gpu: drm: drm_vm: Adding new typedef vm_fault_t

Use new return type vm_fault_t for fault handler. For
now, this is just documenting that the function returns
a VM_FAULT value rather than an errno. Once all instances
are converted, vm_fault_t will become a distinct type.

commit 1c8f422059ae ("mm: change return type to vm_fault_t")

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180510134203.GA25166@jordon-HP-15-Notebook-PC

drivers/gpu/drm/drm_vm.c

@@ -100,7 +100,7 @@ static pgprot_t drm_dma_prot(uint32_t map_type, struct vm_area_struct *vma)
  * map, get the page, increment the use count and return it.
  */
 #if IS_ENABLED(CONFIG_AGP)
-static int drm_vm_fault(struct vm_fault *vmf)
+static vm_fault_t drm_vm_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_file *priv = vma->vm_file->private_data;
@@ -173,7 +173,7 @@ vm_fault_error:
 	return VM_FAULT_SIGBUS;	/* Disallow mremap */
 }
 #else
-static int drm_vm_fault(struct vm_fault *vmf)
+static vm_fault_t drm_vm_fault(struct vm_fault *vmf)
 {
 	return VM_FAULT_SIGBUS;
 }
@@ -189,7 +189,7 @@ static int drm_vm_fault(struct vm_fault *vmf)
  * Get the mapping, find the real physical page to map, get the page, and
  * return it.
  */
-static int drm_vm_shm_fault(struct vm_fault *vmf)
+static vm_fault_t drm_vm_shm_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_local_map *map = vma->vm_private_data;
@@ -291,7 +291,7 @@ static void drm_vm_shm_close(struct vm_area_struct *vma)
  *
  * Determine the page number from the page offset and get it from drm_device_dma::pagelist.
  */
-static int drm_vm_dma_fault(struct vm_fault *vmf)
+static vm_fault_t drm_vm_dma_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_file *priv = vma->vm_file->private_data;
@@ -326,7 +326,7 @@ static int drm_vm_dma_fault(struct vm_fault *vmf)
  *
  * Determine the map offset from the page offset and get it from drm_sg_mem::pagelist.
  */
-static int drm_vm_sg_fault(struct vm_fault *vmf)
+static vm_fault_t drm_vm_sg_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct drm_local_map *map = vma->vm_private_data;