patch-2.1.32 linux/fs/lockd/clntproc.c

• Lines: 540
• Date: Fri Apr 4 11:06:05 1997
• Orig file: v2.1.31/linux/fs/lockd/clntproc.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.31/linux/fs/lockd/clntproc.c linux/fs/lockd/clntproc.c
@@ -0,0 +1,539 @@
+/*
+ * linux/fs/lockd/clntproc.c
+ *
+ * RPC procedures for the client side NLM implementation
+ *
+ * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/nfs_fs.h>
+#include <linux/utsname.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
+
+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);
+
+/*
+ * Cookie counter for NLM requests
+ */
+static u32	nlm_cookie = 0x1234;
+
+/*
+ * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
+ */
+static inline void
+nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
+{
+	struct nlm_args	*argp = &req->a_args;
+	struct nlm_lock	*lock = &argp->lock;
+
+	memset(argp, 0, sizeof(*argp));
+	argp->cookie  = nlm_cookie++;
+	argp->state   = nsm_local_state;
+	lock->fh      = *NFS_FH(fl->fl_file->f_inode);
+	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);
+	lock->fl      = *fl;
+}
+
+/*
+ * Initialize arguments for GRANTED call
+ */
+int
+nlmclnt_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
+{
+	struct nlm_args	*argp = &call->a_args;
+	struct nlm_lock	*alock = &argp->lock;
+	void		*data = NULL;
+
+	if (lock->oh.len > NLMCLNT_OHSIZE
+	 && !(data = kmalloc(lock->oh.len, GFP_KERNEL)))
+		return 0;
+
+	argp->cookie  = nlm_cookie++;
+	argp->lock    = *lock;
+	alock->caller = system_utsname.nodename;
+	if (data)
+		alock->oh.data = (u8 *) data;
+	else
+		alock->oh.data = call->a_owner;
+	memcpy(alock->oh.data, lock->oh.data, lock->oh.len);
+	return 1;
+}
+
+void
+nlmclnt_freegrantargs(struct nlm_rqst *call)
+{
+	kfree(call->a_args.lock.caller);
+}
+
+/*
+ * 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;
+	unsigned long		oldmask;
+	int			status;
+
+	/* Always use NLM version 1 over UDP for now... */
+	if (!(host = nlmclnt_lookup_host(NFS_ADDR(inode), IPPROTO_UDP, 1)))
+		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 */
+	oldmask = current->blocked;
+
+	/* If we're cleaning up locks because the process is exiting,
+	 * perform the RPC call asynchronously. */
+	if (cmd == F_SETLK && fl->fl_type == F_UNLCK
+	 && (current->flags & PF_EXITING)) {
+		current->blocked = ~0UL;	/* Mask all signals */
+		call = nlmclnt_alloc_call();
+		call->a_flags = RPC_TASK_ASYNC;
+	} else {
+		call->a_flags = 0;
+	}
+	call->a_host = host;
+
+	/* Set up the argument struct */
+	nlmclnt_setlockargs(call, fl);
+
+	if (cmd == F_GETLK) {
+		status = nlmclnt_test(call, fl);
+	} else if (cmd == F_SETLK && fl->fl_type == F_UNLCK) {
+		status = nlmclnt_unlock(call, fl);
+	} else if (cmd == F_SETLK || cmd == F_SETLKW) {
+		call->a_args.block = (cmd == F_SETLKW)? 1 : 0;
+		status = nlmclnt_lock(call, fl);
+	} else {
+		status = -EINVAL;
+	}
+
+	if (status < 0 && (call->a_flags & RPC_TASK_ASYNC))
+		rpc_free(call);
+
+	current->blocked = oldmask;
+
+done:
+	dprintk("lockd: clnt proc returns %d\n", status);
+	nlm_release_host(host);
+	return status;
+}
+
+/*
+ * Wait while server is in grace period
+ */
+static inline int
+nlmclnt_grace_wait(struct nlm_host *host)
+{
+	if (!host->h_reclaiming)
+		current->timeout = 10 * HZ;
+	interruptible_sleep_on(&host->h_gracewait);
+	return signalled()? -ERESTARTSYS : 0;
+}
+
+/*
+ * Allocate an NLM RPC call struct
+ */
+struct nlm_rqst *
+nlmclnt_alloc_call(void)
+{
+	struct nlm_rqst	*call;
+
+	while (!signalled()) {
+		call = (struct nlm_rqst *) rpc_allocate(RPC_TASK_ASYNC,
+					sizeof(struct nlm_rqst));
+		if (call)
+			return call;
+		current->timeout = 5 * HZ;
+		current->state = TASK_INTERRUPTIBLE;
+		schedule();
+	}
+	return NULL;
+}
+
+/*
+ * Generic NLM call
+ */
+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;
+	int		status;
+
+	dprintk("lockd: call procedure %s on %s\n",
+			nlm_procname(proc), host->h_name);
+
+	do {
+		if (host->h_reclaiming && !argp->reclaim) {
+			interruptible_sleep_on(&host->h_gracewait);
+			continue;
+		}
+
+		/* If we have no RPC client yet, create one. */
+		if ((clnt = nlm_bind_host(host)) == NULL)
+			return -ENOLCK;
+
+		/* Perform the RPC call. If an error occurs, try again */
+		if ((status = rpc_call(clnt, proc, argp, resp, 0)) < 0) {
+			dprintk("lockd: rpc_call returned error %d\n", -status);
+			if (status == -ERESTARTSYS)
+				return status;
+			nlm_rebind_host(host);
+		} 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 {
+			dprintk("lockd: server returns status %d\n", resp->status);
+			return 0;	/* Okay, call complete */
+		}
+
+		/* Back off a little and try again */
+		current->timeout = jiffies + 15 * HZ;
+		interruptible_sleep_on(&host->h_gracewait);
+	} while (!signalled());
+
+	return -ERESTARTSYS;
+}
+
+/*
+ * Generic NLM call, async version.
+ */
+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;
+	int		status;
+
+	dprintk("lockd: call procedure %s on %s (async)\n",
+			nlm_procname(proc), host->h_name);
+
+	/* If we have no RPC client yet, create one. */
+	if ((clnt = nlm_bind_host(host)) == NULL)
+		return -ENOLCK;
+
+        /* bootstrap and kick off the async RPC call */
+        status = rpc_do_call(clnt, proc, argp, resp, RPC_TASK_ASYNC,
+					callback, req);
+
+	/* If the async call is proceeding, increment host refcount */
+        if (status >= 0 && (req->a_flags & RPC_TASK_ASYNC))
+                host->h_count++;
+	return status;
+}
+
+/*
+ * TEST for the presence of a conflicting lock
+ */
+static int
+nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
+{
+	int	status;
+
+	if ((status = nlmclnt_call(req, NLMPROC_TEST)) < 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.
+		 * FIXME: Is it OK to report the pid back as well?
+		 */
+		memcpy(fl, &req->a_res.lock.fl, sizeof(*fl));
+		/* fl->fl_pid = 0; */
+	} else {
+		return nlm_stat_to_errno(req->a_res.status);
+	}
+
+	return 0;
+}
+
+/*
+ * 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", host->h_name);
+		return -ENOLCK;
+	}
+
+	while (1) {
+		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)
+			return status;
+	}
+
+	if (resp->status == NLM_LCK_GRANTED) {
+		fl->fl_u.nfs_fl.state = host->h_state;
+		fl->fl_u.nfs_fl.flags |= NFS_LCK_GRANTED;
+	}
+
+	return nlm_stat_to_errno(resp->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;
+	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) {
+		return nlmclnt_async_call(req, NLMPROC_UNLOCK,
+					nlmclnt_unlock_callback);
+	}
+
+	if ((status = nlmclnt_call(req, NLMPROC_UNLOCK)) < 0)
+		return status;
+
+	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);
+		nlm_rebind_host(req->a_host);
+		rpc_restart_call(task);
+		return;
+	}
+	if (status != NLM_LCK_GRANTED
+	 && status != NLM_LCK_DENIED_GRACE_PERIOD) {
+		printk("lockd: unexpected unlock status: %d\n", status);
+	}
+
+die:
+	rpc_release_task(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	oldmask = current->blocked;
+	int		status;
+
+	/* Block all signals while setting up call */
+	current->blocked = ~0UL;
+
+	do {
+		req = (struct nlm_rqst *) rpc_allocate(RPC_TASK_ASYNC,
+							sizeof(*req));
+	} while (req == NULL);
+	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)
+		rpc_free(req);
+
+	current->blocked = oldmask;
+	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)");
+		goto retry_cancel;
+	default:
+		printk(KERN_NOTICE "lockd: weird return %d for CANCEL call",
+			req->a_res.status);
+	}
+
+die:
+	rpc_release_task(task);
+	nlm_release_host(req->a_host);
+	kfree(req);
+	return;
+
+retry_cancel:
+	nlm_rebind_host(req->a_host);
+	rpc_restart_call(task);
+	rpc_delay(task, 30 * HZ);
+	return;
+}
+
+/*
+ * 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;
+	}
+	printk(KERN_NOTICE "lockd: unexpected server status %d\n", status);
+	return -ENOLCK;
+}