On Tue, 18 Apr 2023, Jeff Layton wrote: > > The last thing we want in that case is for the server to decide to > change some intermediate dentry in between the two operations. Best > case, you'll get back ENOENT or something when the pathwalk fails. Worst > case, the server swaps what are two different mountpoints on your client > and you unmount the wrong one. Actually, the last think I want is for the server to do something that causes a directory to be invalidated (d_invalidate()). Then any mount points below there get DETACHed and we lose any change to use MNT_FORCE or to wait for the unmount to complete. Of course this can also happen during any other access, not just umount.... > > If we don't revaliate, then we're no worse off, and may be better off if > something hinky happens to the server of an intermediate dentry in the > path. Exactly. If we don't revalidate we might use old data, but it will be old data that were were allowed to access. It might be data that we are not now allowed to access, but it will never be new data that were have never been allowed to access. Thanks, NeilBrown
