From patchwork Thu Feb 14 23:49:08 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 10814027 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 A34C013BF for ; Thu, 14 Feb 2019 23:50:09 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8F45C2E779 for ; Thu, 14 Feb 2019 23:50:09 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 824942E763; Thu, 14 Feb 2019 23:50:09 +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=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, UNPARSEABLE_RELAY 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 00A6E2E779 for ; Thu, 14 Feb 2019 23:50:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729448AbfBNXuG (ORCPT ); Thu, 14 Feb 2019 18:50:06 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:36118 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726178AbfBNXuG (ORCPT ); Thu, 14 Feb 2019 18:50:06 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x1ENn4Y9057714; Thu, 14 Feb 2019 23:49:15 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : mime-version : content-type; s=corp-2018-07-02; bh=4zja+sZjQPQ9x+0uQqxzzTRDfja/Krlmvk/CVa3qdOQ=; b=Al+VIW0aOmLYcb8AiAaYdIODJ+7H86i4reDBAj6Kt/4tSrJBkU4C6TYO9C8uLXu4+25J jI3QQ20mmbVqKjbIa6w9s6yOBxoLsfUnSGTS+e8EJpXFDDCnx4j14dzb/jZ6dR54yg2j QIeNg79TQcbaxHg4ts/nXcZyrxvRDFq+7LJsR320+MgPuqWuz6vxddeXLb7jQIrXKcKV oPM2US56vRsXcx9efZlpeGouUPvWyzUBZsRXNGetHEdFnYmoGGe0vTCfL2FrXV0IM36K POa81aT9rPE4E3dYc5UPwblwaUETYsgw5vIZdSpR86SPc/FcwjFTX/PEOXZmUUwDxG8y pw== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2120.oracle.com with ESMTP id 2qhreeb0h3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 14 Feb 2019 23:49:15 +0000 Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x1ENnFfG022416 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 14 Feb 2019 23:49:15 GMT Received: from abhmp0001.oracle.com (abhmp0001.oracle.com [141.146.116.7]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x1ENnBiV001587; Thu, 14 Feb 2019 23:49:11 GMT Received: from localhost (/10.159.142.29) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 14 Feb 2019 15:49:11 -0800 Date: Thu, 14 Feb 2019 15:49:08 -0800 From: "Darrick J. Wong" To: clm@fb.com, josef@toxicpanda.com, dsterba@suse.com, viro@zeniv.linux.org.uk, jack@suse.com, tytso@mit.edu, adilger.kernel@dilger.ca, jaegeuk@kernel.org, yuchao0@huawei.com, hughd@google.com, darrick.wong@oracle.com, hch@infradead.org Cc: richard@nod.at, dedekind1@gmail.com, adrian.hunter@intel.com, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, linux-mm@kvack.org Subject: [PATCH] vfs: don't decrement i_nlink in d_tmpfile Message-ID: <20190214234908.GA6474@magnolia> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9167 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=866 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902140156 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 From: Darrick J. Wong d_tmpfile was introduced to instantiate an inode in the dentry cache as a temporary file. This helper decrements the inode's nlink count and dirties the inode, presumably so that filesystems could call new_inode to create a new inode with nlink == 1 and then call d_tmpfile which will decrement nlink. However, this doesn't play well with XFS, which needs to allocate, initialize, and insert a tempfile inode on its unlinked list in a single transaction. In order to maintain referential integrity of the XFS metadata, we cannot have an inode on the unlinked list with nlink >= 1. XFS and btrfs hack around d_tmpfile's behavior by creating the inode with nlink == 0 and then incrementing it just prior to calling d_tmpfile, anticipating that it will be reset to 0. Everywhere else outside of d_tmpfile, it appears that nlink updates and persistence is the responsibility of individual filesystems. Therefore, move the nlink decrement out of d_tmpfile into the callers, and require that callers only pass in inodes with nlink already set to 0. Signed-off-by: Darrick J. Wong --- fs/btrfs/inode.c | 8 -------- fs/dcache.c | 8 ++++++-- fs/ext2/namei.c | 2 +- fs/ext4/namei.c | 1 + fs/f2fs/namei.c | 1 + fs/minix/namei.c | 2 +- fs/ubifs/dir.c | 1 + fs/udf/namei.c | 2 +- fs/xfs/xfs_iops.c | 13 ++----------- mm/shmem.c | 1 + 10 files changed, 15 insertions(+), 24 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 5c349667c761..bd189fc50f83 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -10382,14 +10382,6 @@ static int btrfs_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) if (ret) goto out; - /* - * We set number of links to 0 in btrfs_new_inode(), and here we set - * it to 1 because d_tmpfile() will issue a warning if the count is 0, - * through: - * - * d_tmpfile() -> inode_dec_link_count() -> drop_nlink() - */ - set_nlink(inode, 1); d_tmpfile(dentry, inode); unlock_new_inode(inode); mark_inode_dirty(inode); diff --git a/fs/dcache.c b/fs/dcache.c index aac41adf4743..5fb4ecce2589 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -3042,12 +3042,16 @@ void d_genocide(struct dentry *parent) EXPORT_SYMBOL(d_genocide); +/* + * Instantiate an inode in the dentry cache as a temporary file. Callers must + * ensure that @inode has a zero link count. + */ void d_tmpfile(struct dentry *dentry, struct inode *inode) { - inode_dec_link_count(inode); BUG_ON(dentry->d_name.name != dentry->d_iname || !hlist_unhashed(&dentry->d_u.d_alias) || - !d_unlinked(dentry)); + !d_unlinked(dentry) || + inode->i_nlink != 0); spin_lock(&dentry->d_parent->d_lock); spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); dentry->d_name.len = sprintf(dentry->d_iname, "#%llu", diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c index 0c26dcc5d850..8542e9ce9677 100644 --- a/fs/ext2/namei.c +++ b/fs/ext2/namei.c @@ -117,7 +117,7 @@ static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) return PTR_ERR(inode); ext2_set_file_ops(inode); - mark_inode_dirty(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); unlock_new_inode(inode); return 0; diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index 2b928eb07fa2..7502432f9816 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2517,6 +2517,7 @@ static int ext4_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) inode->i_op = &ext4_file_inode_operations; inode->i_fop = &ext4_file_operations; ext4_set_aops(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); err = ext4_orphan_add(handle, inode); if (err) diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c index 62d9829f3a6a..31a556af5f3a 100644 --- a/fs/f2fs/namei.c +++ b/fs/f2fs/namei.c @@ -780,6 +780,7 @@ static int __f2fs_tmpfile(struct inode *dir, struct dentry *dentry, f2fs_i_links_write(inode, false); *whiteout = inode; } else { + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } /* link_count was changed by d_tmpfile as well. */ diff --git a/fs/minix/namei.c b/fs/minix/namei.c index 1a6084d2b02e..3249f86c476a 100644 --- a/fs/minix/namei.c +++ b/fs/minix/namei.c @@ -57,7 +57,7 @@ static int minix_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) struct inode *inode = minix_new_inode(dir, mode, &error); if (inode) { minix_set_inode(inode, 0); - mark_inode_dirty(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } return error; diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c index 5767b373a8ff..7187e4fd7561 100644 --- a/fs/ubifs/dir.c +++ b/fs/ubifs/dir.c @@ -419,6 +419,7 @@ static int do_tmpfile(struct inode *dir, struct dentry *dentry, drop_nlink(inode); *whiteout = inode; } else { + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } ubifs_assert(c, ui->dirty); diff --git a/fs/udf/namei.c b/fs/udf/namei.c index 58cc2414992b..38bd021f9673 100644 --- a/fs/udf/namei.c +++ b/fs/udf/namei.c @@ -652,7 +652,7 @@ static int udf_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) inode->i_data.a_ops = &udf_aops; inode->i_op = &udf_file_inode_operations; inode->i_fop = &udf_file_operations; - mark_inode_dirty(inode); + inode_dec_link_count(inode); d_tmpfile(dentry, inode); unlock_new_inode(inode); return 0; diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c index 1efef69a7f1c..f48ffd7a8d3e 100644 --- a/fs/xfs/xfs_iops.c +++ b/fs/xfs/xfs_iops.c @@ -191,18 +191,9 @@ xfs_generic_create( xfs_setup_iops(ip); - if (tmpfile) { - /* - * The VFS requires that any inode fed to d_tmpfile must have - * nlink == 1 so that it can decrement the nlink in d_tmpfile. - * However, we created the temp file with nlink == 0 because - * we're not allowed to put an inode with nlink > 0 on the - * unlinked list. Therefore we have to set nlink to 1 so that - * d_tmpfile can immediately set it back to zero. - */ - set_nlink(inode, 1); + if (tmpfile) d_tmpfile(dentry, inode); - } else + else d_instantiate(dentry, inode); xfs_finish_inode_setup(ip); diff --git a/mm/shmem.c b/mm/shmem.c index 6ece1e2fe76e..4a7810093561 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2818,6 +2818,7 @@ shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) error = simple_acl_create(dir, inode); if (error) goto out_iput; + inode_dec_link_count(inode); d_tmpfile(dentry, inode); } return error;