From patchwork Sat Mar 31 04:03:46 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 10318605 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 494DC60467 for ; Sat, 31 Mar 2018 04:13:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 397DD2A258 for ; Sat, 31 Mar 2018 04:13:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2E6192A395; Sat, 31 Mar 2018 04:13:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9BEE12A258 for ; Sat, 31 Mar 2018 04:13:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753113AbeCaENn (ORCPT ); Sat, 31 Mar 2018 00:13:43 -0400 Received: from mga03.intel.com ([134.134.136.65]:25317 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753103AbeCaENl (ORCPT ); Sat, 31 Mar 2018 00:13:41 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Mar 2018 21:13:41 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,383,1517904000"; d="scan'208";a="29893073" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.16]) by orsmga008.jf.intel.com with ESMTP; 30 Mar 2018 21:13:41 -0700 Subject: [PATCH v8 18/18] xfs, dax: introduce xfs_break_dax_layouts() From: Dan Williams To: linux-nvdimm@lists.01.org Cc: Jan Kara , Dave Chinner , "Darrick J. Wong" , Ross Zwisler , Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, jack@suse.cz, snitzer@redhat.com Date: Fri, 30 Mar 2018 21:03:46 -0700 Message-ID: <152246902607.36038.15813002361509305325.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <152246892890.36038.18436540150980653229.stgit@dwillia2-desk3.amr.corp.intel.com> References: <152246892890.36038.18436540150980653229.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-2-gc94f MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP xfs_break_dax_layouts(), similar to xfs_break_leased_layouts(), scans for busy / pinned dax pages and waits for those pages to go idle before any potential extent unmap operation. dax_layout_busy_page() handles synchronizing against new page-busy events (get_user_pages). It invalidates all mappings to trigger the get_user_pages slow path which will eventually block on the xfs inode lock held in XFS_MMAPLOCK_EXCL mode. If dax_layout_busy_page() finds a busy page it returns it for xfs to wait for the page-idle event that will fire when the page reference count reaches 1 (recall ZONE_DEVICE pages are idle at count 1, see generic_dax_pagefree()). While waiting, the XFS_MMAPLOCK_EXCL lock is dropped in order to not deadlock the process that might be trying to elevate the page count of more pages before arranging for any of them to go idle. I.e. the typical case of submitting I/O is that iov_iter_get_pages() elevates the reference count of all pages in the I/O before starting I/O on the first page. The process of elevating the reference count of all pages involved in an I/O may cause faults that need to take XFS_MMAPLOCK_EXCL. Cc: Jan Kara Cc: Dave Chinner Cc: "Darrick J. Wong" Cc: Ross Zwisler Reviewed-by: Christoph Hellwig Signed-off-by: Dan Williams --- fs/xfs/xfs_file.c | 60 +++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 49 insertions(+), 11 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 51e6506bdcb1..0342f6fb782f 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -752,6 +752,38 @@ xfs_file_write_iter( return ret; } +static void +xfs_wait_var_event( + struct inode *inode, + uint iolock, + bool *did_unlock) +{ + struct xfs_inode *ip = XFS_I(inode); + + *did_unlock = true; + xfs_iunlock(ip, iolock); + schedule(); + xfs_ilock(ip, iolock); +} + +static int +xfs_break_dax_layouts( + struct inode *inode, + uint iolock, + bool *did_unlock) +{ + struct page *page; + + *did_unlock = false; + page = dax_layout_busy_page(inode->i_mapping); + if (!page) + return 0; + + return ___wait_var_event(&page->_refcount, + atomic_read(&page->_refcount) == 1, TASK_INTERRUPTIBLE, + 0, 0, xfs_wait_var_event(inode, iolock, did_unlock)); +} + int xfs_break_layouts( struct inode *inode, @@ -763,17 +795,23 @@ xfs_break_layouts( ASSERT(xfs_isilocked(XFS_I(inode), XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL)); - switch (reason) { - case BREAK_UNMAP: - ASSERT(xfs_isilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL)); - /* fall through */ - case BREAK_WRITE: - error = xfs_break_leased_layouts(inode, iolock, &retry); - break; - default: - WARN_ON_ONCE(1); - return -EINVAL; - } + do { + switch (reason) { + case BREAK_UNMAP: + ASSERT(xfs_isilocked(XFS_I(inode), XFS_MMAPLOCK_EXCL)); + + error = xfs_break_dax_layouts(inode, *iolock, &retry); + /* fall through */ + case BREAK_WRITE: + if (error || retry) + break; + error = xfs_break_leased_layouts(inode, iolock, &retry); + break; + default: + WARN_ON_ONCE(1); + return -EINVAL; + } + } while (error == 0 && retry); return error; }