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
pin_remove(struct fs_pin * pin)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
pin_insert_group(struct fs_pin * pin,struct vfsmount * m,struct hlist_head * p)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
pin_insert(struct fs_pin * pin,struct vfsmount * m)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
pin_kill(struct fs_pin * p)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
mnt_pin_kill(struct mount * m)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
group_pin_kill(struct hlist_head * p)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