Re: Still seeing hangs in xlog_grant_log_space

[Ben Myers <bpm@xxxxxxx>]

On Fri, Jun 08, 2012 at 10:28:26AM +1000, Dave Chinner wrote:
...
> And because the inodes pin the tail of the AIL, there's not enough
> space in the log for the xfs_sync_worker to trigger a log force via
> the dummy transaction, and hence we deadlock.
>
> FWIW, there's an argument that can be made here for an unconditional
> log force in xfs_sync_worker() to provide a "get out gaol free" card
> here. 

No kidding!
http://oss.sgi.com/archives/xfs/2012-05/msg00312.html

> The thing is, I would prefer that the filesystems hang so that
> we find out about these issues and have to understand them and fix
> them. IMO, there is nothing harder to detect and debug than short
> duration, temporary stalls of the filesystem...

I agree.. such a patch is not for general consumption.  We want to fix the
actual problem, not work around it with a prod on a timer.  ;)

Regards,
        Ben