xen/grant-table: Add an helper to iterate over a specific number of grants

[cascardo/linux.git] / drivers / xen / grant-table.c

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 72d6339..c49f79e 100644 (file)
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -802,6 +802,28 @@ void gnttab_foreach_grant_in_range(struct page *page,
 }
 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
 
+void gnttab_foreach_grant(struct page **pages,
+                         unsigned int nr_grefs,
+                         xen_grant_fn_t fn,
+                         void *data)
+{
+       unsigned int goffset = 0;
+       unsigned long xen_pfn = 0;
+       unsigned int i;
+
+       for (i = 0; i < nr_grefs; i++) {
+               if ((i % XEN_PFN_PER_PAGE) == 0) {
+                       xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
+                       goffset = 0;
+               }
+
+               fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
+
+               goffset += XEN_PAGE_SIZE;
+               xen_pfn++;
+       }
+}
+
 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                    struct gnttab_map_grant_ref *kmap_ops,
                    struct page **pages, unsigned int count)