From patchwork Thu Nov 30 17:58:10 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10085503 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 EE0AE60311 for ; Thu, 30 Nov 2017 17:58:22 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF7872A0A8 for ; Thu, 30 Nov 2017 17:58:22 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D33522A21B; Thu, 30 Nov 2017 17:58:22 +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, UNPARSEABLE_RELAY 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 3E5282A0A8 for ; Thu, 30 Nov 2017 17:58:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753837AbdK3R6T (ORCPT ); Thu, 30 Nov 2017 12:58:19 -0500 Received: from aserp1040.oracle.com ([141.146.126.69]:48459 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751178AbdK3R6R (ORCPT ); Thu, 30 Nov 2017 12:58:17 -0500 Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id vAUHwCTb010183 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 30 Nov 2017 17:58:12 GMT Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id vAUHwCJB012002 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 30 Nov 2017 17:58:12 GMT Received: from abhmp0011.oracle.com (abhmp0011.oracle.com [141.146.116.17]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id vAUHwBWt032424; Thu, 30 Nov 2017 17:58:11 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 30 Nov 2017 09:58:11 -0800 Date: Thu, 30 Nov 2017 09:58:10 -0800 From: "Darrick J. Wong" To: alex@zadarastorage.com Cc: linux-xfs@vger.kernel.org, bfoster@redhat.com, david@fromorbit.com, libor.klepac@bcom.cz Subject: [RFC PATCH 2/2] The new attribute leaf buffer is not held locked across the transaction Message-ID: <20171130175810.GJ21412@magnolia> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-Source-IP: aserv0022.oracle.com [141.146.126.234] 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 From: Darrick J. Wong The new attribute leaf buffer is not held locked across the transaction roll between the shortform->leaf modification and the addition of the new entry. As a result, the attribute buffer modification being made is not atomic from an operational perspective. Hence the AIL push can grab it in the transient state of "just created" after the initial transaction is rolled, because the buffer has been released. This leads to xfs_attr3_leaf_verify() asserting that hdr.count is zero, treating this as in-memory corruption, and shutting down the filesystem. Darrick ported the original patch to 4.15 and reworked it use the xfs_defer_bjoin helper and hold/join the buffer correctly across the second transaction roll. Signed-off-by: Alex Lyakas Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_attr.c | 19 +++++++++++++++---- fs/xfs/libxfs/xfs_attr_leaf.c | 9 ++++++--- fs/xfs/libxfs/xfs_attr_leaf.h | 3 ++- 3 files changed, 23 insertions(+), 8 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c index 6249c92..dc7bcf7 100644 --- a/fs/xfs/libxfs/xfs_attr.c +++ b/fs/xfs/libxfs/xfs_attr.c @@ -212,6 +212,7 @@ xfs_attr_set( int flags) { struct xfs_mount *mp = dp->i_mount; + struct xfs_buf *leaf_bp = NULL; struct xfs_da_args args; struct xfs_defer_ops dfops; struct xfs_trans_res tres; @@ -327,9 +328,15 @@ xfs_attr_set( * GROT: another possible req'mt for a double-split btree op. */ xfs_defer_init(args.dfops, args.firstblock); - error = xfs_attr_shortform_to_leaf(&args); + error = xfs_attr_shortform_to_leaf(&args, &leaf_bp); if (error) goto out_defer_cancel; + /* + * Prevent the leaf buffer from being unlocked so that a + * concurrent AIL push cannot grab the half-baked leaf + * buffer and run into problems with the write verifier. + */ + xfs_defer_bjoin(args.dfops, leaf_bp); xfs_defer_ijoin(args.dfops, dp); error = xfs_defer_finish(&args.trans, args.dfops); if (error) @@ -337,13 +344,15 @@ xfs_attr_set( /* * Commit the leaf transformation. We'll need another (linked) - * transaction to add the new attribute to the leaf. + * transaction to add the new attribute to the leaf, which + * means that we have to hold & join the leaf buffer here too. */ - + xfs_trans_bhold(args.trans, leaf_bp); error = xfs_trans_roll_inode(&args.trans, dp); if (error) goto out; - + xfs_trans_bjoin(args.trans, leaf_bp); + leaf_bp = NULL; } if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) @@ -376,6 +385,8 @@ xfs_attr_set( xfs_defer_cancel(&dfops); args.trans = NULL; out: + if (leaf_bp) + xfs_trans_brelse(args.trans, leaf_bp); if (args.trans) xfs_trans_cancel(args.trans); xfs_iunlock(dp, XFS_ILOCK_EXCL); diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c index 8e59375..ebfa477 100644 --- a/fs/xfs/libxfs/xfs_attr_leaf.c +++ b/fs/xfs/libxfs/xfs_attr_leaf.c @@ -739,10 +739,13 @@ xfs_attr_shortform_getvalue(xfs_da_args_t *args) } /* - * Convert from using the shortform to the leaf. + * Convert from using the shortform to the leaf. On success, return the + * buffer so that we can keep it locked until we're totally done with it. */ int -xfs_attr_shortform_to_leaf(xfs_da_args_t *args) +xfs_attr_shortform_to_leaf( + struct xfs_da_args *args, + struct xfs_buf **leaf_bp) { xfs_inode_t *dp; xfs_attr_shortform_t *sf; @@ -822,7 +825,7 @@ xfs_attr_shortform_to_leaf(xfs_da_args_t *args) sfe = XFS_ATTR_SF_NEXTENTRY(sfe); } error = 0; - + *leaf_bp = bp; out: kmem_free(tmpbuffer); return error; diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h index c97f1fe..4da08af 100644 --- a/fs/xfs/libxfs/xfs_attr_leaf.h +++ b/fs/xfs/libxfs/xfs_attr_leaf.h @@ -48,7 +48,8 @@ void xfs_attr_shortform_create(struct xfs_da_args *args); void xfs_attr_shortform_add(struct xfs_da_args *args, int forkoff); int xfs_attr_shortform_lookup(struct xfs_da_args *args); int xfs_attr_shortform_getvalue(struct xfs_da_args *args); -int xfs_attr_shortform_to_leaf(struct xfs_da_args *args); +int xfs_attr_shortform_to_leaf(struct xfs_da_args *args, + struct xfs_buf **leaf_bp); int xfs_attr_shortform_remove(struct xfs_da_args *args); int xfs_attr_shortform_allfit(struct xfs_buf *bp, struct xfs_inode *dp); int xfs_attr_shortform_bytesfit(struct xfs_inode *dp, int bytes);