more

core/mem/vmo.c

@@ -1,9 +1,9 @@
 #include <zinnia/alloc.h>
 #include <zinnia/errno.h>
 #include <zinnia/list.h>
+#include <zinnia/string.h>
 #include <zinnia/utils.h>
 #include <zinnia/vmo.h>
-#include <zinnia/string.h>
 
 void vmo_ref(struct vmo* obj) {
     refcount_inc(&obj->rc);
@@ -211,6 +211,25 @@ errno_t vmo_new_phys(struct paged_vmo** out) {
     return vmo_new_paged(phys_pager, out);
 }
 
+void vmo_truncate_paged(struct paged_vmo* paged, size_t length) {
+    const size_t page_size = arch_mem_page_size();
+    const size_t keep_pages = ROUND_UP(length, page_size) / page_size;
+
+    spin_lock(&paged->lock);
+    struct page_list** pp = &list_first(&paged->cache);
+    while (*pp) {
+        struct page_list* entry = *pp;
+        if (entry->offset >= keep_pages) {
+            *pp = list_next(entry, next);
+            paged->source.put_page(&paged->source, entry->offset, entry->value);
+            mem_free(entry);
+        } else {
+            pp = &list_next(entry, next);
+        }
+    }
+    spin_unlock(&paged->lock);
+}
+
 struct phys_range_vmo {
     struct vmo object;
     uintptr_t start;