From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755506AbcGZAgL (ORCPT ); Mon, 25 Jul 2016 20:36:11 -0400 Received: from mga02.intel.com ([134.134.136.20]:14905 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755290AbcGZAgA (ORCPT ); Mon, 25 Jul 2016 20:36:00 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,421,1464678000"; d="scan'208";a="1013759502" From: "Kirill A. Shutemov" To: "Theodore Ts'o" , Andreas Dilger , Jan Kara Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Andrew Morton , 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: [PATCHv1, RFC 14/33] filemap: handle huge pages in do_generic_file_read() Date: Tue, 26 Jul 2016 03:35:16 +0300 Message-Id: <1469493335-3622-15-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1469493335-3622-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1469493335-3622-1-git-send-email-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 a3183e688718..566c7e6ca423 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1819,6 +1819,7 @@ 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, @@ -1895,7 +1896,8 @@ 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; @@ -2315,6 +2317,7 @@ 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) { -- 2.8.1