[PATCH] Fix posix file locking (7/9)

VFS,CIFS,NLM,NFSv4: make filesystems directly responsible for calling
   posix_lock_file() if they need it. This fixes an NFS race whereby
   in case of a server reboot, the recovery thread could re-establish
   a lock that had just been freed.
Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/cifs/file.c

@@ -569,6 +569,8 @@ cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
 			 netfid, length,
 			 pfLock->fl_start, numUnlock, numLock, lockType,
 			 wait_flag);
+	if (rc == 0 && (pfLock->fl_flags & FL_POSIX))
+		posix_lock_file(file, pfLock);
 	FreeXid(xid);
 	return rc;
 }

fs/lockd/clntproc.c

@@ -561,6 +561,10 @@ nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 	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;
+		if (posix_lock_file_wait(fl->fl_file, fl) < 0)
+				printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n",
+						__FUNCTION__);
 	}
 	status = nlm_stat_to_errno(resp->status);
 out:
@@ -627,6 +631,9 @@ nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 	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 */
+		posix_lock_file(fl->fl_file, fl);
 		if (status < 0) {
 			nlmclnt_release_lockargs(req);
 			kfree(req);
@@ -639,6 +646,7 @@ nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 	if (status < 0)
 		return status;
 
+	posix_lock_file(fl->fl_file, fl);
 	if (resp->status == NLM_LCK_GRANTED)
 		return 0;
 
@@ -669,7 +677,6 @@ nlmclnt_unlock_callback(struct rpc_task *task)
 	}
 	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);

fs/locks.c

@@ -906,6 +906,34 @@ int posix_lock_file(struct file *filp, struct file_lock *fl)
 	return __posix_lock_file(filp->f_dentry->d_inode, fl);
 }
 
+/**
+ * posix_lock_file_wait - Apply a POSIX-style lock to a file
+ * @filp: The file to apply the lock to
+ * @fl: The lock to be applied
+ *
+ * Add a POSIX style lock to a file.
+ * We merge adjacent & overlapping locks whenever possible.
+ * POSIX locks are sorted by owner task, then by starting address
+ */
+int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
+{
+	int error;
+	might_sleep ();
+	for (;;) {
+		error = __posix_lock_file(filp->f_dentry->d_inode, fl);
+		if ((error != -EAGAIN) || !(fl->fl_flags & FL_SLEEP))
+			break;
+		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
+		if (!error)
+			continue;
+
+		locks_delete_block(fl);
+		break;
+	}
+	return error;
+}
+EXPORT_SYMBOL(posix_lock_file_wait);
+
 /**
  * locks_mandatory_locked - Check for an active lock
  * @inode: the file to check
@@ -1483,8 +1511,7 @@ int fcntl_setlk(struct file *filp, unsigned int cmd, struct flock __user *l)
 
 	if (filp->f_op && filp->f_op->lock != NULL) {
 		error = filp->f_op->lock(filp, cmd, file_lock);
-		if (error < 0)
-			goto out;
+		goto out;
 	}
 
 	for (;;) {
@@ -1618,8 +1645,7 @@ int fcntl_setlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
 
 	if (filp->f_op && filp->f_op->lock != NULL) {
 		error = filp->f_op->lock(filp, cmd, file_lock);
-		if (error < 0)
-			goto out;
+		goto out;
 	}
 
 	for (;;) {
@@ -1671,7 +1697,7 @@ void locks_remove_posix(struct file *filp, fl_owner_t owner)
 
 	if (filp->f_op && filp->f_op->lock != NULL) {
 		filp->f_op->lock(filp, F_SETLK, &lock);
-		/* Ignore any error -- we must remove the locks anyway */
+		goto out;
 	}
 
 	/* Can't use posix_lock_file here; we need to remove it no matter
@@ -1687,6 +1713,7 @@ void locks_remove_posix(struct file *filp, fl_owner_t owner)
 		before = &fl->fl_next;
 	}
 	unlock_kernel();
+out:
 	if (lock.fl_ops && lock.fl_ops->fl_release_private)
 		lock.fl_ops->fl_release_private(&lock);
 }

fs/nfs/nfs4proc.c

@@ -1856,6 +1856,8 @@ nfs4_proc_unlck(struct nfs4_state *state, int cmd, struct file_lock *request)
 	nfs4_put_lock_state(lsp);
 out:
 	up(&state->lock_sema);
+	if (status == 0)
+		posix_lock_file(request->fl_file, request);
 	return nfs4_map_errors(status);
 }
 
@@ -1932,6 +1934,12 @@ nfs4_proc_setlk(struct nfs4_state *state, int cmd, struct file_lock *request)
 	nfs4_put_lock_state(lsp);
 out:
 	up(&state->lock_sema);
+	if (status == 0) {
+		/* Note: we always want to sleep here! */
+		request->fl_flags |= FL_SLEEP;
+		if (posix_lock_file_wait(request->fl_file, request) < 0)
+			printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __FUNCTION__);
+	}
 	return nfs4_map_errors(status);
 }
 

include/linux/fs.h

@@ -690,6 +690,7 @@ extern void locks_remove_posix(struct file *, fl_owner_t);
 extern void locks_remove_flock(struct file *);
 extern struct file_lock *posix_test_lock(struct file *, struct file_lock *);
 extern int posix_lock_file(struct file *, struct file_lock *);
+extern int posix_lock_file_wait(struct file *, struct file_lock *);
 extern void posix_block_lock(struct file_lock *, struct file_lock *);
 extern void posix_unblock_lock(struct file *, struct file_lock *);
 extern int posix_locks_deadlock(struct file_lock *, struct file_lock *);