new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 8febea6..d7d772b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1635,7 +1635,7 @@
 	 * To do this we must instruct the shmfs to drop all of its
 	 * backing pages, *now*.
 	 */
-	inode = obj->base.filp->f_path.dentry->d_inode;
+	inode = file_inode(obj->base.filp);
 	shmem_truncate_range(inode, 0, (loff_t)-1);
 
 	obj->madv = __I915_MADV_PURGED;
@@ -1800,7 +1800,7 @@
 	 *
 	 * Fail silently without starting the shrinker
 	 */
-	mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
+	mapping = file_inode(obj->base.filp)->i_mapping;
 	gfp = mapping_gfp_mask(mapping);
 	gfp |= __GFP_NORETRY | __GFP_NOWARN | __GFP_NO_KSWAPD;
 	gfp &= ~(__GFP_IO | __GFP_WAIT);
@@ -3724,7 +3724,7 @@
 		mask |= __GFP_DMA32;
 	}
 
-	mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
+	mapping = file_inode(obj->base.filp)->i_mapping;
 	mapping_set_gfp_mask(mapping, mask);
 
 	i915_gem_object_init(obj, &i915_gem_object_ops);
@@ -4228,7 +4228,7 @@
 void i915_gem_detach_phys_object(struct drm_device *dev,
 				 struct drm_i915_gem_object *obj)
 {
-	struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
+	struct address_space *mapping = file_inode(obj->base.filp)->i_mapping;
 	char *vaddr;
 	int i;
 	int page_count;
@@ -4264,7 +4264,7 @@
 			    int id,
 			    int align)
 {
-	struct address_space *mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
+	struct address_space *mapping = file_inode(obj->base.filp)->i_mapping;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	int ret = 0;
 	int page_count;