From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E78E7C2F42E for ; Mon, 21 Jan 2019 15:17:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B260B20879 for ; Mon, 21 Jan 2019 15:17:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="r0vG20fC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729763AbfAUPRG (ORCPT ); Mon, 21 Jan 2019 10:17:06 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:58488 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729678AbfAUPRG (ORCPT ); Mon, 21 Jan 2019 10:17:06 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0QBsGrBnambXVYhRn/4RWqO/IDFh2w6tIZspQZNMz6A=; b=r0vG20fCE7/kXm4yfFohVSquP 5uoo1qBoTJI7OdRr2+sMDeofDqx59DyTelrpm0o5KZMTnqvpMPpIvuwKGSi8acRv8rK2lC02250gi haDhIaOjbw0KT1BIWyFxTVlsHHSlumPm+g2RTV9Q3gecH1A5WSbslJUmT/DrY7THkrAVsTmuXhYkP b5b6WunuFcuppBR8eVcXiovx1a4kYo4B5cO6aYPkGzNh9RVhJanYPU/qKab0ZKcCEXvekAl/+o7SS v6Q6gHjOOpJaiEYAI8t4R2kNRUq8YFYQ/Hgu7T2ZowtVHIV7Wfp+aWKaUVb7IJLRGVj0cXOG9qVuV JNR+jjxAg==; Received: from 089144210168.atnat0019.highway.a1.net ([89.144.210.168] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1glbJx-0006Hv-PI; Mon, 21 Jan 2019 15:17:06 +0000 From: Christoph Hellwig To: linux-xfs@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, Piotr Jaroszynski Subject: [PATCH] iomap: get/put the page in iomap_page_create/release() Date: Mon, 21 Jan 2019 16:17:02 +0100 Message-Id: <20190121151702.28863-1-hch@lst.de> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Piotr Jaroszynski migrate_page_move_mapping() expects pages with private data set to have a page_count elevated by 1. This is what used to happen for xfs through the buffer_heads code before the switch to iomap in commit 82cb14175e7d ("xfs: add support for sub-pagesize writeback without buffer_heads"). Not having the count elevated causes move_pages() to fail on memory mapped files coming from xfs. Make iomap compatible with the migrate_page_move_mapping() assumption by elevating the page count as part of iomap_page_create() and lowering it in iomap_page_release(). It causes the move_pages() syscall to misbehave on memory mapped files from xfs. It does not not move any pages, which I suppose is "just" a perf issue, but it also ends up returning a positive number which is out of spec for the syscall. Talking to Michal Hocko, it sounds like returning positive numbers might be a necessary update to move_pages() anyway though. Fixes: 82cb14175e7d ("xfs: add support for sub-pagesize writeback without buffer_heads") Signed-off-by: Piotr Jaroszynski [hch: actually get/put the page iomap_migrate_page() to make it work properly] Signed-off-by: Christoph Hellwig --- fs/iomap.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/iomap.c b/fs/iomap.c index 987fefc054b4..47362397cb82 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -116,6 +116,12 @@ iomap_page_create(struct inode *inode, struct page *page) atomic_set(&iop->read_count, 0); atomic_set(&iop->write_count, 0); bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE); + + /* + * migrate_page_move_mapping() assumes that pages with private data have + * their count elevated by 1. + */ + get_page(page); set_page_private(page, (unsigned long)iop); SetPagePrivate(page); return iop; @@ -132,6 +138,7 @@ iomap_page_release(struct page *page) WARN_ON_ONCE(atomic_read(&iop->write_count)); ClearPagePrivate(page); set_page_private(page, 0); + put_page(page); kfree(iop); } @@ -569,8 +576,10 @@ iomap_migrate_page(struct address_space *mapping, struct page *newpage, if (page_has_private(page)) { ClearPagePrivate(page); + get_page(newpage); set_page_private(newpage, page_private(page)); set_page_private(page, 0); + put_page(page); SetPagePrivate(newpage); } -- 2.20.1