1 files changed, 12 insertions, 0 deletions

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index aa754e01464e..065aa2dc0835 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -592,6 +592,8 @@ struct address_space_operations {
         int (*migratepage) (struct page *, struct page *);
         int (*launder_page) (struct page *);
         int (*error_remove_page) (struct mapping *mapping, struct page *page);
+        int (*swap_activate)(struct file *);
+        int (*swap_deactivate)(struct file *);
 };
 
   writepage: called by the VM to write a dirty page to backing store.
@@ -760,6 +762,16 @@ struct address_space_operations {
         Setting this implies you deal with pages going away under you,
         unless you have them locked or reference counts increased.
 
+  swap_activate: Called when swapon is used on a file to allocate
+        space if necessary and pin the block lookup information in
+        memory. A return value of zero indicates success,
+        in which case this file can be used to back swapspace. The
+        swapspace operations will be proxied to this address space's
+        ->swap_{out,in} methods.
+
+  swap_deactivate: Called during swapoff on files where swap_activate
+        was successful.
+
 
 The File Object
 ===============