drm/i915: use shmem_truncate_range

The interface to ->truncate_range is changing very slightly: once "tmpfs:
take control of its truncate_range" has been applied, this can be applied.
 For now there is only a slight inefficiency while this remains unapplied,
but it will soon become essential for managing shmem's use of swap.

Change i915_gem_object_truncate() to use shmem_truncate_range() directly:
which should also spare i915 later change if we switch from
inode_operations->truncate_range to file_operations->fallocate.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Keith Packard <keithp@keithp.com>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index fa560ceba667..85f713746a1f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1696,13 +1696,10 @@ i915_gem_object_truncate(struct drm_i915_gem_object *obj)
         /* Our goal here is to return as much of the memory as
          * is possible back to the system as we are called from OOM.
          * To do this we must instruct the shmfs to drop all of its
-         * backing pages, *now*. Here we mirror the actions taken
-         * when by shmem_delete_inode() to release the backing store.
+         * backing pages, *now*.
          */
         inode = obj->base.filp->f_path.dentry->d_inode;
-        truncate_inode_pages(inode->i_mapping, 0);
-        if (inode->i_op->truncate_range)
-                inode->i_op->truncate_range(inode, 0, (loff_t)-1);
+        shmem_truncate_range(inode, 0, (loff_t)-1);
 
         obj->madv = __I915_MADV_PURGED;
 }