NFSv4: Remove obsolete state_owner and lock_owner semaphores

 OPEN, CLOSE, etc no longer need these semaphores to ensure ordering of
 requests.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4_fs.h

@@ -125,16 +125,11 @@ static inline void nfs_confirm_seqid(struct nfs_seqid_counter *seqid, int status
  * NFS4 state_owners and lock_owners are simply labels for ordered
  * sequences of RPC calls. Their sole purpose is to provide once-only
  * semantics by allowing the server to identify replayed requests.
- *
- * The ->so_sema is held during all state_owner seqid-mutating operations:
- * OPEN, OPEN_DOWNGRADE, and CLOSE. Its purpose is to properly serialize
- * so_seqid.
  */
 struct nfs4_state_owner {
 	struct list_head     so_list;	 /* per-clientid list of state_owners */
 	struct nfs4_client   *so_client;
 	u32                  so_id;      /* 32-bit identifier, unique */
-	struct semaphore     so_sema;
 	atomic_t	     so_count;
 
 	struct rpc_cred	     *so_cred;	 /* Associated cred */
@@ -183,7 +178,6 @@ struct nfs4_state {
 	struct inode *inode;		/* Pointer to the inode */
 
 	unsigned long flags;		/* Do we hold any locks? */
-	struct semaphore lock_sema;	/* Serializes file locking operations */
 	spinlock_t state_lock;		/* Protects the lock_states list */
 
 	nfs4_stateid stateid;

fs/nfs/nfs4proc.c

@@ -224,7 +224,6 @@ static void update_open_stateid(struct nfs4_state *state, nfs4_stateid *stateid,
 /*
  * OPEN_RECLAIM:
  * 	reclaim state on the server after a reboot.
- * 	Assumes caller is holding the sp->so_sem
  */
 static int _nfs4_open_reclaim(struct nfs4_state_owner *sp, struct nfs4_state *state)
 {
@@ -322,7 +321,6 @@ static int _nfs4_open_delegation_recall(struct dentry *dentry, struct nfs4_state
 	};
 	int status = 0;
 
-	down(&sp->so_sema);
 	if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 		goto out;
 	if (state->state == 0)
@@ -342,7 +340,6 @@ static int _nfs4_open_delegation_recall(struct dentry *dentry, struct nfs4_state
 	}
 	nfs_free_seqid(arg.seqid);
 out:
-	up(&sp->so_sema);
 	dput(parent);
 	return status;
 }
@@ -595,7 +592,6 @@ static int _nfs4_open_delegated(struct inode *inode, int flags, struct rpc_cred
 		dprintk("%s: nfs4_get_state_owner failed!\n", __FUNCTION__);
 		goto out_err;
 	}
-	down(&sp->so_sema);
 	state = nfs4_get_open_state(inode, sp);
 	if (state == NULL)
 		goto out_err;
@@ -620,7 +616,6 @@ static int _nfs4_open_delegated(struct inode *inode, int flags, struct rpc_cred
 	set_bit(NFS_DELEGATED_STATE, &state->flags);
 	update_open_stateid(state, &delegation->stateid, open_flags);
 out_ok:
-	up(&sp->so_sema);
 	nfs4_put_state_owner(sp);
 	up_read(&nfsi->rwsem);
 	up_read(&clp->cl_sem);
@@ -631,7 +626,6 @@ out_err:
 	if (sp != NULL) {
 		if (state != NULL)
 			nfs4_put_open_state(state);
-		up(&sp->so_sema);
 		nfs4_put_state_owner(sp);
 	}
 	up_read(&nfsi->rwsem);
@@ -696,7 +690,6 @@ static int _nfs4_do_open(struct inode *dir, struct dentry *dentry, int flags, st
 	} else
 		o_arg.u.attrs = sattr;
 	/* Serialization for the sequence id */
-	down(&sp->so_sema);
 
 	o_arg.seqid = nfs_alloc_seqid(&sp->so_seqid);
 	if (o_arg.seqid == NULL)
@@ -716,7 +709,6 @@ static int _nfs4_do_open(struct inode *dir, struct dentry *dentry, int flags, st
 	if (o_res.delegation_type != 0)
 		nfs_inode_set_delegation(inode, cred, &o_res);
 	nfs_free_seqid(o_arg.seqid);
-	up(&sp->so_sema);
 	nfs4_put_state_owner(sp);
 	up_read(&clp->cl_sem);
 	*res = state;
@@ -726,7 +718,6 @@ out_err:
 		if (state != NULL)
 			nfs4_put_open_state(state);
 		nfs_free_seqid(o_arg.seqid);
-		up(&sp->so_sema);
 		nfs4_put_state_owner(sp);
 	}
 	/* Note: clp->cl_sem must be released before nfs4_put_open_state()! */
@@ -833,7 +824,6 @@ static void nfs4_free_closedata(struct nfs4_closedata *calldata)
 
 	nfs4_put_open_state(calldata->state);
 	nfs_free_seqid(calldata->arg.seqid);
-	up(&sp->so_sema);
 	nfs4_put_state_owner(sp);
 	up_read(&server->nfs4_state->cl_sem);
 	kfree(calldata);
@@ -2702,7 +2692,6 @@ static int _nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock
 
 	down_read(&clp->cl_sem);
 	nlo.clientid = clp->cl_clientid;
-	down(&state->lock_sema);
 	status = nfs4_set_lock_state(state, request);
 	if (status != 0)
 		goto out;
@@ -2729,7 +2718,6 @@ static int _nfs4_proc_getlk(struct nfs4_state *state, int cmd, struct file_lock
 		status = 0;
 	}
 out:
-	up(&state->lock_sema);
 	up_read(&clp->cl_sem);
 	return status;
 }
@@ -2791,7 +2779,6 @@ static int _nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock
 	int status;
 			
 	down_read(&clp->cl_sem);
-	down(&state->lock_sema);
 	status = nfs4_set_lock_state(state, request);
 	if (status != 0)
 		goto out;
@@ -2813,7 +2800,6 @@ static int _nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock
 				sizeof(lsp->ls_stateid.data));
 	nfs_free_seqid(luargs.seqid);
 out:
-	up(&state->lock_sema);
 	if (status == 0)
 		do_vfs_lock(request->fl_file, request);
 	up_read(&clp->cl_sem);
@@ -2877,7 +2863,6 @@ static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *r
 		largs.u.open_lock = &otl;
 		largs.new_lock_owner = 1;
 		arg.u.lock = &largs;
-		down(&owner->so_sema);
 		otl.open_seqid = nfs_alloc_seqid(&owner->so_seqid);
 		if (otl.open_seqid != NULL) {
 			status = rpc_call_sync(server->client, &msg, RPC_TASK_NOINTR);
@@ -2885,7 +2870,6 @@ static int _nfs4_do_setlk(struct nfs4_state *state, int cmd, struct file_lock *r
 			nfs_increment_open_seqid(status, otl.open_seqid);
 			nfs_free_seqid(otl.open_seqid);
 		}
-		up(&owner->so_sema);
 		if (status == 0)
 			nfs_confirm_seqid(&lsp->ls_seqid, 0);
 	} else {
@@ -2944,11 +2928,9 @@ static int _nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock
 	int status;
 
 	down_read(&clp->cl_sem);
-	down(&state->lock_sema);
 	status = nfs4_set_lock_state(state, request);
 	if (status == 0)
 		status = _nfs4_do_setlk(state, cmd, request, 0);
-	up(&state->lock_sema);
 	if (status == 0) {
 		/* Note: we always want to sleep here! */
 		request->fl_flags |= FL_SLEEP;

fs/nfs/nfs4state.c

@@ -267,7 +267,6 @@ nfs4_alloc_state_owner(void)
 	sp = kzalloc(sizeof(*sp),GFP_KERNEL);
 	if (!sp)
 		return NULL;
-	init_MUTEX(&sp->so_sema);
 	INIT_LIST_HEAD(&sp->so_states);
 	INIT_LIST_HEAD(&sp->so_delegations);
 	rpc_init_wait_queue(&sp->so_sequence.wait, "Seqid_waitqueue");
@@ -362,7 +361,6 @@ nfs4_alloc_open_state(void)
 	memset(state->stateid.data, 0, sizeof(state->stateid.data));
 	atomic_set(&state->count, 1);
 	INIT_LIST_HEAD(&state->lock_states);
-	init_MUTEX(&state->lock_sema);
 	spin_lock_init(&state->state_lock);
 	return state;
 }
@@ -444,7 +442,6 @@ nfs4_get_open_state(struct inode *inode, struct nfs4_state_owner *owner)
 	state = __nfs4_find_state_byowner(inode, owner);
 	if (state == NULL && new != NULL) {
 		state = new;
-		/* Caller *must* be holding owner->so_sem */
 		/* Note: The reclaim code dictates that we add stateless
 		 * and read-only stateids to the end of the list */
 		list_add_tail(&state->open_states, &owner->so_states);
@@ -464,7 +461,7 @@ out:
 
 /*
  * Beware! Caller must be holding exactly one
- * reference to clp->cl_sem and owner->so_sema!
+ * reference to clp->cl_sem!
  */
 void nfs4_put_open_state(struct nfs4_state *state)
 {
@@ -485,7 +482,6 @@ void nfs4_put_open_state(struct nfs4_state *state)
 
 /*
  * Beware! Caller must be holding no references to clp->cl_sem!
- * of owner->so_sema!
  */
 void nfs4_close_state(struct nfs4_state *state, mode_t mode)
 {
@@ -496,7 +492,6 @@ void nfs4_close_state(struct nfs4_state *state, mode_t mode)
 
 	atomic_inc(&owner->so_count);
 	down_read(&clp->cl_sem);
-	down(&owner->so_sema);
 	/* Protect against nfs4_find_state() */
 	spin_lock(&inode->i_lock);
 	if (mode & FMODE_READ)
@@ -527,7 +522,6 @@ void nfs4_close_state(struct nfs4_state *state, mode_t mode)
 	}
 out:
 	nfs4_put_open_state(state);
-	up(&owner->so_sema);
 	nfs4_put_state_owner(owner);
 	up_read(&clp->cl_sem);
 }
@@ -553,7 +547,6 @@ __nfs4_find_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)
  * Return a compatible lock_state. If no initialized lock_state structure
  * exists, return an uninitialized one.
  *
- * The caller must be holding state->lock_sema
  */
 static struct nfs4_lock_state *nfs4_alloc_lock_state(struct nfs4_state *state, fl_owner_t fl_owner)
 {
@@ -577,7 +570,7 @@ static struct nfs4_lock_state *nfs4_alloc_lock_state(struct nfs4_state *state, f
  * Return a compatible lock_state. If no initialized lock_state structure
  * exists, return an uninitialized one.
  *
- * The caller must be holding state->lock_sema and clp->cl_sem
+ * The caller must be holding clp->cl_sem
  */
 static struct nfs4_lock_state *nfs4_get_lock_state(struct nfs4_state *state, fl_owner_t owner)
 {
@@ -711,7 +704,7 @@ void nfs_free_seqid(struct nfs_seqid *seqid)
 }
 
 /*
- * Called with sp->so_sema and clp->cl_sem held.
+ * Called with clp->cl_sem held.
  *
  * Increment the seqid if the OPEN/OPEN_DOWNGRADE/CLOSE succeeded, or
  * failed with a seqid incrementing error -
@@ -750,7 +743,7 @@ void nfs_increment_open_seqid(int status, struct nfs_seqid *seqid)
 }
 
 /*
- * Called with ls->lock_sema and clp->cl_sem held.
+ * Called with clp->cl_sem held.
  *
  * Increment the seqid if the LOCK/LOCKU succeeded, or
  * failed with a seqid incrementing error -