fs/fs_pin.c

   1 #include <linux/fs.h>
   2 #include <linux/slab.h>
   3 #include <linux/fs_pin.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(&pin->m_list);
  13         hlist_del(&pin->s_list);
  14         spin_unlock(&pin_lock);
  15 }
  16
  17 void pin_insert(struct fs_pin *pin, struct vfsmount *m)
  18 {
  19         spin_lock(&pin_lock);
  20         hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
  21         hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
  22         spin_unlock(&pin_lock);
  23 }
  24
  25 void mnt_pin_kill(struct mount *m)
  26 {
  27         while (1) {
  28                 struct hlist_node *p;
  29                 struct fs_pin *pin;
  30                 rcu_read_lock();
  31                 p = ACCESS_ONCE(m->mnt_pins.first);
  32                 if (!p) {
  33                         rcu_read_unlock();
  34                         break;
  35                 }
  36                 pin = hlist_entry(p, struct fs_pin, m_list);
  37                 if (!atomic_long_inc_not_zero(&pin->count)) {
  38                         rcu_read_unlock();
  39                         cpu_relax();
  40                         continue;
  41                 }
  42                 rcu_read_unlock();
  43                 pin->kill(pin);
  44         }
  45 }
  46
  47 void sb_pin_kill(struct super_block *sb)
  48 {
  49         while (1) {
  50                 struct hlist_node *p;
  51                 struct fs_pin *pin;
  52                 rcu_read_lock();
  53                 p = ACCESS_ONCE(sb->s_pins.first);
  54                 if (!p) {
  55                         rcu_read_unlock();
  56                         break;
  57                 }
  58                 pin = hlist_entry(p, struct fs_pin, s_list);
  59                 if (!atomic_long_inc_not_zero(&pin->count)) {
  60                         rcu_read_unlock();
  61                         cpu_relax();
  62                         continue;
  63                 }
  64                 rcu_read_unlock();
  65                 pin->kill(pin);
  66         }
  67 }