unimore/kernel-hacking-2024-linux-steffo
unimore/kernel-hacking-2024-linux-steffo
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nfsd: make nfsd_svc take an array of thread counts

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Now that the refcounting is fixed, rework nfsd_svc to use the same
thread setup as the pool_threads interface. Have it take an array of
thread counts instead of just a single value, and pass that from the
netlink threads set interface.  Since the new netlink interface doesn't
have the same restriction as pool_threads, move the guard against
shutting down all threads to write_pool_threads.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Jeff Layton 2024-06-13 14:34:31 -04:00 committed by Chuck Lever
parent 8e0c8d2395
commit b4d8f22891
3 changed files with 45 additions and 24 deletions
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12
fs/nfsd/nfsctl.c
View file

@ -406,7 +406,7 @@ static ssize_t write_threads(struct file *file, char *buf, size_t size)
return -EINVAL;
trace_nfsd_ctl_threads(net, newthreads);
mutex_lock(&nfsd_mutex);
rv = nfsd_svc(newthreads, net, file->f_cred, NULL);
rv = nfsd_svc(1, &newthreads, net, file->f_cred, NULL);
mutex_unlock(&nfsd_mutex);
if (rv < 0)
return rv;
@ -481,6 +481,14 @@ static ssize_t write_pool_threads(struct file *file, char *buf, size_t size)
goto out_free;
trace_nfsd_ctl_pool_threads(net, i, nthreads[i]);
}
/*
* 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;
rv = nfsd_set_nrthreads(i, nthreads, net);
if (rv)
goto out_free;
@ -1696,7 +1704,7 @@ int nfsd_nl_threads_set_doit(struct sk_buff *skb, struct genl_info *info)
scope = nla_data(attr);
}
ret = nfsd_svc(nthreads, net, get_current_cred(), scope);
ret = nfsd_svc(1, &nthreads, net, get_current_cred(), scope);
out_unlock:
mutex_unlock(&nfsd_mutex);

3
fs/nfsd/nfsd.h
View file

@ -103,7 +103,8 @@ bool nfssvc_encode_voidres(struct svc_rqst *rqstp,
/*
* Function prototypes.
*/
int nfsd_svc(int nrservs, struct net *net, const struct cred *cred, const char *scope);
int nfsd_svc(int n, int *nservers, struct net *net,
const struct cred *cred, const char *scope);
int nfsd_dispatch(struct svc_rqst *rqstp);
int nfsd_nrthreads(struct net *);

54
fs/nfsd/nfssvc.c
View file

@ -709,6 +709,19 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
return 0;
}
/**
* nfsd_set_nrthreads - set the number of running threads in the net's service
* @n: number of array members in @nthreads
* @nthreads: array of thread counts for each pool
* @net: network namespace to operate within
*
* This function alters the number of running threads for the given network
* namespace in each pool. If passed an array longer then the number of pools
* the extra pool settings are ignored. If passed an array shorter than the
* number of pools, the missing values are interpreted as 0's.
*
* Returns 0 on success or a negative errno on error.
*/
int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
{
int i = 0;
@ -716,11 +729,18 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
int err = 0;
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
WARN_ON(!mutex_is_locked(&nfsd_mutex));
lockdep_assert_held(&nfsd_mutex);
if (nn->nfsd_serv == NULL || n <= 0)
return 0;
/*
* Special case: When n == 1, pass in NULL for the pool, so that the
* change is distributed equally among them.
*/
if (n == 1)
return svc_set_num_threads(nn->nfsd_serv, NULL, nthreads[0]);
if (n > nn->nfsd_serv->sv_nrpools)
n = nn->nfsd_serv->sv_nrpools;
@ -743,13 +763,6 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
}
}
/*
* 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 */
for (i = 0; i < n; i++) {
err = svc_set_num_threads(nn->nfsd_serv,
@ -761,13 +774,19 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
return err;
}
/*
* Adjust the number of threads and return the new number of threads.
* This is also the function that starts the server if necessary, if
* this is the first time nrservs is nonzero.
/**
* nfsd_svc: start up or shut down the nfsd server
* @n: number of array members in @nthreads
* @nthreads: array of thread counts for each pool
* @net: network namespace to operate within
* @cred: credentials to use for xprt creation
* @scope: server scope value (defaults to nodename)
*
* Adjust the number of threads in each pool and return the new
* total number of threads in the service.
*/
int
nfsd_svc(int nrservs, struct net *net, const struct cred *cred, const char *scope)
nfsd_svc(int n, int *nthreads, struct net *net, const struct cred *cred, const char *scope)
{
int error;
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
@ -777,13 +796,6 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred, const char *scop
dprintk("nfsd: creating service\n");
nrservs = max(nrservs, 0);
nrservs = min(nrservs, NFSD_MAXSERVS);
error = 0;
if (nrservs == 0 && nn->nfsd_serv == NULL)
goto out;
strscpy(nn->nfsd_name, scope ? scope : utsname()->nodename,
sizeof(nn->nfsd_name));
@ -795,7 +807,7 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred, const char *scop
error = nfsd_startup_net(net, cred);
if (error)
goto out_put;
error = svc_set_num_threads(serv, NULL, nrservs);
error = nfsd_set_nrthreads(n, nthreads, net);
if (error)
goto out_put;
error = serv->sv_nrthreads;