139 lines
3.3 KiB
C
139 lines
3.3 KiB
C
/*
|
|
* Common code for control of lockd and nfsv4 grace periods.
|
|
*
|
|
* Transplanted from lockd code
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <net/net_namespace.h>
|
|
#include <net/netns/generic.h>
|
|
#include <linux/fs.h>
|
|
|
|
static unsigned int grace_net_id;
|
|
static DEFINE_SPINLOCK(grace_lock);
|
|
|
|
/**
|
|
* locks_start_grace
|
|
* @net: net namespace that this lock manager belongs to
|
|
* @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 list_head *grace_list = net_generic(net, grace_net_id);
|
|
|
|
spin_lock(&grace_lock);
|
|
if (list_empty(&lm->list))
|
|
list_add(&lm->list, grace_list);
|
|
else
|
|
WARN(1, "double list_add attempt detected in net %x %s\n",
|
|
net->ns.inum, (net == &init_net) ? "(init_net)" : "");
|
|
spin_unlock(&grace_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(locks_start_grace);
|
|
|
|
/**
|
|
* locks_end_grace
|
|
* @net: net namespace that this lock manager belongs to
|
|
* @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);
|
|
|
|
static bool
|
|
__state_in_grace(struct net *net, bool open)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
struct lock_manager *lm;
|
|
|
|
if (!open)
|
|
return !list_empty(grace_list);
|
|
|
|
list_for_each_entry(lm, grace_list, list) {
|
|
if (lm->block_opens)
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
bool locks_in_grace(struct net *net)
|
|
{
|
|
return __state_in_grace(net, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(locks_in_grace);
|
|
|
|
bool opens_in_grace(struct net *net)
|
|
{
|
|
return __state_in_grace(net, true);
|
|
}
|
|
EXPORT_SYMBOL_GPL(opens_in_grace);
|
|
|
|
static int __net_init
|
|
grace_init_net(struct net *net)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
|
|
INIT_LIST_HEAD(grace_list);
|
|
return 0;
|
|
}
|
|
|
|
static void __net_exit
|
|
grace_exit_net(struct net *net)
|
|
{
|
|
struct list_head *grace_list = net_generic(net, grace_net_id);
|
|
|
|
WARN_ONCE(!list_empty(grace_list),
|
|
"net %x %s: grace_list is not empty\n",
|
|
net->ns.inum, __func__);
|
|
}
|
|
|
|
static struct pernet_operations grace_net_ops = {
|
|
.init = grace_init_net,
|
|
.exit = grace_exit_net,
|
|
.id = &grace_net_id,
|
|
.size = sizeof(struct list_head),
|
|
};
|
|
|
|
static int __init
|
|
init_grace(void)
|
|
{
|
|
return register_pernet_subsys(&grace_net_ops);
|
|
}
|
|
|
|
static void __exit
|
|
exit_grace(void)
|
|
{
|
|
unregister_pernet_subsys(&grace_net_ops);
|
|
}
|
|
|
|
MODULE_AUTHOR("Jeff Layton <jlayton@primarydata.com>");
|
|
MODULE_LICENSE("GPL");
|
|
module_init(init_grace)
|
|
module_exit(exit_grace)
|