[Cluster-devel] [PATCH v2 09/14] locks: convert fl_link to a hlist_node

[Jeff Layton <jlayton@redhat.com>]

Testing has shown that iterating over the blocked_list for deadlock
detection turns out to be a bottleneck. In order to alleviate that,
begin the process of turning it into a hashtable. We start by turning
the fl_link into a hlist_node and the global lists into hlists. A later
patch will do the conversion of the blocked_list to a hashtable.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 fs/locks.c         |   26 +++++++++++++-------------
 include/linux/fs.h |    2 +-
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index b8cd1b1..28959bc 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -153,8 +153,8 @@ int lease_break_time = 45;
 #define for_each_lock(inode, lockp) \
 	for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)
 
-static LIST_HEAD(file_lock_list);
-static LIST_HEAD(blocked_list);
+static HLIST_HEAD(file_lock_list);
+static HLIST_HEAD(blocked_list);
 
 /* Protects the two list heads above */
 static DEFINE_SPINLOCK(file_lock_lock);
@@ -163,7 +163,7 @@ static struct kmem_cache *filelock_cache __read_mostly;
 
 static void locks_init_lock_heads(struct file_lock *fl)
 {
-	INIT_LIST_HEAD(&fl->fl_link);
+	INIT_HLIST_NODE(&fl->fl_link);
 	INIT_LIST_HEAD(&fl->fl_block);
 	init_waitqueue_head(&fl->fl_wait);
 }
@@ -197,7 +197,7 @@ void locks_free_lock(struct file_lock *fl)
 {
 	BUG_ON(waitqueue_active(&fl->fl_wait));
 	BUG_ON(!list_empty(&fl->fl_block));
-	BUG_ON(!list_empty(&fl->fl_link));
+	BUG_ON(!hlist_unhashed(&fl->fl_link));
 
 	locks_release_private(fl);
 	kmem_cache_free(filelock_cache, fl);
@@ -475,13 +475,13 @@ static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 static inline void
 locks_insert_global_blocked(struct file_lock *waiter)
 {
-	list_add(&waiter->fl_link, &blocked_list);
+	hlist_add_head(&waiter->fl_link, &blocked_list);
 }
 
 static inline void
 __locks_delete_global_blocked(struct file_lock *waiter)
 {
-	list_del_init(&waiter->fl_link);
+	hlist_del_init(&waiter->fl_link);
 }
 
 static inline void
@@ -496,7 +496,7 @@ static inline void
 locks_insert_global_locks(struct file_lock *waiter)
 {
 	spin_lock(&file_lock_lock);
-	list_add_tail(&waiter->fl_link, &file_lock_list);
+	hlist_add_head(&waiter->fl_link, &file_lock_list);
 	spin_unlock(&file_lock_lock);
 }
 
@@ -504,7 +504,7 @@ static inline void
 locks_delete_global_locks(struct file_lock *waiter)
 {
 	spin_lock(&file_lock_lock);
-	list_del_init(&waiter->fl_link);
+	hlist_del_init(&waiter->fl_link);
 	spin_unlock(&file_lock_lock);
 }
 
@@ -729,7 +729,7 @@ static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
 {
 	struct file_lock *fl;
 
-	list_for_each_entry(fl, &blocked_list, fl_link) {
+	hlist_for_each_entry(fl, &blocked_list, fl_link) {
 		if (posix_same_owner(fl, block_fl))
 			return fl->fl_next;
 	}
@@ -2286,11 +2286,11 @@ static int locks_show(struct seq_file *f, void *v)
 {
 	struct file_lock *fl, *bfl;
 
-	fl = list_entry(v, struct file_lock, fl_link);
+	fl = hlist_entry(v, struct file_lock, fl_link);
 
 	lock_get_status(f, fl, *((loff_t *)f->private), "");
 
-	list_for_each_entry(bfl, &blocked_list, fl_link) {
+	hlist_for_each_entry(bfl, &blocked_list, fl_link) {
 		if (bfl->fl_next == fl)
 			lock_get_status(f, bfl, *((loff_t *)f->private), " ->");
 	}
@@ -2304,14 +2304,14 @@ static void *locks_start(struct seq_file *f, loff_t *pos)
 
 	spin_lock(&file_lock_lock);
 	*p = (*pos + 1);
-	return seq_list_start(&file_lock_list, *pos);
+	return seq_hlist_start(&file_lock_list, *pos);
 }
 
 static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
 {
 	loff_t *p = f->private;
 	++*p;
-	return seq_list_next(v, &file_lock_list, pos);
+	return seq_hlist_next(v, &file_lock_list, pos);
 }
 
 static void locks_stop(struct seq_file *f, void *v)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e2f896d..3b340f7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -946,7 +946,7 @@ int locks_in_grace(struct net *);
  */
 struct file_lock {
 	struct file_lock *fl_next;	/* singly linked list for this inode  */
-	struct list_head fl_link;	/* doubly linked list of all locks */
+	struct hlist_node fl_link;	/* node in global lists */
 	struct list_head fl_block;	/* circular list of blocked processes */
 	fl_owner_t fl_owner;
 	unsigned int fl_flags;
-- 
1.7.1