+ } else {
+ folio_unlock(to_folio);
+ }
+
+ folio_put(to_folio);
+
+ return handle;
+}
+
+/**
+ * ttm_backup_fini() - Free the struct backup resources after last
use.
+ * @backup: Pointer to the struct backup whose resources to free.
+ *
+ * After a call to this function, it's illegal to use the @backup
pointer.
+ */
+void ttm_backup_fini(struct ttm_backup *backup)
+{
+ fput(ttm_backup_to_file(backup));
+}
+
+/**
+ * ttm_backup_bytes_avail() - Report the approximate number of
bytes of backup space
+ * left for backup.
+ *
+ * This function is intended also for driver use to indicate
whether a
+ * backup attempt is meaningful.
+ *
+ * Return: An approximate size of backup space available.
+ */
+u64 ttm_backup_bytes_avail(void)
+{
+ /*
+ * The idea behind backing up to shmem is that shmem
objects may
+ * eventually be swapped out. So no point swapping out if
there
+ * is no or low swap-space available. But the accuracy of
this
+ * number also depends on shmem actually swapping out
backed-up
+ * shmem objects without too much buffering.
+ */
+ return (u64)get_nr_swap_pages() << PAGE_SHIFT;
+}
+EXPORT_SYMBOL_GPL(ttm_backup_bytes_avail);
+
+/**
+ * ttm_backup_shmem_create() - Create a shmem-based struct backup.
+ * @size: The maximum size (in bytes) to back up.
+ *
+ * Create a backup utilizing shmem objects.
+ *
+ * Return: A pointer to a struct ttm_backup on success,
+ * an error pointer on error.
+ */
+struct ttm_backup *ttm_backup_shmem_create(loff_t size)
+{
+ struct file *filp;
+
+ filp = shmem_file_setup("ttm shmem backup", size, 0);
+
+ return ttm_file_to_backup(filp);
+}
diff --git a/include/drm/ttm/ttm_backup.h
b/include/drm/ttm/ttm_backup.h
new file mode 100644
index 000000000000..20609da7e281
--- /dev/null
+++ b/include/drm/ttm/ttm_backup.h
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2024 Intel Corporation
+ */
+
+#ifndef _TTM_BACKUP_H_
+#define _TTM_BACKUP_H_
+
+#include <linux/mm_types.h>
+#include <linux/shmem_fs.h>
+
+struct ttm_backup;
+
+/**
+ * ttm_backup_handle_to_page_ptr() - Convert handle to struct page
pointer
+ * @handle: The handle to convert.
+ *
+ * Converts an opaque handle received from the
+ * struct ttm_backoup_ops::backup_page() function to an (invalid)
+ * struct page pointer suitable for a struct page array.
+ *
+ * Return: An (invalid) struct page pointer.
+ */
+static inline struct page *
+ttm_backup_handle_to_page_ptr(unsigned long handle)
+{
+ return (struct page *)(handle << 1 | 1);
+}
+
+/**
+ * ttm_backup_page_ptr_is_handle() - Whether a struct page pointer
is a handle
+ * @page: The struct page pointer to check.
+ *
+ * Return: true if the struct page pointer is a handld returned
from
+ * ttm_backup_handle_to_page_ptr(). False otherwise.
+ */
+static inline bool ttm_backup_page_ptr_is_handle(const struct page
*page)
+{
+ return (unsigned long)page & 1;
+}
+
+/**
+ * ttm_backup_page_ptr_to_handle() - Convert a struct page pointer
to a handle
+ * @page: The struct page pointer to convert
+ *
+ * Return: The handle that was previously used in
+ * ttm_backup_handle_to_page_ptr() to obtain a struct page
pointer, suitable
+ * for use as argument in the struct ttm_backup_ops drop() or
+ * copy_backed_up_page() functions.
+ */
+static inline unsigned long
+ttm_backup_page_ptr_to_handle(const struct page *page)
+{
+ WARN_ON(!ttm_backup_page_ptr_is_handle(page));
+ return (unsigned long)page >> 1;
+}
+
+void ttm_backup_drop(struct ttm_backup *backup, pgoff_t handle);
+
+int ttm_backup_copy_page(struct ttm_backup *backup, struct page
*dst,
+ pgoff_t handle, bool intr);
+
+unsigned long
+ttm_backup_backup_page(struct ttm_backup *backup, struct page
*page,
+ bool writeback, pgoff_t idx, gfp_t
page_gfp,
+ gfp_t alloc_gfp);
+
+void ttm_backup_fini(struct ttm_backup *backup);
+
+u64 ttm_backup_bytes_avail(void);
+
+struct ttm_backup *ttm_backup_shmem_create(loff_t size);
+
+#endif