On Wed, Mar 31, 2010 at 01:04, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > Kay Sievers <kay.sievers@xxxxxxxx> writes: >> On Tue, Mar 30, 2010 at 20:30, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: >>> >>> The main short coming of using multiple network namespaces today >>> is that only network devices for the primary network namespaces >>> can be put in the kobject layer and sysfs. >>> >>> This is essentially the earlier version of this patchset that was >>> reviewed before, just now on top of a version of sysfs that doesn't >>> need cleanup patches to support it. >> >> Just to check if we are not in conflict with planned changes, and how >> to possibly handle them: >> >> There is the plan and ongoing work to unify classes and buses, export >> them at /sys/subsystem in the same layout of the current /sys/bus/. >> The decision to export buses and classes as two different things >> (which they aren't) is the last major piece in the sysfs layout which >> needs to be fixed. > > Interesting. We will symlinks ie: > /sys/class -> /sys/subsystem > /sys/bus -> /sys/subsystem > to keep from breaking userspace. Yeah, /sys/bus/, which is the only sane layout of the needlessly different 3 versions of the same thing (bus, class, block). /sys/bus/<subsys> can just be a plain symlinks to the /sys/subsystem/<subsys> directories. /sys/class/<subsys> *could* be a symlink to the /sys/subsystem/<subsys>/devices/ directory, but we really don't want to continue to stupidly mix subsystem-wide control files with device lists anymore. The "devices" directory needs to be a strict list of devices, not some collection of random stuff, that it is today. :) So we either leave all the conceptually broken class attributes behind us, and put them at the /sys/subsystem/<subsys>/ level only, or we need to create the /sys/class/<subsys>/* stuff all as symlinks like we do today. I expect, we have to create /sys/class as we do today. Another problem to solve is that sysfs does not allow us to symlink regular files, only directories, so we can currently not create the class-wide attributes as symlinks to the proper file in /sys/subsystem/. >> It would mean that /sys/subsystem/net/devices/* would look like >> /sys/class/net/* today. But at the /sys/subsystem/net/ directory could >> be global network-subsystem-wide control files which would need to be >> namespaced too. (The network subsystem does not use subsytem-global >> files today, but a bunch of other classes do.) >> >> This could be modeled into the current way of doing sysfs namespaces? >> A /sys/bus/<subsystem>/ directory hierarchy would need to be >> namespaced, not just a single plain directory with symlinks. Would >> that work? > > I'm not entirely clear on what you are doing but it all sounds like it > will fit within what I am doing. The goal is to unify the 3 needlessly different versions of "device lists of the same subsystem". We have /sys/class, /sys/bus, /sys/block, and all of them will be unified at /sys/subsystem/ leaving the old names as compat links only. Unlike block and class, the /sys/subsystem/<subsys> directory can be extended with custom subdirectories and files, without mixing random files into device lists. With /sys/subsystem/, userspace can uniquely identify and find all devices at /sys/<subsys>/devices/<device-name>/ with only the subsystem and the device name. All devices in /sys/devices already have a symlink called "subsystem" which will point back to the corresponding /sys/subsystem/<subsys> directory, and the event environment already contains a variable SUBSYSTEM with the name. That would be the first time sysfs device interfaces have some idea of consistency. :) > Right now I have /sys/class/net, > /sys/devices/virtual/net and a bunch of other net directories becoming > tagged and only showing up in the appropriately mounted sysfs. We > track them all in the class kset and as long as we extend that capability > when the subsystem change happens in sysfs all should be well. Ok, sounds good. > Today we have /sys/class/net/bonding_master. For now I have that as > an untagged but the implementation is aware of which network namespace > your current process is in. Thinking about that a little more it > would be better to make that file tagged so that userspace can see > different versions for the different network namespaces. Joy. Yeah, that might make more sense in the end. > I expect other control files will be the same. Sounds like, yes. > In general it doesn't make sense to add control files for networking. > as they easily conflict with legal network device names and thus create > the possibility of breaking someones userspace. Yeah, it did not makes sense it the first place to mix devices lists with global attributes. It's a real mess what people do in sysfs. Thanks, Kay -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
