From df5e49c880ea0776806b8a9f8ab95e035272cf6f Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: SUNRPC: change svc_get() to return the svc. It is common for 'get' functions to return the object that was 'got', and there are a couple of places where users of svc_get() would be a little simpler if svc_get() did that. Make it so. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 0ae28ae6caf2..5d9568953fcd 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -120,9 +120,10 @@ struct svc_serv { * change the number of threads. Horrible, but there it is. * Should be called with the "service mutex" held. */ -static inline void svc_get(struct svc_serv *serv) +static inline struct svc_serv *svc_get(struct svc_serv *serv) { serv->sv_nrthreads++; + return serv; } /* -- cgit v1.2.3 From 8c62d12740a1450d2e8456d5747f440e10db281a Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: SUNRPC/NFSD: clean up get/put functions. svc_destroy() is poorly named - it doesn't necessarily destroy the svc, it might just reduce the ref count. nfsd_destroy() is poorly named for the same reason. This patch: - removes the refcount functionality from svc_destroy(), moving it to a new svc_put(). Almost all previous callers of svc_destroy() now call svc_put(). - renames nfsd_destroy() to nfsd_put() and improves the code, using the new svc_destroy() rather than svc_put() - removes a few comments that explain the important for balanced get/put calls. This should be obvious. The only non-trivial part of this is that svc_destroy() would call svc_sock_update() on a non-final decrement. It can no longer do that, and svc_put() isn't really a good place of it. This call is now made from svc_exit_thread() which seems like a good place. This makes the call *before* sv_nrthreads is decremented rather than after. This is not particularly important as the call just sets a flag which causes sv_nrthreads set be checked later. A subsequent patch will improve the ordering. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- fs/lockd/svc.c | 6 +----- fs/nfs/callback.c | 14 ++------------ fs/nfsd/nfsctl.c | 4 ++-- fs/nfsd/nfsd.h | 2 +- fs/nfsd/nfssvc.c | 30 ++++++++++++++++-------------- include/linux/sunrpc/svc.h | 26 +++++++++++++++++++++++--- net/sunrpc/svc.c | 19 +++++-------------- 7 files changed, 50 insertions(+), 51 deletions(-) (limited to 'include/linux') diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 2f50d5b2a8a4..135bd86ed3ad 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -431,10 +431,6 @@ static struct svc_serv *lockd_create_svc(void) * Check whether we're already up and running. */ if (nlmsvc_rqst) - /* - * Note: increase service usage, because later in case of error - * svc_destroy() will be called. - */ return svc_get(nlmsvc_rqst->rq_server); /* @@ -495,7 +491,7 @@ int lockd_up(struct net *net, const struct cred *cred) * so we exit through here on both success and failure. */ err_put: - svc_destroy(serv); + svc_put(serv); err_create: mutex_unlock(&nlmsvc_mutex); return error; diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index 6e5e742a42b8..edbc7579b4aa 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -267,10 +267,6 @@ static struct svc_serv *nfs_callback_create_svc(int minorversion) * Check whether we're already up and running. */ if (cb_info->serv) - /* - * Note: increase service usage, because later in case of error - * svc_destroy() will be called. - */ return svc_get(cb_info->serv); switch (minorversion) { @@ -333,16 +329,10 @@ int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt) goto err_start; cb_info->users++; - /* - * svc_create creates the svc_serv with sv_nrthreads == 1, and then - * svc_prepare_thread increments that. So we need to call svc_destroy - * on both success and failure so that the refcount is 1 when the - * thread exits. - */ err_net: if (!cb_info->users) cb_info->serv = NULL; - svc_destroy(serv); + svc_put(serv); err_create: mutex_unlock(&nfs_callback_mutex); return ret; @@ -368,7 +358,7 @@ void nfs_callback_down(int minorversion, struct net *net) if (cb_info->users == 0) { svc_get(serv); serv->sv_ops->svo_setup(serv, NULL, 0); - svc_destroy(serv); + svc_put(serv); dprintk("nfs_callback_down: service destroyed\n"); cb_info->serv = NULL; } diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index bf4c9996ad92..17521fada83f 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -743,7 +743,7 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred err = svc_addsock(nn->nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred); if (err < 0 && list_empty(&nn->nfsd_serv->sv_permsocks)) { - nfsd_destroy(net); + nfsd_put(net); return err; } @@ -796,7 +796,7 @@ out_err: if (!list_empty(&nn->nfsd_serv->sv_permsocks)) nn->nfsd_serv->sv_nrthreads--; else - nfsd_destroy(net); + nfsd_put(net); return err; } diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 498e5a489826..3e5008b475ff 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -97,7 +97,7 @@ int nfsd_pool_stats_open(struct inode *, struct file *); int nfsd_pool_stats_release(struct inode *, struct file *); void nfsd_shutdown_threads(struct net *net); -void nfsd_destroy(struct net *net); +void nfsd_put(struct net *net); bool i_am_nfsd(void); diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 80431921e5d7..a0a7564e6c73 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -623,7 +623,7 @@ void nfsd_shutdown_threads(struct net *net) svc_get(serv); /* Kill outstanding nfsd threads */ serv->sv_ops->svo_setup(serv, NULL, 0); - nfsd_destroy(net); + nfsd_put(net); mutex_unlock(&nfsd_mutex); /* Wait for shutdown of nfsd_serv to complete */ wait_for_completion(&nn->nfsd_shutdown_complete); @@ -656,7 +656,10 @@ int nfsd_create_serv(struct net *net) nn->nfsd_serv->sv_maxconn = nn->max_connections; error = svc_bind(nn->nfsd_serv, net); if (error < 0) { - svc_destroy(nn->nfsd_serv); + /* NOT nfsd_put() as notifiers (see below) haven't + * been set up yet. + */ + svc_put(nn->nfsd_serv); nfsd_complete_shutdown(net); return error; } @@ -697,16 +700,16 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net) return 0; } -void nfsd_destroy(struct net *net) +void nfsd_put(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); - int destroy = (nn->nfsd_serv->sv_nrthreads == 1); - if (destroy) + nn->nfsd_serv->sv_nrthreads -= 1; + if (nn->nfsd_serv->sv_nrthreads == 0) { svc_shutdown_net(nn->nfsd_serv, net); - svc_destroy(nn->nfsd_serv); - if (destroy) + svc_destroy(nn->nfsd_serv); nfsd_complete_shutdown(net); + } } int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) @@ -758,7 +761,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) if (err) break; } - nfsd_destroy(net); + nfsd_put(net); return err; } @@ -795,7 +798,7 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred) error = nfsd_startup_net(net, cred); if (error) - goto out_destroy; + goto out_put; error = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv, NULL, nrservs); if (error) @@ -808,8 +811,8 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred) out_shutdown: if (error < 0 && !nfsd_up_before) nfsd_shutdown_net(net); -out_destroy: - nfsd_destroy(net); /* Release server */ +out_put: + nfsd_put(net); out: mutex_unlock(&nfsd_mutex); return error; @@ -982,7 +985,7 @@ out: /* Release the thread */ svc_exit_thread(rqstp); - nfsd_destroy(net); + nfsd_put(net); /* Release module */ mutex_unlock(&nfsd_mutex); @@ -1109,8 +1112,7 @@ int nfsd_pool_stats_release(struct inode *inode, struct file *file) struct net *net = inode->i_sb->s_fs_info; mutex_lock(&nfsd_mutex); - /* this function really, really should have been called svc_put() */ - nfsd_destroy(net); + nfsd_put(net); mutex_unlock(&nfsd_mutex); return ret; } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 5d9568953fcd..73d56d33a36d 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -114,8 +114,13 @@ struct svc_serv { #endif /* CONFIG_SUNRPC_BACKCHANNEL */ }; -/* - * We use sv_nrthreads as a reference count. svc_destroy() drops +/** + * svc_get() - increment reference count on a SUNRPC serv + * @serv: the svc_serv to have count incremented + * + * Returns: the svc_serv that was passed in. + * + * We use sv_nrthreads as a reference count. svc_put() drops * this refcount, so we need to bump it up around operations that * change the number of threads. Horrible, but there it is. * Should be called with the "service mutex" held. @@ -126,6 +131,22 @@ static inline struct svc_serv *svc_get(struct svc_serv *serv) return serv; } +void svc_destroy(struct svc_serv *serv); + +/** + * svc_put - decrement reference count on a SUNRPC serv + * @serv: the svc_serv to have count decremented + * + * When the reference count reaches zero, svc_destroy() + * is called to clean up and free the serv. + */ +static inline void svc_put(struct svc_serv *serv) +{ + serv->sv_nrthreads -= 1; + if (serv->sv_nrthreads == 0) + svc_destroy(serv); +} + /* * Maximum payload size supported by a kernel RPC server. * This is use to determine the max number of pages nfsd is @@ -515,7 +536,6 @@ struct svc_serv * svc_create_pooled(struct svc_program *, unsigned int, int svc_set_num_threads(struct svc_serv *, struct svc_pool *, int); int svc_set_num_threads_sync(struct svc_serv *, struct svc_pool *, int); int svc_pool_stats_open(struct svc_serv *serv, struct file *file); -void svc_destroy(struct svc_serv *); void svc_shutdown_net(struct svc_serv *, struct net *); int svc_process(struct svc_rqst *); int bc_svc_process(struct svc_serv *, struct rpc_rqst *, diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 4292278a9552..55a1bf0d129f 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -528,17 +528,7 @@ EXPORT_SYMBOL_GPL(svc_shutdown_net); void svc_destroy(struct svc_serv *serv) { - dprintk("svc: svc_destroy(%s, %d)\n", - serv->sv_program->pg_name, - serv->sv_nrthreads); - - if (serv->sv_nrthreads) { - if (--(serv->sv_nrthreads) != 0) { - svc_sock_update_bufs(serv); - return; - } - } else - printk("svc_destroy: no threads for serv=%p!\n", serv); + dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name); del_timer_sync(&serv->sv_temptimer); @@ -892,9 +882,10 @@ svc_exit_thread(struct svc_rqst *rqstp) svc_rqst_free(rqstp); - /* Release the server */ - if (serv) - svc_destroy(serv); + if (!serv) + return; + svc_sock_update_bufs(serv); + svc_destroy(serv); } EXPORT_SYMBOL_GPL(svc_exit_thread); -- cgit v1.2.3 From ec52361df99b490f6af412b046df9799b92c1050 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: SUNRPC: stop using ->sv_nrthreads as a refcount The use of sv_nrthreads as a general refcount results in clumsy code, as is seen by various comments needed to explain the situation. This patch introduces a 'struct kref' and uses that for reference counting, leaving sv_nrthreads to be a pure count of threads. The kref is managed particularly in svc_get() and svc_put(), and also nfsd_put(); svc_destroy() now takes a pointer to the embedded kref, rather than to the serv. nfsd allows the svc_serv to exist with ->sv_nrhtreads being zero. This happens when a transport is created before the first thread is started. To support this, a 'keep_active' flag is introduced which holds a ref on the svc_serv. This is set when any listening socket is successfully added (unless there are running threads), and cleared when the number of threads is set. So when the last thread exits, the nfs_serv will be destroyed. The use of 'keep_active' replaces previous code which checked if there were any permanent sockets. We no longer clear ->rq_server when nfsd() exits. This was done to prevent svc_exit_thread() from calling svc_destroy(). Instead we take an extra reference to the svc_serv to prevent svc_destroy() from being called. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- fs/lockd/svc.c | 4 ---- fs/nfs/callback.c | 2 +- fs/nfsd/netns.h | 7 +++++++ fs/nfsd/nfsctl.c | 22 ++++++++++------------ fs/nfsd/nfssvc.c | 42 ++++++++++++++++++++++++++---------------- include/linux/sunrpc/svc.h | 14 ++++---------- net/sunrpc/svc.c | 22 +++++++++++----------- 7 files changed, 59 insertions(+), 54 deletions(-) (limited to 'include/linux') diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 135bd86ed3ad..a9669b106dbd 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -486,10 +486,6 @@ int lockd_up(struct net *net, const struct cred *cred) goto err_put; } nlmsvc_users++; - /* - * Note: svc_serv structures have an initial use count of 1, - * so we exit through here on both success and failure. - */ err_put: svc_put(serv); err_create: diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index edbc7579b4aa..d9d78ffd1d65 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -169,7 +169,7 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt, if (nrservs < NFS4_MIN_NR_CALLBACK_THREADS) nrservs = NFS4_MIN_NR_CALLBACK_THREADS; - if (serv->sv_nrthreads-1 == nrservs) + if (serv->sv_nrthreads == nrservs) return 0; ret = serv->sv_ops->svo_setup(serv, NULL, nrservs); diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index 935c1028c217..08bcd8f23b01 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -123,6 +123,13 @@ struct nfsd_net { u32 clverifier_counter; struct svc_serv *nfsd_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 + * set, keep_active is cleared and the reference is dropped. So + * when the last thread exits, the service will be destroyed. + */ + int keep_active; wait_queue_head_t ntf_wq; atomic_t ntf_refcnt; diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 17521fada83f..7b557eb8211a 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -742,13 +742,12 @@ static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred return err; err = svc_addsock(nn->nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred); - if (err < 0 && list_empty(&nn->nfsd_serv->sv_permsocks)) { - nfsd_put(net); - return err; - } - /* Decrease the count, but don't shut down the service */ - nn->nfsd_serv->sv_nrthreads--; + if (err >= 0 && + !nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1)) + svc_get(nn->nfsd_serv); + + nfsd_put(net); return err; } @@ -783,8 +782,10 @@ static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cr if (err < 0 && err != -EAFNOSUPPORT) goto out_close; - /* Decrease the count, but don't shut down the service */ - nn->nfsd_serv->sv_nrthreads--; + if (!nn->nfsd_serv->sv_nrthreads && !xchg(&nn->keep_active, 1)) + svc_get(nn->nfsd_serv); + + nfsd_put(net); return 0; out_close: xprt = svc_find_xprt(nn->nfsd_serv, transport, net, PF_INET, port); @@ -793,10 +794,7 @@ out_close: svc_xprt_put(xprt); } out_err: - if (!list_empty(&nn->nfsd_serv->sv_permsocks)) - nn->nfsd_serv->sv_nrthreads--; - else - nfsd_put(net); + nfsd_put(net); return err; } diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index a0a7564e6c73..5f605e7e8091 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -60,13 +60,13 @@ static __be32 nfsd_init_request(struct svc_rqst *, * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt * * If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a - * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number - * of nfsd threads must exist and each must listed in ->sp_all_threads in each - * entry of ->sv_pools[]. + * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0 (unless + * nn->keep_active is set). That number of nfsd threads must + * exist and each must be listed in ->sp_all_threads in some entry of + * ->sv_pools[]. * - * Transitions of the thread count between zero and non-zero are of particular - * interest since the svc_serv needs to be created and initialized at that - * point, or freed. + * Each active thread holds a counted reference on nn->nfsd_serv, as does + * the nn->keep_active flag and various transient calls to svc_get(). * * Finally, the nfsd_mutex also protects some of the global variables that are * accessed when nfsd starts and that are settable via the write_* routines in @@ -700,14 +700,22 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net) return 0; } +/* This is the callback for kref_put() below. + * There is no code here as the first thing to be done is + * call svc_shutdown_net(), but we cannot get the 'net' from + * the kref. So do all the work when kref_put returns true. + */ +static void nfsd_noop(struct kref *ref) +{ +} + void nfsd_put(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); - nn->nfsd_serv->sv_nrthreads -= 1; - if (nn->nfsd_serv->sv_nrthreads == 0) { + if (kref_put(&nn->nfsd_serv->sv_refcnt, nfsd_noop)) { svc_shutdown_net(nn->nfsd_serv, net); - svc_destroy(nn->nfsd_serv); + svc_destroy(&nn->nfsd_serv->sv_refcnt); nfsd_complete_shutdown(net); } } @@ -803,15 +811,14 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred) NULL, nrservs); if (error) goto out_shutdown; - /* We are holding a reference to nn->nfsd_serv which - * we don't want to count in the return value, - * so subtract 1 - */ - error = nn->nfsd_serv->sv_nrthreads - 1; + error = nn->nfsd_serv->sv_nrthreads; out_shutdown: if (error < 0 && !nfsd_up_before) nfsd_shutdown_net(net); out_put: + /* Threads now hold service active */ + if (xchg(&nn->keep_active, 0)) + nfsd_put(net); nfsd_put(net); out: mutex_unlock(&nfsd_mutex); @@ -980,11 +987,15 @@ nfsd(void *vrqstp) nfsdstats.th_cnt --; out: - rqstp->rq_server = NULL; + /* Take an extra ref so that the svc_put in svc_exit_thread() + * doesn't call svc_destroy() + */ + svc_get(nn->nfsd_serv); /* Release the thread */ svc_exit_thread(rqstp); + /* Now if needed we call svc_destroy in appropriate context */ nfsd_put(net); /* Release module */ @@ -1099,7 +1110,6 @@ int nfsd_pool_stats_open(struct inode *inode, struct file *file) mutex_unlock(&nfsd_mutex); return -ENODEV; } - /* bump up the psudo refcount while traversing */ svc_get(nn->nfsd_serv); ret = svc_pool_stats_open(nn->nfsd_serv, file); mutex_unlock(&nfsd_mutex); diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 73d56d33a36d..3903b4ae8ac5 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -85,6 +85,7 @@ struct svc_serv { struct svc_program * sv_program; /* RPC program */ struct svc_stat * sv_stats; /* RPC statistics */ spinlock_t sv_lock; + struct kref sv_refcnt; unsigned int sv_nrthreads; /* # of server threads */ unsigned int sv_maxconn; /* max connections allowed or * '0' causing max to be based @@ -119,19 +120,14 @@ struct svc_serv { * @serv: the svc_serv to have count incremented * * Returns: the svc_serv that was passed in. - * - * We use sv_nrthreads as a reference count. svc_put() drops - * this refcount, so we need to bump it up around operations that - * change the number of threads. Horrible, but there it is. - * Should be called with the "service mutex" held. */ static inline struct svc_serv *svc_get(struct svc_serv *serv) { - serv->sv_nrthreads++; + kref_get(&serv->sv_refcnt); return serv; } -void svc_destroy(struct svc_serv *serv); +void svc_destroy(struct kref *); /** * svc_put - decrement reference count on a SUNRPC serv @@ -142,9 +138,7 @@ void svc_destroy(struct svc_serv *serv); */ static inline void svc_put(struct svc_serv *serv) { - serv->sv_nrthreads -= 1; - if (serv->sv_nrthreads == 0) - svc_destroy(serv); + kref_put(&serv->sv_refcnt, svc_destroy); } /* diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 55a1bf0d129f..acddc6e12e9e 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -435,7 +435,7 @@ __svc_create(struct svc_program *prog, unsigned int bufsize, int npools, return NULL; serv->sv_name = prog->pg_name; serv->sv_program = prog; - serv->sv_nrthreads = 1; + kref_init(&serv->sv_refcnt); serv->sv_stats = prog->pg_stats; if (bufsize > RPCSVC_MAXPAYLOAD) bufsize = RPCSVC_MAXPAYLOAD; @@ -526,10 +526,11 @@ EXPORT_SYMBOL_GPL(svc_shutdown_net); * protect the sv_nrthreads, sv_permsocks and sv_tempsocks. */ void -svc_destroy(struct svc_serv *serv) +svc_destroy(struct kref *ref) { - dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name); + struct svc_serv *serv = container_of(ref, struct svc_serv, sv_refcnt); + dprintk("svc: svc_destroy(%s)\n", serv->sv_program->pg_name); del_timer_sync(&serv->sv_temptimer); /* @@ -637,6 +638,7 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) if (!rqstp) return ERR_PTR(-ENOMEM); + svc_get(serv); serv->sv_nrthreads++; spin_lock_bh(&pool->sp_lock); pool->sp_nrthreads++; @@ -776,8 +778,7 @@ int svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { if (pool == NULL) { - /* The -1 assumes caller has done a svc_get() */ - nrservs -= (serv->sv_nrthreads-1); + nrservs -= serv->sv_nrthreads; } else { spin_lock_bh(&pool->sp_lock); nrservs -= pool->sp_nrthreads; @@ -814,8 +815,7 @@ int svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { if (pool == NULL) { - /* The -1 assumes caller has done a svc_get() */ - nrservs -= (serv->sv_nrthreads-1); + nrservs -= serv->sv_nrthreads; } else { spin_lock_bh(&pool->sp_lock); nrservs -= pool->sp_nrthreads; @@ -880,12 +880,12 @@ svc_exit_thread(struct svc_rqst *rqstp) list_del_rcu(&rqstp->rq_all); spin_unlock_bh(&pool->sp_lock); + serv->sv_nrthreads -= 1; + svc_sock_update_bufs(serv); + svc_rqst_free(rqstp); - if (!serv) - return; - svc_sock_update_bufs(serv); - svc_destroy(serv); + svc_put(serv); } EXPORT_SYMBOL_GPL(svc_exit_thread); -- cgit v1.2.3 From 3409e4f1e8f239f0ed81be0b068ecf4e73e2e826 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: NFSD: Make it possible to use svc_set_num_threads_sync nfsd cannot currently use svc_set_num_threads_sync. It instead uses svc_set_num_threads which does *not* wait for threads to all exit, and has a separate mechanism (nfsd_shutdown_complete) to wait for completion. The reason that nfsd is unlike other services is that nfsd threads can exit separately from svc_set_num_threads being called - they die on receipt of SIGKILL. Also, when the last thread exits, the service must be shut down (sockets closed). For this, the nfsd_mutex needs to be taken, and as that mutex needs to be held while svc_set_num_threads is called, the one cannot wait for the other. This patch changes the nfsd thread so that it can drop the ref on the service without blocking on nfsd_mutex, so that svc_set_num_threads_sync can be used: - if it can drop a non-last reference, it does that. This does not trigger shutdown and does not require a mutex. This will likely happen for all but the last thread signalled, and for all threads being shut down by nfsd_shutdown_threads() - if it can get the mutex without blocking (trylock), it does that and then drops the reference. This will likely happen for the last thread killed by SIGKILL - Otherwise there might be an unrelated task holding the mutex, possibly in another network namespace, or nfsd_shutdown_threads() might be just about to get a reference on the service, after which we can drop ours safely. We cannot conveniently get wakeup notifications on these events, and we are unlikely to need to, so we sleep briefly and check again. With this we can discard nfsd_shutdown_complete and nfsd_complete_shutdown(), and switch to svc_set_num_threads_sync. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- fs/nfsd/netns.h | 3 --- fs/nfsd/nfssvc.c | 41 ++++++++++++++++++++--------------------- include/linux/sunrpc/svc.h | 13 +++++++++++++ 3 files changed, 33 insertions(+), 24 deletions(-) (limited to 'include/linux') diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index 08bcd8f23b01..1fd59eb0730b 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -134,9 +134,6 @@ struct nfsd_net { wait_queue_head_t ntf_wq; atomic_t ntf_refcnt; - /* Allow umount to wait for nfsd state cleanup */ - struct completion nfsd_shutdown_complete; - /* * clientid and stateid data for construction of net unique COPY * stateids. diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index 097abd8b059c..d0d9107a1b93 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -593,20 +593,10 @@ static const struct svc_serv_ops nfsd_thread_sv_ops = { .svo_shutdown = nfsd_last_thread, .svo_function = nfsd, .svo_enqueue_xprt = svc_xprt_do_enqueue, - .svo_setup = svc_set_num_threads, + .svo_setup = svc_set_num_threads_sync, .svo_module = THIS_MODULE, }; -static void nfsd_complete_shutdown(struct net *net) -{ - struct nfsd_net *nn = net_generic(net, nfsd_net_id); - - WARN_ON(!mutex_is_locked(&nfsd_mutex)); - - nn->nfsd_serv = NULL; - complete(&nn->nfsd_shutdown_complete); -} - void nfsd_shutdown_threads(struct net *net) { struct nfsd_net *nn = net_generic(net, nfsd_net_id); @@ -624,8 +614,6 @@ void nfsd_shutdown_threads(struct net *net) serv->sv_ops->svo_setup(serv, NULL, 0); nfsd_put(net); mutex_unlock(&nfsd_mutex); - /* Wait for shutdown of nfsd_serv to complete */ - wait_for_completion(&nn->nfsd_shutdown_complete); } bool i_am_nfsd(void) @@ -650,7 +638,6 @@ int nfsd_create_serv(struct net *net) &nfsd_thread_sv_ops); if (nn->nfsd_serv == NULL) return -ENOMEM; - init_completion(&nn->nfsd_shutdown_complete); nn->nfsd_serv->sv_maxconn = nn->max_connections; error = svc_bind(nn->nfsd_serv, net); @@ -659,7 +646,7 @@ int nfsd_create_serv(struct net *net) * been set up yet. */ svc_put(nn->nfsd_serv); - nfsd_complete_shutdown(net); + nn->nfsd_serv = NULL; return error; } @@ -715,7 +702,7 @@ void nfsd_put(struct net *net) if (kref_put(&nn->nfsd_serv->sv_refcnt, nfsd_noop)) { svc_shutdown_net(nn->nfsd_serv, net); svc_destroy(&nn->nfsd_serv->sv_refcnt); - nfsd_complete_shutdown(net); + nn->nfsd_serv = NULL; } } @@ -743,7 +730,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) 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; + int new = nthreads[i] * NFSD_MAXSERVS / tot; tot -= (nthreads[i] - new); nthreads[i] = new; } @@ -989,10 +976,22 @@ out: /* Release the thread */ svc_exit_thread(rqstp); - /* Now if needed we call svc_destroy in appropriate context */ - mutex_lock(&nfsd_mutex); - nfsd_put(net); - mutex_unlock(&nfsd_mutex); + /* We need to drop a ref, but may not drop the last reference + * without holding nfsd_mutex, and we cannot wait for nfsd_mutex as that + * could deadlock with nfsd_shutdown_threads() waiting for us. + * So three options are: + * - drop a non-final reference, + * - get the mutex without waiting + * - sleep briefly andd try the above again + */ + while (!svc_put_not_last(nn->nfsd_serv)) { + if (mutex_trylock(&nfsd_mutex)) { + nfsd_put(net); + mutex_unlock(&nfsd_mutex); + break; + } + msleep(20); + } /* Release module */ module_put_and_exit(0); diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 3903b4ae8ac5..36bfc0281988 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -141,6 +141,19 @@ static inline void svc_put(struct svc_serv *serv) kref_put(&serv->sv_refcnt, svc_destroy); } +/** + * svc_put_not_last - decrement non-final reference count on SUNRPC serv + * @serv: the svc_serv to have count decremented + * + * Returns: %true is refcount was decremented. + * + * If the refcount is 1, it is not decremented and instead failure is reported. + */ +static inline bool svc_put_not_last(struct svc_serv *serv) +{ + return refcount_dec_not_one(&serv->sv_refcnt.refcount); +} + /* * Maximum payload size supported by a kernel RPC server. * This is use to determine the max number of pages nfsd is -- cgit v1.2.3 From 3ebdbe5203a874614819700d3f470724cb803709 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: SUNRPC: discard svo_setup and rename svc_set_num_threads_sync() The ->svo_setup callback serves no purpose. It is always called from within the same module that chooses which callback is needed. So discard it and call the relevant function directly. Now that svc_set_num_threads() is no longer used remove it and rename svc_set_num_threads_sync() to remove the "_sync" suffix. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- fs/nfs/callback.c | 8 +++----- fs/nfsd/nfssvc.c | 11 +++++------ include/linux/sunrpc/svc.h | 4 ---- net/sunrpc/svc.c | 49 ++-------------------------------------------- 4 files changed, 10 insertions(+), 62 deletions(-) (limited to 'include/linux') diff --git a/fs/nfs/callback.c b/fs/nfs/callback.c index d9d78ffd1d65..6cdc9d18a7dd 100644 --- a/fs/nfs/callback.c +++ b/fs/nfs/callback.c @@ -172,9 +172,9 @@ static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt, if (serv->sv_nrthreads == nrservs) return 0; - ret = serv->sv_ops->svo_setup(serv, NULL, nrservs); + ret = svc_set_num_threads(serv, NULL, nrservs); if (ret) { - serv->sv_ops->svo_setup(serv, NULL, 0); + svc_set_num_threads(serv, NULL, 0); return ret; } dprintk("nfs_callback_up: service started\n"); @@ -235,14 +235,12 @@ err_bind: static const struct svc_serv_ops nfs40_cb_sv_ops = { .svo_function = nfs4_callback_svc, .svo_enqueue_xprt = svc_xprt_do_enqueue, - .svo_setup = svc_set_num_threads_sync, .svo_module = THIS_MODULE, }; #if defined(CONFIG_NFS_V4_1) static const struct svc_serv_ops nfs41_cb_sv_ops = { .svo_function = nfs41_callback_svc, .svo_enqueue_xprt = svc_xprt_do_enqueue, - .svo_setup = svc_set_num_threads_sync, .svo_module = THIS_MODULE, }; @@ -357,7 +355,7 @@ void nfs_callback_down(int minorversion, struct net *net) cb_info->users--; if (cb_info->users == 0) { svc_get(serv); - serv->sv_ops->svo_setup(serv, NULL, 0); + svc_set_num_threads(serv, NULL, 0); svc_put(serv); dprintk("nfs_callback_down: service destroyed\n"); cb_info->serv = NULL; diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c index d0d9107a1b93..020156e96bdb 100644 --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -593,7 +593,6 @@ static const struct svc_serv_ops nfsd_thread_sv_ops = { .svo_shutdown = nfsd_last_thread, .svo_function = nfsd, .svo_enqueue_xprt = svc_xprt_do_enqueue, - .svo_setup = svc_set_num_threads_sync, .svo_module = THIS_MODULE, }; @@ -611,7 +610,7 @@ void nfsd_shutdown_threads(struct net *net) svc_get(serv); /* Kill outstanding nfsd threads */ - serv->sv_ops->svo_setup(serv, NULL, 0); + svc_set_num_threads(serv, NULL, 0); nfsd_put(net); mutex_unlock(&nfsd_mutex); } @@ -750,8 +749,9 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net) /* apply the new numbers */ svc_get(nn->nfsd_serv); for (i = 0; i < n; i++) { - err = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv, - &nn->nfsd_serv->sv_pools[i], nthreads[i]); + err = svc_set_num_threads(nn->nfsd_serv, + &nn->nfsd_serv->sv_pools[i], + nthreads[i]); if (err) break; } @@ -793,8 +793,7 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred) error = nfsd_startup_net(net, cred); if (error) goto out_put; - error = nn->nfsd_serv->sv_ops->svo_setup(nn->nfsd_serv, - NULL, nrservs); + error = svc_set_num_threads(nn->nfsd_serv, NULL, nrservs); if (error) goto out_shutdown; error = nn->nfsd_serv->sv_nrthreads; diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 36bfc0281988..0b38c6eaf985 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -64,9 +64,6 @@ struct svc_serv_ops { /* queue up a transport for servicing */ void (*svo_enqueue_xprt)(struct svc_xprt *); - /* set up thread (or whatever) execution context */ - int (*svo_setup)(struct svc_serv *, struct svc_pool *, int); - /* optional module to count when adding threads (pooled svcs only) */ struct module *svo_module; }; @@ -541,7 +538,6 @@ void svc_pool_map_put(void); struct svc_serv * svc_create_pooled(struct svc_program *, unsigned int, const struct svc_serv_ops *); int svc_set_num_threads(struct svc_serv *, struct svc_pool *, int); -int svc_set_num_threads_sync(struct svc_serv *, struct svc_pool *, int); int svc_pool_stats_open(struct svc_serv *serv, struct file *file); void svc_shutdown_net(struct svc_serv *, struct net *); int svc_process(struct svc_rqst *); diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 2b2042234e4b..5513f8c9a8d6 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -743,58 +743,13 @@ svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) return 0; } - -/* destroy old threads */ -static int -svc_signal_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) -{ - struct task_struct *task; - unsigned int state = serv->sv_nrthreads-1; - - /* destroy old threads */ - do { - task = choose_victim(serv, pool, &state); - if (task == NULL) - break; - send_sig(SIGINT, task, 1); - nrservs++; - } while (nrservs < 0); - - return 0; -} - /* * Create or destroy enough new threads to make the number * of threads the given number. If `pool' is non-NULL, applies * only to threads in that pool, otherwise round-robins between * all pools. Caller must ensure that mutual exclusion between this and * server startup or shutdown. - * - * Destroying threads relies on the service threads filling in - * rqstp->rq_task, which only the nfs ones do. Assumes the serv - * has been created using svc_create_pooled(). - * - * Based on code that used to be in nfsd_svc() but tweaked - * to be pool-aware. */ -int -svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) -{ - if (pool == NULL) { - nrservs -= serv->sv_nrthreads; - } else { - spin_lock_bh(&pool->sp_lock); - nrservs -= pool->sp_nrthreads; - spin_unlock_bh(&pool->sp_lock); - } - - if (nrservs > 0) - return svc_start_kthreads(serv, pool, nrservs); - if (nrservs < 0) - return svc_signal_kthreads(serv, pool, nrservs); - return 0; -} -EXPORT_SYMBOL_GPL(svc_set_num_threads); /* destroy old threads */ static int @@ -815,7 +770,7 @@ svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) } int -svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrservs) +svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs) { if (pool == NULL) { nrservs -= serv->sv_nrthreads; @@ -831,7 +786,7 @@ svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrser return svc_stop_kthreads(serv, pool, nrservs); return 0; } -EXPORT_SYMBOL_GPL(svc_set_num_threads_sync); +EXPORT_SYMBOL_GPL(svc_set_num_threads); /** * svc_rqst_replace_page - Replace one page in rq_pages[] -- cgit v1.2.3 From cf0e124e0a489944d08fcc3c694d2b234d2cc658 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: SUNRPC: move the pool_map definitions (back) into svc.c These definitions are not used outside of svc.c, and there is no evidence that they ever have been. So move them into svc.c and make the declarations 'static'. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- include/linux/sunrpc/svc.h | 25 ------------------------- net/sunrpc/svc.c | 31 +++++++++++++++++++++++++------ 2 files changed, 25 insertions(+), 31 deletions(-) (limited to 'include/linux') diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index 0b38c6eaf985..d69e6108cb83 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -494,29 +494,6 @@ struct svc_procedure { const char * pc_name; /* for display */ }; -/* - * Mode for mapping cpus to pools. - */ -enum { - SVC_POOL_AUTO = -1, /* choose one of the others */ - SVC_POOL_GLOBAL, /* no mapping, just a single global pool - * (legacy & UP mode) */ - SVC_POOL_PERCPU, /* one pool per cpu */ - SVC_POOL_PERNODE /* one pool per numa node */ -}; - -struct svc_pool_map { - int count; /* How many svc_servs use us */ - int mode; /* Note: int not enum to avoid - * warnings about "enumeration value - * not handled in switch" */ - unsigned int npools; - unsigned int *pool_to; /* maps pool id to cpu or node */ - unsigned int *to_pool; /* maps cpu or node to pool id */ -}; - -extern struct svc_pool_map svc_pool_map; - /* * Function prototypes. */ @@ -533,8 +510,6 @@ void svc_rqst_replace_page(struct svc_rqst *rqstp, struct page *page); void svc_rqst_free(struct svc_rqst *); void svc_exit_thread(struct svc_rqst *); -unsigned int svc_pool_map_get(void); -void svc_pool_map_put(void); struct svc_serv * svc_create_pooled(struct svc_program *, unsigned int, const struct svc_serv_ops *); int svc_set_num_threads(struct svc_serv *, struct svc_pool *, int); diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 5513f8c9a8d6..f0dd9ef7e0cd 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -41,14 +41,35 @@ static void svc_unregister(const struct svc_serv *serv, struct net *net); #define SVC_POOL_DEFAULT SVC_POOL_GLOBAL +/* + * Mode for mapping cpus to pools. + */ +enum { + SVC_POOL_AUTO = -1, /* choose one of the others */ + SVC_POOL_GLOBAL, /* no mapping, just a single global pool + * (legacy & UP mode) */ + SVC_POOL_PERCPU, /* one pool per cpu */ + SVC_POOL_PERNODE /* one pool per numa node */ +}; + /* * Structure for mapping cpus to pools and vice versa. * Setup once during sunrpc initialisation. */ -struct svc_pool_map svc_pool_map = { + +struct svc_pool_map { + int count; /* How many svc_servs use us */ + int mode; /* Note: int not enum to avoid + * warnings about "enumeration value + * not handled in switch" */ + unsigned int npools; + unsigned int *pool_to; /* maps pool id to cpu or node */ + unsigned int *to_pool; /* maps cpu or node to pool id */ +}; + +static struct svc_pool_map svc_pool_map = { .mode = SVC_POOL_DEFAULT }; -EXPORT_SYMBOL_GPL(svc_pool_map); static DEFINE_MUTEX(svc_pool_map_mutex);/* protects svc_pool_map.count only */ @@ -222,7 +243,7 @@ svc_pool_map_init_pernode(struct svc_pool_map *m) * vice versa). Initialise the map if we're the first user. * Returns the number of pools. */ -unsigned int +static unsigned int svc_pool_map_get(void) { struct svc_pool_map *m = &svc_pool_map; @@ -257,7 +278,6 @@ svc_pool_map_get(void) mutex_unlock(&svc_pool_map_mutex); return m->npools; } -EXPORT_SYMBOL_GPL(svc_pool_map_get); /* * Drop a reference to the global map of cpus to pools. @@ -266,7 +286,7 @@ EXPORT_SYMBOL_GPL(svc_pool_map_get); * mode using the pool_mode module option without * rebooting or re-loading sunrpc.ko. */ -void +static void svc_pool_map_put(void) { struct svc_pool_map *m = &svc_pool_map; @@ -283,7 +303,6 @@ svc_pool_map_put(void) mutex_unlock(&svc_pool_map_mutex); } -EXPORT_SYMBOL_GPL(svc_pool_map_put); static int svc_pool_map_get_node(unsigned int pidx) { -- cgit v1.2.3 From 6b044fbaab02292fedb17565dbb3f2528083b169 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 29 Nov 2021 15:51:25 +1100 Subject: lockd: use svc_set_num_threads() for thread start and stop svc_set_num_threads() does everything that lockd_start_svc() does, except set sv_maxconn. It also (when passed 0) finds the threads and stops them with kthread_stop(). So move the setting for sv_maxconn, and use svc_set_num_thread() We now don't need nlmsvc_task. Now that we use svc_set_num_threads() it makes sense to set svo_module. This request that the thread exists with module_put_and_exit(). Also fix the documentation for svo_module to make this explicit. svc_prepare_thread is now only used where it is defined, so it can be made static. Signed-off-by: NeilBrown Signed-off-by: Chuck Lever --- fs/lockd/svc.c | 58 +++++++--------------------------------------- include/linux/sunrpc/svc.h | 6 ++--- net/sunrpc/svc.c | 3 +-- 3 files changed, 12 insertions(+), 55 deletions(-) (limited to 'include/linux') diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c index 1a7c11118b32..4defefd89cbf 100644 --- a/fs/lockd/svc.c +++ b/fs/lockd/svc.c @@ -55,7 +55,6 @@ EXPORT_SYMBOL_GPL(nlmsvc_ops); static DEFINE_MUTEX(nlmsvc_mutex); static unsigned int nlmsvc_users; static struct svc_serv *nlmsvc_serv; -static struct task_struct *nlmsvc_task; unsigned long nlmsvc_timeout; unsigned int lockd_net_id; @@ -186,7 +185,7 @@ lockd(void *vrqstp) svc_exit_thread(rqstp); - return 0; + module_put_and_exit(0); } static int create_lockd_listener(struct svc_serv *serv, const char *name, @@ -292,8 +291,8 @@ static void lockd_down_net(struct svc_serv *serv, struct net *net) __func__, net->ns.inum); } } else { - pr_err("%s: no users! task=%p, net=%x\n", - __func__, nlmsvc_task, net->ns.inum); + pr_err("%s: no users! net=%x\n", + __func__, net->ns.inum); BUG(); } } @@ -351,49 +350,11 @@ static struct notifier_block lockd_inet6addr_notifier = { }; #endif -static int lockd_start_svc(struct svc_serv *serv) -{ - int error; - struct svc_rqst *rqst; - - /* - * Create the kernel thread and wait for it to start. - */ - rqst = svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE); - if (IS_ERR(rqst)) { - error = PTR_ERR(rqst); - printk(KERN_WARNING - "lockd_up: svc_rqst allocation failed, error=%d\n", - error); - goto out_rqst; - } - - svc_sock_update_bufs(serv); - serv->sv_maxconn = nlm_max_connections; - - nlmsvc_task = kthread_create(lockd, rqst, "%s", serv->sv_name); - if (IS_ERR(nlmsvc_task)) { - error = PTR_ERR(nlmsvc_task); - printk(KERN_WARNING - "lockd_up: kthread_run failed, error=%d\n", error); - goto out_task; - } - rqst->rq_task = nlmsvc_task; - wake_up_process(nlmsvc_task); - - dprintk("lockd_up: service started\n"); - return 0; - -out_task: - svc_exit_thread(rqst); - nlmsvc_task = NULL; -out_rqst: - return error; -} - static const struct svc_serv_ops lockd_sv_ops = { .svo_shutdown = svc_rpcb_cleanup, + .svo_function = lockd, .svo_enqueue_xprt = svc_xprt_do_enqueue, + .svo_module = THIS_MODULE, }; static int lockd_get(void) @@ -425,7 +386,8 @@ static int lockd_get(void) return -ENOMEM; } - error = lockd_start_svc(serv); + serv->sv_maxconn = nlm_max_connections; + error = svc_set_num_threads(serv, NULL, 1); /* The thread now holds the only reference */ svc_put(serv); if (error < 0) @@ -453,11 +415,7 @@ static void lockd_put(void) unregister_inet6addr_notifier(&lockd_inet6addr_notifier); #endif - if (nlmsvc_task) { - kthread_stop(nlmsvc_task); - dprintk("lockd_down: service stopped\n"); - nlmsvc_task = NULL; - } + svc_set_num_threads(nlmsvc_serv, NULL, 0); nlmsvc_serv = NULL; dprintk("lockd_down: service destroyed\n"); } diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h index d69e6108cb83..cf175d47c6b7 100644 --- a/include/linux/sunrpc/svc.h +++ b/include/linux/sunrpc/svc.h @@ -64,7 +64,9 @@ struct svc_serv_ops { /* queue up a transport for servicing */ void (*svo_enqueue_xprt)(struct svc_xprt *); - /* optional module to count when adding threads (pooled svcs only) */ + /* optional module to count when adding threads. + * Thread function must call module_put_and_exit() to exit. + */ struct module *svo_module; }; @@ -504,8 +506,6 @@ struct svc_serv *svc_create(struct svc_program *, unsigned int, const struct svc_serv_ops *); struct svc_rqst *svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node); -struct svc_rqst *svc_prepare_thread(struct svc_serv *serv, - struct svc_pool *pool, int node); void svc_rqst_replace_page(struct svc_rqst *rqstp, struct page *page); void svc_rqst_free(struct svc_rqst *); diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index 5fbe7f55289e..2aabec2b4bec 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -652,7 +652,7 @@ out_enomem: } EXPORT_SYMBOL_GPL(svc_rqst_alloc); -struct svc_rqst * +static struct svc_rqst * svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) { struct svc_rqst *rqstp; @@ -672,7 +672,6 @@ svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node) spin_unlock_bh(&pool->sp_lock); return rqstp; } -EXPORT_SYMBOL_GPL(svc_prepare_thread); /* * Choose a pool in which to create a new thread, for svc_set_num_threads -- cgit v1.2.3 From 40595cdc93edf4110c0f0c0b06f8d82008f23929 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Thu, 16 Dec 2021 12:20:13 -0500 Subject: nfs: block notification on fs with its own ->lock NFSv4.1 supports an optional lock notification feature which notifies the client when a lock comes available. (Normally NFSv4 clients just poll for locks if necessary.) To make that work, we need to request a blocking lock from the filesystem. We turned that off for NFS in commit f657f8eef3ff ("nfs: don't atempt blocking locks on nfs reexports") [sic] because it actually blocks the nfsd thread while waiting for the lock. Thanks to Vasily Averin for pointing out that NFS isn't the only filesystem with that problem. Any filesystem that leaves ->lock NULL will use posix_lock_file(), which does the right thing. Simplest is just to assume that any filesystem that defines its own ->lock is not safe to request a blocking lock from. So, this patch mostly reverts commit f657f8eef3ff ("nfs: don't atempt blocking locks on nfs reexports") [sic] and commit b840be2f00c0 ("lockd: don't attempt blocking locks on nfs reexports"), and instead uses a check of ->lock (Vasily's suggestion) to decide whether to support blocking lock notifications on a given filesystem. Also add a little documentation. Perhaps someday we could add back an export flag later to allow filesystems with "good" ->lock methods to support blocking lock notifications. Reported-by: Vasily Averin Signed-off-by: J. Bruce Fields [ cel: Description rewritten to address checkpatch nits ] [ cel: Fixed warning when SUNRPC debugging is disabled ] [ cel: Fixed NULL check ] Signed-off-by: Chuck Lever Reviewed-by: Vasily Averin --- fs/lockd/svclock.c | 6 ++++-- fs/nfs/export.c | 2 +- fs/nfsd/nfs4state.c | 18 ++++++++++++------ include/linux/exportfs.h | 2 -- include/linux/lockd/lockd.h | 9 +++++++-- 5 files changed, 24 insertions(+), 13 deletions(-) (limited to 'include/linux') diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index e9b85d8fd5fe..cb3658ab9b7a 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -470,8 +470,10 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, struct nlm_host *host, struct nlm_lock *lock, int wait, struct nlm_cookie *cookie, int reclaim) { - struct nlm_block *block = NULL; +#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) struct inode *inode = nlmsvc_file_inode(file); +#endif + struct nlm_block *block = NULL; int error; int mode; int async_block = 0; @@ -484,7 +486,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, (long long)lock->fl.fl_end, wait); - if (inode->i_sb->s_export_op->flags & EXPORT_OP_SYNC_LOCKS) { + if (nlmsvc_file_file(file)->f_op->lock) { async_block = wait; wait = 0; } diff --git a/fs/nfs/export.c b/fs/nfs/export.c index 171c424cb6d5..01596f2d0a1e 100644 --- a/fs/nfs/export.c +++ b/fs/nfs/export.c @@ -158,5 +158,5 @@ const struct export_operations nfs_export_ops = { .fetch_iversion = nfs_fetch_iversion, .flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK| EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS| - EXPORT_OP_NOATOMIC_ATTR|EXPORT_OP_SYNC_LOCKS, + EXPORT_OP_NOATOMIC_ATTR, }; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 72e3833c3034..d8faccc55479 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6842,7 +6842,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_blocked_lock *nbl = NULL; struct file_lock *file_lock = NULL; struct file_lock *conflock = NULL; - struct super_block *sb; __be32 status = 0; int lkflg; int err; @@ -6864,7 +6863,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, dprintk("NFSD: nfsd4_lock: permission denied!\n"); return status; } - sb = cstate->current_fh.fh_dentry->d_sb; if (lock->lk_is_new) { if (nfsd4_has_session(cstate)) @@ -6916,8 +6914,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, fp = lock_stp->st_stid.sc_file; switch (lock->lk_type) { case NFS4_READW_LT: - if (nfsd4_has_session(cstate) && - !(sb->s_export_op->flags & EXPORT_OP_SYNC_LOCKS)) + if (nfsd4_has_session(cstate)) fl_flags |= FL_SLEEP; fallthrough; case NFS4_READ_LT: @@ -6929,8 +6926,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, fl_type = F_RDLCK; break; case NFS4_WRITEW_LT: - if (nfsd4_has_session(cstate) && - !(sb->s_export_op->flags & EXPORT_OP_SYNC_LOCKS)) + if (nfsd4_has_session(cstate)) fl_flags |= FL_SLEEP; fallthrough; case NFS4_WRITE_LT: @@ -6951,6 +6947,16 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, goto out; } + /* + * Most filesystems with their own ->lock operations will block + * the nfsd thread waiting to acquire the lock. That leads to + * deadlocks (we don't want every nfsd thread tied up waiting + * for file locks), so don't attempt blocking lock notifications + * on those filesystems: + */ + if (nf->nf_file->f_op->lock) + fl_flags &= ~FL_SLEEP; + nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn); if (!nbl) { dprintk("NFSD: %s: unable to allocate block!\n", __func__); diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index 3260fe714846..fe848901fcc3 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -221,8 +221,6 @@ struct export_operations { #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply atomic attribute updates */ -#define EXPORT_OP_SYNC_LOCKS (0x20) /* Filesystem can't do - asychronous blocking locks */ unsigned long flags; }; diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h index c4ae6506b8b3..fcef192e5e45 100644 --- a/include/linux/lockd/lockd.h +++ b/include/linux/lockd/lockd.h @@ -303,10 +303,15 @@ void nlmsvc_invalidate_all(void); int nlmsvc_unlock_all_by_sb(struct super_block *sb); int nlmsvc_unlock_all_by_ip(struct sockaddr *server_addr); +static inline struct file *nlmsvc_file_file(struct nlm_file *file) +{ + return file->f_file[O_RDONLY] ? + file->f_file[O_RDONLY] : file->f_file[O_WRONLY]; +} + static inline struct inode *nlmsvc_file_inode(struct nlm_file *file) { - return locks_inode(file->f_file[O_RDONLY] ? - file->f_file[O_RDONLY] : file->f_file[O_WRONLY]); + return locks_inode(nlmsvc_file_file(file)); } static inline int __nlm_privileged_request4(const struct sockaddr *sap) -- cgit v1.2.3 From 0ea9fc15b1d7d6636d429e74ffe3f86bf2f2f7d6 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Tue, 23 Nov 2021 17:05:07 +0100 Subject: fs/locks: fix fcntl_getlk64/fcntl_setlk64 stub prototypes My patch to rework oabi fcntl64() introduced a harmless sparse warning when file locking is disabled: arch/arm/kernel/sys_oabi-compat.c:251:51: sparse: sparse: incorrect type in argument 3 (different address spaces) @@ expected struct flock64 [noderef] __user *user @@ got struct flock64 * @@ arch/arm/kernel/sys_oabi-compat.c:251:51: sparse: expected struct flock64 [noderef] __user *user arch/arm/kernel/sys_oabi-compat.c:251:51: sparse: got struct flock64 * arch/arm/kernel/sys_oabi-compat.c:265:55: sparse: sparse: incorrect type in argument 4 (different address spaces) @@ expected struct flock64 [noderef] __user *user @@ got struct flock64 * @@ arch/arm/kernel/sys_oabi-compat.c:265:55: sparse: expected struct flock64 [noderef] __user *user arch/arm/kernel/sys_oabi-compat.c:265:55: sparse: got struct flock64 * When file locking is enabled, everything works correctly and the right data gets passed, but the stub declarations in linux/fs.h did not get modified when the calling conventions changed in an earlier patch. Reported-by: kernel test robot Fixes: 7e2d8c29ecdd ("ARM: 9111/1: oabi-compat: rework fcntl64() emulation") Fixes: a75d30c77207 ("fs/locks: pass kernel struct flock to fcntl_getlk/setlk") Cc: Christoph Hellwig Reviewed-by: Christoph Hellwig Acked-by: Christian Brauner Signed-off-by: Arnd Bergmann Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever --- include/linux/fs.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/fs.h b/include/linux/fs.h index bbf812ce89a8..5122d13775c2 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1220,13 +1220,13 @@ static inline int fcntl_setlk(unsigned int fd, struct file *file, #if BITS_PER_LONG == 32 static inline int fcntl_getlk64(struct file *file, unsigned int cmd, - struct flock64 __user *user) + struct flock64 *user) { return -EINVAL; } static inline int fcntl_setlk64(unsigned int fd, struct file *file, - unsigned int cmd, struct flock64 __user *user) + unsigned int cmd, struct flock64 *user) { return -EACCES; } -- cgit v1.2.3