nfsd: use threads array as-is in netlink interface

The old nfsdfs interface for starting a server with multiple pools
handles the special case of a single entry array passed down from
userland by distributing the threads over every NUMA node.

The netlink control interface however constructs an array of length
nfsd_nrpools() and fills any unprovided slots with 0's. This behavior
defeats the special casing that the old interface relies on.

Change nfsd_nl_threads_set_doit() to pass down the array from userland
as-is.

Fixes: 7f5c330b2620 ("nfsd: allow passing in array of thread counts via netlink")
Cc: [e-mail]
Reported-by: Mike Snitzer <[e-mail]>
Closes: https://lore.kernel.org/linux-nfs/[e-mail]/
Signed-off-by: Jeff Layton <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Tested-by: Mike Snitzer <[e-mail]>
Signed-off-by: Chuck Lever <[e-mail]>

fs/nfsd/nfsctl.c

···
  */
 int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
 {
-	int *nthreads, count = 0, nrpools, i, ret = -EOPNOTSUPP, rem;
+	int *nthreads, nrpools = 0, i, ret = -EOPNOTSUPP, rem;
 	struct net *net = genl_info_net(info);
 	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
 	const struct nlattr *attr;
···
 	/* count number of SERVER_THREADS values */
 	nlmsg_for_each_attr(attr, info->nlhdr, GENL_HDRLEN, rem) {
 		if (nla_type(attr) == NFSD_A_SERVER_THREADS)
-			count++;
+			nrpools++;
 	}
 
 	mutex_lock(&nfsd_mutex);
 
-	nrpools = max(count, nfsd_nrpools(net));
 	nthreads = kcalloc(nrpools, sizeof(int), GFP_KERNEL);
 	if (!nthreads) {
 		ret = -ENOMEM;