#include <linux/fs.h> #include <linux/slab.h> #include <linux/fs_pin.h> #include "internal.h" #include "mount.h" static void pin_free_rcu(struct rcu_head *head) { kfree(container_of(head, struct fs_pin, rcu)); } static DEFINE_SPINLOCK(pin_lock); void pin_put(struct fs_pin *p) { if (atomic_long_dec_and_test(&p->count)) call_rcu(&p->rcu, pin_free_rcu); } void pin_remove(struct fs_pin *pin) { spin_lock(&pin_lock); hlist_del(&pin->m_list); hlist_del(&pin->s_list); spin_unlock(&pin_lock); } void pin_insert(struct fs_pin *pin, struct vfsmount *m) { spin_lock(&pin_lock); hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins); hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins); spin_unlock(&pin_lock); } void mnt_pin_kill(struct mount *m) { while (1) { struct hlist_node *p; struct fs_pin *pin; rcu_read_lock(); p = ACCESS_ONCE(m->mnt_pins.first); if (!p) { rcu_read_unlock(); break; } pin = hlist_entry(p, struct fs_pin, m_list); if (!atomic_long_inc_not_zero(&pin->count)) { rcu_read_unlock(); cpu_relax(); continue; } rcu_read_unlock(); pin->kill(pin); } } void sb_pin_kill(struct super_block *sb) { while (1) { struct hlist_node *p; struct fs_pin *pin; rcu_read_lock(); p = ACCESS_ONCE(sb->s_pins.first); if (!p) { rcu_read_unlock(); break; } pin = hlist_entry(p, struct fs_pin, s_list); if (!atomic_long_inc_not_zero(&pin->count)) { rcu_read_unlock(); cpu_relax(); continue; } rcu_read_unlock(); pin->kill(pin); } }