diff options
author | Arjan van de Ven <arjan@linux.intel.com> | 2008-10-17 09:20:26 -0700 |
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committer | Arjan van de Ven <arjan@linux.intel.com> | 2008-10-17 09:20:26 -0700 |
commit | 651dab4264e4ba0e563f5ff56f748127246e9065 (patch) | |
tree | 016630974bdcb00fe529b673f96d389e0fd6dc94 /fs/lockd/grace.c | |
parent | 40b8606253552109815786e5d4b0de98782d31f5 (diff) | |
parent | 2e532d68a2b3e2aa6b19731501222069735c741c (diff) |
Merge commit 'linus/master' into merge-linus
Conflicts:
arch/x86/kvm/i8254.c
Diffstat (limited to 'fs/lockd/grace.c')
-rw-r--r-- | fs/lockd/grace.c | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/fs/lockd/grace.c b/fs/lockd/grace.c new file mode 100644 index 00000000000..183cc1f0af1 --- /dev/null +++ b/fs/lockd/grace.c @@ -0,0 +1,59 @@ +/* + * Common code for control of lockd and nfsv4 grace periods. + */ + +#include <linux/module.h> +#include <linux/lockd/bind.h> + +static LIST_HEAD(grace_list); +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 lock_manager *lm) +{ + spin_lock(&grace_lock); + list_add(&lm->list, &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(void) +{ + return !list_empty(&grace_list); +} +EXPORT_SYMBOL_GPL(locks_in_grace); |