ocfs2 sometimes needs to block signals around dlm operations, but it
currently does it with sigprocmask(). Even worse, it's checking the
error code of sigprocmask(). The in-kernel sigprocmask() can only error
if you get the SIG_* argument wrong. We don't.
Wrap the sigprocmask() calls with ocfs2_[un]block_signals(). These
functions are void, but they will BUG() if somehow sigprocmask() returns
an error.
Signed-off-by: Joel Becker <joel.becker@oracle.com>