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
8 static DEFINE_SPINLOCK(pin_lock);
9
10 void 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
22 void pin_insert(struct fs_pin *pin, struct vfsmount *m)
23 {
24 spin_lock(&pin_lock);
25 hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
26 hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
27 spin_unlock(&pin_lock);
28 }
29
30 void 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(&p->wait.lock);
40 if (likely(!p->done)) {
41 p->done = -1;
42 spin_unlock_irq(&p->wait.lock);
43 rcu_read_unlock();
44 p->kill(p);
45 return;
46 }
47 if (p->done > 0) {
48 spin_unlock_irq(&p->wait.lock);
49 rcu_read_unlock();
50 return;
51 }
52 __add_wait_queue(&p->wait, &wait);
53 while (1) {
54 set_current_state(TASK_UNINTERRUPTIBLE);
55 spin_unlock_irq(&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(&p->wait.lock);
63 if (p->done > 0) {
64 spin_unlock_irq(&p->wait.lock);
65 break;
66 }
67 }
68 rcu_read_unlock();
69 }
70
71 void 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
85 void 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
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