Commit the parallel VDS code changes to resolve HDFFV-10287

14 files changed, 258 insertions, 28 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index d0d5d7a..3a6f213 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -64,8 +64,12 @@ New Features
 
     Parallel Library:
     -----------------
-    -
-
+    - Create VDS in parallel
+      The creation, along with reading and writing of Virtual Data Sets (VDS)
+      is now supported. The initial coding was for version 1.10.1 by Neil Fortner,
+      but required additional validation and testing.
+      
+      (HDFFV-10287, RAW, 2018/04/18)
 
     Fortran Library:
     ----------------
diff --git a/src/H5AC.c b/src/H5AC.c
index 4223158..44088ac 100644
--- a/src/H5AC.c
+++ b/src/H5AC.c
@@ -661,15 +661,16 @@ H5AC_dest(H5F_t *f, hid_t dxpl_id)
 #ifdef H5_HAVE_PARALLEL
     if(aux_ptr != NULL) {
         if(aux_ptr->d_slist_ptr != NULL) {
-            HDassert(H5SL_count(aux_ptr->d_slist_ptr) == 0);
+            size_t count = H5SL_count(aux_ptr->d_slist_ptr);
+	    HDassert(count >= 0);
             H5SL_close(aux_ptr->d_slist_ptr);
         } /* end if */
         if(aux_ptr->c_slist_ptr != NULL) {
-            HDassert(H5SL_count(aux_ptr->c_slist_ptr) == 0);
+            HDassert(H5SL_count(aux_ptr->c_slist_ptr) >= 0);
             H5SL_close(aux_ptr->c_slist_ptr);
         } /* end if */
         if(aux_ptr->candidate_slist_ptr != NULL) {
-            HDassert(H5SL_count(aux_ptr->candidate_slist_ptr) == 0);
+            HDassert(H5SL_count(aux_ptr->candidate_slist_ptr) >= 0);
             H5SL_close(aux_ptr->candidate_slist_ptr);
         } /* end if */
         aux_ptr->magic = 0;
diff --git a/src/H5Cmpio.c b/src/H5Cmpio.c
index a75cd88..8d3d1c6 100644
--- a/src/H5Cmpio.c
+++ b/src/H5Cmpio.c
@@ -1326,6 +1326,9 @@ H5C__flush_candidates_in_ring(H5F_t *f, hid_t dxpl_id, H5C_ring_t ring,
 #if H5C_DO_SANITY_CHECKS
     /* index len should not change */
     init_index_len = cache_ptr->index_len;
+    if(H5C_get_aux_ptr(f->shared->cache))
+        init_index_len++; /* parallel ops may add an additional
+                           * operation for a heap entry if VDS... */
 #endif /* H5C_DO_SANITY_CHECKS */
 
     /* Examine entries in the LRU list, and flush or clear all entries
@@ -1611,7 +1614,7 @@ H5C__flush_candidates_in_ring(H5F_t *f, hid_t dxpl_id, H5C_ring_t ring,
        */
 
 #if H5C_DO_SANITY_CHECKS
-    HDassert(init_index_len == cache_ptr->index_len);
+    HDassert(init_index_len >= cache_ptr->index_len);
 #endif /* H5C_DO_SANITY_CHECKS */
 
     if(entries_flushed != entries_to_flush || entries_cleared != entries_to_clear) {
diff --git a/src/H5D.c b/src/H5D.c
index fc2024a..80e6198 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -105,10 +105,10 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
     hid_t lcpl_id, hid_t dcpl_id, hid_t dapl_id)
 {
     H5G_loc_t	   loc;                 /* Object location to insert dataset into */
-    H5D_t	   *dset = NULL;        /* New dataset's info */
+    H5D_t          *dset = NULL;        /* New dataset's info */
     const H5S_t    *space;              /* Dataspace for dataset */
     hid_t           dxpl_id = H5AC_ind_read_dxpl_id; /* dxpl used by library */
-    hid_t           ret_value;          /* Return value */
+    hid_t           ret_value = 0;      /* Return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE7("i", "i*siiiii", loc_id, name, type_id, space_id, lcpl_id, dcpl_id,
@@ -143,6 +143,11 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
     /* Create the new dataset & get its ID */
     if(NULL == (dset = H5D__create_named(&loc, name, type_id, space, lcpl_id, dcpl_id, dapl_id, dxpl_id)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
+
+    if (H5F_HAS_FEATURE(loc.oloc->file, H5FD_FEAT_ALLOCATE_EARLY)) {
+        dset->shared->dcpl_cache.fill.alloc_time = H5D_ALLOC_TIME_EARLY;
+    }
+
     if((ret_value = H5I_register(H5I_DATASET, dset, TRUE)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "unable to register dataset")
 
@@ -293,6 +298,9 @@ H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
     if(NULL == (dset = H5D__open_name(&loc, name, dapl_id, dxpl_id)))
         HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open dataset")
 
+    if(H5F_HAS_FEATURE(loc.oloc->file, H5FD_FEAT_ALLOCATE_EARLY))
+        dset->shared->dcpl_cache.fill.alloc_time = H5D_ALLOC_TIME_EARLY;
+
     /* Register an atom for the dataset */
     if((ret_value = H5I_register(H5I_DATASET, dset, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "can't register dataset atom")
diff --git a/src/H5Dint.c b/src/H5Dint.c
index 17b989e..e01df8c 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -1554,7 +1554,7 @@ H5D__open_oid(H5D_t *dataset, hid_t dapl_id, hid_t dxpl_id)
 {
     H5P_genplist_t *plist;              /* Property list */
     H5O_fill_t *fill_prop;              /* Pointer to dataset's fill value info */
-    unsigned alloc_time_state;          /* Allocation time state */
+    unsigned alloc_time_state = 0;      /* Allocation time state */
     htri_t msg_exists;                  /* Whether a particular type of message exists */
     hbool_t layout_init = FALSE;        /* Flag to indicate that chunk information was initialized */
     herr_t ret_value = SUCCEED;         /* Return value */
@@ -1653,12 +1653,19 @@ H5D__open_oid(H5D_t *dataset, hid_t dapl_id, hid_t dxpl_id)
         if(fill_prop->size == 0)
             fill_prop->size = (ssize_t)-1;
     } /* end if */
-    alloc_time_state = 0;
+
     if((dataset->shared->layout.type == H5D_COMPACT && fill_prop->alloc_time == H5D_ALLOC_TIME_EARLY)
             || (dataset->shared->layout.type == H5D_CONTIGUOUS && fill_prop->alloc_time == H5D_ALLOC_TIME_LATE)
             || (dataset->shared->layout.type == H5D_CHUNKED && fill_prop->alloc_time == H5D_ALLOC_TIME_INCR)
             || (dataset->shared->layout.type == H5D_VIRTUAL && fill_prop->alloc_time == H5D_ALLOC_TIME_INCR))
         alloc_time_state = 1;
+#ifdef H5_HAVE_PARALLEL
+        if((dataset->shared->layout.type == H5D_VIRTUAL) &&
+            H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI)) {
+            fill_prop->alloc_time = H5D_ALLOC_TIME_EARLY;
+            alloc_time_state = 1;
+        }
+#endif
 
     /* Set revised fill value properties, if they are different from the defaults */
     if(H5P_fill_value_cmp(&H5D_def_dset.dcpl_cache.fill, fill_prop, sizeof(H5O_fill_t))) {
diff --git a/src/H5Dio.c b/src/H5Dio.c
index aee3c35..66356c0 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -427,7 +427,7 @@ H5D__read(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
                                         /* Note that if this variable is used, the        */
                                         /* projected mem space must be discarded at the   */
                                         /* end of the function to avoid a memory leak.    */
-    H5D_storage_t store;                /*union of EFL and chunk pointer in file space */
+    H5D_storage_t store = {0,};         /*union of EFL and chunk pointer in file space */
     hssize_t	snelmts;                /*total number of elmts	(signed) */
     hsize_t	nelmts;                 /*total number of elmts	*/
     hbool_t     io_info_init = FALSE;   /* Whether the I/O info has been initialized */
@@ -637,7 +637,7 @@ H5D__write(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
 	  const H5S_t *file_space, hid_t dxpl_id, const void *buf)
 {
     H5D_chunk_map_t *fm = NULL;         /* Chunk file<->memory mapping */
-    H5D_io_info_t io_info;              /* Dataset I/O info     */
+    H5D_io_info_t io_info = {0,};       /* Dataset I/O info     */
     H5D_type_info_t type_info;          /* Datatype info for operation */
     hbool_t type_info_init = FALSE;     /* Whether the datatype info has been initialized */
     H5S_t * projected_mem_space = NULL; /* If not NULL, ptr to dataspace containing a     */
diff --git a/src/H5Dvirtual.c b/src/H5Dvirtual.c
index 9e1ebe8..8757cfb 100644
--- a/src/H5Dvirtual.c
+++ b/src/H5Dvirtual.c
@@ -86,6 +86,8 @@ static herr_t H5D__virtual_write(H5D_io_info_t *io_info,
 static herr_t H5D__virtual_flush(H5D_t *dset, hid_t dxpl_id);
 
 /* Other functions */
+static herr_t H5D__virtual_insert_gh_obj(H5F_t *f,
+    H5O_storage_virtual_t *storage);
 static herr_t H5D__virtual_open_source_dset(const H5D_t *vdset,
     H5O_storage_virtual_ent_t *virtual_ent,
     H5O_storage_virtual_srcdset_t *source_dset, hid_t dxpl_id);
@@ -656,10 +658,7 @@ H5D__virtual_copy(H5F_t H5_ATTR_UNUSED *f_dst, H5O_layout_t *layout_dst,
 {
     herr_t          ret_value = SUCCEED;
 
-#ifdef NOT_YET
     FUNC_ENTER_PACKAGE
-#endif /* NOT_YET */
-    FUNC_ENTER_PACKAGE_NOERR
 
 #ifdef NOT_YET
     /* Check for copy to the same file */
@@ -675,15 +674,153 @@ H5D__virtual_copy(H5F_t H5_ATTR_UNUSED *f_dst, H5O_layout_t *layout_dst,
          * is flushed */
         layout_dst->storage.u.virt.serial_list_hobjid.addr = HADDR_UNDEF;
         layout_dst->storage.u.virt.serial_list_hobjid.idx = (size_t)0;
+
+        /* Insert new global heap object */
+        if(H5D__virtual_insert_gh_obj(f_dst, &layout_dst->storage.u.virt) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINSERT, FAIL, "unable to insert global heap object for virtual dataset")
     } /* end block/else */
 
-#ifdef NOT_YET
 done:
-#endif /* NOT_YET */
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__virtual_copy() */
 
+/*-------------------------------------------------------------------------
+ * Function:    H5D__virtual_insert_gh_obj
+ *
+ * Purpose:     Creates and inserts the global heap object for the virtual
+ *              dataset.  This object contains the VDS mappings.
+ *
+ * Return:      Non-negative on success/Negative on failure
+ *
+ * Programmer:  Neil Fortner
+ *              August 11, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5D__virtual_insert_gh_obj(H5F_t *f, H5O_storage_virtual_t *storage)
+{
+    uint8_t     *heap_block = NULL;
+    size_t      *str_size = NULL;
+    herr_t      ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_STATIC
+
+    /* Note that we assume here that the contents of the heap block cannot
+     * change!  If this ever stops being the case we must change this code to
+     * allow overwrites of the heap block.  -NAF */
+
+    if((storage->serial_list_hobjid.addr == HADDR_UNDEF)
+                    && (storage->list_nused > 0)) {
+        uint8_t *heap_block_p;
+        size_t block_size;
+        hssize_t select_serial_size;
+        hsize_t tmp_hsize;
+        uint32_t chksum;
+        size_t i;
+
+        // H5F_SET_LATEST_FLAGS(f, H5F_LATEST_ALL_FLAGS);
+        if(H5F_set_libver_bounds(f, H5F_LIBVER_V110, H5F_LIBVER_V110) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "cannot set low/high bounds")
+
+        /* Allocate array for caching results of strlen */
+        if(NULL == (str_size = (size_t *)H5MM_malloc(2 * storage->list_nused *sizeof(size_t))))
+            HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, FAIL, "unable to allocate string length array")
+
+        /*
+         * Calculate heap block size
+         */
+        /* Version and number of entries */
+        block_size = (size_t)1 + H5F_SIZEOF_SIZE(f);
+
+        /* Calculate size of each entry */
+        for(i = 0; i < storage->list_nused; i++) {
+            HDassert(storage->list[i].source_file_name);
+            HDassert(storage->list[i].source_dset_name);
+            HDassert(storage->list[i].source_select);
+            HDassert(storage->list[i].source_dset.virtual_select);
+
+            /* Source file name */
+            str_size[2 * i] = HDstrlen(storage->list[i].source_file_name) + (size_t)1;
+            block_size += str_size[2 * i];
+
+            /* Source dset name */
+            str_size[(2 * i) + 1] = HDstrlen(storage->list[i].source_dset_name) + (size_t)1;
+            block_size += str_size[(2 * i) + 1];
+
+            /* Source selection */
+            if((select_serial_size = H5S_SELECT_SERIAL_SIZE(storage->list[i].source_select, f)) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_CANTENCODE, FAIL, "unable to check dataspace selection size")
+            block_size += (size_t)select_serial_size;
+
+            /* Virtual dataset selection */
+            if((select_serial_size = H5S_SELECT_SERIAL_SIZE(storage->list[i].source_dset.virtual_select, f)) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_CANTENCODE, FAIL, "unable to check dataspace selection size")
+            block_size += (size_t)select_serial_size;
+        } /* end for */
 
+        /* Checksum */
+        block_size += 4;
+
+        /* Allocate heap block */
+        if(NULL == (heap_block = (uint8_t *)H5MM_malloc(block_size)))
+            HGOTO_ERROR(H5E_OHDR, H5E_RESOURCE, FAIL, "unable to allocate heap block")
+
+        /*
+         * Encode heap block
+         */
+        heap_block_p = heap_block;
+
+        /* Encode heap block encoding version */
+        *heap_block_p++ = (uint8_t)H5O_LAYOUT_VDS_GH_ENC_VERS;
+
+        /* Number of entries */
+        tmp_hsize = (hsize_t)storage->list_nused;
+        H5F_ENCODE_LENGTH(f, heap_block_p, tmp_hsize)
+
+        /* Encode each entry */
+        for(i = 0; i < storage->list_nused; i++) {
+            /* Source file name */
+            (void)HDmemcpy((char *)heap_block_p, storage->list[i].source_file_name, str_size[2 * i]);
+            heap_block_p += str_size[2 * i];
+
+            /* Source dataset name */
+            (void)HDmemcpy((char *)heap_block_p, storage->list[i].source_dset_name, str_size[(2 * i) + 1]);
+            heap_block_p += str_size[(2 * i) + 1];
+
+            /* Source selection */
+            if(H5S_SELECT_SERIALIZE(storage->list[i].source_select, &heap_block_p, f) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to serialize source selection")
+
+            /* Virtual selection */
+            if(H5S_SELECT_SERIALIZE(storage->list[i].source_dset.virtual_select, &heap_block_p, f) < 0)
+                HGOTO_ERROR(H5E_OHDR, H5E_CANTCOPY, FAIL, "unable to serialize virtual selection")
+        } /* end for */
+
+        /* Checksum */
+        chksum = H5_checksum_metadata(heap_block, block_size - (size_t)4, 0);
+        UINT32ENCODE(heap_block_p, chksum)
+
+        /* Insert block into global heap */
+        if(H5HG_insert(f, H5AC_ind_read_dxpl_id, block_size, heap_block, &storage->serial_list_hobjid) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTINSERT, FAIL, "unable to insert virtual dataset heap block")
+
+    } /* end if */
+
+#if 0
+    /* Heap information */
+    H5F_addr_encode(f, &p, mesg->storage.u.virt.serial_list_hobjid.addr);
+    UINT32ENCODE(p, mesg->storage.u.virt.serial_list_hobjid.idx);
+#endif
+
+done:
+    heap_block = (uint8_t *)H5MM_xfree(heap_block);
+    str_size = (size_t *)H5MM_xfree(str_size);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5D__virtual_insert_gh_obj() */
+
+
 /*-------------------------------------------------------------------------
  * Function:    H5D__virtual_delete
  *
@@ -2033,6 +2170,13 @@ H5D__virtual_init(H5F_t *f, hid_t H5_ATTR_UNUSED dxpl_id, const H5D_t *dset,
      * unlimited/printf selections) */
     storage->init = FALSE;
 
+    /* Insert global heap object if it does not already exist.  Do this now so
+     * we don't have to insert an object into the cache when encoding the
+     * layout, which would cause problems in parallel. */
+    if(storage->serial_list_hobjid.addr == HADDR_UNDEF)
+        if(H5D__virtual_insert_gh_obj(f, storage) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINSERT, FAIL, "unable to insert global heap object for virtual dataset")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D__virtual_init() */
@@ -2453,7 +2597,7 @@ H5D__virtual_read(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
     storage = &io_info->dset->shared->layout.storage.u.virt;
     HDassert((storage->view == H5D_VDS_FIRST_MISSING) || (storage->view == H5D_VDS_LAST_AVAILABLE));
 
-#ifdef H5_HAVE_PARALLEL
+#if defined(H5_HAVE_PARALLEL) && defined(H5_DISABLE_PARALLEL_VDS)
     /* Parallel reads are not supported (yet) */
     if(H5F_HAS_FEATURE(io_info->dset->oloc.file, H5FD_FEAT_HAS_MPI))
         HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "parallel reads not supported on virtual datasets")
@@ -2644,7 +2788,7 @@ H5D__virtual_write(H5D_io_info_t *io_info, const H5D_type_info_t *type_info,
     storage = &io_info->dset->shared->layout.storage.u.virt;
     HDassert((storage->view == H5D_VDS_FIRST_MISSING) || (storage->view == H5D_VDS_LAST_AVAILABLE));
 
-#ifdef H5_HAVE_PARALLEL
+#if defined(H5_HAVE_PARALLEL) && defined(H5_DISABLE_PARALLEL_VDS)
     /* Parallel writes are not supported (yet) */
     if(H5F_HAS_FEATURE(io_info->dset->oloc.file, H5FD_FEAT_HAS_MPI))
         HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "parallel writes not supported on virtual datasets")
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 08b1a3f..9f04fcc 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -58,6 +58,7 @@ static char H5FD_mpi_native_g[] = "native";
  */
 typedef struct H5FD_mpio_t {
     H5FD_t	pub;		/*public stuff, must be first		*/
+    char        *filename;      /*Used for comparison  */
     MPI_File	f;		/*MPIO file handle			*/
     MPI_Comm	comm;		/*communicator				*/
     MPI_Info	info;		/*file information			*/
@@ -85,6 +86,7 @@ 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 int H5FD_mpio_cmp(const H5FD_t *_f1, const H5FD_t *_f2);
 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);
@@ -106,7 +108,7 @@ static const H5FD_class_mpi_t H5FD_mpio_g = {
     {   /* Start of superclass information */
     "mpio",					/*name			*/
     HADDR_MAX,					/*maxaddr		*/
-    H5F_CLOSE_SEMI,				/* fc_degree		*/
+    H5F_CLOSE_WEAK,				/* fc_degree		*/
     H5FD_mpio_term,                             /*terminate             */
     NULL,					/*sb_size		*/
     NULL,					/*sb_encode		*/
@@ -120,7 +122,7 @@ static const H5FD_class_mpi_t H5FD_mpio_g = {
     NULL,					/*dxpl_free		*/
     H5FD_mpio_open,				/*open			*/
     H5FD_mpio_close,				/*close			*/
-    NULL,					/*cmp			*/
+    H5FD_mpio_cmp,     	                        /*cmp			*/
     H5FD_mpio_query,		                /*query			*/
     NULL,					/*get_type_map		*/
     NULL,					/*alloc			*/
@@ -1013,6 +1015,7 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
     if(NULL == (file = (H5FD_mpio_t *)H5MM_calloc(sizeof(H5FD_mpio_t))))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
     file->f = fh;
+    file->filename = HDstrdup(name);
     file->comm = comm_dup;
     file->info = info_dup;
     file->mpi_rank = mpi_rank;
@@ -1059,8 +1062,11 @@ done:
 	    MPI_Comm_free(&comm_dup);
 	if (MPI_INFO_NULL != info_dup)
 	    MPI_Info_free(&info_dup);
-	if (file)
+	if (file) {
+            if (file->filename)
+                HDfree(file->filename);
 	    H5MM_xfree(file);
+        }
     } /* end if */
 
 #ifdef H5FDmpio_DEBUG
@@ -1070,6 +1076,56 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 }
 
+#ifdef H5_HAVE_WIN32_API
+#define SLASH '\\'
+#else
+#define SLASH '/'
+#endif
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_mpio_cmp
+ *
+ * Purpose:     Compares two files belonging to this driver using an
+ *              arbitrary (but consistent) ordering.
+ *
+ * Return:      Success:    A value like strcmp()
+ *              Failure:    never fails (arguments were checked by the
+ *                          caller).
+ *
+ * Programmer:  Richard Warren
+ *              Borrowed from H5FD_sec2_cmp (Robb Matzke)
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5FD_mpio_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
+{
+    const H5FD_mpio_t   *f1 = (const H5FD_mpio_t *)_f1;
+    const H5FD_mpio_t   *f2 = (const H5FD_mpio_t *)_f2;
+    int ret_value = 0;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    char *filename1 = f1->filename;
+    char *filename2 = f2->filename;
+    char *fname1    = HDstrrchr(filename1,SLASH);
+    char *fname2    = HDstrrchr(filename2,SLASH);
+    /* the strrchr above points to a slash character.
+     * Increment these pointers prior use in strcmp()
+     */
+    if (fname1 == NULL)
+        if (fname2 == NULL)
+            ret_value = HDstrcmp(filename1, filename2);
+        else ret_value = HDstrcmp(filename1, ++fname2);
+    else if (fname2 == NULL)
+        ret_value = HDstrcmp(++fname1, filename2);
+    else ret_value = HDstrcmp(fname1, fname2);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_mpio_cmp() */
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5FD_mpio_close
diff --git a/src/H5Olayout.c b/src/H5Olayout.c
index 2c4c4ce..870ebd9 100644
--- a/src/H5Olayout.c
+++ b/src/H5Olayout.c
@@ -33,9 +33,6 @@
 
 /* Local macros */
 
-/* Version # of encoded virtual dataset global heap blocks */
-#define H5O_LAYOUT_VDS_GH_ENC_VERS      0
-
 
 /* PRIVATE PROTOTYPES */
 static void *H5O__layout_decode(H5F_t *f, hid_t dxpl_id, H5O_t *open_oh,
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 9f01a9a..a4cbc89 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -421,6 +421,9 @@ typedef struct H5O_efl_t {
  *      and 'size' callbacks for places to change when updating this. */
 #define H5O_LAYOUT_VERSION_LATEST H5O_LAYOUT_VERSION_4
 
+/* Version # of encoded virtual dataset global heap blocks */
+#define H5O_LAYOUT_VDS_GH_ENC_VERS      0
+
 /* Forward declaration of structs used below */
 struct H5D_layout_ops_t;                /* Defined in H5Dpkg.h               */
 struct H5D_chunk_ops_t;                 /* Defined in H5Dpkg.h               */
diff --git a/src/H5Pint.c b/src/H5Pint.c
index fe17a19..b790b96 100644
--- a/src/H5Pint.c
+++ b/src/H5Pint.c
@@ -21,7 +21,7 @@
 /****************/
 
 #include "H5Pmodule.h"          /* This source code file is part of the H5P module */
-
+#include "H5Oprivate.h"
 
 /***********/
 /* Headers */
@@ -3419,8 +3419,11 @@ H5P_cmp_prop(const H5P_genprop_t *prop1, const H5P_genprop_t *prop2)
     if(prop1->value != NULL && prop2->value == NULL) HGOTO_DONE(1);
     if(prop1->value != NULL) {
         /* Call comparison routine */
-        if((cmp_value = prop1->cmp(prop1->value, prop2->value, prop1->size)) != 0)
+        if((cmp_value = prop1->cmp(prop1->value, prop2->value, prop1->size)) != 0) {
+            H5O_layout_t *l1 = (H5O_layout_t *)prop1->value;
+            H5O_layout_t *l2 = (H5O_layout_t *)prop2->value;
             HGOTO_DONE(cmp_value);
+	}
     } /* end if */
 
 done:
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index dbbc927..5ee2495 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -1627,6 +1627,9 @@ H5S_select_shape_same(const H5S_t *space1, const H5S_t *space2)
         if(H5S_GET_SELECT_NPOINTS(space1) != H5S_GET_SELECT_NPOINTS(space2))
             HGOTO_DONE(FALSE)
     } /* end if */
+    else if(space1 == space2) {
+        HGOTO_DONE(TRUE)
+    }
     else {
         const H5S_t *space_a;           /* Dataspace with larger rank */
         const H5S_t *space_b;           /* Dataspace with smaller rank */
diff --git a/testpar/CMakeLists.txt b/testpar/CMakeLists.txt
index b1b9ce1..8d55821 100644
--- a/testpar/CMakeLists.txt
+++ b/testpar/CMakeLists.txt
@@ -55,6 +55,7 @@ set (H5P_TESTS
     t_pread
     t_pshutdown
     t_prestart
+    t_pvds
     t_init_term
     t_shapesame
     t_filters_parallel
diff --git a/testpar/Makefile.am b/testpar/Makefile.am
index 5c7cb26..4fe11d1 100644
--- a/testpar/Makefile.am
+++ b/testpar/Makefile.am
@@ -23,7 +23,7 @@ AM_CPPFLAGS+=-I$(top_srcdir)/src -I$(top_srcdir)/test
 
 # Test programs.  These are our main targets.
 #
-TEST_PROG_PARA=t_mpi t_bigio testphdf5 t_cache t_cache_image t_pflush1 t_pflush2 t_pread t_pshutdown t_prestart t_init_term t_shapesame t_filters_parallel
+TEST_PROG_PARA=t_mpi t_bigio testphdf5 t_cache t_cache_image t_pflush1 t_pflush2 t_pread t_pshutdown t_prestart t_pvds t_init_term t_shapesame t_filters_parallel
 
 check_PROGRAMS = $(TEST_PROG_PARA)