.

Makefile

@@ -96,7 +96,8 @@ LINKC	= $(LINK.c) $< $(LOADLIBES) $(LDLIBS) -o $@
 # tests without instrumentation
 test.t	: $(TESTS:%=%.trun)
 %.trun	: %.t
-	gdb -q -ex run -ex backtrace -ex quit $(XRUN<)
+	#gdb -q -ex run -ex backtrace -ex quit $(XRUN<)
+	$(XRUN<)
 
 %.t	: %.c $(ccan_config)
 	$(LINKC)

bigfile/tests/test_virtmem.c

@@ -1179,11 +1179,15 @@ void test_file_access_mmapbase(void)
     RAM *ram;
     BigFileH fh_struct, *fh = &fh_struct;
     VMA vma_struct, *vma = &vma_struct;
+    Page *page0, *page2, *page3;
     size_t PS, PSb;
     int fd, err;
 
     diag("Testing file access (mmap base)");
 
+    // XXX save/restore sigaction ?
+    ok1(!pagefault_init());
+
     ram = ram_new(NULL, NULL);
     ok1(ram);
     PS = ram->pagesize;
@@ -1243,6 +1247,7 @@ void test_file_access_mmapbase(void)
     ok1(!M(vma, 3));    CHECK_NOPAGE(       103                      );
 
     ok1(list_empty(&ram->lru_list));
+    ok1(list_empty(&fh->dirty_pages));
 
     /* read page[0] - served from base mmap and no RAM page is loaded */
     ok1(B(vma, 0*PSb) == 100);
@@ -1251,6 +1256,22 @@ void test_file_access_mmapbase(void)
     ok1(!M(vma, 1));    CHECK_NOPAGE(       101                      );
     ok1(!M(vma, 2));    CHECK_NOPAGE(       102                      );
     ok1(!M(vma, 3));    CHECK_NOPAGE(       103                      );
+
+    ok1(list_empty(&ram->lru_list));
+    ok1(list_empty(&fh->dirty_pages));
+
+
+    /* write to page[2] = XXX */
+    B(vma, 2*PSb) = 12;
+
+    page2 = pagemap_get(&fh->pagemap, 102);
+    ok1(!M(vma, 0));    CHECK_NOPAGE(         100                      );
+    ok1(!M(vma, 1));    CHECK_NOPAGE(         101                      );
+    ok1( M(vma, 2));    CHECK_PAGE  (page2,   102,    PAGE_DIRTY,     1);
+    ok1(!M(vma, 3));    CHECK_NOPAGE(         103                      );
+
+    ok1(ram->lru_list.prev == &page2->lru);
+    ok1(page2->lru.prev == &ram->lru_list);
 }
 
 

bigfile/virtmem.c

@@ -615,7 +615,9 @@ VMFaultResult vma_on_pagefault(VMA *vma, uintptr_t addr, int write)
 
     /* continuing on_pagefault() - see (1) there ... */
 
-    // XXX overlay: assert write
+    /* wcfs: we should get into SIGSEGV handler only on write access */
+    if (vma->mmap_overlay)
+        BUG_ON(!write);
 
     /* (2) vma, addr -> fileh, pagen    ;idx of fileh page covering addr */
     fileh = vma->fileh;
@@ -624,7 +626,12 @@ VMFaultResult vma_on_pagefault(VMA *vma, uintptr_t addr, int write)
     /* (3) fileh, pagen -> page  (via pagemap) */
     page = pagemap_get(&fileh->pagemap, pagen);
 
-    // XXX overlay: assert !page
+    /* wcfs: all dirty pages are mmapped when vma is created */
+    // FIXME no: it could be in PAGE_LOADING state
+    // XXX and after VM_RETRY it could be in PAGE_LOADED state
+    // XXX ----//----                        even for write
+    if (vma->mmap_overlay)
+        BUG_ON(page);
 
     /* (4) no page found - allocate new from ram */
     while (!page) {
@@ -697,7 +704,7 @@ VMFaultResult vma_on_pagefault(VMA *vma, uintptr_t addr, int write)
         // XXX overlay: copy data from base image, page.state=DIRTY
         // XXX overlay: goto inject_page
 
-        /* loadblk() -> pageram memory */
+        /* load block -> pageram memory */
         blk = page->f_pgoffset;     // NOTE because blksize = pagesize
 
         /* mark page as loading and unlock virtmem before calling loadblk()
@@ -709,15 +716,23 @@ VMFaultResult vma_on_pagefault(VMA *vma, uintptr_t addr, int write)
         page->state = PAGE_LOADING;
         virt_unlock();
 
-        err = file->file_ops->loadblk(file, blk, pageram);
+        if (vma->mmap_overlay) {
+            /* wcfs: copy block data from read-only base mmap.
+             * NOTE we'll get SIGBUG here if wcfs returns EIO when loading block data */
+            memcpy(pageram, vma_page_addr(vma, page), page_size(page));
+        }
+        else {
+            /* !wcfs: call loadblk */
+            err = file->file_ops->loadblk(file, blk, pageram);
 
-        /* TODO on error -> try to throw exception somehow to the caller, so
-         *      that it can abort current transaction, but not die.
-         *
-         * NOTE for analogue situation when read for mmaped file fails, the
-         *      kernel sends SIGBUS
-         */
-        TODO (err);
+            /* TODO on error -> try to throw exception somehow to the caller, so
+             *      that it can abort current transaction, but not die.
+             *
+             * NOTE for analogue situation when read for mmaped file fails, the
+             *      kernel sends SIGBUS
+             */
+            TODO (err);
+        }
 
         /* relock virtmem */
         virt_lock();