... as the comments in reparent() clearly say. As it is, we reparent
*all* overmounts of the mounts being taken out, including those that
are taken out themselves. It's not only a potentially massive slowdown
(on a pathological setup we might end up with O(N^2) time for N mounts
being kicked out), it can end up with incorrect ->overmount in the
surviving mounts.
Fixes: f0d0ba19985d "Rewrite of propagate_umount()"
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
fs/pnode.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/pnode.c b/fs/pnode.c
index 81f7599bdac4..1c789f88b3d2 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -637,10 +637,11 @@ void propagate_umount(struct list_head *set)
}
// now to_umount consists of all acceptable candidates
- // deal with reparenting of remaining overmounts on those
+ // deal with reparenting of surviving overmounts on those
list_for_each_entry(m, &to_umount, mnt_list) {
- if (m->overmount)
- reparent(m->overmount);
+ struct mount *over = m->overmount;
+ if (over && !will_be_unmounted(over))
+ reparent(over);
}
// and fold them into the set
--
2.47.2
