1 files changed, 33 insertions, 0 deletions
diff --git a/fs/dax.c b/fs/dax.c
index f5fdb43f5de3..f1945aa65eb0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -846,6 +846,39 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
 	return ret;
 }
 
+static int wait_page_idle(struct page *page,
+			void (cb)(struct inode *),
+			struct inode *inode)
+{
+	return ___wait_var_event(page, dax_page_is_idle(page),
+				TASK_INTERRUPTIBLE, 0, 0, cb(inode));
+}
+
+/*
+ * Unmaps the inode and waits for any DMA to complete prior to deleting the
+ * DAX mapping entries for the range.
+ */
+int dax_break_layout(struct inode *inode, loff_t start, loff_t end,
+		void (cb)(struct inode *))
+{
+	struct page *page;
+	int error = 0;
+
+	if (!dax_mapping(inode->i_mapping))
+		return 0;
+
+	do {
+		page = dax_layout_busy_page_range(inode->i_mapping, start, end);
+		if (!page)
+			break;
+
+		error = wait_page_idle(page, cb, inode);
+	} while (error == 0);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(dax_break_layout);
+
 /*
  * Invalidate DAX entry if it is clean.
  */