Re: Approaches to making io_submit not block

Christoph Hellwig
2011-09-01T16:05:01Z

On Thu, Sep 01, 2011 at 08:58:45AM -0700, Jeremy Allison wrote:
> Yes I did consider that of course. Problem is that leads you to the
> nightmare that is losing all fcntl locks on the file when any of the
> descriptors are closed. Of course we already have internal work arounds
> for that - but they're not scalable in this case. We'd have to dup on
> every read/write, and because of the fcntl lock problem we have to keep
> all fd's around until the final close of the file. Don't tell us to
> implement our own locking instead because (a) we already do in the case
> where we don't need locking consistency with NFS and (b) most vendors insist on
> locking consistency with NFS - not good if locks on one protocol aren't
> seen by another.

We could easily give you an fcntl / dup3 flag to only release posix
locks on the final close of a struct file if that helps you.