.

bigfile/tests/test_virtmem.c

@@ -1127,15 +1127,12 @@ struct BigFileMMap {
 };
 typedef struct BigFileMMap BigFileMMap;
 
-void *mmapfile_mmap_setup_read(BigFile *file, blk_t blk, size_t blklen, VMA *vma) {
+void mmapfile_release(BigFile *file) {
     BigFileMMap *f = upcast(BigFileMMap*, file);
-    void *addr;
-
-    addr = mmap(NULL, blklen*f->blksize, PROT_READ, MAP_SHARED, f->fd, blk*f->blksize);
-    if (addr == MAP_FAILED)
-        addr = NULL;
+    int err;
 
-    return addr;
+    err = close(f->fd);
+    BUG_ON(err);
 }
 
 int mmapfile_storeblk(BigFile *file, blk_t blk, const void *buf) {
@@ -1157,17 +1154,37 @@ int mmapfile_storeblk(BigFile *file, blk_t blk, const void *buf) {
     return 0;
 }
 
-void mmapfile_release(BigFile *file) {
+void *mmapfile_mmap_setup_read(BigFile *file, blk_t blk, size_t blklen, VMA *vma) {
     BigFileMMap *f = upcast(BigFileMMap*, file);
-    int err;
+    void *addr;
 
-    err = close(f->fd);
-    BUG_ON(err);
+    addr = mmap(NULL, blklen*f->blksize, PROT_READ, MAP_SHARED, f->fd, blk*f->blksize);
+    if (addr == MAP_FAILED)
+        addr = NULL;
+
+    return addr;
+}
+
+int mmapfile_remmap_blk_read(BigFile *file, blk_t blk, VMA *vma) {
+    BigFileMMap *f = upcast(BigFileMMap*, file);
+    TODO (f->blksize != vma->fileh->ramh->ram->pagesize);
+    ASSERT(vma->f_pgoffset <= blk && blk < vma_addr_fpgoffset(vma, vma->addr_stop));
+    pgoff_t pgoff_invma = blk - vma->f_pgoffset;
+    uintptr_t addr = vma->addr_start + pgoff_invma*f->blksize;
+    void *mapped;
+
+    mapped = mmap((void *)addr, 1*f->blksize, PROT_READ, MAP_SHARED | MAP_FIXED, f->fd, blk*f->blksize);
+    if (mapped == MAP_FAILED)
+        return -1;
+
+    ASSERT(mapped == (void *)addr);
+    return 0;
 }
 
 static const struct bigfile_ops mmapfile_ops = {
     .loadblk            = NULL,
     .mmap_setup_read    = mmapfile_mmap_setup_read,
+    .remmap_blk_read    = mmapfile_remmap_blk_read,
     .storeblk           = mmapfile_storeblk,
     .release            = mmapfile_release,
 };

bigfile/virtmem.c

@@ -1068,7 +1068,7 @@ static void vma_page_ensure_unmapped(VMA *vma, Page *page)
         int err;
 
         TODO (file->blksize != page_size(page));
-        err = file->file_ops->remmap_blk_read(file, page->f_pgoffset /* =blk */, vma);
+        err = file->file_ops->remmap_blk_read(file, /* blk = */page->f_pgoffset, vma);
         BUG_ON(err); /* must not fail */
     }
     else {