staging: lustre: llite: don't invoke direct_IO for the EOF case

The function generic_file_read_iter() does not check EOF
before invoke direct_IO callback. So we have to check it
ourselves.
Signed-off-by: Yang Sheng <yang.sheng@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8969
Reviewed-on: https://review.whamcloud.com/24552Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/rw26.c

@@ -345,6 +345,10 @@ static ssize_t ll_direct_IO_26(struct kiocb *iocb, struct iov_iter *iter)
 	ssize_t tot_bytes = 0, result = 0;
 	long size = MAX_DIO_SIZE;
 
+	/* Check EOF by ourselves */
+	if (iov_iter_rw(iter) == READ && file_offset >= i_size_read(inode))
+		return 0;
+
 	/* FIXME: io smaller than PAGE_SIZE is broken on ia64 ??? */
 	if ((file_offset & ~PAGE_MASK) || (count & ~PAGE_MASK))
 		return -EINVAL;