[PATCH 1/8] lockd: nfsd4: use same grace period for lockd and nfsd4

[J. Bruce Fields]

From: J. Bruce Fields <bfields at fieldses.org>

Both lockd and (in the nfsv4 case) nfsd enforce a "grace period" after
reboot, during which clients may reclaim locks from the previous server
instance, but may not acquire new locks.

Currently the lockd and nfsd enforce grace periods of different lengths.
This may cause problems when we reboot a server with both v2/v3 and v4
clients.  For example, if the lockd grace period is shorter (as is likely
the case), then a v3 client might acquire a new lock that conflicts with a
lock already held (but not yet reclaimed) by a v4 client.

This patch calculates a lease time that lockd and nfsd can both use.

Signed-off-by: Marc Eshel <eshel at almaden.ibm.com>
Signed-off-by: J. Bruce Fields <bfields at citi.umich.edu>
---
 fs/lockd/svc.c             |   31 ++++++++++++++++++++++++-------
 fs/nfsd/lockd.c            |    1 +
 fs/nfsd/nfs4state.c        |    9 ++++++++-
 include/linux/lockd/bind.h |    9 +++++++++
 4 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
index 126b1bf..6378572 100644
--- a/fs/lockd/svc.c
+++ b/fs/lockd/svc.c
@@ -75,18 +75,35 @@ static const int		nlm_port_min = 0, nlm_port_max = 65535;
 
 static struct ctl_table_header * nlm_sysctl_table;
 
-static unsigned long set_grace_period(void)
+static time_t get_lockd_grace_period(void)
 {
-	unsigned long grace_period;
-
 	/* Note: nlm_timeout should always be nonzero */
 	if (nlm_grace_period)
-		grace_period = ((nlm_grace_period + nlm_timeout - 1)
-				/ nlm_timeout) * nlm_timeout * HZ;
+		return ((nlm_grace_period + nlm_timeout - 1)
+				/ nlm_timeout) * nlm_timeout;
 	else
-		grace_period = nlm_timeout * 5 * HZ;
+		return nlm_timeout * 5;
+}
+
+time_t get_nfs_grace_period(void)
+{
+	time_t lockdgrace = get_lockd_grace_period();
+	time_t nfsdgrace = 0;
+
+	if (nlmsvc_ops)
+		nfsdgrace = nlmsvc_ops->get_grace_period();
+
+	return max(lockdgrace, nfsdgrace);
+}
+EXPORT_SYMBOL(get_nfs_grace_period);
+
+static unsigned long set_grace_period(void)
+{
+	time_t grace_period;
+
+	grace_period = get_nfs_grace_period();
 	nlmsvc_grace_period = 1;
-	return grace_period + jiffies;
+	return grace_period * HZ + jiffies;
 }
 
 static inline void clear_grace_period(void)
diff --git a/fs/nfsd/lockd.c b/fs/nfsd/lockd.c
index 221acd1..9e4a568 100644
--- a/fs/nfsd/lockd.c
+++ b/fs/nfsd/lockd.c
@@ -65,6 +65,7 @@ nlm_fclose(struct file *filp)
 static struct nlmsvc_binding	nfsd_nlm_ops = {
 	.fopen		= nlm_fopen,		/* open file for locking */
 	.fclose		= nlm_fclose,		/* close file */
+	.get_grace_period = get_nfs4_grace_period,
 };
 
 void
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 3cc8ce4..50e0d44 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -51,6 +51,7 @@
 #include <linux/namei.h>
 #include <linux/mutex.h>
 #include <linux/lockd/bind.h>
+#include <linux/module.h>
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
@@ -3191,6 +3192,12 @@ nfsd4_load_reboot_recovery_data(void)
 		printk("NFSD: Failure reading reboot recovery data\n");
 }
 
+time_t
+get_nfs4_grace_period(void)
+{
+	return max(user_lease_time, lease_time);
+}
+
 /* initialization to perform when the nfsd service is started: */
 
 static void
@@ -3199,7 +3206,7 @@ __nfs4_state_start(void)
 	time_t grace_time;
 
 	boot_time = get_seconds();
-	grace_time = max(user_lease_time, lease_time);
+	grace_time = get_nfs_grace_period();
 	lease_time = user_lease_time;
 	in_grace = 1;
 	printk("NFSD: starting %ld-second grace period\n", grace_time);
diff --git a/include/linux/lockd/bind.h b/include/linux/lockd/bind.h
index 246de1d..df008eb 100644
--- a/include/linux/lockd/bind.h
+++ b/include/linux/lockd/bind.h
@@ -27,6 +27,7 @@ struct nlmsvc_binding {
 						struct nfs_fh *,
 						struct file **);
 	void			(*fclose)(struct file *);
+	time_t			(*get_grace_period)(void);
 };
 
 extern struct nlmsvc_binding *	nlmsvc_ops;
@@ -38,4 +39,12 @@ extern int	nlmclnt_proc(struct inode *, int, struct file_lock *);
 extern int	lockd_up(int proto);
 extern void	lockd_down(void);
 
+time_t get_nfs_grace_period(void);
+
+#ifdef CONFIG_NFSD_V4
+time_t get_nfs4_grace_period(void);
+#else
+static inline void get_nfs4_grace_period(void) {return 0;}
+#endif
+
 #endif /* LINUX_LOCKD_BIND_H */
-- 
1.5.2.rc3