[svn-r7029] Purpose:

    New feature/Bug fix

Description:
    Add new fill time value - H5D_FILL_TIME_IFSET which writes the fill value
to a dataset if the user has defined one, otherwise not writing the fill value
to the dataset.

Platforms tested:
    FreeBSD 4.8 (sleipnir) serial & parallel
    h5committest

7 files changed, 170 insertions, 66 deletions

diff --git a/src/H5.c b/src/H5.c
index 0b92dfd..95dfea9 100644
--- a/src/H5.c
+++ b/src/H5.c
@@ -1632,6 +1632,9 @@ H5_trace (double *returning, const char *func, const char *type, ...)
 		    case H5D_FILL_TIME_NEVER:
 			fprintf (out, "H5D_FILL_TIME_NEVER");
 			break;
+		    case H5D_FILL_TIME_IFSET:
+			fprintf (out, "H5D_FILL_TIME_IFSET");
+			break;
 		    }
 		}
 		break;
diff --git a/src/H5D.c b/src/H5D.c
index 6ded25d..b4bedff 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -1387,9 +1387,6 @@ H5D_update_entry_info(H5F_t *file, hid_t dxpl_id, H5D_t *dset, H5P_genplist_t *p
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill time");
         dset->fill_time=fill_time;    /* Cache this for later */
 
-        if(fill_time==H5D_FILL_TIME_NEVER && H5T_detect_class(type, H5T_VLEN))
-            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Dataset doesn't support VL datatype when fill value is not defined");
-     
         /* Get the fill value information from the property list */
         if (H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, fill_prop) < 0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill value");
@@ -1398,6 +1395,17 @@ H5D_update_entry_info(H5F_t *file, hid_t dxpl_id, H5D_t *dset, H5P_genplist_t *p
     if (H5P_is_fill_value_defined(fill_prop, &fill_status) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
 
+    /* Special case handling for variable-length types */
+    if(H5T_detect_class(type, H5T_VLEN)) {
+        /* If the default fill value is chosen for variable-length types, always write it */
+        if(fill_time==H5D_FILL_TIME_IFSET && fill_status==H5D_FILL_VALUE_DEFAULT)
+            dset->fill_time=fill_time=H5D_FILL_TIME_ALLOC;
+
+        /* Don't allow never writing fill values with variable-length types */
+        if(fill_time==H5D_FILL_TIME_NEVER)
+            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Dataset doesn't support VL datatype when fill value is not defined");
+    } /* end if */
+
     if (fill_status == H5D_FILL_VALUE_DEFAULT || fill_status == H5D_FILL_VALUE_USER_DEFINED) {
         if (H5O_copy(H5O_FILL_ID, fill_prop, &fill) == NULL)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT,FAIL, "unable to copy fill value");
@@ -1417,7 +1425,7 @@ H5D_update_entry_info(H5F_t *file, hid_t dxpl_id, H5D_t *dset, H5P_genplist_t *p
     fill.alloc_time = alloc_time;
     fill.fill_time = fill_time;
    
-    if (fill.fill_defined == FALSE && fill_time != H5D_FILL_TIME_NEVER)
+    if (fill.fill_defined == FALSE && fill_time == H5D_FILL_TIME_ALLOC)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT,FAIL, "unable to create dataset");
 
     /* Write new fill value message */
@@ -2457,8 +2465,8 @@ H5D_alloc_storage (H5F_t *f, hid_t dxpl_id, H5D_t *dset/*in,out*/, H5D_time_allo
                 } /* end if */
 
                 /* If space allocation is set to 'early' and we are extending
-                 *  the dataset, indicate that space was allocated, so the
-                 * B-tree gets expanded. -QAK
+                 *  the dataset, indicate that space should be allocated, so the
+                 *  B-tree gets expanded. -QAK
                  */
                 if(dset->alloc_time==H5D_ALLOC_TIME_EARLY && time_alloc==H5D_ALLOC_EXTEND)
                     init_space=1;
@@ -2487,22 +2495,46 @@ H5D_alloc_storage (H5F_t *f, hid_t dxpl_id, H5D_t *dset/*in,out*/, H5D_time_allo
                 HGOTO_ERROR (H5E_IO, H5E_UNSUPPORTED, FAIL, "unsupported storage layout");
         } /* end switch */
 
-        /* Check if we actually allocated space before performing other actions */
-        if(init_space || addr_set) {
-            /* If we are filling the dataset on allocation, do that now */
-            if(dset->fill_time==H5D_FILL_TIME_ALLOC
-                    && !(dset->alloc_time==H5D_ALLOC_TIME_INCR && time_alloc==H5D_ALLOC_WRITE)) {
-                if(H5D_init_storage(dset, full_overwrite, dxpl_id) < 0)
-                    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset with fill value");
+        /* Check if we need to initialize the space */
+        if(init_space) {
+            if (layout->type==H5D_CHUNKED) {
+                /* If we are doing incremental allocation and the B-tree got
+                 * created during a H5Dwrite call, don't initialize the storage
+                 * now, wait for the actual writes to each block and let the
+                 * low-level chunking routines handle initialize the fill-values.
+                 * Otherwise, pass along the space initialization call and let
+                 * the low-level chunking routines sort out whether to write
+                 * fill values to the chunks they allocate space for.  Yes,
+                 * this is icky. -QAK
+                 */
+                if(!(dset->alloc_time==H5D_ALLOC_TIME_INCR && time_alloc==H5D_ALLOC_WRITE)) {
+                    if(H5D_init_storage(dset, full_overwrite, dxpl_id) < 0)
+                        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset with fill value");
+                } /* end if */
             } /* end if */
-
-            /* Also update header message for layout with new address, if we
-             * set the address.  (this is mainly for forward compatibility).
-             */
-            if(time_alloc!=H5D_ALLOC_CREATE && addr_set)
-                if (H5O_modify (&(dset->ent), H5O_LAYOUT_ID, 0, H5O_FLAG_CONSTANT, update_time, &(dset->layout), dxpl_id) < 0)
-                    HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update layout message");
+            else {
+                H5D_fill_value_t	fill_status;    /* The fill value status */
+
+                /* Check the dataset's fill-value status */
+                if (H5P_is_fill_value_defined(&(dset->fill), &fill_status) < 0)
+                    HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
+
+                /* If we are filling the dataset on allocation or "if set" and
+                 * the fill value _is_ set, do that now */
+                if(dset->fill_time==H5D_FILL_TIME_ALLOC ||
+                        (dset->fill_time==H5D_FILL_TIME_IFSET && fill_status==H5D_FILL_VALUE_USER_DEFINED)) {
+                    if(H5D_init_storage(dset, full_overwrite, dxpl_id) < 0)
+                        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset with fill value");
+                } /* end if */
+            } /* end else */
         } /* end if */
+
+        /* Also update header message for layout with new address, if we
+         * set the address.  (this is improves forward compatibility).
+         */
+        if(time_alloc!=H5D_ALLOC_CREATE && addr_set)
+            if (H5O_modify (&(dset->ent), H5O_LAYOUT_ID, 0, H5O_FLAG_CONSTANT, update_time, &(dset->layout), dxpl_id) < 0)
+                HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update layout message");
     } /* end if */
 
 done:
diff --git a/src/H5Distore.c b/src/H5Distore.c
index baeac20..2f9f3b0 100644
--- a/src/H5Distore.c
+++ b/src/H5Distore.c
@@ -1348,9 +1348,9 @@ done:
  */
 static void *
 H5F_istore_lock(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-		const H5O_pline_t *pline, const H5O_fill_t *fill,
-		const hssize_t offset[], hbool_t relax,
-		unsigned *idx_hint/*in,out*/)
+    const H5O_pline_t *pline, const H5O_fill_t *fill, H5D_fill_time_t fill_time,
+    const hssize_t offset[], hbool_t relax,
+    unsigned *idx_hint/*in,out*/)
 {
     int		idx=0;			/*hash index number	*/
     hsize_t	temp_idx=0;			/* temporary index number	*/
@@ -1458,24 +1458,33 @@ H5F_istore_lock(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
             }
             rdcc->nmisses++;
         } else {
+            H5D_fill_value_t	fill_status;
+
             /* Chunk size on disk isn't [likely] the same size as the final chunk
              * size in memory, so allocate memory big enough. */
             if (NULL==(chunk = H5MM_malloc (chunk_size)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for raw data chunk");
-            if (fill && fill->buf) {
-                /*
-                 * The chunk doesn't exist in the file.  Replicate the fill
-                 * value throughout the chunk.
-                 */
-                assert(0==chunk_size % fill->size);
-                H5V_array_fill(chunk, fill->buf, fill->size, chunk_size/fill->size);
-            } else {
-                /*
-                 * The chunk doesn't exist in the file and no fill value was
-                 * specified.  Assume all zeros.
-                 */
-                HDmemset (chunk, 0, chunk_size);
-            }
+
+            if (H5P_is_fill_value_defined(fill, &fill_status) < 0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't tell if fill value defined");
+
+            if(fill_time==H5D_FILL_TIME_ALLOC ||
+                    (fill_time==H5D_FILL_TIME_IFSET && fill_status==H5D_FILL_VALUE_USER_DEFINED)) {
+                if (fill && fill->buf) {
+                    /*
+                     * The chunk doesn't exist in the file.  Replicate the fill
+                     * value throughout the chunk.
+                     */
+                    assert(0==chunk_size % fill->size);
+                    H5V_array_fill(chunk, fill->buf, fill->size, chunk_size/fill->size);
+                } else {
+                    /*
+                     * The chunk doesn't exist in the file and no fill value was
+                     * specified.  Assume all zeros.
+                     */
+                    HDmemset (chunk, 0, chunk_size);
+                } /* end else */
+            } /* end if */
             rdcc->ninits++;
         } /* end else */
     }
@@ -1771,18 +1780,21 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
     else {
         uint8_t         *chunk;         /* Pointer to cached chunk in memory */
         H5O_fill_t      fill;           /* Fill value information */
+        H5D_fill_time_t fill_time;      /* Fill time information */
         unsigned        idx_hint=0;     /* Cache index hint      */
         ssize_t         naccessed;      /* Number of bytes accessed in chunk */
 
         /* Get necessary properties from property list */
         if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
+        if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill time");
 
         /*
          * Lock the chunk, copy from application to chunk, then unlock the
          * chunk.
          */
-        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill,
+        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill, fill_time,
                      chunk_coords_in_elmts, FALSE, &idx_hint)))
             HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "unable to read raw data chunk");
 
@@ -1902,6 +1914,7 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
     else {
         uint8_t         *chunk;         /* Pointer to cached chunk in memory */
         H5O_fill_t      fill;           /* Fill value information */
+        H5D_fill_time_t fill_time;      /* Fill time information */
         unsigned        idx_hint=0;     /* Cache index hint      */
         ssize_t         naccessed;      /* Number of bytes accessed in chunk */
         hbool_t         relax;          /* Whether whole chunk is selected */
@@ -1909,6 +1922,8 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
         /* Get necessary properties from property list */
         if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
+        if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill time");
 
         /*
          * Lock the chunk, copy from application to chunk, then unlock the
@@ -1919,7 +1934,7 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
         else
             relax = FALSE;
 
-        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill,
+        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill, fill_time,
                  chunk_coords_in_elmts, relax, &idx_hint)))
             HGOTO_ERROR (H5E_IO, H5E_WRITEERROR, FAIL, "unable to read raw data chunk");
 
@@ -2131,6 +2146,8 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     H5O_pline_t pline;          /* I/O pipeline information */
     H5O_fill_t fill;            /* Fill value information */
     H5D_fill_time_t fill_time;  /* When to write fill values */
+    H5D_fill_value_t fill_status;    /* The fill value status */
+    unsigned   should_fill=0;   /* Whether fill values should be written */
     H5F_istore_ud1_t udata;	/* B-tree pass-through for creating chunk */
     void *chunk=NULL;           /* Chunk buffer for writing fill values */
     H5P_genplist_t *dx_plist;   /* Data xfer property list */
@@ -2239,8 +2256,20 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
         chunk_size *= layout->dim[u];
     } /* end for */
 
+    /* Check the dataset's fill-value status */
+    if (H5P_is_fill_value_defined(&fill, &fill_status) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
+
+    /* If we are filling the dataset on allocation or "if set" and
+     * the fill value _is_ set, _and_ we are not overwriting the new blocks,
+     * set the "should fill" flag
+     */
+    if(!full_overwrite && (fill_time==H5D_FILL_TIME_ALLOC ||
+            (fill_time==H5D_FILL_TIME_IFSET && fill_status==H5D_FILL_VALUE_USER_DEFINED)))
+        should_fill=1;
+
     /* Check if fill values should be written to blocks */
-    if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
+    if(should_fill) {
         /* Allocate chunk buffer for processes to use when writing fill values */
         H5_CHECK_OVERFLOW(chunk_size,hsize_t,size_t);
         if (NULL==(chunk = H5MM_malloc((size_t)chunk_size)))
@@ -2318,7 +2347,7 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
                 HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to allocate chunk");
 
             /* Check if fill values should be written to blocks */
-            if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
+            if(should_fill) {
 #ifdef H5_HAVE_PARALLEL
                 /* Check if this file is accessed with an MPI-capable file driver */
                 if(using_mpi) {
@@ -2709,6 +2738,7 @@ H5F_istore_initialize_by_extent(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *lay
     int                     found = 0;	/*initialize this entry  */
     H5O_pline_t             pline;      /* I/O pipeline information */
     H5O_fill_t              fill;       /* Fill value information */
+    H5D_fill_time_t         fill_time;  /* Fill time information */
     herr_t	            ret_value=SUCCEED;	/* Return value */
 
     FUNC_ENTER_NOAPI(H5F_istore_initialize_by_extent, FAIL);
@@ -2723,6 +2753,8 @@ H5F_istore_initialize_by_extent(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *lay
     /* Get necessary properties from property list */
     if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
+    if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill time");
     if(H5P_get(dc_plist, H5D_CRT_DATA_PIPELINE_NAME, &pline) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get data pipeline");
 
@@ -2780,7 +2812,7 @@ H5F_istore_initialize_by_extent(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *lay
 
 	if(found) {
 
-	    if(NULL == (chunk = H5F_istore_lock(f, dxpl_id, layout, &pline, &fill,
+	    if(NULL == (chunk = H5F_istore_lock(f, dxpl_id, layout, &pline, &fill, fill_time,
 			    chunk_offset, FALSE, &idx_hint)))
 		HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to read raw data chunk");
 
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index f2bc489..b1615b0 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -59,7 +59,7 @@
 /* Definitions for time of fill value writing */
 #define H5D_CRT_FILL_TIME_NAME     "fill_time"
 #define H5D_CRT_FILL_TIME_SIZE     sizeof(H5D_fill_time_t)
-#define H5D_CRT_FILL_TIME_DEF      H5D_FILL_TIME_ALLOC 
+#define H5D_CRT_FILL_TIME_DEF      H5D_FILL_TIME_IFSET 
 /* Definitions for external file list */
 #define H5D_CRT_EXT_FILE_LIST_NAME "efl"
 #define H5D_CRT_EXT_FILE_LIST_SIZE sizeof(H5O_efl_t)
diff --git a/src/H5Dpublic.h b/src/H5Dpublic.h
index c0a23cb..5987b79 100644
--- a/src/H5Dpublic.h
+++ b/src/H5Dpublic.h
@@ -53,7 +53,8 @@ typedef enum H5D_space_status_t {
 typedef enum H5D_fill_time_t {
     H5D_FILL_TIME_ERROR	=-1,
     H5D_FILL_TIME_ALLOC =0,
-    H5D_FILL_TIME_NEVER	=1
+    H5D_FILL_TIME_NEVER	=1,
+    H5D_FILL_TIME_IFSET	=2
 } H5D_fill_time_t;
 
 /* Values for fill value status */
diff --git a/src/H5Fistore.c b/src/H5Fistore.c
index baeac20..2f9f3b0 100644
--- a/src/H5Fistore.c
+++ b/src/H5Fistore.c
@@ -1348,9 +1348,9 @@ done:
  */
 static void *
 H5F_istore_lock(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-		const H5O_pline_t *pline, const H5O_fill_t *fill,
-		const hssize_t offset[], hbool_t relax,
-		unsigned *idx_hint/*in,out*/)
+    const H5O_pline_t *pline, const H5O_fill_t *fill, H5D_fill_time_t fill_time,
+    const hssize_t offset[], hbool_t relax,
+    unsigned *idx_hint/*in,out*/)
 {
     int		idx=0;			/*hash index number	*/
     hsize_t	temp_idx=0;			/* temporary index number	*/
@@ -1458,24 +1458,33 @@ H5F_istore_lock(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
             }
             rdcc->nmisses++;
         } else {
+            H5D_fill_value_t	fill_status;
+
             /* Chunk size on disk isn't [likely] the same size as the final chunk
              * size in memory, so allocate memory big enough. */
             if (NULL==(chunk = H5MM_malloc (chunk_size)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for raw data chunk");
-            if (fill && fill->buf) {
-                /*
-                 * The chunk doesn't exist in the file.  Replicate the fill
-                 * value throughout the chunk.
-                 */
-                assert(0==chunk_size % fill->size);
-                H5V_array_fill(chunk, fill->buf, fill->size, chunk_size/fill->size);
-            } else {
-                /*
-                 * The chunk doesn't exist in the file and no fill value was
-                 * specified.  Assume all zeros.
-                 */
-                HDmemset (chunk, 0, chunk_size);
-            }
+
+            if (H5P_is_fill_value_defined(fill, &fill_status) < 0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't tell if fill value defined");
+
+            if(fill_time==H5D_FILL_TIME_ALLOC ||
+                    (fill_time==H5D_FILL_TIME_IFSET && fill_status==H5D_FILL_VALUE_USER_DEFINED)) {
+                if (fill && fill->buf) {
+                    /*
+                     * The chunk doesn't exist in the file.  Replicate the fill
+                     * value throughout the chunk.
+                     */
+                    assert(0==chunk_size % fill->size);
+                    H5V_array_fill(chunk, fill->buf, fill->size, chunk_size/fill->size);
+                } else {
+                    /*
+                     * The chunk doesn't exist in the file and no fill value was
+                     * specified.  Assume all zeros.
+                     */
+                    HDmemset (chunk, 0, chunk_size);
+                } /* end else */
+            } /* end if */
             rdcc->ninits++;
         } /* end else */
     }
@@ -1771,18 +1780,21 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
     else {
         uint8_t         *chunk;         /* Pointer to cached chunk in memory */
         H5O_fill_t      fill;           /* Fill value information */
+        H5D_fill_time_t fill_time;      /* Fill time information */
         unsigned        idx_hint=0;     /* Cache index hint      */
         ssize_t         naccessed;      /* Number of bytes accessed in chunk */
 
         /* Get necessary properties from property list */
         if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
+        if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill time");
 
         /*
          * Lock the chunk, copy from application to chunk, then unlock the
          * chunk.
          */
-        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill,
+        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill, fill_time,
                      chunk_coords_in_elmts, FALSE, &idx_hint)))
             HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "unable to read raw data chunk");
 
@@ -1902,6 +1914,7 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
     else {
         uint8_t         *chunk;         /* Pointer to cached chunk in memory */
         H5O_fill_t      fill;           /* Fill value information */
+        H5D_fill_time_t fill_time;      /* Fill time information */
         unsigned        idx_hint=0;     /* Cache index hint      */
         ssize_t         naccessed;      /* Number of bytes accessed in chunk */
         hbool_t         relax;          /* Whether whole chunk is selected */
@@ -1909,6 +1922,8 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
         /* Get necessary properties from property list */
         if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
+        if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill time");
 
         /*
          * Lock the chunk, copy from application to chunk, then unlock the
@@ -1919,7 +1934,7 @@ HDfprintf(stderr,"%s: mem_offset_arr[%Zu]=%Hu\n",FUNC,*mem_curr_seq,mem_offset_a
         else
             relax = FALSE;
 
-        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill,
+        if (NULL==(chunk=H5F_istore_lock(f, dxpl_id, layout, &pline, &fill, fill_time,
                  chunk_coords_in_elmts, relax, &idx_hint)))
             HGOTO_ERROR (H5E_IO, H5E_WRITEERROR, FAIL, "unable to read raw data chunk");
 
@@ -2131,6 +2146,8 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     H5O_pline_t pline;          /* I/O pipeline information */
     H5O_fill_t fill;            /* Fill value information */
     H5D_fill_time_t fill_time;  /* When to write fill values */
+    H5D_fill_value_t fill_status;    /* The fill value status */
+    unsigned   should_fill=0;   /* Whether fill values should be written */
     H5F_istore_ud1_t udata;	/* B-tree pass-through for creating chunk */
     void *chunk=NULL;           /* Chunk buffer for writing fill values */
     H5P_genplist_t *dx_plist;   /* Data xfer property list */
@@ -2239,8 +2256,20 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
         chunk_size *= layout->dim[u];
     } /* end for */
 
+    /* Check the dataset's fill-value status */
+    if (H5P_is_fill_value_defined(&fill, &fill_status) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
+
+    /* If we are filling the dataset on allocation or "if set" and
+     * the fill value _is_ set, _and_ we are not overwriting the new blocks,
+     * set the "should fill" flag
+     */
+    if(!full_overwrite && (fill_time==H5D_FILL_TIME_ALLOC ||
+            (fill_time==H5D_FILL_TIME_IFSET && fill_status==H5D_FILL_VALUE_USER_DEFINED)))
+        should_fill=1;
+
     /* Check if fill values should be written to blocks */
-    if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
+    if(should_fill) {
         /* Allocate chunk buffer for processes to use when writing fill values */
         H5_CHECK_OVERFLOW(chunk_size,hsize_t,size_t);
         if (NULL==(chunk = H5MM_malloc((size_t)chunk_size)))
@@ -2318,7 +2347,7 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
                 HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to allocate chunk");
 
             /* Check if fill values should be written to blocks */
-            if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
+            if(should_fill) {
 #ifdef H5_HAVE_PARALLEL
                 /* Check if this file is accessed with an MPI-capable file driver */
                 if(using_mpi) {
@@ -2709,6 +2738,7 @@ H5F_istore_initialize_by_extent(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *lay
     int                     found = 0;	/*initialize this entry  */
     H5O_pline_t             pline;      /* I/O pipeline information */
     H5O_fill_t              fill;       /* Fill value information */
+    H5D_fill_time_t         fill_time;  /* Fill time information */
     herr_t	            ret_value=SUCCEED;	/* Return value */
 
     FUNC_ENTER_NOAPI(H5F_istore_initialize_by_extent, FAIL);
@@ -2723,6 +2753,8 @@ H5F_istore_initialize_by_extent(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *lay
     /* Get necessary properties from property list */
     if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
+    if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill time");
     if(H5P_get(dc_plist, H5D_CRT_DATA_PIPELINE_NAME, &pline) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get data pipeline");
 
@@ -2780,7 +2812,7 @@ H5F_istore_initialize_by_extent(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *lay
 
 	if(found) {
 
-	    if(NULL == (chunk = H5F_istore_lock(f, dxpl_id, layout, &pline, &fill,
+	    if(NULL == (chunk = H5F_istore_lock(f, dxpl_id, layout, &pline, &fill, fill_time,
 			    chunk_offset, FALSE, &idx_hint)))
 		HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to read raw data chunk");
 
diff --git a/src/H5Pdcpl.c b/src/H5Pdcpl.c
index 2c9a377..7da0afc 100644
--- a/src/H5Pdcpl.c
+++ b/src/H5Pdcpl.c
@@ -1532,6 +1532,10 @@ H5Pset_fill_time(hid_t plist_id, H5D_fill_time_t fill_time)
     FUNC_ENTER_API(H5Pset_fill_time, FAIL);
     H5TRACE2("e","iDf",plist_id,fill_time);
 
+    /* Check arguments */
+    if(fill_time<H5D_FILL_TIME_ALLOC || fill_time>H5D_FILL_TIME_IFSET)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid fill time setting");
+
     /* Get the property list structure */
     if(NULL == (plist = H5P_object_verify(plist_id,H5P_DATASET_CREATE)))
         HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");