From mboxrd@z Thu Jan 1 00:00:00 1970 From: Harald Hoyer Subject: Re: [PATCH] switch_root: a better approach to subroots Date: Thu, 19 Nov 2009 09:19:05 +0100 Message-ID: <4B04FF79.90406@redhat.com> References: <20091118153312.16E989D404F@zog.reactivated.net> <20091118184706.GB23977@nb.net.home> <4B045586.1090906@redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4B045586.1090906-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: util-linux-ng-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Peter Jones Cc: Karel Zak , Daniel Drake , util-linux-ng-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, initramfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org On 11/18/2009 09:13 PM, Peter Jones wrote: > On 11/18/2009 01:47 PM, Karel Zak wrote: >> >> I think dracut guys should be in CC. Any objection against this change? >> >> On Wed, Nov 18, 2009 at 03:33:12PM +0000, Daniel Drake wrote: >>> This reverts commit a692a8745941a192528c5e2a05de97155ba586f9. >>> Booting into a system this way just leads to problems because >>> you cannot remount the root read-only at shutdown (leading to unclean >>> shutdowns). >>> >>> Miklos Szeredi pointed out a trick to turn any directory into a >>> mount point which avoids this problem. Therefore we can simplify >>> switch_root again and simply document that its users should set >>> up the root as a mount point beforehand. >>> --- >>> sys-utils/switch_root.8 | 13 +++++++ >>> sys-utils/switch_root.c | 81 +++-------------------------------------------- >>> 2 files changed, 18 insertions(+), 76 deletions(-) >>> >>> diff --git a/sys-utils/switch_root.8 b/sys-utils/switch_root.8 >>> index 4fdc8e9..b6712ec 100644 >>> --- a/sys-utils/switch_root.8 >>> +++ b/sys-utils/switch_root.8 >>> @@ -32,6 +32,19 @@ show version number and exit >>> .B switch_root >>> returns 0 on success and 1 on failure. >>> >>> +.SH NOTES >>> +switch_root will fail to function if >>> +.B newroot >>> +is not the root of a mount. If you want to switch root into a directory that >>> +does not meet this requirement then you can first use a bind-mounting trick to >>> +turn any directory into a mount point: >>> +.sp >>> +.nf >>> +.RS >>> +mount --bind $DIR $DIR >> >> Cannot we add this functionality directly to the switch_root command? >> I mean call: >> >> mount --bind /newroot/subroot /newroot/subroot >> mount --move /newroot/subroot / >> >> Now we have: >> >> mount --move newroot / >> chroot /newroot/subroot > > That certainly seems preferable to reverting the patch, especially if, as > the original commit log says, some distro (OLPC in this case) is actually > using this functionality. > no objections -- To unsubscribe from this list: send the line "unsubscribe util-linux-ng" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html