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SubjectRe: [PATCH 7/9] fsnotify: use existed call_srcu()
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Hi, Eric Paris

Could you review this patch?

Thanks,
Lai

On 03/16/2013 12:50 AM, Lai Jiangshan wrote:
> 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 <laijs@cn.fujitsu.com>
> Cc: Eric Paris <eparis@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 */
> };
>



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