sanitize vfs_fsync calling conventions

Now that the last user passing a NULL file pointer is gone we can remove
the redundant dentry argument and associated hacks inside vfs_fsynmc_range.

The next step will be removig the dentry argument from ->fsync, but given
the luck with the last round of method prototype changes I'd rather
defer this until after the main merge window.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ecryptfs/file.c b/fs/ecryptfs/file.c
index e7440a6..3bdddbc 100644
--- a/fs/ecryptfs/file.c
+++ b/fs/ecryptfs/file.c
@@ -276,9 +276,7 @@
 static int
 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 {
-	return vfs_fsync(ecryptfs_file_to_lower(file),
-			 ecryptfs_dentry_to_lower(dentry),
-			 datasync);
+	return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
 }
 
 static int ecryptfs_fasync(int fd, struct file *file, int flag)