new fs_pin killing logics

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/fs_pin.c b/fs/fs_pin.c
index 50ef7d2..0c77bdc 100644 (file)
--- a/fs/fs_pin.c
+++ b/fs/fs_pin.c
@@ -1,4 +1,5 @@
 #include <linux/fs.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/fs_pin.h>
 #include "internal.h"
@@ -12,6 +13,10 @@ void pin_remove(struct fs_pin *pin)
        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_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
@@ -28,19 +33,58 @@ 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);
-               pin->kill(pin);
+               pin_kill(hlist_entry(p, struct fs_pin, m_list));
        }
 }
 
@@ -48,14 +92,12 @@ void group_pin_kill(struct hlist_head *p)
 {
        while (1) {
                struct hlist_node *q;
-               struct fs_pin *pin;
                rcu_read_lock();
                q = ACCESS_ONCE(p->first);
                if (!q) {
                        rcu_read_unlock();
                        break;
                }
-               pin = hlist_entry(q, struct fs_pin, s_list);
-               pin->kill(pin);
+               pin_kill(hlist_entry(q, struct fs_pin, s_list));
        }
 }

diff --git a/include/linux/fs_pin.h b/include/linux/fs_pin.h
index 2be38d1..9dc4e03 100644 (file)
--- a/include/linux/fs_pin.h
+++ b/include/linux/fs_pin.h
@@ -1,11 +1,22 @@
-#include <linux/fs.h>
+#include <linux/wait.h>
 
 struct fs_pin {
+       wait_queue_head_t       wait;
+       int                     done;
        struct hlist_node       s_list;
        struct hlist_node       m_list;
        void (*kill)(struct fs_pin *);
 };
 
+struct vfsmount;
+
+static inline void init_fs_pin(struct fs_pin *p, void (*kill)(struct fs_pin *))
+{
+       init_waitqueue_head(&p->wait);
+       p->kill = kill;
+}
+
 void pin_remove(struct fs_pin *);
 void pin_insert_group(struct fs_pin *, struct vfsmount *, struct hlist_head *);
 void pin_insert(struct fs_pin *, struct vfsmount *);
+void pin_kill(struct fs_pin *);

diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h
index b9cf6c5..918b117 100644 (file)
--- a/include/linux/pid_namespace.h
+++ b/include/linux/pid_namespace.h
@@ -19,7 +19,7 @@ struct pidmap {
 #define BITS_PER_PAGE_MASK     (BITS_PER_PAGE-1)
 #define PIDMAP_ENTRIES         ((PID_MAX_LIMIT+BITS_PER_PAGE-1)/BITS_PER_PAGE)
 
-struct bsd_acct_struct;
+struct fs_pin;
 
 struct pid_namespace {
        struct kref kref;
@@ -37,7 +37,7 @@ struct pid_namespace {
        struct dentry *proc_thread_self;
 #endif
 #ifdef CONFIG_BSD_PROCESS_ACCT
-       struct bsd_acct_struct *bacct;
+       struct fs_pin *bacct;
 #endif
        struct user_namespace *user_ns;
        struct work_struct proc_work;

diff --cc kernel/acct.c
Simple merge