path: root/fs/fs_pin.c (plain)
blob: 611b5408f6ec48f84d8cd04a4ea5ec1911a968ba

1	#include <linux/fs.h>
2	#include <linux/sched.h>
3	#include <linux/slab.h>
4	#include "internal.h"
5	#include "mount.h"
6
7	static DEFINE_SPINLOCK(pin_lock);
8
9	void 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
21	void 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
30	void pin_insert(struct fs_pin *pin, struct vfsmount *m)
31	{
32	pin_insert_group(pin, m, &m->mnt_sb->s_pins);
33	}
34
35	void 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
76	void 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
90	void 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