From mboxrd@z Thu Jan 1 00:00:00 1970 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=-16.2 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 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 E6EE6C2B9F4 for ; Tue, 22 Jun 2021 12:24:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D0C6D6023B for ; Tue, 22 Jun 2021 12:24:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231408AbhFVM0Z (ORCPT ); Tue, 22 Jun 2021 08:26:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:42676 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231404AbhFVM0Y (ORCPT ); Tue, 22 Jun 2021 08:26:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E237961353; Tue, 22 Jun 2021 12:24:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624364649; bh=oneXQObMwAf4wFpfwDsj76N7x/37zxoY2XuNStd0kVs=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=nsd4TLeNTGGFYGsYWgQINse+M+MEnx1Bc3RkJUSTCmA1GfxZouPIV1CnkeFUFM1Cg h6Y99IiCDWvrvTXwyDqihEqx7Id94IZIF1Xz4RYwUayl/uZlO70KTd7y22YowDf8wF HfqG7K7S7Z1SW9GmSeXHv32Rx7EJBbclVQzdlbhEnduCE4RLsrAGzUvujTnzGqTs/i f+rHXiMzXVfDw6x1BJGiYqtCfW72X1L0DvRNE6WiVyQkEIxMbNd7hBQXOwGpF3Ne9/ GxKlQporK9yOl785+bRA867HxNB93nbBbc2kNCkLxClseJnPs0BwpiEEp8dAquVGgv jfqqbHXDorofg== Message-ID: <26f0d8edf8f2173a56e4a1345f2e4224658721d3.camel@kernel.org> Subject: Re: [PATCH v2] ceph: fix error handling in ceph_atomic_open and ceph_lookup From: Jeff Layton To: Ilya Dryomov Cc: Ceph Development Date: Tue, 22 Jun 2021 08:24:07 -0400 In-Reply-To: References: <20210603123850.74421-1-jlayton@kernel.org> <20210621235722.304689-1-jlayton@kernel.org> Content-Type: text/plain; charset="ISO-8859-15" User-Agent: Evolution 3.40.2 (3.40.2-1.fc34) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org On Tue, 2021-06-22 at 14:09 +0200, Ilya Dryomov wrote: > On Tue, Jun 22, 2021 at 1:57 AM Jeff Layton wrote: > > > > Commit aa60cfc3f7ee broke the error handling in these functions such > > that they don't handle non-ENOENT errors from ceph_mdsc_do_request > > properly. > > > > Move the checking of -ENOENT out of ceph_handle_snapdir and into the > > callers, and if we get a different error, return it immediately. > > > > Fixes: aa60cfc3f7ee ("ceph: don't use d_add in ceph_handle_snapdir") > > Signed-off-by: Jeff Layton > > --- > > fs/ceph/dir.c | 22 ++++++++++++---------- > > fs/ceph/file.c | 14 ++++++++------ > > fs/ceph/super.h | 2 +- > > 3 files changed, 21 insertions(+), 17 deletions(-) > > > > This one fixes the bug that Ilya spotted in ceph_atomic_open. Also, > > there is no need to test IS_ERR(dentry) unless we called > > ceph_handle_snapdir. Finally, it's probably best not to pass > > ceph_finish_lookup an ERR_PTR as a dentry. Reinstate the res pointer and > > only reset the dentry pointer if it's valid. > > > > diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c > > index 5624fae7a603..e78da771ec96 100644 > > --- a/fs/ceph/dir.c > > +++ b/fs/ceph/dir.c > > @@ -668,14 +668,13 @@ static loff_t ceph_dir_llseek(struct file *file, loff_t offset, int whence) > > * Handle lookups for the hidden .snap directory. > > */ > > struct dentry *ceph_handle_snapdir(struct ceph_mds_request *req, > > - struct dentry *dentry, int err) > > + struct dentry *dentry) > > { > > struct ceph_fs_client *fsc = ceph_sb_to_client(dentry->d_sb); > > struct inode *parent = d_inode(dentry->d_parent); /* we hold i_mutex */ > > > > /* .snap dir? */ > > - if (err == -ENOENT && > > - ceph_snap(parent) == CEPH_NOSNAP && > > + if (ceph_snap(parent) == CEPH_NOSNAP && > > strcmp(dentry->d_name.name, fsc->mount_options->snapdir_name) == 0) { > > struct dentry *res; > > struct inode *inode = ceph_get_snapdir(parent); > > @@ -742,7 +741,6 @@ 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; > > @@ -793,12 +791,16 @@ 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); > > - res = ceph_handle_snapdir(req, dentry, err); > > - if (IS_ERR(res)) { > > - err = PTR_ERR(res); > > - } else { > > - dentry = res; > > - err = 0; > > + if (err == -ENOENT) { > > + struct dentry *res; > > + > > + res = ceph_handle_snapdir(req, dentry); > > Stray space here, fixed in the branch. > Thanks! > > + 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) */ > > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > > index 7aa20d50a231..7c08f864694f 100644 > > --- a/fs/ceph/file.c > > +++ b/fs/ceph/file.c > > @@ -739,14 +739,16 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry, > > err = ceph_mdsc_do_request(mdsc, > > (flags & (O_CREAT|O_TRUNC)) ? dir : NULL, > > req); > > - dentry = ceph_handle_snapdir(req, dentry, err); > > - if (IS_ERR(dentry)) { > > - err = PTR_ERR(dentry); > > - goto out_req; > > + if (err == -ENOENT) { > > + dentry = ceph_handle_snapdir(req, dentry); > > + if (IS_ERR(dentry)) { > > + err = PTR_ERR(dentry); > > + goto out_req; > > + } > > + err = 0; > > } > > - err = 0; > > > > - if ((flags & O_CREAT) && !req->r_reply_info.head->is_dentry) > > + if (!err && (flags & O_CREAT) && !req->r_reply_info.head->is_dentry) > > err = ceph_handle_notrace_create(dir, dentry); > > > > if (d_in_lookup(dentry)) { > > I must admit that I don't understand the code that follows. For > example, if ceph_handle_notrace_create() returns ENOENT, is it supposed > to be resolved by ceph_finish_lookup()? Because if it gets resolved, > err is not reset and we still jump to out_req, possibly leaving some > dentry references behind. It appears to be an older bug though. > Yes. A lot of this code is unclear. > This fix for dealing with ceph_mdsc_do_request() errors seems correct, > but I really think this code needs massaging to disentangle handling of > special cases from actual errors. > > Reviewed-by: Ilya Dryomov > Thanks and I agree. This code really is a giant hairball. I really hate the way it weaves "err" through several functions and lets them deal with it. That alone makes this so very difficult to follow. I intend to follow up with some more cleanup in this area, but I haven't had the time to spend on it yet. In the meantime, if anyone else wants to submit patches to do this cleanup, I'm happy to review them... -- Jeff Layton