On 10/28/2014 06:33 PM, Eric W. Biederman wrote: > > Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> Thanks, Eric. Again, sorry for the delay. I've applied this patch. Cheers, Michael > --- > man2/umount.2 | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/man2/umount.2 b/man2/umount.2 > index aea39d8306fe..a0120b2fc811 100644 > --- a/man2/umount.2 > +++ b/man2/umount.2 > @@ -97,6 +97,24 @@ Don't dereference > if it is a symbolic link. > This flag allows security problems to be avoided in set-user-ID-\fIroot\fP > programs that allow unprivileged users to unmount filesystems. > + > +.P > +Shared mount points cause any mount activity on that mount point > +including umounts to be forwarded to every shared mount point in it's > +peer group and every slave mount of that peer group. This means that > +umount of any peer in a set of shared mounts will cause all of it's > +peers to be unmounted and all of their slaves to be unmounted as well. > + > +This propogagtion of unmount activity can be particularly surprising > +on systems where every mount point is shared by default. On such > +systems recursively bind mounting the root directory of the filesystem > +onto a subdirectory and then later unmounting that subdirectory with > +.BR MNT_DETACH > +will cause every mount in the mount namespace to be lazily unmounted. > + > +To ensure umount does not propagate the mount point may be > +remounted with MS_REC | MS_PRIVATE prior to umount being called. > + > .SH RETURN VALUE > On success, zero is returned. > On error, \-1 is returned, and > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
