1// SPDX-License-Identifier: GPL-2.0
2#include <linux/fs.h>
3#include <linux/sched.h>
4#include <linux/slab.h>
5#include "internal.h"
6#include "mount.h"
7
8static DEFINE_SPINLOCK(pin_lock);
9
10void pin_remove(struct fs_pin *pin)
11{
12 spin_lock(&pin_lock);
13 hlist_del_init(&pin->m_list);
14 hlist_del_init(&pin->s_list);
15 spin_unlock(&pin_lock);
16 spin_lock_irq(&pin->wait.lock);
17 pin->done = 1;
18 wake_up_locked(&pin->wait);
19 spin_unlock_irq(&pin->wait.lock);
20}
21
22void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
23{
24 spin_lock(&pin_lock);
25 if (p)
26 hlist_add_head(&pin->s_list, p);
27 hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
28 spin_unlock(&pin_lock);
29}
30
31void pin_insert(struct fs_pin *pin, struct vfsmount *m)
32{
33 pin_insert_group(pin, m, &m->mnt_sb->s_pins);
34}
35
36void pin_kill(struct fs_pin *p)
37{
38 wait_queue_entry_t wait;
39
40 if (!p) {
41 rcu_read_unlock();
42 return;
43 }
44 init_wait(&wait);
45 spin_lock_irq(&p->wait.lock);
46 if (likely(!p->done)) {
47 p->done = -1;
48 spin_unlock_irq(&p->wait.lock);
49 rcu_read_unlock();
50 p->kill(p);
51 return;
52 }
53 if (p->done > 0) {
54 spin_unlock_irq(&p->wait.lock);
55 rcu_read_unlock();
56 return;
57 }
58 __add_wait_queue(&p->wait, &wait);
59 while (1) {
60 set_current_state(TASK_UNINTERRUPTIBLE);
61 spin_unlock_irq(&p->wait.lock);
62 rcu_read_unlock();
63 schedule();
64 rcu_read_lock();
65 if (likely(list_empty(&wait.entry)))
66 break;
67 /* OK, we know p couldn't have been freed yet */
68 spin_lock_irq(&p->wait.lock);
69 if (p->done > 0) {
70 spin_unlock_irq(&p->wait.lock);
71 break;
72 }
73 }
74 rcu_read_unlock();
75}
76
77void mnt_pin_kill(struct mount *m)
78{
79 while (1) {
80 struct hlist_node *p;
81 rcu_read_lock();
82 p = READ_ONCE(m->mnt_pins.first);
83 if (!p) {
84 rcu_read_unlock();
85 break;
86 }
87 pin_kill(hlist_entry(p, struct fs_pin, m_list));
88 }
89}
90
91void group_pin_kill(struct hlist_head *p)
92{
93 while (1) {
94 struct hlist_node *q;
95 rcu_read_lock();
96 q = READ_ONCE(p->first);
97 if (!q) {
98 rcu_read_unlock();
99 break;
100 }
101 pin_kill(hlist_entry(q, struct fs_pin, s_list));
102 }
103}
104