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-rw-r--r--fs/fs_pin.c77
1 files changed, 77 insertions, 0 deletions
diff --git a/fs/fs_pin.c b/fs/fs_pin.c
new file mode 100644
index 000000000000..f3ce0b874a44
--- /dev/null
+++ b/fs/fs_pin.c
@@ -0,0 +1,77 @@
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/fs_pin.h>
+#include "mount.h"
+
+static void pin_free_rcu(struct rcu_head *head)
+{
+ kfree(container_of(head, struct fs_pin, rcu));
+}
+
+static DEFINE_SPINLOCK(pin_lock);
+
+void pin_put(struct fs_pin *p)
+{
+ if (atomic_long_dec_and_test(&p->count))
+ call_rcu(&p->rcu, pin_free_rcu);
+}
+
+void pin_remove(struct fs_pin *pin)
+{
+ spin_lock(&pin_lock);
+ hlist_del(&pin->m_list);
+ hlist_del(&pin->s_list);
+ spin_unlock(&pin_lock);
+}
+
+void pin_insert(struct fs_pin *pin, struct vfsmount *m)
+{
+ spin_lock(&pin_lock);
+ hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
+ hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
+ spin_unlock(&pin_lock);
+}
+
+void acct_auto_close_mnt(struct hlist_head *list)
+{
+ while (1) {
+ struct hlist_node *p;
+ struct fs_pin *pin;
+ rcu_read_lock();
+ p = ACCESS_ONCE(list->first);
+ if (!p) {
+ rcu_read_unlock();
+ break;
+ }
+ pin = hlist_entry(p, struct fs_pin, m_list);
+ if (!atomic_long_inc_not_zero(&pin->count)) {
+ rcu_read_unlock();
+ cpu_relax();
+ continue;
+ }
+ rcu_read_unlock();
+ pin->kill(pin);
+ }
+}
+
+void acct_auto_close(struct hlist_head *list)
+{
+ while (1) {
+ struct hlist_node *p;
+ struct fs_pin *pin;
+ rcu_read_lock();
+ p = ACCESS_ONCE(list->first);
+ if (!p) {
+ rcu_read_unlock();
+ break;
+ }
+ pin = hlist_entry(p, struct fs_pin, s_list);
+ if (!atomic_long_inc_not_zero(&pin->count)) {
+ rcu_read_unlock();
+ cpu_relax();
+ continue;
+ }
+ rcu_read_unlock();
+ pin->kill(pin);
+ }
+}