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Commit 139ca04e authored by Jeff Layton's avatar Jeff Layton Committed by Al Viro
Browse files

locks: convert fl_link to a hlist_node 



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: default avatarJeff Layton <jlayton@redhat.com>
Acked-by: default avatarJ. Bruce Fields <bfields@fieldses.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4e8c765d

fs/locks.c

+12 −12
Original line number Diff line number Diff line
@@ -157,13 +157,13 @@ int lease_break_time = 45; 
 * The global file_lock_list is only used for displaying /proc/locks. Protected

 * by the file_lock_lock.

 */

static LIST_HEAD(file_lock_list);

static HLIST_HEAD(file_lock_list);



/*

 * The blocked_list is used to find POSIX lock loops for deadlock detection.

 * Protected by file_lock_lock.

 */

static LIST_HEAD(blocked_list);

static HLIST_HEAD(blocked_list);



/*

 * This lock protects the blocked_list, and the file_lock_list. Generally, if
@@ -188,7 +188,7 @@ 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);

}
@@ -222,7 +222,7 @@ 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);
@@ -500,7 +500,7 @@ static inline void 
locks_insert_global_locks(struct file_lock *fl)

{

	spin_lock(&file_lock_lock);

	list_add_tail(&fl->fl_link, &file_lock_list);

	hlist_add_head(&fl->fl_link, &file_lock_list);

	spin_unlock(&file_lock_lock);

}
@@ -508,20 +508,20 @@ static inline void 
locks_delete_global_locks(struct file_lock *fl)

{

	spin_lock(&file_lock_lock);

	list_del_init(&fl->fl_link);

	hlist_del_init(&fl->fl_link);

	spin_unlock(&file_lock_lock);

}



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);

}



/* Remove waiter from blocker's block list.
@@ -748,7 +748,7 @@ 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;

	}
@@ -2300,7 +2300,7 @@ 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), "");
@@ -2316,14 +2316,14 @@ 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)

include/linux/fs.h

+1 −1
Original line number Diff line number Diff line
@@ -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;