[svn-r14594] Ported flash cache size increase code into the journaling branch --

note that both the H5C and H5C2 code have been updated.

Also checked in code to track journaling status in the super block.
Note that this code has not been tested -- but as best I can tell,
it does not break the existing regression tests.

Tested serial (debug and production) on Phoenix.  Also tested parallel
on kagiso.

Note that regression test fails on kagiso (but not on phoenix) if 
the cache2 serial tests are configured to use the core file driver.
Thus this code is check in with the core file driver optimization
of the cache2 tests disabled.  To turn it on, set the USE_CORE_DRIVER
#define to TRUE.

1 files changed, 955 insertions, 38 deletions

diff --git a/src/H5C.c b/src/H5C.c
index 8ac9929..daa5c8b 100644
--- a/src/H5C.c
+++ b/src/H5C.c
@@ -2596,6 +2596,10 @@ static herr_t H5C__autoadjust__ageout__remove_all_markers(H5C_t * cache_ptr);
 
 static herr_t H5C__autoadjust__ageout__remove_excess_markers(H5C_t * cache_ptr);
 
+static herr_t H5C__flash_increase_cache_size(H5C_t * cache_ptr,
+                                             size_t old_entry_size,
+                                             size_t new_entry_size);
+
 static herr_t H5C_flush_single_entry(H5F_t *             f,
                                      hid_t               primary_dxpl_id,
                                      hid_t               secondary_dxpl_id,
@@ -2836,8 +2840,12 @@ done:
  *		ro_ref_count fields.
  *
  *		JRM -- 7/27/07
-*		Added initialization for the new evictions_enabled 
-*		field of H5C_t.
+ *		Added initialization for the new evictions_enabled 
+ *		field of H5C_t.
+ *
+ *		JRM -- 12/31/07
+ *		Added initialization for the new flash cache size increase
+ *		related fields of H5C_t.
  *
  *-------------------------------------------------------------------------
  */
@@ -2954,6 +2962,8 @@ H5C_create(size_t		      max_cache_size,
     cache_ptr->dLRU_tail_ptr			= NULL;
 
     cache_ptr->size_increase_possible		= FALSE;
+    cache_ptr->flash_size_increase_possible     = FALSE;
+    cache_ptr->flash_size_increase_threshold    = 0;
     cache_ptr->size_decrease_possible		= FALSE;
     cache_ptr->resize_enabled			= FALSE;
     cache_ptr->cache_full			= FALSE;
@@ -2974,6 +2984,11 @@ H5C_create(size_t		      max_cache_size,
     (cache_ptr->resize_ctl).apply_max_increment	= TRUE;
     (cache_ptr->resize_ctl).max_increment	= H5C__DEF_AR_MAX_INCREMENT;
 
+    (cache_ptr->resize_ctl).flash_incr_mode	= H5C_flash_incr__off;
+    (cache_ptr->resize_ctl).flash_multiple	= 1.0;
+    (cache_ptr->resize_ctl).flash_threshold	= 0.25;
+
+
     (cache_ptr->resize_ctl).decr_mode		= H5C_decr__off;
     (cache_ptr->resize_ctl).upper_hr_threshold	= H5C__DEF_AR_UPPER_THRESHHOLD;
     (cache_ptr->resize_ctl).decrement	        = H5C__DEF_AR_DECREMENT;
@@ -2993,7 +3008,10 @@ H5C_create(size_t		      max_cache_size,
     for ( i = 0; i < H5C__MAX_EPOCH_MARKERS; i++ )
     {
         (cache_ptr->epoch_marker_active)[i]		 = FALSE;
-
+#ifndef NDEBUG
+	((cache_ptr->epoch_markers)[i]).magic            =
+		                                  H5C__H5C_CACHE_ENTRY_T_MAGIC;
+#endif /* NDEBUG */
         ((cache_ptr->epoch_markers)[i]).addr		 = (haddr_t)i;
         ((cache_ptr->epoch_markers)[i]).size		 = (size_t)0;
         ((cache_ptr->epoch_markers)[i]).type		 = &epoch_marker_class;
@@ -3079,6 +3097,9 @@ done:
  *		Updated function for display the new prefix field of
  *		H5C_t in output.
  *
+ *		JRM 12/31/07
+ *		Updated function to handle flash size increases.
+ *
  *-------------------------------------------------------------------------
  */
 void
@@ -3125,6 +3146,24 @@ H5C_def_auto_resize_rpt_fcn(H5C_t * cache_ptr,
                     new_min_clean_size);
             break;
 
+        case flash_increase:
+            HDassert( old_max_cache_size < new_max_cache_size );
+
+            HDfprintf(stdout,
+                      "%sflash cache resize(%d) -- size threshold = %Zu.\n",
+                      cache_ptr->prefix, 
+                      (int)((cache_ptr->resize_ctl).flash_incr_mode),
+                      cache_ptr->flash_size_increase_threshold); 
+
+            HDfprintf(stdout,
+                    "%s	cache size increased from (%Zu/%Zu) to (%Zu/%Zu).\n",
+                    cache_ptr->prefix,
+                    old_max_cache_size,
+                    old_min_clean_size,
+                    new_max_cache_size,
+                    new_min_clean_size);
+            break;
+
         case decrease:
             HDassert( old_max_cache_size > new_max_cache_size );
 
@@ -3537,6 +3576,21 @@ done:
  *		callbacks.  As a result, we may have to make multiple 
  *		passes through the skip list before the cache is flushed.
  *
+ *              JRM -- 10/13/07
+ *              Added code to detect and manage the case in which a
+ *              flush callback changes the s-list out from under
+ *              the function.  The only way I can think of in which this
+ *              can happen is if a flush function loads an entry
+ *              into the cache that isn't there already.  Quincey tells
+ *              me that this will never happen, but I'm not sure I
+ *              believe him.
+ *
+ *              Note that this is a pretty bad scenario if it ever
+ *              happens.  The code I have added should allow us to
+ *              handle the situation under all but the worst conditions, 
+ *              but one can argue that I should just scream and die if I 
+ *              ever detect the condidtion.
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -3558,6 +3612,7 @@ H5C_flush_cache(H5F_t *  f,
     int32_t		protected_entries = 0;
     H5SL_node_t * 	node_ptr = NULL;
     H5C_cache_entry_t *	entry_ptr = NULL;
+    H5C_cache_entry_t *	next_entry_ptr = NULL;
 #if H5C_DO_SANITY_CHECKS
     int64_t		flushed_entries_count;
     size_t		flushed_entries_size;
@@ -3620,6 +3675,28 @@ H5C_flush_cache(H5F_t *  f,
 	{
 	    flushed_entries_last_pass = FALSE;
             node_ptr = H5SL_first(cache_ptr->slist_ptr);
+
+            if ( node_ptr != NULL ) {
+
+                next_entry_ptr = (H5C_cache_entry_t *)H5SL_item(node_ptr);
+
+                if ( next_entry_ptr == NULL ) {
+
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+		                "next_entry_ptr == NULL 1 ?!?!");
+                }
+#ifndef NDEBUG
+		HDassert( next_entry_ptr->magic ==
+                          H5C__H5C_CACHE_ENTRY_T_MAGIC );
+#endif /* NDEBUG */
+	        HDassert( next_entry_ptr->is_dirty );
+                HDassert( next_entry_ptr->in_slist );
+
+            } else {
+
+                next_entry_ptr = NULL;
+
+            }
        
 	    HDassert( node_ptr != NULL );
 
@@ -3667,13 +3744,76 @@ H5C_flush_cache(H5F_t *  f,
 
 	    while ( node_ptr != NULL )
 	    {
-                entry_ptr = (H5C_cache_entry_t *)H5SL_item(node_ptr);
+                entry_ptr = next_entry_ptr;
+
+                /* With the advent of the fractal heap, it is possible
+		 * that the flush callback will dirty and/or resize
+		 * other entries in the cache.  In particular, while
+		 * Quincey has promised me that this will never happen,
+		 * it is possible that the flush callback for an
+		 * entry may protect an entry that is not in the cache,
+		 * perhaps causing the cache to flush and possibly
+		 * evict the entry associated with node_ptr to make
+		 * space for the new entry.
+		 *
+		 * Thus we do a bit of extra sanity checking on entry_ptr,
+		 * and break out of this scan of the skip list if we
+		 * detect minor problems.  We have a bit of leaway on the
+		 * number of passes though the skip list, so this shouldn't
+		 * be an issue in the flush in and of itself, as it should
+		 * be all but impossible for this to happen more than once
+		 * in any flush.
+		 *
+		 * Observe that that breaking out of the scan early
+		 * shouldn't break the sanity checks just after the end
+		 * of this while loop.
+		 *
+		 * If an entry has merely been marked clean and removed from
+		 * the s-list, we simply break out of the scan.
+		 *
+		 * If the entry has been evicted, we flag an error and
+		 * exit.
+		 */
+#ifndef NDEBUG
+		if ( entry_ptr->magic != H5C__H5C_CACHE_ENTRY_T_MAGIC ) {
+
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                "entry_ptr->magic invalid ?!?!");
+
+	        } else 
+#endif /* NDEBUG */
+		if ( ( ! entry_ptr->is_dirty ) ||
+                     ( ! entry_ptr->in_slist ) ) {
+
+                    /* the s-list has been modified out from under us.
+                     * set node_ptr to NULL and break out of the loop.
+                     */
+                    node_ptr = NULL;
+                    break;
+                }
 
                 /* increment node pointer now, before we delete its target
                  * from the slist.
                  */
                 node_ptr = H5SL_next(node_ptr);
 
+                if ( node_ptr != NULL ) {
+                    next_entry_ptr = (H5C_cache_entry_t *)H5SL_item(node_ptr);
+
+                    if ( next_entry_ptr == NULL ) {
+                        HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                    "next_entry_ptr == NULL 2 ?!?!");
+                    }
+#ifndef NDEBUG
+		    HDassert( next_entry_ptr->magic ==
+                              H5C__H5C_CACHE_ENTRY_T_MAGIC );
+#endif /* NDEBUG */
+                    HDassert( next_entry_ptr->is_dirty );
+                    HDassert( next_entry_ptr->in_slist );
+                } else {
+                    next_entry_ptr = NULL;
+                }
+
                 HDassert( entry_ptr != NULL );
                 HDassert( entry_ptr->in_slist );
 
@@ -3689,6 +3829,40 @@ H5C_flush_cache(H5F_t *  f,
                         tried_to_flush_protected_entry = TRUE;
 	                protected_entries++;
 
+                    } else if ( entry_ptr->is_pinned ) {
+			/* Test to see if we are can flush the entry now.
+			 * If we can, go ahead and flush.  Note that we
+			 * aren't trying to do a destroy here, so that
+			 * is not an issue.
+			 */
+                        if ( TRUE ) { /* When we get to multithreaded cache,
+                                       * we will need either locking code,
+                                       * and/or a test to see if the entry
+                                       * is in flushable condition here.
+                                       */
+#if H5C_DO_SANITY_CHECKS
+                            flushed_entries_count++;
+                            flushed_entries_size += entry_ptr->size;
+#endif /* H5C_DO_SANITY_CHECKS */
+                            status = H5C_flush_single_entry(f,
+                                                            primary_dxpl_id,
+                                                            secondary_dxpl_id,
+                                                            cache_ptr,
+                                                            NULL,
+                                                            entry_ptr->addr,
+                                                            flags,
+                                                            &first_flush,
+                                                            FALSE);
+                            if ( status < 0 ) {
+
+                                /* This shouldn't happen -- if it does, we are 
+			         * toast so just scream and die.
+                                 */
+                                HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, \
+                                            "dirty pinned entry flush failed.")
+                            }
+			    flushed_entries_last_pass = TRUE;
+			}
                     } else {
 #if H5C_DO_SANITY_CHECKS
                         flushed_entries_count++;
@@ -4434,6 +4608,9 @@ done:
  *		Added code to disable evictions when the new 
  *		evictions_enabled field is FALSE.
  *
+ *		JRM -- 12/31/07
+ *		Added code supporting flash cache size increases.
+ *
  *-------------------------------------------------------------------------
  */
 
@@ -4447,6 +4624,7 @@ H5C_insert_entry(H5F_t * 	     f,
                  void *		     thing,
                  unsigned int        flags)
 {
+    /* const char *	fcn_name = "H5C_insert_entry()"; */
     herr_t		result;
     herr_t		ret_value = SUCCEED;    /* Return value */
     hbool_t		first_flush = TRUE;
@@ -4486,7 +4664,9 @@ H5C_insert_entry(H5F_t * 	     f,
     insert_pinned    = ( (flags & H5C__PIN_ENTRY_FLAG) != 0 );
 
     entry_ptr = (H5C_cache_entry_t *)thing;
-
+#ifndef NDEBUG
+    entry_ptr->magic = H5C__H5C_CACHE_ENTRY_T_MAGIC;
+#endif /* NDEBUG */
     entry_ptr->addr = addr;
     entry_ptr->type = type;
 
@@ -4524,6 +4704,18 @@ H5C_insert_entry(H5F_t * 	     f,
 
     H5C__RESET_CACHE_ENTRY_STATS(entry_ptr)
 
+    if ( ( cache_ptr->flash_size_increase_possible ) &&
+         ( entry_ptr->size > cache_ptr->flash_size_increase_threshold ) ) {
+
+        result = H5C__flash_increase_cache_size(cache_ptr, 0, entry_ptr->size);
+
+        if ( result < 0 ) {
+
+            HGOTO_ERROR(H5E_CACHE, H5E_CANTINS, FAIL, \
+                        "H5C__flash_increase_cache_size failed.")
+        }
+    }
+
     if ( ( cache_ptr->evictions_enabled ) &&
          ( (cache_ptr->index_size + entry_ptr->size) > 
 	    cache_ptr->max_cache_size ) ) {
@@ -4999,7 +5191,9 @@ done:
  *
  * Modifications:
  *
- * 		None
+ * 		Added code to do a flash cache size increase if 
+ * 		appropriate.
+ * 						JRM -- 1/11/08
  *
  *-------------------------------------------------------------------------
  */
@@ -5010,6 +5204,8 @@ H5C_mark_pinned_entry_dirty(H5C_t * cache_ptr,
                             size_t  new_size)
 {
     herr_t              ret_value = SUCCEED;    /* Return value */
+    herr_t		result;
+    size_t		size_increase;
     H5C_cache_entry_t *	entry_ptr;
 
     FUNC_ENTER_NOAPI(H5C_mark_pinned_entry_dirty, FAIL)
@@ -5039,6 +5235,29 @@ H5C_mark_pinned_entry_dirty(H5C_t * cache_ptr,
     /* update for change in entry size if necessary */
     if ( ( size_changed ) && ( entry_ptr->size != new_size ) ) {
 
+        /* do a flash cache size increase if appropriate */
+        if ( cache_ptr->flash_size_increase_possible ) {
+
+            if ( new_size > entry_ptr->size ) {
+
+                size_increase = new_size - entry_ptr->size;
+
+                if ( size_increase >= 
+		     cache_ptr->flash_size_increase_threshold ) {
+
+                    result = H5C__flash_increase_cache_size(cache_ptr,
+                                                            entry_ptr->size,
+                                                            new_size);
+
+                    if ( result < 0 ) {
+
+                        HGOTO_ERROR(H5E_CACHE, H5E_CANTUNPROTECT, FAIL, \
+                                    "H5C__flash_increase_cache_size failed.")
+                    }
+                }
+            }
+        }
+
         /* update the protected entry list */
         H5C__DLL_UPDATE_FOR_SIZE_CHANGE((cache_ptr->pel_len), \
                                         (cache_ptr->pel_size), \
@@ -5371,7 +5590,9 @@ done:
  *
  * Modifications:
  *
- * 		None
+ * 		Added code to apply a flash cache size increment if 
+ * 		appropriate.
+ * 						JRM -- 1/11/08
  *
  *-------------------------------------------------------------------------
  */
@@ -5380,8 +5601,11 @@ H5C_resize_pinned_entry(H5C_t * cache_ptr,
                         void *  thing,
                         size_t  new_size)
 {
+    /* const char *	fcn_name = "H5C_resize_pinned_entry()"; */
     herr_t              ret_value = SUCCEED;    /* Return value */
+    herr_t		result;
     H5C_cache_entry_t *	entry_ptr;
+    size_t 		size_increase;
 
     FUNC_ENTER_NOAPI(H5C_resize_pinned_entry, FAIL)
 
@@ -5417,6 +5641,29 @@ H5C_resize_pinned_entry(H5C_t * cache_ptr,
     /* update for change in entry size if necessary */
     if ( entry_ptr->size != new_size ) {
 
+        /* do a flash cache size increase if appropriate */
+        if ( cache_ptr->flash_size_increase_possible ) {
+
+            if ( new_size > entry_ptr->size ) {
+
+                size_increase = new_size - entry_ptr->size;
+
+                if ( size_increase >= 
+		     cache_ptr->flash_size_increase_threshold ) {
+
+                    result = H5C__flash_increase_cache_size(cache_ptr,
+                                                            entry_ptr->size,
+                                                            new_size);
+
+                    if ( result < 0 ) {
+
+                        HGOTO_ERROR(H5E_CACHE, H5E_CANTUNPROTECT, FAIL, \
+                                    "H5C__flash_increase_cache_size failed.")
+                    }
+                }
+            }
+        }
+
         /* update the protected entry list */
         H5C__DLL_UPDATE_FOR_SIZE_CHANGE((cache_ptr->pel_len), \
                                         (cache_ptr->pel_size), \
@@ -5604,9 +5851,13 @@ done:
  * 		of cache entries.
  *
  * 		JRM -- 7/27/07
- * 		Added code supporting the new evictions_enabled fieled
+ * 		Added code supporting the new evictions_enabled field
  * 		in H5C_t.
  *
+ * 		JRM -- 1/3/08
+ * 		Added to do a flash cache size increase if appropriate 
+ * 		when a large entry is loaded.
+ *
  *-------------------------------------------------------------------------
  */
 
@@ -5621,6 +5872,7 @@ H5C_protect(H5F_t *	        f,
             void *	        udata2,
 	    unsigned		flags)
 {
+    /* const char *	fcn_name = "H5C_protect()"; */
     hbool_t		hit;
     hbool_t		first_flush;
     hbool_t		have_write_permitted = FALSE;
@@ -5678,7 +5930,25 @@ H5C_protect(H5F_t *	        f,
 
         entry_ptr = (H5C_cache_entry_t *)thing;
 
-        /* try to free up some space if necessary and if evictions are permitted */
+	/* If the entry is very large, and we are configured to allow it,
+	 * we may wish to perform a flash cache size increase.
+	 */
+        if ( ( cache_ptr->flash_size_increase_possible ) &&
+             ( entry_ptr->size > cache_ptr->flash_size_increase_threshold ) ) {
+
+            result = H5C__flash_increase_cache_size(cache_ptr, 0, 
+			                            entry_ptr->size);
+
+            if ( result < 0 ) {
+
+                HGOTO_ERROR(H5E_CACHE, H5E_CANTPROTECT, NULL, \
+                            "H5C__flash_increase_cache_size failed.")
+            }
+        }
+
+        /* try to free up some space if necessary and if evictions are 
+	 * permitted 
+	 */
         if ( ( cache_ptr->evictions_enabled ) &&
 	     ( (cache_ptr->index_size + entry_ptr->size) > 
 	       cache_ptr->max_cache_size ) ) {
@@ -5978,6 +6248,10 @@ done:
  *		if the new configuration forces an immediate reduction
  *		in cache size.
  *
+ *		JRM -- 12/31/07
+ *		Added code supporting the new flash cache size increase
+ *		code.
+ *
  *-------------------------------------------------------------------------
  */
 
@@ -5985,6 +6259,7 @@ herr_t
 H5C_set_cache_auto_resize_config(H5C_t * cache_ptr,
                                  H5C_auto_size_ctl_t *config_ptr)
 {
+    /* const char *fcn_name = "H5C_set_cache_auto_resize_config()"; */
     herr_t	ret_value = SUCCEED;      /* Return value */
     herr_t	result;
     size_t      new_max_cache_size;
@@ -6039,8 +6314,10 @@ H5C_set_cache_auto_resize_config(H5C_t * cache_ptr,
                     "conflicting threshold fields in new config.")
     }
 
-    cache_ptr->size_increase_possible = TRUE; /* will set to FALSE if needed */
-    cache_ptr->size_decrease_possible = TRUE; /* will set to FALSE if needed */
+    /* will set the increase possible fields to FALSE later if needed */
+    cache_ptr->size_increase_possible       = TRUE;
+    cache_ptr->flash_size_increase_possible = TRUE; 
+    cache_ptr->size_decrease_possible       = TRUE; 
 
     switch ( config_ptr->incr_mode )
     {
@@ -6062,6 +6339,11 @@ H5C_set_cache_auto_resize_config(H5C_t * cache_ptr,
             HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Unknown incr_mode?!?!?.")
     }
 
+    /* logically, this is were configuration for flash cache size increases
+     * should go.  However, this configuration depends on max_cache_size, so 
+     * we wait until the end of the function, when this field is set.
+     */
+
     switch ( config_ptr->decr_mode )
     {
         case H5C_decr__off:
@@ -6106,9 +6388,13 @@ H5C_set_cache_auto_resize_config(H5C_t * cache_ptr,
     if ( config_ptr->max_size == config_ptr->min_size ) {
 
         cache_ptr->size_increase_possible = FALSE;
+        cache_ptr->flash_size_increase_possible = FALSE; 
         cache_ptr->size_decrease_possible = FALSE;
     }
 
+    /* flash_size_increase_possible is intentionally omitted from the
+     * following:
+     */
     cache_ptr->resize_enabled = cache_ptr->size_increase_possible ||
                                 cache_ptr->size_decrease_possible;
 
@@ -6196,6 +6482,37 @@ H5C_set_cache_auto_resize_config(H5C_t * cache_ptr,
         }
     }
 
+    /* configure flash size increase facility.  We wait until the
+     * end of the function, as we need the max_cache_size set before 
+     * we start to keep things simple.
+     *
+     * If we haven't already ruled out flash cache size increases above,
+     * go ahead and configure it.
+     */
+
+    if ( cache_ptr->flash_size_increase_possible ) {
+
+        switch ( config_ptr->flash_incr_mode )
+        {
+            case H5C_flash_incr__off:
+                cache_ptr->flash_size_increase_possible = FALSE; 
+	        break;
+
+            case H5C_flash_incr__add_space:
+                cache_ptr->flash_size_increase_possible = TRUE; 
+                cache_ptr->flash_size_increase_threshold = 
+                    (size_t)
+                    (((double)(cache_ptr->max_cache_size)) *
+                     ((cache_ptr->resize_ctl).flash_threshold));
+                break;
+
+            default: /* should be unreachable */
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                            "Unknown flash_incr_mode?!?!?.")
+                break;
+        }
+    }	
+
 done:
 
     FUNC_LEAVE_NOAPI(ret_value)
@@ -7095,6 +7412,9 @@ done:
  *		Also added sanity checks using the new is_read_only and
  *		ro_ref_count parameters.
  *
+ *		JRM -- 12/31/07
+ *		Modified funtion to support flash cache resizes.
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -7108,6 +7428,7 @@ H5C_unprotect(H5F_t *		  f,
               unsigned int        flags,
               size_t              new_size)
 {
+    /* const char *	fcn_name = "H5C_unprotect()"; */
     hbool_t		deleted;
     hbool_t		dirtied;
     hbool_t             set_flush_marker;
@@ -7118,6 +7439,8 @@ H5C_unprotect(H5F_t *		  f,
     hbool_t		clear_entry = FALSE;
 #endif /* H5_HAVE_PARALLEL */
     herr_t              ret_value = SUCCEED;    /* Return value */
+    herr_t              result;
+    size_t		size_increase = 0;
     H5C_cache_entry_t *	entry_ptr;
     H5C_cache_entry_t *	test_entry_ptr;
 
@@ -7265,6 +7588,29 @@ H5C_unprotect(H5F_t *		  f,
         /* update for change in entry size if necessary */
         if ( ( size_changed ) && ( entry_ptr->size != new_size ) ) {
 
+            /* do a flash cache size increase if appropriate */
+            if ( cache_ptr->flash_size_increase_possible ) {
+
+                if ( new_size > entry_ptr->size ) {
+
+                    size_increase = new_size - entry_ptr->size;
+
+                    if ( size_increase >= 
+                         cache_ptr->flash_size_increase_threshold ) {
+
+                        result = H5C__flash_increase_cache_size(cache_ptr, 
+                                                              entry_ptr->size,
+                                                              new_size);
+
+                        if ( result < 0 ) {
+
+                            HGOTO_ERROR(H5E_CACHE, H5E_CANTUNPROTECT, FAIL, \
+                                        "H5C__flash_increase_cache_size failed.")
+                        }
+                    }
+                }
+            }
+
             /* update the protected list */
             H5C__DLL_UPDATE_FOR_SIZE_CHANGE((cache_ptr->pl_len), \
                                             (cache_ptr->pl_size), \
@@ -7458,7 +7804,9 @@ done:
  *
  * Modifications:
  *
- *		None.
+ *		Added validation for the flash increment fields.
+ *
+ *						JRM -- 12/31/07
  *
  *-------------------------------------------------------------------------
  */
@@ -7560,7 +7908,7 @@ H5C_validate_resize_config(H5C_auto_size_ctl_t * config_ptr,
                  ( config_ptr->apply_max_increment != FALSE ) ) {
 
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, \
-                            "apply_max_increment must be either TRUE or FALSE");
+                          "apply_max_increment must be either TRUE or FALSE");
             }
 
             /* no need to check max_increment, as it is a size_t,
@@ -7568,6 +7916,33 @@ H5C_validate_resize_config(H5C_auto_size_ctl_t * config_ptr,
              */
         } /* H5C_incr__threshold */
 
+        switch ( config_ptr->flash_incr_mode )
+        {
+	    case H5C_flash_incr__off:
+                /* nothing to do here */
+		break;
+
+	    case H5C_flash_incr__add_space:
+                if ( ( config_ptr->flash_multiple < 0.1 ) ||
+                     ( config_ptr->flash_multiple > 10.0 ) ) {
+
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, \
+                        "flash_multiple must be in the range [0.1, 10.0]");
+                }
+
+                if ( ( config_ptr->flash_threshold < 0.1 ) ||
+                     ( config_ptr->flash_threshold > 1.0 ) ) {
+
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, \
+                        "flash_threshold must be in the range [0.1, 1.0]");
+                }
+		break;
+
+	    default:
+                HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, \
+			    "Invalid flash_incr_mode");
+		break;
+	}
     } /* H5C_RESIZE_CFG__VALIDATE_INCREMENT */
 
 
@@ -7707,6 +8082,9 @@ done:
  *		reduction, and to adjust to changes in the
  *		H5C_auto_size_ctl_t structure.
  *
+ *		JRM -- 1/5/08
+ *		Added support for flash cache size increases.
+ *
  *-------------------------------------------------------------------------
  */
 
@@ -7990,6 +8368,30 @@ H5C__auto_adjust_cache_size(H5C_t * cache_ptr,
 
             cache_ptr->size_decreased = TRUE;
         }
+
+        /* update flash cache size increase fields as appropriate */
+        if ( cache_ptr->flash_size_increase_possible ) {
+
+            switch ( (cache_ptr->resize_ctl).flash_incr_mode )
+            {
+                case H5C_flash_incr__off:
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                       "flash_size_increase_possible but H5C_flash_incr__off?!")
+                    break;
+
+                case H5C_flash_incr__add_space:
+                    cache_ptr->flash_size_increase_threshold =
+                        (size_t)
+                        (((double)(cache_ptr->max_cache_size)) *
+                         ((cache_ptr->resize_ctl).flash_threshold));
+                    break;
+
+                default: /* should be unreachable */
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                "Unknown flash_incr_mode?!?!?.")
+                    break;
+            }
+        }
     }
 
     if ( (cache_ptr->resize_ctl).rpt_fcn != NULL ) {
@@ -8308,7 +8710,20 @@ done:
  *
  * Modifications:
  *
- *              None.
+ *              JRM -- 10/13/07
+ *              Added code to detect and manage the case in which a
+ *              flush callback changes the LRU-list out from under
+ *              the function.  The only way I can think of in which this
+ *              can happen is if a flush function loads an entry
+ *              into the cache that isn't there already.  Quincey tells
+ *              me that this will never happen, but I'm not sure I
+ *              believe him.
+ *
+ *              Note that this is a pretty bad scenario if it ever
+ *              happens.  The code I have added should allow us to
+ *              handle the situation under all but the worst conditions, 
+ *              but one can argue that I should just scream and die if I 
+ *              ever detect the condidtion.
  *
  *-------------------------------------------------------------------------
  */
@@ -8325,7 +8740,9 @@ H5C__autoadjust__ageout__evict_aged_out_entries(H5F_t * f,
     herr_t              result;
     size_t		eviction_size_limit;
     size_t		bytes_evicted = 0;
+    hbool_t             prev_is_dirty = FALSE;
     H5C_cache_entry_t * entry_ptr;
+    H5C_cache_entry_t * next_ptr;
     H5C_cache_entry_t * prev_ptr;
 
     FUNC_ENTER_NOAPI_NOINIT(H5C__autoadjust__ageout__evict_aged_out_entries)
@@ -8358,8 +8775,14 @@ H5C__autoadjust__ageout__evict_aged_out_entries(H5F_t * f,
         {
             HDassert( ! (entry_ptr->is_protected) );
 
+	    next_ptr = entry_ptr->next;
             prev_ptr = entry_ptr->prev;
 
+	    if ( prev_ptr != NULL ) {
+
+                prev_is_dirty = prev_ptr->is_dirty;
+            }
+
             if ( entry_ptr->is_dirty ) {
 
                 result = H5C_flush_single_entry(f,
@@ -8392,8 +8815,41 @@ H5C__autoadjust__ageout__evict_aged_out_entries(H5F_t * f,
                             "unable to flush entry")
             }
 
-            entry_ptr = prev_ptr;
+            if ( prev_ptr != NULL ) {
+#ifndef NDEBUG
+                if ( prev_ptr->magic != H5C__H5C_CACHE_ENTRY_T_MAGIC ) {
+
+                   /* something horrible has happened to *prev_ptr --
+                    * scream and die.
+                    */
+                   HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                               "*prev_ptr corrupt")
+
+                } else 
+#endif /* NDEBUG */
+		if ( ( prev_ptr->is_dirty != prev_is_dirty )
+                            ||
+                            ( prev_ptr->next != next_ptr )
+                            ||
+                            ( prev_ptr->is_protected )
+                            ||
+                            ( prev_ptr->is_pinned ) ) {
+
+                    /* something has happened to the LRU -- start over
+                     * from the tail.
+                     */
+                    entry_ptr = cache_ptr->LRU_tail_ptr;
+
+                } else {
+
+                    entry_ptr = prev_ptr;
 
+                }
+            } else {
+
+                entry_ptr = NULL;
+
+            }
         } /* end while */
 
         /* for now at least, don't bother to maintain the minimum clean size,
@@ -8741,6 +9197,173 @@ done:
 
 } /* H5C__autoadjust__ageout__remove_excess_markers() */
 
+/*-------------------------------------------------------------------------
+ *
+ * Function:	H5C__flash_increase_cache_size
+ *
+ * Purpose:    	If there is not at least new_entry_size - old_entry_size
+ *		bytes of free space in the cache and the current 
+ *              max_cache_size is less than (cache_ptr->resize_ctl).max_size, 
+ *              perform a flash increase in the cache size and then reset 
+ *              the full cache hit rate statistics, and exit.
+ *
+ * Return:      Non-negative on success/Negative on failure.
+ *
+ * Programmer:  John Mainzer, 12/31/07
+ *
+ * Modifications:
+ *
+ *		None.
+ *
+ *-------------------------------------------------------------------------
+ */
+
+static herr_t
+H5C__flash_increase_cache_size(H5C_t * cache_ptr,
+                               size_t old_entry_size,
+                               size_t new_entry_size)
+{
+    /* const char *	fcn_name = "H5C__flash_increase_cache_size()";*/
+    herr_t			ret_value = SUCCEED;      /* Return value */
+    size_t			new_max_cache_size = 0;
+    size_t			old_max_cache_size = 0;
+    size_t			new_min_clean_size = 0;
+    size_t			old_min_clean_size = 0;
+    size_t                      space_needed;
+    enum H5C_resize_status	status = flash_increase; /* may change */
+    double			hit_rate;
+
+    FUNC_ENTER_NOAPI_NOINIT(H5C__flash_increase_cache_size)
+    HDassert( cache_ptr );
+    HDassert( cache_ptr->magic == H5C__H5C_T_MAGIC );
+    HDassert( cache_ptr->flash_size_increase_possible );
+    HDassert( new_entry_size > cache_ptr->flash_size_increase_threshold );
+    HDassert( old_entry_size < new_entry_size );
+
+    if ( old_entry_size >= new_entry_size ) {
+
+        HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                    "old_entry_size >= new_entry_size")
+    }
+
+    space_needed = new_entry_size - old_entry_size;
+
+    if ( ( (cache_ptr->index_size + space_needed) > 
+                           cache_ptr->max_cache_size ) &&
+         ( cache_ptr->max_cache_size < (cache_ptr->resize_ctl).max_size ) ) {
+
+        /* we have work to do */
+
+        switch ( (cache_ptr->resize_ctl).flash_incr_mode ) 
+        {
+            case H5C_flash_incr__off:
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                   "flash_size_increase_possible but H5C_flash_incr__off?!")
+                break;
+
+            case H5C_flash_incr__add_space:
+		if ( cache_ptr->index_size < cache_ptr->max_cache_size ) {
+                
+		    HDassert( (cache_ptr->max_cache_size - cache_ptr->index_size)
+				    < space_needed );
+                    space_needed -= cache_ptr->max_cache_size - cache_ptr->index_size;
+		}
+		space_needed = 
+		    (size_t)(((double)space_needed) * 
+			     (cache_ptr->resize_ctl).flash_multiple);
+
+                new_max_cache_size = cache_ptr->max_cache_size + space_needed;
+
+                break;
+
+            default: /* should be unreachable */
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                            "Unknown flash_incr_mode?!?!?.")
+                break;
+        }
+
+        if ( new_max_cache_size > (cache_ptr->resize_ctl).max_size ) {
+
+	    new_max_cache_size = (cache_ptr->resize_ctl).max_size;
+        }
+
+        HDassert( new_max_cache_size > cache_ptr->max_cache_size );
+
+        new_min_clean_size = (size_t)
+                             ((double)new_max_cache_size *
+                              ((cache_ptr->resize_ctl).min_clean_fraction));
+
+        HDassert( new_min_clean_size <= new_max_cache_size );
+
+        old_max_cache_size = cache_ptr->max_cache_size;
+        old_min_clean_size = cache_ptr->min_clean_size;
+
+        cache_ptr->max_cache_size = new_max_cache_size;
+        cache_ptr->min_clean_size = new_min_clean_size;
+
+        /* update flash cache size increase fields as appropriate */
+        HDassert ( cache_ptr->flash_size_increase_possible );
+
+        switch ( (cache_ptr->resize_ctl).flash_incr_mode )
+        {
+            case H5C_flash_incr__off:
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                   "flash_size_increase_possible but H5C_flash_incr__off?!")
+                break;
+
+            case H5C_flash_incr__add_space:
+                cache_ptr->flash_size_increase_threshold =
+                    (size_t)
+                    (((double)(cache_ptr->max_cache_size)) *
+                     ((cache_ptr->resize_ctl).flash_threshold));
+                break;
+
+            default: /* should be unreachable */
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                            "Unknown flash_incr_mode?!?!?.")
+                break;
+        }
+
+        /* note that we don't cycle the epoch markers.  We can 
+         * argue either way as to whether we should, but for now
+         * we don't.
+         */
+
+        if ( (cache_ptr->resize_ctl).rpt_fcn != NULL ) {
+
+	    /* get the hit rate for the reporting function.  Should still
+	     * be good as we havent reset the hit rate statistics.
+	     */
+            if ( H5C_get_cache_hit_rate(cache_ptr, &hit_rate) != SUCCEED ) {
+
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "Can't get hit rate.")
+            }
+
+            (*((cache_ptr->resize_ctl).rpt_fcn))
+                (cache_ptr,
+                 H5C__CURR_AUTO_RESIZE_RPT_FCN_VER,
+                 hit_rate,
+                 status,
+                 old_max_cache_size,
+                 new_max_cache_size,
+                 old_min_clean_size,
+                 new_min_clean_size);
+        }
+
+        if ( H5C_reset_cache_hit_rate_stats(cache_ptr) != SUCCEED ) {
+
+            /* this should be impossible... */
+            HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                        "H5C_reset_cache_hit_rate_stats failed.")
+        }
+    }
+
+done:
+
+    FUNC_LEAVE_NOAPI(ret_value)
+
+} /* H5C__flash_increase_cache_size() */
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5C_flush_invalidate_cache
@@ -8779,12 +9402,28 @@ done:
  *
  * Modifications:
  *
- *		 To support the fractal heap, the cache must now deal with
- *		 entries being dirtied, resized, and/or renamed inside
- *		 flush callbacks.  Updated function to support this.
+ *		To support the fractal heap, the cache must now deal with
+ *		entries being dirtied, resized, and/or renamed inside
+ *		flush callbacks.  Updated function to support this.
  *
  *		                                     -- JRM 8/27/06
  *
+ *              Added code to detect and manage the case in which a
+ *              flush callback changes the s-list out from under
+ *              the function.  The only way I can think of in which this
+ *              can happen is if a flush function loads an entry
+ *              into the cache that isn't there already.  Quincey tells
+ *              me that this will never happen, but I'm not sure I
+ *              believe him.
+ *
+ *              Note that this is a pretty bad scenario if it ever
+ *              happens.  The code I have added should allow us to
+ *              handle the situation under all but the worst conditions, 
+ *              but one can argue that I should just scream and die if I 
+ *              ever detect the condidtion.
+ *
+ * 							-- JRM 10/13/07
+ *
  *-------------------------------------------------------------------------
  */
 herr_t
@@ -8895,6 +9534,23 @@ H5C_flush_invalidate_cache(H5F_t *  f,
 
             node_ptr = H5SL_first(cache_ptr->slist_ptr);
 
+            if ( node_ptr == NULL ) {
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                            "slist_len != 0 && node_ptr == NULL");
+            }
+
+            next_entry_ptr = (H5C_cache_entry_t *)H5SL_item(node_ptr);
+
+            if ( next_entry_ptr == NULL ) {
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                            "next_entry_ptr == NULL 1 ?!?!");
+            }
+#ifndef NDEBUG
+	    HDassert( next_entry_ptr->magic == H5C__H5C_CACHE_ENTRY_T_MAGIC );
+#endif /* NDEBUG */
+            HDassert( next_entry_ptr->is_dirty );
+            HDassert( next_entry_ptr->in_slist );
+
         }
 #if H5C_DO_SANITY_CHECKS
         /* Depending on circumstances, H5C_flush_single_entry() will
@@ -8927,23 +9583,88 @@ H5C_flush_invalidate_cache(H5F_t *  f,
 
         while ( node_ptr != NULL )
         {
-	    /* Note that we now remove nodes from the slist as we flush
-             * the associated entries, instead of leaving them there
-             * until we are done, and then destroying all nodes in
-             * the slist.
+            entry_ptr = next_entry_ptr;
+
+            /* With the advent of the fractal heap, it is possible
+             * that the flush callback will dirty and/or resize
+             * other entries in the cache.  In particular, while
+             * Quincey has promised me that this will never happen,
+             * it is possible that the flush callback for an
+             * entry may protect an entry that is not in the cache,
+             * perhaps causing the cache to flush and possibly
+             * evict the entry associated with node_ptr to make
+             * space for the new entry.
              *
-             * While this optimization used to be easy, with the possibility
-	     * of new entries being added to the slist in the midst of the 
-	     * flush, we must keep the slist in cannonical form at all 
-	     * times.
+             * Thus we do a bit of extra sanity checking on entry_ptr,
+             * and break out of this scan of the skip list if we
+             * detect major problems.  We have a bit of leaway on the
+             * number of passes though the skip list, so this shouldn't
+             * be an issue in the flush in and of itself, as it should
+             * be all but impossible for this to happen more than once
+             * in any flush.
+             *
+             * Observe that that breaking out of the scan early
+             * shouldn't break the sanity checks just after the end
+	     * of this while loop.
+	     *
+	     * If an entry has merely been marked clean and removed from
+	     * the s-list, we simply break out of the scan.
+	     *
+	     * If the entry has been evicted, we flag an error and
+	     * exit.
              */
+#ifndef NDEBUG
+	    if ( entry_ptr->magic != H5C__H5C_CACHE_ENTRY_T_MAGIC ) {
+
+                HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                            "entry_ptr->magic is invalid ?!?!");
+
+	    } else 
+#endif /* NDEBUG */
+	    if ( ( ! entry_ptr->is_dirty ) ||
+                 ( ! entry_ptr->in_slist ) ) {
 
-            entry_ptr = (H5C_cache_entry_t *)H5SL_item(node_ptr);
+                /* the s-list has been modified out from under us.
+	         * break out of the loop.
+                 */
+                break;
+            }
 
             /* increment node pointer now, before we delete its target
              * from the slist.
              */
+
             node_ptr = H5SL_next(node_ptr);
+            if ( node_ptr != NULL ) {
+
+                next_entry_ptr = (H5C_cache_entry_t *)H5SL_item(node_ptr);
+
+                if ( next_entry_ptr == NULL ) {
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                "next_entry_ptr == NULL 2 ?!?!");
+                }
+#ifndef NDEBUG
+		HDassert( next_entry_ptr->magic ==
+                          H5C__H5C_CACHE_ENTRY_T_MAGIC );
+#endif /* NDEBUG */
+                HDassert( next_entry_ptr->is_dirty );
+                HDassert( next_entry_ptr->in_slist );
+
+            } else {
+
+                next_entry_ptr = NULL;
+	    }
+
+            /* Note that we now remove nodes from the slist as we flush
+	     * the associated entries, instead of leaving them there
+	     * until we are done, and then destroying all nodes in
+             * the slist.
+             *
+             * While this optimization used to be easy, with the possibility
+             * of new entries being added to the slist in the midst of the
+             * flush, we must keep the slist in cannonical form at all
+             * times.
+             */
 
             HDassert( entry_ptr != NULL );
             HDassert( entry_ptr->in_slist );
@@ -9030,12 +9751,19 @@ H5C_flush_invalidate_cache(H5F_t *  f,
 	/* It is possible that entries were added to the slist during
 	 * the scan, either before or after scan pointer.  The following
 	 * asserts take this into account.
-	 */
+         *
+         * Don't bother with the sanity checks if node_ptr != NULL, as
+         * in this case we broke out of the loop because it got changed
+         * out from under us.
+         */
+
+	if ( node_ptr == NULL ) {
 
-        HDassert( (actual_slist_len + cache_ptr->slist_len) == 
-		  (initial_slist_len + cache_ptr->slist_len_increase) );
-        HDassert( (actual_slist_size + cache_ptr->slist_size) == 
-		  (initial_slist_size + cache_ptr->slist_size_increase) );
+            HDassert( (actual_slist_len + cache_ptr->slist_len) == 
+		      (initial_slist_len + cache_ptr->slist_len_increase) );
+            HDassert( (actual_slist_size + cache_ptr->slist_size) == 
+		      (initial_slist_size + cache_ptr->slist_size_increase) );
+	}
 #endif /* H5C_DO_SANITY_CHECKS */
 
         /* Since we are doing a destroy, we must make a pass through
@@ -9056,8 +9784,13 @@ H5C_flush_invalidate_cache(H5F_t *  f,
             while ( next_entry_ptr != NULL )
             {
                 entry_ptr = next_entry_ptr;
-                next_entry_ptr = entry_ptr->ht_next;
 
+                next_entry_ptr = entry_ptr->ht_next;
+#ifndef NDEBUG
+		HDassert ( ( next_entry_ptr == NULL ) ||
+                           ( next_entry_ptr->magic ==
+                             H5C__H5C_CACHE_ENTRY_T_MAGIC ) );
+#endif /* NDEBUG */
                 if ( entry_ptr->is_protected ) {
 
                     /* we have major problems -- but lets flush and destroy
@@ -9099,6 +9832,28 @@ H5C_flush_invalidate_cache(H5F_t *  f,
 		 * of pinned entries from pass to pass.  If it stops
 		 * shrinking before it hits zero, we scream and die.
 		 */
+                /* if the flush function on the entry we last evicted
+                 * loaded an entry into cache (as Quincey has promised me
+                 * it never will), and if the cache was full, it is
+                 * possible that *next_entry_ptr was flushed or evicted.
+                 *
+                 * Test to see if this happened here.  Note that if this 
+		 * test is triggred, we are accessing a deallocated piece 
+		 * of dynamically allocated memory, so we just scream and 
+		 * die.
+                 */
+#ifndef NDEBUG
+                if ( ( next_entry_ptr != NULL ) &&
+                     ( next_entry_ptr->magic !=
+                       H5C__H5C_CACHE_ENTRY_T_MAGIC ) ) {
+
+                    /* Something horrible has happened to
+                     * *next_entry_ptr -- scream and die.
+                     */
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                "next_entry_ptr->magic is invalid?!?!?.")
+                }
+#endif /* NDEBUG */
             } /* end while loop scanning hash table bin */
         } /* end for loop scanning hash table */
 
@@ -9541,6 +10296,17 @@ H5C_flush_single_entry(H5F_t *		   f,
         /* Clear the dirty flag only, if requested */
         if ( clear_only ) {
 
+#ifndef NDEBUG
+	    if ( destroy ) {
+		/* we are about to call the clear callback with the 
+		 * destroy flag set -- this will result in *entry_ptr
+		 * being freed.  Set the magic field to bad magic
+		 * so we can detect a freed cache entry if we see
+		 * one.
+		 */
+		entry_ptr->magic = H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC;
+	    }
+#endif /* NDEBUG */
             /* Call the callback routine to clear all dirty flags for object */
             if ( (entry_ptr->type->clear)(f, entry_ptr, destroy) < 0 ) {
 
@@ -9558,6 +10324,18 @@ H5C_flush_single_entry(H5F_t *		   f,
             }
 #endif /* H5C_DO_SANITY_CHECKS */
 
+#ifndef NDEBUG
+	    if ( destroy ) {
+	        /* we are about to call the flush callback with the 
+	         * destroy flag set -- this will result in *entry_ptr
+	         * being freed.  Set the magic field to bad magic
+	         * so we can detect a freed cache entry if we see
+	         * one.
+	         */
+	        entry_ptr->magic = H5C__H5C_CACHE_ENTRY_T_BAD_MAGIC;
+	    }
+#endif /* NDEBUG */
+
             /* Only block for all the processes on the first piece of metadata
              */
 
@@ -9816,7 +10594,9 @@ H5C_load_entry(H5F_t *             f,
      */
 
     HDassert( ( entry_ptr->is_dirty == FALSE ) || ( type->id == 4 ) );
-
+#ifndef NDEBUG
+    entry_ptr->magic = H5C__H5C_CACHE_ENTRY_T_MAGIC;
+#endif /* NDEBUG */
     entry_ptr->addr = addr;
     entry_ptr->type = type;
     entry_ptr->is_protected = FALSE;
@@ -9914,6 +10694,21 @@ done:
  *		Added sanity checks using the new is_read_only and 
  *		ro_ref_count fields.
  *
+ *              JRM -- 10/13/07
+ *              Added code to detect and manage the case in which a
+ *              flush callback changes the LRU-list out from under
+ *              the function.  The only way I can think of in which this
+ *              can happen is if a flush function loads an entry
+ *              into the cache that isn't there already.  Quincey tells
+ *              me that this will never happen, but I'm not sure I
+ *              believe him.
+ *
+ *              Note that this is a pretty bad scenario if it ever
+ *              happens.  The code I have added should allow us to
+ *              handle the situation under all but the worst conditions, 
+ *              but one can argue that I should just scream and die if I 
+ *              ever detect the condidtion.
+ *
  *-------------------------------------------------------------------------
  */
 
@@ -9933,7 +10728,10 @@ H5C_make_space_in_cache(H5F_t *	f,
 #if H5C_MAINTAIN_CLEAN_AND_DIRTY_LRU_LISTS
     size_t		empty_space;
 #endif /* H5C_MAINTAIN_CLEAN_AND_DIRTY_LRU_LISTS */
+    hbool_t             prev_is_dirty = FALSE;
+    hbool_t             entry_is_epoch_maker = FALSE;
     H5C_cache_entry_t *	entry_ptr;
+    H5C_cache_entry_t *	next_ptr;
     H5C_cache_entry_t *	prev_ptr;
 
     FUNC_ENTER_NOAPI_NOINIT(H5C_make_space_in_cache)
@@ -9962,10 +10760,18 @@ H5C_make_space_in_cache(H5F_t *	f,
             HDassert( ! (entry_ptr->is_read_only) );
             HDassert( (entry_ptr->ro_ref_count) == 0 );
 
-            prev_ptr = entry_ptr->prev;
+            next_ptr = entry_ptr->next;
+	    prev_ptr = entry_ptr->prev;
+
+	    if ( prev_ptr != NULL ) {
+
+                prev_is_dirty = prev_ptr->is_dirty;
+            }
 
             if ( (entry_ptr->type)->id != H5C__EPOCH_MARKER_TYPE ) {
 
+                entry_is_epoch_maker = FALSE;
+
                 if ( entry_ptr->is_dirty ) {
 
                     result = H5C_flush_single_entry(f,
@@ -9994,6 +10800,7 @@ H5C_make_space_in_cache(H5F_t *	f,
                 /* Skip epoch markers.  Set result to SUCCEED to avoid
                  * triggering the error code below.
                  */
+                entry_is_epoch_maker = TRUE;
                 result = SUCCEED;
             }
 
@@ -10003,11 +10810,54 @@ H5C_make_space_in_cache(H5F_t *	f,
                             "unable to flush entry")
             }
 
-            entry_ptr = prev_ptr;
-        }
+            if ( prev_ptr != NULL ) {
+#ifndef NDEBUG
+                if ( prev_ptr->magic != H5C__H5C_CACHE_ENTRY_T_MAGIC ) {
+
+                    /* something horrible has happened to *prev_ptr --
+                     * scream and die.
+                     */
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                "*prev_ptr corrupt 1")
+
+                }
+#endif /* NDEBUG */
+		if ( entry_is_epoch_maker ) {
+	
+		    entry_ptr = prev_ptr;
+
+		} else if ( ( prev_ptr->is_dirty != prev_is_dirty )
+                            ||
+                            ( prev_ptr->next != next_ptr )
+                            ||
+                            ( prev_ptr->is_protected )
+                            ||
+                            ( prev_ptr->is_pinned ) ) {
+
+                    /* something has happened to the LRU -- start over
+                     * from the tail.
+                     */
+
+                    entry_ptr = cache_ptr->LRU_tail_ptr;
+
+                } else {
+
+                    entry_ptr = prev_ptr;
+
+                }
+            } else {
+
+                entry_ptr = NULL;
+
+            }
+
+            entries_examined++;
+
+	}
 
 #if H5C_MAINTAIN_CLEAN_AND_DIRTY_LRU_LISTS
 
+	entries_examined = 0;
         initial_list_len = cache_ptr->dLRU_list_len;
         entry_ptr = cache_ptr->dLRU_tail_ptr;
 
@@ -10034,6 +10884,13 @@ H5C_make_space_in_cache(H5F_t *	f,
 
             prev_ptr = entry_ptr->aux_prev;
 
+	    next_ptr = entry_ptr->aux_next;
+
+            if ( prev_ptr != NULL ) {
+
+                HDassert( prev_ptr->is_dirty );
+            }
+
             result = H5C_flush_single_entry(f,
                                             primary_dxpl_id,
                                             secondary_dxpl_id,
@@ -10050,7 +10907,66 @@ H5C_make_space_in_cache(H5F_t *	f,
                             "unable to flush entry")
             }
 
-            entry_ptr = prev_ptr;
+            if ( prev_ptr != NULL ) {
+#ifndef NDEBUG
+                if (prev_ptr->magic != H5C__H5C_CACHE_ENTRY_T_MAGIC) {
+
+                    /* something horrible has happened to *prev_ptr --
+                     * scream and die.
+                     */
+
+                    HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, \
+                                "*prev_ptr corrupt 2")
+
+                } else 
+#endif /* #ifndef NDEBUG */
+		if ( ( ! ( prev_ptr->is_dirty ) )
+                     ||
+                     ( prev_ptr->aux_next != next_ptr )
+                     ||
+                     ( prev_ptr->is_protected )
+                     ||
+                     ( prev_ptr->is_pinned ) ) {
+
+                    /* something has happened to the dirty LRU -- start over
+                     * from the tail.
+                     */
+
+#if 0 /* This debuging code may be useful in the future -- keep it for now. */
+                    if ( ! ( prev_ptr->is_dirty ) ) {
+                        HDfprintf(stdout, "%s: ! prev_ptr->is_dirty\n",
+                                  fcn_name);
+                    }
+                    if ( prev_ptr->aux_next != next_ptr ) {
+                        HDfprintf(stdout, "%s: prev_ptr->next != next_ptr\n",
+                                  fcn_name);
+                    }
+                    if ( prev_ptr->is_protected ) {
+                        HDfprintf(stdout, "%s: prev_ptr->is_protected\n",
+                                  fcn_name);
+                    }
+                    if ( prev_ptr->is_pinned ) {
+                        HDfprintf(stdout, "%s:prev_ptr->is_pinned\n",
+                                  fcn_name);
+                    }
+
+                    HDfprintf(stdout, "%s: re-starting scan of dirty list\n",
+                              fcn_name);
+#endif /* JRM */
+                    entry_ptr = cache_ptr->dLRU_tail_ptr;
+
+                } else {
+
+                    entry_ptr = prev_ptr;
+
+                }
+            } else {
+
+                entry_ptr = NULL;
+
+            }
+
+            entries_examined++;
         }
 
 #endif /* H5C_MAINTAIN_CLEAN_AND_DIRTY_LRU_LISTS */
@@ -10096,6 +11012,7 @@ H5C_make_space_in_cache(H5F_t *	f,
             }
 
             entry_ptr = prev_ptr;
+	    entries_examined++;
         }
     }