LinuxQuestions.org - error using O_DIRECT starting with kernel 3.16.0 (?)

I have a program that uses the following open() flags:

Code:

O_RDONLY+O_NOATIME+O_LARGEFILE+O_DIRECT

read() calls work OK until EOF is reached and then an EINVAL error is returned.

The buffer is aligned with the following call:

Code:

posix_memalign((void**) &vbuff,512,BIOCC);

The program runs OK if O_DIRECT is removed.
The program has been running for years on earlier kernel versions.

Is this a bug or an API change? Need guidance.

O_DIRECT is used because the file is being read to verify integrity shortly after it was written, so reading from the cache is not wanted.
This is part of a backup utility.