fs/fs_pin.c

   1 #include <linux/fs.h>
   2 #include <linux/slab.h>
   3 #include <linux/fs_pin.h>
   4 #include "mount.h"
   5
   6 static void pin_free_rcu(struct rcu_head *head)
   7 {
   8         kfree(container_of(head, struct fs_pin, rcu));
   9 }
  10
  11 static DEFINE_SPINLOCK(pin_lock);
  12
  13 void pin_put(struct fs_pin *p)
  14 {
  15         if (atomic_long_dec_and_test(&p->count))
  16                 call_rcu(&p->rcu, pin_free_rcu);
  17 }
  18
  19 void pin_remove(struct fs_pin *pin)
  20 {
  21         spin_lock(&pin_lock);
  22         hlist_del(&pin->m_list);
  23         hlist_del(&pin->s_list);
  24         spin_unlock(&pin_lock);
  25 }
  26
  27 void pin_insert(struct fs_pin *pin, struct vfsmount *m)
  28 {
  29         spin_lock(&pin_lock);
  30         hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
  31         hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
  32         spin_unlock(&pin_lock);
  33 }
  34
  35 void acct_auto_close_mnt(struct hlist_head *list)
  36 {
  37         while (1) {
  38                 struct hlist_node *p;
  39                 struct fs_pin *pin;
  40                 rcu_read_lock();
  41                 p = ACCESS_ONCE(list->first);
  42                 if (!p) {
  43                         rcu_read_unlock();
  44                         break;
  45                 }
  46                 pin = hlist_entry(p, struct fs_pin, m_list);
  47                 if (!atomic_long_inc_not_zero(&pin->count)) {
  48                         rcu_read_unlock();
  49                         cpu_relax();
  50                         continue;
  51                 }
  52                 rcu_read_unlock();
  53                 pin->kill(pin);
  54         }
  55 }
  56
  57 void acct_auto_close(struct hlist_head *list)
  58 {
  59         while (1) {
  60                 struct hlist_node *p;
  61                 struct fs_pin *pin;
  62                 rcu_read_lock();
  63                 p = ACCESS_ONCE(list->first);
  64                 if (!p) {
  65                         rcu_read_unlock();
  66                         break;
  67                 }
  68                 pin = hlist_entry(p, struct fs_pin, s_list);
  69                 if (!atomic_long_inc_not_zero(&pin->count)) {
  70                         rcu_read_unlock();
  71                         cpu_relax();
  72                         continue;
  73                 }
  74                 rcu_read_unlock();
  75                 pin->kill(pin);
  76         }
  77 }