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Commit 7b8a53fd authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent b650c858

fs/namespace.c

+5 −3
Original line number Diff line number Diff line
@@ -1226,15 +1226,16 @@ void release_mounts(struct list_head *head) 
 */

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 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) 
		}

		change_mnt_propagation(p, MS_PRIVATE);

	}

	list_splice(&tmp_list, kill);

}



static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts);