posix locking and the brlock database

Volker Lendecke Volker.Lendecke at SerNet.DE
Sat May 19 10:03:17 GMT 2007

On Sat, May 19, 2007 at 07:43:53PM +1000, tridge at samba.org wrote:
> While the file is locked, a windows client tries to get the lock. It
> will check the posix lock in brlock.c, and see that it can't get the
> lock, so it puts in a pending lock entry in the brlock.tdb record for
> that file.
> Then the NFS client or local unix application releases the byte range
> lock. What triggers the retry of the pending lock? We don't get any
> notification from the kernel, and we don't retry internally.
> This is only a problem for timed locks with long timeouts of
> course. They aren't common, but it would be nice to handle them.
> Perhaps we need a timer which re-scans our pending lock list and
> retries those that were denied by posix locks at regular
> intervals. Maybe once every 10 seconds or so.

Sure, that's a known problem. And now that we have timed
events the rescan should be easy to implement.

BTW, the current discussion for the Linux kernel about a
general async syscall interface, does that also cover fcntl
locks? Just curious.

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