Branch data     Line data    Source code

       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>
       7                 :            : #include <net/net_namespace.h>
       8                 :            : 
       9                 :            : #include "netns.h"
      10                 :            : 
      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                 :            :  */
      24                 :          0 : void locks_start_grace(struct net *net, struct lock_manager *lm)
      25                 :            : {
      26                 :          0 :         struct lockd_net *ln = net_generic(net, lockd_net_id);
      27                 :            : 
      28                 :            :         spin_lock(&grace_lock);
      29                 :          0 :         list_add(&lm->list, &ln->grace_list);
      30                 :            :         spin_unlock(&grace_lock);
      31                 :          0 : }
      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                 :          0 : void locks_end_grace(struct lock_manager *lm)
      45                 :            : {
      46                 :            :         spin_lock(&grace_lock);
      47                 :          0 :         list_del_init(&lm->list);
      48                 :            :         spin_unlock(&grace_lock);
      49                 :          0 : }
      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                 :            :  */
      59                 :          0 : int locks_in_grace(struct net *net)
      60                 :            : {
      61                 :          0 :         struct lockd_net *ln = net_generic(net, lockd_net_id);
      62                 :            : 
      63                 :          0 :         return !list_empty(&ln->grace_list);
      64                 :            : }
      65                 :            : EXPORT_SYMBOL_GPL(locks_in_grace);