Re: file metadata via fs API

On Wed, 2020-08-12 at 14:06 +0100, David Howells wrote:

Miklos Szeredi [off-list ref] wrote:

quoted

That presumably means the mount ID <-> mount path mapping already
exists, which means it's just possible to use the open(mount_path,
O_PATH) to obtain the base fd.

No, you can't.  A path more correspond to multiple mounts stacked on
top of
each other, e.g.:

	mount -t tmpfs none /mnt
	mount -t tmpfs none /mnt
	mount -t tmpfs none /mnt

Now you have three co-located mounts and you can't use the path to
differentiate them.  I think this might be an issue in autofs, but
Ian would
need to comment on that.

It is a problem for autofs, direct mounts in particular, but also
for mount ordering at times when umounting a tree of mounts where
mounts are covered or at shutdown.

Ian