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authorChuck Lever <chuck.lever@oracle.com>2009-06-17 18:02:10 -0700
committerTrond Myklebust <Trond.Myklebust@netapp.com>2009-06-17 18:02:10 -0700
commit6c9dc4255108bab4ef5c177d369b99c3c23492a7 (patch)
tree1369d9d804e276c32ab157e64646888b64ca0640
parent18fc31641925867c871bc75270ce642c039188d3 (diff)
lockd: Update NSM state from SM_MON replies
When rpc.statd starts up in user space at boot time, it attempts to write the latest NSM local state number into /proc/sys/fs/nfs/nsm_local_state. If lockd.ko isn't loaded yet (as is the case in most configurations), that file doesn't exist, thus the kernel's NSM state remains set to its initial value of zero during lockd operation. This is a problem because rpc.statd and lockd use the NSM state number to prevent repeated lock recovery on rebooted hosts. If lockd sends a zero NSM state, but then a delayed SM_NOTIFY with a real NSM state number is received, there is no way for lockd or rpc.statd to distinguish that stale SM_NOTIFY from an actual reboot. Thus lock recovery could be performed after the rebooted host has already started reclaiming locks, and those locks will be lost. We could change /etc/init.d/nfslock so it always modprobes lockd.ko before starting rpc.statd. However, if lockd.ko is ever unloaded and reloaded, we are back at square one, since the NSM state is not preserved across an unload/reload cycle. This may happen frequently on clients that use automounter. A period of NFS inactivity causes lockd.ko to be unloaded, and the kernel loses its NSM state setting. Instead, let's use the fact that rpc.statd plants the local system's NSM state in every SM_MON (and SM_UNMON) reply. lockd performs a synchronous SM_MON upcall to the local rpc.statd _before_ sending its first NLM request to a new remote. This would permit rpc.statd to provide the current NSM state to lockd, even after lockd.ko had been unloaded and reloaded. Note that NLMPROC_LOCK arguments are constructed before the nsm_monitor() call, so we have to rearrange argument construction very slightly to make this all work out. And, the kernel appears to treat NSM state as a u32 (see struct nlm_args and nsm_res). Make nsm_local_state a u32 as well, to ensure we don't get bogus comparison results. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
-rw-r--r--fs/lockd/clntproc.c2
-rw-r--r--fs/lockd/mon.c18
-rw-r--r--include/linux/lockd/lockd.h2
3 files changed, 14 insertions, 8 deletions
diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
index 273e229353f..f2fdcbce143 100644
--- a/fs/lockd/clntproc.c
+++ b/fs/lockd/clntproc.c
@@ -126,7 +126,6 @@ static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
struct nlm_lock *lock = &argp->lock;
nlmclnt_next_cookie(&argp->cookie);
- argp->state = nsm_local_state;
memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh));
lock->caller = utsname()->nodename;
lock->oh.data = req->a_owner;
@@ -521,6 +520,7 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
if (nsm_monitor(host) < 0)
goto out;
+ req->a_args.state = nsm_local_state;
fl->fl_flags |= FL_ACCESS;
status = do_vfs_lock(fl);
diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 6d5d4a4169e..38385336614 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -53,7 +53,7 @@ static DEFINE_SPINLOCK(nsm_lock);
/*
* Local NSM state
*/
-int __read_mostly nsm_local_state;
+u32 __read_mostly nsm_local_state;
int __read_mostly nsm_use_hostnames;
static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
@@ -184,13 +184,19 @@ int nsm_monitor(const struct nlm_host *host)
nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;
status = nsm_mon_unmon(nsm, NSMPROC_MON, &res);
- if (res.status != 0)
+ if (unlikely(res.status != 0))
status = -EIO;
- if (status < 0)
+ if (unlikely(status < 0)) {
printk(KERN_NOTICE "lockd: cannot monitor %s\n", nsm->sm_name);
- else
- nsm->sm_monitored = 1;
- return status;
+ return status;
+ }
+
+ nsm->sm_monitored = 1;
+ if (unlikely(nsm_local_state != res.state)) {
+ nsm_local_state = res.state;
+ dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
+ }
+ return 0;
}
/**
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 51855dfd8ad..c325b187966 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -195,7 +195,7 @@ extern struct svc_procedure nlmsvc_procedures4[];
extern int nlmsvc_grace_period;
extern unsigned long nlmsvc_timeout;
extern int nsm_use_hostnames;
-extern int nsm_local_state;
+extern u32 nsm_local_state;
/*
* Lockd client functions