Sorry, every cacheable request holds a ref on its DRC as well as its
DUPREQ. The ref on DUPREQ should be released when the request goes away
(via nfs_dupreq_rele). The ref on DRC will be released when the
corresponding DUPREQ request gets released. Since we release DUPREQs while
processing other requests, you are right that the DRC won't be freed if
there are no more requests that would use the same DRC.
I think we should be freeing dupreq periodically using a timed function,
something like that drc_free_expired.
Regards, Malahal.
On Tue, May 2, 2017 at 10:38 AM, Satya Prakash GS <g.satyaprak...@gmail.com>
wrote:
> > On Tue, May 2, 2017 at 7:58 AM, Malahal Naineni <mala...@gmail.com>
> wrote:
> > A dupreq will place a refcount on its DRC when it calls xxx_get_drc, so
> we
> > will release that DRC refcount when we free the dupreq.
>
> Ok, so every dupreq holds a ref on the drc. In case of drc cache hit,
> a dupreq entry can ref the
> drc more than once. This is still fine because unless the dupreq entry
> ref goes to zero the drc isn't freed.
>
> > nfs_dupreq_finish() shouldn't free its own dupreq. When it does free some
> > other dupreq, we will release DRC refcount corresponding to that dupreq.
>
> > When we free all dupreqs that belong to a DRC
>
> In the case of a disconnected client when are all the dupreqs freed ?
>
> When all the filesystem operations subside from a client (mount point
> is no longer in use),
> nfs_dupreq_finish doesn't get called anymore. This is the only place
> where dupreq entries are removed from
> the drc. If the entries aren't removed from drc, drc refcnt doesn't go to
> 0.
>
> >, its refcount should go to
> > zero (maybe another ref is held by the socket itself, so the socket has
> to
> > be closed as well).
> >
> >
> > In fact, if we release DRC refcount without freeing the dupreq, that
> would
> > be a bug!
> >
> > Regards, Malahal.
> >
> Thanks,
> Satya.
>
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