From patchwork Tue Mar 16 20:39:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 12143871 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E102BC433DB for ; Tue, 16 Mar 2021 20:39:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4A8E64F7B for ; Tue, 16 Mar 2021 20:39:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231506AbhCPUj2 (ORCPT ); Tue, 16 Mar 2021 16:39:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:60644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231573AbhCPUjW (ORCPT ); Tue, 16 Mar 2021 16:39:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E241164F80; Tue, 16 Mar 2021 20:39:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1615927162; bh=HIIsnBAdpgzdRnHSnmLypxuABBOe8Oz+vrIslsi72Sg=; h=From:To:Cc:Subject:Date:From; b=WXNL5GVI5sQZ6xiZvd4Kp0znZ4knNMtvneJMnhtUlD7/g9rwmmOrq8GLe2qqtx7WW ZrlmWl3k3S+EKXr38uo3eJvaf4qyCnqYjGX15P7tvEY19cu9xKFKTYG9isNDVgSbZg J9kMVEhG6nyUY+NUNy1ndPyH4p9nfrP4poZ/fehbzLn72RdUrVYPZlEeaibfgtEn+N GMeUceY8QBBFeLIj2fu1MP+AxZh1XkDzfgAh/12FkSVLweBypsb57vgpX7W9wcGq4i lpTp6eV0AXQeGFelckKs7fvKHqXQq62f9MNQ5QuPcCmbHSwt2RiQf4Fq8WASJm3Q7B UCEWKQVOEGDlg== From: Jeff Layton To: ceph-devel@vger.kernel.org, idryomov@gmail.com Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, pdonnell@redhat.com Subject: [PATCH v2] ceph: don't use d_add in ceph_handle_snapdir Date: Tue, 16 Mar 2021 16:39:19 -0400 Message-Id: <20210316203919.102346-1-jlayton@kernel.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org It's possible ceph_get_snapdir could end up finding a (disconnected) inode that already exists in the cache. Change the prototype for ceph_handle_snapdir to return a dentry pointer and have it use d_splice_alias so we don't end up with an aliased dentry in the cache. URL: https://tracker.ceph.com/issues/49843 Reported-by: Al Viro Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li --- fs/ceph/dir.c | 32 ++++++++++++++++++++------------ fs/ceph/file.c | 7 +++++-- fs/ceph/super.h | 2 +- 3 files changed, 26 insertions(+), 15 deletions(-) v2: zero out err var when ceph_handle_snapdir returns success diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index 113f669d71dd..570662dec3fe 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -667,8 +667,8 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence) /* * Handle lookups for the hidden .snap directory. */ -int ceph_handle_snapdir(struct ceph_mds_request *req, - struct dentry *dentry, int err) +struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, + struct dentry *dentry, int err) { struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb); struct inode *parent = d_inode(dentry->d_parent); /* we hold i_mutex */ @@ -676,18 +676,19 @@ int ceph_handle_snapdir(struct ceph_mds_request *req, /* .snap dir? */ if (err == -ENOENT && ceph_snap(parent) == CEPH_NOSNAP && - strcmp(dentry->d_name.name, - fsc->mount_options->snapdir_name) == 0) { + strcmp(dentry->d_name.name, fsc->mount_options->snapdir_name) == 0) { + struct dentry *res; struct inode *inode = ceph_get_snapdir(parent); + if (IS_ERR(inode)) - return PTR_ERR(inode); - dout("ENOENT on snapdir %p '%pd', linking to snapdir %p\n", - dentry, dentry, inode); - BUG_ON(!d_unhashed(dentry)); - d_add(dentry, inode); - err = 0; + return ERR_CAST(inode); + res = d_splice_alias(inode, dentry); + dout("ENOENT on snapdir %p '%pd', linking to snapdir %p. Spliced dentry %p\n", + dentry, dentry, inode, res); + if (res) + dentry = res; } - return err; + return dentry; } /* @@ -743,6 +744,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb); struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(dir->i_sb); struct ceph_mds_request *req; + struct dentry *res; int op; int mask; int err; @@ -793,7 +795,13 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry, req->r_parent = dir; set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags); err = ceph_mdsc_do_request(mdsc, NULL, req); - err = ceph_handle_snapdir(req, dentry, err); + res = ceph_handle_snapdir(req, dentry, err); + if (IS_ERR(res)) { + err = PTR_ERR(res); + } else { + dentry = res; + err = 0; + } dentry = ceph_finish_lookup(req, dentry, err); ceph_mdsc_put_request(req); /* will dput(dentry) */ dout("lookup result=%p\n", dentry); diff --git a/fs/ceph/file.c b/fs/ceph/file.c index 209535d5b8d3..a6ef1d143308 100644 --- a/fs/ceph/file.c +++ b/fs/ceph/file.c @@ -739,9 +739,12 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry, err = ceph_mdsc_do_request(mdsc, (flags & (O_CREAT|O_TRUNC)) ? dir : NULL, req); - err = ceph_handle_snapdir(req, dentry, err); - if (err) + dentry = ceph_handle_snapdir(req, dentry, err); + if (IS_ERR(dentry)) { + err = PTR_ERR(dentry); goto out_req; + } + err = 0; if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry) err = ceph_handle_notrace_create(dir, dentry); diff --git a/fs/ceph/super.h b/fs/ceph/super.h index 188565d806b2..07a3fb52ae30 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -1193,7 +1193,7 @@ extern const struct dentry_operations ceph_dentry_ops; extern loff_t ceph_make_fpos(unsigned high, unsigned off, bool hash_order); extern int ceph_handle_notrace_create(struct inode *dir, struct dentry *dentry); -extern int ceph_handle_snapdir(struct ceph_mds_request *req, +extern struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, struct dentry *dentry, int err); extern struct dentry *ceph_finish_lookup(struct ceph_mds_request *req, struct dentry *dentry, int err);