[Gluster-devel] Spurious termination of fuse invalidation notifier thread

[Raghavendra Gowdappa]

----- Original Message -----
> From: "Xavier Hernandez" <xhernandez at datalab.es>
> To: "Raghavendra Gowdappa" <rgowdapp at redhat.com>, "Kaleb Keithley" <kkeithle at redhat.com>, "Pranith Kumar Karampuri"
> <pkarampu at redhat.com>
> Cc: "Csaba Henk" <chenk at redhat.com>, "Gluster Devel" <gluster-devel at gluster.org>
> Sent: Monday, September 5, 2016 12:46:43 PM
> Subject: Re: Spurious termination of fuse invalidation notifier thread
> 
> Hi Raghavendra,
> 
> On 03/09/16 05:42, Raghavendra Gowdappa wrote:
> > Hi Xavi/Kaleb/Pranith,
> >
> > During few of our older conversations (like [1], but not only one), some of
> > you had reported that the thread which writes invalidation notifications
> > (of inodes, entries) to /dev/fuse terminates spuriously. Csaba tried to
> > reproduce the issue, but without success. It would be helpful if you
> > provide any information on reproducer and/or possible reasons for the
> > behavior.
> 
> I didn't found what really caused the problem. I only saw the
> termination message on a production server after some days working but
> hadn't had the opportunity to debug it.
> 
> Looking at the code, the only conclusion I got is that the result from
> the write to /dev/fuse was unexpected. The patch solves this and I
> haven't seen the problem again.
> 
> The old code only manages ENOENT error. It exits the thread for any
> other error. I guess that in some situations a write to /dev/fuse can
> return other "non fatal" errors.

Thanks Xavi. Now I remember the changes. Since you have not seen spurious termination after the changes, I assume the issue is fixed.

> 
> As a guess, I think it may be a failure in an entry invalidation.
> Looking at the code of fuse, it may return ENOTDIR if parent of the
> entry is not a directory and some race happens doing rm/create while
> sending invalidations in the background. Another possibility is
> ENOTEMPTY if the entry references a non empty directory (again probably
> caused by races between user mode operations and background
> invalidations). Anyway this is only a guess, I have no more information.
> 
> Xavi
> 
> >
> > [1]
> > http://review.gluster.org/#/c/13274/1/xlators/mount/fuse/src/fuse-bridge.c
> >
> > regards,
> > Raghavendra
> >
>