Initial checkin of page buffer re-implementation to support VFD SWMR.

Tested serial / debug on Charis and Jelly.

Two known issues:

1) New page buffer seems to expose issues in the accumulator code.

   For whatever reason, fheap with the new page buffer exposes corruption
   issues if the page buffer uses H5F__accum_read/write(), but the problems
   go away if the page buffers uses H5FD_read/write() instead.

   Need to either chase this or dis-able page bufffer in combination with
   the accumulator.

2) Encountered a number of assertion failures that are explainable by the
   free space manager code not telling the page buffer to discard pages
   when they are freed.

   Wrote code to handle this -- once the free space manager is modified,
   this code should be removed and the original assertions restored.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 3760c41..9e523de 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -295,7 +295,9 @@ struct H5F_file_t {
     unsigned long feature_flags; /* VFL Driver feature Flags            */
     haddr_t	maxaddr;	/* Maximum address for file             */
 
-    H5PB_t      *page_buf;                  /* The page buffer cache                */
+    H5PB_t      *pb_ptr;        /* pointer to the page buffer, or NULL  */
+                                /* if the page buffer is disabled.      */
+
     H5AC_t      *cache;		/* The object cache	 		*/
     H5AC_cache_config_t
 		mdc_initCacheCfg; /* initial configuration for the      */