Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > Implement the pioctl() system call. This is used to support a number of AFS > > functions, and could also be used for Coda and other filesystems. > > Umm, adding a new system call multiplexer without any structure is a > serious no-go. And this one is much worse than ioctl, which with a > fixed [fd,cmd,arg] tuple seems like a stronhold of sanity compred to this > monster with multiple arguments and a path that may or may not be there. Ummm... pioctl() has lots of structure. Standard argument/reply block definition, for example: you get one blob of argument, you may return one blob of argument, you must structure your blobs such that 32-bit/64-bit compatibility problems don't occur. It's _much_ more structured than ioctl, for example. The main annoyance with it, as you noted, is the fact that people have treated the path as being optional. > I think you'd be better of writing tools that use a sane interface than > adding a big pile of crap like this to the kernel. Name a single sane interface that can do all that pioctl() can? There isn't one. You can emulate almost all of pioctl() in userspace by a combination of getxattr, lgetxattr, setxattr, lsetxattr, add_key, keyctl_read, and when all else fails, open/open-NOFOLLOW + ioctl [IF not a dev file, and IF there are no collisions between ioctl numbers and pioctl numbers]. In other words, a mess. Now, assuming I do produce such a userspace library - that does not address the other requirement: that of using a common set of binaries to manipulate both OpenAFS and kAFS without the need for recompilation. I presume you advocate making OpenAFS change to suit your requirements? David -- 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
