Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > (2) We can use the file position to represent the mnt_id and can jump to > > it directly - ie. using seek() to jump to a mount object by its ID. > > What happens if the mount at the current position is removed? umount_tree() requires the namespace_sem to be writelocked, so that should be fine as the patches currently read-lock that whilst doing /proc/*/mount* I'm assuming that kern_unmount() won't be a problem as it is there to deal with mounts made by kern_mount() which don't get added to the mount list (mnt_ns is MNT_NS_INTERNAL). kern_unmount_array() seems to be the same because overlayfs gives it mounts generated by clone_private_mount(). It might be worth putting a WARN_ON() in kern_unmount() to require this. When reading through proc, m_start() calls xas_find() which returns the entry at the starting index or, if not present, the next higher entry. David
