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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 | } |