[svn-r22676] Changes needed to make the default free-list mapping from H5FD_FLMAP_SINGLE to H5FD_FLMAP_DICHOTOMY.

15 files changed, 402 insertions, 44 deletions

diff --git a/src/H5FDcore.c b/src/H5FDcore.c
index 8e2cf2a..932e2af 100644
--- a/src/H5FDcore.c
+++ b/src/H5FDcore.c
@@ -184,7 +184,7 @@ static const H5FD_class_t H5FD_core_g = {
     H5FD_core_truncate,				/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE 				/*fl_map		*/
+    H5FD_FLMAP_DICHOTOMY			/*fl_map		*/
 };
 
 
diff --git a/src/H5FDdirect.c b/src/H5FDdirect.c
index 218a1dd..4721a44 100644
--- a/src/H5FDdirect.c
+++ b/src/H5FDdirect.c
@@ -205,7 +205,7 @@ static const H5FD_class_t H5FD_direct_g = {
     H5FD_direct_truncate,      /*truncate    */
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE         /*fl_map    */
+    H5FD_FLMAP_DICHOTOMY                        /*fl_map                */
 };
 
 /* Declare a free list to manage the H5FD_direct_t struct */
diff --git a/src/H5FDfamily.c b/src/H5FDfamily.c
index 6f6d757..68f856a 100644
--- a/src/H5FDfamily.c
+++ b/src/H5FDfamily.c
@@ -148,7 +148,7 @@ static const H5FD_class_t H5FD_family_g = {
     H5FD_family_truncate,			/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE 				/*fl_map		*/
+    H5FD_FLMAP_DICHOTOMY                        /*fl_map                */
 };
 
 
diff --git a/src/H5FDlog.c b/src/H5FDlog.c
index b2c6398..6a2425c 100644
--- a/src/H5FDlog.c
+++ b/src/H5FDlog.c
@@ -233,7 +233,7 @@ static const H5FD_class_t H5FD_log_g = {
     H5FD_log_truncate,				/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE 				/*fl_map		*/
+    H5FD_FLMAP_DICHOTOMY			/*fl_map		*/
 };
 
 /* Declare a free list to manage the H5FD_log_t struct */
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 6dbe831..42e28b1 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -127,7 +127,7 @@ static const H5FD_class_mpi_t H5FD_mpio_g = {
     H5FD_mpio_truncate,				/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE                           /*fl_map                */
+    H5FD_FLMAP_DICHOTOMY                        /*fl_map                */
     },  /* End of superclass information */
     H5FD_mpio_mpi_rank,                         /*get_rank              */
     H5FD_mpio_mpi_size,                         /*get_size              */
diff --git a/src/H5FDmpiposix.c b/src/H5FDmpiposix.c
index 0ad39a9..4ed3a4d 100644
--- a/src/H5FDmpiposix.c
+++ b/src/H5FDmpiposix.c
@@ -236,7 +236,7 @@ static const H5FD_class_mpi_t H5FD_mpiposix_g = {
     H5FD_mpiposix_truncate,			/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE 				/*fl_map		*/
+    H5FD_FLMAP_DICHOTOMY                        /*fl_map                */
     },  /* End of superclass information */
     H5FD_mpiposix_mpi_rank,                     /*get_rank              */
     H5FD_mpiposix_mpi_size,                     /*get_size              */
diff --git a/src/H5FDsec2.c b/src/H5FDsec2.c
index 4201e07..241609d 100644
--- a/src/H5FDsec2.c
+++ b/src/H5FDsec2.c
@@ -191,7 +191,7 @@ static const H5FD_class_t H5FD_sec2_g = {
     H5FD_sec2_truncate,				/*truncate		*/
     NULL,                                       /*lock                  */
     NULL,                                       /*unlock                */
-    H5FD_FLMAP_SINGLE 				/*fl_map		*/
+    H5FD_FLMAP_DICHOTOMY                        /*fl_map                */
 };
 
 /* Declare a free list to manage the H5FD_sec2_t struct */
diff --git a/src/H5FDstdio.c b/src/H5FDstdio.c
index 4733eba..43bf6b9 100644
--- a/src/H5FDstdio.c
+++ b/src/H5FDstdio.c
@@ -226,7 +226,7 @@ static const H5FD_class_t H5FD_stdio_g = {
     H5FD_stdio_truncate,        /* truncate     */
     NULL,                       /* lock         */
     NULL,                       /* unlock       */
-    H5FD_FLMAP_SINGLE           /* fl_map       */
+    H5FD_FLMAP_DICHOTOMY	/* fl_map       */
 };
 
 
diff --git a/src/H5FSprivate.h b/src/H5FSprivate.h
index f6a0034..8cb3f95 100644
--- a/src/H5FSprivate.h
+++ b/src/H5FSprivate.h
@@ -200,6 +200,8 @@ H5_DLL herr_t H5FS_sect_stats(const H5FS_t *fspace, hsize_t *tot_space,
     hsize_t *nsects);
 H5_DLL herr_t H5FS_sect_change_class(H5F_t *f, hid_t dxpl_id, H5FS_t *fspace,
     H5FS_section_info_t *sect, unsigned new_class);
+H5_DLL htri_t H5FS_sect_try_shrink_eoa(const H5F_t *f, hid_t dxpl_id, const H5FS_t *fspace, void *op_data);
+H5_DLL herr_t H5FS_sect_query_last_sect(const H5FS_t *fspace, haddr_t *sect_addr, hsize_t *sect_size);
 
 /* Statistics routine */
 H5_DLL herr_t H5FS_stat_info(const H5F_t *f, const H5FS_t *frsp, H5FS_stat_t *stats);
diff --git a/src/H5FSsection.c b/src/H5FSsection.c
index 581d3dc..fa24f85 100644
--- a/src/H5FSsection.c
+++ b/src/H5FSsection.c
@@ -2377,3 +2377,114 @@ HDfprintf(stderr, "%s: sect->size = %Hu, sect->addr = %a, sect->type = %u\n", "H
 } /* end H5FS_sect_assert() */
 #endif /* H5FS_DEBUG_ASSERT */
 
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FS_sect_try_shrink_eoa
+ *
+ * Purpose:	To shrink the last section on the merge list if the section
+ *		is at EOF.
+ *
+ * Return:      Success:        non-negative (TRUE/FALSE)
+ *              Failure:        negative
+ *
+ * Programmer:	Vailin Choi
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5FS_sect_try_shrink_eoa(const H5F_t *f, hid_t dxpl_id, const H5FS_t *fspace, void *op_data)
+{
+    hbool_t sinfo_valid = FALSE;        /* Whether the section info is valid */
+    hbool_t section_removed = FALSE;    /* Whether a section was removed */
+    htri_t ret_value = FALSE;          	/* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Check arguments. */
+    HDassert(fspace);
+
+    if(H5FS_sinfo_lock(f, dxpl_id, fspace, H5AC_WRITE) < 0)
+        HGOTO_ERROR(H5E_FSPACE, H5E_CANTGET, FAIL, "can't get section info")
+    sinfo_valid = TRUE;
+
+    if(fspace->sinfo && fspace->sinfo->merge_list) {
+        H5SL_node_t *last_node;         	/* Last node in merge list */
+
+        /* Check for last node in the merge list */
+        if(NULL != (last_node = H5SL_last(fspace->sinfo->merge_list))) {
+            H5FS_section_info_t *tmp_sect;  	/* Temporary free space section */
+            H5FS_section_class_t *tmp_sect_cls;	/* Temporary section's class */
+
+            /* Get the pointer to the last section, from the last node */
+            tmp_sect = (H5FS_section_info_t *)H5SL_item(last_node);
+            HDassert(tmp_sect);
+	    tmp_sect_cls = &fspace->sect_cls[tmp_sect->type];
+	    if(tmp_sect_cls->can_shrink) {
+                /* Check if the section can be shrunk away */
+		if((ret_value = (*tmp_sect_cls->can_shrink)(tmp_sect, op_data)) < 0)
+		    HGOTO_ERROR(H5E_FSPACE, H5E_CANTSHRINK, FAIL, "can't check for shrinking container")
+		if(ret_value > 0) {
+		    HDassert(tmp_sect_cls->shrink);
+
+                    /* Remove section from free space manager */
+		    if(H5FS_sect_remove_real(fspace, tmp_sect) < 0)
+			HGOTO_ERROR(H5E_FSPACE, H5E_CANTRELEASE, FAIL, "can't remove section from internal data structures")
+                    section_removed = TRUE;
+
+                    /* Shrink away section */
+		    if((*tmp_sect_cls->shrink)(&tmp_sect, op_data) < 0)
+			HGOTO_ERROR(H5E_FSPACE, H5E_CANTINSERT, FAIL, "can't shrink free space container")
+		} /* end if */
+	    } /* end if */
+	} /* end if */
+    } /* end if */
+
+done:
+    /* Release the section info */
+    if(sinfo_valid && H5FS_sinfo_unlock(f, dxpl_id, fspace, section_removed) < 0)
+        HDONE_ERROR(H5E_FSPACE, H5E_CANTRELEASE, FAIL, "can't release section info")
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5FS_sect_try_shrink_eoa() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FS_sect_query_last_sect
+ *
+ * Purpose:	Retrieve info about the last section on the merge list
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Vailin Choi
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FS_sect_query_last_sect(const H5FS_t *fspace, haddr_t *sect_addr, hsize_t *sect_size)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Check arguments. */
+    HDassert(fspace);
+
+    if(fspace->sinfo && fspace->sinfo->merge_list) {
+        H5SL_node_t *last_node;             /* Last node in merge list */
+
+        /* Check for last node in the merge list */
+        if(NULL != (last_node = H5SL_last(fspace->sinfo->merge_list))) {
+            H5FS_section_info_t *tmp_sect;      /* Temporary free space section */
+
+            /* Get the pointer to the last section, from the last node */
+            tmp_sect = (H5FS_section_info_t *)H5SL_item(last_node);
+            HDassert(tmp_sect);
+	    if(sect_addr)
+                *sect_addr = tmp_sect->addr;
+	    if(sect_size)
+                *sect_size = tmp_sect->size;
+	} /* end if */
+    } /* end if */
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* H5FS_sect_query_last_sect() */
+
diff --git a/src/H5MF.c b/src/H5MF.c
index e708ab8..4b0668f 100644
--- a/src/H5MF.c
+++ b/src/H5MF.c
@@ -487,6 +487,7 @@ HDfprintf(stderr, "%s: Check 1.6, freeing node\n", FUNC);
                     udata.dxpl_id = dxpl_id;
                     udata.alloc_type = alloc_type;
                     udata.allow_sect_absorb = TRUE;
+		    udata.allow_eoa_shrink_only = FALSE; 
 
 #ifdef H5MF_ALLOC_DEBUG_MORE
 HDfprintf(stderr, "%s: Check 1.7, re-adding node, node->sect_info.size = %Hu\n", FUNC, node->sect_info.size);
@@ -692,6 +693,7 @@ HDfprintf(stderr, "%s: dropping addr = %a, size = %Hu, on the floor!\n", FUNC, a
     udata.dxpl_id = dxpl_id;
     udata.alloc_type = alloc_type;
     udata.allow_sect_absorb = TRUE;
+    udata.allow_eoa_shrink_only = FALSE; 
 
     /* If size of section freed is larger than threshold, add it to the free space manager */
     if(size >= f->shared->fs_threshold) {
@@ -823,6 +825,11 @@ H5MF_sects_dump(f, dxpl_id, stderr);
  * Programmer:  Quincey Koziol
  *              Monday, October  6, 2003
  *
+ * Modifications:
+ *      Vailin Choi; July 2012
+ *      As the default free-list mapping is changed to H5FD_FLMAP_DICHOTOMY,
+ *      checks are added to account for the last section of each free-space manager
+ *      and the remaining space in the two aggregators are at EOF.
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -836,6 +843,8 @@ H5MF_get_freespace(H5F_t *f, hid_t dxpl_id, hsize_t *tot_space, hsize_t *meta_si
     hsize_t tot_fs_size = 0;    /* Amount of all free space managed */
     hsize_t tot_meta_size = 0;  /* Amount of metadata for free space managers */
     H5FD_mem_t type;            /* Memory type for iteration */
+    H5FD_mem_t fs_started[H5FD_MEM_NTYPES]; /* Indicate whether the free-space manager has been started */
+    hbool_t eoa_shrank;		/* Whether an EOA shrink occurs */
     herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
@@ -859,14 +868,15 @@ H5MF_get_freespace(H5F_t *f, hid_t dxpl_id, hsize_t *tot_space, hsize_t *meta_si
 
     /* Iterate over all the free space types that have managers and get each free list's space */
     for(type = H5FD_MEM_DEFAULT; type < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, type)) {
-	hbool_t fs_started = FALSE;
+
+	fs_started[type] = FALSE;
 
 	/* Check if the free space for the file has been initialized */
         if(!f->shared->fs_man[type] && H5F_addr_defined(f->shared->fs_addr[type])) {
             if(H5MF_alloc_open(f, dxpl_id, type) < 0)
                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTINIT, FAIL, "can't initialize file free space")
             HDassert(f->shared->fs_man[type]);
-            fs_started = TRUE;
+            fs_started[type] = TRUE;
         } /* end if */
 
 	/* Check if there's free space of this type */
@@ -884,32 +894,54 @@ H5MF_get_freespace(H5F_t *f, hid_t dxpl_id, hsize_t *tot_space, hsize_t *meta_si
             tot_fs_size += type_fs_size;
             tot_meta_size += type_meta_size;
 	} /* end if */
+    } /* end for */
 
-	/* Close the free space manager, if we opened it here */
-        if(fs_started)
+    /* Iterate until no more EOA shrink occurs */
+    do {
+	eoa_shrank = FALSE;
+
+	/* Check the last section of each free-space manager */
+	for(type = H5FD_MEM_DEFAULT; type < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, type)) {
+	    haddr_t sect_addr = HADDR_UNDEF;
+	    hsize_t sect_size = 0;
+
+	    if(f->shared->fs_man[type]) {
+		if(H5FS_sect_query_last_sect(f->shared->fs_man[type], &sect_addr, &sect_size) < 0)
+		    HGOTO_ERROR(H5E_RESOURCE, H5E_CANTGET, FAIL, "can't query last section on merge list")
+
+		/* Deduct space from previous accumulation if the section is at EOA */
+		if(H5F_addr_eq(sect_addr + sect_size, eoa)) {
+		    eoa = sect_addr;
+		    eoa_shrank = TRUE;
+		    tot_fs_size -= sect_size;
+		} /* end if */
+	    } /* end if */
+	} /* end for */
+
+	/* Check the metadata and raw data aggregators */
+	if(ma_size > 0 && H5F_addr_eq(ma_addr + ma_size, eoa)) {
+	    eoa = ma_addr;
+	    eoa_shrank = TRUE;
+	    ma_size = 0;
+	} /* end if */
+	if(sda_size > 0 && H5F_addr_eq(sda_addr + sda_size, eoa)) {
+	    eoa = sda_addr;
+	    eoa_shrank = TRUE;
+	    sda_size = 0;
+	} /* end if */
+    } while(eoa_shrank);
+
+    /* Close the free-space managers if they were opened earlier in this routine */
+    for(type = H5FD_MEM_DEFAULT; type < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, type)) {
+	if(fs_started[type])
             if(H5MF_alloc_close(f, dxpl_id, type) < 0)
                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTINIT, FAIL, "can't close file free space")
     } /* end for */
 
-    /* Check for aggregating metadata allocations */
-    if(ma_size > 0) {
-        /* Add in the reserved space for metadata to the available free space */
-        /* (if it's not at the tail of the file) */
-        if(H5F_addr_ne(ma_addr + ma_size, eoa))
-            tot_fs_size += ma_size;
-    } /* end if */
-
-    /* Check for aggregating small data allocations */
-    if(sda_size > 0) {
-        /* Add in the reserved space for metadata to the available free space */
-        /* (if it's not at the tail of the file) */
-        if(H5F_addr_ne(sda_addr + sda_size, eoa))
-            tot_fs_size += sda_size;
-    } /* end if */
-
     /* Set the value(s) to return */
+    /* (The metadata & small data aggregators count as free space now, since they aren't at EOA) */
     if(tot_space)
-	*tot_space = tot_fs_size;
+	*tot_space = tot_fs_size + ma_size + sda_size;
     if(meta_size)
 	*meta_size = tot_meta_size;
 
@@ -961,6 +993,7 @@ HDfprintf(stderr, "%s: Entering - alloc_type = %u, addr = %a, size = %Hu\n", FUN
     udata.dxpl_id = dxpl_id;
     udata.alloc_type = alloc_type;
     udata.allow_sect_absorb = FALSE;    /* Force section to be absorbed into aggregator */
+    udata.allow_eoa_shrink_only = FALSE; 
 
     /* Call the "can shrink" callback for the section */
     if((ret_value = H5MF_sect_simple_can_shrink((const H5FS_section_info_t *)node, &udata)) < 0)
@@ -984,6 +1017,66 @@ HDfprintf(stderr, "%s: Leaving, ret_value = %d\n", FUNC, ret_value);
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5MF_close_shrink_eoa
+ *
+ * Purpose:     Shrink the EOA while closing
+ *
+ * Return:	SUCCEED/FAIL
+ *
+ * Programmer:  Quincey Koziol
+ *              Saturday, July 7, 2012
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5MF_close_shrink_eoa(H5F_t *f, hid_t dxpl_id)
+{
+    H5FD_mem_t type;            /* Memory type for iteration */
+    hbool_t eoa_shrank;		/* Whether an EOA shrink occurs */
+    htri_t status;		/* Status value */
+    H5MF_sect_ud_t udata;	/* User data for callback */
+    herr_t ret_value = SUCCEED;	/* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    /* check args */
+    HDassert(f);
+    HDassert(f->shared);
+
+    /* Construct user data for callbacks */
+    udata.f = f;
+    udata.dxpl_id = dxpl_id;
+    udata.allow_sect_absorb = FALSE;    
+    udata.allow_eoa_shrink_only = TRUE; 
+
+    /* Iterate until no more EOA shrinking occurs */
+    do {
+	eoa_shrank = FALSE;
+
+	/* Check the last section of each free-space manager */
+	for(type = H5FD_MEM_DEFAULT; type < H5FD_MEM_NTYPES; H5_INC_ENUM(H5FD_mem_t, type)) {
+	    if(f->shared->fs_man[type]) {
+		udata.alloc_type = type;
+		if((status = H5FS_sect_try_shrink_eoa(f, dxpl_id, f->shared->fs_man[type], &udata)) < 0)
+		    HGOTO_ERROR(H5E_FSPACE, H5E_CANTSHRINK, FAIL, "can't check for shrinking eoa")
+		else if(status > 0)
+		    eoa_shrank = TRUE;
+	    } /* end if */
+	} /* end for */
+
+	/* check the two aggregators */
+	if((status = H5MF_aggrs_try_shrink_eoa(f, dxpl_id)) < 0)
+	    HGOTO_ERROR(H5E_RESOURCE, H5E_CANTSHRINK, FAIL, "can't check for shrinking eoa")
+	else if(status > 0)
+	    eoa_shrank = TRUE;
+    } while(eoa_shrank);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5MF_close_shrink_eoa() */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5MF_close
  *
  * Purpose:     Close the free space tracker(s) for a file
@@ -993,6 +1086,12 @@ HDfprintf(stderr, "%s: Leaving, ret_value = %d\n", FUNC, ret_value);
  * Programmer:  Quincey Koziol
  *              Tuesday, January 22, 2008
  *
+ * Modifications:
+ *      Vailin Choi; July 2012
+ *      As the default free-list mapping is changed to H5FD_FLMAP_DICHOTOMY,
+ *      modifications are needed to shrink EOA if the last section of each free-space manager
+ *      and the remaining space in the two aggregators are at EOA.
+
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -1017,6 +1116,10 @@ HDfprintf(stderr, "%s: Entering\n", FUNC);
     if(H5MF_free_aggrs(f, dxpl_id) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTFREE, FAIL, "can't free aggregators")
 
+    /* Trying shrinking the EOA for the file */
+    if(H5MF_close_shrink_eoa(f, dxpl_id) < 0)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_CANTSHRINK, FAIL, "can't shrink eoa")
+
     /* Making free-space managers persistent for superblock version >= 2 */
     if(f->shared->sblock->super_vers >= HDF5_SUPERBLOCK_VERSION_2
             && f->shared->fs_strategy == H5F_FILE_SPACE_ALL_PERSIST) {
@@ -1164,6 +1267,11 @@ HDfprintf(stderr, "%s: Before deleting free space manager\n", FUNC);
     if(H5MF_free_aggrs(f, dxpl_id) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTFREE, FAIL, "can't free aggregators")
 
+    /* Trying shrinking the EOA for the file */
+    /* (in case any free space is now at the EOA) */
+    if(H5MF_close_shrink_eoa(f, dxpl_id) < 0)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_CANTSHRINK, FAIL, "can't shrink eoa")
+
 done:
 #ifdef H5MF_ALLOC_DEBUG
 HDfprintf(stderr, "%s: Leaving\n", FUNC);
diff --git a/src/H5MFaggr.c b/src/H5MFaggr.c
index 6f68fd7..f015b19 100644
--- a/src/H5MFaggr.c
+++ b/src/H5MFaggr.c
@@ -57,6 +57,8 @@
 /********************/
 /* Local Prototypes */
 /********************/
+static herr_t H5MF_aggr_free(H5F_t *f, hid_t dxpl_id, H5FD_mem_t type,
+    H5F_blk_aggr_t *aggr);
 
 
 /*********************/
@@ -231,15 +233,14 @@ HDfprintf(stderr, "%s: aggr = {%a, %Hu, %Hu}\n", FUNC, aggr->addr, aggr->tot_siz
                     if(H5F_addr_gt((eoa + size), f->shared->tmp_addr))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_BADRANGE, HADDR_UNDEF, "'normal' file space allocation request will overlap into 'temporary' file space")
 
+                    /* Release "other" aggregator, if it exists, is at the end of the allocated space,
+                     * has allocated more than one block and the unallocated space is greater than its
+                     * allocation block size.
+                     */
 		    if ((other_aggr->size > 0) && (H5F_addr_eq((other_aggr->addr + other_aggr->size), eoa)) &&
-			((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size)) {
-
-                            if(H5FD_free(f->shared->lf, dxpl_id, other_alloc_type, f, other_aggr->addr, other_aggr->size) < 0)
+			(other_aggr->tot_size > other_aggr->size) && ((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size)) {
+                            if(H5MF_aggr_free(f, dxpl_id, other_alloc_type, other_aggr) < 0)
                                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
-
-                            other_aggr->addr = 0;
-                            other_aggr->tot_size = 0;
-                            other_aggr->size = 0;
 		    } /* end if */
 
                     /* Allocate space from the VFD (i.e. at the end of the file) */
@@ -275,14 +276,14 @@ HDfprintf(stderr, "%s: Allocating block\n", FUNC);
                     if(H5F_addr_gt((eoa + aggr->alloc_size), f->shared->tmp_addr))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_BADRANGE, HADDR_UNDEF, "'normal' file space allocation request will overlap into 'temporary' file space")
 
+                    /* Release "other" aggregator, if it exists, is at the end of the allocated space,
+                     * has allocated more than one block and the unallocated space is greater than its
+                     * allocation block size.
+                     */
 		    if((other_aggr->size > 0) && (H5F_addr_eq((other_aggr->addr + other_aggr->size), eoa)) &&
-			((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size)) {
-
-                            if(H5FD_free(f->shared->lf, dxpl_id, other_alloc_type, f, other_aggr->addr, other_aggr->size) < 0)
+			(other_aggr->tot_size > other_aggr->size) && ((other_aggr->tot_size - other_aggr->size) >= other_aggr->alloc_size)) {
+                            if(H5MF_aggr_free(f, dxpl_id, other_alloc_type, other_aggr) < 0)
                                 HGOTO_ERROR(H5E_RESOURCE, H5E_CANTFREE, HADDR_UNDEF, "can't free aggregation block")
-                            other_aggr->addr = 0;
-                            other_aggr->tot_size = 0;
-                            other_aggr->size = 0;
 		    } /* end if */
 
                     /* Allocate space from the VFD (i.e. at the end of the file) */
@@ -633,8 +634,10 @@ H5MF_aggr_query(const H5F_t *f, const H5F_blk_aggr_t *aggr, haddr_t *addr,
 
     /* Check if this aggregator is active */
     if(f->shared->feature_flags & aggr->feature_flag) {
-        *addr = aggr->addr;
-        *size = aggr->size;
+	if(addr)
+            *addr = aggr->addr;
+        if(size)
+            *size = aggr->size;
     } /* end if */
 
     FUNC_LEAVE_NOAPI(SUCCEED)
@@ -766,3 +769,131 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5MF_free_aggrs() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:    H5MF_aggr_can_shrink_eoa
+ *
+ * Purpose:     Check if the remaining space in the aggregator is at EOA
+ *
+ * Return:      Success:        non-negative (TRUE/FALSE)
+ *              Failure:        negative
+ *
+ * Programmer:  Vailin Choi
+ *
+ *-------------------------------------------------------------------------
+ */
+static htri_t
+H5MF_aggr_can_shrink_eoa(H5F_t *f, H5FD_mem_t type, H5F_blk_aggr_t *aggr)
+{
+    haddr_t eoa = HADDR_UNDEF;      	/* EOA for the file */
+    htri_t ret_value = FALSE;   	/* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(f);
+    HDassert(aggr);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+
+    /* Get the EOA for the file */
+    if(HADDR_UNDEF == (eoa = H5F_get_eoa(f, type)))
+	HGOTO_ERROR(H5E_RESOURCE, H5E_CANTGET, FAIL, "Unable to get eoa")
+
+    /* Check if the aggregator is at EOA */
+    if(aggr->size > 0 && H5F_addr_defined(aggr->addr))
+	ret_value = H5F_addr_eq(eoa, aggr->addr + aggr->size);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5MF_aggr_can_shrink_eoa() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5MF_aggr_free
+ *
+ * Purpose:     Free the aggregator's space in the file.
+ *
+ * Note:        Does _not_ put the space on a free list
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Vailin Choi
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5MF_aggr_free(H5F_t *f, hid_t dxpl_id, H5FD_mem_t type, H5F_blk_aggr_t *aggr)
+{
+    herr_t ret_value = SUCCEED;   	/* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    HDassert(f);
+    HDassert(f->shared->lf);
+    HDassert(aggr);
+    HDassert(H5F_addr_defined(aggr->addr));
+    HDassert(aggr->size > 0);
+    HDassert(H5F_INTENT(f) & H5F_ACC_RDWR);
+    HDassert(aggr->feature_flag == H5FD_FEAT_AGGREGATE_METADATA || aggr->feature_flag == H5FD_FEAT_AGGREGATE_SMALLDATA);
+    HDassert(f->shared->feature_flags & aggr->feature_flag);
+
+    /* Free the remaining space at EOA in the aggregator */
+    if(H5FD_free(f->shared->lf, dxpl_id, type, f, aggr->addr, aggr->size) < 0)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_CANTFREE, FAIL, "can't free aggregation block")
+
+    /* Reset the aggregator */
+    aggr->tot_size = 0;
+    aggr->addr = HADDR_UNDEF;
+    aggr->size = 0;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5MF_aggr_free() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5MF_aggrs_try_shrink_eoa
+ *
+ * Purpose:     Check the metadata & small block aggregators to see if
+ *		EOA shrink is possible; if so, shrink each aggregator
+ *
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
+ *
+ * Programmer:  Vailin Choi
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5MF_aggrs_try_shrink_eoa(H5F_t *f, hid_t dxpl_id)
+{
+    htri_t ma_status;        /* Whether the metadata aggregator can shrink the EOA */
+    htri_t sda_status;       /* Whether the small data aggregator can shrink the EOA */
+    htri_t ret_value;        /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Check args */
+    HDassert(f);
+    HDassert(f->shared);
+
+    if((ma_status = H5MF_aggr_can_shrink_eoa(f, H5FD_MEM_DEFAULT, &(f->shared->meta_aggr))) < 0)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_CANTGET, FAIL, "can't query metadata aggregator stats")
+    if(ma_status > 0)
+	if(H5MF_aggr_free(f, dxpl_id, H5FD_MEM_DEFAULT, &(f->shared->meta_aggr)) < 0)
+	    HGOTO_ERROR(H5E_RESOURCE, H5E_CANTSHRINK, FAIL, "can't check for shrinking eoa")
+
+    if((sda_status = H5MF_aggr_can_shrink_eoa(f, H5FD_MEM_DRAW, &(f->shared->sdata_aggr))) < 0)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_CANTGET, FAIL, "can't query small data aggregator stats")
+    if(sda_status > 0)
+	if(H5MF_aggr_free(f, dxpl_id, H5FD_MEM_DRAW, &(f->shared->sdata_aggr)) < 0)
+	    HGOTO_ERROR(H5E_RESOURCE, H5E_CANTSHRINK, FAIL, "can't check for shrinking eoa")
+
+    ret_value = (ma_status || sda_status);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5MF_aggrs_try_shrink_eoa() */
+
diff --git a/src/H5MFpkg.h b/src/H5MFpkg.h
index 25785ae..2071a0a 100644
--- a/src/H5MFpkg.h
+++ b/src/H5MFpkg.h
@@ -122,6 +122,7 @@ typedef struct H5MF_sect_ud_t {
     hid_t dxpl_id;              /* DXPL for VFD operations */
     H5FD_mem_t alloc_type;      /* Type of memory being allocated */
     hbool_t allow_sect_absorb;  /* Whether sections are allowed to absorb a block aggregator */
+    hbool_t allow_eoa_shrink_only;  /* Whether shrinking eoa is allowed only for the section */
 
     /* Up */
     H5MF_shrink_type_t shrink;  /* Type of shrink operation to perform */
diff --git a/src/H5MFprivate.h b/src/H5MFprivate.h
index b471aa3..ad5e385 100644
--- a/src/H5MFprivate.h
+++ b/src/H5MFprivate.h
@@ -81,6 +81,7 @@ H5_DLL haddr_t H5MF_alloc_tmp(H5F_t *f, hsize_t size);
 
 /* 'block aggregator' routines */
 H5_DLL herr_t H5MF_free_aggrs(H5F_t *f, hid_t dxpl_id);
+H5_DLL htri_t H5MF_aggrs_try_shrink_eoa(H5F_t *f, hid_t dxpl_id);
 
 /* Debugging routines */
 #ifdef H5MF_DEBUGGING
diff --git a/src/H5MFsection.c b/src/H5MFsection.c
index 89b2219..0572def 100644
--- a/src/H5MFsection.c
+++ b/src/H5MFsection.c
@@ -328,6 +328,10 @@ HDfprintf(stderr, "%s: section {%a, %Hu}, shrinks file, eoa = %a\n", FUNC, sect-
         HGOTO_DONE(TRUE)
     } /* end if */
     else {
+        /* Shrinking can't occur if the 'eoa_shrink_only' flag is set and we're not shrinking the EOA */
+        if(udata->allow_eoa_shrink_only)
+            HGOTO_DONE(FALSE)
+
         /* Check if this section is allowed to merge with metadata aggregation block */
         if(udata->f->shared->fs_aggr_merge[udata->alloc_type] & H5F_FS_MERGE_METADATA) {
             htri_t status;              /* Status from aggregator adjoin */