Messages in this thread | | | From | (Eric W. Biederman) | Date | Thu, 19 Jun 2008 20:39:44 -0700 | Subject | Re: [patch -mm 0/4] mqueue namespace |
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ebiederm@xmission.com (Eric W. Biederman) writes:
> One way to fix that is to add a hidden directory to the mnt namespace. > Where magic in kernel filesystems can be mounted. Only visible > with a magic openat flag. Then: > > fd = openat(AT_FDKERN, ".", O_DIRECTORY) > fchdir(fd); > umount("./mqueue", MNT_DETACH); > mount(("none", "./mqueue", "mqueue", 0, NULL); > > Would unshare the mqueue namespace. > > Implemented for plan9 this would solve a problem of how do you get > access to all of it's special filesystems. As only bind mounts > and remote filesystem mounts are available. For linux thinking about > it might shake the conversation up a bit.
Thinking about this some more. What is especially attractive if we do all namespaces this way is that it solves two lurking problems. 1) How do you keep a namespace around without a process in it. 2) How do you enter a container.
If we could land the namespaces in the filesystem we could easily persist them past the point where a process is present in one if we so choose.
Entering a container would be a matter of replacing your current namespaces mounts with namespace mounts take from the filesystem.
I expect performance would degrade in practice, but it is tempting to implement it and run a benchmark and see if we can measure anything.
Eric
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