[svn-r17943] Description:

	Finish refactoring v2 B-trees so that they can have client callback
context provided to the encode/decode callbacks.

Tested on:
        FreeBSD/32 6.3 (duty) in debug mode
        FreeBSD/64 6.3 (liberty) w/C++ & FORTRAN, in debug mode
        Linux/32 2.6 (jam) w/PGI compilers, w/default API=1.8.x,
                w/C++ & FORTRAN, w/threadsafe, in debug mode
        Linux/64-amd64 2.6 (smirom) w/Intel compilers, w/default API=1.6.x,
                w/C++ & FORTRAN, in production mode
        Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
                w/szip filter, in production mode
        Linux/64-ia64 2.6 (cobalt) w/Intel compilers, w/C++ & FORTRAN,
                in production mode
        Linux/64-ia64 2.4 (tg-login3) w/parallel, w/FORTRAN, in debug mode
        Linux/64-amd64 2.6 (abe) w/parallel, w/FORTRAN, in production mode
        Mac OS X/32 10.6.2 (amazon) in debug mode
        Mac OS X/32 10.6.2 (amazon) w/C++ & FORTRAN, w/threadsafe,
                in production mode

29 files changed, 1252 insertions, 647 deletions

diff --git a/src/H5Abtree2.c b/src/H5Abtree2.c
index 7d0bb4c..eb2c741 100644
--- a/src/H5Abtree2.c
+++ b/src/H5Abtree2.c
@@ -81,20 +81,20 @@ typedef struct H5A_fh_ud_cmp_t {
 /* v2 B-tree driver callbacks for 'creation order' index */
 static herr_t H5A_dense_btree2_corder_store(void *native, const void *udata);
 static herr_t H5A_dense_btree2_corder_compare(const void *rec1, const void *rec2);
-static herr_t H5A_dense_btree2_corder_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5A_dense_btree2_corder_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
+static herr_t H5A_dense_btree2_corder_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5A_dense_btree2_corder_decode(const uint8_t *raw, void *native,
+    void *ctx);
 static herr_t H5A_dense_btree2_corder_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
 /* v2 B-tree driver callbacks for 'name' index */
 static herr_t H5A_dense_btree2_name_store(void *native, const void *udata);
 static herr_t H5A_dense_btree2_name_compare(const void *rec1, const void *rec2);
-static herr_t H5A_dense_btree2_name_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5A_dense_btree2_name_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
+static herr_t H5A_dense_btree2_name_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5A_dense_btree2_name_decode(const uint8_t *raw, void *native,
+    void *ctx);
 static herr_t H5A_dense_btree2_name_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
@@ -110,11 +110,15 @@ const H5B2_class_t H5A_BT2_NAME[1]={{  /* B-tree class information */
     H5B2_ATTR_DENSE_NAME_ID,           /* Type of B-tree */
     "H5B2_ATTR_DENSE_NAME_ID",         /* Name of B-tree class */
     sizeof(H5A_dense_bt2_name_rec_t),  /* Size of native record */
+    NULL,                              /* Create client callback context */
+    NULL,                              /* Destroy client callback context */
     H5A_dense_btree2_name_store,       /* Record storage callback */
     H5A_dense_btree2_name_compare,     /* Record comparison callback */
     H5A_dense_btree2_name_encode,      /* Record encoding callback */
     H5A_dense_btree2_name_decode,      /* Record decoding callback */
-    H5A_dense_btree2_name_debug        /* Record debugging callback */
+    H5A_dense_btree2_name_debug,       /* Record debugging callback */
+    NULL,                              /* Create debugging context */
+    NULL                               /* Destroy debugging context */
 }};
 
 /* v2 B-tree class for indexing 'creation order' field of attributes */
@@ -122,11 +126,15 @@ const H5B2_class_t H5A_BT2_CORDER[1]={{ /* B-tree class information */
     H5B2_ATTR_DENSE_CORDER_ID,         /* Type of B-tree */
     "H5B2_ATTR_DENSE_CORDER_ID",       /* Name of B-tree class */
     sizeof(H5A_dense_bt2_corder_rec_t),/* Size of native record */
+    NULL,                              /* Create client callback context */
+    NULL,                              /* Destroy client callback context */
     H5A_dense_btree2_corder_store,     /* Record storage callback */
     H5A_dense_btree2_corder_compare,   /* Record comparison callback */
     H5A_dense_btree2_corder_encode,    /* Record encoding callback */
     H5A_dense_btree2_corder_decode,    /* Record decoding callback */
-    H5A_dense_btree2_corder_debug      /* Record debugging callback */
+    H5A_dense_btree2_corder_debug,     /* Record debugging callback */
+    NULL,                              /* Create debugging context */
+    NULL                               /* Destroy debugging context */
 }};
 
 
@@ -311,7 +319,7 @@ H5A_dense_btree2_name_compare(const void *_bt2_udata, const void *_bt2_rec)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5A_dense_btree2_name_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_nrecord)
+H5A_dense_btree2_name_encode(uint8_t *raw, const void *_nrecord, void UNUSED *ctx)
 {
     const H5A_dense_bt2_name_rec_t *nrecord = (const H5A_dense_bt2_name_rec_t *)_nrecord;
 
@@ -341,7 +349,7 @@ H5A_dense_btree2_name_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_n
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5A_dense_btree2_name_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_nrecord)
+H5A_dense_btree2_name_decode(const uint8_t *raw, void *_nrecord, void UNUSED *ctx)
 {
     H5A_dense_bt2_name_rec_t *nrecord = (H5A_dense_bt2_name_rec_t *)_nrecord;
 
@@ -469,7 +477,7 @@ H5A_dense_btree2_corder_compare(const void *_bt2_udata, const void *_bt2_rec)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5A_dense_btree2_corder_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_nrecord)
+H5A_dense_btree2_corder_encode(uint8_t *raw, const void *_nrecord, void UNUSED *ctx)
 {
     const H5A_dense_bt2_corder_rec_t *nrecord = (const H5A_dense_bt2_corder_rec_t *)_nrecord;
 
@@ -498,7 +506,7 @@ H5A_dense_btree2_corder_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5A_dense_btree2_corder_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_nrecord)
+H5A_dense_btree2_corder_decode(const uint8_t *raw, void *_nrecord, void UNUSED *ctx)
 {
     H5A_dense_bt2_corder_rec_t *nrecord = (H5A_dense_bt2_corder_rec_t *)_nrecord;
 
diff --git a/src/H5Adense.c b/src/H5Adense.c
index c9da207..889889e 100644
--- a/src/H5Adense.c
+++ b/src/H5Adense.c
@@ -246,7 +246,7 @@ HDfprintf(stderr, "%s: fheap_id_len = %Zu\n", FUNC, fheap_id_len);
             H5O_FHEAP_ID_LEN;           /* Fractal heap ID */
     bt2_cparam.split_percent = H5A_NAME_BT2_SPLIT_PERC;
     bt2_cparam.merge_percent = H5A_NAME_BT2_MERGE_PERC;
-    if(NULL == (bt2_name = H5B2_create(f, dxpl_id, &bt2_cparam)))
+    if(NULL == (bt2_name = H5B2_create(f, dxpl_id, &bt2_cparam, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, FAIL, "unable to create v2 B-tree for name index")
 
     /* Retrieve the v2 B-tree's address in the file */
@@ -267,7 +267,7 @@ HDfprintf(stderr, "%s: ainfo->name_bt2_addr = %a\n", FUNC, ainfo->name_bt2_addr)
                 H5O_FHEAP_ID_LEN;       /* Fractal heap ID */
         bt2_cparam.split_percent = H5A_CORDER_BT2_SPLIT_PERC;
         bt2_cparam.merge_percent = H5A_CORDER_BT2_MERGE_PERC;
-        if(NULL == (bt2_corder = H5B2_create(f, dxpl_id, &bt2_cparam)))
+        if(NULL == (bt2_corder = H5B2_create(f, dxpl_id, &bt2_cparam, NULL)))
             HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, FAIL, "unable to create v2 B-tree for creation order index")
 
         /* Retrieve the v2 B-tree's address in the file */
@@ -383,7 +383,7 @@ H5A_dense_open(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, const char *na
     } /* end if */
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, NULL, "unable to open v2 B-tree for name index")
 
     /* Create the "udata" information for v2 B-tree record find */
@@ -528,7 +528,7 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, H5A_t *attr)
     } /* end else */
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Create the callback information for v2 B-tree record insertion */
@@ -552,7 +552,7 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, H5A_t *attr)
     if(ainfo->index_corder) {
         /* Open the creation order index v2 B-tree */
         HDassert(H5F_addr_defined(ainfo->corder_bt2_addr));
-        if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, ainfo->corder_bt2_addr)))
+        if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, ainfo->corder_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
         /* Insert the record into the creation order index v2 B-tree */
@@ -660,7 +660,7 @@ H5A_dense_write_bt2_cb(void *_record, void *_op_data, hbool_t *changed)
             H5A_bt2_ud_common_t udata;          /* User data for v2 B-tree modify */
 
             /* Open the creation order index v2 B-tree */
-            if(NULL == (bt2_corder = H5B2_open(op_data->f, op_data->dxpl_id, op_data->corder_bt2_addr)))
+            if(NULL == (bt2_corder = H5B2_open(op_data->f, op_data->dxpl_id, op_data->corder_bt2_addr, NULL)))
                 HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
             /* Create the "udata" information for v2 B-tree record modify */
@@ -790,7 +790,7 @@ H5A_dense_write(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, H5A_t *attr)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Create the "udata" information for v2 B-tree record modify */
@@ -936,7 +936,7 @@ H5A_dense_rename(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, const char *
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Create the "udata" information for v2 B-tree record modify */
@@ -1215,7 +1215,7 @@ H5A_dense_iterate(H5F_t *f, hid_t dxpl_id, hid_t loc_id, const H5O_ainfo_t *ainf
         } /* end if */
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr, NULL)))
             HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Construct the user data for v2 B-tree iterator callback */
@@ -1291,7 +1291,7 @@ H5A_dense_remove_bt2_cb(const void *_record, void *_udata)
     /* Check for removing the link from the creation order index */
     if(H5F_addr_defined(udata->corder_bt2_addr)) {
         /* Open the creation order index v2 B-tree */
-        if(NULL == (bt2_corder = H5B2_open(udata->common.f, udata->common.dxpl_id, udata->corder_bt2_addr)))
+        if(NULL == (bt2_corder = H5B2_open(udata->common.f, udata->common.dxpl_id, udata->corder_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
         /* Set up the user data for the v2 B-tree 'record remove' callback */
@@ -1386,7 +1386,7 @@ H5A_dense_remove(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, const char *
     } /* end if */
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Set up the user data for the v2 B-tree 'record remove' callback */
@@ -1500,7 +1500,7 @@ H5A_dense_remove_by_idx_bt2_cb(const void *_record, void *_bt2_udata)
         } /* end else */
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(bt2_udata->f, bt2_udata->dxpl_id, bt2_udata->other_bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(bt2_udata->f, bt2_udata->dxpl_id, bt2_udata->other_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Set the common information for the v2 B-tree remove operation */
@@ -1632,7 +1632,7 @@ H5A_dense_remove_by_idx(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo,
         } /* end if */
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr, NULL)))
             HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Set up the user data for the v2 B-tree 'record remove' callback */
@@ -1735,7 +1735,7 @@ H5A_dense_exists(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo, const char *
     } /* end if */
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Create the "udata" information for v2 B-tree record 'find' */
@@ -1876,7 +1876,7 @@ H5A_dense_delete(H5F_t *f, hid_t dxpl_id, H5O_ainfo_t *ainfo)
     udata.found_op_data = NULL;
 
     /* Delete name index v2 B-tree */
-    if(H5B2_delete(f, dxpl_id, ainfo->name_bt2_addr, H5A_dense_delete_bt2_cb, &udata) < 0)
+    if(H5B2_delete(f, dxpl_id, ainfo->name_bt2_addr, NULL, H5A_dense_delete_bt2_cb, &udata) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree for name index")
     ainfo->name_bt2_addr = HADDR_UNDEF;
 
@@ -1888,7 +1888,7 @@ H5A_dense_delete(H5F_t *f, hid_t dxpl_id, H5O_ainfo_t *ainfo)
     /* Check if we should delete the creation order index v2 B-tree */
     if(H5F_addr_defined(ainfo->corder_bt2_addr)) {
         /* Delete the creation order index, without adjusting the ref. count on the attributes  */
-        if(H5B2_delete(f, dxpl_id, ainfo->corder_bt2_addr, NULL, NULL) < 0)
+        if(H5B2_delete(f, dxpl_id, ainfo->corder_bt2_addr, NULL, NULL, NULL) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree for creation order index")
         ainfo->corder_bt2_addr = HADDR_UNDEF;
     } /* end if */
diff --git a/src/H5Aint.c b/src/H5Aint.c
index ab1d32c..c50126a 100644
--- a/src/H5Aint.c
+++ b/src/H5Aint.c
@@ -328,7 +328,7 @@ H5A_dense_build_table(H5F_t *f, hid_t dxpl_id, const H5O_ainfo_t *ainfo,
     HDassert(atable);
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Retrieve # of records in "name" B-tree */
@@ -724,7 +724,7 @@ H5A_get_ainfo(H5F_t *f, hid_t dxpl_id, H5O_t *oh, H5O_ainfo_t *ainfo)
             /* Check if we are using "dense" attribute storage */
             if(H5F_addr_defined(ainfo->fheap_addr)) {
                 /* Open the name index v2 B-tree */
-                if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr)))
+                if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo->name_bt2_addr, NULL)))
                     HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
                 /* Retrieve # of records in "name" B-tree */
diff --git a/src/H5B2.c b/src/H5B2.c
index b6e8392..5ab9e8a 100644
--- a/src/H5B2.c
+++ b/src/H5B2.c
@@ -73,10 +73,10 @@
  * client class..
  */
 extern const H5B2_class_t H5B2_TEST[1];
-extern const H5B2_class_t H5HF_BT2_INDIR[1];
-extern const H5B2_class_t H5HF_BT2_FILT_INDIR[1];
-extern const H5B2_class_t H5HF_BT2_DIR[1];
-extern const H5B2_class_t H5HF_BT2_FILT_DIR[1];
+extern const H5B2_class_t H5HF_HUGE_BT2_INDIR[1];
+extern const H5B2_class_t H5HF_HUGE_BT2_FILT_INDIR[1];
+extern const H5B2_class_t H5HF_HUGE_BT2_DIR[1];
+extern const H5B2_class_t H5HF_HUGE_BT2_FILT_DIR[1];
 extern const H5B2_class_t H5G_BT2_NAME[1];
 extern const H5B2_class_t H5G_BT2_CORDER[1];
 extern const H5B2_class_t H5SM_INDEX[1];
@@ -85,10 +85,10 @@ extern const H5B2_class_t H5A_BT2_CORDER[1];
 
 const H5B2_class_t *const H5B2_client_class_g[] = {
     H5B2_TEST,			/* 0 - H5B2_TEST_ID 			*/
-    H5HF_BT2_INDIR,		/* 1 - H5B2_FHEAP_HUGE_INDIR_ID 	*/
-    H5HF_BT2_FILT_INDIR,	/* 2 - H5B2_FHEAP_HUGE_FILT_INDIR_ID 	*/
-    H5HF_BT2_DIR,		/* 3 - H5B2_FHEAP_HUGE_DIR_ID 		*/
-    H5HF_BT2_FILT_DIR,		/* 4 - H5B2_FHEAP_HUGE_FILT_DIR_ID 	*/
+    H5HF_HUGE_BT2_INDIR,	/* 1 - H5B2_FHEAP_HUGE_INDIR_ID 	*/
+    H5HF_HUGE_BT2_FILT_INDIR,	/* 2 - H5B2_FHEAP_HUGE_FILT_INDIR_ID 	*/
+    H5HF_HUGE_BT2_DIR,		/* 3 - H5B2_FHEAP_HUGE_DIR_ID 		*/
+    H5HF_HUGE_BT2_FILT_DIR,	/* 4 - H5B2_FHEAP_HUGE_FILT_DIR_ID 	*/
     H5G_BT2_NAME,		/* 5 - H5B2_GRP_DENSE_NAME_ID 		*/
     H5G_BT2_CORDER,		/* 6 - H5B2_GRP_DENSE_CORDER_ID 		*/
     H5SM_INDEX,			/* 7 - H5B2_SOHM_INDEX_ID 		*/
@@ -126,7 +126,7 @@ H5FL_DEFINE_STATIC(H5B2_t);
  *-------------------------------------------------------------------------
  */
 H5B2_t *
-H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam)
+H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam, void *ctx_udata)
 {
     H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
     H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
@@ -145,7 +145,7 @@ H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam)
     HDcompile_assert(H5B2_NUM_BTREE_ID == NELMTS(H5B2_client_class_g));
 
     /* Create shared v2 B-tree header */
-    if(HADDR_UNDEF == (hdr_addr = H5B2_hdr_create(f, dxpl_id, cparam)))
+    if(HADDR_UNDEF == (hdr_addr = H5B2_hdr_create(f, dxpl_id, cparam, ctx_udata)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, NULL, "can't create v2 B-tree header")
 
     /* Create v2 B-tree wrapper */
@@ -153,7 +153,7 @@ H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam)
         HGOTO_ERROR(H5E_BTREE, H5E_CANTALLOC, NULL, "memory allocation failed for v2 B-tree info")
 
     /* Look up the B-tree header */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, NULL, NULL, H5AC_WRITE)))
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, NULL, ctx_udata, H5AC_WRITE)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTPROTECT, NULL, "unable to load B-tree header")
 
     /* Point v2 B-tree wrapper at header and bump it's ref count */
@@ -197,7 +197,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5B2_t *
-H5B2_open(H5F_t *f, hid_t dxpl_id, haddr_t addr)
+H5B2_open(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *ctx_udata)
 {
     H5B2_t	*bt2 = NULL;            /* Pointer to the B-tree */
     H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
@@ -210,7 +210,7 @@ H5B2_open(H5F_t *f, hid_t dxpl_id, haddr_t addr)
     HDassert(H5F_addr_defined(addr));
 
     /* Look up the B-tree header */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, NULL, NULL, H5AC_READ)))
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, NULL, ctx_udata, H5AC_READ)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTPROTECT, NULL, "unable to load B-tree header")
 
     /* Check for pending heap deletion */
@@ -1140,13 +1140,6 @@ H5B2_close(H5B2_t *bt2, hid_t dxpl_id)
         } /* end if */
     } /* end if */
 
-    /* Decrement the reference count on the B-tree header */
-    /* (don't put in H5B2_hdr_fuse_decr() as the B-tree header may be evicted
-     *  immediately -QAK)
-     */
-    if(H5B2_hdr_decr(bt2->hdr) < 0)
-        HGOTO_ERROR(H5E_BTREE, H5E_CANTDEC, FAIL, "can't decrement reference count on shared v2 B-tree header")
-
     /* Check for pending v2 B-tree deletion */
     if(pending_delete) {
         H5B2_hdr_t *hdr;            /* Another pointer to v2 B-tree header */
@@ -1154,17 +1147,49 @@ H5B2_close(H5B2_t *bt2, hid_t dxpl_id)
         /* Sanity check */
         HDassert(H5F_addr_defined(bt2_addr));
 
+#ifndef NDEBUG
+{
+    unsigned hdr_status = 0;         /* Header's status in the metadata cache */
+
+    /* Check the header's status in the metadata cache */
+    if(H5AC_get_entry_status(bt2->f, bt2_addr, &hdr_status) < 0)
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTGET, FAIL, "unable to check metadata cache status for v2 B-tree header, address = %llu", (unsigned long long)bt2_addr)
+
+    /* Sanity checks on header */
+    HDassert(hdr_status & H5AC_ES__IN_CACHE);
+    HDassert(hdr_status & H5AC_ES__IS_PINNED);
+    HDassert(!(hdr_status & H5AC_ES__IS_PROTECTED));
+}
+#endif /* NDEBUG */
+
         /* Lock the v2 B-tree header into memory */
+        /* (OK to pass in NULL for callback context, since we know the header must be in the cache) */
         if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(bt2->f, dxpl_id, H5AC_BT2_HDR, bt2_addr, NULL, NULL, H5AC_WRITE)))
             HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load v2 B-tree header")
 
         /* Set the shared v2 B-tree header's file context for this operation */
         hdr->f = bt2->f;
 
+        /* Decrement the reference count on the B-tree header */
+        /* (don't put in H5B2_hdr_fuse_decr() as the B-tree header may be evicted
+         *  immediately -QAK)
+         */
+        if(H5B2_hdr_decr(bt2->hdr) < 0)
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTDEC, FAIL, "can't decrement reference count on shared v2 B-tree header")
+
         /* Delete v2 B-tree, starting with header (unprotects header) */
         if(H5B2_hdr_delete(hdr, dxpl_id) < 0)
             HGOTO_ERROR(H5E_BTREE, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree")
     } /* end if */
+    else {
+        /* Decrement the reference count on the B-tree header */
+        /* (don't put in H5B2_hdr_fuse_decr() as the B-tree header may be evicted
+         *  immediately -QAK)
+         */
+        if(H5B2_hdr_decr(bt2->hdr) < 0)
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTDEC, FAIL, "can't decrement reference count on shared v2 B-tree header")
+
+    } /* end else */
 
     /* Release the v2 B-tree wrapper */
     bt2 = H5FL_FREE(H5B2_t, bt2);
@@ -1197,8 +1222,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5B2_delete(H5F_t *f, hid_t dxpl_id, haddr_t addr, H5B2_remove_t op,
-    void *op_data)
+H5B2_delete(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *ctx_udata,
+    H5B2_remove_t op, void *op_data)
 {
     H5B2_hdr_t	*hdr = NULL;            /* Pointer to the B-tree header */
     herr_t	ret_value = SUCCEED;    /* Return value */
@@ -1213,8 +1238,8 @@ H5B2_delete(H5F_t *f, hid_t dxpl_id, haddr_t addr, H5B2_remove_t op,
 #ifdef QAK
 HDfprintf(stderr, "%s: addr = %a\n", FUNC, addr);
 #endif /* QAK */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, NULL, NULL, H5AC_WRITE)))
-        HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load v2 B-tree header")
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, NULL, ctx_udata, H5AC_WRITE)))
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTPROTECT, FAIL, "unable to protect v2 B-tree header")
 
     /* Remember the callback & context for later */
     hdr->remove_op = op;
diff --git a/src/H5B2cache.c b/src/H5B2cache.c
index 6737076..15dcb26 100644
--- a/src/H5B2cache.c
+++ b/src/H5B2cache.c
@@ -147,7 +147,8 @@ const H5AC_class_t H5AC_BT2_LEAF[1] = {{
  *-------------------------------------------------------------------------
  */
 static H5B2_hdr_t *
-H5B2_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *udata1, void UNUSED *udata2)
+H5B2_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *udata1,
+    void *ctx_udata)
 {
     H5B2_create_t       cparam;         /* B-tree creation parameters */
     H5B2_subid_t        id;		/* ID of B-tree class, as found in file */
@@ -237,7 +238,7 @@ H5B2_cache_hdr_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *ud
 
     /* Initialize B-tree header info */
     cparam.cls = H5B2_client_class_g[id];
-    if(H5B2_hdr_init(f, hdr, &cparam, depth) < 0)
+    if(H5B2_hdr_init(f, hdr, &cparam, ctx_udata, depth) < 0)
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, NULL, "can't initialize B-tree header info")
 
     /* Set the B-tree header's address */
@@ -564,7 +565,7 @@ H5B2_cache_internal_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_uda
     native = internal->int_native;
     for(u = 0; u < internal->nrec; u++) {
         /* Decode record */
-        if((udata->hdr->cls->decode)(f, p, native) < 0)
+        if((udata->hdr->cls->decode)(p, native, udata->hdr->cb_ctx) < 0)
             HGOTO_ERROR(H5E_BTREE, H5E_CANTDECODE, NULL, "unable to decode B-tree record")
 
         /* Move to next record */
@@ -663,7 +664,7 @@ H5B2_cache_internal_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr
         native = internal->int_native;
         for(u = 0; u < internal->nrec; u++) {
             /* Encode record */
-            if((internal->hdr->cls->encode)(f, p, native) < 0)
+            if((internal->hdr->cls->encode)(p, native, internal->hdr->cb_ctx) < 0)
                 HGOTO_ERROR(H5E_BTREE, H5E_CANTENCODE, FAIL, "unable to encode B-tree record")
 
             /* Move to next record */
@@ -916,7 +917,7 @@ H5B2_cache_leaf_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_nrec, v
     native = leaf->leaf_native;
     for(u = 0; u < leaf->nrec; u++) {
         /* Decode record */
-        if((hdr->cls->decode)(f, p, native) < 0)
+        if((hdr->cls->decode)(p, native, hdr->cb_ctx) < 0)
             HGOTO_ERROR(H5E_BTREE, H5E_CANTENCODE, NULL, "unable to decode B-tree record")
 
         /* Move to next record */
@@ -999,7 +1000,7 @@ H5B2_cache_leaf_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5
         native = leaf->leaf_native;
         for(u = 0; u < leaf->nrec; u++) {
             /* Encode record */
-            if((leaf->hdr->cls->encode)(f, p, native) < 0)
+            if((leaf->hdr->cls->encode)(p, native, leaf->hdr->cb_ctx) < 0)
                 HGOTO_ERROR(H5E_BTREE, H5E_CANTENCODE, FAIL, "unable to encode B-tree record")
 
             /* Move to next record */
diff --git a/src/H5B2dbg.c b/src/H5B2dbg.c
index 17a64cd..f8a1fc9 100644
--- a/src/H5B2dbg.c
+++ b/src/H5B2dbg.c
@@ -91,6 +91,7 @@ H5B2_hdr_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     const H5B2_class_t *type)
 {
     H5B2_hdr_t	*hdr = NULL;            /* B-tree header info */
+    void        *dbg_ctx = NULL;	/* v2 B-tree debugging context */
     unsigned    u;                      /* Local index variable */
     char        temp_str[128];          /* Temporary string, for formatting */
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -106,11 +107,20 @@ H5B2_hdr_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     HDassert(indent >= 0);
     HDassert(fwidth >= 0);
     HDassert(type);
+    HDassert((type->crt_dbg_ctx && type->dst_dbg_ctx) ||
+        (NULL == type->crt_dbg_ctx && NULL == type->dst_dbg_ctx));
+
+    /* Check for debugging context callback available */
+    if(type->crt_dbg_ctx) {
+        /* Create debugging context */
+        if(NULL == (dbg_ctx = (type->crt_dbg_ctx)(f, dxpl_id, addr)))
+	    HGOTO_ERROR(H5E_BTREE, H5E_CANTGET, FAIL, "unable to create v2 B-tree debugging context")
+    } /* end if */
 
     /*
      * Load the B-tree header.
      */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, type, NULL, H5AC_READ)))
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, addr, type, dbg_ctx, H5AC_READ)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree header")
 
     /* Set file pointer for this B-tree operation */
@@ -162,6 +172,8 @@ H5B2_hdr_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     } /* end for */
 
 done:
+    if(dbg_ctx && (type->dst_dbg_ctx)(dbg_ctx) < 0)
+        HDONE_ERROR(H5E_BTREE, H5E_CANTRELEASE, FAIL, "unable to release v2 B-tree debugging context")
     if(hdr) {
         hdr->f = NULL;
         if(H5AC_unprotect(f, dxpl_id, H5AC_BT2_HDR, addr, hdr, H5AC__NO_FLAGS_SET) < 0)
@@ -191,6 +203,7 @@ H5B2_int_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
 {
     H5B2_hdr_t	*hdr = NULL;            /* B-tree header */
     H5B2_internal_t	*internal = NULL;   /* B-tree internal node */
+    void        *dbg_ctx = NULL;	/* v2 B-tree debugging context */
     unsigned	u;                      /* Local index variable */
     char        temp_str[128];          /* Temporary string, for formatting */
     herr_t      ret_value=SUCCEED;      /* Return value */
@@ -206,13 +219,22 @@ H5B2_int_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     HDassert(indent >= 0);
     HDassert(fwidth >= 0);
     HDassert(type);
+    HDassert((type->crt_dbg_ctx && type->dst_dbg_ctx) ||
+        (NULL == type->crt_dbg_ctx && NULL == type->dst_dbg_ctx));
     HDassert(H5F_addr_defined(hdr_addr));
     HDassert(nrec > 0);
 
+    /* Check for debugging context callback available */
+    if(type->crt_dbg_ctx) {
+        /* Create debugging context */
+        if(NULL == (dbg_ctx = (type->crt_dbg_ctx)(f, dxpl_id, addr)))
+	    HGOTO_ERROR(H5E_BTREE, H5E_CANTGET, FAIL, "unable to create v2 B-tree debugging context")
+    } /* end if */
+
     /*
      * Load the B-tree header.
      */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, type, NULL, H5AC_READ)))
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, type, dbg_ctx, H5AC_READ)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree header")
 
     /* Set file pointer for this B-tree operation */
@@ -276,6 +298,8 @@ H5B2_int_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
               internal->node_ptrs[u].addr);
 
 done:
+    if(dbg_ctx && (type->dst_dbg_ctx)(dbg_ctx) < 0)
+        HDONE_ERROR(H5E_BTREE, H5E_CANTRELEASE, FAIL, "unable to release v2 B-tree debugging context")
     if(hdr) {
         hdr->f = NULL;
         if(H5AC_unprotect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, hdr, H5AC__NO_FLAGS_SET) < 0)
@@ -307,6 +331,7 @@ H5B2_leaf_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
 {
     H5B2_hdr_t	*hdr = NULL;            /* B-tree header */
     H5B2_leaf_t	*leaf = NULL;           /* B-tree leaf node */
+    void        *dbg_ctx = NULL;	/* v2 B-tree debugging context */
     unsigned	u;                      /* Local index variable */
     char        temp_str[128];          /* Temporary string, for formatting */
     herr_t      ret_value = SUCCEED;    /* Return value */
@@ -322,13 +347,22 @@ H5B2_leaf_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     HDassert(indent >= 0);
     HDassert(fwidth >= 0);
     HDassert(type);
+    HDassert((type->crt_dbg_ctx && type->dst_dbg_ctx) ||
+        (NULL == type->crt_dbg_ctx && NULL == type->dst_dbg_ctx));
     HDassert(H5F_addr_defined(hdr_addr));
     HDassert(nrec > 0);
 
+    /* Check for debugging context callback available */
+    if(type->crt_dbg_ctx) {
+        /* Create debugging context */
+        if(NULL == (dbg_ctx = (type->crt_dbg_ctx)(f, dxpl_id, addr)))
+	    HGOTO_ERROR(H5E_BTREE, H5E_CANTGET, FAIL, "unable to create v2 B-tree debugging context")
+    } /* end if */
+
     /*
      * Load the B-tree header.
      */
-    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, type, NULL, H5AC_READ)))
+    if(NULL == (hdr = (H5B2_hdr_t *)H5AC_protect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, type, dbg_ctx, H5AC_READ)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree header")
 
     /* Set file pointer for this B-tree operation */
@@ -373,6 +407,8 @@ H5B2_leaf_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE *stream, int indent,
     } /* end for */
 
 done:
+    if(dbg_ctx && (type->dst_dbg_ctx)(dbg_ctx) < 0)
+        HDONE_ERROR(H5E_BTREE, H5E_CANTRELEASE, FAIL, "unable to release v2 B-tree debugging context")
     if(hdr) {
         hdr->f = NULL;
         if(H5AC_unprotect(f, dxpl_id, H5AC_BT2_HDR, hdr_addr, hdr, H5AC__NO_FLAGS_SET) < 0)
diff --git a/src/H5B2hdr.c b/src/H5B2hdr.c
index ec46729..f1d5d84 100644
--- a/src/H5B2hdr.c
+++ b/src/H5B2hdr.c
@@ -108,7 +108,7 @@ H5FL_SEQ_DEFINE(H5B2_node_info_t);
  */
 herr_t
 H5B2_hdr_init(H5F_t *f, H5B2_hdr_t *hdr, const H5B2_create_t *cparam,
-    uint16_t depth)
+    void *ctx_udata, uint16_t depth)
 {
     size_t sz_max_nrec;                 /* Temporary variable for range checking */
     unsigned u_max_nrec_size;           /* Temporary variable for range checking */
@@ -124,6 +124,8 @@ H5B2_hdr_init(H5F_t *f, H5B2_hdr_t *hdr, const H5B2_create_t *cparam,
     HDassert(hdr);
     HDassert(cparam);
     HDassert(cparam->cls);
+    HDassert((cparam->cls->crt_context && cparam->cls->dst_context) ||
+        (NULL == cparam->cls->crt_context && NULL == cparam->cls->dst_context));
     HDassert(cparam->node_size > 0);
     HDassert(cparam->rrec_size > 0);
     HDassert(cparam->merge_percent > 0 && cparam->merge_percent <= 100);
@@ -149,14 +151,14 @@ H5B2_hdr_init(H5F_t *f, H5B2_hdr_t *hdr, const H5B2_create_t *cparam,
 
     /* Allocate "page" for node I/O */
     if(NULL == (hdr->page = H5FL_BLK_MALLOC(node_page, hdr->node_size)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+        HGOTO_ERROR(H5E_BTREE, H5E_NOSPACE, FAIL, "memory allocation failed")
 #ifdef H5_CLEAR_MEMORY
 HDmemset(hdr->page, 0, hdr->node_size);
 #endif /* H5_CLEAR_MEMORY */
 
     /* Allocate array of node info structs */
     if(NULL == (hdr->node_info = H5FL_SEQ_MALLOC(H5B2_node_info_t, (size_t)(hdr->depth + 1))))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+        HGOTO_ERROR(H5E_BTREE, H5E_NOSPACE, FAIL, "memory allocation failed")
 
     /* Initialize leaf node info */
     sz_max_nrec = H5B2_NUM_LEAF_REC(hdr->node_size, hdr->rrec_size);
@@ -166,13 +168,13 @@ HDmemset(hdr->page, 0, hdr->node_size);
     hdr->node_info[0].cum_max_nrec = hdr->node_info[0].max_nrec;
     hdr->node_info[0].cum_max_nrec_size = 0;
     if(NULL == (hdr->node_info[0].nat_rec_fac = H5FL_fac_init(hdr->cls->nrec_size * hdr->node_info[0].max_nrec)))
-	HGOTO_ERROR(H5E_RESOURCE, H5E_CANTINIT, FAIL, "can't create node native key block factory")
+	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "can't create node native key block factory")
     hdr->node_info[0].node_ptr_fac = NULL;
 
     /* Allocate array of pointers to internal node native keys */
     /* (uses leaf # of records because its the largest) */
     if(NULL == (hdr->nat_off = H5FL_SEQ_MALLOC(size_t, (size_t)hdr->node_info[0].max_nrec)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+        HGOTO_ERROR(H5E_BTREE, H5E_NOSPACE, FAIL, "memory allocation failed")
 
     /* Initialize offsets in native key block */
     /* (uses leaf # of records because its the largest) */
@@ -201,12 +203,18 @@ HDmemset(hdr->page, 0, hdr->node_size);
             H5_ASSIGN_OVERFLOW(/* To: */ hdr->node_info[u].cum_max_nrec_size, /* From: */ u_max_nrec_size, /* From: */ unsigned, /* To: */ uint8_t)
 
             if(NULL == (hdr->node_info[u].nat_rec_fac = H5FL_fac_init(hdr->cls->nrec_size * hdr->node_info[u].max_nrec)))
-                HGOTO_ERROR(H5E_RESOURCE, H5E_CANTINIT, FAIL, "can't create node native key block factory")
+                HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "can't create node native key block factory")
             if(NULL == (hdr->node_info[u].node_ptr_fac = H5FL_fac_init(sizeof(H5B2_node_ptr_t) * (hdr->node_info[u].max_nrec + 1))))
-                HGOTO_ERROR(H5E_RESOURCE, H5E_CANTINIT, FAIL, "can't create internal 'branch' node node pointer block factory")
+                HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, FAIL, "can't create internal 'branch' node node pointer block factory")
         } /* end for */
     } /* end if */
 
+    /* Create the callback context, if the callback exists */
+    if(hdr->cls->crt_context) {
+        if(NULL == (hdr->cb_ctx = (*hdr->cls->crt_context)(ctx_udata)))
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTCREATE, FAIL, "unable to create v2 B-tree client callback context")
+    } /* end if */
+
 done:
     if(ret_value < 0)
         if(H5B2_hdr_free(hdr) < 0)
@@ -278,7 +286,8 @@ done:
  *-------------------------------------------------------------------------
  */
 haddr_t
-H5B2_hdr_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam)
+H5B2_hdr_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam,
+    void *ctx_udata)
 {
     H5B2_hdr_t *hdr = NULL;     /* The new v2 B-tree header information */
     haddr_t ret_value;          /* Return value */
@@ -296,7 +305,7 @@ H5B2_hdr_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam)
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTALLOC, HADDR_UNDEF, "allocation failed for B-tree header")
 
     /* Initialize shared B-tree info */
-    if(H5B2_hdr_init(f, hdr, cparam, (uint16_t)0) < 0)
+    if(H5B2_hdr_init(f, hdr, cparam, ctx_udata, (uint16_t)0) < 0)
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTINIT, HADDR_UNDEF, "can't create shared B-tree info")
 
     /* Allocate space for the header on disk */
@@ -507,6 +516,13 @@ H5B2_hdr_free(H5B2_hdr_t *hdr)
     /* Sanity check */
     HDassert(hdr);
 
+    /* Destroy the callback context */
+    if(hdr->cb_ctx) {
+        if((*hdr->cls->dst_context)(hdr->cb_ctx) < 0)
+            HGOTO_ERROR(H5E_BTREE, H5E_CANTRELEASE, FAIL, "can't destroy v2 B-tree client callback context")
+        hdr->cb_ctx = NULL;
+    } /* end if */
+
     /* Free the B-tree node buffer */
     if(hdr->page)
         (void)H5FL_BLK_FREE(node_page, hdr->page);
diff --git a/src/H5B2pkg.h b/src/H5B2pkg.h
index 8b68d1e..c336227 100644
--- a/src/H5B2pkg.h
+++ b/src/H5B2pkg.h
@@ -168,10 +168,13 @@ typedef struct H5B2_hdr_t {
     uint8_t     sizeof_addr;    /* Size of file addresses */
     H5B2_remove_t remove_op;    /* Callback operator for deleting B-tree */
     void        *remove_op_data;/* B-tree deletion callback's context */
-    const H5B2_class_t *cls;	/* Class of B-tree client */
     uint8_t	*page;	        /* Common disk page for I/O */
     size_t      *nat_off;       /* Array of offsets of native records */
     H5B2_node_info_t *node_info; /* Table of node info structs for current depth of B-tree */
+
+    /* Client information (not stored) */
+    const H5B2_class_t *cls;	/* Class of B-tree client */
+    void        *cb_ctx;        /* Client callback context */
 } H5B2_hdr_t;
 
 /* B-tree leaf node information */
@@ -255,9 +258,9 @@ extern const H5B2_class_t *const H5B2_client_class_g[];
 /* Routines for managing B-tree header info */
 H5_DLL H5B2_hdr_t *H5B2_hdr_alloc(H5F_t *f);
 H5_DLL haddr_t H5B2_hdr_create(H5F_t *f, hid_t dxpl_id,
-    const H5B2_create_t *cparam);
+    const H5B2_create_t *cparam, void *ctx_udata);
 H5_DLL herr_t H5B2_hdr_init(H5F_t *f, H5B2_hdr_t *hdr,
-    const H5B2_create_t *cparam, uint16_t depth);
+    const H5B2_create_t *cparam, void *ctx_udata, uint16_t depth);
 H5_DLL herr_t H5B2_hdr_incr(H5B2_hdr_t *hdr);
 H5_DLL herr_t H5B2_hdr_decr(H5B2_hdr_t *hdr);
 H5_DLL herr_t H5B2_hdr_fuse_incr(H5B2_hdr_t *hdr);
diff --git a/src/H5B2private.h b/src/H5B2private.h
index cfdf868..4880ab2 100644
--- a/src/H5B2private.h
+++ b/src/H5B2private.h
@@ -85,20 +85,17 @@ struct H5B2_class_t {
     const char *name;		/* Name of B-tree class, for debugging */
     size_t nrec_size;           /* Size of native (memory) record */
 
-    /* Store record from application to B-tree 'native' form */
-    herr_t (*store)(void *nrecord, const void *udata);                  /*  Store record in native record table */
-
-    /* Compare records, according to a key */
-    herr_t (*compare)(const void *rec1, const void *rec2);              /*  Compare two native records */
-
-    /* Encode & decode record values */
-    herr_t (*encode)(const H5F_t *f, uint8_t *raw, const void *record); /*  Encode record from native form to disk storage form */
-    herr_t (*decode)(const H5F_t *f, const uint8_t *raw, void *record); /*  Decode record from disk storage form to native form */
-
-    /* Debug record values */
-    herr_t (*debug)(FILE *stream, const H5F_t *f, hid_t dxpl_id,        /* Print a record for debugging */
-        int indent, int fwidth, const void *record,
-        const void *udata);
+    /* Extensible array client callback methods */
+    void *(*crt_context)(void *udata);          /* Create context for other client callbacks */
+    herr_t (*dst_context)(void *ctx);           /* Destroy client callback context */
+    herr_t (*store)(void *nrecord, const void *udata);              /*  Store application record in native record table */
+    herr_t (*compare)(const void *rec1, const void *rec2);          /*  Compare two native records */
+    herr_t (*encode)(uint8_t *raw, const void *record, void *ctx);  /*  Encode record from native form to disk storage form */
+    herr_t (*decode)(const uint8_t *raw, void *record, void *ctx);  /*  Decode record from disk storage form to native form */
+    herr_t (*debug)(FILE *stream, const H5F_t *f, hid_t dxpl_id,    /* Print a record for debugging */
+        int indent, int fwidth, const void *record, const void *udata);
+    void *(*crt_dbg_ctx)(H5F_t *f, hid_t dxpl_id, haddr_t obj_addr); /* Create debugging context */
+    herr_t (*dst_dbg_ctx)(void *dbg_ctx);       /* Destroy debugging context */
 };
 
 /* v2 B-tree creation parameters */
@@ -128,8 +125,9 @@ typedef struct H5B2_t H5B2_t;
 /***************************************/
 /* Library-private Function Prototypes */
 /***************************************/
-H5_DLL H5B2_t *H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam);
-H5_DLL H5B2_t *H5B2_open(H5F_t *f, hid_t dxpl_id, haddr_t addr);
+H5_DLL H5B2_t *H5B2_create(H5F_t *f, hid_t dxpl_id, const H5B2_create_t *cparam,
+    void *ctx_udata);
+H5_DLL H5B2_t *H5B2_open(H5F_t *f, hid_t dxpl_id, haddr_t addr, void *ctx_udata);
 H5_DLL herr_t H5B2_get_addr(const H5B2_t *bt2, haddr_t *addr/*out*/);
 H5_DLL herr_t H5B2_insert(H5B2_t *bt2, hid_t dxpl_id, void *udata);
 H5_DLL herr_t H5B2_iterate(H5B2_t *bt2, hid_t dxpl_id, H5B2_operator_t op,
@@ -151,7 +149,7 @@ H5_DLL herr_t H5B2_size(H5B2_t *bt2, hid_t dxpl_id,
     hsize_t *btree_size);
 H5_DLL herr_t H5B2_close(H5B2_t *bt2, hid_t dxpl_id);
 H5_DLL herr_t H5B2_delete(H5F_t *f, hid_t dxpl_id, haddr_t addr,
-    H5B2_remove_t op, void *op_data);
+    void *ctx_udata, H5B2_remove_t op, void *op_data);
 
 /* Statistics routines */
 H5_DLL herr_t H5B2_stat_info(H5B2_t *bt2, H5B2_stat_t *info);
diff --git a/src/H5B2test.c b/src/H5B2test.c
index 863c886..72eb793 100644
--- a/src/H5B2test.c
+++ b/src/H5B2test.c
@@ -46,6 +46,11 @@
 /* Local Typedefs */
 /******************/
 
+/* v2 B-tree client callback context */
+typedef struct H5B2_test_ctx_t {
+    uint8_t     sizeof_size;    /* Size of file sizes */
+} H5B2_test_ctx_t;
+
 
 /********************/
 /* Package Typedefs */
@@ -56,14 +61,15 @@
 /* Local Prototypes */
 /********************/
 
+static void *H5B2_test_crt_context(void *udata);
+static herr_t H5B2_test_dst_context(void *ctx);
 static herr_t H5B2_test_store(void *nrecord, const void *udata);
 static herr_t H5B2_test_compare(const void *rec1, const void *rec2);
-static herr_t H5B2_test_encode(const H5F_t *f, uint8_t *raw,
-    const void *nrecord);
-static herr_t H5B2_test_decode(const H5F_t *f, const uint8_t *raw,
-    void *nrecord);
+static herr_t H5B2_test_encode(uint8_t *raw, const void *nrecord, void *ctx);
+static herr_t H5B2_test_decode(const uint8_t *raw, void *nrecord, void *ctx);
 static herr_t H5B2_test_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
+static void *H5B2_test_crt_dbg_context(H5F_t *f, hid_t dxpl_id, haddr_t addr);
 
 
 /*********************/
@@ -74,11 +80,15 @@ const H5B2_class_t H5B2_TEST[1]={{   /* B-tree class information */
     H5B2_TEST_ID,               /* Type of B-tree */
     "H5B2_TEST_ID",             /* Name of B-tree class */
     sizeof(hsize_t),            /* Size of native record */
+    H5B2_test_crt_context,      /* Create client callback context */
+    H5B2_test_dst_context,      /* Destroy client callback context */
     H5B2_test_store,            /* Record storage callback */
     H5B2_test_compare,          /* Record comparison callback */
     H5B2_test_encode,           /* Record encoding callback */
     H5B2_test_decode,           /* Record decoding callback */
-    H5B2_test_debug             /* Record debugging callback */
+    H5B2_test_debug,            /* Record debugging callback */
+    H5B2_test_crt_dbg_context,  /* Create debugging context */
+    H5B2_test_dst_context       /* Destroy debugging context */
 }};
 
 
@@ -92,6 +102,79 @@ const H5B2_class_t H5B2_TEST[1]={{   /* B-tree class information */
 /*******************/
 
 
+/* Declare a free list to manage the H5B2_test_ctx_t struct */
+H5FL_DEFINE_STATIC(H5B2_test_ctx_t);
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5B2_test_crt_context
+ *
+ * Purpose:	Create client callback context
+ *
+ * Return:	Success:	non-NULL
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 26, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5B2_test_crt_context(void *_f)
+{
+    H5F_t *f = (H5F_t *)_f;     /* User data for building callback context */
+    H5B2_test_ctx_t *ctx;       /* Callback context structure */
+    void *ret_value;            /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5B2_test_crt_context)
+
+    /* Sanity check */
+    HDassert(f);
+
+    /* Allocate callback context */
+    if(NULL == (ctx = H5FL_MALLOC(H5B2_test_ctx_t)))
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTALLOC, NULL, "can't allocate callback context")
+
+    /* Determine the size of lengths in the file */
+    ctx->sizeof_size = H5F_SIZEOF_SIZE(f);
+
+    /* Set return value */
+    ret_value = ctx;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5B2_test_crt_context() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5B2_test_dst_context
+ *
+ * Purpose:	Destroy client callback context
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 26, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5B2_test_dst_context(void *_ctx)
+{
+    H5B2_test_ctx_t *ctx = (H5B2_test_ctx_t *)_ctx;       /* Callback context structure */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5B2_test_dst_context)
+
+    /* Sanity check */
+    HDassert(ctx);
+
+    /* Release callback context */
+    ctx = H5FL_FREE(H5B2_test_ctx_t, ctx);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* H5B2_test_dst_context() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5B2_test_store
@@ -99,7 +182,6 @@ const H5B2_class_t H5B2_TEST[1]={{   /* B-tree class information */
  * Purpose:	Store native information into record for B-tree
  *
  * Return:	Success:	non-negative
- *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
@@ -147,7 +229,6 @@ H5B2_test_compare(const void *rec1, const void *rec2)
  * Purpose:	Encode native information into raw form for storing on disk
  *
  * Return:	Success:	non-negative
- *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
@@ -156,11 +237,16 @@ H5B2_test_compare(const void *rec1, const void *rec2)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5B2_test_encode(const H5F_t *f, uint8_t *raw, const void *nrecord)
+H5B2_test_encode(uint8_t *raw, const void *nrecord, void *_ctx)
 {
+    H5B2_test_ctx_t *ctx = (H5B2_test_ctx_t *)_ctx;       /* Callback context structure */
+
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5B2_test_encode)
 
-    H5F_ENCODE_LENGTH(f, raw, *(const hsize_t *)nrecord);
+    /* Sanity check */
+    HDassert(ctx);
+
+    H5F_ENCODE_LENGTH_LEN(raw, *(const hsize_t *)nrecord, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5B2_test_encode() */
@@ -172,7 +258,6 @@ H5B2_test_encode(const H5F_t *f, uint8_t *raw, const void *nrecord)
  * Purpose:	Decode raw disk form of record into native form
  *
  * Return:	Success:	non-negative
- *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
@@ -181,11 +266,16 @@ H5B2_test_encode(const H5F_t *f, uint8_t *raw, const void *nrecord)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5B2_test_decode(const H5F_t *f, const uint8_t *raw, void *nrecord)
+H5B2_test_decode(const uint8_t *raw, void *nrecord, void *_ctx)
 {
+    H5B2_test_ctx_t *ctx = (H5B2_test_ctx_t *)_ctx;       /* Callback context structure */
+
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5B2_test_decode)
 
-    H5F_DECODE_LENGTH(f, raw, *(hsize_t *)nrecord);
+    /* Sanity check */
+    HDassert(ctx);
+
+    H5F_DECODE_LENGTH_LEN(raw, *(hsize_t *)nrecord, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5B2_test_decode() */
@@ -197,7 +287,6 @@ H5B2_test_decode(const H5F_t *f, const uint8_t *raw, void *nrecord)
  * Purpose:	Debug native form of record
  *
  * Return:	Success:	non-negative
- *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
@@ -222,6 +311,46 @@ H5B2_test_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5B2_test_crt_dbg_context
+ *
+ * Purpose:	Create context for debugging callback
+ *
+ * Return:	Success:	non-NULL
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Tuesday, December 1, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5B2_test_crt_dbg_context(H5F_t *f, hid_t UNUSED dxpl_id, haddr_t UNUSED addr)
+{
+    H5B2_test_ctx_t *ctx;       /* Callback context structure */
+    void *ret_value;            /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5B2_test_crt_dbg_context)
+
+    /* Sanity check */
+    HDassert(f);
+    HDassert(H5F_addr_defined(addr));
+
+    /* Allocate callback context */
+    if(NULL == (ctx = H5FL_MALLOC(H5B2_test_ctx_t)))
+        HGOTO_ERROR(H5E_BTREE, H5E_CANTALLOC, NULL, "can't allocate callback context")
+
+    /* Determine the size of addresses & lengths in the file */
+    ctx->sizeof_size = H5F_SIZEOF_SIZE(f);
+
+    /* Set return value */
+    ret_value = ctx;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5B2_test_crt_dbg_context() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5B2_get_root_addr_test
  *
  * Purpose:	Retrieve the root node's address
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 6031746..c55c616 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -300,20 +300,24 @@ typedef struct H5F_blk_aggr_t H5F_blk_aggr_t;
     case 2: UINT16DECODE(p, o); break;					      \
 }
 
-#define H5F_ENCODE_LENGTH(f,p,l) switch(H5F_SIZEOF_SIZE(f)) {		      \
+#define H5F_ENCODE_LENGTH_LEN(p,l,s) switch(s) {		      	      \
     case 4: UINT32ENCODE(p,l); break;					      \
     case 8: UINT64ENCODE(p,l); break;					      \
     case 2: UINT16ENCODE(p,l); break;					      \
     default: HDassert("bad sizeof size" && 0);				      \
 }
 
-#define H5F_DECODE_LENGTH(f,p,l) switch(H5F_SIZEOF_SIZE(f)) {		      \
+#define H5F_ENCODE_LENGTH(f,p,l) H5F_ENCODE_LENGTH_LEN(p,l,H5F_SIZEOF_SIZE(f))
+
+#define H5F_DECODE_LENGTH_LEN(p,l,s) switch(s) {		              \
     case 4: UINT32DECODE(p,l); break;					      \
     case 8: UINT64DECODE(p,l); break;					      \
     case 2: UINT16DECODE(p,l); break;					      \
     default: HDassert("bad sizeof size" && 0);				      \
 }
 
+#define H5F_DECODE_LENGTH(f,p,l) H5F_DECODE_LENGTH_LEN(p,l,H5F_SIZEOF_SIZE(f))
+
 /*
  * Macros that check for overflows.  These are somewhat dangerous to fiddle
  * with.
diff --git a/src/H5Gbtree2.c b/src/H5Gbtree2.c
index 29ab309..5ae9db1 100644
--- a/src/H5Gbtree2.c
+++ b/src/H5Gbtree2.c
@@ -79,20 +79,20 @@ typedef struct H5G_fh_ud_cmp_t {
 /* v2 B-tree driver callbacks for 'creation order' index */
 static herr_t H5G_dense_btree2_corder_store(void *native, const void *udata);
 static herr_t H5G_dense_btree2_corder_compare(const void *rec1, const void *rec2);
-static herr_t H5G_dense_btree2_corder_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5G_dense_btree2_corder_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
+static herr_t H5G_dense_btree2_corder_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5G_dense_btree2_corder_decode(const uint8_t *raw, void *native,
+    void *ctx);
 static herr_t H5G_dense_btree2_corder_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
 /* v2 B-tree driver callbacks for 'name' index */
 static herr_t H5G_dense_btree2_name_store(void *native, const void *udata);
 static herr_t H5G_dense_btree2_name_compare(const void *rec1, const void *rec2);
-static herr_t H5G_dense_btree2_name_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5G_dense_btree2_name_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
+static herr_t H5G_dense_btree2_name_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5G_dense_btree2_name_decode(const uint8_t *raw, void *native,
+    void *ctx);
 static herr_t H5G_dense_btree2_name_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
@@ -108,11 +108,15 @@ const H5B2_class_t H5G_BT2_NAME[1]={{   /* B-tree class information */
     H5B2_GRP_DENSE_NAME_ID,             /* Type of B-tree */
     "H5B2_GRP_DENSE_NAME_ID",           /* Name of B-tree class */
     sizeof(H5G_dense_bt2_name_rec_t),   /* Size of native record */
+    NULL,                               /* Create client callback context */
+    NULL,                               /* Destroy client callback context */
     H5G_dense_btree2_name_store,        /* Record storage callback */
     H5G_dense_btree2_name_compare,      /* Record comparison callback */
     H5G_dense_btree2_name_encode,       /* Record encoding callback */
     H5G_dense_btree2_name_decode,       /* Record decoding callback */
-    H5G_dense_btree2_name_debug         /* Record debugging callback */
+    H5G_dense_btree2_name_debug,        /* Record debugging callback */
+    NULL,                               /* Create debugging context */
+    NULL                                /* Destroy debugging context */
 }};
 
 /* v2 B-tree class for indexing 'creation order' field of links */
@@ -120,11 +124,15 @@ const H5B2_class_t H5G_BT2_CORDER[1]={{ /* B-tree class information */
     H5B2_GRP_DENSE_CORDER_ID,           /* Type of B-tree */
     "H5B2_GRP_DENSE_CORDER_ID",         /* Name of B-tree class */
     sizeof(H5G_dense_bt2_corder_rec_t), /* Size of native record */
+    NULL,                               /* Create client callback context */
+    NULL,                               /* Destroy client callback context */
     H5G_dense_btree2_corder_store,      /* Record storage callback */
     H5G_dense_btree2_corder_compare,    /* Record comparison callback */
     H5G_dense_btree2_corder_encode,     /* Record encoding callback */
     H5G_dense_btree2_corder_decode,     /* Record decoding callback */
-    H5G_dense_btree2_corder_debug       /* Record debugging callback */
+    H5G_dense_btree2_corder_debug,      /* Record debugging callback */
+    NULL,                               /* Create debugging context */
+    NULL                                /* Destroy debugging context */
 }};
 
 /*****************************/
@@ -298,7 +306,7 @@ for(u = 0; u < H5G_DENSE_FHEAP_ID_LEN; u++)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_btree2_name_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_nrecord)
+H5G_dense_btree2_name_encode(uint8_t *raw, const void *_nrecord, void UNUSED *ctx)
 {
     const H5G_dense_bt2_name_rec_t *nrecord = (const H5G_dense_bt2_name_rec_t *)_nrecord;
 
@@ -326,7 +334,7 @@ H5G_dense_btree2_name_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_n
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_btree2_name_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_nrecord)
+H5G_dense_btree2_name_decode(const uint8_t *raw, void *_nrecord, void UNUSED *ctx)
 {
     H5G_dense_bt2_name_rec_t *nrecord = (H5G_dense_bt2_name_rec_t *)_nrecord;
 
@@ -464,7 +472,7 @@ for(u = 0; u < H5G_DENSE_FHEAP_ID_LEN; u++)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_btree2_corder_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_nrecord)
+H5G_dense_btree2_corder_encode(uint8_t *raw, const void *_nrecord, void UNUSED *ctx)
 {
     const H5G_dense_bt2_corder_rec_t *nrecord = (const H5G_dense_bt2_corder_rec_t *)_nrecord;
 
@@ -492,7 +500,7 @@ H5G_dense_btree2_corder_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5G_dense_btree2_corder_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_nrecord)
+H5G_dense_btree2_corder_decode(const uint8_t *raw, void *_nrecord, void UNUSED *ctx)
 {
     H5G_dense_bt2_corder_rec_t *nrecord = (H5G_dense_bt2_corder_rec_t *)_nrecord;
 
diff --git a/src/H5Gdense.c b/src/H5Gdense.c
index f935a74..9a8e764 100644
--- a/src/H5Gdense.c
+++ b/src/H5Gdense.c
@@ -326,7 +326,7 @@ HDfprintf(stderr, "%s: fheap_id_len = %Zu\n", FUNC, fheap_id_len);
             fheap_id_len;               /* Fractal heap ID */
     bt2_cparam.split_percent = H5G_NAME_BT2_SPLIT_PERC;
     bt2_cparam.merge_percent = H5G_NAME_BT2_MERGE_PERC;
-    if(NULL == (bt2_name = H5B2_create(f, dxpl_id, &bt2_cparam)))
+    if(NULL == (bt2_name = H5B2_create(f, dxpl_id, &bt2_cparam, NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create v2 B-tree for name index")
 
     /* Retrieve the v2 B-tree's address in the file */
@@ -346,7 +346,7 @@ HDfprintf(stderr, "%s: linfo->name_bt2_addr = %a\n", FUNC, linfo->name_bt2_addr)
                 fheap_id_len;           /* Fractal heap ID */
         bt2_cparam.split_percent = H5G_CORDER_BT2_SPLIT_PERC;
         bt2_cparam.merge_percent = H5G_CORDER_BT2_MERGE_PERC;
-        if(NULL == (bt2_corder = H5B2_create(f, dxpl_id, &bt2_cparam)))
+        if(NULL == (bt2_corder = H5B2_create(f, dxpl_id, &bt2_cparam, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create v2 B-tree for creation order index")
 
         /* Retrieve the v2 B-tree's address in the file */
@@ -438,7 +438,7 @@ HDfprintf(stderr, "%s: HDstrlen(lnk->name) = %Zu, link_size = %Zu\n", FUNC, HDst
         HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "unable to insert link into fractal heap")
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, linfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, linfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Create the callback information for v2 B-tree record insertion */
@@ -460,7 +460,7 @@ HDfprintf(stderr, "%s: HDstrlen(lnk->name) = %Zu, link_size = %Zu\n", FUNC, HDst
     if(linfo->index_corder) {
         /* Open the creation order index v2 B-tree */
         HDassert(H5F_addr_defined(linfo->corder_bt2_addr));
-        if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, linfo->corder_bt2_addr)))
+        if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, linfo->corder_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
         /* Insert the record into the creation order index v2 B-tree */
@@ -557,7 +557,7 @@ H5G_dense_lookup(H5F_t *f, hid_t dxpl_id, const H5O_linfo_t *linfo,
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, linfo->name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(f, dxpl_id, linfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Construct the user data for v2 B-tree callback */
@@ -733,7 +733,7 @@ H5G_dense_lookup_by_idx(H5F_t *f, hid_t dxpl_id, const H5O_linfo_t *linfo,
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Construct the user data for v2 B-tree callback */
@@ -1042,7 +1042,7 @@ H5G_dense_iterate(H5F_t *f, hid_t dxpl_id, const H5O_linfo_t *linfo,
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Construct the user data for v2 B-tree iterator callback */
@@ -1244,7 +1244,7 @@ H5G_dense_get_name_by_idx(H5F_t *f, hid_t dxpl_id, H5O_linfo_t *linfo,
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Set up the user data for the v2 B-tree 'record remove' callback */
@@ -1326,7 +1326,7 @@ H5G_dense_remove_fh_cb(const void *obj, size_t UNUSED obj_len, void *_udata)
         H5G_bt2_ud_common_t bt2_udata;         /* Info for B-tree callbacks */
 
         /* Open the creation order index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(udata->f, udata->dxpl_id, udata->corder_bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(udata->f, udata->dxpl_id, udata->corder_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
         /* Set up the user data for the v2 B-tree 'record remove' callback */
@@ -1440,7 +1440,7 @@ H5G_dense_remove(H5F_t *f, hid_t dxpl_id, const H5O_linfo_t *linfo,
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2 = H5B2_open(f, dxpl_id, linfo->name_bt2_addr)))
+    if(NULL == (bt2 = H5B2_open(f, dxpl_id, linfo->name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Set up the user data for the v2 B-tree 'record remove' callback */
@@ -1577,7 +1577,7 @@ H5G_dense_remove_by_idx_bt2_cb(const void *_record, void *_bt2_udata)
         } /* end else */
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(bt2_udata->f, bt2_udata->dxpl_id, bt2_udata->other_bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(bt2_udata->f, bt2_udata->dxpl_id, bt2_udata->other_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for 'other' index")
 
         /* Set the common information for the v2 B-tree remove operation */
@@ -1682,7 +1682,7 @@ H5G_dense_remove_by_idx(H5F_t *f, hid_t dxpl_id, const H5O_linfo_t *linfo,
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open fractal heap")
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for index")
 
         /* Set up the user data for the v2 B-tree 'remove by index' callback */
@@ -1776,7 +1776,7 @@ H5G_dense_delete(H5F_t *f, hid_t dxpl_id, H5O_linfo_t *linfo, hbool_t adj_link)
         udata.replace_names = FALSE;
 
         /* Delete the name index, adjusting the ref. count on links removed */
-        if(H5B2_delete(f, dxpl_id, linfo->name_bt2_addr, H5G_dense_remove_bt2_cb, &udata) < 0)
+        if(H5B2_delete(f, dxpl_id, linfo->name_bt2_addr, NULL, H5G_dense_remove_bt2_cb, &udata) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree for name index")
 
         /* Close the fractal heap */
@@ -1785,7 +1785,7 @@ H5G_dense_delete(H5F_t *f, hid_t dxpl_id, H5O_linfo_t *linfo, hbool_t adj_link)
     } /* end if */
     else {
         /* Delete the name index, without adjusting the ref. count on the links  */
-        if(H5B2_delete(f, dxpl_id, linfo->name_bt2_addr, NULL, NULL) < 0)
+        if(H5B2_delete(f, dxpl_id, linfo->name_bt2_addr, NULL, NULL, NULL) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree for name index")
     } /* end else */
     linfo->name_bt2_addr = HADDR_UNDEF;
@@ -1794,7 +1794,7 @@ H5G_dense_delete(H5F_t *f, hid_t dxpl_id, H5O_linfo_t *linfo, hbool_t adj_link)
     if(linfo->index_corder) {
         /* Delete the creation order index, without adjusting the ref. count on the links  */
         HDassert(H5F_addr_defined(linfo->corder_bt2_addr));
-        if(H5B2_delete(f, dxpl_id, linfo->corder_bt2_addr, NULL, NULL) < 0)
+        if(H5B2_delete(f, dxpl_id, linfo->corder_bt2_addr, NULL, NULL, NULL) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete v2 B-tree for creation order index")
         linfo->corder_bt2_addr = HADDR_UNDEF;
     } /* end if */
diff --git a/src/H5Gobj.c b/src/H5Gobj.c
index 4281ac0..271501f 100644
--- a/src/H5Gobj.c
+++ b/src/H5Gobj.c
@@ -331,7 +331,7 @@ H5G_obj_get_linfo(const H5O_loc_t *grp_oloc, H5O_linfo_t *linfo, hid_t dxpl_id)
             /* Check if we are using "dense" link storage */
             if(H5F_addr_defined(linfo->fheap_addr)) {
                 /* Open the name index v2 B-tree */
-                if(NULL == (bt2_name = H5B2_open(grp_oloc->file, dxpl_id, linfo->name_bt2_addr)))
+                if(NULL == (bt2_name = H5B2_open(grp_oloc->file, dxpl_id, linfo->name_bt2_addr, NULL)))
                     HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
                 /* Retrieve # of records in "name" B-tree */
diff --git a/src/H5Goh.c b/src/H5Goh.c
index 2494838..ea51179 100644
--- a/src/H5Goh.c
+++ b/src/H5Goh.c
@@ -360,7 +360,7 @@ H5O_group_bh_info(H5F_t *f, hid_t dxpl_id, H5O_t *oh, H5_ih_info_t *bh_info)
         /* Check if name index available */
         if(H5F_addr_defined(linfo.name_bt2_addr)) {
             /* Open the name index v2 B-tree */
-            if(NULL == (bt2_name = H5B2_open(f, dxpl_id, linfo.name_bt2_addr)))
+            if(NULL == (bt2_name = H5B2_open(f, dxpl_id, linfo.name_bt2_addr, NULL)))
                 HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
             /* Get name index B-tree size */
@@ -371,7 +371,7 @@ H5O_group_bh_info(H5F_t *f, hid_t dxpl_id, H5O_t *oh, H5_ih_info_t *bh_info)
         /* Check if creation order index available */
 	if(H5F_addr_defined(linfo.corder_bt2_addr)) {
             /* Open the creation order index v2 B-tree */
-            if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, linfo.corder_bt2_addr)))
+            if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, linfo.corder_bt2_addr, NULL)))
                 HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
             /* Get creation order index B-tree size */
diff --git a/src/H5Gtest.c b/src/H5Gtest.c
index 791c13a..26de267 100644
--- a/src/H5Gtest.c
+++ b/src/H5Gtest.c
@@ -405,7 +405,7 @@ H5G_new_dense_info_test(hid_t gid, hsize_t *name_count, hsize_t *corder_count)
         HGOTO_DONE(FAIL)
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(grp->oloc.file, H5AC_dxpl_id, linfo.name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(grp->oloc.file, H5AC_dxpl_id, linfo.name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Retrieve # of records in name index */
@@ -415,7 +415,7 @@ H5G_new_dense_info_test(hid_t gid, hsize_t *name_count, hsize_t *corder_count)
     /* Check if there is a creation order index */
     if(H5F_addr_defined(linfo.corder_bt2_addr)) {
         /* Open the creation order index v2 B-tree */
-        if(NULL == (bt2_corder = H5B2_open(grp->oloc.file, H5AC_dxpl_id, linfo.corder_bt2_addr)))
+        if(NULL == (bt2_corder = H5B2_open(grp->oloc.file, H5AC_dxpl_id, linfo.corder_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
         /* Retrieve # of records in creation order index */
diff --git a/src/H5HFbtree2.c b/src/H5HFbtree2.c
index ae50bf3..3f208e7 100644
--- a/src/H5HFbtree2.c
+++ b/src/H5HFbtree2.c
@@ -49,6 +49,12 @@
 /* Local Typedefs */
 /******************/
 
+/* v2 B-tree client callback context */
+typedef struct H5HF_huge_bt2_ctx_t {
+    uint8_t     sizeof_size;    /* Size of file sizes */
+    uint8_t     sizeof_addr;    /* Size of file addresses */
+} H5HF_huge_bt2_ctx_t;
+
 
 /********************/
 /* Package Typedefs */
@@ -59,92 +65,114 @@
 /* Local Prototypes */
 /********************/
 
+
 /* v2 B-tree driver callbacks */
-static herr_t H5HF_huge_btree2_indir_store(void *native, const void *udata);
-static herr_t H5HF_huge_btree2_indir_compare(const void *rec1, const void *rec2);
-static herr_t H5HF_huge_btree2_indir_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5HF_huge_btree2_indir_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
-static herr_t H5HF_huge_btree2_indir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
+
+static void *H5HF_huge_bt2_crt_context(void *udata);
+static herr_t H5HF_huge_bt2_dst_context(void *ctx);
+static void *H5HF_huge_bt2_crt_dbg_context(H5F_t *f, hid_t dxpl_id, haddr_t addr);
+
+static herr_t H5HF_huge_bt2_indir_store(void *native, const void *udata);
+static herr_t H5HF_huge_bt2_indir_compare(const void *rec1, const void *rec2);
+static herr_t H5HF_huge_bt2_indir_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_indir_decode(const uint8_t *raw, void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_indir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
-static herr_t H5HF_huge_btree2_filt_indir_store(void *native, const void *udata);
-static herr_t H5HF_huge_btree2_filt_indir_compare(const void *rec1, const void *rec2);
-static herr_t H5HF_huge_btree2_filt_indir_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5HF_huge_btree2_filt_indir_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
-static herr_t H5HF_huge_btree2_filt_indir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
+static herr_t H5HF_huge_bt2_filt_indir_store(void *native, const void *udata);
+static herr_t H5HF_huge_bt2_filt_indir_compare(const void *rec1, const void *rec2);
+static herr_t H5HF_huge_bt2_filt_indir_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_filt_indir_decode(const uint8_t *raw, void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_filt_indir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
-static herr_t H5HF_huge_btree2_dir_store(void *native, const void *udata);
-static herr_t H5HF_huge_btree2_dir_compare(const void *rec1, const void *rec2);
-static herr_t H5HF_huge_btree2_dir_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5HF_huge_btree2_dir_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
-static herr_t H5HF_huge_btree2_dir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
+static herr_t H5HF_huge_bt2_dir_store(void *native, const void *udata);
+static herr_t H5HF_huge_bt2_dir_compare(const void *rec1, const void *rec2);
+static herr_t H5HF_huge_bt2_dir_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_dir_decode(const uint8_t *raw, void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_dir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
-static herr_t H5HF_huge_btree2_filt_dir_store(void *native, const void *udata);
-static herr_t H5HF_huge_btree2_filt_dir_compare(const void *rec1, const void *rec2);
-static herr_t H5HF_huge_btree2_filt_dir_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-static herr_t H5HF_huge_btree2_filt_dir_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
-static herr_t H5HF_huge_btree2_filt_dir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
+static herr_t H5HF_huge_bt2_filt_dir_store(void *native, const void *udata);
+static herr_t H5HF_huge_bt2_filt_dir_compare(const void *rec1, const void *rec2);
+static herr_t H5HF_huge_bt2_filt_dir_encode(uint8_t *raw, const void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_filt_dir_decode(const uint8_t *raw, void *native,
+    void *ctx);
+static herr_t H5HF_huge_bt2_filt_dir_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
 
 /*********************/
 /* Package Variables */
 /*********************/
 /* v2 B-tree class for indirectly accessed 'huge' objects */
-const H5B2_class_t H5HF_BT2_INDIR[1]={{     /* B-tree class information */
-    H5B2_FHEAP_HUGE_INDIR_ID,           /* Type of B-tree */
-    "H5B2_FHEAP_HUGE_INDIR_ID",         /* Name of B-tree class */
-    sizeof(H5HF_huge_bt2_indir_rec_t),  /* Size of native record */
-    H5HF_huge_btree2_indir_store,       /* Record storage callback */
-    H5HF_huge_btree2_indir_compare,     /* Record comparison callback */
-    H5HF_huge_btree2_indir_encode,      /* Record encoding callback */
-    H5HF_huge_btree2_indir_decode,      /* Record decoding callback */
-    H5HF_huge_btree2_indir_debug        /* Record debugging callback */
+const H5B2_class_t H5HF_HUGE_BT2_INDIR[1]={{ /* B-tree class information */
+    H5B2_FHEAP_HUGE_INDIR_ID,               /* Type of B-tree */
+    "H5B2_FHEAP_HUGE_INDIR_ID",             /* Name of B-tree class */
+    sizeof(H5HF_huge_bt2_indir_rec_t),      /* Size of native record */
+    H5HF_huge_bt2_crt_context,              /* Create client callback context */
+    H5HF_huge_bt2_dst_context,              /* Destroy client callback context */
+    H5HF_huge_bt2_indir_store,              /* Record storage callback */
+    H5HF_huge_bt2_indir_compare,            /* Record comparison callback */
+    H5HF_huge_bt2_indir_encode,             /* Record encoding callback */
+    H5HF_huge_bt2_indir_decode,             /* Record decoding callback */
+    H5HF_huge_bt2_indir_debug,              /* Record debugging callback */
+    H5HF_huge_bt2_crt_dbg_context,          /* Create debugging context */
+    H5HF_huge_bt2_dst_context               /* Destroy debugging context */
 }};
 
 /* v2 B-tree class for indirectly accessed, filtered 'huge' objects */
-const H5B2_class_t H5HF_BT2_FILT_INDIR[1]={{    /* B-tree class information */
-    H5B2_FHEAP_HUGE_FILT_INDIR_ID,              /* Type of B-tree */
-    "H5B2_FHEAP_HUGE_FILT_INDIR_ID",            /* Name of B-tree class */
-    sizeof(H5HF_huge_bt2_filt_indir_rec_t),     /* Size of native record */
-    H5HF_huge_btree2_filt_indir_store,          /* Record storage callback */
-    H5HF_huge_btree2_filt_indir_compare,        /* Record comparison callback */
-    H5HF_huge_btree2_filt_indir_encode,         /* Record encoding callback */
-    H5HF_huge_btree2_filt_indir_decode,         /* Record decoding callback */
-    H5HF_huge_btree2_filt_indir_debug           /* Record debugging callback */
+const H5B2_class_t H5HF_HUGE_BT2_FILT_INDIR[1]={{ /* B-tree class information */
+    H5B2_FHEAP_HUGE_FILT_INDIR_ID,          /* Type of B-tree */
+    "H5B2_FHEAP_HUGE_FILT_INDIR_ID",        /* Name of B-tree class */
+    sizeof(H5HF_huge_bt2_filt_indir_rec_t), /* Size of native record */
+    H5HF_huge_bt2_crt_context,              /* Create client callback context */
+    H5HF_huge_bt2_dst_context,              /* Destroy client callback context */
+    H5HF_huge_bt2_filt_indir_store,         /* Record storage callback */
+    H5HF_huge_bt2_filt_indir_compare,       /* Record comparison callback */
+    H5HF_huge_bt2_filt_indir_encode,        /* Record encoding callback */
+    H5HF_huge_bt2_filt_indir_decode,        /* Record decoding callback */
+    H5HF_huge_bt2_filt_indir_debug,         /* Record debugging callback */
+    H5HF_huge_bt2_crt_dbg_context,          /* Create debugging context */
+    H5HF_huge_bt2_dst_context               /* Destroy debugging context */
 }};
 
 /* v2 B-tree class for directly accessed 'huge' objects */
-const H5B2_class_t H5HF_BT2_DIR[1]={{   /* B-tree class information */
-    H5B2_FHEAP_HUGE_DIR_ID,             /* Type of B-tree */
-    "H5B2_FHEAP_HUGE_DIR_ID",           /* Name of B-tree class */
-    sizeof(H5HF_huge_bt2_dir_rec_t),    /* Size of native record */
-    H5HF_huge_btree2_dir_store,         /* Record storage callback */
-    H5HF_huge_btree2_dir_compare,       /* Record comparison callback */
-    H5HF_huge_btree2_dir_encode,        /* Record encoding callback */
-    H5HF_huge_btree2_dir_decode,        /* Record decoding callback */
-    H5HF_huge_btree2_dir_debug          /* Record debugging callback */
+const H5B2_class_t H5HF_HUGE_BT2_DIR[1]={{  /* B-tree class information */
+    H5B2_FHEAP_HUGE_DIR_ID,                 /* Type of B-tree */
+    "H5B2_FHEAP_HUGE_DIR_ID",               /* Name of B-tree class */
+    sizeof(H5HF_huge_bt2_dir_rec_t),        /* Size of native record */
+    H5HF_huge_bt2_crt_context,              /* Create client callback context */
+    H5HF_huge_bt2_dst_context,              /* Destroy client callback context */
+    H5HF_huge_bt2_dir_store,                /* Record storage callback */
+    H5HF_huge_bt2_dir_compare,              /* Record comparison callback */
+    H5HF_huge_bt2_dir_encode,               /* Record encoding callback */
+    H5HF_huge_bt2_dir_decode,               /* Record decoding callback */
+    H5HF_huge_bt2_dir_debug,                /* Record debugging callback */
+    H5HF_huge_bt2_crt_dbg_context,          /* Create debugging context */
+    H5HF_huge_bt2_dst_context               /* Destroy debugging context */
 }};
 
 /* v2 B-tree class for directly accessed, filtered 'huge' objects */
-const H5B2_class_t H5HF_BT2_FILT_DIR[1]={{ /* B-tree class information */
-    H5B2_FHEAP_HUGE_FILT_DIR_ID,        /* Type of B-tree */
-    "H5B2_FHEAP_HUGE_FILT_DIR_ID",      /* Name of B-tree class */
-    sizeof(H5HF_huge_bt2_filt_dir_rec_t),/* Size of native record */
-    H5HF_huge_btree2_filt_dir_store,    /* Record storage callback */
-    H5HF_huge_btree2_filt_dir_compare,  /* Record comparison callback */
-    H5HF_huge_btree2_filt_dir_encode,   /* Record encoding callback */
-    H5HF_huge_btree2_filt_dir_decode,   /* Record decoding callback */
-    H5HF_huge_btree2_filt_dir_debug     /* Record debugging callback */
+const H5B2_class_t H5HF_HUGE_BT2_FILT_DIR[1]={{ /* B-tree class information */
+    H5B2_FHEAP_HUGE_FILT_DIR_ID,            /* Type of B-tree */
+    "H5B2_FHEAP_HUGE_FILT_DIR_ID",          /* Name of B-tree class */
+    sizeof(H5HF_huge_bt2_filt_dir_rec_t),   /* Size of native record */
+    H5HF_huge_bt2_crt_context,              /* Create client callback context */
+    H5HF_huge_bt2_dst_context,              /* Destroy client callback context */
+    H5HF_huge_bt2_filt_dir_store,           /* Record storage callback */
+    H5HF_huge_bt2_filt_dir_compare,         /* Record comparison callback */
+    H5HF_huge_bt2_filt_dir_encode,          /* Record encoding callback */
+    H5HF_huge_bt2_filt_dir_decode,          /* Record decoding callback */
+    H5HF_huge_bt2_filt_dir_debug,           /* Record debugging callback */
+    H5HF_huge_bt2_crt_dbg_context,          /* Create debugging context */
+    H5HF_huge_bt2_dst_context               /* Destroy debugging context */
 }};
 
 /*****************************/
@@ -156,6 +184,126 @@ const H5B2_class_t H5HF_BT2_FILT_DIR[1]={{ /* B-tree class information */
 /* Local Variables */
 /*******************/
 
+/* Declare a free list to manage the H5HF_huge_bt2_ctx_t struct */
+H5FL_DEFINE_STATIC(H5HF_huge_bt2_ctx_t);
+
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF_huge_bt2_crt_context
+ *
+ * Purpose:	Create client callback context
+ *
+ * Note:	Common to all 'huge' v2 B-tree clients
+ *
+ * Return:	Success:	non-NULL
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 26, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5HF_huge_bt2_crt_context(void *_f)
+{
+    H5F_t *f = (H5F_t *)_f;     /* User data for building callback context */
+    H5HF_huge_bt2_ctx_t *ctx;   /* Callback context structure */
+    void *ret_value;            /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_huge_bt2_crt_context)
+
+    /* Sanity check */
+    HDassert(f);
+
+    /* Allocate callback context */
+    if(NULL == (ctx = H5FL_MALLOC(H5HF_huge_bt2_ctx_t)))
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate callback context")
+
+    /* Determine the size of addresses & lengths in the file */
+    ctx->sizeof_addr = H5F_SIZEOF_ADDR(f);
+    ctx->sizeof_size = H5F_SIZEOF_SIZE(f);
+
+    /* Set return value */
+    ret_value = ctx;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5HF_huge_bt2_crt_context() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF_huge_bt2_dst_context
+ *
+ * Purpose:	Destroy client callback context
+ *
+ * Note:	Common to all 'huge' v2 B-tree clients
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 26, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5HF_huge_bt2_dst_context(void *_ctx)
+{
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_dst_context)
+
+    /* Sanity check */
+    HDassert(ctx);
+
+    /* Release callback context */
+    ctx = H5FL_FREE(H5HF_huge_bt2_ctx_t, ctx);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* H5HF_huge_bt2_dst_context() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5HF_huge_bt2_crt_dbg_context
+ *
+ * Purpose:	Create context for debugging callback
+ *
+ * Return:	Success:	non-NULL
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Tuesday, December 1, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5HF_huge_bt2_crt_dbg_context(H5F_t *f, hid_t UNUSED dxpl_id, haddr_t UNUSED addr)
+{
+    H5HF_huge_bt2_ctx_t *ctx;   /* Callback context structure */
+    void *ret_value;            /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5HF_huge_bt2_crt_dbg_context)
+
+    /* Sanity check */
+    HDassert(f);
+    HDassert(H5F_addr_defined(addr));
+
+    /* Allocate callback context */
+    if(NULL == (ctx = H5FL_MALLOC(H5HF_huge_bt2_ctx_t)))
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate callback context")
+
+    /* Determine the size of addresses & lengths in the file */
+    ctx->sizeof_addr = H5F_SIZEOF_ADDR(f);
+    ctx->sizeof_size = H5F_SIZEOF_SIZE(f);
+
+    /* Set return value */
+    ret_value = ctx;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5HF_huge_bt2_crt_dbg_context() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5HF_huge_bt2_indir_found
@@ -223,7 +371,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_indir_store
+ * Function:	H5HF_huge_bt2_indir_store
  *
  * Purpose:	Store native information into record for v2 B-tree
  *
@@ -236,18 +384,18 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_indir_store(void *nrecord, const void *udata)
+H5HF_huge_bt2_indir_store(void *nrecord, const void *udata)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_indir_store)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_indir_store)
 
     *(H5HF_huge_bt2_indir_rec_t *)nrecord = *(const H5HF_huge_bt2_indir_rec_t *)udata;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_indir_store() */
+} /* H5HF_huge_bt2_indir_store() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_indir_compare
+ * Function:	H5HF_huge_bt2_indir_compare
  *
  * Purpose:	Compare two native information records, according to some key
  *
@@ -261,25 +409,25 @@ H5HF_huge_btree2_indir_store(void *nrecord, const void *udata)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_indir_compare(const void *_rec1, const void *_rec2)
+H5HF_huge_bt2_indir_compare(const void *_rec1, const void *_rec2)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_indir_compare)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_indir_compare)
 
 #ifdef QAK
 {
 const H5HF_huge_bt2_indir_rec_t *rec1 = (const H5HF_huge_bt2_indir_rec_t *)_rec1;
 const H5HF_huge_bt2_indir_rec_t *rec2 = (const H5HF_huge_bt2_indir_rec_t *)_rec2;
 
-HDfprintf(stderr, "%s: rec1 = {%a, %Hu, %Hu}\n", "H5HF_huge_btree2_indir_compare", rec1->addr, rec1->len, rec1->id);
-HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %Hu}\n", "H5HF_huge_btree2_indir_compare", rec2->addr, rec2->len, rec2->id);
+HDfprintf(stderr, "%s: rec1 = {%a, %Hu, %Hu}\n", "H5HF_huge_bt2_indir_compare", rec1->addr, rec1->len, rec1->id);
+HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %Hu}\n", "H5HF_huge_bt2_indir_compare", rec2->addr, rec2->len, rec2->id);
 }
 #endif /* QAK */
     FUNC_LEAVE_NOAPI((herr_t)(((const H5HF_huge_bt2_indir_rec_t *)_rec1)->id - ((const H5HF_huge_bt2_indir_rec_t *)_rec2)->id))
-} /* H5HF_huge_btree2_indir_compare() */
+} /* H5HF_huge_bt2_indir_compare() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_indir_encode
+ * Function:	H5HF_huge_bt2_indir_encode
  *
  * Purpose:	Encode native information into raw form for storing on disk
  *
@@ -292,23 +440,27 @@ HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %Hu}\n", "H5HF_huge_btree2_indir_compare
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_indir_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord)
+H5HF_huge_bt2_indir_encode(uint8_t *raw, const void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     const H5HF_huge_bt2_indir_rec_t *nrecord = (const H5HF_huge_bt2_indir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_indir_encode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_indir_encode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Encode the record's fields */
-    H5F_addr_encode(f, &raw, nrecord->addr);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->len);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->id);
+    H5F_addr_encode_len(ctx->sizeof_addr, &raw, nrecord->addr);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->id, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_indir_encode() */
+} /* H5HF_huge_bt2_indir_encode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_indir_decode
+ * Function:	H5HF_huge_bt2_indir_decode
  *
  * Purpose:	Decode raw disk form of record into native form
  *
@@ -321,23 +473,27 @@ H5HF_huge_btree2_indir_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_indir_decode(const H5F_t *f, const uint8_t *raw, void *_nrecord)
+H5HF_huge_bt2_indir_decode(const uint8_t *raw, void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     H5HF_huge_bt2_indir_rec_t *nrecord = (H5HF_huge_bt2_indir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_indir_decode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_indir_decode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Decode the record's fields */
-    H5F_addr_decode(f, &raw, &nrecord->addr);
-    H5F_DECODE_LENGTH(f, raw, nrecord->len);
-    H5F_DECODE_LENGTH(f, raw, nrecord->id);
+    H5F_addr_decode_len(ctx->sizeof_addr, &raw, &nrecord->addr);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->id, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_indir_decode() */
+} /* H5HF_huge_bt2_indir_decode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_indir_debug
+ * Function:	H5HF_huge_bt2_indir_debug
  *
  * Purpose:	Debug native form of record
  *
@@ -350,19 +506,19 @@ H5HF_huge_btree2_indir_decode(const H5F_t *f, const uint8_t *raw, void *_nrecord
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_indir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
+H5HF_huge_bt2_indir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
     int indent, int fwidth, const void *_nrecord,
     const void UNUSED *_udata)
 {
     const H5HF_huge_bt2_indir_rec_t *nrecord = (const H5HF_huge_bt2_indir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_indir_debug)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_indir_debug)
 
     HDfprintf(stream, "%*s%-*s {%a, %Hu, %Hu}\n", indent, "", fwidth, "Record:",
         nrecord->addr, nrecord->len, nrecord->id);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_indir_debug() */
+} /* H5HF_huge_bt2_indir_debug() */
 
 
 /*-------------------------------------------------------------------------
@@ -433,7 +589,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_indir_store
+ * Function:	H5HF_huge_bt2_filt_indir_store
  *
  * Purpose:	Store native information into record for v2 B-tree
  *
@@ -446,18 +602,18 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_indir_store(void *nrecord, const void *udata)
+H5HF_huge_bt2_filt_indir_store(void *nrecord, const void *udata)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_indir_store)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_indir_store)
 
     *(H5HF_huge_bt2_filt_indir_rec_t *)nrecord = *(const H5HF_huge_bt2_filt_indir_rec_t *)udata;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_indir_store() */
+} /* H5HF_huge_bt2_filt_indir_store() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_indir_compare
+ * Function:	H5HF_huge_bt2_filt_indir_compare
  *
  * Purpose:	Compare two native information records, according to some key
  *
@@ -471,25 +627,25 @@ H5HF_huge_btree2_filt_indir_store(void *nrecord, const void *udata)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_indir_compare(const void *_rec1, const void *_rec2)
+H5HF_huge_bt2_filt_indir_compare(const void *_rec1, const void *_rec2)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_indir_compare)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_indir_compare)
 
 #ifdef QAK
 {
 const H5HF_huge_bt2_filt_indir_rec_t *rec1 = (const H5HF_huge_bt2_filt_indir_rec_t *)_rec1;
 const H5HF_huge_bt2_filt_indir_rec_t *rec2 = (const H5HF_huge_bt2_filt_indir_rec_t *)_rec2;
 
-HDfprintf(stderr, "%s: rec1 = {%a, %Hu, %x, %Hu, %Hu}\n", "H5HF_huge_btree2_filt_indir_compare", rec1->addr, rec1->len, rec1->filter_mask, rec1->obj_size, rec1->id);
-HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu, %Hu}\n", "H5HF_huge_btree2_filt_indir_compare", rec2->addr, rec2->len, rec2->filter_mask, rec2->obj_size, rec2->id);
+HDfprintf(stderr, "%s: rec1 = {%a, %Hu, %x, %Hu, %Hu}\n", "H5HF_huge_bt2_filt_indir_compare", rec1->addr, rec1->len, rec1->filter_mask, rec1->obj_size, rec1->id);
+HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu, %Hu}\n", "H5HF_huge_bt2_filt_indir_compare", rec2->addr, rec2->len, rec2->filter_mask, rec2->obj_size, rec2->id);
 }
 #endif /* QAK */
     FUNC_LEAVE_NOAPI((herr_t)(((const H5HF_huge_bt2_filt_indir_rec_t *)_rec1)->id - ((const H5HF_huge_bt2_filt_indir_rec_t *)_rec2)->id))
-} /* H5HF_huge_btree2_filt_indir_compare() */
+} /* H5HF_huge_bt2_filt_indir_compare() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_indir_encode
+ * Function:	H5HF_huge_bt2_filt_indir_encode
  *
  * Purpose:	Encode native information into raw form for storing on disk
  *
@@ -502,25 +658,29 @@ HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu, %Hu}\n", "H5HF_huge_btree2_filt
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_indir_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord)
+H5HF_huge_bt2_filt_indir_encode(uint8_t *raw, const void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     const H5HF_huge_bt2_filt_indir_rec_t *nrecord = (const H5HF_huge_bt2_filt_indir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_indir_encode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_indir_encode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Encode the record's fields */
-    H5F_addr_encode(f, &raw, nrecord->addr);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->len);
+    H5F_addr_encode_len(ctx->sizeof_addr, &raw, nrecord->addr);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
     UINT32ENCODE(raw, nrecord->filter_mask);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->obj_size);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->id);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->obj_size, ctx->sizeof_size);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->id, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_indir_encode() */
+} /* H5HF_huge_bt2_filt_indir_encode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_indir_decode
+ * Function:	H5HF_huge_bt2_filt_indir_decode
  *
  * Purpose:	Decode raw disk form of record into native form
  *
@@ -533,25 +693,29 @@ H5HF_huge_btree2_filt_indir_encode(const H5F_t *f, uint8_t *raw, const void *_nr
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_indir_decode(const H5F_t *f, const uint8_t *raw, void *_nrecord)
+H5HF_huge_bt2_filt_indir_decode(const uint8_t *raw, void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     H5HF_huge_bt2_filt_indir_rec_t *nrecord = (H5HF_huge_bt2_filt_indir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_indir_decode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_indir_decode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Decode the record's fields */
-    H5F_addr_decode(f, &raw, &nrecord->addr);
-    H5F_DECODE_LENGTH(f, raw, nrecord->len);
+    H5F_addr_decode_len(ctx->sizeof_addr, &raw, &nrecord->addr);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
     UINT32DECODE(raw, nrecord->filter_mask);
-    H5F_DECODE_LENGTH(f, raw, nrecord->obj_size);
-    H5F_DECODE_LENGTH(f, raw, nrecord->id);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->obj_size, ctx->sizeof_size);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->id, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_indir_decode() */
+} /* H5HF_huge_bt2_filt_indir_decode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_indir_debug
+ * Function:	H5HF_huge_bt2_filt_indir_debug
  *
  * Purpose:	Debug native form of record
  *
@@ -564,19 +728,19 @@ H5HF_huge_btree2_filt_indir_decode(const H5F_t *f, const uint8_t *raw, void *_nr
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_indir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
+H5HF_huge_bt2_filt_indir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
     int indent, int fwidth, const void *_nrecord,
     const void UNUSED *_udata)
 {
     const H5HF_huge_bt2_filt_indir_rec_t *nrecord = (const H5HF_huge_bt2_filt_indir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_indir_debug)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_indir_debug)
 
     HDfprintf(stream, "%*s%-*s {%a, %Hu, %x, %Hu, %Hu}\n", indent, "", fwidth, "Record:",
         nrecord->addr, nrecord->len, nrecord->filter_mask, nrecord->obj_size, nrecord->id);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_indir_debug() */
+} /* H5HF_huge_bt2_filt_indir_debug() */
 
 
 /*-------------------------------------------------------------------------
@@ -614,7 +778,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_dir_store
+ * Function:	H5HF_huge_bt2_dir_store
  *
  * Purpose:	Store native information into record for v2 B-tree
  *
@@ -627,18 +791,18 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_dir_store(void *nrecord, const void *udata)
+H5HF_huge_bt2_dir_store(void *nrecord, const void *udata)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_dir_store)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_dir_store)
 
     *(H5HF_huge_bt2_dir_rec_t *)nrecord = *(const H5HF_huge_bt2_dir_rec_t *)udata;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_dir_store() */
+} /* H5HF_huge_bt2_dir_store() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_dir_compare
+ * Function:	H5HF_huge_bt2_dir_compare
  *
  * Purpose:	Compare two native information records, according to some key
  *
@@ -652,17 +816,17 @@ H5HF_huge_btree2_dir_store(void *nrecord, const void *udata)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_dir_compare(const void *_rec1, const void *_rec2)
+H5HF_huge_bt2_dir_compare(const void *_rec1, const void *_rec2)
 {
     const H5HF_huge_bt2_dir_rec_t *rec1 = (const H5HF_huge_bt2_dir_rec_t *)_rec1;
     const H5HF_huge_bt2_dir_rec_t *rec2 = (const H5HF_huge_bt2_dir_rec_t *)_rec2;
     herr_t ret_value;           /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_dir_compare)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_dir_compare)
 
 #ifdef QAK
-HDfprintf(stderr, "%s: rec1 = {%a, %Hu}\n", "H5HF_huge_btree2_dir_compare", rec1->addr, rec1->len);
-HDfprintf(stderr, "%s: rec2 = {%a, %Hu}\n", "H5HF_huge_btree2_dir_compare", rec2->addr, rec2->len);
+HDfprintf(stderr, "%s: rec1 = {%a, %Hu}\n", "H5HF_huge_bt2_dir_compare", rec1->addr, rec1->len);
+HDfprintf(stderr, "%s: rec2 = {%a, %Hu}\n", "H5HF_huge_bt2_dir_compare", rec2->addr, rec2->len);
 #endif /* QAK */
     if(rec1->addr < rec2->addr)
         ret_value = -1;
@@ -676,11 +840,11 @@ HDfprintf(stderr, "%s: rec2 = {%a, %Hu}\n", "H5HF_huge_btree2_dir_compare", rec2
         ret_value = 0;
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* H5HF_huge_btree2_dir_compare() */
+} /* H5HF_huge_bt2_dir_compare() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_dir_encode
+ * Function:	H5HF_huge_bt2_dir_encode
  *
  * Purpose:	Encode native information into raw form for storing on disk
  *
@@ -693,22 +857,26 @@ HDfprintf(stderr, "%s: rec2 = {%a, %Hu}\n", "H5HF_huge_btree2_dir_compare", rec2
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_dir_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord)
+H5HF_huge_bt2_dir_encode(uint8_t *raw, const void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     const H5HF_huge_bt2_dir_rec_t *nrecord = (const H5HF_huge_bt2_dir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_dir_encode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_dir_encode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Encode the record's fields */
-    H5F_addr_encode(f, &raw, nrecord->addr);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->len);
+    H5F_addr_encode_len(ctx->sizeof_addr, &raw, nrecord->addr);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_dir_encode() */
+} /* H5HF_huge_bt2_dir_encode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_dir_decode
+ * Function:	H5HF_huge_bt2_dir_decode
  *
  * Purpose:	Decode raw disk form of record into native form
  *
@@ -721,22 +889,26 @@ H5HF_huge_btree2_dir_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_dir_decode(const H5F_t *f, const uint8_t *raw, void *_nrecord)
+H5HF_huge_bt2_dir_decode(const uint8_t *raw, void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     H5HF_huge_bt2_dir_rec_t *nrecord = (H5HF_huge_bt2_dir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_dir_decode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_dir_decode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Decode the record's fields */
-    H5F_addr_decode(f, &raw, &nrecord->addr);
-    H5F_DECODE_LENGTH(f, raw, nrecord->len);
+    H5F_addr_decode_len(ctx->sizeof_addr, &raw, &nrecord->addr);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_dir_decode() */
+} /* H5HF_huge_bt2_dir_decode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_dir_debug
+ * Function:	H5HF_huge_bt2_dir_debug
  *
  * Purpose:	Debug native form of record
  *
@@ -749,19 +921,19 @@ H5HF_huge_btree2_dir_decode(const H5F_t *f, const uint8_t *raw, void *_nrecord)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_dir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
+H5HF_huge_bt2_dir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
     int indent, int fwidth, const void *_nrecord,
     const void UNUSED *_udata)
 {
     const H5HF_huge_bt2_dir_rec_t *nrecord = (const H5HF_huge_bt2_dir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_dir_debug)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_dir_debug)
 
     HDfprintf(stream, "%*s%-*s {%a, %Hu}\n", indent, "", fwidth, "Record:",
         nrecord->addr, nrecord->len);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_dir_debug() */
+} /* H5HF_huge_bt2_dir_debug() */
 
 
 /*-------------------------------------------------------------------------
@@ -831,7 +1003,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_dir_store
+ * Function:	H5HF_huge_bt2_filt_dir_store
  *
  * Purpose:	Store native information into record for v2 B-tree
  *
@@ -844,18 +1016,18 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_dir_store(void *nrecord, const void *udata)
+H5HF_huge_bt2_filt_dir_store(void *nrecord, const void *udata)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_dir_store)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_dir_store)
 
     *(H5HF_huge_bt2_filt_dir_rec_t *)nrecord = *(const H5HF_huge_bt2_filt_dir_rec_t *)udata;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_dir_store() */
+} /* H5HF_huge_bt2_filt_dir_store() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_dir_compare
+ * Function:	H5HF_huge_bt2_filt_dir_compare
  *
  * Purpose:	Compare two native information records, according to some key
  *
@@ -869,17 +1041,17 @@ H5HF_huge_btree2_filt_dir_store(void *nrecord, const void *udata)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_dir_compare(const void *_rec1, const void *_rec2)
+H5HF_huge_bt2_filt_dir_compare(const void *_rec1, const void *_rec2)
 {
     const H5HF_huge_bt2_filt_dir_rec_t *rec1 = (const H5HF_huge_bt2_filt_dir_rec_t *)_rec1;
     const H5HF_huge_bt2_filt_dir_rec_t *rec2 = (const H5HF_huge_bt2_filt_dir_rec_t *)_rec2;
     herr_t ret_value;           /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_dir_compare)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_dir_compare)
 
 #ifdef QAK
-HDfprintf(stderr, "%s: rec1 = {%a, %Hu, %x, %Hu}\n", "H5HF_huge_btree2_filt_dir_compare", rec1->addr, rec1->len, rec1->filter_mask, rec1->obj_size);
-HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu}\n", "H5HF_huge_btree2_filt_dir_compare", rec2->addr, rec2->len, rec2->filter_mask, rec2->obj_size);
+HDfprintf(stderr, "%s: rec1 = {%a, %Hu, %x, %Hu}\n", "H5HF_huge_bt2_filt_dir_compare", rec1->addr, rec1->len, rec1->filter_mask, rec1->obj_size);
+HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu}\n", "H5HF_huge_bt2_filt_dir_compare", rec2->addr, rec2->len, rec2->filter_mask, rec2->obj_size);
 #endif /* QAK */
     if(rec1->addr < rec2->addr)
         ret_value = -1;
@@ -893,11 +1065,11 @@ HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu}\n", "H5HF_huge_btree2_filt_dir_
         ret_value = 0;
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* H5HF_huge_btree2_filt_dir_compare() */
+} /* H5HF_huge_bt2_filt_dir_compare() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_dir_encode
+ * Function:	H5HF_huge_bt2_filt_dir_encode
  *
  * Purpose:	Encode native information into raw form for storing on disk
  *
@@ -910,24 +1082,28 @@ HDfprintf(stderr, "%s: rec2 = {%a, %Hu, %x, %Hu}\n", "H5HF_huge_btree2_filt_dir_
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_dir_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord)
+H5HF_huge_bt2_filt_dir_encode(uint8_t *raw, const void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     const H5HF_huge_bt2_filt_dir_rec_t *nrecord = (const H5HF_huge_bt2_filt_dir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_dir_encode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_dir_encode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Encode the record's fields */
-    H5F_addr_encode(f, &raw, nrecord->addr);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->len);
+    H5F_addr_encode_len(ctx->sizeof_addr, &raw, nrecord->addr);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
     UINT32ENCODE(raw, nrecord->filter_mask);
-    H5F_ENCODE_LENGTH(f, raw, nrecord->obj_size);
+    H5F_ENCODE_LENGTH_LEN(raw, nrecord->obj_size, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_dir_encode() */
+} /* H5HF_huge_bt2_filt_dir_encode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_dir_decode
+ * Function:	H5HF_huge_bt2_filt_dir_decode
  *
  * Purpose:	Decode raw disk form of record into native form
  *
@@ -940,24 +1116,28 @@ H5HF_huge_btree2_filt_dir_encode(const H5F_t *f, uint8_t *raw, const void *_nrec
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_dir_decode(const H5F_t *f, const uint8_t *raw, void *_nrecord)
+H5HF_huge_bt2_filt_dir_decode(const uint8_t *raw, void *_nrecord, void *_ctx)
 {
+    H5HF_huge_bt2_ctx_t *ctx = (H5HF_huge_bt2_ctx_t *)_ctx;       /* Callback context structure */
     H5HF_huge_bt2_filt_dir_rec_t *nrecord = (H5HF_huge_bt2_filt_dir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_dir_decode)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_dir_decode)
+
+    /* Sanity check */
+    HDassert(ctx);
 
     /* Decode the record's fields */
-    H5F_addr_decode(f, &raw, &nrecord->addr);
-    H5F_DECODE_LENGTH(f, raw, nrecord->len);
+    H5F_addr_decode_len(ctx->sizeof_addr, &raw, &nrecord->addr);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->len, ctx->sizeof_size);
     UINT32DECODE(raw, nrecord->filter_mask);
-    H5F_DECODE_LENGTH(f, raw, nrecord->obj_size);
+    H5F_DECODE_LENGTH_LEN(raw, nrecord->obj_size, ctx->sizeof_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_dir_decode() */
+} /* H5HF_huge_bt2_filt_dir_decode() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5HF_huge_btree2_filt_dir_debug
+ * Function:	H5HF_huge_bt2_filt_dir_debug
  *
  * Purpose:	Debug native form of record
  *
@@ -970,16 +1150,16 @@ H5HF_huge_btree2_filt_dir_decode(const H5F_t *f, const uint8_t *raw, void *_nrec
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5HF_huge_btree2_filt_dir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
+H5HF_huge_bt2_filt_dir_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
     int indent, int fwidth, const void *_nrecord, const void UNUSED *_udata)
 {
     const H5HF_huge_bt2_filt_dir_rec_t *nrecord = (const H5HF_huge_bt2_filt_dir_rec_t *)_nrecord;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_btree2_filt_dir_debug)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5HF_huge_bt2_filt_dir_debug)
 
     HDfprintf(stream, "%*s%-*s {%a, %Hu, %x, %Hu}\n", indent, "", fwidth, "Record:",
         nrecord->addr, nrecord->len, nrecord->filter_mask, nrecord->obj_size);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* H5HF_huge_btree2_filt_dir_debug() */
+} /* H5HF_huge_bt2_filt_dir_debug() */
 
diff --git a/src/H5HFhuge.c b/src/H5HFhuge.c
index 353ceb3..5490c22 100644
--- a/src/H5HFhuge.c
+++ b/src/H5HFhuge.c
@@ -128,12 +128,12 @@ H5HF_huge_bt2_create(H5HF_hdr_t *hdr, hid_t dxpl_id)
                 + hdr->sizeof_size          /* Length of object */
                 + 4                         /* Filter mask for filtered object */
                 + hdr->sizeof_size);        /* Size of de-filtered object in memory */
-            bt2_cparam.cls = H5HF_BT2_FILT_DIR;
+            bt2_cparam.cls = H5HF_HUGE_BT2_FILT_DIR;
         } /* end if */
         else {
             bt2_cparam.rrec_size = (size_t)(hdr->sizeof_addr    /* Address of object */
                 + hdr->sizeof_size);         /* Length of object */
-            bt2_cparam.cls = H5HF_BT2_DIR;
+            bt2_cparam.cls = H5HF_HUGE_BT2_DIR;
         } /* end else */
     } /* end if */
     else {
@@ -143,13 +143,13 @@ H5HF_huge_bt2_create(H5HF_hdr_t *hdr, hid_t dxpl_id)
                 + 4                         /* Filter mask for filtered object */
                 + hdr->sizeof_size          /* Size of de-filtered object in memory */
                 + hdr->sizeof_size);        /* Unique ID for object */
-            bt2_cparam.cls = H5HF_BT2_FILT_INDIR;
+            bt2_cparam.cls = H5HF_HUGE_BT2_FILT_INDIR;
         } /* end if */
         else {
             bt2_cparam.rrec_size = (size_t)(hdr->sizeof_addr    /* Address of object */
                 + hdr->sizeof_size          /* Length of object */
                 + hdr->sizeof_size);        /* Unique ID for object */
-            bt2_cparam.cls = H5HF_BT2_INDIR;
+            bt2_cparam.cls = H5HF_HUGE_BT2_INDIR;
         } /* end else */
     } /* end else */
     bt2_cparam.node_size = (size_t)H5HF_HUGE_BT2_NODE_SIZE;
@@ -157,7 +157,7 @@ H5HF_huge_bt2_create(H5HF_hdr_t *hdr, hid_t dxpl_id)
     bt2_cparam.merge_percent = H5HF_HUGE_BT2_MERGE_PERC;
 
     /* Create v2 B-tree for tracking 'huge' objects */
-    if(NULL == (hdr->huge_bt2 = H5B2_create(hdr->f, dxpl_id, &bt2_cparam)))
+    if(NULL == (hdr->huge_bt2 = H5B2_create(hdr->f, dxpl_id, &bt2_cparam, hdr->f)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTCREATE, FAIL, "can't create v2 B-tree for tracking 'huge' heap objects")
 
     /* Retrieve the v2 B-tree's address in the file */
@@ -339,7 +339,7 @@ HDfprintf(stderr, "%s: obj_size = %Zu\n", FUNC, obj_size);
         /* Check if v2 B-tree is open yet */
         if(NULL == hdr->huge_bt2) {
             /* Open existing v2 B-tree */
-            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr)))
+            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f)))
                 HGOTO_ERROR(H5E_HEAP, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for tracking 'huge' heap objects")
         } /* end if */
     } /* end else */
@@ -545,7 +545,7 @@ H5HF_huge_get_obj_len(H5HF_hdr_t *hdr, hid_t dxpl_id, const uint8_t *id,
         /* Check if v2 B-tree is open yet */
         if(NULL == hdr->huge_bt2) {
             /* Open existing v2 B-tree */
-            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr)))
+            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f)))
                 HGOTO_ERROR(H5E_HEAP, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for tracking 'huge' heap objects")
         } /* end if */
 
@@ -636,7 +636,7 @@ H5HF_huge_op_real(H5HF_hdr_t *hdr, hid_t dxpl_id, const uint8_t *id,
         /* Check if v2 B-tree is open yet */
         if(NULL == hdr->huge_bt2) {
             /* Open existing v2 B-tree */
-            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr)))
+            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f)))
                 HGOTO_ERROR(H5E_HEAP, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for tracking 'huge' heap objects")
         } /* end if */
 
@@ -784,7 +784,7 @@ H5HF_huge_write(H5HF_hdr_t *hdr, hid_t dxpl_id, const uint8_t *id,
         /* Check if v2 B-tree is open yet */
         if(NULL == hdr->huge_bt2) {
             /* Open existing v2 B-tree */
-            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr)))
+            if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f)))
                 HGOTO_ERROR(H5E_HEAP, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for tracking 'huge' heap objects")
         } /* end if */
 
@@ -914,7 +914,7 @@ H5HF_huge_remove(H5HF_hdr_t *hdr, hid_t dxpl_id, const uint8_t *id)
     /* Check if v2 B-tree is open yet */
     if(NULL == hdr->huge_bt2) {
         /* Open existing v2 B-tree */
-        if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr)))
+        if(NULL == (hdr->huge_bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for tracking 'huge' heap objects")
     } /* end if */
 
@@ -1037,7 +1037,7 @@ H5HF_huge_term(H5HF_hdr_t *hdr, hid_t dxpl_id)
 
         /* Delete the v2 B-tree */
         /* (any v2 B-tree class will work here) */
-        if(H5B2_delete(hdr->f, dxpl_id, hdr->huge_bt2_addr, NULL, NULL) < 0)
+        if(H5B2_delete(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f, NULL, NULL) < 0)
             HGOTO_ERROR(H5E_HEAP, H5E_CANTDELETE, FAIL, "can't delete v2 B-tree")
 
         /* Reset the information about 'huge' objects in the file */
@@ -1105,7 +1105,7 @@ H5HF_huge_delete(H5HF_hdr_t *hdr, hid_t dxpl_id)
     } /* end else */
 
     /* Delete the v2 B-tree */
-    if(H5B2_delete(hdr->f, dxpl_id, hdr->huge_bt2_addr, op, &udata) < 0)
+    if(H5B2_delete(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f, op, &udata) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTDELETE, FAIL, "can't delete v2 B-tree")
 
 done:
diff --git a/src/H5HFpkg.h b/src/H5HFpkg.h
index dac6d39..3c5567c 100644
--- a/src/H5HFpkg.h
+++ b/src/H5HFpkg.h
@@ -481,16 +481,16 @@ H5_DLLVAR const H5AC_class_t H5AC_FHEAP_IBLOCK[1];
 H5_DLLVAR const H5AC_class_t H5AC_FHEAP_DBLOCK[1];
 
 /* The v2 B-tree class for tracking indirectly accessed 'huge' objects */
-H5_DLLVAR const H5B2_class_t H5HF_BT2_INDIR[1];
+H5_DLLVAR const H5B2_class_t H5HF_HUGE_BT2_INDIR[1];
 
 /* The v2 B-tree class for tracking indirectly accessed filtered 'huge' objects */
-H5_DLLVAR const H5B2_class_t H5HF_BT2_FILT_INDIR[1];
+H5_DLLVAR const H5B2_class_t H5HF_HUGE_BT2_FILT_INDIR[1];
 
 /* The v2 B-tree class for tracking directly accessed 'huge' objects */
-H5_DLLVAR const H5B2_class_t H5HF_BT2_DIR[1];
+H5_DLLVAR const H5B2_class_t H5HF_HUGE_BT2_DIR[1];
 
 /* The v2 B-tree class for tracking directly accessed filtered 'huge' objects */
-H5_DLLVAR const H5B2_class_t H5HF_BT2_FILT_DIR[1];
+H5_DLLVAR const H5B2_class_t H5HF_HUGE_BT2_FILT_DIR[1];
 
 /* H5HF single section inherits serializable properties from H5FS_section_class_t */
 H5_DLLVAR H5FS_section_class_t H5HF_FSPACE_SECT_CLS_SINGLE[1];
diff --git a/src/H5HFstat.c b/src/H5HFstat.c
index fb535b9..2ab5240 100644
--- a/src/H5HFstat.c
+++ b/src/H5HFstat.c
@@ -155,7 +155,7 @@ H5HF_size(const H5HF_t *fh, hid_t dxpl_id, hsize_t *heap_size)
     /* Check for B-tree storage of huge objects in fractal heap */
     if(H5F_addr_defined(hdr->huge_bt2_addr)) {
         /* Open the huge object index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr)))
+        if(NULL == (bt2 = H5B2_open(hdr->f, dxpl_id, hdr->huge_bt2_addr, hdr->f)))
             HGOTO_ERROR(H5E_HEAP, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for tracking 'huge' objects")
 
         /* Get the B-tree storage */
diff --git a/src/H5Oattribute.c b/src/H5Oattribute.c
index c624ee1..67d0a92 100644
--- a/src/H5Oattribute.c
+++ b/src/H5Oattribute.c
@@ -1881,7 +1881,7 @@ H5O_attr_bh_info(H5F_t *f, hid_t dxpl_id, H5O_t *oh, H5_ih_info_t *bh_info)
             /* Check if name index available */
             if(H5F_addr_defined(ainfo.name_bt2_addr)) {
                 /* Open the name index v2 B-tree */
-                if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo.name_bt2_addr)))
+                if(NULL == (bt2_name = H5B2_open(f, dxpl_id, ainfo.name_bt2_addr, NULL)))
                     HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
                 /* Get name index B-tree size */
@@ -1892,7 +1892,7 @@ H5O_attr_bh_info(H5F_t *f, hid_t dxpl_id, H5O_t *oh, H5_ih_info_t *bh_info)
             /* Check if creation order index available */
             if(H5F_addr_defined(ainfo.corder_bt2_addr)) {
                 /* Open the creation order index v2 B-tree */
-                if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, ainfo.corder_bt2_addr)))
+                if(NULL == (bt2_corder = H5B2_open(f, dxpl_id, ainfo.corder_bt2_addr, NULL)))
                     HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
                 /* Get creation order index B-tree size */
diff --git a/src/H5Otest.c b/src/H5Otest.c
index 45ade3a..c7cd8a9 100644
--- a/src/H5Otest.c
+++ b/src/H5Otest.c
@@ -194,7 +194,7 @@ H5O_is_attr_empty_test(hid_t oid)
                 HDassert(nattrs == 0);
 
                 /* Open the name index v2 B-tree */
-                if(NULL == (bt2_name = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.name_bt2_addr)))
+                if(NULL == (bt2_name = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.name_bt2_addr, NULL)))
                     HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
                 /* Retrieve # of records in name index */
@@ -281,7 +281,7 @@ H5O_num_attrs_test(hid_t oid, hsize_t *nattrs)
             HDassert(obj_nattrs == 0);
 
             /* Open the name index v2 B-tree */
-            if(NULL == (bt2_name = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.name_bt2_addr)))
+            if(NULL == (bt2_name = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.name_bt2_addr, NULL)))
                 HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
             /* Retrieve # of records in name index */
@@ -363,7 +363,7 @@ H5O_attr_dense_info_test(hid_t oid, hsize_t *name_count, hsize_t *corder_count)
         HGOTO_DONE(FAIL)
 
     /* Open the name index v2 B-tree */
-    if(NULL == (bt2_name = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.name_bt2_addr)))
+    if(NULL == (bt2_name = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.name_bt2_addr, NULL)))
         HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for name index")
 
     /* Retrieve # of records in name index */
@@ -373,7 +373,7 @@ H5O_attr_dense_info_test(hid_t oid, hsize_t *name_count, hsize_t *corder_count)
     /* Check if there is a creation order index */
     if(H5F_addr_defined(ainfo.corder_bt2_addr)) {
         /* Open the creation order index v2 B-tree */
-        if(NULL == (bt2_corder = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.corder_bt2_addr)))
+        if(NULL == (bt2_corder = H5B2_open(oloc->file, H5AC_ind_dxpl_id, ainfo.corder_bt2_addr, NULL)))
             HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for creation order index")
 
         /* Retrieve # of records in creation order index */
diff --git a/src/H5SM.c b/src/H5SM.c
index 7a678cb..cbb063b 100755
--- a/src/H5SM.c
+++ b/src/H5SM.c
@@ -43,6 +43,7 @@
 /******************/
 /* Local Typedefs */
 /******************/
+
 /* Udata struct for calls to H5SM_read_iter_op */
 typedef struct H5SM_read_udata_t {
     H5F_t *file;                    /* File in which sharing is happening (in) */
@@ -475,7 +476,7 @@ H5SM_create_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id)
         bt2_cparam.rrec_size = (size_t)H5SM_SOHM_ENTRY_SIZE(f);
         bt2_cparam.split_percent = H5SM_B2_SPLIT_PERCENT;
         bt2_cparam.merge_percent = H5SM_B2_MERGE_PERCENT;
-        if(NULL == (bt2 = H5B2_create(f, dxpl_id, &bt2_cparam)))
+        if(NULL == (bt2 = H5B2_create(f, dxpl_id, &bt2_cparam, f)))
             HGOTO_ERROR(H5E_SOHM, H5E_CANTCREATE, FAIL, "B-tree creation failed for SOHM index")
 
         /* Retrieve the v2 B-tree's address in the file */
@@ -575,7 +576,7 @@ H5SM_delete_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id,
         HDassert(header->index_type == H5SM_BTREE);
 
         /* Delete the B-tree. */
-        if(H5B2_delete(f, dxpl_id, header->index_addr, NULL, NULL) < 0)
+        if(H5B2_delete(f, dxpl_id, header->index_addr, f, NULL, NULL) < 0)
             HGOTO_ERROR(H5E_SOHM, H5E_CANTDELETE, FAIL, "unable to delete B-tree")
 
         /* Revert to list unless B-trees can have zero records */
@@ -721,7 +722,7 @@ H5SM_convert_list_to_btree(H5F_t *f, H5SM_index_header_t *header,
     bt2_cparam.rrec_size = (size_t)H5SM_SOHM_ENTRY_SIZE(f);
     bt2_cparam.split_percent = H5SM_B2_SPLIT_PERCENT;
     bt2_cparam.merge_percent = H5SM_B2_MERGE_PERCENT;
-    if(NULL == (bt2 = H5B2_create(f, dxpl_id, &bt2_cparam)))
+    if(NULL == (bt2 = H5B2_create(f, dxpl_id, &bt2_cparam, f)))
         HGOTO_ERROR(H5E_SOHM, H5E_CANTCREATE, FAIL, "B-tree creation failed for SOHM index")
 
     /* Retrieve the v2 B-tree's address in the file */
@@ -828,7 +829,7 @@ H5SM_convert_btree_to_list(H5F_t * f, H5SM_index_header_t * header, hid_t dxpl_i
     /* Delete the B-tree and have messages copy themselves to the
      * list as they're deleted
      */
-    if(H5B2_delete(f, dxpl_id, btree_addr, H5SM_btree_convert_to_list_op, list) < 0)
+    if(H5B2_delete(f, dxpl_id, btree_addr, f, H5SM_bt2_convert_to_list_op, list) < 0)
         HGOTO_ERROR(H5E_SOHM, H5E_CANTDELETE, FAIL, "unable to delete B-tree")
 
 done:
@@ -1250,7 +1251,7 @@ H5SM_write_mesg(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
         HDassert(header->index_type == H5SM_BTREE);
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr, f)))
             HGOTO_ERROR(H5E_SOHM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for SOHM index")
 
         /* Set up callback info */
@@ -1344,7 +1345,7 @@ H5SM_write_mesg(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
 
             /* Open the index v2 B-tree, if it isn't already */
             if(NULL == bt2) {
-                if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr)))
+                if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr, f)))
                     HGOTO_ERROR(H5E_SOHM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for SOHM index")
             } /* end if */
 
@@ -1703,7 +1704,7 @@ H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
         HDassert(header->index_type == H5SM_BTREE);
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr, f)))
             HGOTO_ERROR(H5E_SOHM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for SOHM index")
 
         /* If this returns failure, it means that the message wasn't found.
@@ -1733,7 +1734,7 @@ H5SM_delete_from_index(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
         else {
             /* Open the index v2 B-tree, if it isn't already */
             if(NULL == bt2) {
-                if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr)))
+                if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr, f)))
                     HGOTO_ERROR(H5E_SOHM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for SOHM index")
             } /* end if */
 
@@ -1909,86 +1910,6 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5SM_message_encode
- *
- * Purpose:	Serialize a H5SM_sohm_t struct into a buffer RAW.
- *
- * Return:	Non-negative on success
- *              Negative on failure
- *
- * Programmer:	James Laird
- *              Monday, November 6, 2006
- *
- *-------------------------------------------------------------------------
- */
-herr_t
-H5SM_message_encode(const H5F_t *f, uint8_t *raw, const void *_nrecord)
-{
-    const H5SM_sohm_t *message = (const H5SM_sohm_t *)_nrecord;
-
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_encode)
-
-    *raw++ = message->location;
-    UINT32ENCODE(raw, message->hash);
-
-    if(message->location == H5SM_IN_HEAP) {
-        UINT32ENCODE(raw, message->u.heap_loc.ref_count);
-        UINT64ENCODE(raw, message->u.heap_loc.fheap_id);
-    } /* end if */
-    else {
-        HDassert(message->location == H5SM_IN_OH);
-
-        *raw++ = 0;     /* reserved (possible flags byte) */
-        *raw++ = (uint8_t)message->msg_type_id;
-        UINT16ENCODE(raw, message->u.mesg_loc.index);
-        H5F_addr_encode(f, &raw, message->u.mesg_loc.oh_addr);
-    } /* end else */
-
-    FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5SM_message_encode */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5SM_message_decode
- *
- * Purpose:	Read an encoded SOHM message from RAW into an H5SM_sohm_t struct.
- *
- * Return:	Non-negative on success
- *              Negative on failure
- *
- * Programmer:	James Laird
- *              Monday, November 6, 2006
- *
- *-------------------------------------------------------------------------
- */
-herr_t
-H5SM_message_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_nrecord)
-{
-    H5SM_sohm_t *message = (H5SM_sohm_t *)_nrecord;
-
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_decode)
-
-    message->location = (H5SM_storage_loc_t)*raw++;
-    UINT32DECODE(raw, message->hash);
-
-    if(message->location == H5SM_IN_HEAP) {
-        UINT32DECODE(raw, message->u.heap_loc.ref_count);
-        UINT64DECODE(raw, message->u.heap_loc.fheap_id);
-    } /* end if */
-    else {
-        HDassert(message->location == H5SM_IN_OH);
-
-        raw++;          /* reserved */
-        message->msg_type_id = *raw++;
-        UINT16DECODE(raw, message->u.mesg_loc.index);
-        H5F_addr_decode(f, &raw, &message->u.mesg_loc.oh_addr);
-    } /* end else */
-
-    FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5SM_message_decode */
-
-
-/*-------------------------------------------------------------------------
  * Function:    H5SM_reconstitute
  *
  * Purpose:     Reconstitute a shared object header message structure from
@@ -2140,7 +2061,7 @@ H5SM_get_refcount(H5F_t *f, hid_t dxpl_id, unsigned type_id,
         HDassert(header->index_type == H5SM_BTREE);
 
         /* Open the index v2 B-tree */
-        if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr)))
+        if(NULL == (bt2 = H5B2_open(f, dxpl_id, header->index_addr, f)))
             HGOTO_ERROR(H5E_SOHM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for SOHM index")
 
         /* Look up the message in the v2 B-tree */
@@ -2586,7 +2507,7 @@ H5SM_ih_size(H5F_t *f, hid_t dxpl_id, hsize_t *hdr_size, H5_ih_info_t *ih_info)
 	if(table->indexes[u].index_type == H5SM_BTREE) {
 	    if(H5F_addr_defined(table->indexes[u].index_addr)) {
                 /* Open the index v2 B-tree */
-                if(NULL == (bt2 = H5B2_open(f, dxpl_id, table->indexes[u].index_addr)))
+                if(NULL == (bt2 = H5B2_open(f, dxpl_id, table->indexes[u].index_addr, f)))
                     HGOTO_ERROR(H5E_SOHM, H5E_CANTOPENOBJ, FAIL, "unable to open v2 B-tree for SOHM index")
 
 		if(H5B2_size(bt2, dxpl_id, &(ih_info->index_size)) < 0)
diff --git a/src/H5SMbtree2.c b/src/H5SMbtree2.c
index 2be7745..95527f9 100755
--- a/src/H5SMbtree2.c
+++ b/src/H5SMbtree2.c
@@ -20,6 +20,7 @@
 #define H5O_PACKAGE		/*suppress error about including H5Opkg 	  */
 #define H5SM_PACKAGE		/*suppress error about including H5SMpkg	  */
 
+
 /***********/
 /* Headers */
 /***********/
@@ -38,23 +39,18 @@
 /* Local Typedefs */
 /******************/
 
-/* Udata struct for calls to H5SM_btree_compare_cb and H5SM_compare_iter_op*/
-typedef struct H5SM_compare_udata_t {
-    const H5SM_mesg_key_t *key; /* Key; compare this against stored message */
-    H5O_msg_crt_idx_t idx;      /* Index of the message in the OH, if applicable */
-    herr_t ret;                 /* Return value; set this to result of memcmp */
-} H5SM_compare_udata_t;
-
 
 /********************/
 /* Local Prototypes */
 /********************/
 
 /* v2 B-tree callbacks */
-static herr_t H5SM_btree_compare_cb(const void *obj, size_t obj_len, void *_udata);
-static herr_t H5SM_btree_store(void *native, const void *udata);
-static herr_t H5SM_btree_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
+static void *H5SM_bt2_crt_context(void *udata);
+static herr_t H5SM_bt2_dst_context(void *ctx);
+static herr_t H5SM_bt2_store(void *native, const void *udata);
+static herr_t H5SM_bt2_debug(FILE *stream, const H5F_t *f, hid_t dxpl_id,
     int indent, int fwidth, const void *record, const void *_udata);
+static void *H5SM_bt2_crt_dbg_context(H5F_t *f, hid_t dxpl_id, haddr_t addr);
 
 
 /*****************************/
@@ -65,221 +61,99 @@ const H5B2_class_t H5SM_INDEX[1]={{   /* B-tree class information */
     H5B2_SOHM_INDEX_ID,               /* Type of B-tree */
     "H5B2_SOHM_INDEX_ID",             /* Name of B-tree class */
     sizeof(H5SM_sohm_t),              /* Size of native record */
-    H5SM_btree_store,                 /* Record storage callback */
+    H5SM_bt2_crt_context,             /* Create client callback context */
+    H5SM_bt2_dst_context,             /* Destroy client callback context */
+    H5SM_bt2_store,                   /* Record storage callback */
     H5SM_message_compare,             /* Record comparison callback */
     H5SM_message_encode,              /* Record encoding callback */
     H5SM_message_decode,              /* Record decoding callback */
-    H5SM_btree_debug                  /* Record debugging callback */
+    H5SM_bt2_debug,                   /* Record debugging callback */
+    H5SM_bt2_crt_dbg_context,	      /* Create debugging context */
+    H5SM_bt2_dst_context 	      /* Destroy debugging context */
 }};
 
+
 /*******************/
 /* Local Variables */
 /*******************/
 
+/* Declare a free list to manage the H5SM_bt2_ctx_t struct */
+H5FL_DEFINE_STATIC(H5SM_bt2_ctx_t);
+
+
 
 /*-------------------------------------------------------------------------
- * Function:	H5SM_btree_compare_cb
- *
- * Purpose:	Callback for H5HF_op, used in H5SM_message_compare below.
- *              Determines whether the search key passed in in _UDATA is
- *              equal to OBJ or not.
+ * Function:	H5SM_bt2_crt_context
  *
- *              Passes back the result in _UDATA->RET
+ * Purpose:	Create client callback context
  *
- * Return:	Negative on error, non-negative on success
+ * Return:	Success:	non-NULL
+ *		Failure:	NULL
  *
- * Programmer:	James Laird
- *              Monday, January 8, 2007
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 26, 2009
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5SM_btree_compare_cb(const void *obj, size_t obj_len, void *_udata)
+static void *
+H5SM_bt2_crt_context(void *_f)
 {
-    H5SM_compare_udata_t *udata = (H5SM_compare_udata_t *)_udata;
+    H5F_t *f = (H5F_t *)_f;     /* User data for building callback context */
+    H5SM_bt2_ctx_t *ctx;        /* Callback context structure */
+    void *ret_value;            /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_compare_cb)
+    FUNC_ENTER_NOAPI_NOINIT(H5SM_bt2_crt_context)
 
-    /* If the encoding sizes are different, it's not the same object */
-    if(udata->key->encoding_size > obj_len)
-        udata->ret = 1;
-    else if(udata->key->encoding_size < obj_len)
-        udata->ret = -1;
-    else
-        /* Sizes are the same.  Return result of memcmp */
-        udata->ret = HDmemcmp(udata->key->encoding, obj, obj_len);
+    /* Sanity check */
+    HDassert(f);
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5SM_btree_compare_cb() */
+    /* Allocate callback context */
+    if(NULL == (ctx = H5FL_MALLOC(H5SM_bt2_ctx_t)))
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate callback context")
 
-
-/*-------------------------------------------------------------------------
- * Function:	H5SM_compare_iter_op
- *
- * Purpose:	OH iteration callback to compare a key against a message in
- *              an OH
- *
- * Return:	0 if this is not the message we're searching for
- *              1 if this is the message we're searching for (with memcmp
- *                      result returned in udata)
- *              negative on error
- *
- * Programmer:	James Laird
- *              Wednesday, February 7, 2007
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5SM_compare_iter_op(H5O_t *oh, H5O_mesg_t *mesg/*in,out*/, unsigned sequence,
-    hbool_t UNUSED *oh_modified, void *_udata/*in,out*/)
-{
-    H5SM_compare_udata_t *udata = (H5SM_compare_udata_t *) _udata;
-    herr_t ret_value = H5_ITER_CONT;
-
-    FUNC_ENTER_NOAPI_NOINIT(H5SM_compare_iter_op)
-
-    /*
-     * Check arguments.
-     */
-    HDassert(oh);
-    HDassert(mesg);
-    HDassert(udata && udata->key);
-
-    /* Check the creation index for this message */
-    if(sequence == udata->idx) {
-        size_t aligned_encoded_size = H5O_ALIGN_OH(oh, udata->key->encoding_size);
-
-        /* Sanity check the message's length */
-        HDassert(mesg->raw_size > 0);
-
-        if(aligned_encoded_size > mesg->raw_size)
-            udata->ret = 1;
-        else if(aligned_encoded_size < mesg->raw_size)
-            udata->ret = -1;
-        else {
-            /* Check if the message is dirty & flush it to the object header if so */
-            if(mesg->dirty)
-                if(H5O_msg_flush(udata->key->file, oh, mesg) < 0)
-                    HGOTO_ERROR(H5E_SOHM, H5E_CANTENCODE, H5_ITER_ERROR, "unable to encode object header message")
-
-            HDassert(udata->key->encoding_size <= mesg->raw_size);
-            udata->ret = HDmemcmp(udata->key->encoding, mesg->raw, udata->key->encoding_size);
-        } /* end else */
-
-        /* Indicate that we found the message we were looking for */
-        ret_value = H5_ITER_STOP;
-    } /* end if */
+    /* Determine the size of addresses & lengths in the file */
+    ctx->sizeof_addr = H5F_SIZEOF_ADDR(f);
+
+    /* Set return value */
+    ret_value = ctx;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5SM_compare_iter_op() */
+} /* H5SM_bt2_crt_context() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5SM_message_compare
+ * Function:	H5SM_bt2_dst_context
  *
- * Purpose:	Determine whether the search key rec1 represents a shared
- *              message that is equal to rec2 or not, and if not, whether
- *              rec1 is "greater than" or "less than" rec2.
+ * Purpose:	Destroy client callback context
  *
- * Return:	0 if rec1 == rec2
- *              Negative if rec1 < rec2
- *              Positive if rec1 > rec2
+ * Return:	Success:	non-negative
+ *		Failure:	negative
  *
- * Programmer:	James Laird
- *              Monday, November 6, 2006
+ * Programmer:	Quincey Koziol
+ *              Thursday, November 26, 2009
  *
  *-------------------------------------------------------------------------
  */
-herr_t
-H5SM_message_compare(const void *rec1, const void *rec2)
+static herr_t
+H5SM_bt2_dst_context(void *_ctx)
 {
-    const H5SM_mesg_key_t *key = (const H5SM_mesg_key_t *) rec1;
-    const H5SM_sohm_t *mesg = (const H5SM_sohm_t *) rec2;
-    herr_t ret_value = 0;
-
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_compare)
-
-    /* If the key has an fheap ID, we're looking for a message that's
-     * already in the index; if the fheap ID matches, we've found the message
-     * and can stop immediately.
-     * Likewise, if the message has an OH location that is matched by the
-     * message in the index, we've found the message.
-     */
-    if(mesg->location == H5SM_IN_HEAP && key->message.location == H5SM_IN_HEAP) {
-        if(key->message.u.heap_loc.fheap_id == mesg->u.heap_loc.fheap_id)
-            HGOTO_DONE(0);
-    } /* end if */
-    else if(mesg->location == H5SM_IN_OH && key->message.location == H5SM_IN_OH) {
-        if(key->message.u.mesg_loc.oh_addr == mesg->u.mesg_loc.oh_addr &&
-                key->message.u.mesg_loc.index == mesg->u.mesg_loc.index &&
-                key->message.msg_type_id == mesg->msg_type_id)
-            HGOTO_DONE(0);
-    } /* end if */
-
-    /* Compare hash values */
-    if(key->message.hash > mesg->hash)
-        ret_value = 1;
-    else if(key->message.hash < mesg->hash)
-        ret_value = -1;
-    /* If the hash values match, make sure the messages are really the same */
-    else {
-        /* Hash values match; compare the encoded message with the one in
-         * the index.
-         */
-        H5SM_compare_udata_t udata;
-        herr_t status;
-
-        HDassert(key->message.hash == mesg->hash);
-        HDassert(key->encoding_size > 0 && key->encoding);
-
-        /* Set up user data for callback */
-        udata.key = key;
-
-        /* Compare the encoded message with either the message in the heap or
-         * the message in an object header.
-         */
-        if(mesg->location == H5SM_IN_HEAP) {
-            /* Call heap op routine with comparison callback */
-            status = H5HF_op(key->fheap, key->dxpl_id, &(mesg->u.heap_loc.fheap_id), H5SM_btree_compare_cb, &udata);
-            HDassert(status >= 0);
-        } /* end if */
-        else {
-            H5O_loc_t oloc;             /* Object owning the message */
-            H5O_mesg_operator_t op;             /* Message operator */
-
-            /* Sanity checks */
-            HDassert(key->file);
-            HDassert(mesg->location == H5SM_IN_OH);
-
-            /* Reset the object location */
-            status = H5O_loc_reset(&oloc);
-            HDassert(status >= 0);
-
-            /* Set up object location */
-            oloc.file = key->file;
-            oloc.addr = mesg->u.mesg_loc.oh_addr;
-
-            /* Finish setting up user data for iterator */
-            udata.idx = mesg->u.mesg_loc.index;
-
-            /* Locate the right message and compare with it */
-            op.op_type = H5O_MESG_OP_LIB;
-            op.u.lib_op = H5SM_compare_iter_op;
-            status = H5O_msg_iterate(&oloc, mesg->msg_type_id, &op, &udata, key->dxpl_id);
-            HDassert(status >= 0);
-        } /* end else */
-
-        ret_value = udata.ret;
-    } /* end if */
+    H5SM_bt2_ctx_t *ctx = (H5SM_bt2_ctx_t *)_ctx;       /* Callback context structure */
 
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5SM_message_compare */
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_bt2_dst_context)
+
+    /* Sanity check */
+    HDassert(ctx);
+
+    /* Release callback context */
+    ctx = H5FL_FREE(H5SM_bt2_ctx_t, ctx);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* H5SM_bt2_dst_context() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5SM_btree_store
+ * Function:	H5SM_bt2_store
  *
  * Purpose:	Store a H5SM_sohm_t SOHM message in the B-tree.  The message
  *              comes in UDATA as a H5SM_mesg_key_t* and is copied to
@@ -294,21 +168,21 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5SM_btree_store(void *native, const void *udata)
+H5SM_bt2_store(void *native, const void *udata)
 {
     const H5SM_mesg_key_t *key = (const H5SM_mesg_key_t *)udata;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_store)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_bt2_store)
 
     /* Copy the source message to the B-tree */
     *(H5SM_sohm_t *)native = key->message;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5SM_btree_store */
+} /* end H5SM_bt2_store */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5SM_btree_debug
+ * Function:	H5SM_bt2_debug
  *
  * Purpose:	Print debugging information for a H5SM_sohm_t.
  *
@@ -321,12 +195,12 @@ H5SM_btree_store(void *native, const void *udata)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5SM_btree_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
+H5SM_bt2_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
     int indent, int fwidth, const void *record, const void UNUSED *_udata)
 {
     const H5SM_sohm_t *sohm = (const H5SM_sohm_t *)record;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_debug)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_bt2_debug)
 
     if(sohm->location == H5SM_IN_HEAP)
         HDfprintf(stream, "%*s%-*s {%a, %lo, %Hx}\n", indent, "", fwidth,
@@ -340,11 +214,51 @@ H5SM_btree_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
     } /* end else */
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5SM_btree_debug */
+} /* end H5SM_bt2_debug */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5SM_bt2_crt_dbg_context
+ *
+ * Purpose:	Create context for debugging callback
+ *
+ * Return:	Success:	non-NULL
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Tuesday, December 1, 2009
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5SM_bt2_crt_dbg_context(H5F_t *f, hid_t UNUSED dxpl_id, haddr_t UNUSED addr)
+{
+    H5SM_bt2_ctx_t *ctx;        /* Callback context structure */
+    void *ret_value;            /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5SM_bt2_crt_dbg_context)
+
+    /* Sanity check */
+    HDassert(f);
+    HDassert(H5F_addr_defined(addr));
+
+    /* Allocate callback context */
+    if(NULL == (ctx = H5FL_MALLOC(H5SM_bt2_ctx_t)))
+        HGOTO_ERROR(H5E_HEAP, H5E_CANTALLOC, NULL, "can't allocate callback context")
+
+    /* Determine the size of addresses & lengths in the file */
+    ctx->sizeof_addr = H5F_SIZEOF_ADDR(f);
+
+    /* Set return value */
+    ret_value = ctx;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5SM_bt2_crt_dbg_context() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5SM_btree_convert_to_list_op
+ * Function:	H5SM_bt2_convert_to_list_op
  *
  * Purpose:	An H5B2_remove_t callback function to convert a SOHM
  *              B-tree index to a list.
@@ -360,13 +274,13 @@ H5SM_btree_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
  *-------------------------------------------------------------------------
  */
 herr_t
-H5SM_btree_convert_to_list_op(const void * record, void *op_data)
+H5SM_bt2_convert_to_list_op(const void * record, void *op_data)
 {
     const H5SM_sohm_t *message = (const H5SM_sohm_t *)record;
     const H5SM_list_t *list = (const H5SM_list_t *)op_data;
     size_t mesg_idx;            /* Index of message to modify */
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_convert_to_list_op)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_bt2_convert_to_list_op)
 
     /* Sanity checks */
     HDassert(record);
@@ -382,5 +296,5 @@ H5SM_btree_convert_to_list_op(const void * record, void *op_data)
     HDmemcpy(&(list->messages[mesg_idx]), message, sizeof(H5SM_sohm_t));
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5SM_btree_convert_to_list_op() */
+} /* end H5SM_bt2_convert_to_list_op() */
 
diff --git a/src/H5SMcache.c b/src/H5SMcache.c
index 9048b9f..1380e71 100644
--- a/src/H5SMcache.c
+++ b/src/H5SMcache.c
@@ -462,6 +462,7 @@ H5SM_list_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *udata1,
 {
     H5SM_list_t *list;          /* The SOHM list being read in */
     H5SM_index_header_t *header = (H5SM_index_header_t *) udata2;     /* Index header for this list */
+    H5SM_bt2_ctx_t ctx;         /* Message encoding context */
     size_t size;                /* Size of SOHM list on disk */
     H5WB_t *wb = NULL;          /* Wrapped buffer for list index data */
     uint8_t lst_buf[H5SM_LST_BUF_SIZE]; /* Buffer for list index */
@@ -512,8 +513,9 @@ H5SM_list_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED *udata1,
     p += H5_SIZEOF_MAGIC;
 
     /* Read messages into the list array */
+    ctx.sizeof_addr = H5F_SIZEOF_ADDR(f);
     for(x = 0; x < header->num_messages; x++) {
-        if(H5SM_message_decode(f, p, &(list->messages[x])) < 0)
+        if(H5SM_message_decode(p, &(list->messages[x]), &ctx) < 0)
             HGOTO_ERROR(H5E_SOHM, H5E_CANTLOAD, NULL, "can't decode shared message")
         p += H5SM_SOHM_ENTRY_SIZE(f);
     } /* end for */
@@ -580,6 +582,7 @@ H5SM_list_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5SM_lis
     HDassert(list->header);
 
     if(list->cache_info.is_dirty) {
+        H5SM_bt2_ctx_t ctx;         /* Message encoding context */
         uint8_t *buf;               /* Temporary buffer */
         uint8_t *p;                 /* Pointer into raw data buffer */
         size_t size;                /* Header size on disk */
@@ -606,9 +609,10 @@ H5SM_list_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5SM_lis
 
         /* Write messages from the messages array to disk */
         mesgs_written = 0;
+        ctx.sizeof_addr = H5F_SIZEOF_ADDR(f);
         for(x = 0; x < list->header->list_max && mesgs_written < list->header->num_messages; x++) {
             if(list->messages[x].location != H5SM_NO_LOC) {
-                if(H5SM_message_encode(f, p, &(list->messages[x])) < 0)
+                if(H5SM_message_encode(p, &(list->messages[x]), &ctx) < 0)
                     HGOTO_ERROR(H5E_SOHM, H5E_CANTFLUSH, FAIL, "unable to write shared message to disk")
 
                 p+=H5SM_SOHM_ENTRY_SIZE(f);
diff --git a/src/H5SMmessage.c b/src/H5SMmessage.c
new file mode 100644
index 0000000..9a214ea
--- /dev/null
+++ b/src/H5SMmessage.c
@@ -0,0 +1,358 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the files COPYING and Copyright.html.  COPYING can be found at the root   *
+ * of the source code distribution tree; Copyright.html can be found at the  *
+ * root level of an installed copy of the electronic HDF5 document set and   *
+ * is linked from the top-level documents page.  It can also be found at     *
+ * http://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
+ * access to either file, you may request a copy from help@hdfgroup.org.     *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/****************/
+/* Module Setup */
+/****************/
+
+#define H5O_PACKAGE		/*suppress error about including H5Opkg 	  */
+#define H5SM_PACKAGE		/*suppress error about including H5SMpkg	  */
+
+
+/***********/
+/* Headers */
+/***********/
+#include "H5private.h"		/* Generic Functions			*/
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5Opkg.h"             /* Object Headers                       */
+#include "H5SMpkg.h"            /* Shared object header messages        */
+
+
+/****************/
+/* Local Macros */
+/****************/
+
+
+/******************/
+/* Local Typedefs */
+/******************/
+
+/* Udata struct for calls to H5SM_compare_cb and H5SM_compare_iter_op*/
+typedef struct H5SM_compare_udata_t {
+    const H5SM_mesg_key_t *key; /* Key; compare this against stored message */
+    H5O_msg_crt_idx_t idx;      /* Index of the message in the OH, if applicable */
+    herr_t ret;                 /* Return value; set this to result of memcmp */
+} H5SM_compare_udata_t;
+
+
+/********************/
+/* Local Prototypes */
+/********************/
+static herr_t H5SM_compare_cb(const void *obj, size_t obj_len, void *udata);
+static herr_t H5SM_compare_iter_op(H5O_t *oh, H5O_mesg_t *mesg, unsigned sequence,
+    hbool_t *oh_modified, void *udata);
+
+
+/*********************/
+/* Package Variables */
+/*********************/
+
+
+/*****************************/
+/* Library Private Variables */
+/*****************************/
+
+
+/*******************/
+/* Local Variables */
+/*******************/
+
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5SM_compare_cb
+ *
+ * Purpose:	Callback for H5HF_op, used in H5SM_message_compare below.
+ *              Determines whether the search key passed in in _UDATA is
+ *              equal to OBJ or not.
+ *
+ *              Passes back the result in _UDATA->RET
+ *
+ * Return:	Negative on error, non-negative on success
+ *
+ * Programmer:	James Laird
+ *              Monday, January 8, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5SM_compare_cb(const void *obj, size_t obj_len, void *_udata)
+{
+    H5SM_compare_udata_t *udata = (H5SM_compare_udata_t *)_udata;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_compare_cb)
+
+    /* If the encoding sizes are different, it's not the same object */
+    if(udata->key->encoding_size > obj_len)
+        udata->ret = 1;
+    else if(udata->key->encoding_size < obj_len)
+        udata->ret = -1;
+    else
+        /* Sizes are the same.  Return result of memcmp */
+        udata->ret = HDmemcmp(udata->key->encoding, obj, obj_len);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5SM_compare_cb() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5SM_compare_iter_op
+ *
+ * Purpose:	OH iteration callback to compare a key against a message in
+ *              an OH
+ *
+ * Return:	0 if this is not the message we're searching for
+ *              1 if this is the message we're searching for (with memcmp
+ *                      result returned in udata)
+ *              negative on error
+ *
+ * Programmer:	James Laird
+ *              Wednesday, February 7, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5SM_compare_iter_op(H5O_t *oh, H5O_mesg_t *mesg/*in,out*/, unsigned sequence,
+    hbool_t UNUSED *oh_modified, void *_udata/*in,out*/)
+{
+    H5SM_compare_udata_t *udata = (H5SM_compare_udata_t *) _udata;
+    herr_t ret_value = H5_ITER_CONT;
+
+    FUNC_ENTER_NOAPI_NOINIT(H5SM_compare_iter_op)
+
+    /*
+     * Check arguments.
+     */
+    HDassert(oh);
+    HDassert(mesg);
+    HDassert(udata && udata->key);
+
+    /* Check the creation index for this message */
+    if(sequence == udata->idx) {
+        size_t aligned_encoded_size = H5O_ALIGN_OH(oh, udata->key->encoding_size);
+
+        /* Sanity check the message's length */
+        HDassert(mesg->raw_size > 0);
+
+        if(aligned_encoded_size > mesg->raw_size)
+            udata->ret = 1;
+        else if(aligned_encoded_size < mesg->raw_size)
+            udata->ret = -1;
+        else {
+            /* Check if the message is dirty & flush it to the object header if so */
+            if(mesg->dirty)
+                if(H5O_msg_flush(udata->key->file, oh, mesg) < 0)
+                    HGOTO_ERROR(H5E_SOHM, H5E_CANTENCODE, H5_ITER_ERROR, "unable to encode object header message")
+
+            HDassert(udata->key->encoding_size <= mesg->raw_size);
+            udata->ret = HDmemcmp(udata->key->encoding, mesg->raw, udata->key->encoding_size);
+        } /* end else */
+
+        /* Indicate that we found the message we were looking for */
+        ret_value = H5_ITER_STOP;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5SM_compare_iter_op() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5SM_message_compare
+ *
+ * Purpose:	Determine whether the search key rec1 represents a shared
+ *              message that is equal to rec2 or not, and if not, whether
+ *              rec1 is "greater than" or "less than" rec2.
+ *
+ * Return:	0 if rec1 == rec2
+ *              Negative if rec1 < rec2
+ *              Positive if rec1 > rec2
+ *
+ * Programmer:	James Laird
+ *              Monday, November 6, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5SM_message_compare(const void *rec1, const void *rec2)
+{
+    const H5SM_mesg_key_t *key = (const H5SM_mesg_key_t *) rec1;
+    const H5SM_sohm_t *mesg = (const H5SM_sohm_t *) rec2;
+    herr_t ret_value = 0;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_compare)
+
+    /* If the key has an fheap ID, we're looking for a message that's
+     * already in the index; if the fheap ID matches, we've found the message
+     * and can stop immediately.
+     * Likewise, if the message has an OH location that is matched by the
+     * message in the index, we've found the message.
+     */
+    if(mesg->location == H5SM_IN_HEAP && key->message.location == H5SM_IN_HEAP) {
+        if(key->message.u.heap_loc.fheap_id == mesg->u.heap_loc.fheap_id)
+            HGOTO_DONE(0);
+    } /* end if */
+    else if(mesg->location == H5SM_IN_OH && key->message.location == H5SM_IN_OH) {
+        if(key->message.u.mesg_loc.oh_addr == mesg->u.mesg_loc.oh_addr &&
+                key->message.u.mesg_loc.index == mesg->u.mesg_loc.index &&
+                key->message.msg_type_id == mesg->msg_type_id)
+            HGOTO_DONE(0);
+    } /* end if */
+
+    /* Compare hash values */
+    if(key->message.hash > mesg->hash)
+        ret_value = 1;
+    else if(key->message.hash < mesg->hash)
+        ret_value = -1;
+    /* If the hash values match, make sure the messages are really the same */
+    else {
+        /* Hash values match; compare the encoded message with the one in
+         * the index.
+         */
+        H5SM_compare_udata_t udata;
+        herr_t status;
+
+        HDassert(key->message.hash == mesg->hash);
+        HDassert(key->encoding_size > 0 && key->encoding);
+
+        /* Set up user data for callback */
+        udata.key = key;
+
+        /* Compare the encoded message with either the message in the heap or
+         * the message in an object header.
+         */
+        if(mesg->location == H5SM_IN_HEAP) {
+            /* Call heap op routine with comparison callback */
+            status = H5HF_op(key->fheap, key->dxpl_id, &(mesg->u.heap_loc.fheap_id), H5SM_compare_cb, &udata);
+            HDassert(status >= 0);
+        } /* end if */
+        else {
+            H5O_loc_t oloc;             /* Object owning the message */
+            H5O_mesg_operator_t op;             /* Message operator */
+
+            /* Sanity checks */
+            HDassert(key->file);
+            HDassert(mesg->location == H5SM_IN_OH);
+
+            /* Reset the object location */
+            status = H5O_loc_reset(&oloc);
+            HDassert(status >= 0);
+
+            /* Set up object location */
+            oloc.file = key->file;
+            oloc.addr = mesg->u.mesg_loc.oh_addr;
+
+            /* Finish setting up user data for iterator */
+            udata.idx = mesg->u.mesg_loc.index;
+
+            /* Locate the right message and compare with it */
+            op.op_type = H5O_MESG_OP_LIB;
+            op.u.lib_op = H5SM_compare_iter_op;
+            status = H5O_msg_iterate(&oloc, mesg->msg_type_id, &op, &udata, key->dxpl_id);
+            HDassert(status >= 0);
+        } /* end else */
+
+        ret_value = udata.ret;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5SM_message_compare */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5SM_message_encode
+ *
+ * Purpose:	Serialize a H5SM_sohm_t struct into a buffer RAW.
+ *
+ * Return:	Non-negative on success
+ *              Negative on failure
+ *
+ * Programmer:	James Laird
+ *              Monday, November 6, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5SM_message_encode(uint8_t *raw, const void *_nrecord, void *_ctx)
+{
+    H5SM_bt2_ctx_t *ctx = (H5SM_bt2_ctx_t *)_ctx;       /* Callback context structure */
+    const H5SM_sohm_t *message = (const H5SM_sohm_t *)_nrecord;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_encode)
+
+    /* Sanity check */
+    HDassert(ctx);
+
+    *raw++ = message->location;
+    UINT32ENCODE(raw, message->hash);
+
+    if(message->location == H5SM_IN_HEAP) {
+        UINT32ENCODE(raw, message->u.heap_loc.ref_count);
+        UINT64ENCODE(raw, message->u.heap_loc.fheap_id);
+    } /* end if */
+    else {
+        HDassert(message->location == H5SM_IN_OH);
+
+        *raw++ = 0;     /* reserved (possible flags byte) */
+        *raw++ = (uint8_t)message->msg_type_id;
+        UINT16ENCODE(raw, message->u.mesg_loc.index);
+        H5F_addr_encode_len(ctx->sizeof_addr, &raw, message->u.mesg_loc.oh_addr);
+    } /* end else */
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5SM_message_encode */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5SM_message_decode
+ *
+ * Purpose:	Read an encoded SOHM message from RAW into an H5SM_sohm_t struct.
+ *
+ * Return:	Non-negative on success
+ *              Negative on failure
+ *
+ * Programmer:	James Laird
+ *              Monday, November 6, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5SM_message_decode(const uint8_t *raw, void *_nrecord, void *_ctx)
+{
+    H5SM_bt2_ctx_t *ctx = (H5SM_bt2_ctx_t *)_ctx;       /* Callback context structure */
+    H5SM_sohm_t *message = (H5SM_sohm_t *)_nrecord;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_decode)
+
+    message->location = (H5SM_storage_loc_t)*raw++;
+    UINT32DECODE(raw, message->hash);
+
+    if(message->location == H5SM_IN_HEAP) {
+        UINT32DECODE(raw, message->u.heap_loc.ref_count);
+        UINT64DECODE(raw, message->u.heap_loc.fheap_id);
+    } /* end if */
+    else {
+        HDassert(message->location == H5SM_IN_OH);
+
+        raw++;          /* reserved */
+        message->msg_type_id = *raw++;
+        UINT16DECODE(raw, message->u.mesg_loc.index);
+        H5F_addr_decode_len(ctx->sizeof_addr, &raw, &message->u.mesg_loc.oh_addr);
+    } /* end else */
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5SM_message_decode */
+
diff --git a/src/H5SMpkg.h b/src/H5SMpkg.h
index 093fb04..64f0ccb 100755
--- a/src/H5SMpkg.h
+++ b/src/H5SMpkg.h
@@ -213,6 +213,11 @@ typedef struct {
     hid_t dxpl_id;
 } H5SM_incr_ref_opdata;
 
+/* v2 B-tree client callback context */
+typedef struct H5SM_bt2_ctx_t {
+    uint8_t     sizeof_addr;    /* Size of file addresses */
+} H5SM_bt2_ctx_t;
+
 
 /****************************/
 /* Package Variables        */
@@ -236,20 +241,12 @@ H5_DLLVAR const H5B2_class_t H5SM_INDEX[1];
 H5_DLL ssize_t H5SM_get_index(const H5SM_master_table_t *table, unsigned type_id);
 
 /* Encode and decode routines, used for B-tree and cache encoding/decoding */
-H5_DLL herr_t H5SM_message_encode(const H5F_t *f, uint8_t *raw,
-    const void *native);
-H5_DLL herr_t H5SM_message_decode(const H5F_t *f, const uint8_t *raw,
-    void *native);
-
-/* Callbacks to give to B-tree traversals */
-/* H5SM_message_compare is in H5SMbtree2.c, but is also used by list code
- * in H5SM.c.
- */
-H5_DLL herr_t H5SM_message_compare(const void *rec1,
-                                   const void *rec2);
+H5_DLL herr_t H5SM_message_compare(const void *rec1, const void *rec2);
+H5_DLL herr_t H5SM_message_encode(uint8_t *raw, const void *native, void *ctx);
+H5_DLL herr_t H5SM_message_decode(const uint8_t *raw, void *native, void *ctx);
 
 /* H5B2_remove_t callback to add messages to a list index */
-H5_DLL herr_t H5SM_btree_convert_to_list_op(const void * record, void *op_data);
+H5_DLL herr_t H5SM_bt2_convert_to_list_op(const void * record, void *op_data);
 
 /* Fractal heap 'op' callback to compute hash value for message "in place" */
 H5_DLL herr_t H5SM_get_hash_fh_cb(const void *obj, size_t obj_len, void *_udata);
diff --git a/src/Makefile.am b/src/Makefile.am
index bc5e1ce..b71033e 100755
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -92,8 +92,10 @@ libhdf5_la_SOURCES= H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5RC.c \
         H5RS.c \
         H5S.c H5Sall.c H5Sdbg.c H5Shyper.c H5Smpio.c H5Snone.c H5Spoint.c \
-        H5Sselect.c H5Stest.c H5SL.c H5SM.c H5SMbtree2.c \
-        H5SMcache.c H5SMtest.c H5ST.c \
+        H5Sselect.c H5Stest.c \
+        H5SL.c \
+        H5SM.c H5SMbtree2.c H5SMcache.c H5SMmessage.c H5SMtest.c \
+        H5ST.c \
         H5T.c H5Tarray.c H5Tbit.c H5Tcommit.c H5Tcompound.c H5Tconv.c \
         H5Tcset.c H5Tdbg.c H5Tdeprec.c H5Tenum.c H5Tfields.c \
         H5Tfixed.c \
diff --git a/src/Makefile.in b/src/Makefile.in
index 768a86d..32f76c4 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -137,7 +137,7 @@ am_libhdf5_la_OBJECTS = H5.lo H5checksum.lo H5dbg.lo H5system.lo \
 	H5Pstrcpl.lo H5Ptest.lo H5R.lo H5Rdeprec.lo H5RC.lo H5RS.lo \
 	H5S.lo H5Sall.lo H5Sdbg.lo H5Shyper.lo H5Smpio.lo H5Snone.lo \
 	H5Spoint.lo H5Sselect.lo H5Stest.lo H5SL.lo H5SM.lo \
-	H5SMbtree2.lo H5SMcache.lo H5SMtest.lo H5ST.lo H5T.lo \
+	H5SMbtree2.lo H5SMcache.lo H5SMmessage.lo H5SMtest.lo H5ST.lo H5T.lo \
 	H5Tarray.lo H5Tbit.lo H5Tcommit.lo H5Tcompound.lo H5Tconv.lo \
 	H5Tcset.lo H5Tdbg.lo H5Tdeprec.lo H5Tenum.lo H5Tfields.lo \
 	H5Tfixed.lo H5Tfloat.lo H5Tinit.lo H5Tnative.lo H5Toffset.lo \
@@ -507,7 +507,7 @@ libhdf5_la_SOURCES = H5.c H5checksum.c H5dbg.c H5system.c H5timer.c H5trace.c \
         H5RS.c \
         H5S.c H5Sall.c H5Sdbg.c H5Shyper.c H5Smpio.c H5Snone.c H5Spoint.c \
         H5Sselect.c H5Stest.c H5SL.c H5SM.c H5SMbtree2.c \
-        H5SMcache.c H5SMtest.c H5ST.c \
+        H5SMcache.c H5SMmessage.c H5SMtest.c H5ST.c \
         H5T.c H5Tarray.c H5Tbit.c H5Tcommit.c H5Tcompound.c H5Tconv.c \
         H5Tcset.c H5Tdbg.c H5Tdeprec.c H5Tenum.c H5Tfields.c \
         H5Tfixed.c \
@@ -858,6 +858,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5SM.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5SMbtree2.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5SMcache.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5SMmessage.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5SMtest.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5ST.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/H5Sall.Plo@am__quote@