On Tue, Aug 12, 2008 at 10:18:49AM -0700, Linus Torvalds wrote:
> If we actually want to change the readdir() thing, then we should just
> make the rule be:
>
> - if the callback returns a non-zero value, the filesystem "readdir()"
> function should return that value (right now they are taught to return
> zero, and return errors on internal fatal things). And get rid of
> "buf.error" entirely.
Doesn't work well for readdir(2)...
> error = vfs_readdir(file, filldir, &buf);
> lastdirent = buf.previous;
> if (lastdirent) {
> error = count - buf.count;
> if (put_user(file->f_pos, &lastdirent->d_off))
> error = -EFAULT;
> }
> fput(file);
> return error;
>
> and we wouldn't need any other logic at all.
you've just lost e.g. -EIO for getdents(). And if you bail out on
non-zero return value from vfs_readdir(), you are back to -EINVAL
on full buffer.
Frankly, I'd rather keep ->readdir() instances simpler. There are far
more of those, for one thing. As it is, we only have "stop"/"continue"
->readdir() has to care about...
There's one more thing in that mess: a bunch of vfs_readdir() callers
end up playing very sick games to make sure they get the entire
directory. The trick is to find whether the damn thing has reached
the end; as it is, there are instances of ->readdir() that do _not_
(e.g. call filldir only once and let the caller repeat).
I'm certainly not too fond of buf->error. If you see a better interface
I'd love to hear about it, but I don't think that "just return anything
non-zero we'd got from callback" is going to be good. And if we go for
flagday changes in ->readdir(), we'd better get it right...
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