1#include <linux/fs.h>
  2#include <linux/sched.h>
  3#include <linux/slab.h>
  4#include "internal.h"
  5#include "mount.h"
  6
  7static DEFINE_SPINLOCK(pin_lock);
  8
  9void pin_remove(struct fs_pin *pin)
 10{
 11	spin_lock(&pin_lock);
 12	hlist_del_init(&pin->m_list);
 13	hlist_del_init(&pin->s_list);
 14	spin_unlock(&pin_lock);
 15	spin_lock_irq(&pin->wait.lock);
 16	pin->done = 1;
 17	wake_up_locked(&pin->wait);
 18	spin_unlock_irq(&pin->wait.lock);
 19}
 20
 21void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
 22{
 23	spin_lock(&pin_lock);
 24	if (p)
 25		hlist_add_head(&pin->s_list, p);
 26	hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
 27	spin_unlock(&pin_lock);
 28}
 29
 30void pin_insert(struct fs_pin *pin, struct vfsmount *m)
 31{
 32	pin_insert_group(pin, m, &m->mnt_sb->s_pins);
 33}
 34
 35void pin_kill(struct fs_pin *p)
 36{
 37	wait_queue_t wait;
 38
 39	if (!p) {
 40		rcu_read_unlock();
 41		return;
 42	}
 43	init_wait(&wait);
 44	spin_lock_irq(&p->wait.lock);
 45	if (likely(!p->done)) {
 46		p->done = -1;
 47		spin_unlock_irq(&p->wait.lock);
 48		rcu_read_unlock();
 49		p->kill(p);
 50		return;
 51	}
 52	if (p->done > 0) {
 53		spin_unlock_irq(&p->wait.lock);
 54		rcu_read_unlock();
 55		return;
 56	}
 57	__add_wait_queue(&p->wait, &wait);
 58	while (1) {
 59		set_current_state(TASK_UNINTERRUPTIBLE);
 60		spin_unlock_irq(&p->wait.lock);
 61		rcu_read_unlock();
 62		schedule();
 63		rcu_read_lock();
 64		if (likely(list_empty(&wait.task_list)))
 65			break;
 66		/* OK, we know p couldn't have been freed yet */
 67		spin_lock_irq(&p->wait.lock);
 68		if (p->done > 0) {
 69			spin_unlock_irq(&p->wait.lock);
 70			break;
 71		}
 72	}
 73	rcu_read_unlock();
 74}
 75
 76void mnt_pin_kill(struct mount *m)
 77{
 78	while (1) {
 79		struct hlist_node *p;
 80		rcu_read_lock();
 81		p = ACCESS_ONCE(m->mnt_pins.first);
 82		if (!p) {
 83			rcu_read_unlock();
 84			break;
 85		}
 86		pin_kill(hlist_entry(p, struct fs_pin, m_list));
 87	}
 88}
 89
 90void group_pin_kill(struct hlist_head *p)
 91{
 92	while (1) {
 93		struct hlist_node *q;
 94		rcu_read_lock();
 95		q = ACCESS_ONCE(p->first);
 96		if (!q) {
 97			rcu_read_unlock();
 98			break;
 99		}
100		pin_kill(hlist_entry(q, struct fs_pin, s_list));
101	}
102}