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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 DC46AC43381 for ; Wed, 6 Mar 2019 04:36:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE77E20663 for ; Wed, 6 Mar 2019 04:36:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726699AbfCFEgI convert rfc822-to-8bit (ORCPT ); Tue, 5 Mar 2019 23:36:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:50074 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726655AbfCFEgI (ORCPT ); Tue, 5 Mar 2019 23:36:08 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E9709309264F; Wed, 6 Mar 2019 04:36:07 +0000 (UTC) Received: from colo-mx.corp.redhat.com (colo-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.20]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E08B417115; Wed, 6 Mar 2019 04:36:07 +0000 (UTC) Received: from zmail21.collab.prod.int.phx2.redhat.com (zmail21.collab.prod.int.phx2.redhat.com [10.5.83.24]) by colo-mx.corp.redhat.com (Postfix) with ESMTP id CC1F81819AFB; Wed, 6 Mar 2019 04:36:07 +0000 (UTC) Date: Tue, 5 Mar 2019 23:36:07 -0500 (EST) From: Jianhong Yin To: Steve Dickson Cc: "Jianhong.Yin" , linux-nfs@vger.kernel.org Message-ID: <569350425.9942929.1551846967676.JavaMail.zimbra@redhat.com> In-Reply-To: <813b5167-8c4a-dd64-eb95-d29b4463d54a@RedHat.com> References: <20190228050842.15827-1-yin-jianhong@163.com> <813b5167-8c4a-dd64-eb95-d29b4463d54a@RedHat.com> Subject: Re: [PATCH] mount.nfs: fix ignore EBUSY problem in special scenario MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.66.12.115, 10.4.195.23] Thread-Topic: mount.nfs: fix ignore EBUSY problem in special scenario Thread-Index: jdRtCuA1VfG89YCOAeyLwCeG4toh6w== X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Wed, 06 Mar 2019 04:36:07 +0000 (UTC) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org ----- 原始邮件 ----- > 发件人: "Steve Dickson" > 收件人: "Jianhong.Yin" > 抄送: linux-nfs@vger.kernel.org, jiyin@redhat.com > 发送时间: 星期三, 2019年 3 月 06日 上午 2:00:02 > 主题: Re: [PATCH] mount.nfs: fix ignore EBUSY problem in special scenario > > Hello, > > I apologies for taking so long to get to this... > > On 2/28/19 12:08 AM, Jianhong.Yin wrote: > > now mount.nfs ignore EBUSY when the $dir is a mountpoint, > > it's not correct in specail scenario for example: > > $dir is a mountpoint of other filesystem(let's say tmpfs) > > so we must be sure: current nfs mounting has mounted on $dir, then > > ignore the EBUSY for user. > > > > - if (errno == EBUSY && is_mountpoint(mi->node)) > > + if (errno == EBUSY && is_mountpoint(mi->node) && has_mounted_on(mi->spec, > > mi->node)) > > > > reproducer: > > ''' > > mkdir -p /expdir /mnt/nfsmp /mnt/tmpfs > > echo "/expdir *(rw,no_root_squash)" >/etc/exports > > service nfs restart > > mount -t tmpfs tmpfs /mnt/tmpfs > > mount -osharecache localhost:/expdir /mnt/nfsmp #success > > mount -osharecache localhost:/expdir /mnt/nfsmp #mounted already, return > > 0(pass) > > mount -osharecache localhost:/expdir /mnt/tmpfs #success > > mount -osharecache localhost:/expdir /mnt/tmpfs #mounted already, return > > 0(pass) > > umount /mnt/nfsmp > > umount /mnt/tmpfs > > > > mount -ocontext=system_u:object_r:xferlog_t:s0,sharecache localhost:/expdir > > /mnt/nfsmp > > mount -ocontext=system_u:object_r:user_home_dir_t:s0,sharecache > > localhost:/expdir /mnt/tmpfs > > [[ $? = 0 ]] && echo "***test fail: hasn't mounted, should return fail ***" > > > > umount /mnt/nfsmp > What real world problem is this solving or better yet what real world > situation would something like this be done?? > > I see this more of a pilot error... no one uses tmpfs to make mount to fail > (or not fail in this case)... It's just not how tmpfs is used. replace tmpfs with ext4/xfs ... will get same unexpected result. > > Plus who uses -ocontext= this way? If some one is that sophisticated to > use mount like that.... and get wrong... they need to be a little > more sophisticated ;-) > > Finally, when tmpfs is not in the picture things work as expected.... > > Maybe I'm missing something... I don't this as a problem or a situation > the people will run into... again... maybe I'm missing something. something you missing might be: "$Dir is a mountpoint" doesn't mean "$Dir has mounted on a nfs:/share you want" (it might be tmpfs/ext4/xfs/btrfs/... or another nfs that is not your expect) I know this test path is very ... abnormal. I just think I think the plane should not ignore "Landing gear failure"(EBUSY), even if the pilot did a very unconventional operation :) I'm just want you understand what will happen in this corner corner case. It's up to you(won't fix/or fix) Jianhong > > steved. > > ''' > > > > Signed-off-by: Jianhong Yin > > --- > > support/include/misc.h | 1 + > > support/misc/mountpoint.c | 26 +++++++++++++++++++++++++- > > utils/mount/stropts.c | 2 +- > > 3 files changed, 27 insertions(+), 2 deletions(-) > > > > diff --git a/support/include/misc.h b/support/include/misc.h > > index 06e2a0c..bd02bfc 100644 > > --- a/support/include/misc.h > > +++ b/support/include/misc.h > > @@ -19,6 +19,7 @@ char *generic_make_pathname(const char *, const char *); > > _Bool generic_setup_basedir(const char *, const char *, char *, const > > size_t); > > > > extern int is_mountpoint(char *path); > > +extern int has_mounted_on(const char *fsname, const char *dir); > > > > /* size of the file pointer buffers for rpc procfs files */ > > #define RPC_CHAN_BUF_SIZE 32768 > > diff --git a/support/misc/mountpoint.c b/support/misc/mountpoint.c > > index 9f9ce44..7f8a89f 100644 > > --- a/support/misc/mountpoint.c > > +++ b/support/misc/mountpoint.c > > @@ -3,9 +3,11 @@ > > * check if a given path is a mountpoint > > */ > > > > +#include > > #include > > -#include "xcommon.h" > > +#include > > #include > > +#include "xcommon.h" > > #include "misc.h" > > > > int > > @@ -38,3 +40,25 @@ is_mountpoint(char *path) > > free(dotdot); > > return rv; > > } > > + > > +int > > +has_mounted_on(const char *fsname, const char *dir) > > +{ > > + struct mntent *ent; > > + FILE *fp; > > + int ret = 0; > > + > > + fp = setmntent("/proc/mounts", "r"); > > + if (fp == NULL) { > > + perror("[unlikely] setmntent(3) fail"); > > + exit(1); > > + } > > + while (NULL != (ent = getmntent(fp))) { > > + if (!strcmp(ent->mnt_fsname, fsname) && !strcmp(ent->mnt_dir, dir)) { > > + ret = 1; > > + break; > > + } > > + } > > + endmntent(fp); > > + return ret; > > +} > > diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c > > index a093926..bffb74a 100644 > > --- a/utils/mount/stropts.c > > +++ b/utils/mount/stropts.c > > @@ -1081,7 +1081,7 @@ static int nfsmount_fg(struct nfsmount_info *mi) > > return EX_SUCCESS; > > > > #pragma GCC diagnostic ignored "-Wdiscarded-qualifiers" > > - if (errno == EBUSY && is_mountpoint(mi->node)) { > > + if (errno == EBUSY && is_mountpoint(mi->node) && > > has_mounted_on(mi->spec, mi->node)) { > > #pragma GCC diagnostic warning "-Wdiscarded-qualifiers" > > /* > > * EBUSY can happen when mounting a filesystem that > > >