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    Subject[PATCH] namespace.c: fix bind mount from foreign namespace
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    Bind mount from a foreign namespace results in an un-removable mount.
    The reason is that mnt->mnt_namespace is copied from the old mount in
    clone_mnt(). Because of this, check_mnt() in sys_umount() will fail.

    The solution is to set mnt->mnt_namespace to current->namespace.

    clone_mnt() is either called from do_loopback() or copy_tree().
    copy_tree() is called from do_loopback() or copy_namespace().

    When called (directly or indirectly) from do_loopback(), always
    current->namspace is being modified: check_mnt(nd->mnt). So setting
    mnt->mnt_namespace to current->namspace is the right thing to do.

    When called from copy_namespace(), the setting of mnt_namespace is
    irrelevant, since mnt_namespace is reset later in that function for
    all copied mounts.

    Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>

    Index: linux/fs/namespace.c
    ===================================================================
    --- linux.orig/fs/namespace.c 2005-05-13 12:22:52.000000000 +0200
    +++ linux/fs/namespace.c 2005-05-13 12:32:36.000000000 +0200
    @@ -160,7 +160,7 @@ clone_mnt(struct vfsmount *old, struct d
    mnt->mnt_root = dget(root);
    mnt->mnt_mountpoint = mnt->mnt_root;
    mnt->mnt_parent = mnt;
    - mnt->mnt_namespace = old->mnt_namespace;
    + mnt->mnt_namespace = current->namespace;

    /* stick the duplicate mount on the same expiry list
    * as the original if that was on one */
    -
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