| Message ID | 20160316140514.778db799@localdomain (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Mar 16, 2016 at 02:05:14PM +0100, Jordi Pujol Palomer wrote: > Hello, > > Working on a Linux system that bind mounts some > directories, have found frequent errors when moving files between > directories that belong to different mount points but are on the same > device. > The two attached patches solve these problems on a local filesystem. > Maybe we must test it on different configurations. NAK. This is absolutely deliberate; moreover, mount --bind $DIR $DIR is often used just to set such a boundary. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
El Wed, 16 Mar 2016 14:25:16 +0000 Al Viro <viro@ZenIV.linux.org.uk> escrigué: > NAK. This is absolutely deliberate; moreover, mount --bind $DIR $DIR > is often used just to set such a boundary. It means that the way I have proposed may work also ? Therefore we can develop a new option for binding to let the superuser choose what is needed for every mount-bind, example: mount --bind -o boundary $DIR $DIR mount --bind -o noboundary $DIR1 $DIR2 and allow remount also, mount -o remount,boundary $DIR mount -o remount,noboundary $DIR That seems feasible, Jordi Pujol i Palomer Enginyer Tècnic Industrial -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sun, Mar 20, 2016 at 07:06:25PM +0100, Jordi Pujol Palomer wrote: > Therefore we can develop a new option for binding to let the superuser > choose what is needed for every mount-bind, example: > > mount --bind -o boundary $DIR $DIR > > mount --bind -o noboundary $DIR1 $DIR2 > > and allow remount also, > > mount -o remount,boundary $DIR > > mount -o remount,noboundary $DIR > > That seems feasible, ... 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. What are you actually trying to achieve? There might be saner ways to do it... -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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 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
Signed-off-by: Jordi Pujol Palomer <jordipujolp@gmail.com> --- Subject: fs: Rename must check same device instead of same mount Date: Wed, 16 Mar 2016 09:12:21 +0100 --- linux-4.5.0-a/fs/namei.c +++ linux-4.5.0-b/fs/namei.c 2016-03-15 22:15:03.275460823 +0100 @@ -4424,7 +4424,7 @@ retry: } error = -EXDEV; - if (old_path.mnt != new_path.mnt) + if (old_path.dentry->d_sb->s_dev != new_path.dentry->d_sb->s_dev) goto exit2; error = -EBUSY;