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Commit 59eda0e0 authored by Al Viro's avatar Al Viro
Browse files

new fs_pin killing logics 



Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent fdab684d

fs/fs_pin.c

+48 −6
Original line number Diff line number Diff line 
#include <linux/fs.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/fs_pin.h>

#include "internal.h"
@@ -12,6 +13,10 @@ void pin_remove(struct fs_pin *pin) 
	hlist_del(&pin->m_list);

	hlist_del(&pin->s_list);

	spin_unlock(&pin_lock);

	spin_lock_irq(&pin->wait.lock);

	pin->done = 1;

	wake_up_locked(&pin->wait);

	spin_unlock_irq(&pin->wait.lock);

}



void pin_insert_group(struct fs_pin *pin, struct vfsmount *m, struct hlist_head *p)
@@ -28,19 +33,58 @@ void pin_insert(struct fs_pin *pin, struct vfsmount *m) 
	pin_insert_group(pin, m, &m->mnt_sb->s_pins);

}



void pin_kill(struct fs_pin *p)

{

	wait_queue_t wait;



	if (!p) {

		rcu_read_unlock();

		return;

	}

	init_wait(&wait);

	spin_lock_irq(&p->wait.lock);

	if (likely(!p->done)) {

		p->done = -1;

		spin_unlock_irq(&p->wait.lock);

		rcu_read_unlock();

		p->kill(p);

		return;

	}

	if (p->done > 0) {

		spin_unlock_irq(&p->wait.lock);

		rcu_read_unlock();

		return;

	}

	__add_wait_queue(&p->wait, &wait);

	while (1) {

		set_current_state(TASK_UNINTERRUPTIBLE);

		spin_unlock_irq(&p->wait.lock);

		rcu_read_unlock();

		schedule();

		rcu_read_lock();

		if (likely(list_empty(&wait.task_list)))

			break;

		/* OK, we know p couldn't have been freed yet */

		spin_lock_irq(&p->wait.lock);

		if (p->done > 0) {

			spin_unlock_irq(&p->wait.lock);

			break;

		}

	}

	rcu_read_unlock();

}



void mnt_pin_kill(struct mount *m)

{

	while (1) {

		struct hlist_node *p;

		struct fs_pin *pin;

		rcu_read_lock();

		p = ACCESS_ONCE(m->mnt_pins.first);

		if (!p) {

			rcu_read_unlock();

			break;

		}

		pin = hlist_entry(p, struct fs_pin, m_list);

		pin->kill(pin);

		pin_kill(hlist_entry(p, struct fs_pin, m_list));

	}

}
@@ -48,14 +92,12 @@ void group_pin_kill(struct hlist_head *p) 
{

	while (1) {

		struct hlist_node *q;

		struct fs_pin *pin;

		rcu_read_lock();

		q = ACCESS_ONCE(p->first);

		if (!q) {

			rcu_read_unlock();

			break;

		}

		pin = hlist_entry(q, struct fs_pin, s_list);

		pin->kill(pin);

		pin_kill(hlist_entry(q, struct fs_pin, s_list));

	}

}

include/linux/fs_pin.h

+12 −1
Original line number Diff line number Diff line 
#include <linux/fs.h>

#include <linux/wait.h>



struct fs_pin {

	wait_queue_head_t	wait;

	int			done;

	struct hlist_node	s_list;

	struct hlist_node	m_list;

	void (*kill)(struct fs_pin *);

};



struct vfsmount;



static inline void init_fs_pin(struct fs_pin *p, void (*kill)(struct fs_pin *))

{

	init_waitqueue_head(&p->wait);

	p->kill = kill;

}



void pin_remove(struct fs_pin *);

void pin_insert_group(struct fs_pin *, struct vfsmount *, struct hlist_head *);

void pin_insert(struct fs_pin *, struct vfsmount *);

void pin_kill(struct fs_pin *);

include/linux/pid_namespace.h

+2 −2
Original line number Diff line number Diff line
@@ -19,7 +19,7 @@ struct pidmap { 
#define BITS_PER_PAGE_MASK	(BITS_PER_PAGE-1)

#define PIDMAP_ENTRIES		((PID_MAX_LIMIT+BITS_PER_PAGE-1)/BITS_PER_PAGE)



struct bsd_acct_struct;

struct fs_pin;



struct pid_namespace {

	struct kref kref;
@@ -37,7 +37,7 @@ struct pid_namespace { 
	struct dentry *proc_thread_self;

#endif

#ifdef CONFIG_BSD_PROCESS_ACCT

	struct bsd_acct_struct *bacct;

	struct fs_pin *bacct;

#endif

	struct user_namespace *user_ns;

	struct work_struct proc_work;

kernel/acct.c

+34 −47
Original line number Diff line number Diff line
@@ -76,7 +76,6 @@ int acct_parm[3] = {4, 2, 30}; 
/*

 * External references and all of the globals.

 */

static void do_acct_process(struct bsd_acct_struct *acct);



struct bsd_acct_struct {

	struct fs_pin		pin;
@@ -91,6 +90,8 @@ struct bsd_acct_struct { 
	struct completion	done;

};



static void do_acct_process(struct bsd_acct_struct *acct);



/*

 * Check the amount of free space and suspend/resume accordingly.

 */
@@ -132,13 +133,18 @@ static void acct_put(struct bsd_acct_struct *p) 
		kfree_rcu(p, rcu);

}



static inline struct bsd_acct_struct *to_acct(struct fs_pin *p)

{

	return p ? container_of(p, struct bsd_acct_struct, pin) : NULL;

}



static struct bsd_acct_struct *acct_get(struct pid_namespace *ns)

{

	struct bsd_acct_struct *res;

again:

	smp_rmb();

	rcu_read_lock();

	res = ACCESS_ONCE(ns->bacct);

	res = to_acct(ACCESS_ONCE(ns->bacct));

	if (!res) {

		rcu_read_unlock();

		return NULL;
@@ -150,7 +156,7 @@ static struct bsd_acct_struct *acct_get(struct pid_namespace *ns) 
	}

	rcu_read_unlock();

	mutex_lock(&res->lock);

	if (!res->ns) {

	if (res != to_acct(ACCESS_ONCE(ns->bacct))) {

		mutex_unlock(&res->lock);

		acct_put(res);

		goto again;
@@ -158,51 +164,27 @@ static struct bsd_acct_struct *acct_get(struct pid_namespace *ns) 
	return res;

}



static void close_work(struct work_struct *work)

{

	struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);

	struct file *file = acct->file;

	if (file->f_op->flush)

		file->f_op->flush(file, NULL);

	__fput_sync(file);

	complete(&acct->done);

}



static void acct_kill(struct bsd_acct_struct *acct)

static void acct_pin_kill(struct fs_pin *pin)

{

	if (acct) {

		struct pid_namespace *ns = acct->ns;

	struct bsd_acct_struct *acct = to_acct(pin);

	mutex_lock(&acct->lock);

	do_acct_process(acct);

		INIT_WORK(&acct->work, close_work);

		init_completion(&acct->done);

	schedule_work(&acct->work);

	wait_for_completion(&acct->done);

		pin_remove(&acct->pin);

		cmpxchg(&ns->bacct, acct, NULL);

		acct->ns = NULL;

		atomic_long_dec(&acct->count);

	cmpxchg(&acct->ns->bacct, pin, NULL);

	mutex_unlock(&acct->lock);

	pin_remove(pin);

	acct_put(acct);

}

}



static void acct_pin_kill(struct fs_pin *pin)

static void close_work(struct work_struct *work)

{

	struct bsd_acct_struct *acct;

	acct = container_of(pin, struct bsd_acct_struct, pin);

	if (!atomic_long_inc_not_zero(&acct->count)) {

		rcu_read_unlock();

		cpu_relax();

		return;

	}

	rcu_read_unlock();

	mutex_lock(&acct->lock);

	if (!acct->ns) {

		mutex_unlock(&acct->lock);

		acct_put(acct);

		acct = NULL;

	}

	acct_kill(acct);

	struct bsd_acct_struct *acct = container_of(work, struct bsd_acct_struct, work);

	struct file *file = acct->file;

	if (file->f_op->flush)

		file->f_op->flush(file, NULL);

	__fput_sync(file);

	complete(&acct->done);

}



static int acct_on(struct filename *pathname)
@@ -210,7 +192,8 @@ static int acct_on(struct filename *pathname) 
	struct file *file;

	struct vfsmount *mnt, *internal;

	struct pid_namespace *ns = task_active_pid_ns(current);

	struct bsd_acct_struct *acct, *old;

	struct bsd_acct_struct *acct;

	struct fs_pin *old;

	int err;



	acct = kzalloc(sizeof(struct bsd_acct_struct), GFP_KERNEL);
@@ -252,18 +235,20 @@ static int acct_on(struct filename *pathname) 
	file->f_path.mnt = internal;



	atomic_long_set(&acct->count, 1);

	acct->pin.kill = acct_pin_kill;

	init_fs_pin(&acct->pin, acct_pin_kill);

	acct->file = file;

	acct->needcheck = jiffies;

	acct->ns = ns;

	mutex_init(&acct->lock);

	INIT_WORK(&acct->work, close_work);

	init_completion(&acct->done);

	mutex_lock_nested(&acct->lock, 1);	/* nobody has seen it yet */

	pin_insert(&acct->pin, mnt);



	old = acct_get(ns);

	ns->bacct = acct;

	acct_kill(old);

	rcu_read_lock();

	old = xchg(&ns->bacct, &acct->pin);

	mutex_unlock(&acct->lock);

	pin_kill(old);

	mnt_drop_write(mnt);

	mntput(mnt);

	return 0;
@@ -299,7 +284,8 @@ SYSCALL_DEFINE1(acct, const char __user *, name) 
		mutex_unlock(&acct_on_mutex);

		putname(tmp);

	} else {

		acct_kill(acct_get(task_active_pid_ns(current)));

		rcu_read_lock();

		pin_kill(task_active_pid_ns(current)->bacct);

	}



	return error;
@@ -307,7 +293,8 @@ SYSCALL_DEFINE1(acct, const char __user *, name) 


void acct_exit_ns(struct pid_namespace *ns)

{

	acct_kill(acct_get(ns));

	rcu_read_lock();

	pin_kill(ns->bacct);

}



/*