fsnotify implements its own call_srcu() by:
        dedicated thread + synchronize_srcu()

But srcu provides call_srcu() now, so we should convert them to use
existed call_srcu() and remove the thread.

Signed-off-by: Lai Jiangshan <la...@cn.fujitsu.com>
Cc: Eric Paris <epa...@parisplace.org>
---
 fs/notify/mark.c                 |   59 ++++++-------------------------------
 include/linux/fsnotify_backend.h |    2 +-
 2 files changed, 11 insertions(+), 50 deletions(-)

diff --git a/fs/notify/mark.c b/fs/notify/mark.c
index aeededc..af5f0e1 100644
--- a/fs/notify/mark.c
+++ b/fs/notify/mark.c
@@ -98,9 +98,6 @@
 #include "fsnotify.h"
 
 DEFINE_SRCU(fsnotify_mark_srcu);
-static DEFINE_SPINLOCK(destroy_lock);
-static LIST_HEAD(destroy_list);
-static DECLARE_WAIT_QUEUE_HEAD(destroy_waitq);
 
 void fsnotify_get_mark(struct fsnotify_mark *mark)
 {
@@ -116,6 +113,14 @@ void fsnotify_put_mark(struct fsnotify_mark *mark)
        }
 }
 
+static void fsnotify_destroy_mark_rcu(struct rcu_head *rcu)
+{
+       struct fsnotify_mark *mark;
+
+       mark = container_of(rcu, struct fsnotify_mark, rcu);
+       fsnotify_put_mark(mark);
+}
+
 /*
  * Any time a mark is getting freed we end up here.
  * The caller had better be holding a reference to this mark so we don't 
actually
@@ -155,10 +160,7 @@ void fsnotify_destroy_mark_locked(struct fsnotify_mark 
*mark,
        /* release lock temporarily */
        mutex_unlock(&group->mark_mutex);
 
-       spin_lock(&destroy_lock);
-       list_add(&mark->destroy_list, &destroy_list);
-       spin_unlock(&destroy_lock);
-       wake_up(&destroy_waitq);
+       call_srcu(&fsnotify_mark_srcu, &mark->rcu, fsnotify_destroy_mark_rcu);
        /*
         * We don't necessarily have a ref on mark from caller so the above 
destroy
         * may have actually freed it, unless this group provides a 
'freeing_mark'
@@ -273,11 +275,7 @@ err:
        atomic_dec(&group->num_marks);
 
        spin_unlock(&mark->lock);
-
-       spin_lock(&destroy_lock);
-       list_add(&mark->destroy_list, &destroy_list);
-       spin_unlock(&destroy_lock);
-       wake_up(&destroy_waitq);
+       call_srcu(&fsnotify_mark_srcu, &mark->rcu, fsnotify_destroy_mark_rcu);
 
        return ret;
 }
@@ -342,40 +340,3 @@ void fsnotify_init_mark(struct fsnotify_mark *mark,
        atomic_set(&mark->refcnt, 1);
        mark->free_mark = free_mark;
 }
-
-static int fsnotify_mark_destroy(void *ignored)
-{
-       struct fsnotify_mark *mark, *next;
-       LIST_HEAD(private_destroy_list);
-
-       for (;;) {
-               spin_lock(&destroy_lock);
-               /* exchange the list head */
-               list_replace_init(&destroy_list, &private_destroy_list);
-               spin_unlock(&destroy_lock);
-
-               synchronize_srcu(&fsnotify_mark_srcu);
-
-               list_for_each_entry_safe(mark, next, &private_destroy_list, 
destroy_list) {
-                       list_del_init(&mark->destroy_list);
-                       fsnotify_put_mark(mark);
-               }
-
-               wait_event_interruptible(destroy_waitq, 
!list_empty(&destroy_list));
-       }
-
-       return 0;
-}
-
-static int __init fsnotify_mark_init(void)
-{
-       struct task_struct *thread;
-
-       thread = kthread_run(fsnotify_mark_destroy, NULL,
-                            "fsnotify_mark");
-       if (IS_ERR(thread))
-               panic("unable to start fsnotify mark destruction thread.");
-
-       return 0;
-}
-device_initcall(fsnotify_mark_init);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index d5b0910..3d435eb 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -296,7 +296,7 @@ struct fsnotify_mark {
 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
 #define FSNOTIFY_MARK_FLAG_ALIVE               0x10
        unsigned int flags;             /* vfsmount or inode mark? */
-       struct list_head destroy_list;
+       struct rcu_head rcu;
        void (*free_mark)(struct fsnotify_mark *mark); /* called on final 
put+free */
 };
 
-- 
1.7.4.4

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