Messages in this thread | | | Date | Thu, 11 Jan 2001 10:39:25 -0600 (CST) | From | Jesse Pollard <> | Subject | Re: FS callback routines |
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Daniel Phillips <phillips@innominate.de>: > Jamie Lokier wrote: > > > > Daniel Phillips wrote: > > > DN_OPEN A file in the directory was opened > > > > > > You open the top level directory and register for events. When somebody > > > opens a subdirectory of the top level directory, you receive > > > notification and register for events on the subdirectory, and so on, > > > down to the file that is actually modified. > > > > If it worked, and I'm not sure the timing would be reliable enough, the > > daemon would only have to have open every directory being accessed by > > every program in the system. Hmm. Seems like overkill when you're only > > interested in files that are being modified. > > It gets to close some too. Normally just the directories in the path to > the file(s) being modified would be open. > > Good point about the timing. A directory should not disappear before an > in-flight notification has been serviced. I doubt the current scheme > enforces this. There is no more room for 'works most of the time' in > this than there is in our memory page handling. > > > It would be much, much more reliable to do a walk over d_parent in > > dnotify.c. Your idea is a nice way to flag kernel dentries such that > > you don't do d_parent walks unnecessarily. > > It's bottom-up vs top-down. It's worth analyzing the top-down approach > a little more, it does solve a lot of problems (and creates some as you > pointed out, or at least makes some existing problems more obvious). > For make it's really quite nice. The make daemon only needs to register > in the top level directory of the source tree. I think this solves the > hard link problem too, because each path that's interested in > notification will receive it.
It makes security checks impossible though. You would have to reboot the system every time a directory changes permission to block unauthorized monitoring of files that are no longer accessable by the user.
------------------------------------------------------------------------- Jesse I Pollard, II Email: pollard@navo.hpc.mil
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