nfs: don't zero out the rest of the page if we hit the EOF on a DIO READ
Eryu provided a test program that would segfault when attempting to read past the EOF on file that was opened O_DIRECT. The buffer given to the read() call was on the stack, and when he attempted to read past it it would scribble over the rest of the stack page. If we hit the end of the file on a DIO READ request, then we don't want to zero out the rest of the buffer. These aren't pagecache pages after all, and there's no guarantee that the buffers that were passed in represent entire pages. Cc: <stable@vger.kernel.org> # v3.5+ Cc: Fred Isaman <iisaman@netapp.com> Reported-by: Eryu Guan <eguan@redhat.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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