Re: [PATCH 5/6] nfs: check all iov segments for correct memory access rights

Chuck Lever
2006-05-19T19:36:47Z

Andrew Morton wrote:
>> + if (unlikely(!access_ok(type, buf, len))) {
>> + retval = -EFAULT;
>> + goto out;
>> + }
>
> Now what's up here? Why does NFS, at this level, care about the page's
> virtual address? get_user_pages() will handle that?

I guess I'm not clear on what behavior is desired for scatter/gather if
one of the segments in an iov fails.

If one of the iov's will cause an EFAULT, how is that reported back to
the application, and what happens to the I/O being requested in the
other segments of the vector? When do we use an "all or nothing"
semantic, and when is it OK for some segments to fail?

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