iblock == NULL) {
-            /* Sanity check */
-            HDassert(H5F_addr_eq(hdr->man_dtable.table_addr, addr));
-
+        if(par_info->iblock == NULL)
             /* Set up parameters to read filtered direct block */
             read_size = hdr->pline_root_direct_size;
-        } /* end if */
-        else {
-            /* Sanity check */
-            HDassert(H5F_addr_eq(par_info->iblock->ents[par_info->entry].addr, addr));
-
+        else
             /* Set up parameters to read filtered direct block */
             read_size = par_info->iblock->filt_ents[par_info->entry].size;
-        } /* end else */
+        HDassert(len == read_size);
 
-        /* Allocate buffer to perform I/O filtering on */
+        /* Allocate buffer to perform I/O filtering on and copy image into
+         * it.  Must do this as H5Z_pipeline() may re-sized the buffer 
+         * provided to it.
+         */
         if(NULL == (read_buf = H5MM_malloc(read_size)))
             HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, NULL, "memory allocation failed for pipeline buffer")
-
-        /* Read filtered direct block from disk */
-        if(H5F_block_read(f, H5FD_MEM_FHEAP_DBLOCK, addr, read_size, dxpl_id, read_buf) < 0)
-            HGOTO_ERROR(H5E_HEAP, H5E_READERROR, NULL, "can't read fractal heap direct block")
+        HDmemcpy(read_buf, _image, len);
 
         /* Push direct block data through I/O filter pipeline */
         nbytes = read_size;
@@ -1488,25 +1672,25 @@ H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         H5MM_xfree(read_buf);
     } /* end if */
     else {
-        /* Read direct block from disk */
-        if(H5F_block_read(f, H5FD_MEM_FHEAP_DBLOCK, addr, dblock->size, dxpl_id, dblock->blk) < 0)
-            HGOTO_ERROR(H5E_HEAP, H5E_READERROR, NULL, "can't read fractal heap direct block")
+        /* copy image to dblock->blk */
+        HDassert(dblock->size == len);
+        HDmemcpy(dblock->blk, _image, dblock->size);
     } /* end else */
 
     /* Start decoding direct block */
-    p = dblock->blk;
+    image = dblock->blk;
 
     /* Magic number */
-    if(HDmemcmp(p, H5HF_DBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC))
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "wrong fractal heap direct block signature")
-    p += H5_SIZEOF_MAGIC;
+    if(HDmemcmp(image, H5HF_DBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC))
+        HGOTO_ERROR(H5E_HEAP, H5E_BADVALUE, NULL, "wrong fractal heap direct block signature")
+    image += H5_SIZEOF_MAGIC;
 
     /* Version */
-    if(*p++ != H5HF_DBLOCK_VERSION)
+    if(*image++ != H5HF_DBLOCK_VERSION)
         HGOTO_ERROR(H5E_HEAP, H5E_VERSION, NULL, "wrong fractal heap direct block version")
 
     /* Address of heap that owns this block (just for file integrity checks) */
-    H5F_addr_decode(udata->f, &p, &heap_addr);
+    H5F_addr_decode(udata->f, &image, &heap_addr);
     if(H5F_addr_ne(heap_addr, hdr->heap_addr))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "incorrect heap header address for direct block")
 
@@ -1521,7 +1705,7 @@ H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
     } /* end if */
 
     /* Offset of heap within the heap's address space */
-    UINT64DECODE_VAR(p, dblock->block_off, hdr->heap_off_size);
+    UINT64DECODE_VAR(image, dblock->block_off, hdr->heap_off_size);
 
     /* Decode checksum on direct block, if requested */
     if(hdr->checksum_dblocks) {
@@ -1529,11 +1713,11 @@ H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
         uint32_t computed_chksum;       /* Computed metadata checksum value */
 
         /* Metadata checksum */
-        UINT32DECODE(p, stored_chksum);
+        UINT32DECODE(image, stored_chksum);
 
         /* Reset checksum field, for computing the checksum */
         /* (Casting away const OK - QAK) */
-        HDmemset((uint8_t *)p - H5HF_SIZEOF_CHKSUM, 0, (size_t)H5HF_SIZEOF_CHKSUM);
+        HDmemset((uint8_t *)image - H5HF_SIZEOF_CHKSUM, 0, (size_t)H5HF_SIZEOF_CHKSUM);
 
         /* Compute checksum on entire direct block */
         computed_chksum = H5_checksum_metadata(dblock->blk, dblock->size, 0);
@@ -1544,10 +1728,10 @@ H5HF_cache_dblock_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *_udata)
     } /* end if */
 
     /* Sanity check */
-    HDassert((size_t)(p - dblock->blk) == (size_t)H5HF_MAN_ABS_DIRECT_OVERHEAD(hdr));
+    HDassert((size_t)(image - dblock->blk) == (size_t)H5HF_MAN_ABS_DIRECT_OVERHEAD(hdr));
 
     /* Set return value */
-    ret_value = dblock;
+    ret_value = (void *)dblock;
 
 done:
     if(!ret_value && dblock)
@@ -1555,402 +1739,646 @@ done:
             HDONE_ERROR(H5E_HEAP, H5E_CANTFREE, NULL, "unable to destroy fractal heap direct block")
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_dblock_load() */
+} /* end H5HF__cache_dblock_deserialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_dblock_flush
+ * Function:	H5HF__cache_dblock_image_len
  *
- * Purpose:	Flushes a dirty fractal heap direct block to disk.
+ * Purpose:	Report the actual size of the direct block image on disk.
+ *		Note that this value will probably be incorrect if compression 
+ *		is enabled and the entry is dirty.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 27 2006
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_dblock_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HF_direct_t *dblock, unsigned H5_ATTR_UNUSED * flags_ptr)
+static herr_t 
+H5HF__cache_dblock_image_len(const void *_thing, size_t *image_len, hbool_t *compressed_ptr, size_t *compressed_image_len_ptr)
 {
-    herr_t      ret_value = SUCCEED;    /* Return value */
+    const H5HF_direct_t    *dblock = (const H5HF_direct_t *)_thing;     /* Direct block info */
+    const H5HF_indirect_t  *par_iblock; /* Parent iblock */
+    const H5HF_hdr_t  *hdr;             /* Shared fractal heap information */
+    hbool_t	      compressed;
+    size_t            size;
+    size_t	      compressed_size;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC_NOERR
 
-    /* check arguments */
-    HDassert(f);
-    HDassert(H5F_addr_defined(addr));
+    /* Sanity checks */
     HDassert(dblock);
+    HDassert(dblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(dblock->cache_info.type == H5AC_FHEAP_DBLOCK);
+    HDassert(image_len);
+    HDassert(compressed_ptr);
+    HDassert(compressed_image_len_ptr);
 
-    if(dblock->cache_info.is_dirty) {
-        H5HF_hdr_t *hdr;        /* Shared fractal heap information */
-        hbool_t at_tmp_addr = H5F_IS_TMP_ADDR(f, addr);     /* Flag to indicate direct block is at temporary address */
-        void *write_buf;        /* Pointer to buffer to write out */
-        size_t write_size;      /* Size of buffer to write out */
-        uint8_t *p;             /* Pointer into raw data buffer */
+    /* Set up convenience variables */
+    hdr = dblock->hdr;
+    par_iblock = dblock->parent;
 
-        /* Get the pointer to the shared heap header */
-        hdr = dblock->hdr;
+    /* Check for I/O filters on this heap */
+    if(hdr->filter_len > 0) {
 
-        /* Set the shared heap header's file context for this operation */
-        hdr->f = f;
+        /* Filters are enabled, so set compressed to TRUE, and set 
+ 	 * size equal to the uncompressed size of the direct block.
+         * If the data is available, set compressed_size to the compressed
+         * size of the direct block -- otherwise set it equal to the 
+         * uncompressed size.  
+         *
+         * We have three possible scenarios here.
+         *
+         * First, the block may never have been flushed.  In this
+         * case, both dblock->file_size and the size stored in the 
+         * parent (either the header or the parent iblock) will all 
+         * be zero.  In this case, return the uncompressed size 
+         * stored in dblock->size as the compressed size.
+         *
+         * Second, the block may have just been serialized, in which
+         * case, dblock->file_size should be zero, and the correct 
+         * on disk size should be stored in the parent (again, either
+         * the header or the parent iblock as case may be).
+         * 
+         * Third, we may be in the process of discarding this 
+         * dblock without writing it.  In this case, dblock->file_size
+         * should be non-zero and have the correct size.  Note that 
+         * in this case, the direct block will have been detached,
+         * and thus looking up the parent will likely return incorrect
+         * data.
+         */
+        size            = dblock->size;
+        compressed      = TRUE;
+        compressed_size = dblock->size; /* will overwrite if compressed 
+                                         * size is available.
+                                         */
+
+        if(dblock->file_size != 0) 
+            compressed_size = dblock->file_size;
+        else {
+            if(par_iblock) {
+                unsigned          par_entry;  /* Entry in parent indirect block */
 
-        HDassert(dblock->blk);
-        p = dblock->blk;
+                par_entry = dblock->par_entry;
+                compressed_size = par_iblock->filt_ents[par_entry].size;
 
-        /* Magic number */
-        HDmemcpy(p, H5HF_DBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC);
-        p += H5_SIZEOF_MAGIC;
+            } /* end if */
+            else {
+                compressed_size = hdr->pline_root_direct_size;
+            }
 
-        /* Version # */
-        *p++ = H5HF_DBLOCK_VERSION;
+            if(compressed_size == 0)
+                compressed_size = dblock->size;
 
-        /* Address of heap header for heap which owns this block */
-        H5F_addr_encode(f, &p, hdr->heap_addr);
+        } /* end else */
+    } /* end if */
+    else {
+        size = dblock->size;
+        compressed = FALSE;
+        compressed_size = 0; /* a convenient, invalid value */
+    }
 
-        /* Offset of block in heap */
-        UINT64ENCODE_VAR(p, dblock->block_off, hdr->heap_off_size);
+    HDassert(size > 0);
 
-        /* Metadata checksum */
-        if(hdr->checksum_dblocks) {
-            uint32_t metadata_chksum;       /* Computed metadata checksum value */
+    *image_len                = size;
+    *compressed_ptr           = compressed;
+    *compressed_image_len_ptr = compressed_size;
 
-            /* Clear the checksum field, to compute the checksum */
-            HDmemset(p, 0, (size_t)H5HF_SIZEOF_CHKSUM);
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5HF__cache_dblock_image_len() */
 
-            /* Compute checksum on entire direct block */
-            metadata_chksum = H5_checksum_metadata(dblock->blk, dblock->size, 0);
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF__cache_dblock_pre_serialize
+ *
+ * Purpose:	In principle, the purpose of this function is to determine
+ *		the size and location of the disk image of the target direct 
+ *		block.  In this case, the uncompressed size of the block is
+ *		fixed, but sined the H5C__CLASS_COMPRESSED_FLAG is set, 
+ *		we may need to compute and report the compressed size.
+ *
+ *		This is a bit sticky in the case of a direct block when I/O 
+ *		filters are enabled, as the size of the compressed version
+ *		of the on disk image is not known until the direct block has 
+ *		been run through the filters.  Further, the location of the 
+ *		on disk image may change if the compressed size of the image 
+ *		changes as well.
+ *
+ *		To complicate matters further, the direct block may have been 
+ *		initially allocated in temporary (AKA imaginary) file space. 
+ *		In this case, we must relocate the direct block's on disk 
+ *		image to real file space regardless of whether it has changed 
+ *		size.
+ *
+ *		One simplifying factor is the direct block's "blk" field, 
+ *		which contains a pointer to a buffer which (with the exception
+ *		of a small header) contains the on disk image in uncompressed 
+ *		form.
+ *
+ *		To square this particular circle, this function does 
+ *		everything the serialize function usually does, with the 
+ *		exception of copying the image into the image buffer provided 
+ *		to the serialize function by the metadata cache.  The data to 
+ *		copy is provided to the serialize function in a buffer pointed
+ *		to by the write_buf field.
+ *
+ *		If I/O filters are enabled, on exit, 
+ *		H5HF__cache_dblock_pre_serialize() sets the write_buf field to 
+ *		point to a buffer containing the filtered image of the direct
+ *		block.  The serialize function should free this block, and set
+ *		the write_buf field to NULL after copying it into the image 
+ *		buffer provided by the metadata cache.
+ *
+ *		If I/O filters are not enabled, this function prepares 
+ *		the buffer pointed to by the blk field for copying to the 
+ *		image buffer provided by the metadata cache, and sets the 
+ *		write_buf field equal to the blk field.  In this case, the 
+ *		serialize function should simply set the write_buf field to 
+ *		NULL after copying the direct block image into the image 
+ *		buffer.
+ *
+ *		In both of the above cases, the length of the buffer pointed 
+ *		to by write_buf is provided in the write_len field.  This 
+ *		field must contain 0 on entry to this function, and should 
+ *		be set back to 0 at the end of the serialize function.
+ *
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t 
+H5HF__cache_dblock_pre_serialize(const H5F_t *f, hid_t dxpl_id, void *_thing,
+    haddr_t addr, size_t len, size_t compressed_len, haddr_t *new_addr, 
+    size_t H5_ATTR_UNUSED *new_len, size_t *new_compressed_len, unsigned *flags)
+{
+    hbool_t 		 at_tmp_addr;  /* Flag to indicate direct block is */
+                                       /* at temporary address */
+    haddr_t		 dblock_addr;
+    H5HF_hdr_t          *hdr;           /* Shared fractal heap information */
+    H5HF_direct_t       *dblock = (H5HF_direct_t *)_thing;      /* Direct block info */
+    H5HF_indirect_t 	*par_iblock;    /* Parent indirect block */
+    unsigned		 par_entry;     /* Entry in parent indirect block */
+    void 		*write_buf;     /* Pointer to buffer to write out */
+    size_t 		 write_size;    /* Size of buffer to write out */
+    uint8_t 		*image;         /* Pointer into raw data buffer */
+    unsigned		 dblock_flags = 0;
+    herr_t               ret_value = SUCCEED;    /* Return value */
 
-            /* Metadata checksum */
-            UINT32ENCODE(p, metadata_chksum);
-        } /* end if */
+    FUNC_ENTER_STATIC
 
-        /* Sanity check */
-        HDassert((size_t)(p - dblock->blk) == (size_t)H5HF_MAN_ABS_DIRECT_OVERHEAD(hdr));
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(dblock);
+    HDassert(dblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(dblock->cache_info.type == H5AC_FHEAP_DBLOCK);
+    HDassert(dblock->write_buf == NULL);
+    HDassert(dblock->write_size == 0);
+    HDassert(dblock->cache_info.size == len);
+    HDassert(H5F_addr_defined(addr));
+    HDassert(len == dblock->size);
+    HDassert(new_addr);
+    HDassert(new_compressed_len);
+    HDassert(flags);
 
-        /* Check for I/O filters on this heap */
-        if(hdr->filter_len > 0) {
-            H5Z_cb_t filter_cb = {NULL, NULL};  /* Filter callback structure */
-            size_t nbytes;                      /* Number of bytes used */
-            unsigned filter_mask = 0;           /* Filter mask for block */
+    /* Set up local variables */
+    hdr = dblock->hdr;
+    dblock_addr = addr;    /* will update dblock_addr if we move the block */
 
-            /* Allocate buffer to perform I/O filtering on */
-            write_size = dblock->size;
-            if(NULL == (write_buf = H5MM_malloc(write_size)))
-                HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "memory allocation failed for pipeline buffer")
-            HDmemcpy(write_buf, dblock->blk, write_size);
+    /* dblock->size must match dblock->cache_info.size */
+    HDassert(dblock->cache_info.size == dblock->size);
 
-            /* Push direct block data through I/O filter pipeline */
-            nbytes = write_size;
-            if(H5Z_pipeline(&(hdr->pline), 0, &filter_mask, H5Z_ENABLE_EDC, filter_cb, &nbytes, &write_size, &write_buf) < 0)
-                HGOTO_ERROR(H5E_HEAP, H5E_WRITEERROR, FAIL, "output pipeline failed")
+    /* Set the shared heap header's file context for this operation */
+    hdr->f = (H5F_t *)f;
 
-            /* Use the compressed number of bytes as the size to write */
-            write_size = nbytes;
+    HDassert(hdr);
+    HDassert(hdr->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(hdr->cache_info.type == H5AC_FHEAP_HDR);
 
-            /* Check for root direct block */
-            if(dblock->parent == NULL) {
-                hbool_t hdr_changed = FALSE;    /* Whether the header information changed */
+    if(dblock->parent) {
+	/* this is the common case, in which the direct block is the child 
+         * of an indirect block.  Set up the convenience variables we will
+         * need if the address and/or compressed size of the on disk image 
+         * of the direct block changes, and do some sanity checking in 
+         * passing.
+         */
+        par_iblock = dblock->parent;
+	par_entry = dblock->par_entry;
 
-                /* Sanity check */
-                HDassert(H5F_addr_eq(hdr->man_dtable.table_addr, addr));
-                HDassert(hdr->pline_root_direct_size > 0);
+	HDassert(par_iblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+	HDassert(par_iblock->cache_info.type == H5AC_FHEAP_IBLOCK);
+        HDassert(H5F_addr_eq(par_iblock->ents[par_entry].addr, addr));
+    } /* end if */
+    else {
+	/* the direct block is a root direct block -- just set par_iblock
+         * to NULL, as the field will not be used.
+         */
+	par_iblock = NULL;
+    } /* end else */
 
-                /* Check if the filter mask changed */
-                if(hdr->pline_root_direct_filter_mask != filter_mask) {
-                    hdr->pline_root_direct_filter_mask = filter_mask;
-                    hdr_changed = TRUE;
-                } /* end if */
+    at_tmp_addr = H5F_IS_TMP_ADDR(f, addr);
 
-                /* Check if we need to re-size the block on disk */
-                if(hdr->pline_root_direct_size != write_size || at_tmp_addr) {
-                    /* Check if the direct block is NOT currently allocated in temp. file space */
-                    /* (temp. file space does not need to be freed) */
-                    if(!at_tmp_addr) {
-                        /* Release direct block's current disk space */
-                        if(H5MF_xfree(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, addr, (hsize_t)hdr->pline_root_direct_size) < 0)
-                            HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap direct block")
-                    } /* end if */
+    /* Begin by preping the direct block to be written to disk.  Do
+     * this by writing the correct magic number, the dblock version, 
+     * the address of the header, the offset of the block in the heap, 
+     * and the checksum at the beginning of the block.
+     */
 
-                    /* Allocate space for the compressed direct block */
-                    if(HADDR_UNDEF == (addr = H5MF_alloc(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
-                        HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
+    HDassert(dblock->blk);
+    image = dblock->blk;
 
-                    /* Let the metadata cache know, if the block moved */
-                    if(!H5F_addr_eq(hdr->man_dtable.table_addr, addr))
-                        if(H5AC_move_entry(f, H5AC_FHEAP_DBLOCK, hdr->man_dtable.table_addr, addr) < 0)
-                            HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
+    /* Magic number */
+    HDmemcpy(image, H5HF_DBLOCK_MAGIC, (size_t)H5_SIZEOF_MAGIC);
+    image += H5_SIZEOF_MAGIC;
 
-                    /* Update information about compressed direct block's location & size */
-                    hdr->man_dtable.table_addr = addr;
-                    hdr->pline_root_direct_size = write_size;
+    /* Version # */
+    *image++ = H5HF_DBLOCK_VERSION;
 
-                    /* Note that heap header was modified */
-                    hdr_changed = TRUE;
-                } /* end if */
+    /* Address of heap header for heap which owns this block */
+    H5F_addr_encode(f, &image, hdr->heap_addr);
 
-                /* Check if heap header was modified */
-                if(hdr_changed)
-                    if(H5HF_hdr_dirty(hdr) < 0)
-                        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
-            } /* end if */
-            else {
-                hbool_t par_changed = FALSE;    /* Whether the parent's information changed */
-                H5HF_indirect_t *par_iblock;    /* Parent indirect block */
-                unsigned par_entry;             /* Entry in parent indirect block */
+    /* Offset of block in heap */
+    UINT64ENCODE_VAR(image, dblock->block_off, hdr->heap_off_size);
 
-                /* Get parent information */
-                par_iblock = dblock->parent;
-                par_entry = dblock->par_entry;
+    /* Metadata checksum */
+    if(hdr->checksum_dblocks) {
+        uint32_t metadata_chksum;       /* Computed metadata checksum value */
 
-                /* Sanity check */
-                HDassert(H5F_addr_eq(par_iblock->ents[par_entry].addr, addr));
-                HDassert(par_iblock->filt_ents[par_entry].size > 0);
+        /* Clear the checksum field, to compute the checksum */
+        HDmemset(image, 0, (size_t)H5HF_SIZEOF_CHKSUM);
 
-                /* Check if the filter mask changed */
-                if(par_iblock->filt_ents[par_entry].filter_mask != filter_mask) {
-                    par_iblock->filt_ents[par_entry].filter_mask = filter_mask;
-                    par_changed = TRUE;
-                } /* end if */
+        /* Compute checksum on entire direct block */
+        metadata_chksum = H5_checksum_metadata(dblock->blk, dblock->size, 0);
 
-                /* Check if we need to re-size the block on disk */
-                if(par_iblock->filt_ents[par_entry].size != write_size || at_tmp_addr) {
-                    /* Check if the direct block is NOT currently allocated in temp. file space */
-                    /* (temp. file space does not need to be freed) */
-                    if(!at_tmp_addr) {
-                        /* Release direct block's current disk space */
-                        if(H5MF_xfree(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, addr, (hsize_t)par_iblock->filt_ents[par_entry].size) < 0)
-                            HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap direct block")
-                    } /* end if */
+        /* Metadata checksum */
+        UINT32ENCODE(image, metadata_chksum);
+    } /* end if */
 
-                    /* Allocate space for the compressed direct block */
-                    if(HADDR_UNDEF == (addr = H5MF_alloc(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
-                        HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
+    /* at this point, dblock->blk should point to an uncompressed image of 
+     * the direct block.  If I/O filters are not enabled, this image should
+     * be ready to hand off to the metadata cache.
+     */
 
-                    /* Let the metadata cache know, if the block moved */
-                    if(!H5F_addr_eq(par_iblock->ents[par_entry].addr, addr))
-                        if(H5AC_move_entry(f, H5AC_FHEAP_DBLOCK, par_iblock->ents[par_entry].addr, addr) < 0)
-                            HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
+    /* Sanity check */
+    HDassert((size_t)(image - dblock->blk) == (size_t)H5HF_MAN_ABS_DIRECT_OVERHEAD(hdr));
 
-                    /* Update information about compressed direct block's location & size */
-                    par_iblock->ents[par_entry].addr = addr;
-                    par_iblock->filt_ents[par_entry].size = write_size;
+    /* If I/O filters are enabled on this heap, we must run the direct block
+     * image through the filters to obtain the image that we will hand off
+     * to the metadata cache.
+     */
 
-                    /* Note that parent was modified */
-                    par_changed = TRUE;
-                } /* end if */
+    /* Check for I/O filters on this heap */
+    if(hdr->filter_len > 0) {
+        H5Z_cb_t filter_cb = {NULL, NULL};  /* Filter callback structure */
+        size_t nbytes;                      /* Number of bytes used */
+        unsigned filter_mask = 0;           /* Filter mask for block */
 
-                /* Check if parent was modified */
-                if(par_changed)
-                    if(H5HF_iblock_dirty(par_iblock) < 0)
-                        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
-            } /* end else */
-        } /* end if */
-        else {
-            write_buf = dblock->blk;
-            write_size = dblock->size;
+        /* Allocate buffer to perform I/O filtering on */
+        write_size = dblock->size;
 
-            /* Check for needing to re-allocate direct block from 'temp.' to 'normal' file space */
-            if(at_tmp_addr) {
-                /* Check for root direct block */
-                if(NULL == dblock->parent) {
-                    /* Sanity check */
-                    HDassert(H5F_addr_eq(hdr->man_dtable.table_addr, addr));
+        if(NULL == (write_buf = H5MM_malloc(write_size)))
+            HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "memory allocation failed for pipeline buffer")
+        HDmemcpy(write_buf, dblock->blk, write_size);
 
-                    /* Allocate 'normal' space for the direct block */
-                    if(HADDR_UNDEF == (addr = H5MF_alloc(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
-                        HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
+        /* Push direct block data through I/O filter pipeline */
+        nbytes = write_size;
+        if(H5Z_pipeline(&(hdr->pline), 0, &filter_mask, H5Z_ENABLE_EDC, filter_cb, &nbytes, &write_size, &write_buf) < 0)
+            HGOTO_ERROR(H5E_HEAP, H5E_WRITEERROR, FAIL, "output pipeline failed")
+
+        /* Use the compressed number of bytes as the size to write */
+        write_size = nbytes;
+
+        /* If the size and/or location of the on disk image of the 
+         * direct block changes, we must touch up its parent to reflect
+         * these changes.  Do this differently depending on whether the
+         * direct block's parent is an indirect block or (rarely) the 
+         * fractal heap header.  In this case, the direct block is known
+         * as a root direct block.
+         */
 
-                    /* Sanity check */
-                    HDassert(!H5F_addr_eq(hdr->man_dtable.table_addr, addr));
+        /* Check for root direct block */
+        if(dblock->parent == NULL) {
+            hbool_t hdr_changed = FALSE; /* Whether the header info changed */
 
-                    /* Let the metadata cache know the block moved */
-                    if(H5AC_move_entry(f, H5AC_FHEAP_DBLOCK, hdr->man_dtable.table_addr, addr) < 0)
-                        HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
+            /* Sanity check */
+            HDassert(H5F_addr_eq(hdr->man_dtable.table_addr, addr));
+            HDassert(hdr->pline_root_direct_size > 0);
 
-                    /* Update information about direct block's location */
-                    hdr->man_dtable.table_addr = addr;
+            /* Check if the filter mask changed */
+            if(hdr->pline_root_direct_filter_mask != filter_mask) {
+                hdr->pline_root_direct_filter_mask = filter_mask;
+                hdr_changed = TRUE;
+            } /* end if */
+
+            /* verify that the cache's last record of the compressed 
+             * size matches the heap's last record.  This value will
+             * likely change shortly.
+             */
+            HDassert(compressed_len == hdr->pline_root_direct_size);
 
-                    /* Mark that heap header was modified */
-                    if(H5HF_hdr_dirty(hdr) < 0)
-                        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
+            /* Check if we need to re-size the block on disk */
+            if(hdr->pline_root_direct_size != write_size || at_tmp_addr) {
+                /* Check if the direct block is NOT currently allocated 
+                 * in temp. file space 
+                 *
+                 * (temp. file space does not need to be freed) 
+                 */
+                if(!at_tmp_addr) {
+                    /* Release direct block's current disk space */
+                    if(H5MF_xfree(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, addr, (hsize_t)hdr->pline_root_direct_size) < 0)
+                        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap direct block")
                 } /* end if */
-                else {
-                    H5HF_indirect_t *par_iblock;    /* Parent indirect block */
-                    unsigned par_entry;             /* Entry in parent indirect block */
 
-                    /* Get parent information */
-                    par_iblock = dblock->parent;
-                    par_entry = dblock->par_entry;
+                /* Allocate space for the compressed direct block */
+                if(HADDR_UNDEF == (dblock_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
+                    HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
 
-                    /* Sanity check */
-                    HDassert(H5F_addr_eq(par_iblock->ents[par_entry].addr, addr));
+                /* Let the metadata cache know, if the block moved */
+                if(!H5F_addr_eq(hdr->man_dtable.table_addr, dblock_addr))
+                    if(H5AC_move_entry((H5F_t *)f, H5AC_FHEAP_DBLOCK, hdr->man_dtable.table_addr, dblock_addr) < 0)
+                        HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
 
-                    /* Allocate 'normal' space for the direct block */
-                    if(HADDR_UNDEF == (addr = H5MF_alloc(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
-                        HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
+                /* Update information about compressed direct block's 
+                 * location & size 
+                 */
+                HDassert(hdr->man_dtable.table_addr == addr);
+                HDassert(hdr->pline_root_direct_size == compressed_len);
+                hdr->man_dtable.table_addr = dblock_addr;
+                hdr->pline_root_direct_size = write_size;
 
-                    /* Sanity check */
-                    HDassert(!H5F_addr_eq(par_iblock->ents[par_entry].addr, addr));
+                /* Note that heap header was modified */
+                hdr_changed = TRUE;
+            } /* end if */
+
+            /* Check if heap header was modified */
+            if(hdr_changed)
+                if(H5HF_hdr_dirty(hdr) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
+        } /* end if */
+        else { /* the direct block's parent is an indirect block */
+            hbool_t par_changed = FALSE;  /* Whether the parent's infochanged */
 
-                    /* Let the metadata cache know the block moved */
-                    if(H5AC_move_entry(f, H5AC_FHEAP_DBLOCK, par_iblock->ents[par_entry].addr, addr) < 0)
+            /* Sanity check */
+            HDassert(par_iblock);
+            HDassert(par_iblock->filt_ents[par_entry].size > 0);
+
+            /* Check if the filter mask changed */
+            if(par_iblock->filt_ents[par_entry].filter_mask != filter_mask) {
+                par_iblock->filt_ents[par_entry].filter_mask = filter_mask;
+                par_changed = TRUE;
+            } /* end if */
+
+            /* verify that the cache's last record of the compressed 
+             * size matches the heap's last record.  This value will
+             * likely change shortly.
+             */
+            HDassert(compressed_len == par_iblock->filt_ents[par_entry].size);
+
+            /* Check if we need to re-size the block on disk */
+            if(par_iblock->filt_ents[par_entry].size != write_size || at_tmp_addr) {
+                /* Check if the direct block is NOT currently allocated 
+                 * in temp. file space 
+                 *
+                 * (temp. file space does not need to be freed) 
+                 */
+                if(!at_tmp_addr) {
+                    /* Release direct block's current disk space */
+                    if(H5MF_xfree(f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, addr, (hsize_t)par_iblock->filt_ents[par_entry].size) < 0)
+                        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap direct block")
+                } /* end if */
+
+                /* Allocate space for the compressed direct block */
+                if(HADDR_UNDEF == (dblock_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
+                    HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
+
+                /* Let the metadata cache know, if the block moved */
+                if(!H5F_addr_eq(par_iblock->ents[par_entry].addr, dblock_addr))
+                    if(H5AC_move_entry((H5F_t *)f, H5AC_FHEAP_DBLOCK, par_iblock->ents[par_entry].addr, dblock_addr) < 0)
                         HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
 
-                    /* Update information about direct block's location */
-                    par_iblock->ents[par_entry].addr = addr;
+                /* Update information about compressed direct block's 
+                 * location & size 
+                 */
+                HDassert(par_iblock->ents[par_entry].addr == addr);
+                HDassert(par_iblock->filt_ents[par_entry].size == compressed_len);
+                par_iblock->ents[par_entry].addr = dblock_addr;
+                par_iblock->filt_ents[par_entry].size = write_size;
 
-                    /* Mark that parent was modified */
-                    if(H5HF_iblock_dirty(par_iblock) < 0)
-                        HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
-                } /* end else */
+                /* Note that parent was modified */
+                par_changed = TRUE;
             } /* end if */
+
+            /* Check if parent was modified */
+            if(par_changed)
+                if(H5HF_iblock_dirty(par_iblock) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
         } /* end else */
+    } /* end if */
+    else {
+        /* I/O filters are not enabled -- thus all we need to do is check to 
+         * see if the direct block is in temporary (AKA imaginary) file 
+         * space, and move it to real file space if it is.
+         *
+         * As in the I/O filters case above, we will have to touch up the 
+         * direct blocks parent if the direct block is relocated.
+         *
+         * Recall that temporary file space need not be freed, which 
+         * simplifies matters slightly.
+         */
+        write_buf = dblock->blk;
+        write_size = dblock->size;
 
-        /* Direct block must be in 'normal' file space now */
-        HDassert(!H5F_IS_TMP_ADDR(f, addr));
+        /* Check to see if we must re-allocate direct block from 'temp.' 
+         * to 'normal' file space 
+         */
+        if(at_tmp_addr) {
+            /* Check for root direct block */
+            if(NULL == dblock->parent) {
+                /* Sanity check */
+                HDassert(H5F_addr_eq(hdr->man_dtable.table_addr, addr));
 
-	/* Write the direct block */
-	if(H5F_block_write(f, H5FD_MEM_FHEAP_DBLOCK, addr, write_size, dxpl_id, write_buf) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFLUSH, FAIL, "unable to save fractal heap direct block to disk")
+                /* Allocate 'normal' space for the direct block */
+                if(HADDR_UNDEF == (dblock_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
+                    HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
 
-        /* Release the write buffer, if it was allocated */
-        if(write_buf != dblock->blk)
-            H5MM_xfree(write_buf);
+                /* Sanity check */
+                HDassert(!H5F_addr_eq(hdr->man_dtable.table_addr, dblock_addr));
 
-	dblock->cache_info.is_dirty = FALSE;
-    } /* end if */
+                /* Let the metadata cache know the block moved */
+                if(H5AC_move_entry((H5F_t *)f, H5AC_FHEAP_DBLOCK, hdr->man_dtable.table_addr, dblock_addr) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
 
-    if(destroy)
-        if(H5HF_cache_dblock_dest(f, dblock) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap direct block")
+                /* Update information about direct block's location */
+                hdr->man_dtable.table_addr = dblock_addr;
 
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* H5HF_cache_dblock_flush() */
+                /* Mark that heap header was modified */
+                if(H5HF_hdr_dirty(hdr) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
+            } /* end if */
+            else { /* the direct block's parent is an indirect block */
+                /* Sanity check */
+                HDassert(par_iblock);
+                HDassert(H5F_addr_eq(par_iblock->ents[par_entry].addr, addr));
 
-
-/*-------------------------------------------------------------------------
- * Function:	H5HF_cache_dblock_dest
- *
- * Purpose:	Destroys a fractal heap direct block in memory.
- *
- * Return:	Non-negative on success/Negative on failure
- *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 27 2006
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5HF_cache_dblock_dest(H5F_t *f, H5HF_direct_t *dblock)
-{
-    herr_t      ret_value = SUCCEED;    /* Return value */
+                /* Allocate 'normal' space for the direct block */
+                if(HADDR_UNDEF == (dblock_addr = H5MF_alloc((H5F_t *)f, H5FD_MEM_FHEAP_DBLOCK, dxpl_id, (hsize_t)write_size)))
+                    HGOTO_ERROR(H5E_HEAP, H5E_NOSPACE, FAIL, "file allocation failed for fractal heap direct block")
 
-    FUNC_ENTER_NOAPI_NOINIT
+                /* Sanity check */
+                HDassert(!H5F_addr_eq(par_iblock->ents[par_entry].addr, dblock_addr));
 
-    /*
-     * Check arguments.
-     */
-    HDassert(dblock);
+                /* Let the metadata cache know the block moved */
+                if(H5AC_move_entry((H5F_t *)f, H5AC_FHEAP_DBLOCK, par_iblock->ents[par_entry].addr, dblock_addr) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTMOVE, FAIL, "unable to move direct block")
 
-    /* If we're going to free the space on disk, the address must be valid */
-    HDassert(!dblock->cache_info.free_file_space_on_destroy || H5F_addr_defined(dblock->cache_info.addr));
+                /* Update information about direct block's location */
+                par_iblock->ents[par_entry].addr = dblock_addr;
 
-    /* Check for freeing file space for direct block */
-    if(dblock->cache_info.free_file_space_on_destroy) {
-        /* Sanity check */
-        HDassert(dblock->file_size > 0);
-
-        /* Check if the direct block is NOT currently allocated in temp. file space */
-        /* (temp. file space does not need to be freed) */
-        if(!H5F_IS_TMP_ADDR(f, dblock->cache_info.addr)) {
-            /* Release the space on disk */
-            /* (XXX: Nasty usage of internal DXPL value! -QAK) */
-            if(H5MF_xfree(f, H5FD_MEM_FHEAP_DBLOCK, H5AC_dxpl_id, dblock->cache_info.addr, dblock->file_size) < 0)
-                HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to free fractal heap direct block")
+                /* Mark that parent was modified */
+                if(H5HF_iblock_dirty(par_iblock) < 0)
+                    HGOTO_ERROR(H5E_HEAP, H5E_CANTDIRTY, FAIL, "can't mark heap header as dirty")
+            } /* end else */
         } /* end if */
+    } /* end else */
+
+    /* At this point, write_buf points to a buffer containing the image 
+     * of the direct block that is ready to copy into the image buffer,
+     * and write_size contains the length of this buffer. 
+     *
+     * Also, if image size or address has changed, the direct block's
+     * parent has been modified to reflect the change.
+     *
+     * Now, make note of the pointer and length of the above buffer for
+     * use by the serialize function.
+     */
+    dblock->write_buf = (uint8_t *)write_buf;
+    dblock->write_size = write_size;
+
+    /* finally, pass data back to the metadata cache as appropriate */
+    if(!H5F_addr_eq(addr, dblock_addr)) {
+        dblock_flags |= H5C__SERIALIZE_MOVED_FLAG;
+        *new_addr = dblock_addr;
     } /* end if */
 
-    /* Destroy fractal heap direct block */
-    if(H5HF_man_dblock_dest(dblock) < 0)
-        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap direct block")
+    if((hdr->filter_len > 0) && (compressed_len != write_size)) {
+        dblock_flags |= H5C__SERIALIZE_COMPRESSED_FLAG;
+        *new_compressed_len = write_size;
+    } /* end if */
+
+    *flags = dblock_flags;
+
+    /* final sanity check */
+    HDassert(dblock->write_buf);
+    HDassert(dblock->write_size > 0);
 
 done:
+    /* discard the write buf if we have an error */
+    if(write_buf && (write_buf != dblock->blk) && (dblock->write_buf == NULL))
+	H5MM_xfree(write_buf);
+
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_dblock_dest() */
+} /* end H5HF__cache_dblock_pre_serialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_dblock_clear
+ * Function:	H5HF__cache_dblock_serialize
  *
- * Purpose:	Mark a fractal heap direct block in memory as non-dirty.
+ * Purpose:	In principle, this function is supposed to construct the on 
+ *		disk image of the direct block, and place that image in the 
+ *		image buffer provided by the metadata cache.
  *
- * Return:	Non-negative on success/Negative on failure
+ *		However, since there are cases in which the pre_serialize 
+ *		function has to construct the on disk image to determine its size 
+ *		and address, this function simply copies the image prepared by
+ *		the pre-serialize function into the supplied image buffer, and 
+ *		discards a buffer if necessary.
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 27 2006
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_dblock_clear(H5F_t *f, H5HF_direct_t *dblock, hbool_t destroy)
+static herr_t 
+H5HF__cache_dblock_serialize(const H5F_t *f, void *image, size_t len,
+    void *_thing)
 {
-    herr_t ret_value = SUCCEED;         /* Return value */
+    H5HF_direct_t       *dblock = (H5HF_direct_t *)_thing;      /* Direct block info */
+    herr_t               ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC_NOERR
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
+    HDassert(f);
+    HDassert(image);
+    HDassert(len > 0);
     HDassert(dblock);
+    HDassert(dblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(dblock->cache_info.type == H5AC_FHEAP_DBLOCK);
+    HDassert((dblock->blk != dblock->write_buf) || (dblock->cache_info.size == dblock->size));
+    HDassert(dblock->write_buf);
+    HDassert(dblock->write_size > 0);
+    HDassert((dblock->blk != dblock->write_buf) || (dblock->write_size == dblock->size));
+    HDassert(dblock->write_size == len);
+
+    /* Copy the image from *(dblock->write_buf) to *image */
+    HDmemcpy(image, dblock->write_buf, dblock->write_size);
+
+    /* Free *(dblock->write_buf) if it was allocated by the 
+     * pre-serialize function 
+     */
+    if(dblock->write_buf != dblock->blk)
+        H5MM_xfree(dblock->write_buf);
 
-    /* Reset the dirty flag.  */
-    dblock->cache_info.is_dirty = FALSE;
-
-    if(destroy)
-        if(H5HF_cache_dblock_dest(f, dblock) < 0)
-	    HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap direct block")
+    /* Reset the write_buf and write_size fields */
+    dblock->write_buf = NULL;
+    dblock->write_size = 0;
 
-done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_dblock_clear() */
+} /* end H5HF__cache_dblock_serialize() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_dblock_notify
+ * Function:	H5HF__cache_dblock_notify
  *
  * Purpose:	Setup / takedown flush dependencies as direct blocks
  *		are loaded / inserted and evicted from the metadata cache.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
  *
  * Programmer:	John Mainzer
- *		5/17/14
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_dblock_notify(H5C_notify_action_t action, H5HF_direct_t *dblock)
+static herr_t 
+H5HF__cache_dblock_notify(H5C_notify_action_t action, void *_thing)
 {
-    herr_t ret_value = SUCCEED;         /* Return value */
+    H5HF_direct_t 	*dblock = (H5HF_direct_t *)_thing;      /* Fractal heap direct block */
+    herr_t 		 ret_value = SUCCEED;         /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
-    /*
-     * Check arguments.
-     */
+    /* Sanity checks */
     HDassert(dblock);
     HDassert(dblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_MAGIC);
+    HDassert(dblock->cache_info.type == H5AC_FHEAP_DBLOCK);
     HDassert(dblock->hdr);
     HDassert((dblock->fd_parent) ||
              ((dblock->hdr->man_dtable.curr_root_rows == 0) && (dblock->block_off == (hsize_t)0)));
 
     switch(action) {
         case H5AC_NOTIFY_ACTION_AFTER_INSERT:
+        case H5AC_NOTIFY_ACTION_AFTER_LOAD:
             HDassert(dblock->parent == dblock->fd_parent);
             if(dblock->parent) {        /* this is a leaf dblock */
                 /* create flush dependency with parent iblock */
@@ -1964,6 +2392,10 @@ H5HF_cache_dblock_notify(H5C_notify_action_t action, H5HF_direct_t *dblock)
             } /* end else */
             break;
 
+	case H5AC_NOTIFY_ACTION_AFTER_FLUSH:
+	    /* do nothing */
+	    break;
+
         case H5AC_NOTIFY_ACTION_BEFORE_EVICT:
             HDassert((dblock->parent == dblock->fd_parent) ||
                      ((NULL == dblock->parent) && (dblock->fd_parent)));
@@ -1986,39 +2418,47 @@ H5HF_cache_dblock_notify(H5C_notify_action_t action, H5HF_direct_t *dblock)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5HF_cache_dblock_notify() */
+} /* end H5HF__cache_dblock_notify() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_cache_dblock_size
+ * Function:	H5HF__cache_dblock_free_icr
  *
- * Purpose:	Compute the size in bytes of a fractal heap direct block
- *		on disk, and return it in *size_ptr.  On failure,
- *		the value of *size_ptr is undefined.
+ * Purpose:	Free the in core memory allocated to the supplied direct
+ *		block.
  *
- * Return:	Non-negative on success/Negative on failure
+ * Note:	The metadata cache sets the object's cache_info.magic to
+ *		H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC before calling a free_icr
+ *		callback (checked in assert).
  *
- * Programmer:	Quincey Koziol
- *		koziol@ncsa.uiuc.edu
- *		Feb 24 2006
+ * Return:	Success:	SUCCEED
+ *		Failure:	FAIL
+ *
+ * Programmer:	John Mainzer
+ *		6/21/14
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5HF_cache_dblock_size(const H5F_t H5_ATTR_UNUSED *f, const H5HF_direct_t *dblock, size_t *size_ptr)
+static herr_t 
+H5HF__cache_dblock_free_icr(void *_thing)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    H5HF_direct_t       *dblock = (H5HF_direct_t *)_thing;      /* Fractal heap direct block */
+    herr_t      	 ret_value = SUCCEED;    /* Return value */
 
-    /* check arguments */
-    HDassert(dblock);
-    HDassert(size_ptr);
+    FUNC_ENTER_STATIC
 
-    /* Set size value */
-    *size_ptr = dblock->size;
+    /* Sanity checks */
+    HDassert(dblock);
+    HDassert(dblock->cache_info.magic == H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC);
+    HDassert(dblock->cache_info.type == H5AC_FHEAP_DBLOCK);
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_cache_dblock_size() */
+    /* Destroy fractal heap direct block */
+    if(H5HF_man_dblock_dest(dblock) < 0)
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTFREE, FAIL, "unable to destroy fractal heap direct block")
 
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5HF__cache_dblock_free_icr() */
 
 
 /*------------------------------------------------------------------------
@@ -2144,7 +2584,7 @@ H5HF__cache_verify_hdr_descendants_clean(H5F_t *f, hid_t dxpl_id,
                      * in this case, since we know that the entry is in cache,
                      * we can pass NULL udata.
 		     */
-                    if(NULL == (root_iblock = (H5HF_indirect_t *)H5AC_protect(f, dxpl_id, H5AC_FHEAP_IBLOCK, root_iblock_addr, NULL, H5AC_READ)))
+                    if(NULL == (root_iblock = (H5HF_indirect_t *)H5AC_protect(f, dxpl_id, H5AC_FHEAP_IBLOCK, root_iblock_addr, NULL, H5C__READ_ONLY_FLAG)))
                         HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "H5AC_protect() faild.")
                     unprotect_root_iblock = TRUE;
 		} /* end if */
@@ -2205,7 +2645,7 @@ H5HF__cache_verify_hdr_descendants_clean(H5F_t *f, hid_t dxpl_id,
                      * in this case, since we know that the entry is in cache,
                      * we can pass NULL udata.
                      */
-                    if(NULL == (iblock = (H5HF_indirect_t *)H5AC_protect(f, dxpl_id, H5AC_FHEAP_IBLOCK, root_iblock_addr, NULL, H5AC_READ)))
+                    if(NULL == (iblock = (H5HF_indirect_t *)H5AC_protect(f, dxpl_id, H5AC_FHEAP_IBLOCK, root_iblock_addr, NULL, H5C__READ_ONLY_FLAG)))
                         HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "H5AC_protect() faild.")
                     unprotect_root_iblock = TRUE;
                     HDassert(iblock == root_iblock);
@@ -2595,7 +3035,7 @@ H5HF__cache_verify_descendant_iblocks_clean(H5F_t *f, hid_t dxpl_id,
 			    /* in this case, since we know that the      */
 			    /* entry is in cache, we can pass NULL udata */
 
-			    if(NULL == (child_iblock = (H5HF_indirect_t *) H5AC_protect(f, dxpl_id, H5AC_FHEAP_IBLOCK, child_iblock_addr, NULL, H5AC_READ)))
+			    if(NULL == (child_iblock = (H5HF_indirect_t *) H5AC_protect(f, dxpl_id, H5AC_FHEAP_IBLOCK, child_iblock_addr, NULL, H5C__READ_ONLY_FLAG)))
                                 HGOTO_ERROR(H5E_HEAP, H5E_CANTPROTECT, FAIL, "H5AC_protect() faild.")
 			    unprotect_child_iblock = TRUE;
 			} /* end if */