From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934183AbcIOLzo (ORCPT ); Thu, 15 Sep 2016 07:55:44 -0400 Received: from mga03.intel.com ([134.134.136.65]:23122 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933974AbcIOLzl (ORCPT ); Thu, 15 Sep 2016 07:55:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.30,339,1470726000"; d="scan'208";a="761104966" From: "Kirill A. Shutemov" To: "Theodore Ts'o" , Andreas Dilger , Jan Kara , Andrew Morton Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv3 15/41] filemap: handle huge pages in do_generic_file_read() Date: Thu, 15 Sep 2016 14:54:57 +0300 Message-Id: <20160915115523.29737-16-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20160915115523.29737-1-kirill.shutemov@linux.intel.com> References: <20160915115523.29737-1-kirill.shutemov@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Most of work happans on head page. Only when we need to do copy data to userspace we find relevant subpage. We are still limited by PAGE_SIZE per iteration. Lifting this limitation would require some more work. Signed-off-by: Kirill A. Shutemov --- mm/filemap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index 50afe17230e7..b77bcf6843ee 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1860,6 +1860,7 @@ find_page: if (unlikely(page == NULL)) goto no_cached_page; } + page = compound_head(page); if (PageReadahead(page)) { page_cache_async_readahead(mapping, ra, filp, page, @@ -1936,7 +1937,8 @@ page_ok: * now we can copy it to user space... */ - ret = copy_page_to_iter(page, offset, nr, iter); + ret = copy_page_to_iter(page + index - page->index, offset, + nr, iter); offset += ret; index += offset >> PAGE_SHIFT; offset &= ~PAGE_MASK; @@ -2356,6 +2358,7 @@ page_not_uptodate: * because there really aren't any performance issues here * and we need to check for errors. */ + page = compound_head(page); ClearPageError(page); error = mapping->a_ops->readpage(file, page); if (!error) { -- 2.9.3