Al Viro <viro@xxxxxxxxxxxxxxxxxx> wrote: > 3) normally, readlink(2) fails for non-symlinks. Moreover, according to > POSIX it should do so (with -EINVAL). There is a pathological case when > it succeeds for a directory, though. Namely, one of the kinds of AFS > "mountpoints". All AFS mountpoints are magic symlinks that are specially interpreted by the client as far as I'm aware. I'm not sure why the designers didn't just select a different file type for them, but they didn't. Unfortunately, it means that iget has to read the contents of the symlinks :-/ > stat(2) reports those as directories, stepping into them leads to > automounting a directory there (why do we have ->open() for them, BTW?). I think I put that in to make sure the open() syscall returned EREMOTE rather than another error if you tried to open it. It can probably be removed because with the d_automount code you can't ever get there I think - unless you can pass AT_NO_AUTOMOUNT to openat(). > How the hell is userland supposed to guess to call readlink(2) on those > suckers to get the information of what'll get automounted there if we step > upon them? There's an AFS userspace command that could be used to query a mountpoint that was going to use it. However, I suspect readlink() will now always trigger the automount. This is one of the things OpenAFS uses pioctl() for - but since I'm not allowed to add that to the kernel, I have to find some other way of doing it. > And could we please get rid of that kludge? David? Sure. 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
