[lustre-devel] [PATCH 16/28] lustre: portals_handle: use hlist for hash lists.

[Andreas Dilger <adilger@whamcloud.com>]

On Mar 3, 2019, at 23:31, NeilBrown <neilb@suse.com> wrote:
> 
> hlist_head/hlist_node is the preferred data structure
> for hash tables. Not only does it make the 'head' smaller,
> but is also provides hlist_unhashed() which can be used to
> check if an object is in the list.  This means that
> we don't need h_in any more.
> 
> Signed-off-by: NeilBrown <neilb@suse.com>

Reviewed-by: Andreas Dilger <adilger@whamcloud.com>

> ---
> .../staging/lustre/lustre/include/lustre_handles.h |    3 +--
> drivers/staging/lustre/lustre/ldlm/ldlm_lock.c     |    2 +-
> drivers/staging/lustre/lustre/obdclass/genops.c    |    4 ++--
> .../lustre/lustre/obdclass/lustre_handles.c        |   20 +++++++++-----------
> 4 files changed, 13 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/include/lustre_handles.h b/drivers/staging/lustre/lustre/include/lustre_handles.h
> index ebbbb01710e7..cc433f48d367 100644
> --- a/drivers/staging/lustre/lustre/include/lustre_handles.h
> +++ b/drivers/staging/lustre/lustre/include/lustre_handles.h
> @@ -58,7 +58,7 @@
>  * to compute the start of the structure based on the handle field.
>  */
> struct portals_handle {
> -	struct list_head		h_link;
> +	struct hlist_node		h_link;
> 	u64				h_cookie;
> 	char				*h_owner;
> 	refcount_t			h_ref;
> @@ -66,7 +66,6 @@ struct portals_handle {
> 	/* newly added fields to handle the RCU issue. -jxiong */
> 	struct rcu_head			h_rcu;
> 	spinlock_t			h_lock;
> -	unsigned int			h_in:1;
> };
> 
> /* handles.c */
> diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c
> index 56a2d1dcd663..5ac77238e5f2 100644
> --- a/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c
> +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_lock.c
> @@ -402,7 +402,7 @@ static struct ldlm_lock *ldlm_lock_new(struct ldlm_resource *resource)
> 
> 	lprocfs_counter_incr(ldlm_res_to_ns(resource)->ns_stats,
> 			     LDLM_NSS_LOCKS);
> -	INIT_LIST_HEAD(&lock->l_handle.h_link);
> +	INIT_HLIST_NODE(&lock->l_handle.h_link);
> 	class_handle_hash(&lock->l_handle, lock_handle_owner);
> 
> 	lu_ref_init(&lock->l_reference);
> diff --git a/drivers/staging/lustre/lustre/obdclass/genops.c b/drivers/staging/lustre/lustre/obdclass/genops.c
> index e0da46e7d355..562e8a9f35c9 100644
> --- a/drivers/staging/lustre/lustre/obdclass/genops.c
> +++ b/drivers/staging/lustre/lustre/obdclass/genops.c
> @@ -858,7 +858,7 @@ static struct obd_export *__class_new_export(struct obd_device *obd,
> 	spin_lock_init(&export->exp_uncommitted_replies_lock);
> 	INIT_LIST_HEAD(&export->exp_uncommitted_replies);
> 	INIT_LIST_HEAD(&export->exp_req_replay_queue);
> -	INIT_LIST_HEAD(&export->exp_handle.h_link);
> +	INIT_HLIST_NODE(&export->exp_handle.h_link);
> 	INIT_LIST_HEAD(&export->exp_hp_rpcs);
> 	class_handle_hash(&export->exp_handle, export_handle_owner);
> 	spin_lock_init(&export->exp_lock);
> @@ -1046,7 +1046,7 @@ struct obd_import *class_new_import(struct obd_device *obd)
> 	atomic_set(&imp->imp_replay_inflight, 0);
> 	atomic_set(&imp->imp_inval_count, 0);
> 	INIT_LIST_HEAD(&imp->imp_conn_list);
> -	INIT_LIST_HEAD(&imp->imp_handle.h_link);
> +	INIT_HLIST_NODE(&imp->imp_handle.h_link);
> 	class_handle_hash(&imp->imp_handle, import_handle_owner);
> 	init_imp_at(&imp->imp_at);
> 
> diff --git a/drivers/staging/lustre/lustre/obdclass/lustre_handles.c b/drivers/staging/lustre/lustre/obdclass/lustre_handles.c
> index 45e5eac47292..72de668c879b 100644
> --- a/drivers/staging/lustre/lustre/obdclass/lustre_handles.c
> +++ b/drivers/staging/lustre/lustre/obdclass/lustre_handles.c
> @@ -48,7 +48,7 @@ static spinlock_t handle_base_lock;
> 
> static struct handle_bucket {
> 	spinlock_t		lock;
> -	struct list_head	head;
> +	struct hlist_head	head;
> } *handle_hash;
> 
> #define HANDLE_HASH_SIZE (1 << 16)
> @@ -63,7 +63,7 @@ void class_handle_hash(struct portals_handle *h, char *owner)
> 	struct handle_bucket *bucket;
> 
> 	LASSERT(h);
> -	LASSERT(list_empty(&h->h_link));
> +	LASSERT(hlist_unhashed(&h->h_link));
> 
> 	/*
> 	 * This is fast, but simplistic cookie generation algorithm, it will
> @@ -89,8 +89,7 @@ void class_handle_hash(struct portals_handle *h, char *owner)
> 
> 	bucket = &handle_hash[h->h_cookie & HANDLE_HASH_MASK];
> 	spin_lock(&bucket->lock);
> -	list_add_rcu(&h->h_link, &bucket->head);
> -	h->h_in = 1;
> +	hlist_add_head_rcu(&h->h_link, &bucket->head);
> 	spin_unlock(&bucket->lock);
> 
> 	CDEBUG(D_INFO, "added object %p with handle %#llx to hash\n",
> @@ -100,7 +99,7 @@ EXPORT_SYMBOL(class_handle_hash);
> 
> static void class_handle_unhash_nolock(struct portals_handle *h)
> {
> -	if (list_empty(&h->h_link)) {
> +	if (hlist_unhashed(&h->h_link)) {
> 		CERROR("removing an already-removed handle (%#llx)\n",
> 		       h->h_cookie);
> 		return;
> @@ -110,13 +109,12 @@ static void class_handle_unhash_nolock(struct portals_handle *h)
> 	       h, h->h_cookie);
> 
> 	spin_lock(&h->h_lock);
> -	if (h->h_in == 0) {
> +	if (hlist_unhashed(&h->h_link)) {
> 		spin_unlock(&h->h_lock);
> 		return;
> 	}
> -	h->h_in = 0;
> +	hlist_del_init_rcu(&h->h_link);
> 	spin_unlock(&h->h_lock);
> -	list_del_rcu(&h->h_link);
> }
> 
> void class_handle_unhash(struct portals_handle *h)
> @@ -145,7 +143,7 @@ void *class_handle2object(u64 cookie, char *owner)
> 	bucket = handle_hash + (cookie & HANDLE_HASH_MASK);
> 
> 	rcu_read_lock();
> -	list_for_each_entry_rcu(h, &bucket->head, h_link) {
> +	hlist_for_each_entry_rcu(h, &bucket->head, h_link) {
> 		if (h->h_cookie != cookie || h->h_owner != owner)
> 			continue;
> 
> @@ -176,7 +174,7 @@ int class_handle_init(void)
> 	spin_lock_init(&handle_base_lock);
> 	for (bucket = handle_hash + HANDLE_HASH_SIZE - 1; bucket >= handle_hash;
> 	     bucket--) {
> -		INIT_LIST_HEAD(&bucket->head);
> +		INIT_HLIST_HEAD(&bucket->head);
> 		spin_lock_init(&bucket->lock);
> 	}
> 
> @@ -195,7 +193,7 @@ static int cleanup_all_handles(void)
> 		struct portals_handle *h;
> 
> 		spin_lock(&handle_hash[i].lock);
> -		list_for_each_entry_rcu(h, &handle_hash[i].head, h_link) {
> +		hlist_for_each_entry_rcu(h, &handle_hash[i].head, h_link) {
> 			CERROR("force clean handle %#llx addr %p owner %p\n",
> 			       h->h_cookie, h, h->h_owner);
> 
> 
> 

Cheers, Andreas
---
Andreas Dilger
Principal Lustre Architect
Whamcloud