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SubjectRe: [PATCH] Mounting on floating mounts is possible
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Björn Steinbrink wrote:
> Hi,
>
> this[1] patch changed check_mnt() so that mounting on a floating mount
> (i.e. one that was unmounted using MNT_DETACH and was still in use) is
> possible, since we no longer check if the mountpoint is actually
> reachable. The problem is that we may lose any reference to the floating
> mount, but the mount on it will keep it alive, thus it will never go
> away. The following patch removes the reference from the mount to its
> namespace when it is unmounted lazily, so that check_mnt protects from
> such mounts.
>
> Please CC me as I'm not subscribed to the list.
>
> Bjoern
>
> [1] http://lwn.net/Articles/91946/
>
> diff -uNr --minimal a/fs/namespace.c b/fs/namespace.c
> --- a/fs/namespace.c 2004-10-31 00:41:02.000000000 +0200
> +++ b/fs/namespace.c 2004-11-06 04:38:37.299013810 +0100
> @@ -358,6 +358,7 @@
> } else {
> struct nameidata old_nd;
> detach_mnt(mnt, &old_nd);
> + mnt->mnt_namespace = NULL;
> spin_unlock(&vfsmount_lock);
> path_release(&old_nd);
> }
> -

I don't think this patch clears mnt_namespace for the root of the
umounted tree. How about this?



- --
Mike Waychison
Sun Microsystems, Inc.
1 (650) 352-5299 voice
1 (416) 202-8336 voice

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namespace.c | 1 +
1 files changed, 1 insertion(+)

Index: linux-2.6.9-quilt/fs/namespace.c
===================================================================
--- linux-2.6.9-quilt.orig/fs/namespace.c 2004-11-08 11:18:39.980358880 -0500
+++ linux-2.6.9-quilt/fs/namespace.c 2004-11-08 11:19:24.702560072 -0500
@@ -352,6 +352,7 @@ void umount_tree(struct vfsmount *mnt)
mnt = list_entry(kill.next, struct vfsmount, mnt_list);
list_del_init(&mnt->mnt_list);
list_del_init(&mnt->mnt_fslink);
+ mnt->mnt_namespace = NULL;
if (mnt->mnt_parent == mnt) {
spin_unlock(&vfsmount_lock);
} else {
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