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Message-Id: <20260106-nfsd-dynathread-v2-8-416e5f27b2b6@kernel.org>
Date: Tue, 06 Jan 2026 13:59:50 -0500
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>, NeilBrown <neil@...wn.name>,
Olga Kornievskaia <okorniev@...hat.com>, Dai Ngo <Dai.Ngo@...cle.com>,
Tom Talpey <tom@...pey.com>, Trond Myklebust <trondmy@...nel.org>,
Anna Schumaker <anna@...nel.org>
Cc: linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v2 8/8] nfsd: add controls to set the minimum number of
threads per pool
Add a new "min_threads" variable to the nfsd_net, along with the
corresponding nfsdfs and netlink interfaces to set that value from
userland. Pass that value to svc_set_pool_threads() and
svc_set_num_threads().
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
Documentation/netlink/specs/nfsd.yaml | 5 ++++
fs/nfsd/netlink.c | 5 ++--
fs/nfsd/netns.h | 6 +++++
fs/nfsd/nfsctl.c | 50 +++++++++++++++++++++++++++++++++++
fs/nfsd/nfssvc.c | 4 +--
fs/nfsd/trace.h | 19 +++++++++++++
include/uapi/linux/nfsd_netlink.h | 1 +
7 files changed, 86 insertions(+), 4 deletions(-)
diff --git a/Documentation/netlink/specs/nfsd.yaml b/Documentation/netlink/specs/nfsd.yaml
index 100363029e82aed87295e34a008ab771a95d508c..badb2fe57c9859c6932c621a589da694782b0272 100644
--- a/Documentation/netlink/specs/nfsd.yaml
+++ b/Documentation/netlink/specs/nfsd.yaml
@@ -78,6 +78,9 @@ attribute-sets:
-
name: scope
type: string
+ -
+ name: min-threads
+ type: u32
-
name: version
attributes:
@@ -159,6 +162,7 @@ operations:
- gracetime
- leasetime
- scope
+ - min-threads
-
name: threads-get
doc: get the number of running threads
@@ -170,6 +174,7 @@ operations:
- gracetime
- leasetime
- scope
+ - min-threads
-
name: version-set
doc: set nfs enabled versions
diff --git a/fs/nfsd/netlink.c b/fs/nfsd/netlink.c
index ac51a44e1065ec3f1d88165f70a831a828b58394..887525964451e640304371e33aa4f415b4ff2848 100644
--- a/fs/nfsd/netlink.c
+++ b/fs/nfsd/netlink.c
@@ -24,11 +24,12 @@ const struct nla_policy nfsd_version_nl_policy[NFSD_A_VERSION_ENABLED + 1] = {
};
/* NFSD_CMD_THREADS_SET - do */
-static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_SCOPE + 1] = {
+static const struct nla_policy nfsd_threads_set_nl_policy[NFSD_A_SERVER_MIN_THREADS + 1] = {
[NFSD_A_SERVER_THREADS] = { .type = NLA_U32, },
[NFSD_A_SERVER_GRACETIME] = { .type = NLA_U32, },
[NFSD_A_SERVER_LEASETIME] = { .type = NLA_U32, },
[NFSD_A_SERVER_SCOPE] = { .type = NLA_NUL_STRING, },
+ [NFSD_A_SERVER_MIN_THREADS] = { .type = NLA_U32, },
};
/* NFSD_CMD_VERSION_SET - do */
@@ -57,7 +58,7 @@ static const struct genl_split_ops nfsd_nl_ops[] = {
.cmd = NFSD_CMD_THREADS_SET,
.doit = nfsd_nl_threads_set_doit,
.policy = nfsd_threads_set_nl_policy,
- .maxattr = NFSD_A_SERVER_SCOPE,
+ .maxattr = NFSD_A_SERVER_MIN_THREADS,
.flags = GENL_ADMIN_PERM | GENL_CMD_CAP_DO,
},
{
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index fe8338735e7cc599a2b6aebbea3ec3e71b07f636..5bde7975c343798639fec54e7daa80fc9ce060d9 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -130,6 +130,12 @@ struct nfsd_net {
seqlock_t writeverf_lock;
unsigned char writeverf[8];
+ /*
+ * Minimum number of threads to run per pool. If 0 then the
+ * min == max requested number of threads.
+ */
+ unsigned int min_threads;
+
u32 clientid_base;
u32 clientid_counter;
u32 clverifier_counter;
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 084fc517e9e160b56cba0c40ac0daa749be3ffcd..035f08a31607b631ebfe2beda2c5e30781daaa26 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -48,6 +48,7 @@ enum {
NFSD_Versions,
NFSD_Ports,
NFSD_MaxBlkSize,
+ NFSD_MinThreads,
NFSD_Filecache,
NFSD_Leasetime,
NFSD_Gracetime,
@@ -67,6 +68,7 @@ static ssize_t write_pool_threads(struct file *file, char *buf, size_t size);
static ssize_t write_versions(struct file *file, char *buf, size_t size);
static ssize_t write_ports(struct file *file, char *buf, size_t size);
static ssize_t write_maxblksize(struct file *file, char *buf, size_t size);
+static ssize_t write_minthreads(struct file *file, char *buf, size_t size);
#ifdef CONFIG_NFSD_V4
static ssize_t write_leasetime(struct file *file, char *buf, size_t size);
static ssize_t write_gracetime(struct file *file, char *buf, size_t size);
@@ -85,6 +87,7 @@ static ssize_t (*const write_op[])(struct file *, char *, size_t) = {
[NFSD_Versions] = write_versions,
[NFSD_Ports] = write_ports,
[NFSD_MaxBlkSize] = write_maxblksize,
+ [NFSD_MinThreads] = write_minthreads,
#ifdef CONFIG_NFSD_V4
[NFSD_Leasetime] = write_leasetime,
[NFSD_Gracetime] = write_gracetime,
@@ -906,6 +909,46 @@ static ssize_t write_maxblksize(struct file *file, char *buf, size_t size)
nfsd_max_blksize);
}
+/*
+ * write_minthreads - Set or report the current min number of threads per pool
+ *
+ * Input:
+ * buf: ignored
+ * size: zero
+ * OR
+ *
+ * Input:
+ * buf: C string containing an unsigned
+ * integer value representing the new
+ * min number of threads per pool
+ * size: non-zero length of C string in @buf
+ * Output:
+ * On success: passed-in buffer filled with '\n'-terminated C string
+ * containing numeric value of min_threads setting
+ * for this net namespace;
+ * return code is the size in bytes of the string
+ * On error: return code is zero or a negative errno value
+ */
+static ssize_t write_minthreads(struct file *file, char *buf, size_t size)
+{
+ char *mesg = buf;
+ struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
+ unsigned int minthreads = nn->min_threads;
+
+ if (size > 0) {
+ int rv = get_uint(&mesg, &minthreads);
+
+ if (rv)
+ return rv;
+ trace_nfsd_ctl_minthreads(netns(file), minthreads);
+ mutex_lock(&nfsd_mutex);
+ nn->min_threads = minthreads;
+ mutex_unlock(&nfsd_mutex);
+ }
+
+ return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%u\n", minthreads);
+}
+
#ifdef CONFIG_NFSD_V4
static ssize_t __nfsd4_write_time(struct file *file, char *buf, size_t size,
time64_t *time, struct nfsd_net *nn)
@@ -1298,6 +1341,7 @@ static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc)
[NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR},
[NFSD_Ports] = {"portlist", &transaction_ops, S_IWUSR|S_IRUGO},
[NFSD_MaxBlkSize] = {"max_block_size", &transaction_ops, S_IWUSR|S_IRUGO},
+ [NFSD_MinThreads] = {"min_threads", &transaction_ops, S_IWUSR|S_IRUGO},
[NFSD_Filecache] = {"filecache", &nfsd_file_cache_stats_fops, S_IRUGO},
#ifdef CONFIG_NFSD_V4
[NFSD_Leasetime] = {"nfsv4leasetime", &transaction_ops, S_IWUSR|S_IRUSR},
@@ -1642,6 +1686,10 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
scope = nla_data(attr);
}
+ attr = info->attrs[NFSD_A_SERVER_MIN_THREADS];
+ if (attr)
+ nn->min_threads = nla_get_u32(attr);
+
ret = nfsd_svc(nrpools, nthreads, net, get_current_cred(), scope);
if (ret > 0)
ret = 0;
@@ -1681,6 +1729,8 @@ int nfsd_nl_threads_get_doit(struct sk_buff *skb, struct genl_info *info)
nn->nfsd4_grace) ||
nla_put_u32(skb, NFSD_A_SERVER_LEASETIME,
nn->nfsd4_lease) ||
+ nla_put_u32(skb, NFSD_A_SERVER_MIN_THREADS,
+ nn->min_threads) ||
nla_put_string(skb, NFSD_A_SERVER_SCOPE,
nn->nfsd_name);
if (err)
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 55a4caaea97633670ffea1144ce4ac810b82c2ab..6bf3044934a0ab077a1af791860e7fa0faff71f1 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -690,7 +690,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
/* Special case: When n == 1, distribute threads equally among pools. */
if (n == 1)
- return svc_set_num_threads(nn->nfsd_serv, 0, nthreads[0]);
+ return svc_set_num_threads(nn->nfsd_serv, nn->min_threads, nthreads[0]);
if (n > nn->nfsd_serv->sv_nrpools)
n = nn->nfsd_serv->sv_nrpools;
@@ -718,7 +718,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
for (i = 0; i < n; i++) {
err = svc_set_pool_threads(nn->nfsd_serv,
&nn->nfsd_serv->sv_pools[i],
- 0, nthreads[i]);
+ nn->min_threads, nthreads[i]);
if (err)
goto out;
}
diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h
index 8885fd9bead98ebf55379d68ab9c3701981a5150..d1d0b0dd054588a8c20e3386356dfa4e9632b8e0 100644
--- a/fs/nfsd/trace.h
+++ b/fs/nfsd/trace.h
@@ -2164,6 +2164,25 @@ TRACE_EVENT(nfsd_ctl_maxblksize,
)
);
+TRACE_EVENT(nfsd_ctl_minthreads,
+ TP_PROTO(
+ const struct net *net,
+ int minthreads
+ ),
+ TP_ARGS(net, minthreads),
+ TP_STRUCT__entry(
+ __field(unsigned int, netns_ino)
+ __field(int, minthreads)
+ ),
+ TP_fast_assign(
+ __entry->netns_ino = net->ns.inum;
+ __entry->minthreads = minthreads
+ ),
+ TP_printk("minthreads=%d",
+ __entry->minthreads
+ )
+);
+
TRACE_EVENT(nfsd_ctl_time,
TP_PROTO(
const struct net *net,
diff --git a/include/uapi/linux/nfsd_netlink.h b/include/uapi/linux/nfsd_netlink.h
index e157e2009ea8c1ef805301261d536c82677821ef..e9efbc9e63d83ed25fcd790b7a877c0023638f15 100644
--- a/include/uapi/linux/nfsd_netlink.h
+++ b/include/uapi/linux/nfsd_netlink.h
@@ -35,6 +35,7 @@ enum {
NFSD_A_SERVER_GRACETIME,
NFSD_A_SERVER_LEASETIME,
NFSD_A_SERVER_SCOPE,
+ NFSD_A_SERVER_MIN_THREADS,
__NFSD_A_SERVER_MAX,
NFSD_A_SERVER_MAX = (__NFSD_A_SERVER_MAX - 1)
--
2.52.0
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