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 void pin_free_rcu(struct rcu_head *head)
   8 {
   9         kfree(container_of(head, struct fs_pin, rcu));
  10 }
  11
  12 static DEFINE_SPINLOCK(pin_lock);
  13
  14 void pin_put(struct fs_pin *p)
  15 {
  16         if (atomic_long_dec_and_test(&p->count))
  17                 call_rcu(&p->rcu, pin_free_rcu);
  18 }
  19
  20 void pin_remove(struct fs_pin *pin)
  21 {
  22         spin_lock(&pin_lock);
  23         hlist_del(&pin->m_list);
  24         hlist_del(&pin->s_list);
  25         spin_unlock(&pin_lock);
  26 }
  27
  28 void pin_insert(struct fs_pin *pin, struct vfsmount *m)
  29 {
  30         spin_lock(&pin_lock);
  31         hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
  32         hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
  33         spin_unlock(&pin_lock);
  34 }
  35
  36 void mnt_pin_kill(struct mount *m)
  37 {
  38         while (1) {
  39                 struct hlist_node *p;
  40                 struct fs_pin *pin;
  41                 rcu_read_lock();
  42                 p = ACCESS_ONCE(m->mnt_pins.first);
  43                 if (!p) {
  44                         rcu_read_unlock();
  45                         break;
  46                 }
  47                 pin = hlist_entry(p, struct fs_pin, m_list);
  48                 if (!atomic_long_inc_not_zero(&pin->count)) {
  49                         rcu_read_unlock();
  50                         cpu_relax();
  51                         continue;
  52                 }
  53                 rcu_read_unlock();
  54                 pin->kill(pin);
  55         }
  56 }
  57
  58 void sb_pin_kill(struct super_block *sb)
  59 {
  60         while (1) {
  61                 struct hlist_node *p;
  62                 struct fs_pin *pin;
  63                 rcu_read_lock();
  64                 p = ACCESS_ONCE(sb->s_pins.first);
  65                 if (!p) {
  66                         rcu_read_unlock();
  67                         break;
  68                 }
  69                 pin = hlist_entry(p, struct fs_pin, s_list);
  70                 if (!atomic_long_inc_not_zero(&pin->count)) {
  71                         rcu_read_unlock();
  72                         cpu_relax();
  73                         continue;
  74                 }
  75                 rcu_read_unlock();
  76                 pin->kill(pin);
  77         }
  78 }