drm/i915: remove writeback hook

Ditch the writeback hook and drop i915_gem_object_writeback(). We
already support the shrinker_release_pages hook which can just call
shmem_writeback directly.
Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211215110746.865-1-matthew.auld@intel.com

drivers/gpu/drm/i915/gem/i915_gem_object.h

@@ -459,7 +459,6 @@ i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
 
 int __i915_gem_object_put_pages(struct drm_i915_gem_object *obj);
 int i915_gem_object_truncate(struct drm_i915_gem_object *obj);
-void i915_gem_object_writeback(struct drm_i915_gem_object *obj);
 
 /**
  * i915_gem_object_pin_map - return a contiguous mapping of the entire object

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

@@ -57,7 +57,6 @@ struct drm_i915_gem_object_ops {
 	void (*put_pages)(struct drm_i915_gem_object *obj,
 			  struct sg_table *pages);
 	int (*truncate)(struct drm_i915_gem_object *obj);
-	void (*writeback)(struct drm_i915_gem_object *obj);
 	int (*shrinker_release_pages)(struct drm_i915_gem_object *obj,
 				      bool no_gpu_wait,
 				      bool should_writeback);

drivers/gpu/drm/i915/gem/i915_gem_pages.c

@@ -168,16 +168,6 @@ int i915_gem_object_truncate(struct drm_i915_gem_object *obj)
 	return 0;
 }
 
-/* Try to discard unwanted pages */
-void i915_gem_object_writeback(struct drm_i915_gem_object *obj)
-{
-	assert_object_held_shared(obj);
-	GEM_BUG_ON(i915_gem_object_has_pages(obj));
-
-	if (obj->ops->writeback)
-		obj->ops->writeback(obj);
-}
-
 static void __i915_gem_object_reset_page_iter(struct drm_i915_gem_object *obj)
 {
 	struct radix_tree_iter iter;

drivers/gpu/drm/i915/gem/i915_gem_shmem.c

@@ -331,6 +331,23 @@ shmem_writeback(struct drm_i915_gem_object *obj)
 	__shmem_writeback(obj->base.size, obj->base.filp->f_mapping);
 }
 
+static int shmem_shrinker_release_pages(struct drm_i915_gem_object *obj,
+					bool no_gpu_wait,
+					bool writeback)
+{
+	switch (obj->mm.madv) {
+	case I915_MADV_DONTNEED:
+		return i915_gem_object_truncate(obj);
+	case __I915_MADV_PURGED:
+		return 0;
+	}
+
+	if (writeback)
+		shmem_writeback(obj);
+
+	return 0;
+}
+
 void
 __i915_gem_object_release_shmem(struct drm_i915_gem_object *obj,
 				struct sg_table *pages,
@@ -503,7 +520,7 @@ const struct drm_i915_gem_object_ops i915_gem_shmem_ops = {
 	.get_pages = shmem_get_pages,
 	.put_pages = shmem_put_pages,
 	.truncate = shmem_truncate,
-	.writeback = shmem_writeback,
+	.shrinker_release_pages = shmem_shrinker_release_pages,
 
 	.pwrite = shmem_pwrite,
 	.pread = shmem_pread,

drivers/gpu/drm/i915/gem/i915_gem_shrinker.c

@@ -61,18 +61,6 @@ static int try_to_writeback(struct drm_i915_gem_object *obj, unsigned int flags)
 		return obj->ops->shrinker_release_pages(obj,
 							!(flags & I915_SHRINK_ACTIVE),
 							flags & I915_SHRINK_WRITEBACK);
-
-	switch (obj->mm.madv) {
-	case I915_MADV_DONTNEED:
-		i915_gem_object_truncate(obj);
-		return 0;
-	case __I915_MADV_PURGED:
-		return 0;
-	}
-
-	if (flags & I915_SHRINK_WRITEBACK)
-		i915_gem_object_writeback(obj);
-
 	return 0;
 }