1 files changed, 820 insertions, 0 deletions

diff --git a/fs/lockd/clntproc.c b/fs/lockd/clntproc.c
new file mode 100644
index 000000000000..a4407619b1f1
--- /dev/null
+++ b/fs/lockd/clntproc.c
@@ -0,0 +1,820 @@
+/*
+ * linux/fs/lockd/clntproc.c
+ *
+ * RPC procedures for the client side NLM implementation
+ *
+ * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/nfs_fs.h>
+#include <linux/utsname.h>
+#include <linux/smp_lock.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/svc.h>
+#include <linux/lockd/lockd.h>
+#include <linux/lockd/sm_inter.h>
+
+#define NLMDBG_FACILITY		NLMDBG_CLIENT
+#define NLMCLNT_GRACE_WAIT	(5*HZ)
+
+static int	nlmclnt_test(struct nlm_rqst *, struct file_lock *);
+static int	nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
+static int	nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
+static void	nlmclnt_unlock_callback(struct rpc_task *);
+static void	nlmclnt_cancel_callback(struct rpc_task *);
+static int	nlm_stat_to_errno(u32 stat);
+static void	nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
+
+/*
+ * Cookie counter for NLM requests
+ */
+static u32	nlm_cookie = 0x1234;
+
+static inline void nlmclnt_next_cookie(struct nlm_cookie *c)
+{
+	memcpy(c->data, &nlm_cookie, 4);
+	memset(c->data+4, 0, 4);
+	c->len=4;
+	nlm_cookie++;
+}
+
+static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner)
+{
+	atomic_inc(&lockowner->count);
+	return lockowner;
+}
+
+static void nlm_put_lockowner(struct nlm_lockowner *lockowner)
+{
+	if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
+		return;
+	list_del(&lockowner->list);
+	spin_unlock(&lockowner->host->h_lock);
+	nlm_release_host(lockowner->host);
+	kfree(lockowner);
+}
+
+static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
+{
+	struct nlm_lockowner *lockowner;
+	list_for_each_entry(lockowner, &host->h_lockowners, list) {
+		if (lockowner->pid == pid)
+			return -EBUSY;
+	}
+	return 0;
+}
+
+static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
+{
+	uint32_t res;
+	do {
+		res = host->h_pidcount++;
+	} while (nlm_pidbusy(host, res) < 0);
+	return res;
+}
+
+static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
+{
+	struct nlm_lockowner *lockowner;
+	list_for_each_entry(lockowner, &host->h_lockowners, list) {
+		if (lockowner->owner != owner)
+			continue;
+		return nlm_get_lockowner(lockowner);
+	}
+	return NULL;
+}
+
+static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner)
+{
+	struct nlm_lockowner *res, *new = NULL;
+
+	spin_lock(&host->h_lock);
+	res = __nlm_find_lockowner(host, owner);
+	if (res == NULL) {
+		spin_unlock(&host->h_lock);
+		new = (struct nlm_lockowner *)kmalloc(sizeof(*new), GFP_KERNEL);
+		spin_lock(&host->h_lock);
+		res = __nlm_find_lockowner(host, owner);
+		if (res == NULL && new != NULL) {
+			res = new;
+			atomic_set(&new->count, 1);
+			new->owner = owner;
+			new->pid = __nlm_alloc_pid(host);
+			new->host = nlm_get_host(host);
+			list_add(&new->list, &host->h_lockowners);
+			new = NULL;
+		}
+	}
+	spin_unlock(&host->h_lock);
+	if (new != NULL)
+		kfree(new);
+	return res;
+}
+
+/*
+ * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
+ */
+static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
+{
+	struct nlm_args	*argp = &req->a_args;
+	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_dentry->d_inode), sizeof(struct nfs_fh));
+	lock->caller  = system_utsname.nodename;
+	lock->oh.data = req->a_owner;
+	lock->oh.len  = sprintf(req->a_owner, "%d@%s",
+				current->pid, system_utsname.nodename);
+	locks_copy_lock(&lock->fl, fl);
+}
+
+static void nlmclnt_release_lockargs(struct nlm_rqst *req)
+{
+	struct file_lock *fl = &req->a_args.lock.fl;
+
+	if (fl->fl_ops && fl->fl_ops->fl_release_private)
+		fl->fl_ops->fl_release_private(fl);
+}
+
+/*
+ * Initialize arguments for GRANTED call. The nlm_rqst structure
+ * has been cleared already.
+ */
+int
+nlmclnt_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
+{
+	locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
+	memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
+	call->a_args.lock.caller = system_utsname.nodename;
+	call->a_args.lock.oh.len = lock->oh.len;
+
+	/* set default data area */
+	call->a_args.lock.oh.data = call->a_owner;
+
+	if (lock->oh.len > NLMCLNT_OHSIZE) {
+		void *data = kmalloc(lock->oh.len, GFP_KERNEL);
+		if (!data) {
+			nlmclnt_freegrantargs(call);
+			return 0;
+		}
+		call->a_args.lock.oh.data = (u8 *) data;
+	}
+
+	memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
+	return 1;
+}
+
+void
+nlmclnt_freegrantargs(struct nlm_rqst *call)
+{
+	struct file_lock *fl = &call->a_args.lock.fl;
+	/*
+	 * Check whether we allocated memory for the owner.
+	 */
+	if (call->a_args.lock.oh.data != (u8 *) call->a_owner) {
+		kfree(call->a_args.lock.oh.data);
+	}
+	if (fl->fl_ops && fl->fl_ops->fl_release_private)
+		fl->fl_ops->fl_release_private(fl);
+}
+
+/*
+ * This is the main entry point for the NLM client.
+ */
+int
+nlmclnt_proc(struct inode *inode, int cmd, struct file_lock *fl)
+{
+	struct nfs_server	*nfssrv = NFS_SERVER(inode);
+	struct nlm_host		*host;
+	struct nlm_rqst		reqst, *call = &reqst;
+	sigset_t		oldset;
+	unsigned long		flags;
+	int			status, proto, vers;
+
+	vers = (NFS_PROTO(inode)->version == 3) ? 4 : 1;
+	if (NFS_PROTO(inode)->version > 3) {
+		printk(KERN_NOTICE "NFSv4 file locking not implemented!\n");
+		return -ENOLCK;
+	}
+
+	/* Retrieve transport protocol from NFS client */
+	proto = NFS_CLIENT(inode)->cl_xprt->prot;
+
+	if (!(host = nlmclnt_lookup_host(NFS_ADDR(inode), proto, vers)))
+		return -ENOLCK;
+
+	/* Create RPC client handle if not there, and copy soft
+	 * and intr flags from NFS client. */
+	if (host->h_rpcclnt == NULL) {
+		struct rpc_clnt	*clnt;
+
+		/* Bind an rpc client to this host handle (does not
+		 * perform a portmapper lookup) */
+		if (!(clnt = nlm_bind_host(host))) {
+			status = -ENOLCK;
+			goto done;
+		}
+		clnt->cl_softrtry = nfssrv->client->cl_softrtry;
+		clnt->cl_intr     = nfssrv->client->cl_intr;
+		clnt->cl_chatty   = nfssrv->client->cl_chatty;
+	}
+
+	/* Keep the old signal mask */
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	oldset = current->blocked;
+
+	/* If we're cleaning up locks because the process is exiting,
+	 * perform the RPC call asynchronously. */
+	if ((IS_SETLK(cmd) || IS_SETLKW(cmd))
+	    && fl->fl_type == F_UNLCK
+	    && (current->flags & PF_EXITING)) {
+		sigfillset(&current->blocked);	/* Mask all signals */
+		recalc_sigpending();
+		spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+		call = nlmclnt_alloc_call();
+		if (!call) {
+			status = -ENOMEM;
+			goto out_restore;
+		}
+		call->a_flags = RPC_TASK_ASYNC;
+	} else {
+		spin_unlock_irqrestore(&current->sighand->siglock, flags);
+		memset(call, 0, sizeof(*call));
+		locks_init_lock(&call->a_args.lock.fl);
+		locks_init_lock(&call->a_res.lock.fl);
+	}
+	call->a_host = host;
+
+	nlmclnt_locks_init_private(fl, host);
+
+	/* Set up the argument struct */
+	nlmclnt_setlockargs(call, fl);
+
+	if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
+		if (fl->fl_type != F_UNLCK) {
+			call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
+			status = nlmclnt_lock(call, fl);
+		} else
+			status = nlmclnt_unlock(call, fl);
+	} else if (IS_GETLK(cmd))
+		status = nlmclnt_test(call, fl);
+	else
+		status = -EINVAL;
+
+ out_restore:
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	current->blocked = oldset;
+	recalc_sigpending();
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+done:
+	dprintk("lockd: clnt proc returns %d\n", status);
+	nlm_release_host(host);
+	return status;
+}
+EXPORT_SYMBOL(nlmclnt_proc);
+
+/*
+ * Allocate an NLM RPC call struct
+ */
+struct nlm_rqst *
+nlmclnt_alloc_call(void)
+{
+	struct nlm_rqst	*call;
+
+	while (!signalled()) {
+		call = (struct nlm_rqst *) kmalloc(sizeof(struct nlm_rqst), GFP_KERNEL);
+		if (call) {
+			memset(call, 0, sizeof(*call));
+			locks_init_lock(&call->a_args.lock.fl);
+			locks_init_lock(&call->a_res.lock.fl);
+			return call;
+		}
+		printk("nlmclnt_alloc_call: failed, waiting for memory\n");
+		current->state = TASK_INTERRUPTIBLE;
+		schedule_timeout(5*HZ);
+	}
+	return NULL;
+}
+
+static int nlm_wait_on_grace(wait_queue_head_t *queue)
+{
+	DEFINE_WAIT(wait);
+	int status = -EINTR;
+
+	prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
+	if (!signalled ()) {
+		schedule_timeout(NLMCLNT_GRACE_WAIT);
+		try_to_freeze(PF_FREEZE);
+		if (!signalled ())
+			status = 0;
+	}
+	finish_wait(queue, &wait);
+	return status;
+}
+
+/*
+ * Generic NLM call
+ */
+static int
+nlmclnt_call(struct nlm_rqst *req, u32 proc)
+{
+	struct nlm_host	*host = req->a_host;
+	struct rpc_clnt	*clnt;
+	struct nlm_args	*argp = &req->a_args;
+	struct nlm_res	*resp = &req->a_res;
+	struct rpc_message msg = {
+		.rpc_argp	= argp,
+		.rpc_resp	= resp,
+	};
+	int		status;
+
+	dprintk("lockd: call procedure %d on %s\n",
+			(int)proc, host->h_name);
+
+	do {
+		if (host->h_reclaiming && !argp->reclaim)
+			goto in_grace_period;
+
+		/* If we have no RPC client yet, create one. */
+		if ((clnt = nlm_bind_host(host)) == NULL)
+			return -ENOLCK;
+		msg.rpc_proc = &clnt->cl_procinfo[proc];
+
+		/* Perform the RPC call. If an error occurs, try again */
+		if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
+			dprintk("lockd: rpc_call returned error %d\n", -status);
+			switch (status) {
+			case -EPROTONOSUPPORT:
+				status = -EINVAL;
+				break;
+			case -ECONNREFUSED:
+			case -ETIMEDOUT:
+			case -ENOTCONN:
+				nlm_rebind_host(host);
+				status = -EAGAIN;
+				break;
+			case -ERESTARTSYS:
+				return signalled () ? -EINTR : status;
+			default:
+				break;
+			}
+			break;
+		} else
+		if (resp->status == NLM_LCK_DENIED_GRACE_PERIOD) {
+			dprintk("lockd: server in grace period\n");
+			if (argp->reclaim) {
+				printk(KERN_WARNING
+				     "lockd: spurious grace period reject?!\n");
+				return -ENOLCK;
+			}
+		} else {
+			if (!argp->reclaim) {
+				/* We appear to be out of the grace period */
+				wake_up_all(&host->h_gracewait);
+			}
+			dprintk("lockd: server returns status %d\n", resp->status);
+			return 0;	/* Okay, call complete */
+		}
+
+in_grace_period:
+		/*
+		 * The server has rebooted and appears to be in the grace
+		 * period during which locks are only allowed to be
+		 * reclaimed.
+		 * We can only back off and try again later.
+		 */
+		status = nlm_wait_on_grace(&host->h_gracewait);
+	} while (status == 0);
+
+	return status;
+}
+
+/*
+ * Generic NLM call, async version.
+ */
+int
+nlmsvc_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
+{
+	struct nlm_host	*host = req->a_host;
+	struct rpc_clnt	*clnt;
+	struct rpc_message msg = {
+		.rpc_argp	= &req->a_args,
+		.rpc_resp	= &req->a_res,
+	};
+	int		status;
+
+	dprintk("lockd: call procedure %d on %s (async)\n",
+			(int)proc, host->h_name);
+
+	/* If we have no RPC client yet, create one. */
+	if ((clnt = nlm_bind_host(host)) == NULL)
+		return -ENOLCK;
+	msg.rpc_proc = &clnt->cl_procinfo[proc];
+
+        /* bootstrap and kick off the async RPC call */
+        status = rpc_call_async(clnt, &msg, RPC_TASK_ASYNC, callback, req);
+
+	return status;
+}
+
+static int
+nlmclnt_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
+{
+	struct nlm_host	*host = req->a_host;
+	struct rpc_clnt	*clnt;
+	struct nlm_args	*argp = &req->a_args;
+	struct nlm_res	*resp = &req->a_res;
+	struct rpc_message msg = {
+		.rpc_argp	= argp,
+		.rpc_resp	= resp,
+	};
+	int		status;
+
+	dprintk("lockd: call procedure %d on %s (async)\n",
+			(int)proc, host->h_name);
+
+	/* If we have no RPC client yet, create one. */
+	if ((clnt = nlm_bind_host(host)) == NULL)
+		return -ENOLCK;
+	msg.rpc_proc = &clnt->cl_procinfo[proc];
+
+	/* Increment host refcount */
+	nlm_get_host(host);
+        /* bootstrap and kick off the async RPC call */
+        status = rpc_call_async(clnt, &msg, RPC_TASK_ASYNC, callback, req);
+	if (status < 0)
+		nlm_release_host(host);
+	return status;
+}
+
+/*
+ * TEST for the presence of a conflicting lock
+ */
+static int
+nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
+{
+	int	status;
+
+	status = nlmclnt_call(req, NLMPROC_TEST);
+	nlmclnt_release_lockargs(req);
+	if (status < 0)
+		return status;
+
+	status = req->a_res.status;
+	if (status == NLM_LCK_GRANTED) {
+		fl->fl_type = F_UNLCK;
+	} if (status == NLM_LCK_DENIED) {
+		/*
+		 * Report the conflicting lock back to the application.
+		 */
+		locks_copy_lock(fl, &req->a_res.lock.fl);
+		fl->fl_pid = 0;
+	} else {
+		return nlm_stat_to_errno(req->a_res.status);
+	}
+
+	return 0;
+}
+
+static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
+{
+	memcpy(&new->fl_u.nfs_fl, &fl->fl_u.nfs_fl, sizeof(new->fl_u.nfs_fl));
+	nlm_get_lockowner(new->fl_u.nfs_fl.owner);
+}
+
+static void nlmclnt_locks_release_private(struct file_lock *fl)
+{
+	nlm_put_lockowner(fl->fl_u.nfs_fl.owner);
+	fl->fl_ops = NULL;
+}
+
+static struct file_lock_operations nlmclnt_lock_ops = {
+	.fl_copy_lock = nlmclnt_locks_copy_lock,
+	.fl_release_private = nlmclnt_locks_release_private,
+};
+
+static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
+{
+	BUG_ON(fl->fl_ops != NULL);
+	fl->fl_u.nfs_fl.state = 0;
+	fl->fl_u.nfs_fl.flags = 0;
+	fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner);
+	fl->fl_ops = &nlmclnt_lock_ops;
+}
+
+static void do_vfs_lock(struct file_lock *fl)
+{
+	int res = 0;
+	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
+		case FL_POSIX:
+			res = posix_lock_file_wait(fl->fl_file, fl);
+			break;
+		case FL_FLOCK:
+			res = flock_lock_file_wait(fl->fl_file, fl);
+			break;
+		default:
+			BUG();
+	}
+	if (res < 0)
+		printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n",
+				__FUNCTION__);
+}
+
+/*
+ * LOCK: Try to create a lock
+ *
+ *			Programmer Harassment Alert
+ *
+ * When given a blocking lock request in a sync RPC call, the HPUX lockd
+ * will faithfully return LCK_BLOCKED but never cares to notify us when
+ * the lock could be granted. This way, our local process could hang
+ * around forever waiting for the callback.
+ *
+ *  Solution A:	Implement busy-waiting
+ *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
+ *
+ * For now I am implementing solution A, because I hate the idea of
+ * re-implementing lockd for a third time in two months. The async
+ * calls shouldn't be too hard to do, however.
+ *
+ * This is one of the lovely things about standards in the NFS area:
+ * they're so soft and squishy you can't really blame HP for doing this.
+ */
+static int
+nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
+{
+	struct nlm_host	*host = req->a_host;
+	struct nlm_res	*resp = &req->a_res;
+	int		status;
+
+	if (!host->h_monitored && nsm_monitor(host) < 0) {
+		printk(KERN_NOTICE "lockd: failed to monitor %s\n",
+					host->h_name);
+		status = -ENOLCK;
+		goto out;
+	}
+
+	do {
+		if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0) {
+			if (resp->status != NLM_LCK_BLOCKED)
+				break;
+			status = nlmclnt_block(host, fl, &resp->status);
+		}
+		if (status < 0)
+			goto out;
+	} while (resp->status == NLM_LCK_BLOCKED && req->a_args.block);
+
+	if (resp->status == NLM_LCK_GRANTED) {
+		fl->fl_u.nfs_fl.state = host->h_state;
+		fl->fl_u.nfs_fl.flags |= NFS_LCK_GRANTED;
+		fl->fl_flags |= FL_SLEEP;
+		do_vfs_lock(fl);
+	}
+	status = nlm_stat_to_errno(resp->status);
+out:
+	nlmclnt_release_lockargs(req);
+	return status;
+}
+
+/*
+ * RECLAIM: Try to reclaim a lock
+ */
+int
+nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl)
+{
+	struct nlm_rqst reqst, *req;
+	int		status;
+
+	req = &reqst;
+	memset(req, 0, sizeof(*req));
+	locks_init_lock(&req->a_args.lock.fl);
+	locks_init_lock(&req->a_res.lock.fl);
+	req->a_host  = host;
+	req->a_flags = 0;
+
+	/* Set up the argument struct */
+	nlmclnt_setlockargs(req, fl);
+	req->a_args.reclaim = 1;
+
+	if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0
+	 && req->a_res.status == NLM_LCK_GRANTED)
+		return 0;
+
+	printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
+				"(errno %d, status %d)\n", fl->fl_pid,
+				status, req->a_res.status);
+
+	/*
+	 * FIXME: This is a serious failure. We can
+	 *
+	 *  a.	Ignore the problem
+	 *  b.	Send the owning process some signal (Linux doesn't have
+	 *	SIGLOST, though...)
+	 *  c.	Retry the operation
+	 *
+	 * Until someone comes up with a simple implementation
+	 * for b or c, I'll choose option a.
+	 */
+
+	return -ENOLCK;
+}
+
+/*
+ * UNLOCK: remove an existing lock
+ */
+static int
+nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
+{
+	struct nlm_res	*resp = &req->a_res;
+	int		status;
+
+	/* Clean the GRANTED flag now so the lock doesn't get
+	 * reclaimed while we're stuck in the unlock call. */
+	fl->fl_u.nfs_fl.flags &= ~NFS_LCK_GRANTED;
+
+	if (req->a_flags & RPC_TASK_ASYNC) {
+		status = nlmclnt_async_call(req, NLMPROC_UNLOCK,
+					nlmclnt_unlock_callback);
+		/* Hrmf... Do the unlock early since locks_remove_posix()
+		 * really expects us to free the lock synchronously */
+		do_vfs_lock(fl);
+		if (status < 0) {
+			nlmclnt_release_lockargs(req);
+			kfree(req);
+		}
+		return status;
+	}
+
+	status = nlmclnt_call(req, NLMPROC_UNLOCK);
+	nlmclnt_release_lockargs(req);
+	if (status < 0)
+		return status;
+
+	do_vfs_lock(fl);
+	if (resp->status == NLM_LCK_GRANTED)
+		return 0;
+
+	if (resp->status != NLM_LCK_DENIED_NOLOCKS)
+		printk("lockd: unexpected unlock status: %d\n", resp->status);
+
+	/* What to do now? I'm out of my depth... */
+
+	return -ENOLCK;
+}
+
+static void
+nlmclnt_unlock_callback(struct rpc_task *task)
+{
+	struct nlm_rqst	*req = (struct nlm_rqst *) task->tk_calldata;
+	int		status = req->a_res.status;
+
+	if (RPC_ASSASSINATED(task))
+		goto die;
+
+	if (task->tk_status < 0) {
+		dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
+		goto retry_rebind;
+	}
+	if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
+		rpc_delay(task, NLMCLNT_GRACE_WAIT);
+		goto retry_unlock;
+	}
+	if (status != NLM_LCK_GRANTED)
+		printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
+die:
+	nlm_release_host(req->a_host);
+	nlmclnt_release_lockargs(req);
+	kfree(req);
+	return;
+ retry_rebind:
+	nlm_rebind_host(req->a_host);
+ retry_unlock:
+	rpc_restart_call(task);
+}
+
+/*
+ * Cancel a blocked lock request.
+ * We always use an async RPC call for this in order not to hang a
+ * process that has been Ctrl-C'ed.
+ */
+int
+nlmclnt_cancel(struct nlm_host *host, struct file_lock *fl)
+{
+	struct nlm_rqst	*req;
+	unsigned long	flags;
+	sigset_t	oldset;
+	int		status;
+
+	/* Block all signals while setting up call */
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	oldset = current->blocked;
+	sigfillset(&current->blocked);
+	recalc_sigpending();
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+	req = nlmclnt_alloc_call();
+	if (!req)
+		return -ENOMEM;
+	req->a_host  = host;
+	req->a_flags = RPC_TASK_ASYNC;
+
+	nlmclnt_setlockargs(req, fl);
+
+	status = nlmclnt_async_call(req, NLMPROC_CANCEL,
+					nlmclnt_cancel_callback);
+	if (status < 0) {
+		nlmclnt_release_lockargs(req);
+		kfree(req);
+	}
+
+	spin_lock_irqsave(&current->sighand->siglock, flags);
+	current->blocked = oldset;
+	recalc_sigpending();
+	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+	return status;
+}
+
+static void
+nlmclnt_cancel_callback(struct rpc_task *task)
+{
+	struct nlm_rqst	*req = (struct nlm_rqst *) task->tk_calldata;
+
+	if (RPC_ASSASSINATED(task))
+		goto die;
+
+	if (task->tk_status < 0) {
+		dprintk("lockd: CANCEL call error %d, retrying.\n",
+					task->tk_status);
+		goto retry_cancel;
+	}
+
+	dprintk("lockd: cancel status %d (task %d)\n",
+			req->a_res.status, task->tk_pid);
+
+	switch (req->a_res.status) {
+	case NLM_LCK_GRANTED:
+	case NLM_LCK_DENIED_GRACE_PERIOD:
+		/* Everything's good */
+		break;
+	case NLM_LCK_DENIED_NOLOCKS:
+		dprintk("lockd: CANCEL failed (server has no locks)\n");
+		goto retry_cancel;
+	default:
+		printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
+			req->a_res.status);
+	}
+
+die:
+	nlm_release_host(req->a_host);
+	nlmclnt_release_lockargs(req);
+	kfree(req);
+	return;
+
+retry_cancel:
+	nlm_rebind_host(req->a_host);
+	rpc_restart_call(task);
+	rpc_delay(task, 30 * HZ);
+}
+
+/*
+ * Convert an NLM status code to a generic kernel errno
+ */
+static int
+nlm_stat_to_errno(u32 status)
+{
+	switch(status) {
+	case NLM_LCK_GRANTED:
+		return 0;
+	case NLM_LCK_DENIED:
+		return -EAGAIN;
+	case NLM_LCK_DENIED_NOLOCKS:
+	case NLM_LCK_DENIED_GRACE_PERIOD:
+		return -ENOLCK;
+	case NLM_LCK_BLOCKED:
+		printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
+		return -ENOLCK;
+#ifdef CONFIG_LOCKD_V4
+	case NLM_DEADLCK:
+		return -EDEADLK;
+	case NLM_ROFS:
+		return -EROFS;
+	case NLM_STALE_FH:
+		return -ESTALE;
+	case NLM_FBIG:
+		return -EOVERFLOW;
+	case NLM_FAILED:
+		return -ENOLCK;
+#endif
+	}
+	printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
+	return -ENOLCK;
+}