fs_pin.c
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// SPDX-License-Identifier: GPL-2.0
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include "internal.h"
#include "mount.h"
static DEFINE_SPINLOCK(pin_lock);
void pin_remove(struct fs_pin *pin)
{
spin_lock(&pin_lock);
hlist_del_init(&pin->m_list);
hlist_del_init(&pin->s_list);
spin_unlock(&pin_lock);
spin_lock_irq(&pin->wait.lock);
pin->done = 1;
wake_up_locked(&pin->wait);
spin_unlock_irq(&pin->wait.lock);
}
void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
{
spin_lock(&pin_lock);
if (p)
hlist_add_head(&pin->s_list, p);
hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
spin_unlock(&pin_lock);
}
void pin_insert(struct fs_pin *pin, struct vfsmount *m)
{
pin_insert_group(pin, m, &m->mnt_sb->s_pins);
}
void pin_kill(struct fs_pin *p)
{
wait_queue_entry_t wait;
if (!p) {
rcu_read_unlock();
return;
}
init_wait(&wait);
spin_lock_irq(&p->wait.lock);
if (likely(!p->done)) {
p->done = -1;
spin_unlock_irq(&p->wait.lock);
rcu_read_unlock();
p->kill(p);
return;
}
if (p->done > 0) {
spin_unlock_irq(&p->wait.lock);
rcu_read_unlock();
return;
}
__add_wait_queue(&p->wait, &wait);
while (1) {
set_current_state(TASK_UNINTERRUPTIBLE);
spin_unlock_irq(&p->wait.lock);
rcu_read_unlock();
schedule();
rcu_read_lock();
if (likely(list_empty(&wait.entry)))
break;
/* OK, we know p couldn't have been freed yet */
spin_lock_irq(&p->wait.lock);
if (p->done > 0) {
spin_unlock_irq(&p->wait.lock);
break;
}
}
rcu_read_unlock();
}
void mnt_pin_kill(struct mount *m)
{
while (1) {
struct hlist_node *p;
rcu_read_lock();
p = ACCESS_ONCE(m->mnt_pins.first);
if (!p) {
rcu_read_unlock();
break;
}
pin_kill(hlist_entry(p, struct fs_pin, m_list));
}
}
void group_pin_kill(struct hlist_head *p)
{
while (1) {
struct hlist_node *q;
rcu_read_lock();
q = ACCESS_ONCE(p->first);
if (!q) {
rcu_read_unlock();
break;
}
pin_kill(hlist_entry(q, struct fs_pin, s_list));
}
}