Tejun Heo wrote:

quoted text
> Greg KH wrote:

>> Why do we need ioctls?  For CUSE?  In that case, would we need to copy

>> the memory from userspace, into the kernel, and then back out into

>> userspace again?  Can't we just have a "pass-through" type fixed ioctl

>> instead?

>

> Can you elaborate a bit?  How the fixed ioctl would know how much to

> copy in and out and from where?

If you're worried about the double copying due to performance reasons,

what we can do is implementing userspace to userspace copying.  I just

took easier path of copying twice as u-u copy can't be done using the

existing FUSE mechanics, but frankly, at this point, I think that would

be an premature optimization.
--

tejun

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