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Linux/fs/fs_pin.c

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

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