[PATCH] NFS: Ensure that dirty pages are written with the right creds.

 When doing shared mmap writes, the resulting dirty NFS pages may
 find themselves incapable of being flushed out if I/O is started
 after the file was released.
 Make sure we start I/O on all existing dirty pages in nfs_file_release().
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfs/file.c

@@ -108,6 +108,9 @@ nfs_file_open(struct inode *inode, struct file *filp)
 static int
 nfs_file_release(struct inode *inode, struct file *filp)
 {
+	/* Ensure that dirty pages are flushed out with the right creds */
+	if (filp->f_mode & FMODE_WRITE)
+		filemap_fdatawrite(filp->f_mapping);
 	return NFS_PROTO(inode)->file_release(inode, filp);
 }