diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index da5a44c31acb..1ea2bfd51825 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -55,6 +55,17 @@ /* We only care about NFSD_MAY_READ/WRITE for this cache */ #define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE|NFSD_MAY_LOCALIO) +/* If the shrinker runs between calls to list_lru_walk_node() in + * nfsd_file_gc(), the "remaining" count will be wrong. This could + * result in premature freeing of some files. This may not matter much + * but is easy to fix with this spinlock which temporarily disables + * the shrinker. + * + * It also serializes callers of nfsd_file_dispose_list_delayed() + * against per-net shutdown. + */ +static DEFINE_SPINLOCK(nfsd_gc_lock); + static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits); static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions); static DEFINE_PER_CPU(unsigned long, nfsd_file_allocations); @@ -423,10 +434,16 @@ nfsd_file_dispose_list(struct list_head *dispose) * Transfers each file to the dispose list in its nfsd_net and wakes an nfsd * thread to do the actual close. This keeps the cost of fput() in the nfsd * threads rather than in the shrinker or GC worker. + * + * All callers must hold nfsd_gc_lock, so that nfsd_file_cache_shutdown_net() + * can synchronize against them before draining the per-net dispose list. + * This guarantees nf_net is still live when we call net_generic(). */ static void nfsd_file_dispose_list_delayed(struct list_head *dispose) { + lockdep_assert_held(&nfsd_gc_lock); + while (!list_empty(dispose)) { struct nfsd_file *nf = list_first_entry(dispose, struct nfsd_file, nf_gc); @@ -557,13 +574,6 @@ nfsd_file_gc_cb(struct list_head *item, struct list_lru_one *lru, return nfsd_file_lru_cb(item, lru, arg); } -/* If the shrinker runs between calls to list_lru_walk_node() in - * nfsd_file_gc(), the "remaining" count will be wrong. This could - * result in premature freeing of some files. This may not matter much - * but is easy to fix with this spinlock which temporarily disables - * the shrinker. - */ -static DEFINE_SPINLOCK(nfsd_gc_lock); static void nfsd_file_gc(void) { @@ -586,9 +596,9 @@ nfsd_file_gc(void) remaining = 0; } } + nfsd_file_dispose_list_delayed(&dispose); spin_unlock(&nfsd_gc_lock); trace_nfsd_file_gc_removed(ret, list_lru_count(&nfsd_file_lru)); - nfsd_file_dispose_list_delayed(&dispose); } static void @@ -616,9 +626,9 @@ nfsd_file_lru_scan(struct shrinker *s, struct shrink_control *sc) ret = list_lru_shrink_walk(&nfsd_file_lru, sc, nfsd_file_lru_cb, &dispose); + nfsd_file_dispose_list_delayed(&dispose); spin_unlock(&nfsd_gc_lock); trace_nfsd_file_shrinker_removed(ret, list_lru_count(&nfsd_file_lru)); - nfsd_file_dispose_list_delayed(&dispose); return ret; } @@ -704,8 +714,10 @@ nfsd_file_close_inode(struct inode *inode) { LIST_HEAD(dispose); + spin_lock(&nfsd_gc_lock); nfsd_file_queue_for_close(inode, &dispose); nfsd_file_dispose_list_delayed(&dispose); + spin_unlock(&nfsd_gc_lock); } /** @@ -974,6 +986,14 @@ nfsd_file_cache_shutdown_net(struct net *net) struct nfsd_net *nn = net_generic(net, nfsd_net_id); nfsd_file_cache_purge(net); + /* + * Ensure any in-progress shrinker, GC, or fsnotify/lease callback + * (all of which hold nfsd_gc_lock while calling + * nfsd_file_dispose_list_delayed()) has fully completed before + * draining the per-net dispose list. + */ + spin_lock(&nfsd_gc_lock); + spin_unlock(&nfsd_gc_lock); nfsd_file_dispose_list(&nn->fcache_dispose_list); }