Messages in this thread | | | Subject | Re: file metadata via fs API | From | Ian Kent <> | Date | Thu, 13 Aug 2020 09:01:31 +0800 |
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On Wed, 2020-08-12 at 14:06 +0100, David Howells wrote: > Miklos Szeredi <miklos@szeredi.hu> wrote: > > > 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
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