fix old umount_tree() breakage
Expiry-related code calls umount_tree() several times with
the same list to collect vfsmounts to. Which is fine, except
that umount_tree() implicitly assumed that the list would
be empty on each call - it moves the victims over there and
then iterates through the list kicking them out. It's *almost*
idempotent, so everything nearly worked. However, mnt->ghosts
handling (and thus expirability checks) had been broken - that
part was not idempotent...
The fix is trivial - use local temporary list, splice it to
the the collector list when we are through.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index bfcb701..d7fc05f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1226,15 +1226,16 @@
*/
void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
{
+ LIST_HEAD(tmp_list);
struct vfsmount *p;
for (p = mnt; p; p = next_mnt(p, mnt))
- list_move(&p->mnt_hash, kill);
+ list_move(&p->mnt_hash, &tmp_list);
if (propagate)
- propagate_umount(kill);
+ propagate_umount(&tmp_list);
- list_for_each_entry(p, kill, mnt_hash) {
+ list_for_each_entry(p, &tmp_list, mnt_hash) {
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
@@ -1246,6 +1247,7 @@
}
change_mnt_propagation(p, MS_PRIVATE);
}
+ list_splice(&tmp_list, kill);
}
static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);