.

bigfile/_bigfile.c

@@ -1031,7 +1031,7 @@ static PyMemberDef pyfile_members[] = {
 
 static /*const*/ PyMethodDef pyfile_methods[] = {
     // XXX should be separate BigFileH ctor or fileh_open function?
-    {"fileh_open",  pyfileh_open,   METH_VARARGS,   "fileh_open(ram=None) -> new file handle"},
+    {"fileh_open",  pyfileh_open,   METH_VARARGS,   "fileh_open(ram=None, mmap_overlay=None) -> new file handle"},
     {NULL}
 };
 

bigfile/file_zodb.py

@@ -665,7 +665,8 @@ class _ZBigFileH(object):
         if wcfileh is not None:
             self.zfileh = wcfileh
         else:
-            self.zfileh = zfile._v_file.fileh_open()
+            # XXX
+            self.zfileh = zfile._v_file.fileh_open(mmap_overlay=_use_wcfs)
 
         # FIXME zfile._p_jar could be None (ex. ZBigFile is newly created
         #       before first commit)

bigfile/tests/bench_virtmem.c

@@ -80,7 +80,7 @@ void bench_pagefault() {
     };
 
     /* setup f mapping */
-    err = fileh_open(fh, &f, ram);
+    err = fileh_open(fh, &f, ram, DONT_MMAP_OVERLAY);
     ok1(!err);
 
     err = fileh_mmap(vma, fh, 0, npage);

bigfile/tests/test_virtmem.c

@@ -393,7 +393,7 @@ void test_file_access_synthetic(void)
         .file_ops   = &x_ops,
     };
 
-    err = fileh_open(fh, &fileid, ram);
+    err = fileh_open(fh, &fileid, ram, DONT_MMAP_OVERLAY);
     ok1(!err);
     ok1(list_empty(&fh->mmaps));
 
@@ -956,7 +956,7 @@ void test_file_access_pagefault()
         .file_ops   = &fileid_ops,
     };
 
-    err = fileh_open(fh, &fileid, ram);
+    err = fileh_open(fh, &fileid, ram, DONT_MMAP_OVERLAY);
     ok1(!err);
 
 /* implicitly use fileh=fh */
@@ -1084,7 +1084,7 @@ void test_pagefault_savestate()
         .file_ops   = &badfile_ops,
     };
 
-    err = fileh_open(fh, &f, ram);
+    err = fileh_open(fh, &f, ram, DONT_MMAP_OVERLAY);
     ok1(!err);
 
     err = fileh_mmap(vma, fh, 0, 1);
@@ -1266,7 +1266,7 @@ void test_file_access_mmapbase(void)
     fstore(103, 103);
 
 
-    err = fileh_open(fh, &file, ram);
+    err = fileh_open(fh, &file, ram, MMAP_OVERLAY);
     ok1(!err);
 
 /* implicitly use fileh=fh */

bigfile/virtmem.c

@@ -146,10 +146,26 @@ static void sigsegv_restore(const sigset_t *save_sigset)
  * OPEN / CLOSE *
  ****************/
 
-int fileh_open(BigFileH *fileh, BigFile *file, RAM *ram)
+int fileh_open(BigFileH *fileh, BigFile *file, RAM *ram, FileHOpenFlags flags)
 {
     int err = 0;
     sigset_t save_sigset;
+    const bigfile_ops *fops = file->file_ops;
+
+    if (!(flags == 0 || flags == MMAP_OVERLAY || flags == DONT_MMAP_OVERLAY))
+        return -EINVAL;
+    if (flags == 0) {
+        flags = fops->mmap_setup_read ? MMAP_OVERLAY : DONT_MMAP_OVERLAY;
+    }
+    if (flags & MMAP_OVERLAY && flags & DONT_MMAP_OVERLAY)
+        return -EINVAL;
+    if (flags == MMAP_OVERLAY) {
+        ASSERT(fops->mmap_setup_read);
+        ASSERT(fops->remmap_blk_read);
+    }
+    if (flags == DONT_MMAP_OVERLAY) {
+        ASSERT(fops->loadblk);
+    }
 
     sigsegv_block(&save_sigset);
     virt_lock();
@@ -167,8 +183,7 @@ int fileh_open(BigFileH *fileh, BigFile *file, RAM *ram)
     fileh->writeout_inprogress = 0;
     pagemap_init(&fileh->pagemap, ilog2_exact(ram->pagesize));
 
-    // XXX hardcoded - allow user choice?
-    fileh->mmap_overlay = (file->file_ops->mmap_setup_read != NULL);
+    fileh->mmap_overlay = (flags == MMAP_OVERLAY);
 
 out:
     virt_unlock();

include/wendelin/bigfile/virtmem.h

@@ -156,19 +156,34 @@ struct VMA {
  *      API for clients      *
  *****************************/
 
+/* flags for fileh_open */
+enum FileHOpenFlags {
+    /* use "mmap overlay" mode for base file data of all mappings created
+     * for this fileh.
+     *
+     * The file must have .mmap_setup_read & friends != NULL in file_ops.
+     */
+    MMAP_OVERLAY        = 1 << 0,
+
+    /* don't use "mmap overlay" mode */
+    DONT_MMAP_OVERLAY   = 1 << 1,
+
+    /* NOTE: if both MMAP_OVERLAY and DONT_MMAP_OVERLAY are not given,
+     * the behaviour is to use mmap overlay if .mmap_* fops != NULL and
+     * regular loads otherwise. */
+};
+typedef enum FileHOpenFlags FileHOpenFlags;
+
 /* open handle for a BigFile
  *
  * @fileh[out]  BigFileH handle to initialize for this open
  * @file
  * @ram         RAM that will back created fileh mappings
+ * @flags       flags for this open - see FileHOpenFlags
  *
  * @return  0 - ok, !0 - fail
  */
-int fileh_open(BigFileH *fileh, BigFile *file, RAM *ram);
-
-// XXX + fileh_open_overlay(fileh, file, base, ram) ?
-// here base is glued data from head/bigfile/file + revX/bigfile/file overwrites.
-// file will be used only to storeblk (loadblk=BUG).
+int fileh_open(BigFileH *fileh, BigFile *file, RAM *ram, FileHOpenFlags flags);
 
 
 /* close fileh