This is a note to let you know that I've just added the patch titled
fput: turn "list_head delayed_fput_list" into llist_head
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fput-turn-list_head-delayed_fput_list-into-llist_head.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4f5e65a1cc90bbb15b9f6cdc362922af1bcc155a Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Date: Mon, 8 Jul 2013 14:24:16 -0700
Subject: fput: turn "list_head delayed_fput_list" into llist_head
From: Oleg Nesterov <oleg@xxxxxxxxxx>
commit 4f5e65a1cc90bbb15b9f6cdc362922af1bcc155a upstream.
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: Oleg Nesterov <oleg@xxxxxxxxxx>
Suggested-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrey Vagin <avagin@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Wang Kai <morgan.wang@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/file_table.c | 25 ++++++++++---------------
include/linux/fs.h | 2 ++
2 files changed, 12 insertions(+), 15 deletions(-)
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -265,18 +265,15 @@ static void __fput(struct file *file)
mntput(mnt);
}
-static DEFINE_SPINLOCK(delayed_fput_lock);
-static LIST_HEAD(delayed_fput_list);
+static LLIST_HEAD(delayed_fput_list);
static void delayed_fput(struct work_struct *unused)
{
- LIST_HEAD(head);
- spin_lock_irq(&delayed_fput_lock);
- list_splice_init(&delayed_fput_list, &head);
- spin_unlock_irq(&delayed_fput_lock);
- while (!list_empty(&head)) {
- struct file *f = list_first_entry(&head, struct file, f_u.fu_list);
- list_del_init(&f->f_u.fu_list);
- __fput(f);
+ struct llist_node *node = llist_del_all(&delayed_fput_list);
+ struct llist_node *next;
+
+ for (; node; node = next) {
+ next = llist_next(node);
+ __fput(llist_entry(node, struct file, f_u.fu_llist));
}
}
@@ -306,7 +303,6 @@ void fput(struct file *file)
{
if (atomic_long_dec_and_test(&file->f_count)) {
struct task_struct *task = current;
- unsigned long flags;
file_sb_list_del(file);
if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
@@ -314,10 +310,9 @@ void fput(struct file *file)
if (!task_work_add(task, &file->f_u.fu_rcuhead, true))
return;
}
- spin_lock_irqsave(&delayed_fput_lock, flags);
- list_add(&file->f_u.fu_list, &delayed_fput_list);
- schedule_work(&delayed_fput_work);
- spin_unlock_irqrestore(&delayed_fput_lock, flags);
+
+ if (llist_add(&file->f_u.fu_llist, &delayed_fput_list))
+ schedule_work(&delayed_fput_work);
}
}
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -10,6 +10,7 @@
#include <linux/stat.h>
#include <linux/cache.h>
#include <linux/list.h>
+#include <linux/llist.h>
#include <linux/radix-tree.h>
#include <linux/rbtree.h>
#include <linux/init.h>
@@ -767,6 +768,7 @@ struct file {
*/
union {
struct list_head fu_list;
+ struct llist_node fu_llist;
struct rcu_head fu_rcuhead;
} f_u;
struct path f_path;
Patches currently in stable-queue which might be from oleg@xxxxxxxxxx are
queue-3.10/fput-turn-list_head-delayed_fput_list-into-llist_head.patch
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