From patchwork Mon Jun 5 16:18:07 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 9766909 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 1E4D76034B for ; Mon, 5 Jun 2017 16:57:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0E1D027E5A for ; Mon, 5 Jun 2017 16:57:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 02BF527F8F; Mon, 5 Jun 2017 16:57:23 +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 8D4D827E5A for ; Mon, 5 Jun 2017 16:57:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753130AbdFEQ1o (ORCPT ); Mon, 5 Jun 2017 12:27:44 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59542 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753031AbdFEQ1m (ORCPT ); Mon, 5 Jun 2017 12:27:42 -0400 Received: from localhost (LFbn-1-12060-104.w90-92.abo.wanadoo.fr [90.92.122.104]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id C31F9B5A; Mon, 5 Jun 2017 16:27:31 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , linux-xfs@vger.kernel.org, "Darrick J . Wong" , Christoph Hellwig Subject: [PATCH 4.9 91/94] xfs: xfs_trans_alloc_empty Date: Mon, 5 Jun 2017 18:18:07 +0200 Message-Id: <20170605153106.907122494@linuxfoundation.org> X-Mailer: git-send-email 2.13.0 In-Reply-To: <20170605153103.156843111@linuxfoundation.org> References: <20170605153103.156843111@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 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 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Hellwig This is a partial cherry-pick of commit e89c041338 ("xfs: implement the GETFSMAP ioctl"), which also adds this helper, and a great example of why feature patches should be properly split into their parts. Signed-off-by: Darrick J. Wong [hch: split from the larger patch for -stable] Signed-off-by: Christoph Hellwig --- fs/xfs/xfs_trans.c | 22 ++++++++++++++++++++++ fs/xfs/xfs_trans.h | 2 ++ 2 files changed, 24 insertions(+) -- 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 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -263,6 +263,28 @@ xfs_trans_alloc( } /* + * Create an empty transaction with no reservation. This is a defensive + * mechanism for routines that query metadata without actually modifying + * them -- if the metadata being queried is somehow cross-linked (think a + * btree block pointer that points higher in the tree), we risk deadlock. + * However, blocks grabbed as part of a transaction can be re-grabbed. + * The verifiers will notice the corrupt block and the operation will fail + * back to userspace without deadlocking. + * + * Note the zero-length reservation; this transaction MUST be cancelled + * without any dirty data. + */ +int +xfs_trans_alloc_empty( + struct xfs_mount *mp, + struct xfs_trans **tpp) +{ + struct xfs_trans_res resv = {0}; + + return xfs_trans_alloc(mp, &resv, 0, 0, XFS_TRANS_NO_WRITECOUNT, tpp); +} + +/* * Record the indicated change to the given field for application * to the file system's superblock when the transaction commits. * For now, just store the change in the transaction structure. --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -159,6 +159,8 @@ typedef struct xfs_trans { int xfs_trans_alloc(struct xfs_mount *mp, struct xfs_trans_res *resp, uint blocks, uint rtextents, uint flags, struct xfs_trans **tpp); +int xfs_trans_alloc_empty(struct xfs_mount *mp, + struct xfs_trans **tpp); void xfs_trans_mod_sb(xfs_trans_t *, uint, int64_t); struct xfs_buf *xfs_trans_get_buf_map(struct xfs_trans *tp,