#8 get_permit failures

[Robert Read]

If a get permit call fails during a file open, then
EROFS is returned to the calling process, and can
produce errors that look like this:

cp: cannot create directory
`/mnt/server/doc/caching-nameserver-7.2': Read-only
file system
cp: cannot create directory
`/mnt/server/doc/imap-2000c': Read-only file system
cp: cannot create directory
`/mnt/server/doc/procmail-3.21': Read-only file system
cp: cannot create directory
`/mnt/server/doc/cyrus-sasl-1.5.24': Read-only file system

The correct way to handle this is put the process to
sleep until the permit is received.