Merge branch 'develop' of https://bitbucket.hdfgroup.org/scm/~bmribler/hdf5_bmr_fixbug into develop

32 files changed, 1053 insertions, 722 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 40b64f5..ff7402b 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -943,6 +943,21 @@ if (BUILD_SHARED_LIBS)
   file (MAKE_DIRECTORY "${HDF5_BINARY_DIR}/shared")
 endif ()
 
+if (LOCAL_BATCH_TEST)
+  if (LOCAL_BATCH_SCRIPT_NAME)
+    configure_file (
+        ${HDF5_SOURCE_DIR}/bin/batch/${LOCAL_BATCH_SCRIPT_NAME}.in.cmake
+        ${HDF5_BINARY_DIR}/${LOCAL_BATCH_SCRIPT_NAME} ESCAPE_QUOTES @ONLY
+    )
+  endif ()
+  if (LOCAL_BATCH_SCRIPT_PARALLEL_NAME)
+    configure_file (
+        ${HDF5_SOURCE_DIR}/bin/batch/${LOCAL_BATCH_SCRIPT_PARALLEL_NAME}.in.cmake
+        ${HDF5_BINARY_DIR}/${LOCAL_BATCH_SCRIPT_PARALLEL_NAME} ESCAPE_QUOTES @ONLY
+    )
+  endif ()
+endif ()
+
 if (NOT EXISTS ${HDF5_GENERATED_SOURCE_DIR}/H5Tinit.c)
   add_executable (H5detect ${HDF5_SRC_DIR}/H5detect.c)
   target_include_directories(H5detect PRIVATE "${HDF5_SRC_DIR};${HDF5_BINARY_DIR};$<$<BOOL:${HDF5_ENABLE_PARALLEL}>:${MPI_C_INCLUDE_DIRS}>")
diff --git a/src/H5A.c b/src/H5A.c
index 1b804d9..9c3ad7e 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -951,6 +951,8 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "location is not valid for an attribute")
     if(!obj_name || !*obj_name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no name")
+    if(!name && size)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "name cannot be NULL if size is non-zero")
     if(idx_type <= H5_INDEX_UNKNOWN || idx_type >= H5_INDEX_N)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid index type specified")
     if(order <= H5_ITER_UNKNOWN || order >= H5_ITER_N)
diff --git a/src/H5CX.c b/src/H5CX.c
index 1d9cf3d..0d20132 100644
--- a/src/H5CX.c
+++ b/src/H5CX.c
@@ -198,6 +198,7 @@ typedef struct H5CX_t {
     MPI_Datatype btype;         /* MPI datatype for buffer, when using collective I/O */
     MPI_Datatype ftype;         /* MPI datatype for file, when using collective I/O */
     hbool_t mpi_file_flushing;  /* Whether an MPI-opened file is being flushed */
+    hbool_t rank0_bcast;        /* Whether a dataset meets read-with-rank0-and-bcast requirements */
 #endif /* H5_HAVE_PARALLEL */
 
     /* Cached DXPL properties */
@@ -261,6 +262,8 @@ typedef struct H5CX_t {
     hbool_t mpio_coll_chunk_multi_ratio_coll_set; /* Whether instrumented "collective chunk multi ratio coll" value is set */
     int mpio_coll_chunk_multi_ratio_ind;  /* Instrumented "collective chunk multi ratio ind" value (H5D_XFER_COLL_CHUNK_MULTI_RATIO_IND_NAME) */
     hbool_t mpio_coll_chunk_multi_ratio_ind_set; /* Whether instrumented "collective chunk multi ratio ind" value is set */
+    hbool_t mpio_coll_rank0_bcast;  /* Instrumented "collective chunk multi ratio ind" value (H5D_XFER_COLL_CHUNK_MULTI_RATIO_IND_NAME) */
+    hbool_t mpio_coll_rank0_bcast_set; /* Whether instrumented "collective chunk multi ratio ind" value is set */
 #endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
 #endif /* H5_HAVE_PARALLEL */
 
@@ -268,9 +271,11 @@ typedef struct H5CX_t {
     size_t nlinks;              /* Number of soft / UD links to traverse (H5L_ACS_NLINKS_NAME) */
     hbool_t nlinks_valid;       /* Whether number of soft / UD links to traverse is valid */
 
-    /* Cached VOL properties */
-    void *vol_wrap_ctx;         /* VOL plugin's "wrap context" for creating IDs */
-    hbool_t vol_wrap_ctx_valid; /* Whether VOL plugin's "wrap context" for creating IDs is valid */
+    /* Cached VOL settings */
+    H5VL_connector_prop_t vol_connector_prop;  /* Property for VOL connector ID & info */
+    hbool_t vol_connector_prop_valid; /* Whether property for VOL connector ID & info is valid */
+    void *vol_wrap_ctx;         /* VOL connector's "wrap context" for creating IDs */
+    hbool_t vol_wrap_ctx_valid; /* Whether VOL connector's "wrap context" for creating IDs is valid */
 } H5CX_t;
 
 /* Typedef for nodes on the API context stack */
@@ -956,6 +961,40 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5CX_set_vol_connector_prop
+ *
+ * Purpose:     Sets the VOL connector ID & info for an operation.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              January 3, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_set_vol_connector_prop(const H5VL_connector_prop_t *vol_connector_prop)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(head && *head);
+
+    /* Set the API context value */
+    HDmemcpy(&(*head)->ctx.vol_connector_prop, vol_connector_prop, sizeof(H5VL_connector_prop_t));
+
+    /* Mark the value as valid */
+    (*head)->ctx.vol_connector_prop_valid = TRUE;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_set_vol_connector_prop() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5CX_get_dxpl
  *
  * Purpose:     Retrieves the DXPL ID for the current API call context.
@@ -1044,6 +1083,42 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5CX_get_vol_connector_prop
+ *
+ * Purpose:     Retrieves the VOL connector ID & info for an operation.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              January 3, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_vol_connector_prop(H5VL_connector_prop_t *vol_connector_prop)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(vol_connector_prop);
+    HDassert(head && *head);
+
+    /* Check for value that was set */
+    if((*head)->ctx.vol_connector_prop_valid)
+        /* Get the value */
+        HDmemcpy(vol_connector_prop, &(*head)->ctx.vol_connector_prop, sizeof(H5VL_connector_prop_t));
+    else
+        HDmemset(vol_connector_prop, 0, sizeof(H5VL_connector_prop_t));
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_get_vol_connector_prop() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5CX_get_tag
  *
  * Purpose:     Retrieves the object tag for the current API call context.
@@ -1182,6 +1257,32 @@ H5CX_get_mpi_file_flushing(void)
 
     FUNC_LEAVE_NOAPI((*head)->ctx.mpi_file_flushing)
 } /* end H5CX_get_mpi_file_flushing() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_get_mpio_rank0_bcast 
+ *
+ * Purpose:     Retrieves if the dataset meets read-with-rank0-and-bcast requirements for the current API call context.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  M. Breitenfeld
+ *              December 31, 2018
+ *
+ *-------------------------------------------------------------------------
+ */
+hbool_t
+H5CX_get_mpio_rank0_bcast(void)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Sanity check */
+    HDassert(head && *head);
+
+    FUNC_LEAVE_NOAPI((*head)->ctx.rank0_bcast)
+} /* end H5CX_get_mpio_rank0_bcast() */
 #endif /* H5_HAVE_PARALLEL */
 
 
@@ -2113,6 +2214,34 @@ H5CX_set_mpi_file_flushing(hbool_t flushing)
 
     FUNC_LEAVE_NOAPI_VOID
 } /* end H5CX_set_mpi_file_flushing() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_set_mpio_rank0_bcast
+ *
+ * Purpose:     Sets the "dataset meets read-with-rank0-and-bcast requirements" flag for the current API call context.
+ *
+ * Return:      <none>
+ *
+ * Programmer:  M. Breitenfeld
+ *              December 31, 2018
+ *
+ *-------------------------------------------------------------------------
+ */
+void
+H5CX_set_mpio_rank0_bcast(hbool_t rank0_bcast)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Sanity checks */
+    HDassert(head && *head);
+
+    (*head)->ctx.rank0_bcast = rank0_bcast;
+
+    FUNC_LEAVE_NOAPI_VOID
+} /* end H5CX_set_mpio_rank0_bcast() */
 #endif /* H5_HAVE_PARALLEL */
 
 
@@ -2524,6 +2653,40 @@ H5CX_test_set_mpio_coll_chunk_multi_ratio_ind(int mpio_coll_chunk_multi_ratio_in
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5CX_test_set_mpio_coll_chunk_multi_ratio_ind() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_test_set_mpio_coll_rank0_bcast
+ *
+ * Purpose:     Sets the instrumented "read-with-rank0-bcast" flag for the current API call context.
+ *
+ * Note:        Only sets value if property set in DXPL
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              January 2, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_test_set_mpio_coll_rank0_bcast(hbool_t mpio_coll_rank0_bcast)
+{
+    H5CX_node_t **head = H5CX_get_my_context();  /* Get the pointer to the head of the API context, for this thread */
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    /* Sanity checks */
+    HDassert(head && *head);
+    HDassert(!((*head)->ctx.dxpl_id == H5P_DEFAULT || 
+            (*head)->ctx.dxpl_id == H5P_DATASET_XFER_DEFAULT));
+
+    H5CX_TEST_SET_PROP(H5D_XFER_COLL_RANK0_BCAST_NAME, mpio_coll_rank0_bcast)
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_test_set_mpio_coll_rank0_bcast() */
 #endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
 #endif /* H5_HAVE_PARALLEL */
 
@@ -2568,6 +2731,7 @@ H5CX__pop_common(void)
     H5CX_SET_PROP(H5D_XFER_COLL_CHUNK_LINK_NUM_FALSE_NAME, mpio_coll_chunk_link_num_false)
     H5CX_SET_PROP(H5D_XFER_COLL_CHUNK_MULTI_RATIO_COLL_NAME, mpio_coll_chunk_multi_ratio_coll)
     H5CX_SET_PROP(H5D_XFER_COLL_CHUNK_MULTI_RATIO_IND_NAME, mpio_coll_chunk_multi_ratio_ind)
+    H5CX_SET_PROP(H5D_XFER_COLL_RANK0_BCAST_NAME, mpio_coll_rank0_bcast)
 #endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
 #endif /* H5_HAVE_PARALLEL */
 
diff --git a/src/H5CXprivate.h b/src/H5CXprivate.h
index 57ca5cd..46d25d0 100644
--- a/src/H5CXprivate.h
+++ b/src/H5CXprivate.h
@@ -64,17 +64,20 @@ H5_DLL herr_t H5CX_set_apl(hid_t *acspl_id, const H5P_libclass_t *libclass,
     hid_t loc_id, hbool_t is_collective);
 H5_DLL herr_t H5CX_set_loc(hid_t loc_id);
 H5_DLL herr_t H5CX_set_vol_wrap_ctx(void *wrap_ctx);
+H5_DLL herr_t H5CX_set_vol_connector_prop(const H5VL_connector_prop_t *vol_connector_prop);
 
 /* "Getter" routines for API context info */
 H5_DLL hid_t H5CX_get_dxpl(void);
 H5_DLL hid_t H5CX_get_lapl(void);
 H5_DLL herr_t H5CX_get_vol_wrap_ctx(void **wrap_ctx);
+H5_DLL herr_t H5CX_get_vol_connector_prop(H5VL_connector_prop_t *vol_connector_prop);
 H5_DLL haddr_t H5CX_get_tag(void);
 H5_DLL H5AC_ring_t H5CX_get_ring(void);
 #ifdef H5_HAVE_PARALLEL
 H5_DLL hbool_t H5CX_get_coll_metadata_read(void);
 H5_DLL herr_t H5CX_get_mpi_coll_datatypes(MPI_Datatype *btype, MPI_Datatype *ftype);
 H5_DLL hbool_t H5CX_get_mpi_file_flushing(void);
+H5_DLL hbool_t H5CX_get_mpio_rank0_bcast(void);
 #endif /* H5_HAVE_PARALLEL */
 
 /* "Getter" routines for DXPL properties cached in API context */
@@ -110,6 +113,7 @@ H5_DLL void H5CX_set_coll_metadata_read(hbool_t cmdr);
 H5_DLL herr_t H5CX_set_mpi_coll_datatypes(MPI_Datatype btype, MPI_Datatype ftype);
 H5_DLL herr_t H5CX_set_mpio_coll_opt(H5FD_mpio_collective_opt_t mpio_coll_opt);
 H5_DLL void H5CX_set_mpi_file_flushing(hbool_t flushing);
+H5_DLL void H5CX_set_mpio_rank0_bcast(hbool_t rank0_bcast);
 #endif /* H5_HAVE_PARALLEL */
 
 /* "Setter" routines for DXPL properties cached in API context */
@@ -135,6 +139,7 @@ H5_DLL herr_t H5CX_test_set_mpio_coll_chunk_link_num_true(int mpio_coll_chunk_li
 H5_DLL herr_t H5CX_test_set_mpio_coll_chunk_link_num_false(int mpio_coll_chunk_link_num_false);
 H5_DLL herr_t H5CX_test_set_mpio_coll_chunk_multi_ratio_coll(int mpio_coll_chunk_multi_ratio_coll);
 H5_DLL herr_t H5CX_test_set_mpio_coll_chunk_multi_ratio_ind(int mpio_coll_chunk_multi_ratio_ind);
+H5_DLL herr_t H5CX_test_set_mpio_coll_rank0_bcast(hbool_t rank0_bcast);
 #endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
 #endif /* H5_HAVE_PARALLEL */
 
diff --git a/src/H5Dchunk.c b/src/H5Dchunk.c
index b5a5c39..e165569 100644
--- a/src/H5Dchunk.c
+++ b/src/H5Dchunk.c
@@ -1998,13 +1998,13 @@ H5D__chunk_mem_cb(void H5_ATTR_UNUSED *elem, const H5T_t H5_ATTR_UNUSED *type, u
          */
         /* Get the chunk node from the skip list */
         if(NULL == (chunk_info = (H5D_chunk_info_t *)H5SL_search(fm->sel_chunks, &chunk_index)))
-            HGOTO_ERROR(H5E_DATASPACE, H5E_NOTFOUND, FAIL, "can't locate chunk in skip list")
+            HGOTO_ERROR(H5E_DATASPACE, H5E_NOTFOUND, H5_ITER_ERROR, "can't locate chunk in skip list")
 
         /* Check if the chunk already has a memory space */
         if(NULL == chunk_info->mspace) {
             /* Copy the template memory chunk dataspace */
             if(NULL == (chunk_info->mspace = H5S_copy(fm->mchunk_tmpl, FALSE, FALSE)))
-                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "unable to copy file space")
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, H5_ITER_ERROR, "unable to copy file space")
         } /* end else */
 
         /* Update the "last chunk seen" information */
@@ -2014,21 +2014,21 @@ H5D__chunk_mem_cb(void H5_ATTR_UNUSED *elem, const H5T_t H5_ATTR_UNUSED *type, u
 
     /* Get coordinates of selection iterator for memory */
     if(H5S_SELECT_ITER_COORDS(&fm->mem_iter, coords_in_mem) < 0)
-        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, FAIL, "unable to get iterator coordinates")
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTGET, H5_ITER_ERROR, "unable to get iterator coordinates")
 
     /* Add point to memory selection for chunk */
     if(fm->msel_type == H5S_SEL_POINTS) {
         if(H5S_select_elements(chunk_info->mspace, H5S_SELECT_APPEND, (size_t)1, coords_in_mem) < 0)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, FAIL, "unable to select element")
+            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, H5_ITER_ERROR, "unable to select element")
     } /* end if */
     else {
         if(H5S_hyper_add_span_element(chunk_info->mspace, fm->m_ndims, coords_in_mem) < 0)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, FAIL, "unable to select element")
+            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, H5_ITER_ERROR, "unable to select element")
     } /* end else */
 
     /* Move memory selection iterator to next element in selection */
     if(H5S_SELECT_ITER_NEXT(&fm->mem_iter, (size_t)1) < 0)
-        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTNEXT, FAIL, "unable to move to next iterator location")
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTNEXT, H5_ITER_ERROR, "unable to move to next iterator location")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
diff --git a/src/H5Dio.c b/src/H5Dio.c
index fe85d23..607bfcf 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -657,22 +657,12 @@ H5D__write(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
 
     /* Various MPI based checks */
 #ifdef H5_HAVE_PARALLEL
-    if H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI) {
-        /* If MPI based VFD is used, no VL datatype support yet. */
+    if(H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI)) {
+        /* If MPI based VFD is used, no VL or region reference datatype support yet. */
         /* This is because they use the global heap in the file and we don't */
         /* support parallel access of that yet */
-        if(H5T_detect_class(type_info.mem_type, H5T_VLEN, FALSE) > 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing VL datatypes yet")
-
-        /* If MPI based VFD is used, no VL datatype support yet. */
-        /* This is because they use the global heap in the file and we don't */
-        /* support parallel access of that yet */
-        /* We should really use H5T_detect_class() here, but it will be difficult
-         * to detect the type of the reference if it is nested... -QAK
-         */
-        if(H5T_get_class(type_info.mem_type, TRUE) == H5T_REFERENCE &&
-                H5T_get_ref_type(type_info.mem_type) == H5R_DATASET_REGION)
-            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing region reference datatypes yet")
+        if(H5T_is_vl_storage(type_info.mem_type) > 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing VL or region reference datatypes yet")
     } /* end if */
     else {
         H5FD_mpio_xfer_t io_xfer_mode;      /* MPI I/O transfer mode */
@@ -1153,15 +1143,19 @@ H5D__ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset,
                 hbool_t                         local_error_message_previously_written = FALSE;
                 hbool_t                         global_error_message_previously_written = FALSE;
                 size_t                          index;
-                char                            local_no_collective_cause_string[256] = "";
-                char                            global_no_collective_cause_string[256] = "";
+                size_t                          cause_strings_len;
+                char                            local_no_collective_cause_string[512] = "";
+                char                            global_no_collective_cause_string[512] = "";
                 const char                     *cause_strings[] = { "independent I/O was requested",
                                                                     "datatype conversions were required",
                                                                     "data transforms needed to be applied",
                                                                     "optimized MPI types flag wasn't set",
                                                                     "one of the dataspaces was neither simple nor scalar",
                                                                     "dataset was not contiguous or chunked",
-                                                                    "parallel writes to filtered datasets are disabled" };
+                                                                    "parallel writes to filtered datasets are disabled",
+                                                                    "an error occurred while checking if collective I/O was possible" };
+
+                cause_strings_len = sizeof(cause_strings) / sizeof(cause_strings[0]);
 
                 if(H5CX_get_mpio_local_no_coll_cause(&local_no_collective_cause) < 0)
                     HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to get local no collective cause value")
@@ -1170,7 +1164,7 @@ H5D__ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset,
 
                 /* Append each of the "reason for breaking collective I/O" error messages to the
                  * local and global no collective cause strings */
-                for (cause = 1, index = 0; cause < H5D_MPIO_NO_COLLECTIVE_MAX_CAUSE; cause <<= 1, index++) {
+                for (cause = 1, index = 0; (cause < H5D_MPIO_NO_COLLECTIVE_MAX_CAUSE) && (index < cause_strings_len); cause <<= 1, index++) {
                     size_t cause_strlen = HDstrlen(cause_strings[index]);
 
                     if (cause & local_no_collective_cause) {
diff --git a/src/H5Dmpio.c b/src/H5Dmpio.c
index 2c06800..f5da33d 100644
--- a/src/H5Dmpio.c
+++ b/src/H5Dmpio.c
@@ -37,7 +37,6 @@
 #include "H5Eprivate.h"       /* Error handling    */
 #include "H5Fprivate.h"       /* File access       */
 #include "H5FDprivate.h"      /* File drivers      */
-#include "H5FDmpi.h"          /* MPI-based file drivers	*/
 #include "H5Iprivate.h"       /* IDs               */
 #include "H5MMprivate.h"      /* Memory management */
 #include "H5Oprivate.h"       /* Object headers    */
@@ -89,10 +88,20 @@
 /******************/
 /* Combine chunk address and chunk info into a struct for better performance. */
 typedef struct H5D_chunk_addr_info_t {
-  haddr_t chunk_addr;
-  H5D_chunk_info_t chunk_info;
+    haddr_t chunk_addr;
+    H5D_chunk_info_t chunk_info;
 } H5D_chunk_addr_info_t;
 
+/* Rank 0 Bcast values */
+typedef enum H5D_mpio_no_rank0_bcast_cause_t {
+    H5D_MPIO_RANK0_BCAST = 0x00,
+    H5D_MPIO_RANK0_NOT_H5S_ALL = 0x01,
+    H5D_MPIO_RANK0_NOT_CONTIGUOUS = 0x02,
+    H5D_MPIO_RANK0_NOT_FIXED_SIZE = 0x04,
+    H5D_MPIO_RANK0_GREATER_THAN_2GB = 0x08
+} H5D_mpio_no_rank0_bcast_cause_t;
+
+
 /*
  * Information about a single chunk when performing collective filtered I/O. All
  * of the fields of one of these structs are initialized at the start of collective
@@ -281,8 +290,10 @@ H5D__mpio_opt_possible(const H5D_io_info_t *io_info, const H5S_t *file_space,
     const H5S_t *mem_space, const H5D_type_info_t *type_info)
 {
     H5FD_mpio_xfer_t io_xfer_mode;      /* MPI I/O transfer mode */
-    unsigned local_cause = 0;                /* Local reason(s) for breaking collective mode */
-    unsigned global_cause = 0;               /* Global reason(s) for breaking collective mode */
+    unsigned local_cause[2] = {0,0};    /* [0] Local reason(s) for breaking collective mode */
+                                        /* [1] Flag if dataset is both: H5S_ALL and small */
+    unsigned global_cause[2] = {0,0};   /* Global reason(s) for breaking collective mode */
+    htri_t is_vl_storage;               /* Whether the dataset's datatype is stored in a variable-length form */
     htri_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_PACKAGE
@@ -296,36 +307,37 @@ H5D__mpio_opt_possible(const H5D_io_info_t *io_info, const H5S_t *file_space,
 
     /* For independent I/O, get out quickly and don't try to form consensus */
     if(H5CX_get_io_xfer_mode(&io_xfer_mode) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get MPI-I/O transfer mode")
+        /* Set error flag, but keep going */
+        local_cause[0] |= H5D_MPIO_ERROR_WHILE_CHECKING_COLLECTIVE_POSSIBLE;
     if(io_xfer_mode == H5FD_MPIO_INDEPENDENT)
-        local_cause |= H5D_MPIO_SET_INDEPENDENT;
+        local_cause[0] |= H5D_MPIO_SET_INDEPENDENT;
 
     /* Optimized MPI types flag must be set */
     /* (based on 'HDF5_MPI_OPT_TYPES' environment variable) */
     if(!H5FD_mpi_opt_types_g)
-        local_cause |= H5D_MPIO_MPI_OPT_TYPES_ENV_VAR_DISABLED;
+        local_cause[0] |= H5D_MPIO_MPI_OPT_TYPES_ENV_VAR_DISABLED;
 
     /* Don't allow collective operations if datatype conversions need to happen */
     if(!type_info->is_conv_noop)
-        local_cause |= H5D_MPIO_DATATYPE_CONVERSION;
+        local_cause[0] |= H5D_MPIO_DATATYPE_CONVERSION;
 
     /* Don't allow collective operations if data transform operations should occur */
     if(!type_info->is_xform_noop)
-        local_cause |= H5D_MPIO_DATA_TRANSFORMS;
+        local_cause[0] |= H5D_MPIO_DATA_TRANSFORMS;
 
     /* Check whether these are both simple or scalar dataspaces */
     if(!((H5S_SIMPLE == H5S_GET_EXTENT_TYPE(mem_space) || H5S_SCALAR == H5S_GET_EXTENT_TYPE(mem_space))
             && (H5S_SIMPLE == H5S_GET_EXTENT_TYPE(file_space) || H5S_SCALAR == H5S_GET_EXTENT_TYPE(file_space))))
-        local_cause |= H5D_MPIO_NOT_SIMPLE_OR_SCALAR_DATASPACES;
+        local_cause[0] |= H5D_MPIO_NOT_SIMPLE_OR_SCALAR_DATASPACES;
 
     /* Dataset storage must be contiguous or chunked */
     if(!(io_info->dset->shared->layout.type == H5D_CONTIGUOUS ||
             io_info->dset->shared->layout.type == H5D_CHUNKED))
-        local_cause |= H5D_MPIO_NOT_CONTIGUOUS_OR_CHUNKED_DATASET;
+        local_cause[0] |= H5D_MPIO_NOT_CONTIGUOUS_OR_CHUNKED_DATASET;
 
     /* check if external-file storage is used */
     if(io_info->dset->shared->dcpl_cache.efl.nused > 0)
-        local_cause |= H5D_MPIO_NOT_CONTIGUOUS_OR_CHUNKED_DATASET;
+        local_cause[0] |= H5D_MPIO_NOT_CONTIGUOUS_OR_CHUNKED_DATASET;
 
     /* The handling of memory space is different for chunking and contiguous
      *  storage.  For contiguous storage, mem_space and file_space won't change
@@ -340,31 +352,84 @@ H5D__mpio_opt_possible(const H5D_io_info_t *io_info, const H5S_t *file_space,
      * is less than 3. The functions needed (MPI_Mprobe and MPI_Imrecv) will
      * not be available.
      */
-    if (io_info->op_type == H5D_IO_OP_WRITE &&
-        io_info->dset->shared->layout.type == H5D_CHUNKED &&
-        io_info->dset->shared->dcpl_cache.pline.nused > 0)
-        local_cause |= H5D_MPIO_PARALLEL_FILTERED_WRITES_DISABLED;
+    if(io_info->op_type == H5D_IO_OP_WRITE &&
+            io_info->dset->shared->layout.type == H5D_CHUNKED &&
+            io_info->dset->shared->dcpl_cache.pline.nused > 0)
+        local_cause[0] |= H5D_MPIO_PARALLEL_FILTERED_WRITES_DISABLED;
 #endif
 
+    /* Check if we are able to do a MPI_Bcast of the data from one rank
+     * instead of having all the processes involved in the collective I/O call.
+     */
+
+    /* Check to see if the process is reading the entire dataset */
+    if(H5S_GET_SELECT_TYPE(file_space) != H5S_SEL_ALL)
+        local_cause[1] |= H5D_MPIO_RANK0_NOT_H5S_ALL; 
+    /* Only perform this optimization for contigous datasets, currently */
+    else if(H5D_CONTIGUOUS != io_info->dset->shared->layout.type)
+        /* Flag to do a MPI_Bcast of the data from one proc instead of 
+         * having all the processes involved in the collective I/O.
+         */
+        local_cause[1] |= H5D_MPIO_RANK0_NOT_CONTIGUOUS; 
+    else if((is_vl_storage = H5T_is_vl_storage(type_info->dset_type)) < 0)
+        local_cause[0] |= H5D_MPIO_ERROR_WHILE_CHECKING_COLLECTIVE_POSSIBLE;
+    else if(is_vl_storage)
+        local_cause[1] |= H5D_MPIO_RANK0_NOT_FIXED_SIZE;
+    else {
+        size_t type_size;       /* Size of dataset's datatype */
+
+        /* Retrieve the size of the dataset's datatype */
+        if(0 == (type_size = H5T_GET_SIZE(type_info->dset_type)))
+            local_cause[0] |= H5D_MPIO_ERROR_WHILE_CHECKING_COLLECTIVE_POSSIBLE;
+        else {
+            hssize_t snelmts;   /* [Signed] # of elements in dataset's dataspace */
+
+            /* Retrieve the size of the dataset's datatype */
+            if((snelmts = H5S_GET_EXTENT_NPOINTS(file_space)) < 0)
+                local_cause[0] |= H5D_MPIO_ERROR_WHILE_CHECKING_COLLECTIVE_POSSIBLE;
+            else {
+                hsize_t dset_size;
+
+                /* Determine dataset size */
+                dset_size = ((hsize_t)snelmts) * type_size;
+
+               /* If the size of the dataset is less than 2GB then do an MPI_Bcast
+                * of the data from one process instead of having all the processes 
+                * involved in the collective I/O.
+                */
+                if(dset_size > ((hsize_t)(2.0F * H5_GB) - 1))
+                    local_cause[1] |= H5D_MPIO_RANK0_GREATER_THAN_2GB;
+            } /* end else */
+        } /* end else */
+    } /* end else */
+    
     /* Check for independent I/O */
-    if(local_cause & H5D_MPIO_SET_INDEPENDENT)
-        global_cause = local_cause;
+    if(local_cause[0] & H5D_MPIO_SET_INDEPENDENT)
+        global_cause[0] = local_cause[0];
     else {
         int mpi_code;               /* MPI error code */
 
         /* Form consensus opinion among all processes about whether to perform
          * collective I/O
          */
-        if(MPI_SUCCESS != (mpi_code = MPI_Allreduce(&local_cause, &global_cause, 1, MPI_UNSIGNED, MPI_BOR, io_info->comm)))
+        if(MPI_SUCCESS != (mpi_code = MPI_Allreduce(&local_cause, &global_cause, 2, MPI_UNSIGNED, MPI_BOR, io_info->comm)))
             HMPI_GOTO_ERROR(FAIL, "MPI_Allreduce failed", mpi_code)
     } /* end else */
 
     /* Set the local & global values of no-collective-cause in the API context */
-    H5CX_set_mpio_local_no_coll_cause(local_cause);
-    H5CX_set_mpio_global_no_coll_cause(global_cause);
+    H5CX_set_mpio_local_no_coll_cause(local_cause[0]);
+    H5CX_set_mpio_global_no_coll_cause(global_cause[0]);
+
+    /* Set read-with-rank0-and-bcast flag if possible */
+    if(global_cause[0] == 0 && global_cause[1] == 0) {
+        H5CX_set_mpio_rank0_bcast(TRUE);
+#ifdef H5_HAVE_INSTRUMENTED_LIBRARY
+        H5CX_test_set_mpio_coll_rank0_bcast(TRUE);
+#endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
+    } /* end if */
 
     /* Set the return value, based on the global cause */
-    ret_value = global_cause > 0 ? FALSE : TRUE;
+    ret_value = global_cause[0] > 0 ? FALSE : TRUE;
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -3069,8 +3134,8 @@ H5D__filtered_collective_chunk_entry_io(H5D_filtered_collective_io_info_t *chunk
         chunk_entry->chunk_states.new_chunk.length = chunk_entry->chunk_states.chunk_current.length;
 
         /* Currently, these chunk reads are done independently and will likely
-	 * cause issues with collective metadata reads enabled. In the future,
-	 * this should be refactored to use collective chunk reads - JTH */
+         * cause issues with collective metadata reads enabled. In the future,
+         * this should be refactored to use collective chunk reads - JTH */
 
         /* Get the original state of parallel I/O transfer mode */
         if(H5CX_get_io_xfer_mode(&xfer_mode) < 0)
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index aaa3db2..6fb7889 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -95,7 +95,13 @@
 /* Definitions for all collective chunk instrumentation properties */
 #define H5D_XFER_COLL_CHUNK_SIZE        sizeof(unsigned)
 #define H5D_XFER_COLL_CHUNK_DEF         1
-#define H5D_XFER_COLL_CHUNK_FIX         0
+
+/* General collective I/O instrumentation properties */
+#define H5D_XFER_COLL_RANK0_BCAST_NAME  "coll_rank0_bcast"
+
+/* Definitions for general collective I/O instrumentation properties */
+#define H5D_XFER_COLL_RANK0_BCAST_SIZE  sizeof(hbool_t)
+#define H5D_XFER_COLL_RANK0_BCAST_DEF   FALSE
 #endif /* H5_HAVE_INSTRUMENTED_LIBRARY */
 
 /* Default temporary buffer size */
diff --git a/src/H5F.c b/src/H5F.c
index 0ff3f1f..9df8140 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -653,11 +653,17 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
     if(H5CX_set_apl(&fapl_id, H5P_CLS_FACC, H5I_INVALID_HID, TRUE) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTSET, H5I_INVALID_HID, "can't set access property list info")
 
-    /* get the VOL info from the fapl */
+    /* Get the VOL info from the fapl */
     if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a file access property list")
     if(H5P_peek(plist, H5F_ACS_VOL_CONN_NAME, &connector_prop) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, H5I_INVALID_HID, "can't get VOL connector info")
+        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "can't get VOL connector info")
+
+    /* Stash a copy of the "top-level" connector property, before any pass-through
+     *  connectors modify or unwrap it.
+     */
+    if(H5CX_set_vol_connector_prop(&connector_prop) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTSET, H5I_INVALID_HID, "can't set VOL connector info in API context")
 
     /* Adjust bit flags by turning on the creation bit and making sure that
      * the EXCL or TRUNC bit is set.  All newly-created files are opened for
@@ -733,7 +739,13 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
     if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a file access property list")
     if(H5P_peek(plist, H5F_ACS_VOL_CONN_NAME, &connector_prop) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, H5I_INVALID_HID, "can't get VOL connector info")
+        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, H5I_INVALID_HID, "can't get VOL connector info")
+
+    /* Stash a copy of the "top-level" connector property, before any pass-through
+     *  connectors modify or unwrap it.
+     */
+    if(H5CX_set_vol_connector_prop(&connector_prop) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTSET, H5I_INVALID_HID, "can't set VOL connector info in API context")
 
     /* Open the file through the VOL layer */
     if(NULL == (new_file = (H5F_t *)H5VL_file_open(&connector_prop, filename, flags, fapl_id, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL)))
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index a5180d0..3ab90aa 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -73,69 +73,69 @@ typedef struct H5FD_mpio_t {
 /* Private Prototypes */
 
 /* Callbacks */
-static herr_t H5FD_mpio_term(void);
-static void *H5FD_mpio_fapl_get(H5FD_t *_file);
-static void *H5FD_mpio_fapl_copy(const void *_old_fa);
-static herr_t H5FD_mpio_fapl_free(void *_fa);
-static H5FD_t *H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
+static herr_t H5FD__mpio_term(void);
+static void *H5FD__mpio_fapl_get(H5FD_t *_file);
+static void *H5FD__mpio_fapl_copy(const void *_old_fa);
+static herr_t H5FD__mpio_fapl_free(void *_fa);
+static H5FD_t *H5FD__mpio_open(const char *name, unsigned flags, hid_t fapl_id,
 			      haddr_t maxaddr);
-static herr_t H5FD_mpio_close(H5FD_t *_file);
-static herr_t H5FD_mpio_query(const H5FD_t *_f1, unsigned long *flags);
-static haddr_t H5FD_mpio_get_eoa(const H5FD_t *_file, H5FD_mem_t type);
-static herr_t H5FD_mpio_set_eoa(H5FD_t *_file, H5FD_mem_t type, haddr_t addr);
-static haddr_t H5FD_mpio_get_eof(const H5FD_t *_file, H5FD_mem_t type);
-static herr_t  H5FD_mpio_get_handle(H5FD_t *_file, hid_t fapl, void** file_handle);
-static herr_t H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
+static herr_t H5FD__mpio_close(H5FD_t *_file);
+static herr_t H5FD__mpio_query(const H5FD_t *_f1, unsigned long *flags);
+static haddr_t H5FD__mpio_get_eoa(const H5FD_t *_file, H5FD_mem_t type);
+static herr_t H5FD__mpio_set_eoa(H5FD_t *_file, H5FD_mem_t type, haddr_t addr);
+static haddr_t H5FD__mpio_get_eof(const H5FD_t *_file, H5FD_mem_t type);
+static herr_t H5FD__mpio_get_handle(H5FD_t *_file, hid_t fapl, void** file_handle);
+static herr_t H5FD__mpio_read(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
             size_t size, void *buf);
-static herr_t H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
+static herr_t H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr,
             size_t size, const void *buf);
-static herr_t H5FD_mpio_flush(H5FD_t *_file, hid_t dxpl_id, hbool_t closing);
-static herr_t H5FD_mpio_truncate(H5FD_t *_file, hid_t dxpl_id, hbool_t closing);
-static int H5FD_mpio_mpi_rank(const H5FD_t *_file);
-static int H5FD_mpio_mpi_size(const H5FD_t *_file);
-static MPI_Comm H5FD_mpio_communicator(const H5FD_t *_file);
-static herr_t  H5FD_mpio_get_info(H5FD_t *_file, void** mpi_info);
+static herr_t H5FD__mpio_flush(H5FD_t *_file, hid_t dxpl_id, hbool_t closing);
+static herr_t H5FD__mpio_truncate(H5FD_t *_file, hid_t dxpl_id, hbool_t closing);
+static int H5FD__mpio_mpi_rank(const H5FD_t *_file);
+static int H5FD__mpio_mpi_size(const H5FD_t *_file);
+static MPI_Comm H5FD__mpio_communicator(const H5FD_t *_file);
+static herr_t H5FD__mpio_get_info(H5FD_t *_file, void** mpi_info);
 
 /* The MPIO file driver information */
 static const H5FD_class_mpi_t H5FD_mpio_g = {
     {   /* Start of superclass information */
     "mpio",					/*name			*/
     HADDR_MAX,					/*maxaddr		*/
-    H5F_CLOSE_SEMI,				/* fc_degree		*/
-    H5FD_mpio_term,                             /*terminate             */
+    H5F_CLOSE_SEMI,				/*fc_degree		*/
+    H5FD__mpio_term,                            /*terminate             */
     NULL,					/*sb_size		*/
     NULL,					/*sb_encode		*/
     NULL,					/*sb_decode		*/
     sizeof(H5FD_mpio_fapl_t),			/*fapl_size		*/
-    H5FD_mpio_fapl_get,				/*fapl_get		*/
-    H5FD_mpio_fapl_copy,			/*fapl_copy		*/
-    H5FD_mpio_fapl_free, 			/*fapl_free		*/
+    H5FD__mpio_fapl_get,			/*fapl_get		*/
+    H5FD__mpio_fapl_copy,			/*fapl_copy		*/
+    H5FD__mpio_fapl_free, 			/*fapl_free		*/
     0,		                		/*dxpl_size		*/
     NULL,					/*dxpl_copy		*/
     NULL,					/*dxpl_free		*/
-    H5FD_mpio_open,				/*open			*/
-    H5FD_mpio_close,				/*close			*/
+    H5FD__mpio_open,				/*open			*/
+    H5FD__mpio_close,				/*close			*/
     NULL,					/*cmp			*/
-    H5FD_mpio_query,		                /*query			*/
+    H5FD__mpio_query,		                /*query			*/
     NULL,					/*get_type_map		*/
     NULL,					/*alloc			*/
     NULL,					/*free			*/
-    H5FD_mpio_get_eoa,				/*get_eoa		*/
-    H5FD_mpio_set_eoa, 				/*set_eoa		*/
-    H5FD_mpio_get_eof,				/*get_eof		*/
-    H5FD_mpio_get_handle,                       /*get_handle            */
-    H5FD_mpio_read,				/*read			*/
-    H5FD_mpio_write,				/*write			*/
-    H5FD_mpio_flush,				/*flush			*/
-    H5FD_mpio_truncate,				/*truncate		*/
+    H5FD__mpio_get_eoa,				/*get_eoa		*/
+    H5FD__mpio_set_eoa, 			/*set_eoa		*/
+    H5FD__mpio_get_eof,				/*get_eof		*/
+    H5FD__mpio_get_handle,                      /*get_handle            */
+    H5FD__mpio_read,				/*read			*/
+    H5FD__mpio_write,				/*write			*/
+    H5FD__mpio_flush,				/*flush			*/
+    H5FD__mpio_truncate,			/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
     H5FD_FLMAP_DICHOTOMY                        /*fl_map                */
     },  /* End of superclass information */
-    H5FD_mpio_mpi_rank,                         /*get_rank              */
-    H5FD_mpio_mpi_size,                         /*get_size              */
-    H5FD_mpio_communicator,                     /*get_comm              */
-    H5FD_mpio_get_info                          /*get_info              */
+    H5FD__mpio_mpi_rank,                        /*get_rank              */
+    H5FD__mpio_mpi_size,                        /*get_size              */
+    H5FD__mpio_communicator,                    /*get_comm              */
+    H5FD__mpio_get_info                         /*get_info              */
 };
 
 #ifdef H5FDmpio_DEBUG
@@ -162,10 +162,13 @@ static int H5FD_mpio_Debug[256] =
 /*--------------------------------------------------------------------------
 NAME
    H5FD__init_package -- Initialize interface-specific information
+
 USAGE
     herr_t H5FD__init_package()
+
 RETURNS
     Non-negative on success/Negative on failure
+
 DESCRIPTION
     Initializes any interface-specific data or routines.  (Just calls
     H5FD_mpio_init currently).
@@ -246,7 +249,7 @@ done:
 
 
 /*---------------------------------------------------------------------------
- * Function:	H5FD_mpio_term
+ * Function:	H5FD__mpio_term
  *
  * Purpose:	Shut down the VFD
  *
@@ -258,15 +261,15 @@ done:
  *---------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_term(void)
+H5FD__mpio_term(void)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
     /* Reset VFL ID */
-    H5FD_MPIO_g=0;
+    H5FD_MPIO_g = 0;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5FD_mpio_term() */
+} /* end H5FD__mpio_term() */
 
 
 /*-------------------------------------------------------------------------
@@ -293,7 +296,6 @@ H5FD_mpio_term(void)
  *              are freed.
  *
  * Return:	Success:	Non-negative
- *
  * 		Failure:	Negative
  *
  * Programmer:	Albert Cheng
@@ -311,10 +313,9 @@ H5Pset_fapl_mpio(hid_t fapl_id, MPI_Comm comm, MPI_Info info)
     FUNC_ENTER_API(FAIL)
     H5TRACE3("e", "iMcMi", fapl_id, comm, info);
 
+    /* Check arguments */
     if(fapl_id == H5P_DEFAULT)
         HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
-
-    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list")
     if(MPI_COMM_NULL == comm)
@@ -349,7 +350,6 @@ done:
  *				modifications to the access property list do
  *				not affect them and it is the responsibility
  *				of the application to free them.
- *
  * 		Failure:	Negative
  *
  * Programmer:	Robb Matzke
@@ -370,6 +370,7 @@ H5Pget_fapl_mpio(hid_t fapl_id, MPI_Comm *comm/*out*/, MPI_Info *info/*out*/)
     FUNC_ENTER_API(FAIL)
     H5TRACE3("e", "ixx", fapl_id, comm, info);
 
+    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(fapl_id, H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list")
     if(H5FD_MPIO != H5P_peek_driver(plist))
@@ -442,10 +443,9 @@ H5Pset_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t xfer_mode)
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "iDt", dxpl_id, xfer_mode);
 
+    /* Check arguments */
     if(dxpl_id == H5P_DEFAULT)
         HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
-
-    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
     if(H5FD_MPIO_INDEPENDENT != xfer_mode && H5FD_MPIO_COLLECTIVE != xfer_mode)
@@ -469,7 +469,6 @@ done:
  * Return:	Success:	Non-negative, with the transfer mode returned
  *				through the XFER_MODE argument if it is
  *				non-null.
- *
  * 		Failure:	Negative
  *
  * Programmer:	Albert Cheng
@@ -486,6 +485,7 @@ H5Pget_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t *xfer_mode/*out*/)
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "ix", dxpl_id, xfer_mode);
 
+    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
 
@@ -527,10 +527,9 @@ H5Pset_dxpl_mpio_collective_opt(hid_t dxpl_id, H5FD_mpio_collective_opt_t opt_mo
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "iDc", dxpl_id, opt_mode);
 
+    /* Check arguments */
     if(dxpl_id == H5P_DEFAULT)
         HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
-
-    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
 
@@ -571,10 +570,9 @@ H5Pset_dxpl_mpio_chunk_opt(hid_t dxpl_id, H5FD_mpio_chunk_opt_t opt_mode)
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "iDh", dxpl_id, opt_mode);
 
+    /* Check arguments */
     if(dxpl_id == H5P_DEFAULT)
         HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
-
-    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
 
@@ -613,10 +611,9 @@ H5Pset_dxpl_mpio_chunk_opt_num(hid_t dxpl_id, unsigned num_chunk_per_proc)
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "iIu", dxpl_id, num_chunk_per_proc);
 
+    /* Check arguments */
     if(dxpl_id == H5P_DEFAULT)
         HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
-
-    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
 
@@ -658,10 +655,9 @@ H5Pset_dxpl_mpio_chunk_opt_ratio(hid_t dxpl_id, unsigned percent_num_proc_per_ch
     FUNC_ENTER_API(FAIL)
     H5TRACE2("e", "iIu", dxpl_id, percent_num_proc_per_chunk);
 
+    /* Check arguments */
     if(dxpl_id == H5P_DEFAULT)
         HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
-
-    /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id, H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl")
 
@@ -675,14 +671,13 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_fapl_get
+ * Function:	H5FD__mpio_fapl_get
  *
  * Purpose:	Returns a file access property list which could be used to
  *		create another file the same as this one.
  *
  * Return:	Success:	Ptr to new file access property list with all
  *				fields copied from the file pointer.
- *
  *		Failure:	NULL
  *
  * Programmer:	Robb Matzke
@@ -691,17 +686,19 @@ done:
  *-------------------------------------------------------------------------
  */
 static void *
-H5FD_mpio_fapl_get(H5FD_t *_file)
+H5FD__mpio_fapl_get(H5FD_t *_file)
 {
     H5FD_mpio_t		*file = (H5FD_mpio_t*)_file;
     H5FD_mpio_fapl_t	*fa = NULL;
     void      *ret_value;       /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
     HDassert(H5FD_MPIO == file->pub.driver_id);
 
+    /* Check arguments */
     if(NULL == (fa = (H5FD_mpio_fapl_t *)H5MM_calloc(sizeof(H5FD_mpio_fapl_t))))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
@@ -714,16 +711,15 @@ H5FD_mpio_fapl_get(H5FD_t *_file)
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD__mpio_fapl_get() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_fapl_copy
+ * Function:	H5FD__mpio_fapl_copy
  *
  * Purpose:	Copies the mpio-specific file access properties.
  *
  * Return:	Success:	Ptr to a new property list
- *
  *		Failure:	NULL
  *
  * Programmer:	Albert Cheng
@@ -732,16 +728,17 @@ done:
  *-------------------------------------------------------------------------
  */
 static void *
-H5FD_mpio_fapl_copy(const void *_old_fa)
+H5FD__mpio_fapl_copy(const void *_old_fa)
 {
-    void		*ret_value = NULL;
     const H5FD_mpio_fapl_t *old_fa = (const H5FD_mpio_fapl_t*)_old_fa;
     H5FD_mpio_fapl_t	*new_fa = NULL;
+    void		*ret_value = NULL;
+
+    FUNC_ENTER_STATIC
 
-    FUNC_ENTER_NOAPI_NOINIT
 #ifdef H5FDmpio_DEBUG
-if (H5FD_mpio_Debug[(int)'t'])
-fprintf(stderr, "enter H5FD_mpio_fapl_copy\n");
+if(H5FD_mpio_Debug[(int)'t'])
+    HDfprintf(stderr, "%s: entering\n", FUNC);
 #endif
 
     if(NULL == (new_fa = (H5FD_mpio_fapl_t *)H5MM_malloc(sizeof(H5FD_mpio_fapl_t))))
@@ -751,65 +748,68 @@ fprintf(stderr, "enter H5FD_mpio_fapl_copy\n");
     HDmemcpy(new_fa, old_fa, sizeof(H5FD_mpio_fapl_t));
 
     /* Duplicate communicator and Info object. */
-    if(FAIL == H5FD_mpi_comm_info_dup(old_fa->comm, old_fa->info, &new_fa->comm, &new_fa->info))
+    if(H5FD_mpi_comm_info_dup(old_fa->comm, old_fa->info, &new_fa->comm, &new_fa->info) < 0)
 	HGOTO_ERROR(H5E_INTERNAL, H5E_CANTCOPY, NULL, "Communicator/Info duplicate failed")
+
+    /* Set return value */
     ret_value = new_fa;
 
 done:
-    if (NULL == ret_value){
+    if(NULL == ret_value)
 	/* cleanup */
-	if (new_fa)
+	if(new_fa)
 	    H5MM_xfree(new_fa);
-    }
 
 #ifdef H5FDmpio_DEBUG
-if (H5FD_mpio_Debug[(int)'t'])
-fprintf(stderr, "leaving H5FD_mpio_fapl_copy\n");
+if(H5FD_mpio_Debug[(int)'t'])
+    HDfprintf(stderr, "%s: leaving\n", FUNC);
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_mpio_fapl_copy() */
+} /* end H5FD__mpio_fapl_copy() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_fapl_free
+ * Function:	H5FD__mpio_fapl_free
  *
  * Purpose:	Frees the mpio-specific file access properties.
  *
  * Return:	Success:	0
- *
  *		Failure:	-1
  *
  * Programmer:	Albert Cheng
  *              Jan  8, 2003
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_fapl_free(void *_fa)
+H5FD__mpio_fapl_free(void *_fa)
 {
-    herr_t		ret_value = SUCCEED;
     H5FD_mpio_fapl_t	*fa = (H5FD_mpio_fapl_t*)_fa;
+    herr_t		ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
 #ifdef H5FDmpio_DEBUG
-if (H5FD_mpio_Debug[(int)'t'])
-fprintf(stderr, "in H5FD_mpio_fapl_free\n");
+if(H5FD_mpio_Debug[(int)'t'])
+    HDfprintf(stderr, "%s: Entering\n", FUNC);
 #endif
+
+    /* Sanity checks */
     HDassert(fa);
 
     /* Free the internal communicator and INFO object */
-    HDassert(MPI_COMM_NULL!=fa->comm);
+    HDassert(MPI_COMM_NULL != fa->comm);
     H5FD_mpi_comm_info_free(&fa->comm, &fa->info);
     H5MM_xfree(fa);
 
 #ifdef H5FDmpio_DEBUG
-if (H5FD_mpio_Debug[(int)'t'])
-fprintf(stderr, "leaving H5FD_mpio_fapl_free\n");
+if(H5FD_mpio_Debug[(int)'t'])
+    HDfprintf(stderr, "%s: leaving\n", FUNC);
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_mpio_fapl_free() */
+} /* end H5FD__mpio_fapl_free() */
 
 
 /*-------------------------------------------------------------------------
@@ -837,26 +837,27 @@ H5FD_set_mpio_atomicity(H5FD_t *_file, hbool_t flag)
     FUNC_ENTER_NOAPI_NOINIT
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Entering H5FD_set_mpio_atomicity\n");
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
 
-    if (FALSE == flag)
+    if(FALSE == flag)
         temp_flag = 0;
     else
         temp_flag = 1;
 
     /* set atomicity value */
-    if (MPI_SUCCESS != (mpi_code=MPI_File_set_atomicity(file->f, temp_flag)))
+    if(MPI_SUCCESS != (mpi_code = MPI_File_set_atomicity(file->f, temp_flag)))
         HMPI_GOTO_ERROR(FAIL, "MPI_File_set_atomicity", mpi_code)
 
 done:
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Leaving H5FD_set_mpio_atomicity\n");
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD_set_mpio_atomicity() */
 
 
 /*-------------------------------------------------------------------------
@@ -884,30 +885,31 @@ H5FD_get_mpio_atomicity(H5FD_t *_file, hbool_t *flag)
     FUNC_ENTER_NOAPI_NOINIT
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Entering H5FD_get_mpio_atomicity\n");
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
 
-    /* get atomicity value */
-    if (MPI_SUCCESS != (mpi_code=MPI_File_get_atomicity(file->f, &temp_flag)))
+    /* Get atomicity value */
+    if(MPI_SUCCESS != (mpi_code = MPI_File_get_atomicity(file->f, &temp_flag)))
         HMPI_GOTO_ERROR(FAIL, "MPI_File_get_atomicity", mpi_code)
 
-    if (0 != temp_flag)
+    if(0 != temp_flag)
         *flag = TRUE;
     else
         *flag = FALSE;
 
 done:
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Leaving H5FD_get_mpio_atomicity\n");
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD_get_mpio_atomicity() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_mpio_open
+ * Function:    H5FD__mpio_open
  *
  * Purpose:     Opens a file with name NAME.  The FLAGS are a bit field with
  *		purpose similar to the second argument of open(2) and which
@@ -917,21 +919,20 @@ done:
  *		access.  This is collective.
  *
  * Return:      Success:        A new file pointer.
- *
  *              Failure:        NULL
  *
- * Programmer:
+ * Programmer:  Robert Kim Yates
  *              January 30, 1998
  *
  *-------------------------------------------------------------------------
  */
 static H5FD_t *
-H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
-	       haddr_t H5_ATTR_UNUSED maxaddr)
+H5FD__mpio_open(const char *name, unsigned flags, hid_t fapl_id,
+    haddr_t H5_ATTR_UNUSED maxaddr)
 {
-    H5FD_mpio_t			*file=NULL;
+    H5FD_mpio_t			*file = NULL;
     MPI_File			fh;
-    unsigned                    file_opened=0;  /* Flag to indicate that the file was successfully opened */
+    unsigned                    file_opened = 0; /* Flag to indicate that the file was successfully opened */
     int				mpi_amode;
     int				mpi_rank;       /* MPI rank of this process */
     int				mpi_size;       /* Total number of MPI processes */
@@ -944,13 +945,11 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
     MPI_Info                    info_dup = MPI_INFO_NULL;
     H5FD_t			*ret_value;     /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t']) {
-    	fprintf(stdout, "Entering H5FD_mpio_open(name=\"%s\", flags=0x%x, "
-		"fapl_id=%d, maxaddr=%lu)\n", name, flags, (int)fapl_id, (unsigned long)maxaddr);
-    }
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Entering - name = \"%s\", flags = 0x%x, fapl_id = %d, maxaddr = %lu\n", FUNC, name, flags, (int)fapl_id, (unsigned long)maxaddr);
 #endif
 
     /* Obtain a pointer to mpio-specific file access properties */
@@ -961,10 +960,9 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
 	_fa.info = MPI_INFO_NULL; /*default*/
 	fa = &_fa;
     } /* end if */
-    else {
+    else
         if(NULL == (fa = (const H5FD_mpio_fapl_t *)H5P_peek_driver_info(plist)))
 	    HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, NULL, "bad VFL driver info")
-    } /* end else */
 
     /* Duplicate communicator and Info object for use by this file. */
     if(FAIL == H5FD_mpi_comm_info_dup(fa->comm, fa->info, &comm_dup, &info_dup))
@@ -980,21 +978,19 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
 
 #ifdef H5FDmpio_DEBUG
     /* Check for debug commands in the info parameter */
-    {
-        if(MPI_INFO_NULL != info_dup) {
-            char debug_str[128];
-            int flag;
-
-            MPI_Info_get(fa->info, H5F_MPIO_DEBUG_KEY, sizeof(debug_str) - 1, debug_str, &flag);
-            if(flag) {
-                int i;
-
-                fprintf(stdout, "H5FD_mpio debug flags = '%s'\n", debug_str);
-                for(i = 0; debug_str[i]/*end of string*/ && i < 128/*just in case*/; ++i)
-                    H5FD_mpio_Debug[(int)debug_str[i]] = 1;
-            }
-        }
-    }
+    if(MPI_INFO_NULL != info_dup) {
+        char debug_str[128];
+        int flag;
+
+        MPI_Info_get(fa->info, H5F_MPIO_DEBUG_KEY, sizeof(debug_str) - 1, debug_str, &flag);
+        if(flag) {
+            int i;
+
+            HDfprintf(stdout, "H5FD_mpio debug flags = '%s'\n", debug_str);
+            for(i = 0; debug_str[i]/*end of string*/ && i < 128/*just in case*/; ++i)
+                H5FD_mpio_Debug[(int)debug_str[i]] = 1;
+        } /* end if */
+    } /* end if */
 #endif
 
     if(MPI_SUCCESS != (mpi_code = MPI_File_open(comm_dup, name, mpi_amode, info_dup, &fh)))
@@ -1044,69 +1040,62 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
     file->local_eof = file->eof;
 
     /* Set return value */
-    ret_value=(H5FD_t*)file;
+    ret_value = (H5FD_t*)file;
 
 done:
-    if(ret_value==NULL) {
+    if(ret_value == NULL) {
         if(file_opened)
             MPI_File_close(&fh);
-	if (MPI_COMM_NULL != comm_dup)
+	if(MPI_COMM_NULL != comm_dup)
 	    MPI_Comm_free(&comm_dup);
-	if (MPI_INFO_NULL != info_dup)
+	if(MPI_INFO_NULL != info_dup)
 	    MPI_Info_free(&info_dup);
-	if (file)
+	if(file)
 	    H5MM_xfree(file);
     } /* end if */
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-        fprintf(stdout, "Leaving H5FD_mpio_open\n" );
+    if(H5FD_mpio_Debug[(int)'t'])
+        HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_mpio_open() */
+} /* end H5FD__mpio_open() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_mpio_close
+ * Function:    H5FD__mpio_close
  *
  * Purpose:     Closes a file.  This is collective.
  *
  * Return:      Success:	Non-negative
- *
  * 		Failure:	Negative
  *
  * Programmer:  Unknown
  *              January 30, 1998
  *
- * Modifications:
- * 		Robb Matzke, 1998-02-18
- *		Added the ACCESS_PARMS argument.
- *
- * 		Robb Matzke, 1999-08-06
- *		Modified to work with the virtual file layer.
- *
- * 		Albert Cheng, 2003-04-17
- *		Free the communicator stored.
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_close(H5FD_t *_file)
+H5FD__mpio_close(H5FD_t *_file)
 {
     H5FD_mpio_t	*file = (H5FD_mpio_t*)_file;
     int		mpi_code;	        /* MPI return code */
-    herr_t      ret_value=SUCCEED;      /* Return value */
+    herr_t      ret_value = SUCCEED;    /* Return value */
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Entering H5FD_mpio_close\n");
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
+
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     /* MPI_File_close sets argument to MPI_FILE_NULL */
-    if (MPI_SUCCESS != (mpi_code=MPI_File_close(&(file->f)/*in,out*/)))
+    if(MPI_SUCCESS != (mpi_code = MPI_File_close(&(file->f)/*in,out*/)))
         HMPI_GOTO_ERROR(FAIL, "MPI_File_close failed", mpi_code)
 
     /* Clean up other stuff */
@@ -1115,45 +1104,36 @@ H5FD_mpio_close(H5FD_t *_file)
 
 done:
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Leaving H5FD_mpio_close\n");
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD__mpio_close() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_query
+ * Function:	H5FD__mpio_query
  *
  * Purpose:	Set the flags that this VFL driver is capable of supporting.
  *              (listed in H5FDpublic.h)
  *
  * Return:	Success:	non-negative
- *
  *		Failure:	negative
  *
  * Programmer:	Quincey Koziol
  *              Friday, August 25, 2000
  *
- * Modifications:
- *
- *		John Mainzer -- 9/21/05
- *		Modified code to turn off the
- *		H5FD_FEAT_ACCUMULATE_METADATA_WRITE flag.
- *              With the movement of
- *		all cache writes to process 0, this flag has become
- *		problematic in PHDF5.
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_query(const H5FD_t H5_ATTR_UNUSED *_file, unsigned long *flags /* out */)
+H5FD__mpio_query(const H5FD_t H5_ATTR_UNUSED *_file, unsigned long *flags /* out */)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
     /* Set the VFL feature flags that this driver supports */
     if(flags) {
-        *flags=0;
+        *flags = 0;
         *flags |= H5FD_FEAT_AGGREGATE_METADATA;     /* OK to aggregate metadata allocations                             */
         *flags |= H5FD_FEAT_AGGREGATE_SMALLDATA;    /* OK to aggregate "small" raw data allocations                     */
         *flags |= H5FD_FEAT_HAS_MPI;                /* This driver uses MPI                                             */
@@ -1162,83 +1142,73 @@ H5FD_mpio_query(const H5FD_t H5_ATTR_UNUSED *_file, unsigned long *flags /* out
     } /* end if */
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-}
+} /* end H5FD__mpio_query() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_get_eoa
+ * Function:	H5FD__mpio_get_eoa
  *
  * Purpose:	Gets the end-of-address marker for the file. The EOA marker
  *		is the first address past the last byte allocated in the
  *		format address space.
  *
  * Return:	Success:	The end-of-address marker.
- *
  *		Failure:	HADDR_UNDEF
  *
  * Programmer:	Robb Matzke
  *              Friday, August  6, 1999
  *
- * Modifications:
- *              Raymond Lu
- *              21 Dec. 2006
- *              Added the parameter TYPE.  It's only used for MULTI driver.
- *
  *-------------------------------------------------------------------------
  */
 static haddr_t
-H5FD_mpio_get_eoa(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
+H5FD__mpio_get_eoa(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
 {
     const H5FD_mpio_t	*file = (const H5FD_mpio_t*)_file;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     FUNC_LEAVE_NOAPI(file->eoa)
-}
+} /* end H5FD__mpio_get_eoa() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_set_eoa
+ * Function:	H5FD__mpio_set_eoa
  *
  * Purpose:	Set the end-of-address marker for the file. This function is
  *		called shortly after an existing HDF5 file is opened in order
  *		to tell the driver where the end of the HDF5 data is located.
  *
  * Return:	Success:	0
- *
  *		Failure:	-1
  *
  * Programmer:	Robb Matzke
  *              Friday, August 6, 1999
  *
- * Modifications:
- *              Raymond Lu
- *              21 Dec. 2006
- *              Added the parameter TYPE.  It's only used for MULTI driver.
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_set_eoa(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, haddr_t addr)
+H5FD__mpio_set_eoa(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, haddr_t addr)
 {
     H5FD_mpio_t	*file = (H5FD_mpio_t*)_file;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     file->eoa = addr;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-}
+} /* end H5FD__mpio_set_eoa() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_get_eof
+ * Function:	H5FD__mpio_get_eof
  *
  * Purpose:	Gets the end-of-file marker for the file. The EOF marker
  *		is the real size of the file.
@@ -1256,32 +1226,30 @@ H5FD_mpio_set_eoa(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, haddr_t addr)
  *              file. -QAK
  *
  * Return:	Success:	The end-of-address marker.
- *
  *		Failure:	HADDR_UNDEF
  *
  * Programmer:	Robb Matzke
  *              Friday, August  6, 1999
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 static haddr_t
-H5FD_mpio_get_eof(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
+H5FD__mpio_get_eof(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
 {
     const H5FD_mpio_t	*file = (const H5FD_mpio_t*)_file;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     FUNC_LEAVE_NOAPI(file->eof)
-}
+} /* end H5FD__mpio_get_eof() */
 
 
 /*-------------------------------------------------------------------------
- * Function:       H5FD_mpio_get_handle
+ * Function:       H5FD__mpio_get_handle
  *
  * Purpose:        Returns the file handle of MPIO file driver.
  *
@@ -1290,17 +1258,15 @@ H5FD_mpio_get_eof(const H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type)
  * Programmer:     Raymond Lu
  *                 Sept. 16, 2002
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
 */
 static herr_t
-H5FD_mpio_get_handle(H5FD_t *_file, hid_t H5_ATTR_UNUSED fapl, void** file_handle)
+H5FD__mpio_get_handle(H5FD_t *_file, hid_t H5_ATTR_UNUSED fapl, void** file_handle)
 {
-    H5FD_mpio_t         *file = (H5FD_mpio_t *)_file;
-    herr_t              ret_value = SUCCEED;
+    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
+    herr_t      ret_value = SUCCEED;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
     if(!file_handle)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "file handle not valid")
@@ -1309,7 +1275,7 @@ H5FD_mpio_get_handle(H5FD_t *_file, hid_t H5_ATTR_UNUSED fapl, void** file_handl
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD__mpio_get_handle() */
 
 
 /*-------------------------------------------------------------------------
@@ -1346,7 +1312,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_read
+ * Function:	H5FD__mpio_read
  *
  * Purpose:	Reads SIZE bytes of data from FILE beginning at address ADDR
  *		into buffer BUF according to data transfer properties in
@@ -1364,85 +1330,41 @@ done:
  *
  * Programmer:	rky, 1998-01-30
  *
- * Modifications:
- * 		Robb Matzke, 1998-02-18
- *		Added the ACCESS_PARMS argument.
- *
- * 		rky, 1998-04-10
- *		Call independent or collective MPI read, based on
- *		ACCESS_PARMS.
- *
- * 		Albert Cheng, 1998-06-01
- *		Added XFER_MODE to control independent or collective MPI
- *		read.
- *
- * 		rky, 1998-08-16
- *		Use BTYPE, FTYPE, and DISP from access parms. The guts of
- *		H5FD_mpio_read and H5FD_mpio_write should be replaced by a
- *		single dual-purpose routine.
- *
- * 		Robb Matzke, 1999-04-21
- *		Changed XFER_MODE to XFER_PARMS for all H5F_*_read()
- *		callbacks.
- *
- * 		Robb Matzke, 1999-07-28
- *		The ADDR argument is passed by value.
- *
- * 		Robb Matzke, 1999-08-06
- *		Modified to work with the virtual file layer.
- *
- *		Quincey Koziol,  2002-05-14
- *		Only call MPI_Get_count if we can use MPI_BYTE for the MPI type
- *              for the I/O transfer.  Someday we might include code to decode
- *              the MPI type used for more complicated transfers and call
- *              MPI_Get_count all the time.
- *
- *              Quincey Koziol - 2002/06/17
- *              Removed 'disp' parameter from H5FD_mpio_setup routine and use
- *              the address of the dataset in MPI_File_set_view() calls, as
- *              necessary.
- *
- *              Quincey Koziol - 2002/06/24
- *              Removed "lazy" MPI_File_set_view() calls, since they would fail
- *              if the first I/O was a collective I/O using MPI derived types
- *              and the next I/O was an independent I/O.
- *
- *              Quincey Koziol - 2003/10/22-31
- *              Restructured code massively, straightening out logic and finally
- *              getting the bytes_read stuff working.
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
+H5FD__mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
     hid_t H5_ATTR_UNUSED dxpl_id, haddr_t addr, size_t size, void *buf/*out*/)
 {
-    H5FD_mpio_t			*file = (H5FD_mpio_t*)_file;
-    MPI_Offset			mpi_off;
-    MPI_Status  		mpi_stat;       /* Status from I/O operation */
-    int				mpi_code;	/* mpi return code */
-    MPI_Datatype		buf_type = MPI_BYTE;      /* MPI description of the selection in memory */
-    int         		size_i;         /* Integer copy of 'size' to read */
+    H5FD_mpio_t *file = (H5FD_mpio_t*)_file;
+    MPI_Offset  mpi_off;
+    MPI_Status  mpi_stat;       /* Status from I/O operation */
+    int         mpi_code;       /* mpi return code */
+    MPI_Datatype buf_type = MPI_BYTE;      /* MPI description of the selection in memory */
+    int         size_i;         /* Integer copy of 'size' to read */
 #if MPI_VERSION >= 3
-    MPI_Count         		bytes_read;     /* Number of bytes read in */
-    MPI_Count                   type_size;      /* MPI datatype used for I/O's size */
-    MPI_Count                   io_size;        /* Actual number of bytes requested */
-    MPI_Count                   n;
+    MPI_Count   bytes_read = 0; /* Number of bytes read in */
+    MPI_Count   type_size;      /* MPI datatype used for I/O's size */
+    MPI_Count   io_size;        /* Actual number of bytes requested */
+    MPI_Count   n;
 #else
-    int                         bytes_read;     /* Number of bytes read in */
-    int                         type_size;      /* MPI datatype used for I/O's size */
-    int                         io_size;        /* Actual number of bytes requested */
-    int         		n;
+    int         bytes_read = 0; /* Number of bytes read in */
+    int         type_size;      /* MPI datatype used for I/O's size */
+    int         io_size;        /* Actual number of bytes requested */
+    int         n;
 #endif
-    hbool_t			use_view_this_time = FALSE;
-    herr_t              	ret_value = SUCCEED;
+    hbool_t     use_view_this_time = FALSE;
+    hbool_t     rank0_bcast = FALSE; /* If read-with-rank0-and-bcast flag was used */
+    herr_t      ret_value = SUCCEED;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Entering H5FD_mpio_read\n" );
+    if(H5FD_mpio_Debug[(int)'t'])
+        HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
+
+    /* Sanity checks */
     HDassert(file);
     HDassert(H5FD_MPIO==file->pub.driver_id);
     HDassert(buf);
@@ -1451,21 +1373,20 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
     HDmemset(&mpi_stat,0,sizeof(MPI_Status));
 
     /* some numeric conversions */
-    if (H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off/*out*/)<0)
+    if(H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off/*out*/) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from haddr to MPI off")
     size_i = (int)size;
-    if ((hsize_t)size_i != size)
+    if((hsize_t)size_i != size)
         HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from size to size_i")
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'r'])
-        fprintf(stdout, "in H5FD_mpio_read  mpi_off=%ld  size_i=%d\n",
-		(long)mpi_off, size_i );
+    if(H5FD_mpio_Debug[(int)'r'])
+        HDfprintf(stdout, "%s: mpi_off = %ld  size_i = %d\n", FUNC, (long)mpi_off, size_i);
 #endif
 
     /* Only look for MPI views for raw data transfers */
     if(type == H5FD_MEM_DRAW) {
-        H5FD_mpio_xfer_t            xfer_mode;   /* I/O transfer mode */
+        H5FD_mpio_xfer_t xfer_mode;   /* I/O transfer mode */
 
         /* Get the transfer mode from the API context */
         if(H5CX_get_io_xfer_mode(&xfer_mode) < 0)
@@ -1477,8 +1398,8 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
          * us to test that btype=ftype=MPI_BYTE (or even MPI_TYPE_NULL, which
          * could mean "use MPI_BYTE" by convention).
          */
-        if(xfer_mode==H5FD_MPIO_COLLECTIVE) {
-            MPI_Datatype		file_type;
+        if(xfer_mode == H5FD_MPIO_COLLECTIVE) {
+            MPI_Datatype file_type;
 
             /* Remember that views are used */
             use_view_this_time = TRUE;
@@ -1505,8 +1426,8 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
         H5FD_mpio_collective_opt_t coll_opt_mode;
 
 #ifdef H5FDmpio_DEBUG
-	if (H5FD_mpio_Debug[(int)'t'])
-	    fprintf(stdout, "H5FD_mpio_read: using MPIO collective mode\n");
+        if(H5FD_mpio_Debug[(int)'r'])
+            HDfprintf(stdout, "%s: using MPIO collective mode\n", FUNC);
 #endif
         /* Get the collective_opt property to check whether the application wants to do IO individually. */
         if(H5CX_get_mpio_coll_opt(&coll_opt_mode) < 0)
@@ -1514,16 +1435,33 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
 
         if(coll_opt_mode == H5FD_MPIO_COLLECTIVE_IO) {
 #ifdef H5FDmpio_DEBUG
-            if(H5FD_mpio_Debug[(int)'t'])
-                fprintf(stdout, "H5FD_mpio_read: doing MPI collective IO\n");
+            if(H5FD_mpio_Debug[(int)'r'])
+                HDfprintf(stdout, "%s: doing MPI collective IO\n", FUNC);
 #endif
-            if(MPI_SUCCESS != (mpi_code = MPI_File_read_at_all(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
-                HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at_all failed", mpi_code)
+            /* Check whether we should read from rank 0 and broadcast to other ranks */
+            if(H5CX_get_mpio_rank0_bcast()) {
+#ifdef H5FDmpio_DEBUG
+                if(H5FD_mpio_Debug[(int)'r'])
+                    HDfprintf(stdout, "%s: doing read-rank0-and-MPI_Bcast\n", FUNC);
+#endif
+                /* Indicate path we've taken */
+                rank0_bcast = TRUE;
+
+                /* Read on rank 0 Bcast to other ranks */
+                if(file->mpi_rank == 0)
+                    if(MPI_SUCCESS != (mpi_code = MPI_File_read_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
+                        HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mpi_code)
+                if(MPI_SUCCESS != (mpi_code = MPI_Bcast(buf, size_i, buf_type, 0, file->comm)))
+                    HMPI_GOTO_ERROR(FAIL, "MPI_Bcast failed", mpi_code)
+            } /* end if */
+            else
+                if(MPI_SUCCESS != (mpi_code = MPI_File_read_at_all(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
+                    HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at_all failed", mpi_code)
         } /* end if */
         else {
 #ifdef H5FDmpio_DEBUG
-            if(H5FD_mpio_Debug[(int)'t'])
-                fprintf(stdout, "H5FD_mpio_read: doing MPI independent IO\n");
+            if(H5FD_mpio_Debug[(int)'r'])
+                HDfprintf(stdout, "%s: doing MPI independent IO\n", FUNC);
 #endif
 
             if(MPI_SUCCESS != (mpi_code = MPI_File_read_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
@@ -1535,52 +1473,65 @@ H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type,
          */
         if(MPI_SUCCESS != (mpi_code = MPI_File_set_view(file->f, (MPI_Offset)0, MPI_BYTE, MPI_BYTE, H5FD_mpi_native_g, file->info)))
             HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mpi_code)
-    } else {
+    } /* end if */
+    else
         if(MPI_SUCCESS != (mpi_code = MPI_File_read_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
             HMPI_GOTO_ERROR(FAIL, "MPI_File_read_at failed", mpi_code)
-    }
 
-    /* How many bytes were actually read? */
+    /* Only retrieve bytes read if this rank _actually_ participated in I/O */
+    if(!rank0_bcast || (rank0_bcast && file->mpi_rank == 0) ) {
+        /* How many bytes were actually read? */
 #if MPI_VERSION >= 3
-    if (MPI_SUCCESS != (mpi_code = MPI_Get_elements_x(&mpi_stat, buf_type, &bytes_read)))
+        if(MPI_SUCCESS != (mpi_code = MPI_Get_elements_x(&mpi_stat, buf_type, &bytes_read)))
 #else
-    if (MPI_SUCCESS != (mpi_code = MPI_Get_elements(&mpi_stat, MPI_BYTE, &bytes_read)))
+        if(MPI_SUCCESS != (mpi_code = MPI_Get_elements(&mpi_stat, MPI_BYTE, &bytes_read)))
 #endif
-        HMPI_GOTO_ERROR(FAIL, "MPI_Get_elements failed", mpi_code)
+            HMPI_GOTO_ERROR(FAIL, "MPI_Get_elements failed", mpi_code)
+    } /* end if */
+ 
+    /* If the rank0-bcast feature was used, broadcast the # of bytes read to
+     * other ranks, which didn't perform any I/O.
+     */
+    /* NOTE: This could be optimized further to be combined with the broadcast
+     *          of the data.  (QAK - 2019/1/2)
+     */
+    if(rank0_bcast)
+        if(MPI_SUCCESS != MPI_Bcast(&bytes_read, 1, MPI_LONG_LONG, 0, file->comm))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Bcast failed", 0)
 
     /* Get the type's size */
 #if MPI_VERSION >= 3
-    if (MPI_SUCCESS != (mpi_code = MPI_Type_size_x(buf_type, &type_size)))
+    if(MPI_SUCCESS != (mpi_code = MPI_Type_size_x(buf_type, &type_size)))
 #else
-    if (MPI_SUCCESS != (mpi_code = MPI_Type_size(buf_type, &type_size)))
+    if(MPI_SUCCESS != (mpi_code = MPI_Type_size(buf_type, &type_size)))
 #endif
         HMPI_GOTO_ERROR(FAIL, "MPI_Type_size failed", mpi_code)
 
     /* Compute the actual number of bytes requested */
-    io_size=type_size*size_i;
+    io_size = type_size * size_i;
 
     /* Check for read failure */
-    if (bytes_read<0 || bytes_read>io_size)
+    if(bytes_read < 0 || bytes_read > io_size)
         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file read failed")
 
     /*
      * This gives us zeroes beyond end of physical MPI file.
      */
-    if ((n=(io_size-bytes_read)) > 0)
+    if((n = (io_size - bytes_read)) > 0)
         HDmemset((char*)buf+bytes_read, 0, (size_t)n);
 
 done:
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Leaving H5FD_mpio_read\n" );
+    if(H5FD_mpio_Debug[(int)'t'])
+       HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
 
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5FD__mpio_read() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_write
+ * Function:	H5FD__mpio_write
  *
  * Purpose:	Writes SIZE bytes of data to FILE beginning at address ADDR
  *		from buffer BUF according to data transfer properties in
@@ -1592,116 +1543,16 @@ done:
  *
  * Return:	Success:	Zero. USE_TYPES and OLD_USE_TYPES in the
  *				access params are altered.
- *
  *		Failure:	-1, USE_TYPES and OLD_USE_TYPES in the
  *				access params may be altered.
  *
- * Programmer:	Unknown
+ * Programmer:	Robert Kim Yates
  *              January 30, 1998
  *
- * Modifications:
- *		rky, 1998-08-28
- *		If the file->allsame flag is set, we assume that all the
- *		procs in the relevant MPI communicator will write identical
- *		data at identical offsets in the file, so only proc 0 will
- *		write, and all other procs will wait for p0 to finish. This
- *		is useful for writing metadata, for example. Note that we
- *		don't _check_ that the data is identical. Also, the mechanism
- *		we use to eliminate the redundant writes is by requiring a
- *		call to H5FD_mpio_tas_allsame before the write, which is
- *		rather klugey. Would it be better to pass a parameter to
- *		low-level writes like H5F_block_write and H5F_low_write,
- *		instead?  Or...??? Also, when I created this mechanism I
- *		wanted to minimize the difference in behavior between the old
- *		way of doing things (i.e., all procs write) and the new way,
- *		so the writes are eliminated at the very lowest level, here
- *		in H5FD_mpio_write. It may be better to rethink that, and
- *		short-circuit the writes at a higher level (e.g., at the
- *		points in the code where H5FD_mpio_tas_allsame is called).
- *
- *
- * 		Robb Matzke, 1998-02-18
- *		Added the ACCESS_PARMS argument.
- *
- * 		rky, 1998-04-10
- *		Call independent or collective MPI write, based on
- *		ACCESS_PARMS.
- *
- * 		rky, 1998-04-24
- *		Removed redundant write from H5FD_mpio_write.
- *
- * 		Albert Cheng, 1998-06-01
- *		Added XFER_MODE to control independent or collective MPI
- *		write.
- *
- * 		rky, 1998-08-16
- *		Use BTYPE, FTYPE, and DISP from access parms. The guts of
- *		H5FD_mpio_read and H5FD_mpio_write should be replaced by a
- *		single dual-purpose routine.
- *
- * 		rky, 1998-08-28
- *		Added ALLSAME parameter to make all but proc 0 skip the
- *		actual write.
- *
- * 		Robb Matzke, 1999-04-21
- *		Changed XFER_MODE to XFER_PARMS for all H5FD_*_write()
- *		callbacks.
- *
- * 		Robb Matzke, 1999-07-28
- *		The ADDR argument is passed by value.
- *
- * 		Robb Matzke, 1999-08-06
- *		Modified to work with the virtual file layer.
- *
- *		Albert Cheng, 1999-12-19
- *		When only-p0-write-allsame-data, p0 Bcasts the
- *		ret_value to other processes.  This prevents
- *		a racing condition (that other processes try to
- *		read the file before p0 finishes writing) and also
- *		allows all processes to report the same ret_value.
- *
- *		Kim Yates, Pat Weidhaas,  2000-09-26
- *		Move block of coding where only p0 writes after the
- *              MPI_File_set_view call.
- *
- *		Quincey Koziol,  2002-05-10
- *		Instead of always writing metadata from process 0, spread the
- *              burden among all the processes by using a round-robin rotation
- *              scheme.
- *
- *		Quincey Koziol,  2002-05-10
- *		Removed allsame code, keying off the type parameter instead.
- *
- *		Quincey Koziol,  2002-05-14
- *		Only call MPI_Get_count if we can use MPI_BYTE for the MPI type
- *              for the I/O transfer.  Someday we might include code to decode
- *              the MPI type used for more complicated transfers and call
- *              MPI_Get_count all the time.
- *
- *              Quincey Koziol - 2002/06/17
- *              Removed 'disp' parameter from H5FD_mpio_setup routine and use
- *              the address of the dataset in MPI_File_set_view() calls, as
- *              necessary.
- *
- *              Quincey Koziol - 2002/06/24
- *              Removed "lazy" MPI_File_set_view() calls, since they would fail
- *              if the first I/O was a collective I/O using MPI derived types
- *              and the next I/O was an independent I/O.
- *
- *              Quincey Koziol - 2002/07/18
- *              Added "block_before_meta_write" dataset transfer flag, which
- *              is set during writes from a metadata cache flush and indicates
- *              that all the processes must sync up before (one of them)
- *              writing metadata.
- *
- *              Quincey Koziol - 2003/10/22-31
- *              Restructured code massively, straightening out logic and finally
- *              getting the bytes_written stuff working.
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
+H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
     haddr_t addr, size_t size, const void *buf)
 {
     H5FD_mpio_t			*file = (H5FD_mpio_t*)_file;
@@ -1723,12 +1574,14 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
     H5FD_mpio_xfer_t            xfer_mode;   /* I/O transfer mode */
     herr_t              	ret_value = SUCCEED;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
 #ifdef H5FDmpio_DEBUG
-    if (H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "Entering H5FD_mpio_write\n" );
+    if(H5FD_mpio_Debug[(int)'t'])
+    	HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
+
+    /* Sanity checks */
     HDassert(file);
     HDassert(H5FD_MPIO==file->pub.driver_id);
     HDassert(buf);
@@ -1748,7 +1601,7 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
 
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'w'])
-        fprintf(stdout, "in H5FD_mpio_write  mpi_off=%ld  size_i=%d\n", (long)mpi_off, size_i);
+        HDfprintf(stdout, "%s: mpi_off = %ld  size_i = %d\n", FUNC, (long)mpi_off, size_i);
 #endif
 
     /* Get the transfer mode from the API context */
@@ -1788,8 +1641,8 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
         H5FD_mpio_collective_opt_t coll_opt_mode;
 
 #ifdef H5FDmpio_DEBUG
-        if(H5FD_mpio_Debug[(int)'t'])
-            fprintf(stdout, "H5FD_mpio_write: using MPIO collective mode\n");
+        if(H5FD_mpio_Debug[(int)'w'])
+            HDfprintf(stdout, "%s: using MPIO collective mode\n", FUNC);
 #endif
 
         /* Get the collective_opt property to check whether the application wants to do IO individually. */
@@ -1798,8 +1651,8 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
 
         if(coll_opt_mode == H5FD_MPIO_COLLECTIVE_IO) {
 #ifdef H5FDmpio_DEBUG
-            if(H5FD_mpio_Debug[(int)'t'])
-                fprintf(stdout, "H5FD_mpio_write: doing MPI collective IO\n");
+            if(H5FD_mpio_Debug[(int)'w'])
+                HDfprintf(stdout, "%s: doing MPI collective IO\n", FUNC);
 #endif
             if(MPI_SUCCESS != (mpi_code = MPI_File_write_at_all(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                 HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at_all failed", mpi_code)
@@ -1808,8 +1661,8 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
             if(type != H5FD_MEM_DRAW)
                 HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "Metadata Coll opt property should be collective at this point")
 #ifdef H5FDmpio_DEBUG
-            if(H5FD_mpio_Debug[(int)'t'])
-                fprintf(stdout, "H5FD_mpio_write: doing MPI independent IO\n");
+            if(H5FD_mpio_Debug[(int)'w'])
+                HDfprintf(stdout, "%s: doing MPI independent IO\n", FUNC);
 #endif
             if(MPI_SUCCESS != (mpi_code = MPI_File_write_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
                 HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at failed", mpi_code)
@@ -1818,10 +1671,10 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
         /* Reset the file view when we used MPI derived types */
         if(MPI_SUCCESS != (mpi_code = MPI_File_set_view(file->f, (MPI_Offset)0, MPI_BYTE, MPI_BYTE, H5FD_mpi_native_g,  file->info)))
             HMPI_GOTO_ERROR(FAIL, "MPI_File_set_view failed", mpi_code)
-    } else {
+    } /* end if */
+    else
         if(MPI_SUCCESS != (mpi_code = MPI_File_write_at(file->f, mpi_off, buf, size_i, buf_type, &mpi_stat)))
             HMPI_GOTO_ERROR(FAIL, "MPI_File_write_at failed", mpi_code)
-    }
 
     /* How many bytes were actually written? */
 #if MPI_VERSION >= 3
@@ -1860,15 +1713,15 @@ H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
 done:
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'t'])
-    	fprintf(stdout, "proc %d: Leaving H5FD_mpio_write with ret_value=%d\n",
-	    file->mpi_rank, ret_value );
+    	HDfprintf(stdout, "%s: Leaving, proc %d: ret_value = %d\n", FUNC, file->mpi_rank, ret_value );
 #endif
+
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_mpio_write() */
+} /* end H5FD__mpio_write() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_mpio_flush
+ * Function:    H5FD__mpio_flush
  *
  * Purpose:     Makes sure that all data is on disk.  This is collective.
  *
@@ -1882,18 +1735,20 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_flush(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t closing)
+H5FD__mpio_flush(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t closing)
 {
     H5FD_mpio_t		*file = (H5FD_mpio_t*)_file;
     int			mpi_code;	/* mpi return code */
     herr_t              ret_value = SUCCEED;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'t'])
-    	HDfprintf(stdout, "Entering %s\n", FUNC);
+    	HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
+
+    /* Sanity checks */
     HDassert(file);
     HDassert(H5FD_MPIO == file->pub.driver_id);
 
@@ -1905,15 +1760,15 @@ H5FD_mpio_flush(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t closing)
 done:
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'t'])
-    	HDfprintf(stdout, "Leaving %s\n", FUNC);
+    	HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_mpio_flush() */
+} /* end H5FD__mpio_flush() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5FD_mpio_truncate
+ * Function:    H5FD__mpio_truncate
  *
  * Purpose:     Make certain the file's size matches it's allocated size
  *
@@ -1933,31 +1788,22 @@ done:
  * Programmer:  Quincey Koziol
  *              January 31, 2008
  *
- * Changes:     Heavily reworked to avoid unnecessary MPI_File_set_size()
- *              calls.  The hope is that these calls are superfluous in the
- *              typical case, allowing us to avoid truncates most of the 
- *              time.
- *
- *              The basic idea is to query the file system to get the 
- *              current eof, and only truncate if the file systems 
- *              conception of the eof disagrees with our eoa.
- *
- *                                                 JRM -- 10/27/17
- *
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5FD_mpio_truncate(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t H5_ATTR_UNUSED closing)
+H5FD__mpio_truncate(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t H5_ATTR_UNUSED closing)
 {
-    H5FD_mpio_t		*file = (H5FD_mpio_t*)_file;
-    herr_t              ret_value = SUCCEED;
+    H5FD_mpio_t	*file = (H5FD_mpio_t*)_file;
+    herr_t      ret_value = SUCCEED;
 
-    FUNC_ENTER_NOAPI_NOINIT
+    FUNC_ENTER_STATIC
 
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'t'])
-    	HDfprintf(stdout, "Entering %s\n", FUNC);
+    	HDfprintf(stdout, "%s: Entering\n", FUNC);
 #endif
+
+    /* Sanity checks */
     HDassert(file);
     HDassert(H5FD_MPIO == file->pub.driver_id);
 
@@ -2023,15 +1869,15 @@ H5FD_mpio_truncate(H5FD_t *_file, hid_t H5_ATTR_UNUSED dxpl_id, hbool_t H5_ATTR_
 done:
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'t'])
-    	HDfprintf(stdout, "Leaving %s\n", FUNC);
+    	HDfprintf(stdout, "%s: Leaving\n", FUNC);
 #endif
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5FD_mpio_truncate() */
+} /* end H5FD__mpio_truncate() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_mpi_rank
+ * Function:	H5FD__mpio_mpi_rank
  *
  * Purpose:	Returns the MPI rank for a process
  *
@@ -2041,26 +1887,25 @@ done:
  * Programmer:	Quincey Koziol
  *              Thursday, May 16, 2002
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 static int
-H5FD_mpio_mpi_rank(const H5FD_t *_file)
+H5FD__mpio_mpi_rank(const H5FD_t *_file)
 {
     const H5FD_mpio_t	*file = (const H5FD_mpio_t*)_file;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     FUNC_LEAVE_NOAPI(file->mpi_rank)
-} /* end H5FD_mpio_mpi_rank() */
+} /* end H5FD__mpio_mpi_rank() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_mpi_size
+ * Function:	H5FD__mpio_mpi_size
  *
  * Purpose:	Returns the number of MPI processes
  *
@@ -2070,26 +1915,25 @@ H5FD_mpio_mpi_rank(const H5FD_t *_file)
  * Programmer:	Quincey Koziol
  *              Thursday, May 16, 2002
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 static int
-H5FD_mpio_mpi_size(const H5FD_t *_file)
+H5FD__mpio_mpi_size(const H5FD_t *_file)
 {
     const H5FD_mpio_t	*file = (const H5FD_mpio_t*)_file;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     FUNC_LEAVE_NOAPI(file->mpi_size)
-} /* end H5FD_mpio_mpi_size() */
+} /* end H5FD__mpio_mpi_size() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FD_mpio_communicator
+ * Function:	H5FD__mpio_communicator
  *
  * Purpose:	Returns the MPI communicator for the file.
  *
@@ -2100,22 +1944,53 @@ H5FD_mpio_mpi_size(const H5FD_t *_file)
  * Programmer:	Robb Matzke
  *              Monday, August  9, 1999
  *
- * Modifications:
- *
  *-------------------------------------------------------------------------
  */
 static MPI_Comm
-H5FD_mpio_communicator(const H5FD_t *_file)
+H5FD__mpio_communicator(const H5FD_t *_file)
 {
     const H5FD_mpio_t	*file = (const H5FD_mpio_t*)_file;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC
 
+    /* Sanity checks */
     HDassert(file);
-    HDassert(H5FD_MPIO==file->pub.driver_id);
+    HDassert(H5FD_MPIO == file->pub.driver_id);
 
     FUNC_LEAVE_NOAPI(file->comm)
-} /* end H5FD_mpio_communicator() */
+} /* end H5FD__mpio_communicator() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:       H5FD__mpio_get_info
+ *
+ * Purpose:        Returns the file info of MPIO file driver.
+ *
+ * Returns:        Non-negative if succeed or negative if fails.
+ *
+ * Programmer:     John Mainzer
+ *                 April 4, 2017
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+*/
+static herr_t
+H5FD__mpio_get_info(H5FD_t *_file, void **mpi_info)
+{
+    H5FD_mpio_t *file = (H5FD_mpio_t *)_file;
+    herr_t      ret_value = SUCCEED;
+
+    FUNC_ENTER_STATIC
+
+    if(!mpi_info)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "mpi info not valid")
+
+    *mpi_info = &(file->info);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5FD__mpio_get_info() */
 
 #endif /* H5_HAVE_PARALLEL */
 
diff --git a/src/H5Fefc.c b/src/H5Fefc.c
index a394071..f3881d4 100644
--- a/src/H5Fefc.c
+++ b/src/H5Fefc.c
@@ -29,8 +29,10 @@
 
 /* Packages needed by this file... */
 #include "H5private.h"          /* Generic Functions                    */
+#include "H5CXprivate.h"        /* API Contexts                         */
 #include "H5Eprivate.h"         /* Error handling                       */
 #include "H5Fpkg.h"             /* File access                          */
+#include "H5Iprivate.h"         /* IDs                                  */
 #include "H5MMprivate.h"        /* Memory management                    */
 #include "H5Pprivate.h"         /* Property lists                       */
 
@@ -144,6 +146,8 @@ H5F__efc_open(H5F_t *parent, const char *name, unsigned flags, hid_t fcpl_id, hi
     H5F_efc_t   *efc = NULL;    /* External file cache for parent file */
     H5F_efc_ent_t *ent = NULL;  /* Entry for target file in efc */
     hbool_t     open_file = FALSE; /* Whether ent->file needs to be closed in case of error */
+    H5P_genplist_t *plist;      /* Property list pointer for FAPL */
+    H5VL_connector_prop_t connector_prop; /* Property for VOL connector ID & info        */
     H5F_t       *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_PACKAGE
@@ -153,6 +157,18 @@ H5F__efc_open(H5F_t *parent, const char *name, unsigned flags, hid_t fcpl_id, hi
     HDassert(parent->shared);
     HDassert(name);
 
+    /* Get the VOL info from the fapl */
+    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+        HGOTO_ERROR(H5E_FILE, H5E_BADTYPE, NULL, "not a file access property list")
+    if(H5P_peek(plist, H5F_ACS_VOL_CONN_NAME, &connector_prop) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "can't get VOL connector info")
+
+    /* Stash a copy of the "top-level" connector property, before any pass-through
+     *  connectors modify or unwrap it.
+     */
+    if(H5CX_set_vol_connector_prop(&connector_prop) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTSET, NULL, "can't set VOL connector info in API context")
+
     /* Get external file cache */
     efc = parent->shared->efc;
 
diff --git a/src/H5Fint.c b/src/H5Fint.c
index cca46d0..8a7019d 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -76,7 +76,7 @@ typedef struct H5F_olist_t {
 /* Local Prototypes */
 /********************/
 
-static herr_t H5F__set_vol_conn(H5F_t *file, hid_t vol_id, const void *vol_info);
+static herr_t H5F__set_vol_conn(H5F_t *file);
 static herr_t H5F__get_objects(const H5F_t *f, unsigned types, size_t max_index, hid_t *obj_id_list, hbool_t app_ref, size_t *obj_id_count_ptr);
 static int H5F__get_objects_cb(void *obj_ptr, hid_t obj_id, void *key);
 static herr_t H5F__build_name(const char *prefix, const char *file_name, char **full_name/*out*/);
@@ -119,8 +119,9 @@ H5FL_DEFINE(H5F_file_t);
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5F__set_vol_conn(H5F_t *file, hid_t vol_id, const void *vol_info)
+H5F__set_vol_conn(H5F_t *file)
 {
+    H5VL_connector_prop_t connector_prop; /* Property for VOL connector ID & info */
     void *new_connector_info = NULL;    /* Copy of connector info */
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -129,21 +130,30 @@ H5F__set_vol_conn(H5F_t *file, hid_t vol_id, const void *vol_info)
     /* Sanity check */
     HDassert(file);
 
+    /* Retrieve a copy of the "top-level" connector property, before any pass-through
+     *  connectors modified or unwrapped it.
+     */
+    if(H5CX_get_vol_connector_prop(&connector_prop) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTGET, FAIL, "can't get VOL connector info from API context")
+
+    /* Sanity check */
+    HDassert(0 != connector_prop.connector_id);
+
     /* Copy connector info, if it exists */
-    if(vol_info) {
+    if(connector_prop.connector_info) {
         H5VL_class_t *connector;           /* Pointer to connector */
 
         /* Retrieve the connector for the ID */
-        if(NULL == (connector = (H5VL_class_t *)H5I_object(vol_id)))
+        if(NULL == (connector = (H5VL_class_t *)H5I_object(connector_prop.connector_id)))
             HGOTO_ERROR(H5E_FILE, H5E_BADTYPE, FAIL, "not a VOL connector ID")
 
         /* Allocate and copy connector info */
-        if(H5VL_copy_connector_info(connector, &new_connector_info, vol_info) < 0)
+        if(H5VL_copy_connector_info(connector, &new_connector_info, connector_prop.connector_info) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTCOPY, FAIL, "connector info copy failed")
     } /* end if */
 
     /* Cache the connector ID & info for the container */
-    file->shared->vol_id = vol_id;
+    file->shared->vol_id = connector_prop.connector_id;
     file->shared->vol_info = new_connector_info;
     if(H5I_inc_ref(file->shared->vol_id, FALSE) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "incrementing VOL connector ID failed")
@@ -792,14 +802,12 @@ H5F_prefix_open_file(H5F_t *primary_file, H5F_prefix_open_t prefix_type,
 
         /* get last component of file_name */
         H5_GET_LAST_DELIMITER(actual_file_name, ptr)
-        if(!ptr)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to open file, file name = '%s', temp_file_name = '%s'", file_name, temp_file_name)
-
-        /* Truncate filename portion from actual file name path */
-        *ptr = '\0';
+        if(ptr)
+            /* Truncate filename portion from actual file name path */
+            *ptr = '\0';
 
         /* Build new file name for the external file */
-        if(H5F__build_name(actual_file_name, temp_file_name, &full_name/*out*/) < 0)
+        if(H5F__build_name((ptr ? actual_file_name : ""), temp_file_name, &full_name/*out*/) < 0)
             HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "can't prepend prefix to filename")
         actual_file_name = (char *)H5MM_xfree(actual_file_name);
 
@@ -815,7 +823,7 @@ H5F_prefix_open_file(H5F_t *primary_file, H5F_prefix_open_t prefix_type,
             H5E_clear_stack(NULL);
     } /* end if */
 
-    /* Success */
+    /* Set return value (possibly NULL or valid H5F_t *) */
     ret_value = src_file;
 
 done:
@@ -1090,14 +1098,8 @@ H5F__new(H5F_file_t *shared, unsigned flags, hid_t fcpl_id, hid_t fapl_id, H5FD_
             HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "can't get object flush cb info")
 
         /* Get the VOL connector info */
-        {
-            H5VL_connector_prop_t  connector_prop;      /* Property for VOL connector ID & info */
-
-            if(H5P_peek(plist, H5F_ACS_VOL_CONN_NAME, &connector_prop) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTGET, NULL, "can't get VOL connector info")
-            if(H5F__set_vol_conn(f, connector_prop.connector_id, connector_prop.connector_info) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "can't cache VOL connector info")
-        } /* end block */
+        if(H5F__set_vol_conn(f) < 0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "can't cache VOL connector info")
 
         /* Create a metadata cache with the specified number of elements.
          * The cache might be created with a different number of elements and
diff --git a/src/H5Fpublic.h b/src/H5Fpublic.h
index c4bf0b4..9f1ed01 100644
--- a/src/H5Fpublic.h
+++ b/src/H5Fpublic.h
@@ -234,7 +234,7 @@ H5_DLL herr_t H5Fflush(hid_t object_id, H5F_scope_t scope);
 H5_DLL herr_t H5Fclose(hid_t file_id);
 H5_DLL hid_t  H5Fget_create_plist(hid_t file_id);
 H5_DLL hid_t  H5Fget_access_plist(hid_t file_id);
-H5_DLL herr_t H5Fget_intent(hid_t file_id, unsigned * intent);
+H5_DLL herr_t H5Fget_intent(hid_t file_id, unsigned *intent);
 H5_DLL ssize_t H5Fget_obj_count(hid_t file_id, unsigned types);
 H5_DLL ssize_t H5Fget_obj_ids(hid_t file_id, unsigned types, size_t max_objs, hid_t *obj_id_list);
 H5_DLL herr_t H5Fget_vfd_handle(hid_t file_id, hid_t fapl, void **file_handle);
diff --git a/src/H5Obogus.c b/src/H5Obogus.c
index fbf04f2..f3cca0f 100644
--- a/src/H5Obogus.c
+++ b/src/H5Obogus.c
@@ -49,7 +49,7 @@ const H5O_msg_class_t H5O_MSG_BOGUS_VALID[1] = {{
     H5O_BOGUS_VALID_ID,		/*message id number             */
     "bogus valid",             	/*message name for debugging    */
     0,     	                /*native message size           */
-    0,				/* messages are sharable?       */
+    H5O_SHARE_IS_SHARABLE,      /* messages are sharable?       */
     H5O__bogus_decode,        	/*decode message                */
     H5O_bogus_encode,        	/*encode message                */
     NULL,          	        /*copy the native value         */
@@ -73,7 +73,7 @@ const H5O_msg_class_t H5O_MSG_BOGUS_INVALID[1] = {{
     H5O_BOGUS_INVALID_ID, 	/*message id number             */
     "bogus invalid",          	/*message name for debugging    */
     0,                          /*native message size           */
-    0,                          /* messages are sharable?       */
+    H5O_SHARE_IS_SHARABLE,      /* messages are sharable?       */
     H5O__bogus_decode,          /*decode message                */
     H5O_bogus_encode,           /*encode message                */
     NULL,                       /*copy the native value         */
diff --git a/src/H5Ocache.c b/src/H5Ocache.c
index d32a217..578cff0 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -1403,10 +1403,9 @@ H5O__chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len, const uint8_t *image
             HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "bad flag combination for message")
         if((flags & H5O_MSG_FLAG_WAS_UNKNOWN) && !(flags & H5O_MSG_FLAG_MARK_IF_UNKNOWN))
             HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "bad flag combination for message")
-        if((flags & H5O_MSG_FLAG_SHAREABLE)
-                && H5O_msg_class_g[id]
-                && !(H5O_msg_class_g[id]->share_flags & H5O_SHARE_IS_SHARABLE))
-            HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "message of unsharable class flagged as sharable")
+        /* Delay checking the "shareable" flag until we've made sure id
+         * references a valid message class that this version of the library
+         * knows about */
 
         /* Reserved bytes/creation index */
         if(oh->version == H5O_VERSION_1)
@@ -1518,9 +1517,17 @@ H5O__chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len, const uint8_t *image
                     mesgs_modified = TRUE;
                 } /* end if */
             } /* end if */
-            else
+            else {
+                /* Check for message of unshareable class marked as "shareable"
+                 */
+                if((flags & H5O_MSG_FLAG_SHAREABLE)
+                        && H5O_msg_class_g[id]
+                        && !(H5O_msg_class_g[id]->share_flags & H5O_SHARE_IS_SHARABLE))
+                    HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "message of unshareable class flagged as shareable")
+
                 /* Set message class for "known" messages */
                 mesg->type = H5O_msg_class_g[id];
+            } /* end else */
 
             /* Do some inspection/interpretation of new messages from this chunk */
             /* (detect continuation messages, ref. count messages, etc.) */
diff --git a/src/H5Oint.c b/src/H5Oint.c
index 2503eb7..d3a409c 100644
--- a/src/H5Oint.c
+++ b/src/H5Oint.c
@@ -125,12 +125,7 @@ const H5O_msg_class_t *const H5O_msg_class_g[] = {
     H5O_MSG_REFCOUNT,		/*0x0016 Object's ref. count		*/
     H5O_MSG_FSINFO,		/*0x0017 Free-space manager info        */
     H5O_MSG_MDCI,               /*0x0018 Metadata cache image           */
-    H5O_MSG_UNKNOWN,		/*0x0019 Placeholder for unknown message */
-#ifdef H5O_ENABLE_BOGUS
-    H5O_MSG_BOGUS_INVALID, 	/*0x001A "Bogus invalid" (for testing) 	*/
-#else /* H5O_ENABLE_BOGUS */
-    NULL,                       /*0x001A "Bogus invalid" (for testing) 	*/
-#endif /* H5O_ENABLE_BOGUS */
+    H5O_MSG_UNKNOWN		/*0x0019 Placeholder for unknown message */
 };
 
 /* Format version bounds for object header */
diff --git a/src/H5Omessage.c b/src/H5Omessage.c
index d6e3dce..18f3706 100644
--- a/src/H5Omessage.c
+++ b/src/H5Omessage.c
@@ -1598,16 +1598,23 @@ H5O_msg_is_shared(unsigned type_id, const void *mesg)
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
     /* Check args */
-    HDassert(type_id < NELMTS(H5O_msg_class_g));
-    type = H5O_msg_class_g[type_id];    /* map the type ID to the actual type object */
-    HDassert(type);
-    HDassert(mesg);
-
-    /* If messages in a class aren't sharable, then obviously this message isn't shared! :-) */
-    if(type->share_flags & H5O_SHARE_IS_SHARABLE)
-        ret_value = H5O_IS_STORED_SHARED(((const H5O_shared_t *)mesg)->type);
-    else
+#ifdef H5O_ENABLE_BOGUS
+    if(type_id >= NELMTS(H5O_msg_class_g))
         ret_value = FALSE;
+    else
+#endif /* H5O_ENABLE_BOGUS */
+    {
+        HDassert(type_id < NELMTS(H5O_msg_class_g));
+        type = H5O_msg_class_g[type_id];    /* map the type ID to the actual type object */
+        HDassert(type);
+        HDassert(mesg);
+
+        /* If messages in a class aren't sharable, then obviously this message isn't shared! :-) */
+        if(type->share_flags & H5O_SHARE_IS_SHARABLE)
+            ret_value = H5O_IS_STORED_SHARED(((const H5O_shared_t *)mesg)->type);
+        else
+            ret_value = FALSE;
+    } /* end block/else */
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5O_msg_is_shared() */
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index dbc8089..668f4f0 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -29,7 +29,7 @@
 #define H5O_NMESGS	8 		/*initial number of messages	     */
 #define H5O_NCHUNKS	2		/*initial number of chunks	     */
 #define H5O_MIN_SIZE	22		/* Min. obj header data size (must be big enough for a message prefix and a continuation message) */
-#define H5O_MSG_TYPES   27              /* # of types of messages            */
+#define H5O_MSG_TYPES   26              /* # of types of messages            */
 #define H5O_MAX_CRT_ORDER_IDX 65535     /* Max. creation order index value   */
 
 /* Versions of object header structure */
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index e0926e2..5987ecf 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -227,11 +227,11 @@ typedef struct H5O_copy_t {
  * Note: Must increment H5O_MSG_TYPES in H5Opkg.h and update H5O_msg_class_g
  *      in H5O.c when creating a new message type.  Also bump the value of
  *      H5O_BOGUS_INVALID_ID, below, to be one greater than the value of
- *      H5O_UNKNOWN_ID.
+ *      H5O_UNKNOWN_ID, and re-run gen_bogus.c.
  *
  * (this should never exist in a file)
  */
-#define H5O_BOGUS_INVALID_ID	0x001A  /* "Bogus invalid" Message.  */
+#define H5O_BOGUS_INVALID_ID	0x001a  /* "Bogus invalid" Message.  */
 
 /* Shared object message types.
  * Shared objects can be committed, in which case the shared message contains
@@ -651,6 +651,7 @@ typedef struct H5O_layout_t {
  */
 #define H5O_BOGUS_VALUE         0xdeadbeef
 typedef struct H5O_bogus_t {
+    H5O_shared_t        sh_loc;         /* Shared message info (must be first) */
     unsigned u;                         /* Hold the bogus info */
 } H5O_bogus_t;
 #endif /* H5O_ENABLE_BOGUS */
diff --git a/src/H5Pdxpl.c b/src/H5Pdxpl.c
index bfc1d93..8338d84 100644
--- a/src/H5Pdxpl.c
+++ b/src/H5Pdxpl.c
@@ -2017,6 +2017,7 @@ done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Pget_mpio_actual_io_mode() */
 
+
 /*-------------------------------------------------------------------------
  * Function:	H5Pget_mpio_no_collective_cause
  *
@@ -2053,8 +2054,6 @@ H5Pget_mpio_no_collective_cause(hid_t plist_id, uint32_t *local_no_collective_ca
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Pget_mpio_no_collective_cause() */
-
-
 #endif /* H5_HAVE_PARALLEL */
 
 
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 2f094ea..078fe74 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -167,7 +167,8 @@ typedef enum H5D_mpio_no_collective_cause_t {
     H5D_MPIO_NOT_SIMPLE_OR_SCALAR_DATASPACES = 0x10,
     H5D_MPIO_NOT_CONTIGUOUS_OR_CHUNKED_DATASET = 0x20,
     H5D_MPIO_PARALLEL_FILTERED_WRITES_DISABLED = 0x40,
-    H5D_MPIO_NO_COLLECTIVE_MAX_CAUSE = 0x80
+    H5D_MPIO_ERROR_WHILE_CHECKING_COLLECTIVE_POSSIBLE = 0x80,
+    H5D_MPIO_NO_COLLECTIVE_MAX_CAUSE = 0x100
 } H5D_mpio_no_collective_cause_t;
 
 /********************/
diff --git a/src/H5S.c b/src/H5S.c
index 4c11268..2faf540 100644
--- a/src/H5S.c
+++ b/src/H5S.c
@@ -237,26 +237,25 @@ H5S_get_validated_dataspace(hid_t space_id, const H5S_t **space)
 
     HDassert(space);
 
-    if (space_id < 0)
+    /* Check for invalid ID */
+    if(space_id < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid space_id (ID cannot be a negative number)")
  
-    if (H5S_ALL == space_id) {
-        /* No special dataspace struct for H5S_ALL */
+    /* No special dataspace struct for H5S_ALL */
+    if(H5S_ALL == space_id)
         *space = NULL;
-    }
     else {
         /* Get the dataspace pointer */
-        if (NULL == (*space = (const H5S_t *)H5I_object_verify(space_id, H5I_DATASPACE)))
+        if(NULL == (*space = (const H5S_t *)H5I_object_verify(space_id, H5I_DATASPACE)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "space_id is not a dataspace ID")
 
         /* Check for valid selection */
-        if (H5S_SELECT_VALID(*space) != TRUE)
+        if(H5S_SELECT_VALID(*space) != TRUE)
             HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "selection + offset not within extent")
-    }
+    } /* end else */
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-
 } /* end H5S_get_validated_dataspace() */
 
 
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index ed3fa45..88c570d 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -278,11 +278,8 @@ H5S__hyper_print_diminfo(FILE *f, const H5S_t *space)
 static herr_t
 H5S__hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space)
 {
-    const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
-    H5S_hyper_span_info_t *spans;   /* Pointer to hyperslab span info node */
     unsigned rank;                  /* Dataspace's dimension rank */
     unsigned u;                     /* Index variable */
-    int i;                          /* Index variable */
 
     FUNC_ENTER_STATIC_NOERR
 
@@ -298,16 +295,16 @@ H5S__hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space)
     /* Get the rank of the dataspace */
     rank = space->extent.rank;
 
-    /* Set the temporary pointer to the dimension information */
-    tdiminfo = space->select.sel_info.hslab->opt_diminfo;
-
     /* Check for the special case of just one H5Sselect_hyperslab call made */
     if(space->select.sel_info.hslab->diminfo_valid) {
 /* Initialize the information needed for regular hyperslab I/O */
+        const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
         const hsize_t *mem_size;    /* Temporary pointer to dataspace extent's dimension sizes */
-        hsize_t acc;                /* Accumulator for "flattened" dimension's sizes */
         unsigned cont_dim = 0;      /* # of contiguous dimensions */
 
+        /* Set the temporary pointer to the dimension information */
+        tdiminfo = space->select.sel_info.hslab->opt_diminfo;
+
         /* Set the temporary pointer to the dataspace extent's dimension sizes */
         mem_size = space->extent.size;
 
@@ -336,9 +333,11 @@ H5S__hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space)
 
         /* Check if the regular selection can be "flattened" */
         if(cont_dim > 0) {
+            hsize_t acc;                /* Accumulator for "flattened" dimension's sizes */
             unsigned last_dim_flattened = 1;    /* Flag to indicate that the last dimension was flattened */
             unsigned flat_rank = rank-cont_dim; /* Number of dimensions after flattening */
             unsigned curr_dim;                  /* Current dimension */
+            int i;                      /* Index variable */
 
             /* Set the iterator's rank to the contiguous dimensions */
             iter->u.hyp.iter_rank = flat_rank;
@@ -416,6 +415,8 @@ H5S__hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space)
         iter->u.hyp.spans = NULL;
     } /* end if */
     else {
+        H5S_hyper_span_info_t *spans;   /* Pointer to hyperslab span info node */
+
 /* Initialize the information needed for non-regular hyperslab I/O */
         HDassert(space->select.sel_info.hslab->span_lst);
         /* Make a copy of the span tree to iterate over */
@@ -1443,70 +1444,65 @@ H5S__hyper_cmp_spans(const H5S_hyper_span_info_t *span_info1, const H5S_hyper_sp
 
     FUNC_ENTER_STATIC_NOERR
 
-    /* Check for redundant comparison */
+    /* Check for redundant comparison (or both spans being NULL) */
     if(span_info1 == span_info2)
         ret_value = TRUE;
     else {
-        const H5S_hyper_span_t *span1;
-        const H5S_hyper_span_t *span2;
-
-        /* Check for both spans being NULL */
-        if(span_info1 == NULL && span_info2 == NULL)
-            ret_value = TRUE;
+        /* Check for one span being NULL */
+        if(span_info1 == NULL || span_info2 == NULL)
+            ret_value = FALSE;
         else {
-            /* Check for one span being NULL */
-            if(span_info1 == NULL || span_info2 == NULL)
-                ret_value = FALSE;
-            else {
-                /* Get the pointers to the actual lists of spans */
-                span1 = span_info1->head;
-                span2 = span_info2->head;
-
-                /* Sanity checking */
-                HDassert(span1);
-                HDassert(span2);
-
-                /* infinite loop which must be broken out of */
-                while(1) {
-                    /* Check for both spans being NULL */
-                    if(span1 == NULL && span2 == NULL) {
-                        ret_value = TRUE;
+            const H5S_hyper_span_t *span1;
+            const H5S_hyper_span_t *span2;
+
+            /* Get the pointers to the actual lists of spans */
+            span1 = span_info1->head;
+            span2 = span_info2->head;
+
+            /* Sanity checking */
+            HDassert(span1);
+            HDassert(span2);
+
+            /* infinite loop which must be broken out of */
+            while(1) {
+                /* Check for both spans being NULL */
+                if(span1 == NULL && span2 == NULL) {
+                    ret_value = TRUE;
+                    break;
+                } /* end if */
+                else {
+                    /* Check for one span being NULL */
+                    if(span1 == NULL || span2 == NULL) {
+                        ret_value = FALSE;
                         break;
                     } /* end if */
                     else {
-                        /* Check for one span being NULL */
-                        if(span1 == NULL || span2 == NULL) {
+                        /* Check if the actual low & high span information is the same */
+                        if(span1->low != span2->low || span1->high != span2->high) {
                             ret_value = FALSE;
                             break;
                         } /* end if */
                         else {
-                            /* Check if the actual low & high span information is the same */
-                            if(span1->low != span2->low || span1->high != span2->high) {
-                                ret_value = FALSE;
-                                break;
-                            } /* end if */
-                            else {
-                                if(span1->down != NULL || span2 != NULL) {
-                                    if(!H5S__hyper_cmp_spans(span1->down, span2->down)) {
-                                        ret_value = FALSE;
-                                        break;
-                                    } /* end if */
-                                    else {
-                                        /* Keep going... */
-                                    } /* end else */
+                            if(span1->down != NULL || span2 != NULL) {
+                                if(!H5S__hyper_cmp_spans(span1->down, span2->down)) {
+                                    ret_value = FALSE;
+                                    break;
                                 } /* end if */
                                 else {
                                     /* Keep going... */
                                 } /* end else */
+                            } /* end if */
+                            else {
+                                /* Keep going... */
                             } /* end else */
                         } /* end else */
                     } /* end else */
+                } /* end else */
 
-                    /* Advance to the next nodes in the span list */
-                    span1 = span1->next;
-                    span2 = span2->next;
-                } /* end while */
-            } /* end else */
+                /* Advance to the next nodes in the span list */
+                span1 = span1->next;
+                span2 = span2->next;
+            } /* end while */
         } /* end else */
     } /* end else */
 
@@ -2368,17 +2364,17 @@ H5S__hyper_deserialize(H5S_t *space, uint32_t H5_ATTR_UNUSED version, uint8_t fl
         hsize_t *tstart;	/* Temporary hyperslab pointers */
         hsize_t *tend;		/* Temporary hyperslab pointers */
         hsize_t *tblock;	/* Temporary hyperslab pointers */
-        size_t num_elem;      	/* Number of elements in selection */
+        size_t block_count;     /* Number of blocks in selection */
         unsigned v;            	/* Local counting variable */
 
-        /* Decode the number of points */
-        UINT32DECODE(pp, num_elem);
+        /* Decode the number of blocks */
+        UINT32DECODE(pp, block_count);
 
         /* Set the count & stride for all blocks */
         stride = count = H5S_hyper_ones_g;
 
         /* Retrieve the coordinates from the buffer */
-        for(u = 0; u < num_elem; u++) {
+        for(u = 0; u < block_count; u++) {
             /* Decode the starting points */
             for(tstart = start, v = 0; v < rank; v++, tstart++)
                 UINT32DECODE(pp, *tstart);
@@ -3283,10 +3279,9 @@ H5S__hyper_is_single(const H5S_t *space)
          */
 
         /* Check for a single block */
-        for(u = 0; u < space->extent.rank; u++) {
+        for(u = 0; u < space->extent.rank; u++)
             if(space->select.sel_info.hslab->opt_diminfo[u].count > 1)
                 HGOTO_DONE(FALSE)
-        } /* end for */
     } /* end if */
     else {
         H5S_hyper_span_info_t *spans;   /* Hyperslab span info node */
@@ -4019,13 +4014,12 @@ done:
  PURPOSE
     Helper routine to detect intersections in span trees
  USAGE
-    htri_t H5S_hyper_intersect_block_helper(spans, start, end)
+    hbool_t H5S__hyper_intersect_block_helper(spans, start, end)
         H5S_hyper_span_info_t *spans;     IN: First span tree to operate with
-        hssize_t *offset;   IN: Selection offset coordinate
         hsize_t *start;    IN: Starting coordinate for block
         hsize_t *end;      IN: Ending coordinate for block
  RETURN
-    Non-negative on success, negative on failure
+    Non-negative (TRUE/FALSE) on success, can't fail
  DESCRIPTION
     Quickly detect intersections between span tree and block
  GLOBAL VARIABLES
@@ -4369,6 +4363,7 @@ static herr_t
 H5S__hyper_project_simple_higher(const H5S_t *base_space, H5S_t *new_space)
 {
     H5S_hyper_span_t *prev_span = NULL; /* Pointer to previous list of spans */
+    unsigned delta_rank;                /* Difference in dataspace ranks */
     unsigned curr_dim;                  /* Current dimension being operated on */
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -4382,7 +4377,8 @@ H5S__hyper_project_simple_higher(const H5S_t *base_space, H5S_t *new_space)
     /* Create nodes until reaching the correct # of dimensions */
     new_space->select.sel_info.hslab->span_lst = NULL;
     curr_dim = 0;
-    while(curr_dim < (new_space->extent.rank - base_space->extent.rank)) {
+    delta_rank = (new_space->extent.rank - base_space->extent.rank);
+    while(curr_dim < delta_rank) {
         H5S_hyper_span_info_t *new_span_info;  /* Pointer to list of spans */
         H5S_hyper_span_t *new_span;     /* Temporary hyperslab span */
 
@@ -4723,11 +4719,11 @@ done:
     "Normalize" a hyperslab selection by adjusting it's coordinates by the
     amount of the selection offset.
  USAGE
-    hbool_t H5S_hyper_normalize_offset(space, old_offset)
+    htri_t H5S_hyper_normalize_offset(space, old_offset)
         H5S_t *space;           IN/OUT: Pointer to dataspace to move
         hssize_t *old_offset;   OUT: Pointer to space to store old offset
  RETURNS
-    TRUE if space has been normalized, FALSE if not
+    TRUE/FALSE for hyperslab selection, FAIL on error
  DESCRIPTION
     Copies the current selection offset into the array provided, then
     inverts the selection offset, subtracts the offset from the hyperslab
@@ -4740,7 +4736,7 @@ done:
 htri_t
 H5S_hyper_normalize_offset(H5S_t *space, hssize_t *old_offset)
 {
-    htri_t ret_value = FALSE;           /* Return value */
+    htri_t ret_value = FALSE;          /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
@@ -5101,10 +5097,10 @@ H5S__hyper_clip_spans(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_s
                     /* Split off upper part of span 'b' at upper span of span 'a' */
 
                     /* Check if there is actually an upper part of span 'b' to split off */
-                    if(span_a->high<span_b->high) {
+                    if(span_a->high < span_b->high) {
                         /* Allocate new span node for upper part of span 'b' */
                         if(NULL == (tmp_span = H5S__hyper_new_span(span_a->high + 1, span_b->high, span_b->down, span_b->next)))
-                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
+                            HGOTO_ERROR(H5E_DATASPACE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
 
                         /* Advance span 'a' */
                         H5S__hyper_recover_span(&recover_a,&span_a,span_a->next);
@@ -5269,12 +5265,12 @@ H5S__hyper_clip_spans(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_s
                     } /* end else */
 
                     /* Check if there is actually an upper part of span 'b' to split off */
-                    if(span_a->high<span_b->high) {
+                    if(span_a->high < span_b->high) {
                         /* Split off upper part of span 'b' at upper span of span 'a' */
 
                         /* Allocate new span node for upper part of spans 'a' */
                         if(NULL == (tmp_span = H5S__hyper_new_span(span_a->high + 1, span_b->high, span_b->down, span_b->next)))
-                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
+                            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate hyperslab span")
 
                         /* And advance span 'a' */
                         H5S__hyper_recover_span(&recover_a,&span_a,span_a->next);
@@ -5294,9 +5290,9 @@ H5S__hyper_clip_spans(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_s
                 /*                AAAAAAAAAA             */
                 /* <-----------------------------------> */
                 /*             BBBBBBBBBB                */
-                else if((span_a->low>=span_b->low && span_a->low<=span_b->high) && span_a->high>span_b->high) {
+                else if((span_a->low >= span_b->low && span_a->low <= span_b->high) && span_a->high > span_b->high) {
                     /* Check if there is actually a lower part of span 'b' to split off */
-                    if(span_a->low>span_b->low) {
+                    if(span_a->low > span_b->low) {
                         /* Split off lower part of span 'b' at lower span of span 'a' */
 
                         /* Merge/add lower part of span 'b' with/to b_not_a list */
@@ -5364,7 +5360,7 @@ H5S__hyper_clip_spans(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_s
 
                     /* Allocate new span node for upper part of span 'a' */
                     if(NULL == (tmp_span = H5S__hyper_new_span(span_b->high + 1, span_a->high, span_a->down, span_a->next)))
-                        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
+                        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate hyperslab span")
 
                     /* Make upper part of span 'a' into new span 'a' */
                     H5S__hyper_recover_span(&recover_a,&span_a,tmp_span);
@@ -5448,12 +5444,6 @@ static H5S_hyper_span_info_t *
 H5S__hyper_merge_spans_helper(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_spans)
 {
     H5S_hyper_span_info_t *merged_spans = NULL; /* Pointer to the merged span tree */
-    H5S_hyper_span_info_t *tmp_spans;   /* Pointer to temporary new span tree */
-    H5S_hyper_span_t *tmp_span;         /* Pointer to temporary new span */
-    H5S_hyper_span_t *span_a;           /* Pointer to current span 'a' working on */
-    H5S_hyper_span_t *span_b;           /* Pointer to current span 'b' working on */
-    H5S_hyper_span_t *prev_span_merge;  /* Pointer to previous merged span */
-    hbool_t recover_a, recover_b;         /* Flags to indicate when to recover temporary spans */
     H5S_hyper_span_info_t *ret_value = NULL;    /* Return value */
 
     FUNC_ENTER_STATIC
@@ -5472,6 +5462,11 @@ H5S__hyper_merge_spans_helper(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_inf
         } /* end else */
     } /* end if */
     else {
+        H5S_hyper_span_t *span_a;           /* Pointer to current span 'a' working on */
+        H5S_hyper_span_t *span_b;           /* Pointer to current span 'b' working on */
+        H5S_hyper_span_t *prev_span_merge;  /* Pointer to previous merged span */
+        hbool_t recover_a, recover_b;       /* Flags to indicate when to recover temporary spans */
+
         /* Get the pointers to the 'a' and 'b' span lists */
         span_a = a_spans->head;
         span_b = b_spans->head;
@@ -5484,6 +5479,9 @@ H5S__hyper_merge_spans_helper(H5S_hyper_span_info_t *a_spans, H5S_hyper_span_inf
 
         /* Work through the list of spans in the new list */
         while(span_a != NULL && span_b != NULL) {
+            H5S_hyper_span_info_t *tmp_spans;   /* Pointer to temporary new span tree */
+            H5S_hyper_span_t *tmp_span;         /* Pointer to temporary new span */
+
             /* Check if the 'a' span is completely before 'b' span */
             /*    AAAAAAA                            */
             /* <-----------------------------------> */
@@ -5766,7 +5764,7 @@ done:
 static herr_t
 H5S__hyper_merge_spans(H5S_t *space, H5S_hyper_span_info_t *new_spans, hbool_t can_own)
 {
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
+    FUNC_ENTER_STATIC_NOERR
 
     /* Check args */
     HDassert(space);
@@ -9317,21 +9315,17 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
         
     /* Assert that src_space and src_intersect_space have same extent and there
      * are no point selections */
-    HDassert(H5S_GET_EXTENT_NDIMS(src_space)
-            == H5S_GET_EXTENT_NDIMS(src_intersect_space));
+    HDassert(H5S_GET_EXTENT_NDIMS(src_space) == H5S_GET_EXTENT_NDIMS(src_intersect_space));
     HDassert(!HDmemcmp(src_space->extent.size, src_intersect_space->extent.size,
-            (size_t)H5S_GET_EXTENT_NDIMS(src_space)
-            * sizeof(src_space->extent.size[0])));
+            (size_t)H5S_GET_EXTENT_NDIMS(src_space) * sizeof(src_space->extent.size[0])));
     HDassert(H5S_GET_SELECT_TYPE(src_space) != H5S_SEL_POINTS);
     HDassert(H5S_GET_SELECT_TYPE(dst_space) != H5S_SEL_POINTS);
     HDassert(H5S_GET_SELECT_TYPE(src_intersect_space) != H5S_SEL_POINTS);
 
     /* Initialize prev_space, curr_span_tree, and curr_span_up_dim */
-    for(i = 0; i < H5S_MAX_RANK; i++) {
-        curr_span_tree[i] = NULL;
-        prev_span[i] = NULL;
-        curr_span_up_dim[i] = (hsize_t)0;
-    } /* end for */
+    HDmemset(curr_span_tree, 0, sizeof(curr_span_tree));
+    HDmemset(prev_span, 0, sizeof(prev_span));
+    HDmemset(curr_span_up_dim, 0, sizeof(curr_span_up_dim));
 
     /* Save rank of projected space */
     proj_rank = proj_space->extent.rank;
@@ -9343,8 +9337,7 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
     sis_nelem = (size_t)H5S_GET_SELECT_NPOINTS(src_intersect_space);
     HDassert(ss_nelem == ds_nelem);
 
-    /* Calculate proj_down_dims (note loop relies on unsigned i wrapping around)
-     */
+    /* Calculate proj_down_dims */
     if(H5VM_array_down(proj_rank, proj_space->extent.size, proj_down_dims) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSET, FAIL, "can't compute 'down' chunk size value")
 
@@ -9358,7 +9351,7 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
 
     /* Allocate space for the hyperslab selection information (note this sets
      * diminfo_valid to FALSE, diminfo arrays to 0, and span list to NULL) */
-    if((proj_space->select.sel_info.hslab = H5FL_CALLOC(H5S_hyper_sel_t)) == NULL)
+    if(NULL == (proj_space->select.sel_info.hslab = H5FL_CALLOC(H5S_hyper_sel_t)))
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate hyperslab info")
 
     /* Set selection type */
@@ -9367,9 +9360,9 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
     /* Set unlim_dim */
     proj_space->select.sel_info.hslab->unlim_dim = -1;
 
-    /* Allocate the source space iterator */
+    /* Allocate the source selection iterator */
     if(NULL == (ss_iter = H5FL_MALLOC(H5S_sel_iter_t)))
-        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate source space iterator")
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate source selection iterator")
 
     /* Initialize source space iterator */
     if(H5S_select_iter_init(ss_iter, src_space, (size_t)1) < 0)
@@ -9382,9 +9375,9 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
     ss_nelem -= nelem;
     HDassert(ss_nseq > 0);
 
-    /* Allocate the destination space iterator */
+    /* Allocate the destination selection iterator */
     if(NULL == (ds_iter = H5FL_MALLOC(H5S_sel_iter_t)))
-        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate destination space iterator")
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate destination selection iterator")
 
     /* Initialize destination space iterator */
     if(H5S_select_iter_init(ds_iter, dst_space, (size_t)1) < 0)
@@ -9443,9 +9436,8 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
 
             /* Reset advance_ss */
             advance_ss = FALSE;
-        } /* end if */
-        if(advance_sis
-                || (sis_off[sis_i] + sis_len[sis_i] <= ss_off[ss_i])) {
+        } /* end while */
+        if(advance_sis || (sis_off[sis_i] + sis_len[sis_i] <= ss_off[ss_i])) {
             do {
                 /* Either we finished the current source intersect sequence or
                  * the sequences do not intersect.  Advance source intersect
@@ -9524,8 +9516,7 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
                 HDassert(ds_sel_off <= int_sel_off);
                 proj_off = ds_off[ds_i] + int_sel_off - ds_sel_off;
                 proj_len = proj_len_rem = (size_t)MIN(int_len,
-                        (size_t)(ds_sel_off + (hsize_t)ds_len[ds_i]
-                        - int_sel_off));
+                        (size_t)(ds_sel_off + (hsize_t)ds_len[ds_i] - int_sel_off));
 
                 /* Add to span tree */
                 while(proj_len_rem > (size_t)0) {
@@ -9565,7 +9556,7 @@ H5S__hyper_project_intersection(const H5S_t *src_space, const H5S_t *dst_space,
                             (size_t)(proj_space->extent.size[proj_rank - 1]
                             - low));
                     HDassert(proj_len_rem >= span_len);
-                    high = low + (hsize_t)span_len - (hsize_t)1;
+                    high = (low + (hsize_t)span_len) - (hsize_t)1;
 
                     /* Append span in lowest dimension */
                     if(H5S__hyper_append_span(&prev_span[proj_rank - 1], &curr_span_tree[proj_rank - 1], low, high, NULL, NULL) < 0)
@@ -9791,11 +9782,11 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-void
+static void
 H5S__hyper_get_clip_diminfo(hsize_t start, hsize_t stride, hsize_t *count,
     hsize_t *block, hsize_t clip_size)
 {
-    FUNC_ENTER_PACKAGE_NOERR
+    FUNC_ENTER_STATIC_NOERR
 
     /* Check for selection outside clip size */
     if(start >= clip_size) {
@@ -9819,7 +9810,7 @@ H5S__hyper_get_clip_diminfo(hsize_t start, hsize_t stride, hsize_t *count,
     } /* end else */
 
     FUNC_LEAVE_NOAPI_VOID
-} /* end H5S_hyper_get_clip_diminfo() */
+} /* end H5S__hyper_get_clip_diminfo() */
 
 
 /*--------------------------------------------------------------------------
@@ -9836,8 +9827,7 @@ H5S__hyper_get_clip_diminfo(hsize_t start, hsize_t stride, hsize_t *count,
     Non-negative on success/Negative on failure.
  DESCRIPTION
     This function changes the unlimited selection into a limited selection
-    with the extent of the formerly unlimited dimension specified by
-    * clip_size.
+    with the extent of the formerly unlimited dimension specified by clip_size.
  GLOBAL VARIABLES
  COMMENTS, BUGS, ASSUMPTIONS
     Note this function does not take the offset into account.
@@ -9892,8 +9882,7 @@ H5S_hyper_clip_unlim(H5S_t *space, hsize_t clip_size)
     } /* end if */
     else {
         /* Calculate number of elements */
-        space->select.num_elem = diminfo->count * diminfo->block
-                * hslab->num_elem_non_unlim;
+        space->select.num_elem = diminfo->count * diminfo->block * hslab->num_elem_non_unlim;
 
         /* Check if last block is partial.  If superset is set, just keep the
          * last block complete to speed computation. */
@@ -9924,8 +9913,7 @@ H5S_hyper_clip_unlim(H5S_t *space, hsize_t clip_size)
             /* Indicate that the regular dimensions are no longer valid */
             hslab->diminfo_valid = FALSE;
 
-            /* "And" selection with calculated block to perform clip operation
-             */
+            /* "And" selection with calculated block to perform clip operation */
             if(H5S__generate_hyperslab(space, H5S_SELECT_AND, start, H5S_hyper_ones_g, H5S_hyper_ones_g, block) < 0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't generate hyperslabs")
         } /* end if */
@@ -10369,7 +10357,7 @@ done:
 
 /*--------------------------------------------------------------------------
  NAME
-    H5Sgetregular_hyperslab
+    H5Sget_regular_hyperslab
  PURPOSE
     Retrieve a regular hyperslab selection
  USAGE
diff --git a/src/H5Spkg.h b/src/H5Spkg.h
index d895f40..9ad97dc 100644
--- a/src/H5Spkg.h
+++ b/src/H5Spkg.h
@@ -124,7 +124,7 @@ typedef struct {
          * information. */
     int unlim_dim;                      /* Dimension where selection is unlimited, or -1 if none */
     hsize_t num_elem_non_unlim;         /* # of elements in a "slice" excluding the unlimited dimension */
-    H5S_hyper_span_info_t *span_lst;    /* List of hyperslab span information */
+    H5S_hyper_span_info_t *span_lst;    /* List of hyperslab span information of all dimensions */
 } H5S_hyper_sel_t;
 
 /* Selection information methods */
@@ -275,8 +275,7 @@ H5_DLL herr_t H5S_extent_copy_real(H5S_extent_t *dst, const H5S_extent_t *src,
 
 /* Operations on selections */
 H5_DLL herr_t H5S__hyper_project_intersection(const H5S_t *src_space,
-    const H5S_t *dst_space, const H5S_t *src_intersect_space,
-    H5S_t *proj_space);
+    const H5S_t *dst_space, const H5S_t *src_intersect_space, H5S_t *proj_space);
 H5_DLL herr_t H5S__hyper_subtract(H5S_t *space, H5S_t *subtract_space);
 
 /* Testing functions */
diff --git a/src/H5Spoint.c b/src/H5Spoint.c
index 9924920..aea7d5c 100644
--- a/src/H5Spoint.c
+++ b/src/H5Spoint.c
@@ -775,7 +775,6 @@ done:
 static hssize_t
 H5S_point_serial_size (const H5S_t *space)
 {
-    H5S_pnt_node_t *curr;       /* Point information nodes */
     hssize_t ret_value = -1;    /* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT_NOERR
@@ -789,12 +788,8 @@ H5S_point_serial_size (const H5S_t *space)
     ret_value = 24;
 
     /* Count points in selection */
-    curr=space->select.sel_info.pnt_lst->head;
-    while(curr!=NULL) {
-        /* Add 4 bytes times the rank for each element selected */
-        ret_value+=4*space->extent.rank;
-        curr=curr->next;
-    } /* end while */
+    /* (Add 4 bytes times the rank for each element selected) */
+    ret_value += (4 * space->extent.rank) * (hssize_t)H5S_GET_SELECT_NPOINTS(space);
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5S_point_serial_size() */
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index ea10517..dd656b1 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -1515,14 +1515,20 @@ H5S_select_iterate(void *buf, const H5T_t *type, const H5S_t *space,
                         /* Make the application callback */
                         user_ret = (op->u.app_op.op)(loc, op->u.app_op.type_id, ndims, coords, op_data);
                     break;
+
                     case H5S_SEL_ITER_OP_LIB:
                         /* Call the library's callback */
                         user_ret = (op->u.lib_op)(loc, type, ndims, coords, op_data);
                     break;
+
                     default:
                         HGOTO_ERROR(H5E_DATASPACE, H5E_UNSUPPORTED, FAIL, "unsupported op type")
                 } /* end switch */
 
+                /* Check for error return from iterator */
+                if(user_ret < 0)
+                    HERROR(H5E_DATASPACE, H5E_CANTNEXT, "iteration operator failed");
+
                 /* Increment offset in dataspace */
                 curr_off += elmt_size;
 
@@ -1709,10 +1715,6 @@ H5S_select_shape_same(const H5S_t *space1, const H5S_t *space2)
         HDassert(space_a_rank >= space_b_rank);
         HDassert(space_b_rank > 0);
 
-        /* Check for different number of elements selected */
-        if(H5S_GET_SELECT_NPOINTS(space_a) != H5S_GET_SELECT_NPOINTS(space_b))
-            HGOTO_DONE(FALSE)
-
         /* Check for "easy" cases before getting into generalized block iteration code */
         if((H5S_GET_SELECT_TYPE(space_a) == H5S_SEL_ALL) && (H5S_GET_SELECT_TYPE(space_b) == H5S_SEL_ALL)) {
             hsize_t dims1[H5O_LAYOUT_NDIMS];    /* End point of selection block in dataspace #1 */
diff --git a/src/H5T.c b/src/H5T.c
index 01ace87..9544488 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -295,6 +295,7 @@ static htri_t H5T__compiler_conv(H5T_t *src, H5T_t *dst);
 static herr_t H5T__set_size(H5T_t *dt, size_t size);
 static herr_t H5T__close_cb(H5T_t *dt);
 static H5T_path_t *H5T__path_find_real(const H5T_t *src, const H5T_t *dst, const char *name, H5T_conv_func_t *conv);
+static hbool_t H5T__detect_reg_ref(const H5T_t *dt);
 
 
 /*****************************/
@@ -5506,6 +5507,111 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:   H5T_detect_reg_ref
+ *
+ * Purpose:    Check whether a datatype contains (or is) a region reference
+ *             datatype.
+ *
+ * Return:      TRUE (1) or FALSE (0) on success
+ *		(Can't fail)
+ *
+ * Programmer:  Quincey Koziol
+ *              Saturday, January 5, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+static hbool_t
+H5T__detect_reg_ref(const H5T_t *dt)
+{
+    unsigned    u;                      /* Local index variable */
+    hbool_t     ret_value = FALSE;      /* Return value */
+
+    FUNC_ENTER_STATIC_NOERR
+
+    /* Sanity checks */
+    HDassert(dt);
+
+    /* Check if this datatype is a region reference */
+    if(H5T_REFERENCE == dt->shared->type && H5R_DATASET_REGION == dt->shared->u.atomic.u.r.rtype)
+        HGOTO_DONE(TRUE);
+
+    /* Check for types that might have the correct type as a component */
+    switch(dt->shared->type) {
+        case H5T_COMPOUND:
+            /* Iterate over all the compound datatype's fields */
+            for(u = 0; u < dt->shared->u.compnd.nmembs; u++)
+                /* Recurse on field's datatype */
+                if(H5T__detect_reg_ref(dt->shared->u.compnd.memb[u].type))
+                    HGOTO_DONE(TRUE);
+            break;
+
+        case H5T_ARRAY:
+        case H5T_VLEN:
+        case H5T_ENUM:
+            HGOTO_DONE(H5T__detect_reg_ref(dt->shared->parent));
+            break;
+
+        case H5T_NO_CLASS:
+        case H5T_INTEGER:
+        case H5T_FLOAT:
+        case H5T_TIME:
+        case H5T_STRING:
+        case H5T_BITFIELD:
+        case H5T_OPAQUE:
+        case H5T_REFERENCE:
+        case H5T_NCLASSES:
+        default:
+            break;
+    } /* end if */
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T__detect_reg_ref() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5T_is_vl_storage
+ *
+ * Purpose:     Check if a datatype will be stored in a variable-length form.
+ *
+ * Notes:       Currently, only variable-length string & sequences and region
+ *              references are stored in a variable-length form.
+ *
+ * Return:
+ *  One of two values on success:
+ *      TRUE - If the datatype will be stored in a variable-length form
+ *      FALSE - If the datatype will NOT be stored in a variable-length form
+ *  <0 is returned on failure
+ *
+ * Programmer:  Quincey Koziol
+ *              Saturday, January 5, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5T_is_vl_storage(const H5T_t *dt)
+{
+    htri_t ret_value = FALSE;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(dt);
+
+    /* VL and region reference datatypes are stored in variable-length form */
+    if(H5T_detect_class(dt, H5T_VLEN, FALSE))
+        ret_value = TRUE;
+    else if(H5T_detect_class(dt, H5T_REFERENCE, FALSE))
+        ret_value = H5T__detect_reg_ref(dt);
+    else
+        ret_value = FALSE;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5T_is_vl_storage() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5T_upgrade_version_cb
  *
  * Purpose:     H5T__visit callback to Upgrade the version of a datatype
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index 6b6446f..3dcbb2c 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -145,6 +145,7 @@ H5_DLL H5T_t *H5T_get_actual_type(H5T_t *dt);
 H5_DLL herr_t H5T_save_refresh_state(hid_t tid, struct H5O_shared_t *cached_H5O_shared);
 H5_DLL herr_t H5T_restore_refresh_state(hid_t tid, struct H5O_shared_t *cached_H5O_shared);
 H5_DLL hbool_t H5T_already_vol_managed(const H5T_t *dt);
+H5_DLL htri_t H5T_is_vl_storage(const H5T_t *dt);
 
 /* Reference specific functions */
 H5_DLL H5R_type_t H5T_get_ref_type(const H5T_t *dt);
diff --git a/src/H5VL.c b/src/H5VL.c
index 88d3d70..37ad187 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -517,3 +517,73 @@ done:
     FUNC_LEAVE_API(ret_value)
 } /* H5VLcmp_connector_cls() */
 
+
+/*---------------------------------------------------------------------------
+ * Function:    H5VLwrap_register
+ *
+ * Purpose:     Wrap an internal object with a "wrap context" and register an
+ *		hid_t for the resulting object.
+ *
+ * Note:	This routine is mainly targeted toward wrapping objects for
+ *		iteration routine callbacks (i.e. the callbacks from H5Aiterate*,
+ *		H5Literate* / H5Lvisit*, and H5Ovisit* ).
+ *
+ * Return:      Success:    Non-negative hid_t for the object.
+ *              Failure:    Negative (H5I_INVALID_HID)
+ *
+ *---------------------------------------------------------------------------
+ */
+hid_t
+H5VLwrap_register(void *obj, H5I_type_t type)
+{
+    hid_t ret_value;            /* Return value */
+
+    /* Use FUNC_ENTER_API_NOINIT here, so the API context doesn't get reset */
+    FUNC_ENTER_API_NOINIT
+    H5TRACE2("i", "*xIt", obj, type);
+
+    /* Check args */
+    if(type <= H5I_BADID || type >= H5I_NTYPES)
+        HGOTO_ERROR(H5E_VOL, H5E_BADRANGE, H5I_INVALID_HID, "invalid type number")
+    if(NULL == obj)
+        HGOTO_ERROR(H5E_VOL, H5E_BADVALUE, H5I_INVALID_HID, "obj is NULL")
+
+    /* Wrap the object and register an ID for it */
+    if((ret_value = H5VL_wrap_register(type, obj, TRUE)) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to wrap object")
+
+done:
+    FUNC_LEAVE_API_NOINIT(ret_value)
+} /* H5VLwrap_register() */
+
+
+/*---------------------------------------------------------------------------
+ * Function:    H5VLobject
+ *
+ * Purpose:     Retrieve the object pointer associated with an hid_t for a.
+ *		VOL object.
+ *
+ * Note:	This routine is mainly targeted toward unwrapping objects for
+ *		testing.
+ *
+ * Return:      Success:    Object pointer
+ *              Failure:    NULL
+ *
+ *---------------------------------------------------------------------------
+ */
+void *
+H5VLobject(hid_t id)
+{
+    void *ret_value;            /* Return value */
+
+    FUNC_ENTER_API(NULL)
+    H5TRACE1("*x", "i", id);
+
+    /* Retrieve the object pointer for the ID */
+    if(NULL == (ret_value = H5VL_object(id)))
+        HGOTO_ERROR(H5E_VOL, H5E_CANTGET, NULL, "unable to retrieve object")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* H5VLobject() */
+
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 8695a80..bdb2908 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -879,9 +879,11 @@ done:
  *
  * Purpose:     Compare VOL class for a connector
  *
- * Return:      Positive if VALUE1 is greater than VALUE2, negative if
- *              VALUE2 is greater than VALUE1 and zero if VALUE1 and
- *              VALUE2 are equal (like strcmp).
+ * Note:        Sets *cmp_value positive if VALUE1 is greater than VALUE2,
+ *		negative if VALUE2 is greater than VALUE1, and zero if VALUE1
+ *              and VALUE2 are equal (like strcmp).
+ *
+ * Return:      SUCCEED / FAIL
  *
  *-------------------------------------------------------------------------
  */
diff --git a/src/H5VLpassthru.c b/src/H5VLpassthru.c
index 8b83e2e..13d8d8e 100644
--- a/src/H5VLpassthru.c
+++ b/src/H5VLpassthru.c
@@ -26,6 +26,7 @@
 /* Header files needed */
 /* (Public HDF5 and standard C / POSIX only) */
 #include <assert.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -171,7 +172,7 @@ static const H5VL_class_t H5VL_pass_through_g = {
     0,                                              /* capability flags */
     H5VL_pass_through_init,                         /* initialize   */
     H5VL_pass_through_term,                         /* terminate    */
-    sizeof(H5VL_pass_through_t),                    /* info size    */
+    sizeof(H5VL_pass_through_info_t),               /* info size    */
     H5VL_pass_through_info_copy,                    /* info copy    */
     H5VL_pass_through_info_cmp,                     /* info compare */
     H5VL_pass_through_info_free,                    /* info free    */
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index 5de36c8..dd1ed54 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -433,6 +433,8 @@ H5_DLL herr_t H5VLunregister_connector(hid_t connector_id);
 
 /* Helper routines for VOL connector authors */
 H5_DLL herr_t H5VLcmp_connector_cls(int *cmp, hid_t connector_id1, hid_t connector_id2);
+H5_DLL hid_t H5VLwrap_register(void *obj, H5I_type_t type);
+H5_DLL void *H5VLobject(hid_t obj_id);
 
 
 /* Public wrappers for generic callbacks */