.

bigfile/file_zodb.py

@@ -596,6 +596,19 @@ class ZBigFile(LivePersistent):
     # invalidate data   .blktab[blk] invalidated -> invalidate page
     def invalidateblk(self, blk):
         for fileh in self._v_filehset:
+            # wcfs: there is no need to propagate ZODB -> fileh invalidation by
+            # client since WCFS handles invalidations from ZODB by itself.
+            #
+            # More: the algorythm to compute δ(ZODB) -> δ(blk) is more complex
+            # than 1-1 ZBlk <-> blk mapping: ZBlk could stay constant, but if
+            # ZBigFile.blktab topology is changed, affected file blocks have to
+            # be invalidated. Currently both !wcfs and wcfs codepaths fail to
+            # handle that, but wcfs will be improved and !wcfs will be deprecated.
+            #
+            # -> don't propagate ZODB -> WCFS invalidation by client to fully
+            # rely on and test wcfs subsystem.
+            if fileh.uses_mmap_overlay():
+                continue
             fileh.invalidate_page(blk)  # XXX assumes blksize == pagesize
 
 

bigfile/tests/test_virtmem.c

@@ -1633,7 +1633,7 @@ void test_file_access_mmapoverlay(void)
     ok1(!M(vma, 2));    CHECK_NOPAGE(       102                      );
     ok1(!M(vma, 3));    CHECK_NOPAGE(       103                      );
 
-    // XXX invalidation ?
+    /* no invalidation - fileh_invalidate_page is forbidden for "mmap overlay" mode */
 
 
     /* free resources */

bigfile/virtmem.c

@@ -551,9 +551,15 @@ void fileh_invalidate_page(BigFileH *fileh, pgoff_t pgoffset)
 
     /* it's an error to invalidate fileh while writeout is in progress */
     BUG_ON(fileh->writeout_inprogress);
-    // XXX wcfs: invalidate_page must not be called (wcfs handles invalidations itself)
-    // XXX       or allow invalidate anyway (e.g. DIRTY -> base) ?
-    // XXX yes -> allow invalidate for wcfs too - means forget in-ram page and mmap to base memory
+
+    /* wcfs: even though the operation to invalidate a page is well defined (it
+     * is subset of discard), we forbid it since wcfs handles invalidations
+     * from ZODB by itself inside wcfs server.
+     *
+     * It was kind of mistake to expose in 92bfd03e (bigfile: ZODB -> BigFileH
+     * invalidate propagation) fileh_invalidate_page as public API, since such
+     * invalidation should be handled by a BigFile instance internally. */
+    BUG_ON(fileh->mmap_overlay);
 
     page = pagemap_get(&fileh->pagemap, pgoffset);
     if (page) {

include/wendelin/bigfile/virtmem.h

@@ -320,7 +320,7 @@ VIRTMEM_API void fileh_dirty_discard(BigFileH *fileh);
  *   file was changed externally )
  *
  * it's an error to call fileh_invalidate_page() while writeout for fileh is in
- * progress.
+ * progress, or for fileh opened in MMAP_OVERLAY mode.
  */
 VIRTMEM_API void fileh_invalidate_page(BigFileH *fileh, pgoff_t pgoffset);