1 files changed, 46 insertions, 3 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index cf2468da68e9..7de11dcd534d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -381,7 +381,7 @@ static inline struct page *find_subpage(struct page *head, pgoff_t index)
 	if (PageHuge(head))
 		return head;
 
-	return head + (index & (hpage_nr_pages(head) - 1));
+	return head + (index & (thp_nr_pages(head) - 1));
 }
 
 struct page *find_get_entry(struct address_space *mapping, pgoff_t offset);
@@ -496,8 +496,35 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 	return pgoff;
 }
 
+/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */
+struct wait_page_key {
+	struct page *page;
+	int bit_nr;
+	int page_match;
+};
+
+struct wait_page_queue {
+	struct page *page;
+	int bit_nr;
+	wait_queue_entry_t wait;
+};
+
+static inline bool wake_page_match(struct wait_page_queue *wait_page,
+				  struct wait_page_key *key)
+{
+	if (wait_page->page != key->page)
+	       return false;
+	key->page_match = 1;
+
+	if (wait_page->bit_nr != key->bit_nr)
+		return false;
+
+	return true;
+}
+
 extern void __lock_page(struct page *page);
 extern int __lock_page_killable(struct page *page);
+extern int __lock_page_async(struct page *page, struct wait_page_queue *wait);
 extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
 				unsigned int flags);
 extern void unlock_page(struct page *page);
@@ -535,6 +562,22 @@ static inline int lock_page_killable(struct page *page)
 }
 
 /*
+ * lock_page_async - Lock the page, unless this would block. If the page
+ * is already locked, then queue a callback when the page becomes unlocked.
+ * This callback can then retry the operation.
+ *
+ * Returns 0 if the page is locked successfully, or -EIOCBQUEUED if the page
+ * was already locked and the callback defined in 'wait' was queued.
+ */
+static inline int lock_page_async(struct page *page,
+				  struct wait_page_queue *wait)
+{
+	if (!trylock_page(page))
+		return __lock_page_async(page, wait);
+	return 0;
+}
+
+/*
  * lock_page_or_retry - Lock the page, unless this would block and the
  * caller indicated that it can handle a retry.
  *
@@ -730,7 +773,7 @@ static inline struct page *readahead_page(struct readahead_control *rac)
 
 	page = xa_load(&rac->mapping->i_pages, rac->_index);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	rac->_batch_count = hpage_nr_pages(page);
+	rac->_batch_count = thp_nr_pages(page);
 
 	return page;
 }
@@ -753,7 +796,7 @@ static inline unsigned int __readahead_batch(struct readahead_control *rac,
 		VM_BUG_ON_PAGE(!PageLocked(page), page);
 		VM_BUG_ON_PAGE(PageTail(page), page);
 		array[i++] = page;
-		rac->_batch_count += hpage_nr_pages(page);
+		rac->_batch_count += thp_nr_pages(page);
 
 		/*
 		 * The page cache isn't using multi-index entries yet,