Messages in this thread | | | From | Andreas Gruenbacher <> | Subject | Re: [PATCH 1/5] fsnotify/vfsmount: add fsnotify fields to struct vfsmount | Date | Thu, 10 Dec 2009 17:31:42 +0100 |
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On Friday 04 December 2009 16:39:25 Christoph Hellwig wrote: > What's the rationale for adding them?
The idea is to provide a mechanism to watch for "all events", but in a namespace aware way: for that, a process registers interest in all mount points it can reach. With the previous hack, a global "I want it all" flag, per-namespace listeners were not possible.
Root can use bind mounts onto themselves (e.g., mount --bind /foo/bar /foo/bar) to watch arbitrary directories with the per-mount-point mechanism. Mount as user will open up additional use cases.
It would be nice to be able to register interest in all events below a directory which is not a mount point, too. The problem with that is that the number of cached inodes below a given directory could be huge -- and we would have to visit them all atomically in order to "mark" them, which is not feasible. The per-mount-point mechanism will eventually give us *almost* the same, and so I believe it's good enough.
Thanks, Andreas
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