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=-9.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 D7F18C433E2 for ; Tue, 15 Sep 2020 15:43:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E35720872 for ; Tue, 15 Sep 2020 15:43:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727442AbgIOPmi (ORCPT ); Tue, 15 Sep 2020 11:42:38 -0400 Received: from static.214.254.202.116.clients.your-server.de ([116.202.254.214]:45346 "EHLO ciao.gmane.io" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727429AbgIOPmT (ORCPT ); Tue, 15 Sep 2020 11:42:19 -0400 Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kID0C-0000tB-GH for linux-raid@vger.kernel.org; Tue, 15 Sep 2020 17:36:16 +0200 X-Injected-Via-Gmane: http://gmane.org/ To: linux-raid@vger.kernel.org From: "Andrey Jr. Melnikov" Subject: Re: [PATCH V2 1/2] Check hostname file empty or not when creating raid device Date: Tue, 15 Sep 2020 18:27:29 +0300 Message-ID: References: <1600155882-4488-1-git-send-email-xni@redhat.com> <1600155882-4488-2-git-send-email-xni@redhat.com> User-Agent: tin/2.2.1-20140504 ("Tober an Righ") (UNIX) (Linux/4.4.66-bananian (armv7l)) Sender: linux-raid-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Xiao Ni wrote: > If /etc/hostname is empty and the hostname is decided by network(dhcp, e.g.), there is a > risk that raid device will not be in active state after boot. It will be auto-read-only > state. It depends on the boot sequence. If the storage starts before network. The system > detects disks first, udev rules are triggered and raid device is assemble automatically. > But the network hasn't started successfully. So mdadm can't get the right hostname. The > raid device will be treated as a foreign raid. > Add a note message if /etc/hostname is empty when creating a raid device. > Signed-off-by: Xiao Ni > --- > mdadm.c | 3 +++ > mdadm.h | 1 + > util.c | 19 +++++++++++++++++++ > 3 files changed, 23 insertions(+) > diff --git a/mdadm.c b/mdadm.c > index 1b3467f..e551958 100644 > --- a/mdadm.c > +++ b/mdadm.c > @@ -1408,6 +1408,9 @@ int main(int argc, char *argv[]) > if (c.homehost == NULL && c.require_homehost) > c.homehost = conf_get_homehost(&c.require_homehost); > if (c.homehost == NULL || strcasecmp(c.homehost, "") == 0) { > + if (check_hostname()) > + pr_err("Note: The file /etc/hostname is empty. There is a risk the raid\n" > + " can't be active after boot\n"); > if (gethostname(sys_hostname, sizeof(sys_hostname)) == 0) { > sys_hostname[sizeof(sys_hostname)-1] = 0; > c.homehost = sys_hostname; > diff --git a/mdadm.h b/mdadm.h > index 399478b..3ef1209 100644 > --- a/mdadm.h > +++ b/mdadm.h > @@ -1480,6 +1480,7 @@ extern int parse_cluster_confirm_arg(char *inp, char **devname, int *slot); > extern int check_ext2(int fd, char *name); > extern int check_reiser(int fd, char *name); > extern int check_raid(int fd, char *name); > +extern int check_hostname(void); > extern int check_partitions(int fd, char *dname, > unsigned long long freesize, > unsigned long long size); > diff --git a/util.c b/util.c > index 579dd42..de5bad0 100644 > --- a/util.c > +++ b/util.c > @@ -694,6 +694,25 @@ int check_raid(int fd, char *name) > return 1; > } > > +/* It checks /etc/hostname has value or not */ > +int check_hostname() > +{ > + int fd, ret = 0; > + char buf[256]; > + > + fd = open("/etc/hostname", O_RDONLY); > + if (fd < 0) { > + ret = 1; > + goto out; > + } > + > + if (read(fd, buf, sizeof(buf)) == 0) > + ret = 1; Why not use stat() here, since you don't use file content? Also, any error from read() - mean file "not empty". This is right? > +out: > + close(fd); > + return ret; > +} > + > int fstat_is_blkdev(int fd, char *devname, dev_t *rdev) > { > struct stat stb;