diff options
| -rw-r--r-- | fs/kernfs/file.c | 47 | ||||
| -rw-r--r-- | include/linux/kernfs.h | 2 |
2 files changed, 28 insertions, 21 deletions
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index bb933221b4ba..baff4b1d40c7 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -25,16 +25,18 @@ struct kernfs_open_node { struct list_head files; /* goes through kernfs_open_file.list */ }; -/** - * attribute_to_node - get kernfs_node object corresponding to a kernfs attribute - * @ptr: &struct kernfs_elem_attr - * @type: struct kernfs_node - * @member: name of member (i.e attr) +/* + * kernfs_notify() may be called from any context and bounces notifications + * through a work item. To minimize space overhead in kernfs_node, the + * pending queue is implemented as a singly linked list of kernfs_nodes. + * The list is terminated with the self pointer so that whether a + * kernfs_node is on the list or not can be determined by testing the next + * pointer for NULL. */ -#define attribute_to_node(ptr, type, member) \ - container_of(ptr, type, member) +#define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list) -static LLIST_HEAD(kernfs_notify_list); +static DEFINE_SPINLOCK(kernfs_notify_lock); +static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL; static inline struct mutex *kernfs_open_file_mutex_ptr(struct kernfs_node *kn) { @@ -909,16 +911,18 @@ static void kernfs_notify_workfn(struct work_struct *work) struct kernfs_node *kn; struct kernfs_super_info *info; struct kernfs_root *root; - struct llist_node *free; - struct kernfs_elem_attr *attr; repeat: /* pop one off the notify_list */ - free = llist_del_first(&kernfs_notify_list); - if (free == NULL) + spin_lock_irq(&kernfs_notify_lock); + kn = kernfs_notify_list; + if (kn == KERNFS_NOTIFY_EOL) { + spin_unlock_irq(&kernfs_notify_lock); return; + } + kernfs_notify_list = kn->attr.notify_next; + kn->attr.notify_next = NULL; + spin_unlock_irq(&kernfs_notify_lock); - attr = llist_entry(free, struct kernfs_elem_attr, notify_next); - kn = attribute_to_node(attr, struct kernfs_node, attr); root = kernfs_root(kn); /* kick fsnotify */ down_write(&root->kernfs_rwsem); @@ -974,14 +978,12 @@ repeat: void kernfs_notify(struct kernfs_node *kn) { static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn); + unsigned long flags; struct kernfs_open_node *on; if (WARN_ON(kernfs_type(kn) != KERNFS_FILE)) return; - /* Because we are using llist for kernfs_notify_list */ - WARN_ON_ONCE(in_nmi()); - /* kick poll immediately */ rcu_read_lock(); on = rcu_dereference(kn->attr.open); @@ -992,9 +994,14 @@ void kernfs_notify(struct kernfs_node *kn) rcu_read_unlock(); /* schedule work to kick fsnotify */ - kernfs_get(kn); - llist_add(&kn->attr.notify_next, &kernfs_notify_list); - schedule_work(&kernfs_notify_work); + spin_lock_irqsave(&kernfs_notify_lock, flags); + if (!kn->attr.notify_next) { + kernfs_get(kn); + kn->attr.notify_next = kernfs_notify_list; + kernfs_notify_list = kn; + schedule_work(&kernfs_notify_work); + } + spin_unlock_irqrestore(&kernfs_notify_lock, flags); } EXPORT_SYMBOL_GPL(kernfs_notify); diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h index 13e703f615f7..367044d7708c 100644 --- a/include/linux/kernfs.h +++ b/include/linux/kernfs.h @@ -173,7 +173,7 @@ struct kernfs_elem_attr { const struct kernfs_ops *ops; struct kernfs_open_node __rcu *open; loff_t size; - struct llist_node notify_next; /* for kernfs_notify() */ + struct kernfs_node *notify_next; /* for kernfs_notify() */ }; /* |