fusefrontend: I/O error instead of panic on all-zero nonce

Running xfstests generic/075 on tmpfs often triggered a panic
for what seems to be a tmpfs bug.

Quoting from the email to lkml,
http://www.spinics.net/lists/kernel/msg2370127.html :

	tmpfs seems to be incorrectly returning 0-bytes when reading from
	a file that is concurrently being truncated.

0 files changed, 0 insertions, 0 deletions