1 files changed, 23 insertions, 0 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index f1714758ea96..fcedf5464eb7 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -3035,3 +3035,26 @@ int shmem_zero_setup(struct vm_area_struct *vma)
         vma->vm_flags |= VM_CAN_NONLINEAR;
         return 0;
 }
+
+/**
+ * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
+ * @mapping:    the page's address_space
+ * @index:      the page index
+ * @gfp:        the page allocator flags to use if allocating
+ *
+ * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
+ * with any new page allocations done using the specified allocation flags.
+ * But read_cache_page_gfp() uses the ->readpage() method: which does not
+ * suit tmpfs, since it may have pages in swapcache, and needs to find those
+ * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
+ *
+ * Provide a stub for those callers to start using now, then later
+ * flesh it out to call shmem_getpage() with additional gfp mask, when
+ * shmem_file_splice_read() is added and shmem_readpage() is removed.
+ */
+struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
+                                         pgoff_t index, gfp_t gfp)
+{
+        return read_cache_page_gfp(mapping, index, gfp);
+}
+EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);