mm: Introduce new type vm_fault_t

We have introduce a new return type vm_fault_t for
fault, page_mkwrite and pfn_mkwrite handlers. Update
the document for the same
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/Locking

@@ -532,9 +532,9 @@ More details about quota locking can be found in fs/dquot.c.
 prototypes:
 	void (*open)(struct vm_area_struct*);
 	void (*close)(struct vm_area_struct*);
-	int (*fault)(struct vm_area_struct*, struct vm_fault *);
-	int (*page_mkwrite)(struct vm_area_struct *, struct vm_fault *);
-	int (*pfn_mkwrite)(struct vm_area_struct *, struct vm_fault *);
+	vm_fault_t (*fault)(struct vm_area_struct*, struct vm_fault *);
+	vm_fault_t (*page_mkwrite)(struct vm_area_struct *, struct vm_fault *);
+	vm_fault_t (*pfn_mkwrite)(struct vm_area_struct *, struct vm_fault *);
 	int (*access)(struct vm_area_struct *, unsigned long, void*, int, int);
 
 locking rules: