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Subject[PATCH 011 of 11] knfsd: allow admin to set nthreads per node

From: Greg Banks <gnb@melbourne.sgi.com>

knfsd: Add /proc/fs/nfsd/pool_threads which allows the sysadmin (or
a userspace daemon) to read and change the number of nfsd threads
in each pool. The format is a list of space-separated integers,
one per pool.

Signed-off-by: Greg Banks <gnb@melbourne.sgi.com>
Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./fs/nfsd/nfsctl.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++
./fs/nfsd/nfssvc.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 144 insertions(+)
diff .prev/fs/nfsd/nfsctl.c ./fs/nfsd/nfsctl.c
--- .prev/fs/nfsd/nfsctl.c 2006-07-31 10:29:37.000000000 +1000
+++ ./fs/nfsd/nfsctl.c 2006-07-31 10:31:46.000000000 +1000
@@ -54,6 +54,7 @@ enum {
NFSD_List,
NFSD_Fh,
NFSD_Threads,
+ NFSD_Pool_Threads,
NFSD_Versions,
NFSD_Ports,
/*
@@ -78,6 +79,7 @@ static ssize_t write_getfd(struct file *
static ssize_t write_getfs(struct file *file, char *buf, size_t size);
static ssize_t write_filehandle(struct file *file, char *buf, size_t size);
static ssize_t write_threads(struct file *file, char *buf, size_t size);
+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);
#ifdef CONFIG_NFSD_V4
@@ -95,6 +97,7 @@ static ssize_t (*write_op[])(struct file
[NFSD_Getfs] = write_getfs,
[NFSD_Fh] = write_filehandle,
[NFSD_Threads] = write_threads,
+ [NFSD_Pool_Threads] = write_pool_threads,
[NFSD_Versions] = write_versions,
[NFSD_Ports] = write_ports,
#ifdef CONFIG_NFSD_V4
@@ -363,6 +366,72 @@ static ssize_t write_threads(struct file
return strlen(buf);
}

+extern int nfsd_nrpools(void);
+extern int nfsd_get_nrthreads(int n, int *);
+extern int nfsd_set_nrthreads(int n, int *);
+
+static ssize_t write_pool_threads(struct file *file, char *buf, size_t size)
+{
+ /* if size > 0, look for an array of number of threads per node
+ * and apply them then write out number of threads per node as reply
+ */
+ char *mesg = buf;
+ int i;
+ int rv;
+ int len;
+ int npools = nfsd_nrpools();
+ int *nthreads;
+
+ if (npools == 0) {
+ /*
+ * NFS is shut down. The admin can start it by
+ * writing to the threads file but NOT the pool_threads
+ * file, sorry. Report zero threads.
+ */
+ strcpy(buf, "0\n");
+ return strlen(buf);
+ }
+
+ nthreads = kcalloc(npools, sizeof(int), GFP_KERNEL);
+ if (nthreads == NULL)
+ return -ENOMEM;
+
+ if (size > 0) {
+ for (i = 0 ; i < npools ; i++) {
+ rv = get_int(&mesg, &nthreads[i]);
+ if (rv == -ENOENT)
+ break; /* fewer numbers than pools */
+ if (rv)
+ goto out_free; /* syntax error */
+ rv = -EINVAL;
+ if (nthreads[i] < 0)
+ goto out_free;
+ }
+ rv = nfsd_set_nrthreads(i, nthreads);
+ if (rv)
+ goto out_free;
+ }
+
+ rv = nfsd_get_nrthreads(npools, nthreads);
+ if (rv)
+ goto out_free;
+
+ mesg = buf;
+ size = SIMPLE_TRANSACTION_LIMIT;
+ for (i = 0 ; i < npools && size > 0 ; i++) {
+ snprintf(mesg, size, "%d%c", nthreads[i], (i == npools-1 ? '\n' : ' '));
+ len = strlen(mesg);
+ size -= len;
+ mesg += len;
+ }
+
+ return (mesg-buf);
+
+out_free:
+ kfree(nthreads);
+ return rv;
+}
+
static ssize_t write_versions(struct file *file, char *buf, size_t size)
{
/*
@@ -544,6 +613,7 @@ static int nfsd_fill_super(struct super_
[NFSD_List] = {"exports", &exports_operations, S_IRUGO},
[NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR},
[NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
+ [NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR},
[NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR},
[NFSD_Ports] = {"portlist", &transaction_ops, S_IWUSR|S_IRUGO},
#ifdef CONFIG_NFSD_V4
diff .prev/fs/nfsd/nfssvc.c ./fs/nfsd/nfssvc.c
--- .prev/fs/nfsd/nfssvc.c 2006-07-31 10:31:08.000000000 +1000
+++ ./fs/nfsd/nfssvc.c 2006-07-31 10:31:46.000000000 +1000
@@ -238,6 +238,80 @@ static int nfsd_init_socks(int port)
return 0;
}

+int nfsd_nrpools(void)
+{
+ if (nfsd_serv == NULL)
+ return 0;
+ else
+ return nfsd_serv->sv_nrpools;
+}
+
+int nfsd_get_nrthreads(int n, int *nthreads)
+{
+ int i = 0;
+
+ if (nfsd_serv != NULL) {
+ for (i = 0 ; i < nfsd_serv->sv_nrpools && i < n ; i++)
+ nthreads[i] = nfsd_serv->sv_pools[i].sp_nrthreads;
+ }
+
+ return 0;
+}
+
+int nfsd_set_nrthreads(int n, int *nthreads)
+{
+ int i = 0;
+ int tot = 0;
+ int err = 0;
+
+ if (nfsd_serv == NULL || n <= 0)
+ return 0;
+
+ if (n > nfsd_serv->sv_nrpools)
+ n = nfsd_serv->sv_nrpools;
+
+ /* enforce a global maximum number of threads */
+ tot = 0;
+ for (i = 0 ; i < n ; i++) {
+ if (nthreads[i] > NFSD_MAXSERVS)
+ nthreads[i] = NFSD_MAXSERVS;
+ tot += nthreads[i];
+ }
+ if (tot > NFSD_MAXSERVS) {
+ /* total too large: scale down requested numbers */
+ for (i = 0 ; i < n && tot > 0 ; i++) {
+ int new = nthreads[i] * NFSD_MAXSERVS / tot;
+ tot -= (nthreads[i] - new);
+ nthreads[i] = new;
+ }
+ for (i = 0 ; i < n && tot > 0 ; i++) {
+ nthreads[i]--;
+ tot--;
+ }
+ }
+
+ /*
+ * There must always be a thread in pool 0; the admin
+ * can't shut down NFS completely using pool_threads.
+ */
+ if (nthreads[0] == 0)
+ nthreads[0] = 1;
+
+ /* apply the new numbers */
+ lock_kernel();
+ svc_get(nfsd_serv);
+ for (i = 0 ; i < n ; i++) {
+ err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
+ nthreads[i]);
+ if (err)
+ break;
+ }
+ svc_destroy(nfsd_serv);
+ unlock_kernel();
+
+ return err;
+}
+
int
nfsd_svc(unsigned short port, int nrservs)
{
-
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