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

source code of linux/fs/fs_pin.c