[svn-r25575] cleanup H5I usage in VOL by removing the use of the aux pointer and

make a higher level wrapper object around all VOL objects that
includes the VOL information.

1 files changed, 151 insertions, 256 deletions

diff --git a/src/H5A.c b/src/H5A.c
index 709a05f..2de57e5 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -93,8 +93,7 @@ static const H5I_class_t H5I_ATTR_CLS[1] = {{
     H5I_ATTR,                   /* ID class value */
     0,                          /* Class flags */
     0,                          /* # of reserved IDs for class */
-    NULL,                       /* Callback routine for closing objects of this class */
-    (H5I_free2_t)H5A_close_attr /* Callback routine for closing auxilary objects of this class */
+    (H5I_free_t)H5A_close_attr  /* Callback routine for closing objects of this class */
 }};
 
 
@@ -233,12 +232,11 @@ hid_t
 H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
     hid_t acpl_id, hid_t UNUSED aapl_id)
 {
-    void    *attr = NULL;       /* attr token from VOL plugin */
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
-    H5P_genplist_t      *plist;            /* Property list pointer */
+    void *attr = NULL;                /* attr token from VOL plugin */
+    H5VL_object_t *obj = NULL;        /* object token of loc_id */
+    H5P_genplist_t      *plist;       /* Property list pointer */
     H5VL_loc_params_t   loc_params;
-    hid_t		ret_value;              /* Return value */
+    hid_t		ret_value;    /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE6("i", "i*siiii", loc_id, attr_name, type_id, space_id, acpl_id, aapl_id);
@@ -266,25 +264,22 @@ H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the file object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid identifier")
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+    /* get the location object */
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin->cls, attr_name, acpl_id, aapl_id, 
-                                        H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_create(obj->vol_obj, loc_params, obj->vol_info->vol_cls, attr_name, 
+                                        acpl_id, aapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
-    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
+    /* Get an atom for the attribute */
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, obj->vol_info, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close(attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close(attr, obj->vol_info->vol_cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
 
     FUNC_LEAVE_API(ret_value)
@@ -327,12 +322,11 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     hid_t type_id, hid_t space_id, hid_t acpl_id, hid_t aapl_id,
     hid_t lapl_id)
 {
-    void    *attr = NULL;       /* attr token from VOL plugin */
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
-    H5P_genplist_t      *plist;            /* Property list pointer */
+    void *attr = NULL;                /* attr token from VOL plugin */
+    H5VL_object_t *obj = NULL;        /* object token of loc_id */
+    H5P_genplist_t      *plist;       /* Property list pointer */
     H5VL_loc_params_t    loc_params;
-    hid_t		 ret_value;        /* Return value */
+    hid_t		 ret_value;   /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE8("i", "i*s*siiiii", loc_id, obj_name, attr_name, type_id, space_id,
@@ -365,26 +359,22 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.loc_data.loc_by_name.name = obj_name;
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
 
-    /* get the file object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
-
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+    /* get the location object */
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin->cls, attr_name, acpl_id, 
-                                        aapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_create(obj->vol_obj, loc_params, obj->vol_info->vol_cls, attr_name, 
+                                        acpl_id, aapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
-    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the attribute */
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, obj->vol_info, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, obj->vol_info->vol_cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Acreate_by_name() */
@@ -412,11 +402,10 @@ done:
 hid_t
 H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
 {
-    void    *attr = NULL;       /* attr token from VOL plugin */
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
+    void *attr = NULL;                /* attr token from VOL plugin */
+    H5VL_object_t *obj = NULL;        /* object token of loc_id */
     H5VL_loc_params_t loc_params; 
-    hid_t		ret_value;
+    hid_t ret_value;
 
     FUNC_ENTER_API(FAIL)
     H5TRACE3("i", "i*si", loc_id, attr_name, aapl_id);
@@ -430,26 +419,22 @@ H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the file object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
-
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+    /* get the location object */
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
-    /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, attr_name, aapl_id, 
-                                      H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
+    /* Open the attribute through the VOL */
+    if(NULL == (attr = H5VL_attr_open(obj->vol_obj, loc_params, obj->vol_info->vol_cls, 
+                                      attr_name, aapl_id, H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the attribute */
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, obj->vol_info, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, obj->vol_info->vol_cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen() */
@@ -480,11 +465,10 @@ hid_t
 H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     hid_t aapl_id, hid_t lapl_id)
 {
-    void    *attr = NULL;       /* attr token from VOL plugin */
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
-    H5VL_loc_params_t   loc_params;
-    hid_t		ret_value;
+    void *attr = NULL;               /* attr token from VOL plugin */
+    H5VL_object_t *obj = NULL;       /* object token of loc_id */
+    H5VL_loc_params_t loc_params;
+    hid_t ret_value;
 
     FUNC_ENTER_API(FAIL)
     H5TRACE5("i", "i*s*sii", loc_id, obj_name, attr_name, aapl_id, lapl_id);
@@ -507,27 +491,24 @@ H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the file object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
+    /* get the location object */
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
-    /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, attr_name, aapl_id, 
-                                      H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
+    /* Open the attribute through the VOL */
+    if(NULL == (attr = H5VL_attr_open(obj->vol_obj, loc_params, obj->vol_info->vol_cls, 
+                                      attr_name, aapl_id, H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the attribute */
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, obj->vol_info, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, obj->vol_info->vol_cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
+
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_by_name() */
 
@@ -560,11 +541,10 @@ hid_t
 H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     H5_iter_order_t order, hsize_t n, hid_t aapl_id, hid_t lapl_id)
 {
-    void    *attr = NULL;       /* attr token from VOL plugin */
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
-    H5VL_loc_params_t   loc_params;
-    hid_t	ret_value;      /* Return value */
+    void *attr = NULL;                /* attr token from VOL plugin */
+    H5VL_object_t *obj = NULL;        /* object token of loc_id */
+    H5VL_loc_params_t loc_params;
+    hid_t ret_value;                  /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE7("i", "i*sIiIohii", loc_id, obj_name, idx_type, order, n, aapl_id,
@@ -593,26 +573,22 @@ H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.loc_data.loc_by_idx.lapl_id = lapl_id;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the file object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
+    /* get the location object */
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
-    /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, NULL, aapl_id, 
-                                      H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
+    /* Open the attribute through the VOL */
+    if(NULL == (attr = H5VL_attr_open(obj->vol_obj, loc_params, obj->vol_info->vol_cls, 
+                                      NULL, aapl_id, H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the attribute */
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, obj->vol_info, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, obj->vol_info->vol_cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_by_idx() */
@@ -637,25 +613,21 @@ done:
 herr_t
 H5Awrite(hid_t attr_id, hid_t dtype_id, const void *buf)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     herr_t ret_value;           /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE3("e", "ii*x", attr_id, dtype_id, buf);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
     if(NULL == buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "null attribute buffer")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     /* write the data through the VOL */
-    if((ret_value = H5VL_attr_write(attr, vol_plugin->cls, dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_write(attr->vol_obj, attr->vol_info->vol_cls, 
+                                    dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_READERROR, FAIL, "can't read data")
 
 done:
@@ -682,25 +654,21 @@ done:
 herr_t
 H5Aread(hid_t attr_id, hid_t dtype_id, void *buf)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     herr_t ret_value;           /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE3("e", "ii*x", attr_id, dtype_id, buf);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
     if(NULL == buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "null attribute buffer")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     /* Read the data through the VOL */
-    if((ret_value = H5VL_attr_read(attr, vol_plugin->cls, dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_read(attr->vol_obj, attr->vol_info->vol_cls, 
+                                   dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_READERROR, FAIL, "can't read data")
 
 done:
@@ -727,23 +695,19 @@ done:
 hid_t
 H5Aget_space(hid_t attr_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     hid_t	ret_value;
 
     FUNC_ENTER_API(FAIL)
     H5TRACE1("i", "i", attr_id);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     /* get the dataspace through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_SPACE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr->vol_obj, attr->vol_info->vol_cls, H5VL_ATTR_GET_SPACE, 
+                     H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get data space")
 
 done:
@@ -770,23 +734,19 @@ done:
 hid_t
 H5Aget_type(hid_t attr_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     hid_t	 ret_value;     /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE1("i", "i", attr_id);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     /* get the datatype through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_TYPE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr->vol_obj, attr->vol_info->vol_cls, H5VL_ATTR_GET_TYPE, 
+                     H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get type")
 
 done:
@@ -816,8 +776,7 @@ done:
 hid_t
 H5Aget_create_plist(hid_t attr_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     hid_t	ret_value;
 
     FUNC_ENTER_API(FAIL)
@@ -826,16 +785,12 @@ H5Aget_create_plist(hid_t attr_id)
     HDassert(H5P_LST_ATTRIBUTE_CREATE_ID_g != -1);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     /* get the acpl through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_ACPL, H5AC_dxpl_id, 
-                     H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr->vol_obj, attr->vol_info->vol_cls, H5VL_ATTR_GET_ACPL, 
+                     H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get acpl")
 
 done:
@@ -867,8 +822,7 @@ done:
 ssize_t
 H5Aget_name(hid_t attr_id, size_t buf_size, char *buf)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     H5VL_loc_params_t loc_params;
     ssize_t	ret_value;
 
@@ -876,7 +830,7 @@ H5Aget_name(hid_t attr_id, size_t buf_size, char *buf)
     H5TRACE3("Zs", "iz*s", attr_id, buf_size, buf);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
     if(!buf && buf_size)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid buffer")
@@ -884,12 +838,9 @@ H5Aget_name(hid_t attr_id, size_t buf_size, char *buf)
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = H5I_get_type(attr_id);
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     /* get the name through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_NAME, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(attr->vol_obj, attr->vol_info->vol_cls, H5VL_ATTR_GET_NAME, 
+                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                      loc_params, buf_size, buf, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 
@@ -920,8 +871,7 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     H5_iter_order_t order, hsize_t n, char *name /*out*/, size_t size,
     hid_t lapl_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t loc_params;
     ssize_t	ret_value;      /* Return value */
 
@@ -944,11 +894,8 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         if(TRUE != H5P_isa_class(lapl_id, H5P_LINK_ACCESS))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not link access property list ID")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     loc_params.type = H5VL_OBJECT_BY_IDX;
@@ -960,8 +907,8 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the name through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin->cls, H5VL_ATTR_GET_NAME, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
-                     loc_params, size, name, &ret_value) < 0)
+    if(H5VL_attr_get(obj->vol_obj, obj->vol_info->vol_cls, H5VL_ATTR_GET_NAME, 
+                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, loc_params, size, name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 
 done:
@@ -989,23 +936,19 @@ done:
 hsize_t
 H5Aget_storage_size(hid_t attr_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     hsize_t	ret_value;      /* Return value */
 
     FUNC_ENTER_API(0)
     H5TRACE1("h", "i", attr_id);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "not an attribute")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "ID does not contain VOL information")
-
     /* get the storage size through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_STORAGE_SIZE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr->vol_obj, attr->vol_info->vol_cls, H5VL_ATTR_GET_STORAGE_SIZE, 
+                     H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, 0, "unable to get acpl")
 
 done:
@@ -1029,8 +972,7 @@ done:
 herr_t
 H5Aget_info(hid_t attr_id, H5A_info_t *ainfo)
 {
-    H5VL_t     *vol_plugin;
-    void       *attr;
+    H5VL_object_t *attr;
     H5VL_loc_params_t loc_params;
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -1038,19 +980,15 @@ H5Aget_info(hid_t attr_id, H5A_info_t *ainfo)
     H5TRACE2("e", "i*x", attr_id, ainfo);
 
     /* check arguments */
-    if(NULL == (attr = (void *)H5I_object_verify(attr_id, H5I_ATTR)))
+    if(NULL == (attr = (H5VL_object_t *)H5I_object_verify(attr_id, H5I_ATTR)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an attribute")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(attr_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
-
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = H5I_get_type(attr_id);
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, 
-                     H5_REQUEST_NULL, loc_params, ainfo) < 0)
+    if(H5VL_attr_get(attr->vol_obj, attr->vol_info->vol_cls, H5VL_ATTR_GET_INFO, 
+                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, loc_params, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 done:
@@ -1075,8 +1013,7 @@ herr_t
 H5Aget_info_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     H5A_info_t *ainfo, hid_t lapl_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t   loc_params;
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -1103,16 +1040,13 @@ H5Aget_info_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin->cls, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
-                     loc_params, ainfo, attr_name) < 0)
+    if(H5VL_attr_get(obj->vol_obj, obj->vol_info->vol_cls, H5VL_ATTR_GET_INFO, 
+                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, loc_params, ainfo, attr_name) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 done:
@@ -1138,8 +1072,7 @@ herr_t
 H5Aget_info_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     H5_iter_order_t order, hsize_t n, H5A_info_t *ainfo, hid_t lapl_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t   loc_params;
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -1172,16 +1105,13 @@ H5Aget_info_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.loc_data.loc_by_idx.lapl_id = lapl_id;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin->cls, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
-                     loc_params, ainfo) < 0)
+    if(H5VL_attr_get(obj->vol_obj, obj->vol_info->vol_cls, H5VL_ATTR_GET_INFO, 
+                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, loc_params, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
 done:
@@ -1218,22 +1148,18 @@ H5Arename(hid_t loc_id, const char *old_name, const char *new_name)
 
     /* Avoid thrashing things if the names are the same */
     if(HDstrcmp(old_name, new_name)) {
-        H5VL_t     *vol_plugin;
-        void       *obj;
+        H5VL_object_t *obj;
         H5VL_loc_params_t loc_params;
 
         loc_params.type = H5VL_OBJECT_BY_SELF;
         loc_params.obj_type = H5I_get_type(loc_id);
 
-        /* get the file object */
-        if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
-        /* get the plugin pointer */
-        if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+        /* get the location object */
+        if(NULL == (obj = H5VL_get_object(loc_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
         /* rename the attribute info through the VOL */
-        if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_RENAME,
+        if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_RENAME,
                                            H5AC_dxpl_id, H5_REQUEST_NULL, old_name, new_name)) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTRENAME, FAIL, "can't rename attribute")
     }
@@ -1282,8 +1208,7 @@ H5Arename_by_name(hid_t loc_id, const char *obj_name, const char *old_attr_name,
 
     /* Avoid thrashing things if the names are the same */
     if(HDstrcmp(old_attr_name, new_attr_name)) {
-        H5VL_t     *vol_plugin;
-        void       *obj;
+        H5VL_object_t *obj;
         H5VL_loc_params_t loc_params;
 
         loc_params.type = H5VL_OBJECT_BY_NAME;
@@ -1291,17 +1216,13 @@ H5Arename_by_name(hid_t loc_id, const char *obj_name, const char *old_attr_name,
         loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
         loc_params.obj_type = H5I_get_type(loc_id);
 
-        /* get the file object */
-        if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
-        /* get the plugin pointer */
-        if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+        /* get the location object */
+        if(NULL == (obj = H5VL_get_object(loc_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
         /* rename the attribute info through the VOL */
-        if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_RENAME,
-                                           H5AC_dxpl_id, H5_REQUEST_NULL, 
-                                           old_attr_name, new_attr_name)) < 0)
+        if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_RENAME,
+                                           H5AC_dxpl_id, H5_REQUEST_NULL, old_attr_name, new_attr_name)) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTRENAME, FAIL, "can't rename attribute")
     } /* end if */
 
@@ -1355,8 +1276,7 @@ herr_t
 H5Aiterate2(hid_t loc_id, H5_index_t idx_type, H5_iter_order_t order,
     hsize_t *idx, H5A_operator2_t op, void *op_data)
 {
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
+    H5VL_object_t *obj = NULL;        /* object token of loc_id */
     H5VL_loc_params_t loc_params;
     herr_t	ret_value;      /* Return value */
 
@@ -1375,14 +1295,11 @@ H5Aiterate2(hid_t loc_id, H5_index_t idx_type, H5_iter_order_t order,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the loc object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_ITER,
+    if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_ITER,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, 
                                        idx_type, order, idx, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "attribute iteration failed")
@@ -1440,8 +1357,7 @@ H5Aiterate_by_name(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     H5_iter_order_t order, hsize_t *idx, H5A_operator2_t op, void *op_data,
     hid_t lapl_id)
 {
-    void    *obj = NULL;        /* object token of loc_id */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
+    H5VL_object_t *obj = NULL;        /* object token of loc_id */
     H5VL_loc_params_t loc_params;
     herr_t   ret_value = SUCCEED;      /* Return value */
 
@@ -1470,14 +1386,11 @@ H5Aiterate_by_name(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
 
     /* get the loc object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
+    if(NULL == (obj = H5VL_get_object(loc_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_ITER,
+    if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_ITER,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, 
                                        idx_type, order, idx, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "attribute iteration failed")
@@ -1504,8 +1417,7 @@ done:
 herr_t
 H5Adelete(hid_t loc_id, const char *name)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t loc_params;
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -1521,15 +1433,12 @@ H5Adelete(hid_t loc_id, const char *name)
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_DELETE,
+    if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_DELETE,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, name)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
@@ -1558,8 +1467,7 @@ herr_t
 H5Adelete_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     hid_t lapl_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t loc_params;
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -1584,15 +1492,12 @@ H5Adelete_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_DELETE,
+    if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_DELETE,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, attr_name)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
@@ -1629,8 +1534,7 @@ herr_t
 H5Adelete_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     H5_iter_order_t order, hsize_t n, hid_t lapl_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t loc_params;
     herr_t	ret_value = SUCCEED;    /* Return value */
 
@@ -1660,15 +1564,12 @@ H5Adelete_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.loc_data.loc_by_idx.lapl_id = lapl_id;
     loc_params.obj_type = H5I_get_type(loc_id);
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_DELETE,
+    if((ret_value = H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_DELETE,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
@@ -1730,8 +1631,7 @@ done:
 htri_t
 H5Aexists(hid_t obj_id, const char *attr_name)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t loc_params;
     htri_t	ret_value;              /* Return value */
 
@@ -1744,18 +1644,15 @@ H5Aexists(hid_t obj_id, const char *attr_name)
     if(!attr_name || !*attr_name)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no attribute name")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(obj_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(obj_id)))
+    if(NULL == (obj = H5VL_get_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     loc_params.type = H5VL_OBJECT_BY_SELF;
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* Check existence of attribute through the VOL */
-    if(H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_EXISTS,
+    if(H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_EXISTS,
                           H5AC_ind_dxpl_id, H5_REQUEST_NULL, attr_name, &ret_value) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to determine if attribute exists")
 done:
@@ -1780,8 +1677,7 @@ htri_t
 H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     hid_t lapl_id)
 {
-    H5VL_t     *vol_plugin;
-    void       *obj;
+    H5VL_object_t *obj;
     H5VL_loc_params_t loc_params;
     htri_t	ret_value;              /* Return value */
 
@@ -1801,11 +1697,8 @@ H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         if(TRUE != H5P_isa_class(lapl_id, H5P_LINK_ACCESS))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not link access property list ID")
 
-    /* get the plugin pointer */
-    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
     /* get the object */
-    if(NULL == (obj = (void *)H5VL_get_object(loc_id)))
+    if(NULL == (obj = H5VL_get_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     loc_params.type = H5VL_OBJECT_BY_NAME;
@@ -1814,7 +1707,7 @@ H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* Check existence of attribute through the VOL */
-    if(H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_EXISTS,
+    if(H5VL_attr_specific(obj->vol_obj, loc_params, obj->vol_info->vol_cls, H5VL_ATTR_EXISTS,
                           H5AC_ind_dxpl_id, H5_REQUEST_NULL, attr_name, &ret_value) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to determine if attribute exists")
 
@@ -1838,19 +1731,21 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5A_close_attr(void *attr, H5VL_t *vol_plugin)
+H5A_close_attr(void *_attr)
 {
-    herr_t              ret_value = SUCCEED;    /* Return value */
+    H5VL_object_t *attr = (H5VL_object_t *)_attr;
+    herr_t ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the attr through the VOL*/
-    if((ret_value = H5VL_attr_close(attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_close(attr->vol_obj, attr->vol_info->vol_cls, 
+                                    H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to close attribute")
 
-    /* decrement ref count on VOL ID */
-    if(H5VL_free_id(vol_plugin) < 0)
-	HGOTO_ERROR(H5E_ATTR, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+    /* free attribute */
+    if(H5VL_free_object(attr) < 0)
+        HGOTO_ERROR(H5E_ATTR, H5E_CANTDEC, FAIL, "unable to free VOL object")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)