nfsd: use threads array as-is in netlink interface

JIRA: https://issues.redhat.com/browse/RHEL-96874
Upstream-Status: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next

commit 8ea688a
Author: Jeff Layton <jlayton@kernel.org>
Date: Tue, 27 May 2025 20:12:47 -0400

    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: 7f5c330 ("nfsd: allow passing in array of thread counts via netlink")
    Cc: stable@vger.kernel.org
    Reported-by: Mike Snitzer <snitzer@kernel.org>
    Closes: https://lore.kernel.org/linux-nfs/aDC-ftnzhJAlwqwh@kernel.org/
    Signed-off-by: Jeff Layton <jlayton@kernel.org>
    Reviewed-by: Simon Horman <horms@kernel.org>
    Tested-by: Mike Snitzer <snitzer@kernel.org>
    Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>

Author: bcodding-rh

fs/nfsd/nfsctl.c

@@ -1653,7 +1653,7 @@ int nfsd_nl_rpc_status_get_dumpit(struct sk_buff *skb,
  */
 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;
@@ -1665,12 +1665,11 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
 	/* 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;