A future patch will remove refcounting on svc_serv as it is of little
use.
It is currently used to keep the svc around while the pool_stats file is
open.
Change this to get the pointer, protected by the mutex, only in
seq_start, and the release the mutex in seq_stop.
This means that if the nfsd server is stopped and restarted while the
pool_stats file it open, then some pool stats info could be from the
first instance and some from the second. This might appear odd, but is
unlikely to be a problem in practice.
Signed-off-by: NeilBrown <neilb@xxxxxxx>
---
fs/nfsd/nfsctl.c | 2 +-
fs/nfsd/nfssvc.c | 30 ++++++++---------------
include/linux/sunrpc/svc.h | 5 +++-
net/sunrpc/svc_xprt.c | 49 ++++++++++++++++++++++++++++++++------
4 files changed, 57 insertions(+), 29 deletions(-)
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 79efb1075f38..d78ae4452946 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -179,7 +179,7 @@ static const struct file_operations pool_stats_operations = {
.open = nfsd_pool_stats_open,
.read = seq_read,
.llseek = seq_lseek,
- .release = nfsd_pool_stats_release,
+ .release = svc_pool_stats_release,
};
DEFINE_SHOW_ATTRIBUTE(nfsd_reply_cache_stats);
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 6c968c02cc29..203e1cfc1cad 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -1072,30 +1072,20 @@ bool nfssvc_encode_voidres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
return true;
}
-int nfsd_pool_stats_open(struct inode *inode, struct file *file)
+static struct svc_serv *nfsd_get_serv(struct seq_file *s, bool start)
{
- int ret;
- struct nfsd_net *nn = net_generic(inode->i_sb->s_fs_info, nfsd_net_id);
-
- mutex_lock(&nfsd_mutex);
- if (nn->nfsd_serv == NULL) {
+ struct nfsd_net *nn = net_generic(file_inode(s->file)->i_sb->s_fs_info,
+ nfsd_net_id);
+ if (start) {
+ mutex_lock(&nfsd_mutex);
+ return nn->nfsd_serv;
+ } else {
mutex_unlock(&nfsd_mutex);
- return -ENODEV;
+ return NULL;
}
- svc_get(nn->nfsd_serv);
- ret = svc_pool_stats_open(nn->nfsd_serv, file);
- mutex_unlock(&nfsd_mutex);
- return ret;
}
-int nfsd_pool_stats_release(struct inode *inode, struct file *file)
+int nfsd_pool_stats_open(struct inode *inode, struct file *file)
{
- struct seq_file *seq = file->private_data;
- struct svc_serv *serv = seq->private;
- int ret = seq_release(inode, file);
-
- mutex_lock(&nfsd_mutex);
- svc_put(serv);
- mutex_unlock(&nfsd_mutex);
- return ret;
+ return svc_pool_stats_open(nfsd_get_serv, file);
}
diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index b10f987509cc..11acad6988a2 100644
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -433,7 +433,10 @@ void svc_exit_thread(struct svc_rqst *);
struct svc_serv * svc_create_pooled(struct svc_program *, unsigned int,
int (*threadfn)(void *data));
int svc_set_num_threads(struct svc_serv *, struct svc_pool *, int);
-int svc_pool_stats_open(struct svc_serv *serv, struct file *file);
+int svc_pool_stats_open(struct svc_serv *(*get_serv)(struct seq_file *, bool),
+ struct file *file);
+int svc_pool_stats_release(struct inode *inode,
+ struct file *file);
void svc_process(struct svc_rqst *rqstp);
void svc_process_bc(struct rpc_rqst *req, struct svc_rqst *rqstp);
int svc_register(const struct svc_serv *, struct net *, const int,
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index fee83d1024bc..2f99f7475b7b 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -1366,26 +1366,38 @@ EXPORT_SYMBOL_GPL(svc_xprt_names);
/*----------------------------------------------------------------------------*/
+struct pool_private {
+ struct svc_serv *(*get_serv)(struct seq_file *, bool);
+ struct svc_serv *serv;
+};
+
static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
{
unsigned int pidx = (unsigned int)*pos;
- struct svc_serv *serv = m->private;
+ struct pool_private *pp = m->private;
dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
+ pp->serv = pp->get_serv(m, true);
+
if (!pidx)
return SEQ_START_TOKEN;
- return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]);
+ if (!pp->serv)
+ return NULL;
+ return (pidx > pp->serv->sv_nrpools ? NULL : &pp->serv->sv_pools[pidx-1]);
}
static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos)
{
struct svc_pool *pool = p;
- struct svc_serv *serv = m->private;
+ struct pool_private *pp = m->private;
+ struct svc_serv *serv = pp->serv;
dprintk("svc_pool_stats_next, *pos=%llu\n", *pos);
- if (p == SEQ_START_TOKEN) {
+ if (!serv) {
+ pool = NULL;
+ } else if (p == SEQ_START_TOKEN) {
pool = &serv->sv_pools[0];
} else {
unsigned int pidx = (pool - &serv->sv_pools[0]);
@@ -1400,6 +1412,9 @@ static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos)
static void svc_pool_stats_stop(struct seq_file *m, void *p)
{
+ struct pool_private *pp = m->private;
+
+ pp->get_serv(m, false);
}
static int svc_pool_stats_show(struct seq_file *m, void *p)
@@ -1427,15 +1442,35 @@ static const struct seq_operations svc_pool_stats_seq_ops = {
.show = svc_pool_stats_show,
};
-int svc_pool_stats_open(struct svc_serv *serv, struct file *file)
+int svc_pool_stats_open(struct svc_serv *(*get_serv)(struct seq_file *, bool),
+ struct file *file)
{
+ struct pool_private *pp;
int err;
+ pp = kmalloc(sizeof(*pp), GFP_KERNEL);
+ if (!pp)
+ return -ENOMEM;
+
err = seq_open(file, &svc_pool_stats_seq_ops);
- if (!err)
- ((struct seq_file *) file->private_data)->private = serv;
+ if (!err) {
+ pp->get_serv = get_serv;
+ ((struct seq_file *) file->private_data)->private = pp;
+ } else
+ kfree(pp);
+
return err;
}
EXPORT_SYMBOL(svc_pool_stats_open);
+int svc_pool_stats_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *seq = file->private_data;
+
+ kfree(seq->private);
+ seq->private = NULL;
+ return seq_release(inode, file);
+}
+EXPORT_SYMBOL(svc_pool_stats_release);
+
/*----------------------------------------------------------------------------*/
--
2.42.0
