Pull bugzilla-7570 into release branch

[powerpc.git] / Documentation / filesystems / vfs.txt

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 7737bfd..ea271f2 100644 (file)
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -617,6 +617,11 @@ struct address_space_operations {
        In this case the prepare_write will be retried one the lock is
        regained.
 
+       Note: the page _must not_ be marked uptodate in this function
+       (or anywhere else) unless it actually is uptodate right now. As
+       soon as a page is marked uptodate, it is possible for a concurrent
+       read(2) to copy it to userspace.
+
   commit_write: If prepare_write succeeds, new data will be copied
         into the page and then commit_write will be called.  It will
         typically update the size of the file (if appropriate) and