1 files changed, 63 insertions, 35 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index b1202cf81f4b..ced5efcdd4b6 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -640,11 +640,10 @@ static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 {
 	struct address_space *mapping = NULL;
 
-	if (vma->vm_file)
+	if (vma->vm_file) {
 		mapping = vma->vm_file->f_mapping;
-
-	if (mapping)
 		mutex_lock(&mapping->i_mmap_mutex);
+	}
 
 	__vma_link(mm, vma, prev, rb_link, rb_parent);
 	__vma_link_file(vma);
@@ -2872,6 +2871,31 @@ int may_expand_vm(struct mm_struct *mm, unsigned long npages)
 	return 1;
 }
 
+static int special_mapping_fault(struct vm_area_struct *vma,
+				 struct vm_fault *vmf);
+
+/*
+ * Having a close hook prevents vma merging regardless of flags.
+ */
+static void special_mapping_close(struct vm_area_struct *vma)
+{
+}
+
+static const char *special_mapping_name(struct vm_area_struct *vma)
+{
+	return ((struct vm_special_mapping *)vma->vm_private_data)->name;
+}
+
+static const struct vm_operations_struct special_mapping_vmops = {
+	.close = special_mapping_close,
+	.fault = special_mapping_fault,
+	.name = special_mapping_name,
+};
+
+static const struct vm_operations_struct legacy_special_mapping_vmops = {
+	.close = special_mapping_close,
+	.fault = special_mapping_fault,
+};
 
 static int special_mapping_fault(struct vm_area_struct *vma,
 				struct vm_fault *vmf)
@@ -2887,7 +2911,13 @@ static int special_mapping_fault(struct vm_area_struct *vma,
 	 */
 	pgoff = vmf->pgoff - vma->vm_pgoff;
 
-	for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
+	if (vma->vm_ops == &legacy_special_mapping_vmops)
+		pages = vma->vm_private_data;
+	else
+		pages = ((struct vm_special_mapping *)vma->vm_private_data)->
+			pages;
+
+	for (; pgoff && *pages; ++pages)
 		pgoff--;
 
 	if (*pages) {
@@ -2900,30 +2930,11 @@ static int special_mapping_fault(struct vm_area_struct *vma,
 	return VM_FAULT_SIGBUS;
 }
 
-/*
- * Having a close hook prevents vma merging regardless of flags.
- */
-static void special_mapping_close(struct vm_area_struct *vma)
-{
-}
-
-static const struct vm_operations_struct special_mapping_vmops = {
-	.close = special_mapping_close,
-	.fault = special_mapping_fault,
-};
-
-/*
- * Called with mm->mmap_sem held for writing.
- * Insert a new vma covering the given region, with the given flags.
- * Its pages are supplied by the given array of struct page *.
- * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
- * The region past the last page supplied will always produce SIGBUS.
- * The array pointer and the pages it points to are assumed to stay alive
- * for as long as this mapping might exist.
- */
-struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
-			    unsigned long addr, unsigned long len,
-			    unsigned long vm_flags, struct page **pages)
+static struct vm_area_struct *__install_special_mapping(
+	struct mm_struct *mm,
+	unsigned long addr, unsigned long len,
+	unsigned long vm_flags, const struct vm_operations_struct *ops,
+	void *priv)
 {
 	int ret;
 	struct vm_area_struct *vma;
@@ -2940,8 +2951,8 @@ struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
 	vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
-	vma->vm_ops = &special_mapping_vmops;
-	vma->vm_private_data = pages;
+	vma->vm_ops = ops;
+	vma->vm_private_data = priv;
 
 	ret = insert_vm_struct(mm, vma);
 	if (ret)
@@ -2958,16 +2969,33 @@ out:
 	return ERR_PTR(ret);
 }
 
+/*
+ * Called with mm->mmap_sem held for writing.
+ * Insert a new vma covering the given region, with the given flags.
+ * Its pages are supplied by the given array of struct page *.
+ * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
+ * The region past the last page supplied will always produce SIGBUS.
+ * The array pointer and the pages it points to are assumed to stay alive
+ * for as long as this mapping might exist.
+ */
+struct vm_area_struct *_install_special_mapping(
+	struct mm_struct *mm,
+	unsigned long addr, unsigned long len,
+	unsigned long vm_flags, const struct vm_special_mapping *spec)
+{
+	return __install_special_mapping(mm, addr, len, vm_flags,
+					 &special_mapping_vmops, (void *)spec);
+}
+
 int install_special_mapping(struct mm_struct *mm,
 			    unsigned long addr, unsigned long len,
 			    unsigned long vm_flags, struct page **pages)
 {
-	struct vm_area_struct *vma = _install_special_mapping(mm,
-			    addr, len, vm_flags, pages);
+	struct vm_area_struct *vma = __install_special_mapping(
+		mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
+		(void *)pages);
 
-	if (IS_ERR(vma))
-		return PTR_ERR(vma);
-	return 0;
+	return PTR_ERR_OR_ZERO(vma);
 }
 
 static DEFINE_MUTEX(mm_all_locks_mutex);