zfsonlinux/zfs — pull request #715 by ryao (2012-05-02 12:39:11+00:00)
Title: Import support for O_EXCL from Illumos

Opening block devices with O_EXCL is meant to guarantee exclusive
access, but the current code does not honor this. This permitted
multiple applications can obtain file handles to zvols with
the O_EXCL flag set, which could cause problems.

The Illumos zvol implementation honors O_EXCL, so we modify our code to
match theirs.

Signed-off-by: Richard Yao