[mirror_ubuntu-zesty-kernel.git] / fs / lockd / grace.c

/*
 * Common code for control of lockd and nfsv4 grace periods.
 */

#include <linux/module.h>
#include <linux/lockd/bind.h>
#include <net/net_namespace.h>

#include "netns.h"

static DEFINE_SPINLOCK(grace_lock);

/**
 * locks_start_grace
 * @lm: who this grace period is for
 *
 * A grace period is a period during which locks should not be given
 * out.  Currently grace periods are only enforced by the two lock
 * managers (lockd and nfsd), using the locks_in_grace() function to
 * check when they are in a grace period.
 *
 * This function is called to start a grace period.
 */
void locks_start_grace(struct net *net, struct lock_manager *lm)
{
	struct lockd_net *ln = net_generic(net, lockd_net_id);

	spin_lock(&grace_lock);
	list_add(&lm->list, &ln->grace_list);
	spin_unlock(&grace_lock);
}
EXPORT_SYMBOL_GPL(locks_start_grace);

/**
 * locks_end_grace
 * @lm: who this grace period is for
 *
 * Call this function to state that the given lock manager is ready to
 * resume regular locking.  The grace period will not end until all lock
 * managers that called locks_start_grace() also call locks_end_grace().
 * Note that callers count on it being safe to call this more than once,
 * and the second call should be a no-op.
 */
void locks_end_grace(struct lock_manager *lm)
{
	spin_lock(&grace_lock);
	list_del_init(&lm->list);
	spin_unlock(&grace_lock);
}
EXPORT_SYMBOL_GPL(locks_end_grace);

/**
 * locks_in_grace
 *
 * Lock managers call this function to determine when it is OK for them
 * to answer ordinary lock requests, and when they should accept only
 * lock reclaims.
 */
int locks_in_grace(struct net *net)
{
	struct lockd_net *ln = net_generic(net, lockd_net_id);

	return !list_empty(&ln->grace_list);
}
EXPORT_SYMBOL_GPL(locks_in_grace);
Commit	Line	Data
af558e33 BF	1	/*
	2	* Common code for control of lockd and nfsv4 grace periods.
	3	*/
	4
	5	#include <linux/module.h>
	6	#include <linux/lockd/bind.h>
db9c4553 SK	7	#include <net/net_namespace.h>
	8
	9	#include "netns.h"
af558e33	10
af558e33 BF	11	static DEFINE_SPINLOCK(grace_lock);
	12
	13	/**
	14	* locks_start_grace
	15	* @lm: who this grace period is for
	16	*
	17	* A grace period is a period during which locks should not be given
	18	* out. Currently grace periods are only enforced by the two lock
	19	* managers (lockd and nfsd), using the locks_in_grace() function to
	20	* check when they are in a grace period.
	21	*
	22	* This function is called to start a grace period.
	23	*/
5ccb0066	24	void locks_start_grace(struct net net, struct lock_manager lm)
af558e33	25	{
db9c4553 SK	26	struct lockd_net *ln = net_generic(net, lockd_net_id);
db9c4553 SK	27
af558e33	28	spin_lock(&grace_lock);
db9c4553	29	list_add(&lm->list, &ln->grace_list);
af558e33 BF	30	spin_unlock(&grace_lock);
	31	}
	32	EXPORT_SYMBOL_GPL(locks_start_grace);
	33
	34	/**
	35	* locks_end_grace
	36	* @lm: who this grace period is for
	37	*
	38	* Call this function to state that the given lock manager is ready to
	39	* resume regular locking. The grace period will not end until all lock
	40	* managers that called locks_start_grace() also call locks_end_grace().
	41	* Note that callers count on it being safe to call this more than once,
	42	* and the second call should be a no-op.
	43	*/
	44	void locks_end_grace(struct lock_manager *lm)
	45	{
	46	spin_lock(&grace_lock);
	47	list_del_init(&lm->list);
	48	spin_unlock(&grace_lock);
	49	}
	50	EXPORT_SYMBOL_GPL(locks_end_grace);
	51
	52	/**
	53	* locks_in_grace
	54	*
	55	* Lock managers call this function to determine when it is OK for them
	56	* to answer ordinary lock requests, and when they should accept only
	57	* lock reclaims.
	58	*/
5ccb0066	59	int locks_in_grace(struct net *net)
af558e33	60	{
db9c4553 SK	61	struct lockd_net *ln = net_generic(net, lockd_net_id);
	62
	63	return !list_empty(&ln->grace_list);
af558e33 BF	64	}
af558e33 BF	65	EXPORT_SYMBOL_GPL(locks_in_grace);