From patchwork Thu May 3 17:53:43 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10378807 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 1D4E660327 for ; Thu, 3 May 2018 17:54:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 094EA29210 for ; Thu, 3 May 2018 17:54:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F1FC729213; Thu, 3 May 2018 17:54:14 +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, 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 704E529210 for ; Thu, 3 May 2018 17:54:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751279AbeECRyM (ORCPT ); Thu, 3 May 2018 13:54:12 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:51612 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751075AbeECRyI (ORCPT ); Thu, 3 May 2018 13:54:08 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w43Hjkhq182225; Thu, 3 May 2018 17:53:49 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2017-10-26; bh=m/h17V54YyGlwMGrMMmPO30pVuLBRqnhlc6KsyyXPkY=; b=tnJYUOH0ECwlD2jIwFN4M5L/N7ZP48xj3AdJjaE4uEpnLYeZN5MGdF3Xa6M2kuzHIu4y DndxgGSYbc04WFKdAeATDR9EZqmLyZxlG1B4N/8iCr+Gnbp2gMYm6UuJ44yIhSgJnMwO /NpNNGpQR2PI8KKybAQd/1ncIVZRFPJZ3lVCRkN1eLywEwKtgD6MuwgAeO8UF1b2BcO9 FubhL32VTUgzEIWnxFecBgc09i6pQ+VKoAhibsbdnxaBCICdiB6sB1KDX6+VD9ZmqVPR bDlS6pE72yIhc4XrMgggfhl0XbFw0Oyv75VeUfsmSakHbMnc3htga/pEwsMpOC7MFom1 lg== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2130.oracle.com with ESMTP id 2hmgdjtyht-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 03 May 2018 17:53:48 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w43HrmUh019787 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 3 May 2018 17:53:48 GMT Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w43Hrieo028384; Thu, 3 May 2018 17:53:48 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 03 May 2018 10:53:44 -0700 Date: Thu, 3 May 2018 10:53:43 -0700 From: "Darrick J. Wong" To: linux-xfs@vger.kernel.org, bfoster@redhat.com, hch@lst.de Subject: [PATCH 0.1/13] xfs: release new dquot buffer on defer_finish error Message-ID: <20180503175343.GF4127@magnolia> References: <152506698177.21553.13500862866416804148.stgit@magnolia> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <152506698177.21553.13500862866416804148.stgit@magnolia> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8882 signatures=668698 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1805030153 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 In commit efa092f3d4c6 "[XFS] Fixes a bug in the quota code when allocating a new dquot record", we allocate a new dquot block, grab a buffer to initialize it, and return the locked initialized dquot buffer to the caller for further in-core dquot initialization. Unfortunately, if the _bmap_finish errored out, _qm_dqalloc would also error out without bothering to free the (locked) buffer. Leaking a locked buffer caused hangs in generic/388 when quotas are enabled. Furthermore, the _bmap_finish -> _defer_finish conversion in 310a75a3c6c747 ("xfs: change xfs_bmap_{finish,cancel,init,free} -> xfs_defer_*") failed to observe that the buffer was held going into _defer_finish and therefore failed to notice that the buffer lock is /not/ maintained afterwards. Now that we can bjoin a buffer to a defer_ops, use this mechanism to ensure that the buffer stays locked across the _defer_finish. Release the holds and locks on the buffer as appropriate if we have to error out. There is a subtlety here for the caller in that the buffer emerges locked and held to the transaction, so if the _trans_commit fails we have to release the buffer explicitly. This fixes the unmount hang in generic/388 when quotas are enabled. Signed-off-by: Darrick J. Wong --- fs/xfs/xfs_dquot.c | 48 +++++++++++++++++++++++++++--------------------- 1 file changed, 27 insertions(+), 21 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/xfs_dquot.c b/fs/xfs/xfs_dquot.c index a7daef9e16bf..4c39d8632230 100644 --- a/fs/xfs/xfs_dquot.c +++ b/fs/xfs/xfs_dquot.c @@ -362,33 +362,39 @@ xfs_qm_dqalloc( dqp->dq_flags & XFS_DQ_ALLTYPES, bp); /* - * xfs_defer_finish() may commit the current transaction and - * start a second transaction if the freelist is not empty. + * Hold the buffer and join it to the dfops so that we'll still own + * the buffer when we return to the caller. The buffer disposal on + * error must be paid attention to very carefully, as it has been + * broken since commit efa092f3d4c6 "[XFS] Fixes a bug in the quota + * code when allocating a new dquot record" in 2005, and the later + * conversion to xfs_defer_ops in commit 310a75a3c6c747 failed to keep + * the buffer locked across the _defer_finish call. We can now do + * this correctly with xfs_defer_bjoin. * - * Since we still want to modify this buffer, we need to - * ensure that the buffer is not released on commit of - * the first transaction and ensure the buffer is added to the - * second transaction. + * Above, we allocated a disk block for the dquot information and + * used get_buf to initialize the dquot. If the _defer_bjoin fails, + * the buffer is still locked to *tpp, so we must _bhold_release and + * then _trans_brelse the buffer. If the _defer_finish fails, the old + * transaction is gone but the new buffer is not joined or held to any + * transaction, so we must _buf_relse it. * - * If there is only one transaction then don't stop the buffer - * from being released when it commits later on. + * If everything succeeds, the caller of this function is returned a + * buffer that is locked, held, and joined to the transaction. If the + * transaction commit fails (in the caller) the caller must unlock the + * buffer manually. */ - - xfs_trans_bhold(tp, bp); - + xfs_trans_bhold(*tpp, bp); + error = xfs_defer_bjoin(&dfops, bp); + if (error) { + xfs_trans_bhold_release(*tpp, bp); + xfs_trans_brelse(*tpp, bp); + goto error1; + } error = xfs_defer_finish(tpp, &dfops); - if (error) + if (error) { + xfs_buf_relse(bp); goto error1; - - /* Transaction was committed? */ - if (*tpp != tp) { - tp = *tpp; - xfs_trans_bjoin(tp, bp); - } else { - xfs_trans_bhold_release(tp, bp); } - - *O_bpp = bp; return 0; error1: