Commit 4f5e65a1 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Al Viro
Browse files

fput: turn "list_head delayed_fput_list" into llist_head 



fput() and delayed_fput() can use llist and avoid the locking.

This is unlikely path, it is not that this change can improve
the performance, but this way the code looks simpler.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Suggested-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Vagin <avagin@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 64372501

fs/file_table.c

+10 −15
Original line number Original line Diff line number Diff line
@@ -265,18 +265,15 @@ static void __fput(struct file *file) 
	mntput(mnt);

	mntput(mnt);

}

}





static DEFINE_SPINLOCK(delayed_fput_lock);

static LLIST_HEAD(delayed_fput_list);

static LIST_HEAD(delayed_fput_list);

static void delayed_fput(struct work_struct *unused)

static void delayed_fput(struct work_struct *unused)

{

{

	LIST_HEAD(head);

	struct llist_node *node = llist_del_all(&delayed_fput_list);

	spin_lock_irq(&delayed_fput_lock);

	struct llist_node *next;

	list_splice_init(&delayed_fput_list, &head);



	spin_unlock_irq(&delayed_fput_lock);

	for (; node; node = next) {

	while (!list_empty(&head)) {

		next = llist_next(node);

		struct file *f = list_first_entry(&head, struct file, f_u.fu_list);

		__fput(llist_entry(node, struct file, f_u.fu_llist));

		list_del_init(&f->f_u.fu_list);

		__fput(f);

	}

	}

}

}
@@ -306,7 +303,6 @@ void fput(struct file *file) 
{

{

	if (atomic_long_dec_and_test(&file->f_count)) {

	if (atomic_long_dec_and_test(&file->f_count)) {

		struct task_struct *task = current;

		struct task_struct *task = current;

		unsigned long flags;





		file_sb_list_del(file);

		file_sb_list_del(file);

		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {

		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
@@ -320,10 +316,9 @@ void fput(struct file *file) 
			 * fput to avoid leaking *file.

			 * fput to avoid leaking *file.

			 */

			 */

		}

		}

		spin_lock_irqsave(&delayed_fput_lock, flags);



		list_add(&file->f_u.fu_list, &delayed_fput_list);

		if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))

			schedule_work(&delayed_fput_work);

			schedule_work(&delayed_fput_work);

		spin_unlock_irqrestore(&delayed_fput_lock, flags);

	}

	}

}

}

include/linux/fs.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -10,6 +10,7 @@ 
#include <linux/stat.h>

#include <linux/stat.h>

#include <linux/cache.h>

#include <linux/cache.h>

#include <linux/list.h>

#include <linux/list.h>

#include <linux/llist.h>

#include <linux/radix-tree.h>

#include <linux/radix-tree.h>

#include <linux/rbtree.h>

#include <linux/rbtree.h>

#include <linux/init.h>

#include <linux/init.h>
@@ -768,6 +769,7 @@ struct file { 
	 */

	 */

	union {

	union {

		struct list_head	fu_list;

		struct list_head	fu_list;

		struct llist_node	fu_llist;

		struct rcu_head 	fu_rcuhead;

		struct rcu_head 	fu_rcuhead;

	} f_u;

	} f_u;

	struct path		f_path;

	struct path		f_path;