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}
103