From patchwork Tue Aug 7 12:09:37 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 10558641 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C5FA014E5 for ; Tue, 7 Aug 2018 12:09:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B4BC429430 for ; Tue, 7 Aug 2018 12:09:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A701329644; Tue, 7 Aug 2018 12:09:42 +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=-7.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham 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 3A79F29430 for ; Tue, 7 Aug 2018 12:09:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388706AbeHGOXn (ORCPT ); Tue, 7 Aug 2018 10:23:43 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:40218 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727201AbeHGOXn (ORCPT ); Tue, 7 Aug 2018 10:23:43 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Message-Id:Date:Subject:To:From: Sender:Reply-To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: 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=JUSt9Ex51zUCZlh57tnBjR8TC3b6LZAp5L7c+UOQ3GA=; b=QLjz7ZPk6KcifdbKchRDZQzdf OnyC6/Zkw6UQci/QhFYuIe5VtycXZPy5PgnUNa4Er/evidWTqRv49JrDowXMBIEoEj/KyJh3H2BMQ gUpkcs7MZBxA+Zevord+TuS7SjU8E7tHRfIT4UmNae2bKpk69dhjOKFeqluMgWQUolP3EZkOCpvYa HtMu2MiuqLxl8A8MSbdM2H36oJHIV25+tY3h7IFukITCaK4XYDdH6Oshbs8yE5gsJEG6Pnp0LKi9y fmS33Ri9vYsdmcI3S6FdQnNctvy6k5IuiV3nAY+YIPy+dxKPA5Z0YZ13rFqGQhHVPyxvMaNhOHeDK K7MHKtzfg==; Received: from clnet-p19-102.ikbnet.co.at ([83.175.77.102] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fn0nz-0005C7-6p for linux-xfs@vger.kernel.org; Tue, 07 Aug 2018 12:09:39 +0000 From: Christoph Hellwig To: linux-xfs@vger.kernel.org Subject: [PATCH] xfs: use WRITE_ONCE to update if_seq Date: Tue, 7 Aug 2018 14:09:37 +0200 Message-Id: <20180807120937.26597-1-hch@lst.de> X-Mailer: git-send-email 2.18.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This adds ordering of the updates and makes sure we always see the if_seq update before the extent tree is modified. Signed-off-by: Christoph Hellwig Reviewed-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_iext_tree.c | 20 +++++++++++++++++--- fs/xfs/xfs_aops.c | 4 ++-- fs/xfs/xfs_iomap.c | 3 ++- 3 files changed, 21 insertions(+), 6 deletions(-) diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c index 8a7aea041ee1..771dd072015d 100644 --- a/fs/xfs/libxfs/xfs_iext_tree.c +++ b/fs/xfs/libxfs/xfs_iext_tree.c @@ -14,6 +14,7 @@ #include "xfs_inode_fork.h" #include "xfs_trans_resv.h" #include "xfs_mount.h" +#include "xfs_bmap.h" #include "xfs_trace.h" /* @@ -612,6 +613,19 @@ xfs_iext_realloc_root( cur->leaf = new; } +/* + * Increment the sequence counter if we are on a COW fork. This allows + * the writeback code to skip looking for a COW extent if the COW fork + * hasn't changed. We use WRITE_ONCE here to ensure the update to the + * sequence counter is seen before the modifications to the extent + * tree itself take effect. + */ +static inline void xfs_iext_inc_seq(struct xfs_ifork *ifp, int state) +{ + if (state & BMAP_COWFORK) + WRITE_ONCE(ifp->if_seq, READ_ONCE(ifp->if_seq) + 1); +} + void xfs_iext_insert( struct xfs_inode *ip, @@ -624,7 +638,7 @@ xfs_iext_insert( struct xfs_iext_leaf *new = NULL; int nr_entries, i; - ifp->if_seq++; + xfs_iext_inc_seq(ifp, state); if (ifp->if_height == 0) xfs_iext_alloc_root(ifp, cur); @@ -866,7 +880,7 @@ xfs_iext_remove( ASSERT(ifp->if_u1.if_root != NULL); ASSERT(xfs_iext_valid(ifp, cur)); - ifp->if_seq++; + xfs_iext_inc_seq(ifp, state); nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1; for (i = cur->pos; i < nr_entries; i++) @@ -974,7 +988,7 @@ xfs_iext_update_extent( { struct xfs_ifork *ifp = xfs_iext_state_to_fork(ip, state); - ifp->if_seq++; + xfs_iext_inc_seq(ifp, state); if (cur->pos == 0) { struct xfs_bmbt_irec old; diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 235b4ddcd324..49f5f5896a43 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -351,7 +351,7 @@ xfs_map_blocks( if (imap_valid && (!xfs_inode_has_cow_data(ip) || wpc->io_type == XFS_IO_COW || - wpc->cow_seq == ip->i_cowfp->if_seq)) + wpc->cow_seq == READ_ONCE(ip->i_cowfp->if_seq))) return 0; if (XFS_FORCED_SHUTDOWN(mp)) @@ -380,7 +380,7 @@ xfs_map_blocks( xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap)) cow_fsb = imap.br_startoff; if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) { - wpc->cow_seq = ip->i_cowfp->if_seq; + wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq); xfs_iunlock(ip, XFS_ILOCK_SHARED); /* * Truncate can race with writeback since writeback doesn't diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 3282575e2df4..6320aca39f39 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -655,6 +655,7 @@ xfs_iomap_write_allocate( unsigned int *cow_seq) { xfs_mount_t *mp = ip->i_mount; + struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork); xfs_fileoff_t offset_fsb, last_block; xfs_fileoff_t end_fsb, map_start_fsb; xfs_filblks_t count_fsb; @@ -768,7 +769,7 @@ xfs_iomap_write_allocate( goto error0; if (whichfork == XFS_COW_FORK) - *cow_seq = XFS_IFORK_PTR(ip, whichfork)->if_seq; + *cow_seq = READ_ONCE(ifp->if_seq); xfs_iunlock(ip, XFS_ILOCK_EXCL); }