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/netns.h | 4 +++- fs/nfsd/nfsctl.c | 2 +- fs/nfsd/nfssvc.c | 24 ++---------------------- include/linux/sunrpc/svc.h | 8 +++++++- net/sunrpc/svc_xprt.c | 32 +++++++++++++++++++++++--------- 5 files changed, 36 insertions(+), 34 deletions(-) diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index ab303a8b77d5..16dbef245dbb 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -123,7 +123,9 @@ struct nfsd_net { u32 clientid_counter; u32 clverifier_counter; - struct svc_serv *nfsd_serv; + struct svc_info nfsd_info; +#define nfsd_serv nfsd_info.serv + /* When a listening socket is added to nfsd, keep_active is set * and this justifies a reference on nfsd_serv. This stops * nfsd_serv from being freed. When the number of threads is diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 8c84e77a8892..2923da1537d2 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -183,7 +183,7 @@ 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 = seq_release, }; DEFINE_SHOW_ATTRIBUTE(nfsd_reply_cache_stats); diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 32d06249b3c0..6927edf932e9 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -684,6 +684,7 @@ int nfsd_create_serv(struct net *net) return error; } spin_lock(&nfsd_notifier_lock); + nn->nfsd_info.mutex = &nfsd_mutex; nn->nfsd_serv = serv; spin_unlock(&nfsd_notifier_lock); @@ -1083,28 +1084,7 @@ bool nfssvc_encode_voidres(struct svc_rqst *rqstp, struct xdr_stream *xdr) int nfsd_pool_stats_open(struct inode *inode, struct file *file) { - 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) { - mutex_unlock(&nfsd_mutex); - return -ENODEV; - } - 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) -{ - 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(&nn->nfsd_info, file); } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 544fcfe07479..3bea2840272d 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -97,6 +97,12 @@ struct svc_serv { #endif /* CONFIG_SUNRPC_BACKCHANNEL */ }; +/* This is used by pool_stats to find and lock an svc */ +struct svc_info { + struct svc_serv *serv; + struct mutex *mutex; +}; + /** * svc_get() - increment reference count on a SUNRPC serv * @serv: the svc_serv to have count incremented @@ -431,7 +437,7 @@ 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_info *si, 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..dbb190606eec 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1363,29 +1363,36 @@ int svc_xprt_names(struct svc_serv *serv, char *buf, const int buflen) } EXPORT_SYMBOL_GPL(svc_xprt_names); - /*----------------------------------------------------------------------------*/ 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 svc_info *si = m->private; dprintk("svc_pool_stats_start, *pidx=%u\n", pidx); + mutex_lock(si->mutex); + if (!pidx) return SEQ_START_TOKEN; - return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]); + if (!si->serv) + return NULL; + return pidx > si->serv->sv_nrpools ? NULL + : &si->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 svc_info *si = m->private; + struct svc_serv *serv = si->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 +1407,9 @@ 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 svc_info *si = m->private; + + mutex_unlock(si->mutex); } static int svc_pool_stats_show(struct seq_file *m, void *p) @@ -1427,14 +1437,18 @@ 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_info *info, struct file *file) { + struct seq_file *seq; int err; err = seq_open(file, &svc_pool_stats_seq_ops); - if (!err) - ((struct seq_file *) file->private_data)->private = serv; - return err; + if (err) + return err; + seq = file->private_data; + seq->private = info; + + return 0; } EXPORT_SYMBOL(svc_pool_stats_open); -- 2.43.0