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mount: don't destruct an external mount-namespace (v2)

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If a parent mount point is shared with exteranl mntns, a child will be
umounted from the external mntns too.

For example:
$ mount -t tmpfs xxx /root/tmp/
$ mount --make-shared tmp
$ mkdir tmp/xxx
$ mount -t tmpfs xxx /root/tmp/xxx
$ touch tmp/xxx/a

$ unshare -m umount tmp/xxx
$ ls -l tmp/xxx/a
ls: cannot access tmp/xxx/a: No such file or directory

This patch changes a parent mnt to private for umounting childrens.

v2: exit if a mount point can not be marked ad private

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Andrey Vagin 2013-07-05 12:19:54 +04:00 committed by Pavel Emelyanov
parent 714443d96f
commit 7aaef1ee4f
1 changed files with 5 additions and 0 deletions
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5
mount.c
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@ -590,6 +590,11 @@ static int do_umount_one(struct mount_info *mi)
if (!mi->parent)
return 0;
if (mount("none", mi->parent->mountpoint, "none", MS_REC|MS_PRIVATE, NULL)) {
pr_perror("Can't mark %s as private", mi->parent->mountpoint);
return -1;
}
if (umount(mi->mountpoint)) {
pr_perror("Can't umount at %s", mi->mountpoint);
return -1;