nfsd: common grace period control

Rewrite grace period code to unify management of grace period across
lockd and nfsd.  The current code has lockd and nfsd cooperate to
compute a grace period which is satisfactory to them both, and then
individually enforce it.  This creates a slight race condition, since
the enforcement is not coordinated.  It's also more complicated than
necessary.

Here instead we have lockd and nfsd each inform common code when they
enter the grace period, and when they're ready to leave the grace
period, and allow normal locking only after both of them are ready to
leave.

We also expect the locks_start_grace()/locks_end_grace() interface here
to be simpler to build on for future cluster/high-availability work,
which may require (for example) putting individual filesystems into
grace, or enforcing grace periods across multiple cluster nodes.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 15 insertions, 19 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 1578d7a2667e..0cc7ff5d5ab5 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -61,7 +61,6 @@
 static time_t lease_time = 90;     /* default lease time */
 static time_t user_lease_time = 90;
 static time_t boot_time;
-static int in_grace = 1;
 static u32 current_ownerid = 1;
 static u32 current_fileid = 1;
 static u32 current_delegid = 1;
@@ -1640,7 +1639,7 @@ nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_sta
                 case NFS4_OPEN_CLAIM_NULL:
                         /* Let's not give out any delegations till everyone's
                          * had the chance to reclaim theirs.... */
-                        if (nfs4_in_grace())
+                        if (locks_in_grace())
                                 goto out;
                         if (!atomic_read(&cb->cb_set) || !sop->so_confirmed)
                                 goto out;
@@ -1816,12 +1815,15 @@ out:
         return status;
 }
 
+struct lock_manager nfsd4_manager = {
+};
+
 static void
-end_grace(void)
+nfsd4_end_grace(void)
 {
         dprintk("NFSD: end of grace period\n");
         nfsd4_recdir_purge_old();
-        in_grace = 0;
+        locks_end_grace(&nfsd4_manager);
 }
 
 static time_t
@@ -1838,8 +1840,8 @@ nfs4_laundromat(void)
         nfs4_lock_state();
 
         dprintk("NFSD: laundromat service - starting\n");
-        if (in_grace)
-                end_grace();
+        if (locks_in_grace())
+                nfsd4_end_grace();
         list_for_each_safe(pos, next, &client_lru) {
                 clp = list_entry(pos, struct nfs4_client, cl_lru);
                 if (time_after((unsigned long)clp->cl_time, (unsigned long)cutoff)) {
@@ -1974,7 +1976,7 @@ check_special_stateids(svc_fh *current_fh, stateid_t *stateid, int flags)
                 return nfserr_bad_stateid;
         else if (ONE_STATEID(stateid) && (flags & RD_STATE))
                 return nfs_ok;
-        else if (nfs4_in_grace()) {
+        else if (locks_in_grace()) {
                 /* Answer in remaining cases depends on existance of
                  * conflicting state; so we must wait out the grace period. */
                 return nfserr_grace;
@@ -1993,7 +1995,7 @@ check_special_stateids(svc_fh *current_fh, stateid_t *stateid, int flags)
 static inline int
 io_during_grace_disallowed(struct inode *inode, int flags)
 {
-        return nfs4_in_grace() && (flags & (RD_STATE | WR_STATE))
+        return locks_in_grace() && (flags & (RD_STATE | WR_STATE))
                 && mandatory_lock(inode);
 }
 
@@ -2693,10 +2695,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         filp = lock_stp->st_vfs_file;
 
         status = nfserr_grace;
-        if (nfs4_in_grace() && !lock->lk_reclaim)
+        if (locks_in_grace() && !lock->lk_reclaim)
                 goto out;
         status = nfserr_no_grace;
-        if (!nfs4_in_grace() && lock->lk_reclaim)
+        if (!locks_in_grace() && lock->lk_reclaim)
                 goto out;
 
         locks_init_lock(&file_lock);
@@ -2779,7 +2781,7 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         int error;
         __be32 status;
 
-        if (nfs4_in_grace())
+        if (locks_in_grace())
                 return nfserr_grace;
 
         if (check_lock_length(lockt->lt_offset, lockt->lt_length))
@@ -3192,9 +3194,9 @@ __nfs4_state_start(void)
         unsigned long grace_time;
 
         boot_time = get_seconds();
-        grace_time = get_nfs_grace_period();
+        grace_time = get_nfs4_grace_period();
         lease_time = user_lease_time;
-        in_grace = 1;
+        locks_start_grace(&nfsd4_manager);
         printk(KERN_INFO "NFSD: starting %ld-second grace period\n",
                grace_time/HZ);
         laundry_wq = create_singlethread_workqueue("nfsd4");
@@ -3213,12 +3215,6 @@ nfs4_state_start(void)
         return;
 }
 
-int
-nfs4_in_grace(void)
-{
-        return in_grace;
-}
-
 time_t
 nfs4_lease_time(void)
 {