.

include/wendelin/bigfile/file.h

@@ -73,8 +73,33 @@ struct bigfile_ops {
      */
     int  (*storeblk) (BigFile *file, blk_t blk, const void *buf);
 
+    /* release is called to release resources associated with file.
+     *
+     * The file is not otherwise used at the time of and past release call.
+     */
+    void (*release)  (BigFile *file);
 
-    // XXX picture of base layer + RW pages
+
+    // Overlaying
+    //
+    // XXX text
+
+    // wc mmap =
+    //
+    //                  ┌──┐                      ┌──┐
+    //                  │RW│                      │RW│      ← dirty
+    //                  └──┘                      └──┘
+    //                            +
+    //      ─────────────────────────────────────────────   ← base
+    //
+    // base = file view @ zconn.at  =>
+    // base =
+    //                                           ___        /@revA/bigfile/X
+    //         __                                           /@revB/bigfile/X
+    //                _                                     /@revC/bigfile/X
+    //                            +                         ...
+    //      ───  ───── ──────────────────────────   ─────   /head/bigfile/X
+    //
     // XXX link to wcfs/client/wcfs.h
 
     // - mmap_setup_read(vma, file[blk +blklen)) -> addr    setup initial read-only mmap to serve vma
@@ -97,8 +122,9 @@ struct bigfile_ops {
      *      // backend detects that block is changed from outside
      *      // fileh is vma->fileh - file handle with which the vma is associated
      *      virt_lock()
-     *      if (!fileh_blk_isdirty(fileh, blk)) {   XXX -> __fileh_page_isdirty(fileh, pgoff)
-     *          // update mappings for all fileh's vma that cover blk
+     *      for (pgoff : page_offsets_covered_by(blk))
+     *          if (!__fileh_page_isdirty(fileh, pgoff)) {
+     *              // update mappings for all fileh's vma that cover pgoff
      *          }
      *      virt_unlock()
      *
@@ -127,13 +153,6 @@ struct bigfile_ops {
      * Must not fail.
      */
     void (*munmap) (VMA *vma, BigFile *file);
-
-
-    /* release is called to release resources associated with file.
-     *
-     * The file is not otherwise used at the time of and past release call.
-     */
-    void (*release)  (BigFile *file);
 };
 typedef struct bigfile_ops bigfile_ops;