Joel Becker <Joel.Becker@xxxxxxxxxx> wrote: > > On Sun, Sep 04, 2005 at 12:28:28AM -0700, Andrew Morton wrote: > > If there is already a richer interface into all this code (such as a > > syscall one) and it's feasible to migrate the open() tricksies to that API > > in the future if it all comes unstuck then OK. > > That's why I asked (thus far unsuccessfully): > > I personally was under the impression that "syscalls are not > to be added". We add syscalls all the time. Whichever user<->kernel API is considered to be most appropriate, use it. > I'm also wary of the effort required to hook into process > exit. I'm not questioning the use of a filesystem. I'm questioning this overloading of normal filesystem system calls. For example (and this is just an example! there's also mknod, mkdir, O_RDWR, O_EXCL...) it would be more usual to do fd = open("/sys/whatever", ...); err = sys_dlm_trylock(fd); I guess your current implementation prevents /sys/whatever from ever appearing if the trylock failed. Dunno if that's valuable. > Not to mention all the lifetiming that has to be written again. > On top of that, we lose our cute ability to shell script it. We > find this very useful in testing, and think others would in practice. > > > Are you saying that the posix-file lookalike interface provides > > access to part of the functionality, but there are other APIs which are > > used to access the rest of the functionality? If so, what is that > > interface, and why cannot that interface offer access to 100% of the > > functionality, thus making the posix-file tricks unnecessary? > > I thought I stated this in my other email. We're not intending > to extend dlmfs. Famous last words ;) > It pretty much covers the simple DLM usage required of > a simple interface. The OCFS2 DLM does not provide any other > functionality. > If the OCFS2 DLM grew more functionality, or you consider the > GFS2 DLM that already has it (and a less intuitive interface via sysfs > IIRC), I would contend that dlmfs still has a place. It's simple to use > and understand, and it's usable from shell scripts and other simple > code. (wonders how to do O_NONBLOCK from a script) I don't buy the general "fs is nice because we can script it" argument, really. You can just write a few simple applications which provide access to the syscalls (or the fs!) and then write scripts around those. Yes, you suddenly need to get a little tarball into users' hands and that's a hassle. And I sometimes think we let this hassle guide kernel interfaces (mutters something about /sbin/hotplug), and that's sad. -- Linux-cluster@xxxxxxxxxx http://www.redhat.com/mailman/listinfo/linux-cluster