From 0cc11a61b80a1ab1d12f1597b27b8b45ef8bac4a Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 20 Oct 2016 09:34:31 -0400 Subject: [PATCH] nfsd: move blocked lock handling under a dedicated spinlock Bruce was hitting some lockdep warnings in testing, showing that we could hit a deadlock with the new CB_NOTIFY_LOCK handling, involving a rather complex situation involving four different spinlocks. The crux of the matter is that we end up taking the nn->client_lock in the lm_notify handler. The simplest fix is to just declare a new per-nfsd_net spinlock to protect the new CB_NOTIFY_LOCK structures. Signed-off-by: Jeff Layton Signed-off-by: J. Bruce Fields --- fs/nfsd/netns.h | 5 +++++ fs/nfsd/nfs4state.c | 28 +++++++++++++++------------- 2 files changed, 20 insertions(+), 13 deletions(-) diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index b10d557f9c9e..ee36efd5aece 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -84,6 +84,8 @@ struct nfsd_net { struct list_head client_lru; struct list_head close_lru; struct list_head del_recall_lru; + + /* protected by blocked_locks_lock */ struct list_head blocked_locks_lru; struct delayed_work laundromat_work; @@ -91,6 +93,9 @@ struct nfsd_net { /* client_lock protects the client lru list and session hash table */ spinlock_t client_lock; + /* protects blocked_locks_lru */ + spinlock_t blocked_locks_lock; + struct file *rec_file; bool in_grace; const struct nfsd4_client_tracking_ops *client_tracking_ops; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 9752beb78659..95474196a17e 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -217,7 +217,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, { struct nfsd4_blocked_lock *cur, *found = NULL; - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); list_for_each_entry(cur, &lo->lo_blocked, nbl_list) { if (fh_match(fh, &cur->nbl_fh)) { list_del_init(&cur->nbl_list); @@ -226,7 +226,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh, break; } } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); if (found) posix_unblock_lock(&found->nbl_lock); return found; @@ -4665,7 +4665,7 @@ nfs4_laundromat(struct nfsd_net *nn) * indefinitely once the lock does become free. */ BUG_ON(!list_empty(&reaplist)); - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); while (!list_empty(&nn->blocked_locks_lru)) { nbl = list_first_entry(&nn->blocked_locks_lru, struct nfsd4_blocked_lock, nbl_lru); @@ -4678,7 +4678,7 @@ nfs4_laundromat(struct nfsd_net *nn) list_move(&nbl->nbl_lru, &reaplist); list_del_init(&nbl->nbl_list); } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); while (!list_empty(&reaplist)) { nbl = list_first_entry(&nn->blocked_locks_lru, @@ -5439,13 +5439,13 @@ nfsd4_lm_notify(struct file_lock *fl) bool queue = false; /* An empty list means that something else is going to be using it */ - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); if (!list_empty(&nbl->nbl_list)) { list_del_init(&nbl->nbl_list); list_del_init(&nbl->nbl_lru); queue = true; } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); if (queue) nfsd4_run_cb(&nbl->nbl_cb); @@ -5868,10 +5868,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, if (fl_flags & FL_SLEEP) { nbl->nbl_time = jiffies; - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked); list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru); - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); } err = vfs_lock_file(filp, F_SETLK, file_lock, conflock); @@ -5900,10 +5900,10 @@ out: if (nbl) { /* dequeue it if we queued it before */ if (fl_flags & FL_SLEEP) { - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); list_del_init(&nbl->nbl_list); list_del_init(&nbl->nbl_lru); - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); } free_blocked_lock(nbl); } @@ -6943,9 +6943,11 @@ static int nfs4_state_create_net(struct net *net) INIT_LIST_HEAD(&nn->client_lru); INIT_LIST_HEAD(&nn->close_lru); INIT_LIST_HEAD(&nn->del_recall_lru); - INIT_LIST_HEAD(&nn->blocked_locks_lru); spin_lock_init(&nn->client_lock); + spin_lock_init(&nn->blocked_locks_lock); + INIT_LIST_HEAD(&nn->blocked_locks_lru); + INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main); get_net(net); @@ -7063,14 +7065,14 @@ nfs4_state_shutdown_net(struct net *net) } BUG_ON(!list_empty(&reaplist)); - spin_lock(&nn->client_lock); + spin_lock(&nn->blocked_locks_lock); while (!list_empty(&nn->blocked_locks_lru)) { nbl = list_first_entry(&nn->blocked_locks_lru, struct nfsd4_blocked_lock, nbl_lru); list_move(&nbl->nbl_lru, &reaplist); list_del_init(&nbl->nbl_list); } - spin_unlock(&nn->client_lock); + spin_unlock(&nn->blocked_locks_lock); while (!list_empty(&reaplist)) { nbl = list_first_entry(&nn->blocked_locks_lru, -- 2.20.1