On Apr 28, 2015, at 4:21 PM, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > Currently the client will just crap out if a CB_NULL comes in at the > same time as a slot controlled CB_COMPOUND that includes a CB_SEQUENCE. Under what circumstances does the server send a CB_NULL while a CB_COMPOUND is in flight? > I don't really understand how the spec wants to treat CB_NULL in > relation to the available backchannel slots, but given that it's > not part of the sequences in CB_SEQUENCE it somehow nees to bypass them. > > If we make sure to overallocate the rpc-level buffers so that we > have more than the available NFS-level slots we should be safe from > this condition which makes a 4.1 server doing heavy recalls under > load very unhapy by not returning an NFS level reply to its layout > recalls. > > I dont really like this patch much, so any idea for a better solution > would be highly welcome! > > diff --git a/fs/nfs/callback.h b/fs/nfs/callback.h > index 84326e9..7afb3ef 100644 > --- a/fs/nfs/callback.h > +++ b/fs/nfs/callback.h > @@ -205,7 +205,7 @@ extern int nfs4_set_callback_sessionid(struct nfs_client *clp); > * so we limit their concurrency to 1 by setting up the maximum number > * of slots for the backchannel. > */ > -#define NFS41_BC_MIN_CALLBACKS 1 > +#define NFS41_BC_MIN_CALLBACKS 2 > #define NFS41_BC_MAX_CALLBACKS 1 > > extern unsigned int nfs_callback_set_tcpport; > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever chuck[dot]lever[at]oracle[dot]com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
