1 files changed, 60 insertions, 36 deletions

diff --git a/fs/fs_pin.c b/fs/fs_pin.c
index 9368236ca100..b06c98796afb 100644
--- a/fs/fs_pin.c
+++ b/fs/fs_pin.c
@@ -1,78 +1,102 @@
 #include <linux/fs.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
-#include <linux/fs_pin.h>
 #include "internal.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);
+	spin_lock_irq(&pin->wait.lock);
+	pin->done = 1;
+	wake_up_locked(&pin->wait);
+	spin_unlock_irq(&pin->wait.lock);
 }
 
-void pin_insert(struct fs_pin *pin, struct vfsmount *m)
+void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
 {
 	spin_lock(&pin_lock);
-	hlist_add_head(&pin->s_list, &m->mnt_sb->s_pins);
+	if (p)
+		hlist_add_head(&pin->s_list, p);
 	hlist_add_head(&pin->m_list, &real_mount(m)->mnt_pins);
 	spin_unlock(&pin_lock);
 }
 
+void pin_insert(struct fs_pin *pin, struct vfsmount *m)
+{
+	pin_insert_group(pin, m, &m->mnt_sb->s_pins);
+}
+
+void pin_kill(struct fs_pin *p)
+{
+	wait_queue_t wait;
+
+	if (!p) {
+		rcu_read_unlock();
+		return;
+	}
+	init_wait(&wait);
+	spin_lock_irq(&p->wait.lock);
+	if (likely(!p->done)) {
+		p->done = -1;
+		spin_unlock_irq(&p->wait.lock);
+		rcu_read_unlock();
+		p->kill(p);
+		return;
+	}
+	if (p->done > 0) {
+		spin_unlock_irq(&p->wait.lock);
+		rcu_read_unlock();
+		return;
+	}
+	__add_wait_queue(&p->wait, &wait);
+	while (1) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		spin_unlock_irq(&p->wait.lock);
+		rcu_read_unlock();
+		schedule();
+		rcu_read_lock();
+		if (likely(list_empty(&wait.task_list)))
+			break;
+		/* OK, we know p couldn't have been freed yet */
+		spin_lock_irq(&p->wait.lock);
+		if (p->done > 0) {
+			spin_unlock_irq(&p->wait.lock);
+			break;
+		}
+	}
+	rcu_read_unlock();
+}
+
 void mnt_pin_kill(struct mount *m)
 {
 	while (1) {
 		struct hlist_node *p;
-		struct fs_pin *pin;
 		rcu_read_lock();
 		p = ACCESS_ONCE(m->mnt_pins.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);
+		pin_kill(hlist_entry(p, struct fs_pin, m_list));
 	}
 }
 
-void sb_pin_kill(struct super_block *sb)
+void group_pin_kill(struct hlist_head *p)
 {
 	while (1) {
-		struct hlist_node *p;
-		struct fs_pin *pin;
+		struct hlist_node *q;
 		rcu_read_lock();
-		p = ACCESS_ONCE(sb->s_pins.first);
-		if (!p) {
+		q = ACCESS_ONCE(p->first);
+		if (!q) {
 			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);
+		pin_kill(hlist_entry(q, struct fs_pin, s_list));
 	}
 }