From patchwork Sun Jul 29 22:04:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 10548327 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 274551751 for ; Sun, 29 Jul 2018 22:05:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 19612288DD for ; Sun, 29 Jul 2018 22:05:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0DCAC28C68; Sun, 29 Jul 2018 22:05:15 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI 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 94BFA288DD for ; Sun, 29 Jul 2018 22:05:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731339AbeG2XhI (ORCPT ); Sun, 29 Jul 2018 19:37:08 -0400 Received: from zeniv.linux.org.uk ([195.92.253.2]:51606 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729011AbeG2Xg5 (ORCPT ); Sun, 29 Jul 2018 19:36:57 -0400 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.87 #1 (Red Hat Linux)) id 1fjto6-0003W4-R4; Sun, 29 Jul 2018 22:04:54 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , linux-kernel@vger.kernel.org, Miklos Szeredi , Miklos Szeredi Subject: [PATCH 10/16] kill d_instantiate_no_diralias() Date: Sun, 29 Jul 2018 23:04:47 +0100 Message-Id: <20180729220453.13431-10-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20180729220453.13431-1-viro@ZenIV.linux.org.uk> References: <20180729220317.GB30522@ZenIV.linux.org.uk> <20180729220453.13431-1-viro@ZenIV.linux.org.uk> 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: Al Viro The only user is fuse_create_new_entry(), and there it's used to mitigate the same mkdir/open-by-handle race as in nfs_mkdir(). The same solution applies - unhash the mkdir argument, then call d_splice_alias() and if that returns a reference to preexisting alias, dput() and report success. ->mkdir() argument left unhashed negative with the preexisting alias moved in the right place is just fine from the ->mkdir() callers point of view. Cc: Miklos Szeredi Signed-off-by: Al Viro --- fs/dcache.c | 27 --------------------------- fs/fuse/dir.c | 15 +++++++++++---- include/linux/dcache.h | 1 - 3 files changed, 11 insertions(+), 32 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index 0e8e5de3c48a..a7d9e7a4c283 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1899,33 +1899,6 @@ void d_instantiate_new(struct dentry *entry, struct inode *inode) } EXPORT_SYMBOL(d_instantiate_new); -/** - * d_instantiate_no_diralias - instantiate a non-aliased dentry - * @entry: dentry to complete - * @inode: inode to attach to this dentry - * - * Fill in inode information in the entry. If a directory alias is found, then - * return an error (and drop inode). Together with d_materialise_unique() this - * guarantees that a directory inode may never have more than one alias. - */ -int d_instantiate_no_diralias(struct dentry *entry, struct inode *inode) -{ - BUG_ON(!hlist_unhashed(&entry->d_u.d_alias)); - - security_d_instantiate(entry, inode); - spin_lock(&inode->i_lock); - if (S_ISDIR(inode->i_mode) && !hlist_empty(&inode->i_dentry)) { - spin_unlock(&inode->i_lock); - iput(inode); - return -EBUSY; - } - __d_instantiate(entry, inode); - spin_unlock(&inode->i_lock); - - return 0; -} -EXPORT_SYMBOL(d_instantiate_no_diralias); - struct dentry *d_make_root(struct inode *root_inode) { struct dentry *res = NULL; diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index 56231b31f806..4bbae6ac75c3 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -539,6 +539,7 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args, { struct fuse_entry_out outarg; struct inode *inode; + struct dentry *d; int err; struct fuse_forget_link *forget; @@ -570,11 +571,17 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_args *args, } kfree(forget); - err = d_instantiate_no_diralias(entry, inode); - if (err) - return err; + d_drop(entry); + d = d_splice_alias(inode, entry); + if (IS_ERR(d)) + return PTR_ERR(d); - fuse_change_entry_timeout(entry, &outarg); + if (d) { + fuse_change_entry_timeout(d, &outarg); + dput(d); + } else { + fuse_change_entry_timeout(entry, &outarg); + } fuse_invalidate_attr(dir); return 0; diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 66c6e17e61e5..0b83629a3d8f 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -227,7 +227,6 @@ extern void d_instantiate(struct dentry *, struct inode *); extern void d_instantiate_new(struct dentry *, struct inode *); extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *); extern struct dentry * d_instantiate_anon(struct dentry *, struct inode *); -extern int d_instantiate_no_diralias(struct dentry *, struct inode *); extern void __d_drop(struct dentry *dentry); extern void d_drop(struct dentry *dentry); extern void d_delete(struct dentry *);