commit 3815f1be546e752327b5868af103ccdddcc4db77 upstream. 'count' is how much you want written, not the final position. Moreover, it can legitimately be less than the current position... Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>