Re: [PATCH] fs/namei.c: Hard link and rename should check same device instead of same mount

[Jordi Pujol Palomer <jordipujolp@gmail.com>]

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El Sun, 20 Mar 2016 18:22:51 +0000
Al Viro <viro@ZenIV.linux.org.uk> escrigué:

> ... until you consider the fun of moving subtrees between different
> mounts. IMO it's a bloody bad idea; semantics would be hard to
> define, not to mention that things that used to be on the same fs
> might eventually get moved to different ones, and for those there's
> obviously no way to do link(2) or rename(2) at all.
> 
Well I'm not an expert,
think the boundary option should be only for bind mounts, and will
work only when the filesystem supports it, as usual by now. The
mountpoint can be moved, but the underlying device continues being the
same; but sure it is more complicated, I understand,

> What are you actually trying to achieve?  There might be saner ways
> to do it...
Yes, now I see that the all the local bind may be replaced with symbolic
links,

# mount-list > mount-list.txt

Thanks for your attention,

Jordi Pujol i Palomer
Enginyer Tècnic Industrial

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sysfs	/sys	sysfs	nodev,noexec,nosuid,relatime,rw	sysfs	0:17
proc	/proc	proc	nodev,noexec,nosuid,relatime,rw	proc	0:5
udev	/dev	devtmpfs	mode=755,nosuid,nr_inodes=978001,relatime,rw,size=3912004k	udev	0:6
devpts	/dev/pts	devpts	gid=5,mode=620,noexec,nosuid,ptmxmode=000,relatime,rw	devpts	0:14
tmpfs	/run	tmpfs	mode=755,noexec,nosuid,relatime,rw,size=786088k	tmpfs	0:18
tmpfs	/lnet	tmpfs	mode=755,relatime,rw,size=7860880k	tmpfs	0:19
/dev/sda1	/lnet/image	ext2	errors=continue,noacl,noatime,nouser_xattr,ro	/dev/sda1	8:1
/lnet/image/LneTLXQT64/00filesystem.squashfs	/lnet/00filesystem.squashfs	squashfs	noatime,ro,loop=/dev/loop0	/dev/loop0	7:0
/lnet/image/LneTLXQT64/10interfaces.squashfs	/lnet/10interfaces.squashfs	squashfs	noatime,ro,loop=/dev/loop1	/dev/loop1	7:1
/dev/sda2	/lnet/cowroot	ext4	data=ordered,relatime,rw	/dev/sda2	8:2
overlay	/	overlay	lowerdir=/lnet/00filesystem.squashfs:/lnet/10interfaces.squashfs,relatime,rw,upperdir=/lnet/cowroot/LneTLXQTCOW/upper,workdir=/lnet/cowroot/LneTLXQTCOW/work	overlay	0:20
tmpfs	/tmp	tmpfs	nodev,nosuid,relatime,rw,size=7860880k,mode=1777	tmpfs	0:21
tmpfs	/var/log	tmpfs	mode=755,nosuid,relatime,rw,size=7860880k	tmpfs	0:22
tmpfs	/var/tmp	tmpfs	nodev,nosuid,relatime,rw,size=7860880k,mode=1777	tmpfs	0:23
securityfs	/sys/kernel/security	securityfs	nodev,noexec,nosuid,relatime,rw	securityfs	0:16
tmpfs	/dev/shm	tmpfs	nodev,nosuid,rw,mode=1777	tmpfs	0:24
tmpfs	/run/lock	tmpfs	nodev,noexec,nosuid,relatime,rw,size=5120k,mode=1777	tmpfs	0:25
tmpfs	/sys/fs/cgroup	tmpfs	mode=755,nodev,noexec,nosuid,ro	tmpfs	0:26
cgroup	/sys/fs/cgroup/systemd	cgroup	name=systemd,nodev,noexec,nosuid,relatime,release_agent=/lib/systemd/systemd-cgroups-agent,rw,xattr	cgroup	0:27
pstore	/sys/fs/pstore	pstore	nodev,noexec,nosuid,relatime,rw	pstore	0:28
cgroup	/sys/fs/cgroup/cpu	cgroup	cpu,nodev,noexec,nosuid,relatime,rw	cgroup	0:29
systemd-1	/proc/sys/fs/binfmt_misc	autofs	direct,fd=27,maxproto=5,minproto=5,pgrp=1,relatime,rw,timeout=0	systemd-1	0:30
hugetlbfs	/dev/hugepages	hugetlbfs	relatime,rw	hugetlbfs	0:31
mqueue	/dev/mqueue	mqueue	relatime,rw	mqueue	0:15
debugfs	/sys/kernel/debug	debugfs	relatime,rw	debugfs	0:7
/lnet/image/LneTLXQT64	/boot	none	ro,bind	/dev/sda1	8:1
/lnet/cowroot/LneTXFCEhome	/home	none	rw,bind	/dev/sda2	8:2
/lnet/cowroot/JPLive	/home/JPLive	none	rw,bind	/dev/sda2	8:2
/lnet/cowroot/JPLive	/lnet/cowroot/LneTXFCEhome/JPLive	none	rw,bind	/dev/sda2	8:2
/lnet/image/grub	/boot/grub	none	ro,bind	/dev/sda1	8:1
/lnet/image/grub	/lnet/image/LneTLXQT64/grub	none	ro,bind	/dev/sda1	8:1
/lnet/cowroot/JPLive/var-spool	/var/spool	none	rw,bind	/dev/sda2	8:2
/lnet/cowroot/LneTXFCEhome/root	/root	none	rw,bind	/dev/sda2	8:2
/lnet/cowroot/JPLive/apt-lib-amd64	/var/lib/apt	none	rw,bind	/dev/sda2	8:2
/lnet/cowroot/JPLive/apt-cache-amd64	/var/cache/apt	none	rw,bind	/dev/sda2	8:2
tmpfs	/run/user/1001	tmpfs	gid=100,mode=700,nodev,nosuid,relatime,rw,size=786088k,uid=1001	tmpfs	0:34