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_entry_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.entry)))
  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 }